gold ball mill name with address

how much the gold ore ball mill - jxsc machine

Capacity 0.65~130 t/h Feeding size 20-25mm Discharge size 0.074-0.89mm Grinding ball 1.5-338t Application gold ore and other ores grinding Advantages Rolling bearing has little friction and low consumption; Reasonable sealing, low failure; Little dust, low noise, energy-saving; Special design, good grinding effect, 60s manual response, 24hrs quotation. More ball mill model details

Since most of the gold mines contain impurities, we only can obtain the gold concentrate after a series of steps such as crushing, grinding, and sieving. The ball mill plays an important role in the gold ore grinding process, as a kind of high-efficiency fine grinding equipment, it has been widely used in fine grinding and ultra-fine grinding operations in mining, chemical, new materials, building materials and other fields. In the gold mining plant, the ball mill usually set after the jaw crusher, in a second-stage grinding, process sulfur-containing arsenic-containing refractory gold ore, and tailings treatment. The outstanding advantages of gold ball mill are low energy consumption, ultra-fine grinding, simple foundation, low noise and vibration, and has been regarded as an efficient new fine grinding equipment.

The main parts of the gold ore ball mill includes the feeding, the supporting device, the rotating part, the unloading device and the transmission device. Working principle: gold ore ball mill is a low-speed rotary cylinder horizontally mounted on the bearing. In the rotary cylinder, there are heavy steel balls. Along the motor and gear rotates the cylinder, generating centrifugal force to bring the steel ball to a certain height and then falling. The ore material are gradually crushed and ground by the steel ball impact force. The material is subjected to impact crushing and grinding, and the material is slowly flowed from the feeding end to the discharging end by the material level difference, until the material is discharged. That is the overflow ball mill.

Gold ore ball mill is especially suitable for two-stage grinding or ultra-fine grinding because of its advantages of ultra-fine grinding, high efficiency and energy-saving, low installation cost and low wear.

A gold mine used the JXSC gold ore ball mill for the second stage grinding to technically transform the original process, and achieved good results. After the transformation, the production capacity reached 130~140t/d. The production results show that the JXSC gold mine ball mill has low electromechanical consumption, high grinding efficiency, low wear of wearing parts and vibration noise less than 85dB.

There are rich sulfur-bearing and arsenic-containing refractory gold ore resources, but due to the lack of practical technology, these gold resources are not fully utilized. The JXSC Gold Mining Ball Mill has two basic characteristics of ultra-fine grinding and enhanced chemical leaching. The use of ultra-fine grinding of the JXSC gold ore ball mill can strengthen the alkali leaching, which may provide a technically feasible and economically reasonable treatment process for some sulfur-containing and arsenic-containing refractory gold ores.

Ball mill superfine grinding for secondary utilization of gold-bearing tailings in which gold was not fully recovered in the old days due to the technique limitation. In some gold tailings, the gold content is as high as 2~8g/t, if using the JXSC gold ore ball mill to retreat and recover gold, its potential economic benefits are huge.

The ball mill price are determined by many factors, such as machine weight, cylinder material, steel ball material, motor brand, lined plate thickness and material, etc. A professional and reasonable quotation made on your mine conditions, mine minerals, capacity, rock hardness, clay, etc. We are here to help.

JXSC is a 35 years Chinese mining equipment manufacturer, has great quality & price advantages in the ball mill, jaw crusher, trommel scrubber, shaker table and so on. Contact us for a 12hrs quotation.

major mines & projects | rainy river mine

The Rainy River deposit is an auriferous VMS system (Pelletier 2016) with a primary syn-volcanic source and possibly a secondary syn-tectonic mineralization event.At Rainy River, gold and silver are the dominant metals and the base metal (Cu-Pb-Zn) sulphides, although good indicators of the presence of gold, represent less than 10%, by volume, of the host rock. This is in contrast with other VMS systems that generally contain large amounts of base metals. However, there are exceptions, i.e., gold-rich VMS deposits that often contain modest amounts of base metals relative to gold (Mercier-Langevin et al. 2015 and references therein).The Rainy River deposit occurs within a sequence of felsic to intermediate, calc-alkaline metavolcanic rocks which is bounded to both the north and south by a lower mafic volcanic sequence. This mafic sequence is intruded by the trondhjemitic Sabaskong batholith to the north. Felsic to intermediate rocks are intruded to the east of the deposit by the Black Hawk monzonitic stock. In the deposit area all rock units strike approximately east-west and dip to the south, subparallel to the main foliation recognized in the area.The Rainy River deposit comprises eight distinct zones of gold and silver mineralization. The bulk of the gold mineralization at Rainy River is contained in sulphide and quartz-sulphide stringers and veins hosted by felsic quartz-phyric rocks.ODM/17 ZoneThe ODM/17 Zone is a series of east-west trending, south dipping lenticular sheets hosted within calc-alkaline dacites of the intermediate fragmental volcanic succession. The zone is cut by numerous NNE trending faults. The ODM/17 Zone has presently been defined over a strike extent of 1,600 m and to depths of 975 m. The true width of the zone is approximately 200 m.Three styles of gold mineralization are observed in the ODM/17 Zone. Low grade intervals are characterized by tightly folded pyrite stringer veins and disseminated pyrite in sericite quartzchlorite altered host rocks. Moderate-grade intervals are characterized by tightly folded and foliation parallel pyrite-sphalerite and pyrite stringer veins, commonly associated with stronger silica and weak garnet alteration.433 ZoneThe 433 Zone is located approximately 500 m north of the ODM/17 Zone and hosted within strongly sericitized calc alkaline dacite rocks and lesser tholeiitic basalts. The 433 Zone comprises a cigar-shaped lens which plunges steeply south-west. This zone has a strike length of 325 m, a vertical distance of approximately 820 m, and a true width of up to 125 m.Gold mineralization is similar in style to the ODM/17 Zone but with a number of minor differences:- The 433 Zone is dominated by chlorite alteration of quartz-phyric host rocks as opposed to sericite in the ODM/17 Zone.- Chlorite-pyrite altered heterolithic conglomerates occur within the 433 Zone.- Chalcopyrite and chlorite are associated with high-grade quartz-pyrite-gold veinlets. Footwall Silver ZoneThe Footwall Silver Zone occurs in altered dacitic tuffs and tuff breccias immediately adjacent to a high strain zone at the northern contact of the ODM/17 Zone. This zone plunges to the south west in similar orientation to the ODM/17 Zone. It is hosted by centimetre scale sulphide-bearing quartz veinlets with common millimetre scale fracture filling to dendritic native silver inclusions. Sulphides contained within these veinlets, in order of frequency, comprise pyrite, sphalerite, chalcopyrite, and galena. Localized spessartine garnets have been noted. The presence of isoclinal folding of the veinlets suggest mineralization occurred prior to or synchronous with deformation. The zone is considered to genetically related to the ODM/17 Zone. The zone is composed of numerous lenses that range from 5 to 30 m wide, have strike lengths between 5 to 50 m and plunge extents between 300 and 600 m.HS ZonesSeveral subsidiary zones of gold mineralization occur between the ODM/17 Zone and 433 Zone. The HS Zones comprise a series of small, discontinuous south-west plunging, flattened shoots of mineralization. Discontinuous, irregular low-grade gold mineralization is associated with chlorite-pyrite replacement of matrix in flattened, albitized, heterolithic pebble conglomerates. The zone has a strike length of 200 m and extends to a vertical distance of approximately 700 m.The Western ZoneThe Western Zone occurs near surface approximately 500 m north-west of the western extent of the ODM/17 Zone. It is composed of stockwork of discrete centimetre scale anastomosing, folded to linear quartz and quartz-carbonate veinlets. The Western Zone is hosted predominantly within strongly deformed intermediate volcanic fragmental units (analogous to those that host the ODM/17 Zone) and mafic volcanic flows in the immediate footwall (FW) and hangingwall (HW). The Western Zone comprises a series of discontinuous 5 to 10 m wide zones of mineralization which strike approximately south-east and dip south-west at approximately 50. Individual zones encompass a strike length of between 50 and 500 m. Collectively these zones occur over an area of approximately 500 x 1,200 m. They have been defined to down-dip depths of approximately 60 to 500 m.The CAP ZoneThe CAP Zone is located approximately 200 m to the south of the ODM/17 Zone in both tholeiitic basalts and calc-alkaline dacite of the upper diverse mafic volcanic succession. The CAP Zone has been defined over a strike length of 400 m, up to 120 m wide and with a down-dip extent of 750 m. Mineralization in the CAP Zone is open below the modelled depth. Higher-grade gold mineralization is associated with deformed quartz-ankerite-pyrite shear and extensional veins hosted by quartz-ankerite-pyrite altered mafic volcanic rocks.Intrepid ZoneThe Intrepid Zone is located approximately 800 m east of the ODM/17 Zone within dacitic\ tuffs and breccias of the intermediate fragmental volcanic succession. The Intrepid Zone has been defined over a strike length of 410 m and to 450 m down-dip. The width of the zone is variable ranging between 10 m to 60 m.High-grade gold and silver mineralization is associated with deformed quartz-pyrite-gold, quartz-pyrite-silver, or quartz-pyrite-gold-silver veinlets that overprint other mineralization styles. The gold-silver ratio is determined by their location within the base metal zonation.34 ZoneThe 34 Zone comprises magmatic nickel copper sulphide mineralization associated with precious metals (gold, platinum group metals) within a tubular, ~100 m thick, late-stage pyroxenite gabbro intrusion which cross cuts the ODM/17 Zone and post-dates the main gold mineralization event. The host pyroxenite-gabbro intrusion is unmetamorphosed, but locally altered into serpentine and talc. Magmatic sulphides vary from massive to net-textured and disseminated. Gold and silver mineralization occur within 5 to 50 m thick dislocated (and therefor discontinuous) north-east oriented pods over a strike length of 500 m with a down-dip plunge of 100 m.

Mining at Rainy River is currently conducted using open pit mining methods and will transition into a combined open pit and underground operation over the next two years, with underground production commencing in 2022. An average processing rate of approximately 25,800 tpd is scheduled over the LOM.The open pit mine is a conventional truck and shovel mining operation, with a fleet of 220 t payload haul trucks combined with diesel powered hydraulic excavators and large front-end loaders (FELs) as primary loading units. The open pit operates at a peak mining rate of 151,000 tpd of ore and waste and has an overall strip ratio of 2.53:1 (waste:ore).Haulage ramps were designed nominally at 33 m width and a maximum 10% grade, except for the bottom few benches where widths were permitted to be reduced to one-way traffic of 20 m and 12% grade.The mine plan is executed to take advantage of the installed mine fleet productive capacity, allowing an elevated COG policy to be adapted, whereby higher-grade ores are preferentially sent to the mill for processing while lower grade ores are sent to stockpile for deferred processing. This results in an open pit mine life extending to Q1-2025 with stockpile rehandling occurring in parallel to the underground operations through to Q1-2028 to fulfill available process plant capacity.The Rainy River underground mining operation is planned to extract ore from five portals and / or zones: ODM Main Zone, ODE East Zone, 17 East Upper Zone, 433 Zone, and Intrepid Zone.Each of the underground zones is planned to be mined using one or both of the following mining methods:- Blind uphole LLHOS without backfill (uphole). Uphole is a top-down mining method that does not require the use of backfill. The uphole stopes have a minimum mining width of 3 m, a maximum width of 15 m, and an overall average width of 7.5 m. The sublevels will be spaced at 20 m intervals (floor to floor) in all zones except for the Intrepid Zone, where the stope heights have been increased to 25 m. Upholes are mined in a longitudinal retreat sequence, with open stopes up to 48 m long separated by a minimum 8 m wide pillar.- Downhole LLHOS with backfill (downhole). The downhole mining method is a bottom-up mining method that uses backfill. Downhole stopes are only used in the ODM Main Zone, where 90% of the stopes are planned as downhole and 10% are planned as uphole. The downhole stopes represent 32% of all projected stope tonnages for the underground LOM.The Intrepid Zone is the only zone with an existing portal and has approximately 166 m of decline development currently executed. The portal is at 365 RL and planned stopes are located between 225 RL and 100 RL. The zone extends approximately 250 m horizontally and dips between 50 and 70.

CrushingThe crusher consists of a 1,400 mm x 2,100 mm, 600 kW gyratory crusher. The crusher is designed for 220 t mine haul trucks to dump directly into the crusher feed pocket. Two dump positions on opposite sides of the crusher allow for simultaneous dumping. The capacity of the dump pocket is 330 t or approximately 1.5 trucks. The crusher is equipped with a hydraulic rock breaker for reducing oversized material and a mobile crane is available for crusher maintenance.The crusher is designed to process 1,346 tph of ore with a F100 feed size of 1,050 mm, a F80 of 550 mm and an operating availability of 65%. The crusher operates with an open side setting of 120 mm to produce a P80 product size of about 120 mm. The crusher discharge surge pocket live capacity is 418 t or approximately 1.9 trucks. Ore is removed from the discharge surge pocket by a single 2,134 mm wide apron feeder, FE01, which discharges onto the 1,372 mm wide crusher discharge conveyor, CV10. The crusher discharge conveyor then transfers ore to the 1,372 mm wide coarse ore stockpile feed conveyor, CV 11. CV11 transports the ore to the coarse ore stockpile. CV10 is equipped with a weightometer to measure the crusher production rate and total ore processed. In addition, CV10 has a metal detector that shuts down the conveyor belt automatically, permitting the operators to extract the metal detected.The coarse ore stockpile has a total capacity of 85,700 t and a live capacity of 19,000 t. Ore is drawn from the coarse ore stockpile by three apron feeders. The apron feeders discharge onto the 1,372 mm wide SAG mill feed conveyor, which is installed in a single reclaim tunnel beneath the stockpile. The SAG mill feed conveyor has a variable frequency drive (VFD) and delivers ore to the SAG mill feed chute. The SAG mill feed conveyor is equipped with a weightometer to monitor and control the SAG mill feed rate.Primary grinding SAG millThe SAG mill is an 11.0 m diameter by 6.1 m long grate discharge mill with a dual pinion drive consisting of two 7,500 kW motors with VFDs. The surveyed mill feed is a F80 of 46 mm and the discharge transfer P80 size is estimated to be 2.8 mm. The mill is currently operating at 58% of critical speed to achieve a production rate of 1,050 1,350 tph. The design operating power at the pinions is 12,580 kW, which is approximately 84% of the installed power. The mill currently has a grate discharge of 70 mm pebble ports.The mill discharge is fitted with a single deck horizontal vibrating screen with 10.5 mm openings to remove oversized pebble, ball chips and tramp steel. The SAG mill currently operates with a 10% - 14% solids (v/v) ball charge made up with 130 mm balls and a total charge volume of 25% (v/v). The maximum design ball charge is 16% (v/v) with a maximum design mill fill volume of 30% (v/v).The oversized pebble is conveyed from the SAG mill discharge screen to a Raptor L500, 3.5 m x 4.0 m x 3.6 m, pebble crusher (cone crusher), with a 447 kW drive via three conveyors, CV31, CV32, and CV33. Two belt magnets followed by a metal detector are installed on CV32. If metal is detected, a two-way gate will be opened and the metal containing ore is bypassed to a reject bin. The nominal operating rate of the crusher is 238 tph, 25% of nominal mill feed, with a design operating power draw of 235 kW. The crusher reduces the ore to an approximate P80 of 13 mm. The crushed product is conveyed to the SAG mill feed conveyor transfer tower where it is either discharged onto the SAG mill feed conveyor and recycled to the mill or fed to a bypass conveyor, which feeds a pebble stockpile adjacent to the conveyor transfer tower. The pebble crusher circuit assists in achieving the planned throughputs when the ore becomes harder. The pebble crusher circuit has been commissioned recently. The pebble crusher will not be operated unless the ore is sufficiently hard.Secondary grinding ball millThe ball mill is a 7.9 m diameter by 12.3 m long overflow mill with a dual pinion drive consisting of two 7,500 kW motors with VFDs. The typical mill feed has a F80 of 2,800 m and the resultant product size is currently a P80 range of 90 m - 110 m. The mill operates at 75% of critical speed to achieve a production rate of 1,050 1,350 tph. The design operating power at the pinions is 12,360 kW, which is approximately 82% of the installed power of 15,000 kW. The slurry discharges from the mill through a trunnion magnet for steel removal and into the cyclone feed pump box.The ball mill is operated with a target slurry density of 72% solids (w/w) and a circulating load of 300%. The maximum circulating load is projected to be 400%. The design ball charge is 32% (v/v) with a maximum design ball charge of 36% (v/v).

Gravity separationACACIA reactorCarbon re-activation kilnCentrifugal concentratorAgitated tank (VAT) leachingCarbon in pulp (CIP)ElutionCarbon adsorption-desorption-recovery (ADR)Solvent Extraction & ElectrowinningCyanide (reagent)

The process plant experienced initial operating and maintenance issues, but in 2019, Rainy River was consistently able to achieve daily plant throughputs in the 22,000 tpd - 24,000 tpd range. Throughput is programed to achieve approximately 25,300 tpd in 2020 with the LOM throughput averaging approximately 25,800 tpd.The process flowsheet consists of the following unit processes: Gyratory crusher. Coarse ore stockpile, discharged through draw pockets by apron feeders. SAG mill feed conveyor. SAG mill. Pebble crusher. Ball mill. Gravity concentration of cyclone feed slurry. Intensive cyanide leaching of the gravity concentrate using an Acacia reactor. Pre-leach thickener. Cyanide leaching. CIP circuit. Cyanide destruction using the sulphur dioxide-air process. Carbon stripping using the Zadra process. Electrowinning of the eluent and gravity concentrate leach solution. Ca ........

Reserves at December 31, 2020: For Mineral Reserves Lower Cut-off: O/P direct processing: 0.46 0.49 g/t AuEqO/P low grade material: 0.30 g/t AuEqU/G direct processing: 1.93 g/t AuEq.For Mineral Resources Lower Cut-off:O/P direct processing: 0.44 0.45 g/t AuEqO/P low grade material: 0.30 g/t AuEqU/G direct processing: 1.70 g/t AuEq.

major mines & projects | porcupine mine

The Porcupine mines are situated in the Porcupine Camp in Archean rocks of the western Abitibi Greenstone belt in the Canadian Shield. These consist of ultramafic and mafic volcanic rocks of the Keewatin subgroup overlain by sedimentary rocks of the Timiskaming group. The lands lie adjacent and to the north of the regionally significant Porcupine Destor Fault. Gold mineralization is found in a number of different structural settings and consists of continuous quartz carbonate veins, quartz tourmaline veins, quartz stockworks and gold associated with disseminated sulphides.Mineralization at Hollinger and Hoyle, in Timmins, comprises multiple generations of quartzcarbonate-tourmaline albite veins, associated pyrite alteration envelopes, and disseminated pyrite mineralization. Mineralization at Borden consists of a shear zone containing quartz-vein hosted sulfides within a high-grade metamorphic greenstone package.The Hoyle Pond.The Hoyle Pond Main Zone and 1060 Zone deposits occur on opposite limbs of an open, northeast-plunging antiformal structure, hosted within carbonatized north-dipping tholeiitic basalts. The 7 Vein System occurs as a series of stacked, flat to gently northeast-dipping veins in the nose of the antiformal structure.The Hoyle Pond Main Zone includes a series of generally northeast-striking, linked, quartz vein zones folded on a small scale with moderate west- and northeast-plunging axes.The 1060 Zone consists of at least five main vein structures (1060 B1, B2 and B3 zones, A zone and Porphyry zone) with orientations ranging from north to northeast and a generally subvertical dip. The veins are strongly boudinaged, with the long axis of the boudin oriented from subhorizontal to shallow westsouthwest plunging.AlterationThe mineralization at Hoyle Pond occurs as coarse free gold in white to greywhite quartz veins with a variable ankerite, tourmaline, pyrite, and locally arsenopyrite, content. Alteration halos are generally narrow, consisting of mainly grey zones (carbon, carbonate, sericite, cubic pyrite) in the Hoyle Pond system and carbonatesericite, plus fuchsite with pyrite, arsenopyrite and trace amounts of chalcopyrite and sphalerite within the 1060 structure.Gold at the Hoyle Pond Mine predominantly occurs as coarse free gold in white to greyishwhite quartz veins with variable ankerite, tourmaline, pyrite, pyrrhotite and local arsenopyrite. Trace amounts of chalcopyrite and sphalerite have also been noted.The Hoyle Pond Main Zone includes a series of generally northeast-striking, linked quartz vein zones. There are at least 11 veins of economic significance. These veins are folded on a small scale with moderate west and northeast plunging axes. The 1060 zone consists of at least five main vein structures with orientations ranging from north to northeast, are strongly boudinaged, and generally have a subvertical dip.A series of auriferous zones occurs along what is termed the South Trend, stretching from the Bell Creek deposit (to the west of Hoyle Pond) for 6.4 km to the 1060 zone (includes BlackhawkVogel deposit, Owl Creek West, Owl Creek, Owl Creek East and the 950 zone). Mineralization in these zones consists of quartzankerite veining with varying amounts of pyrite, pyrrhotite and free gold.The Borden Gold deposit.Owing to its metamorphic grade, the Borden Gold deposit is markedly different from most known Archean-aged mesothermal gold occurrences. On the basis of visual evidence, which is yet to be supported by detailed petrographic studies, it is believed that the Borden Gold deposit is most closely associated with the disseminated gold sub-class. The gold mineralization at the Borden Gold deposit occurs as a broad zone of disseminated and fracture-controlled sulphides within a volcano- metasedimentary package of variable composition. The main sulphides are pyrite and pyrrhotite, with the former typically dominating. The mineralization generally consists of low- to moderate-grade gold, with minor silver, and is characterized by a persistent higher-grade core surrounded by a lower-grade envelope. Results to date indicate that the higher-grade core improves in grade towards the southeast where it develops into a High-Grade Zone (HGZ) with average grades typically above 2.5 g/t Au. The northwest portions of the deposit are characterized by local silicification but lack lithological control and quartz veining; while to the southeast a well-developed hydrothermal system consisting of local quartz flooding and potassic alteration predominates and defines the HGZ. The broad mineralized zone encompasses multiple/variable host rocks, dominated by metasedimentary horizons and subordinate intrusives of acidic to intermediate composition, all of which display feldspathic, chloritic and biotitic alteration. Outcropping in the northwest parts of the deposit, the lower-grade mineralization rarely exhibits visible gold grains, while in the southeast HGZ it is much more common, particularly in the quartz-rich core. A higher-grade core is also consistently present within the lower-grade zone, locally attaining very high grades reminiscent of the HGZ.The deposit displays continuity and is consistently intersected along strike, reaching a current length of 3.7 kilometres, while remaining open in both the northwest and southeast directions. Structurally, the deposit is described by a consistent northeast dip and, locally, a shallow southeast plunge, which is mostly evident in the HGZ. Mineralization appears to be controlled by a ductile shear zone, which appears much better developed in the HGZ. The mineralized zone is up to 120 m wide, and has been confirmed to a vertical depth of approximately 650 m.

Porcupine, consists of the Hollinger open pit and Hoyle pond underground operations, located in the city of Timmins, Ontario, as well as the Borden underground operation, located near the town of Chapleau, Ontario. Borden mine is the worlds first all-electric underground mine.Currently, approximately 60% of the gold comes from the Hoyle Pond underground mine, where mechanized cut and fill and longhole mining methods are used to extract the ore, and the remaining ore comes from the Hollinger Open Pit mine. The Dome Underground mine ceased operations in 2017.Hollinger Open Pit mineThere is sufficient grade at specific gold price-points to mine a 150m deep pit, with the rock being processed at the nearby Dome Mine mill. The voids (sub-vertical stopes, shafts, and connecting drifts/drives) are sometimes spaced nearly 20-50m apart extending several hundred metres deep in a 2km square area beneath the City. The pit design was constrained by a regional highway (and the Citys water tower) along the northern wall, with homes and businesses on all other sides of the Property.The Hollinger is being mined using three 6m and two 9m cuts making up 18m high benches in mostly FAIR to GOOD ground. All blasting is done with blast-mats to reduce fly-rock and noise. Because the mine is in-town, damage needs to be minimised. Earlier, blast trials were conducted to determine the depth of blast-damage induced by varying sizes of confined blasts. These trials indicated that a three-row trim shot onto a pre-sheared final wall would not induce excessive damage. To reduce the damage further, the pre-shear drill-hole spacing is adjusted for ground conditions within the immediate vicinity of voids.This strategy sufficiently decreases the back-wall damage to less than 4m. The multi-use of probe holes to presupport the rock mass before blasting is part of the production cycle. Grouting cables into the final slopes, above and alongside voids, before blasting reduces the amount of final wall crown and wall rehabilitation required. This pattern has 8m cable-bolts on 4m spacing, drilled at -45 and -05 from the pre-shear line. On the North Wall, the dominant fabric (72/155) is the main control on the bench face angle. This highly foliated rock mass tends to delaminate when blasted. To reduce the bench-crest attrition from delamination, pre-support is applied using 6m cables on a 6m spacing, drilled at -45 into the crest from the pre-shear line.For each of the larger multi-bench voids encountered, individualised support designs are being implemented.Hoyle Pond underground mineAccess to the underground workings is by means of two ramps, one at either end of the ore body and a four-compartment shaft.Conventional cut and fill, shrinkage and panel mining methods are typically employed to excavate the narrower gold bearing vein structures. Each of the preceding mining methods is used to extract vein structures with vertical and/or near horizontal attitudes. Veins mined by these methods typically range from 0.20 meters to 2.0 meters thick and are usually higher grade material. Mucking is accomplished using appropriately sized slushers.Longhole methods with paste backfilling are used in wider stoping areas. Longhole levels are advanced at 60 meter intervals with sub levels at a 20 m interval. Haulage drifts are driven in the footwall about 12 meters offset from the ore zone. Backfilling methods were traditionally a combination of rock fill and cemented slag but these methods have been replaced with high quality paste backfill delivered through holes from surface and distributed with a network of underground piping.Borden mine is the worlds first all-electric underground mine.Commercial gold production at Borden began in October 2019.The Borden Gold Mine has an ore production capacity of 4000 tonnes per day over a mine life of up to 15 years. Mining method: - Sub-level retreat- Cemented rock fill with waste backhaul from PGM for waste requirement.- 15m longhole retreat factored 24% dilution - ~2000tpd ore @ 7gpt to mill using proven production rates- 5x5m main haulage drifts- Diesel trucks & tethered (electric) scoops until quick-charge battery alternate is viable. - Battery electric equipment

At the Dome mill, ore from PGMs mining operations is crushed in three stages to produce a product size of 80% passing ". Primary and secondary crushing is achieved in a 400 HP 42"x 65" gyratory and 400 HP 7' standard cone crusher, respectively. The latter feeds a 10' x 24' double deck screen in a closed circuit with a HP700 cone crusher. The screen undersize reports to two 4,000 tonne fine ore bins and the oversize is conveyed to a 75 tonne tertiary surge bin feeding the HP700 cone crusher. Due to the limited fine ore bin capacity, an external fine ore stockpile and reclaim conveyor system provide for supplemental mill feed during extended shutdowns of the crushing plants.Minus 1/2" material is fed to a grinding circuit that consists of two parallel grinding lines. Circuit A consists of a 10.5' diameter x 14' 700 HP rod mill and 13.5' x 20' 2200 HP ball mill while Circuit B consists of a 15' diameter x 20' 2200 HP rod mill and a 16' x 28.5' 4500 HP ball mill.

Gravity separationACACIA reactorSmeltingConcentrate leachAgitated tank (VAT) leachingCarbon in pulp (CIP)Carbon adsorption-desorption-recovery (ADR)ElutionSolvent Extraction & ElectrowinningCyanide (reagent)

At the Dome mill, ore from PGMs mining operations is crushed in three stages to produce a product size of 80% passing ".Gold is recovered using a combination of gravity concentration and cyanidation techniques. The circuit consists of primary, secondary and tertiary crushing, rod/ball mill grinding, gravity concentration, cyanide leaching, carbon-in-pulp gold recovery, stripping, electro winning and refining.Gravity gold is recovered by the use of five Knelson CD-30 Concentrators fed from the cyclone underflow. A Consep CS6000 Acacia Reactor is used to intensively leach the Knelson concentrate. The Acacia loaded solution has a dedicated electrowinning circuit. Gravity recovery accounts for up to 45% of the recovered gold, depending on ore type.The cyclone overflows reports to a 155' thickener where the slurry density is increased to 55-60% solids. The thickener underflow feeds six leach tanks in series, which provide about 32 hours residence time.< ........

ball mills

In all ore dressing and milling Operations, including flotation, cyanidation, gravity concentration, and amalgamation, the Working Principle is to crush and grind, often with rob mill & ball mills, the ore in order to liberate the minerals. In the chemical and process industries, grinding is an important step in preparing raw materials for subsequent treatment.In present day practice, ore is reduced to a size many times finer than can be obtained with crushers. Over a period of many years various fine grinding machines have been developed and used, but the ball mill has become standard due to its simplicity and low operating cost.

A ball millefficiently operated performs a wide variety of services. In small milling plants, where simplicity is most essential, it is not economical to use more than single stage crushing, because the Steel-Head Ball or Rod Mill will take up to 2 feed and grind it to the desired fineness. In larger plants where several stages of coarse and fine crushing are used, it is customary to crush from 1/2 to as fine as 8 mesh.

Many grinding circuits necessitate regrinding of concentrates or middling products to extremely fine sizes to liberate the closely associated minerals from each other. In these cases, the feed to the ball mill may be from 10 to 100 mesh or even finer.

Where the finished product does not have to be uniform, a ball mill may be operated in open circuit, but where the finished product must be uniform it is essential that the grinding mill be used in closed circuit with a screen, if a coarse product is desired, and with a classifier if a fine product is required. In most cases it is desirable to operate the grinding mill in closed circuit with a screen or classifier as higher efficiency and capacity are obtained. Often a mill using steel rods as the grinding medium is recommended, where the product must have the minimum amount of fines (rods give a more nearly uniform product).

Often a problem requires some study to determine the economic fineness to which a product can or should be ground. In this case the 911Equipment Company offers its complete testing service so that accurate grinding mill size may be determined.

Until recently many operators have believed that one particular type of grinding mill had greater efficiency and resulting capacity than some other type. However, it is now commonly agreed and accepted that the work done by any ballmill depends directly upon the power input; the maximum power input into any ball or rod mill depends upon weight of grinding charge, mill speed, and liner design.

The apparent difference in capacities between grinding mills (listed as being the same size) is due to the fact that there is no uniform method of designating the size of a mill, for example: a 5 x 5 Ball Mill has a working diameter of 5 inside the liners and has 20 per cent more capacity than all other ball mills designated as 5 x 5 where the shell is 5 inside diameter and the working diameter is only 48 with the liners in place.

Ball-Rod Mills, based on 4 liners and capacity varying as 2.6 power of mill diameter, on the 5 size give 20 per cent increased capacity; on the 4 size, 25 per cent; and on the 3 size, 28 per cent. This fact should be carefully kept in mind when determining the capacity of a Steel- Head Ball-Rod Mill, as this unit can carry a greater ball or rod charge and has potentially higher capacity in a given size when the full ball or rod charge is carried.

A mill shorter in length may be used if the grinding problem indicates a definite power input. This allows the alternative of greater capacity at a later date or a considerable saving in first cost with a shorter mill, if reserve capacity is not desired. The capacities of Ball-Rod Mills are considerably higher than many other types because the diameters are measured inside the liners.

The correct grinding mill depends so much upon the particular ore being treated and the product desired, that a mill must have maximum flexibility in length, type of grinding medium, type of discharge, and speed.With the Ball-Rod Mill it is possible to build this unit in exact accordance with your requirements, as illustrated.

To best serve your needs, the Trunnion can be furnished with small (standard), medium, or large diameter opening for each type of discharge. The sketch shows diagrammatic arrangements of the four different types of discharge for each size of trunnion opening, and peripheral discharge is described later.

Ball-Rod Mills of the grate discharge type are made by adding the improved type of grates to a standard Ball-Rod Mill. These grates are bolted to the discharge head in much the same manner as the standard headliners.

The grates are of alloy steel and are cast integral with the lifter bars which are essential to the efficient operation of this type of ball or rod mill. These lifter bars have a similar action to a pump:i. e., in lifting the product so as to discharge quickly through the mill trunnion.

These Discharge Grates also incorporate as an integral part, a liner between the lifters and steel head of the ball mill to prevent wear of the mill head. By combining these parts into a single casting, repairs and maintenance are greatly simplified. The center of the grate discharge end of this mill is open to permit adding of balls or for adding water to the mill through the discharge end.

Instead of being constructed of bars cast into a frame, Grates are cast entire and have cored holes which widen toward the outside of the mill similar to the taper in grizzly bars. The grate type discharge is illustrated.

The peripheral discharge type of Ball-Rod Mill is a modification of the grate type, and is recommended where a free gravity discharge is desired. It is particularly applicable when production of too many fine particles is detrimental and a quick pass through the mill is desired, and for dry grinding.

The drawings show the arrangement of the peripheral discharge. The discharge consists of openings in the shell into which bushings with holes of the desired size are inserted. On the outside of the mill, flanges are used to attach a stationary discharge hopper to prevent pulp splash or too much dust.

The mill may be operated either as a peripheral discharge or a combination or peripheral and trunnion discharge unit, depending on the desired operating conditions. If at any time the peripheral discharge is undesirable, plugs inserted into the bushings will convert the mill to a trunnion discharge type mill.

Unless otherwise specified, a hard iron liner is furnished. This liner is made of the best grade white iron and is most serviceable for the smaller size mills where large balls are not used. Hard iron liners have a much lower first cost.

Electric steel, although more expensive than hard iron, has advantage of minimum breakage and allows final wear to thinner section. Steel liners are recommended when the mills are for export or where the source of liner replacement is at a considerable distance.

Molychrome steel has longer wearing qualities and greater strength than hard iron. Breakage is not so apt to occur during shipment, and any size ball can be charged into a mill equipped with molychrome liners.

Manganese liners for Ball-Rod Mills are the world famous AMSCO Brand, and are the best obtainable. The first cost is the highest, but in most cases the cost per ton of ore ground is the lowest. These liners contain 12 to 14% manganese.

The feed and discharge trunnions are provided with cast iron or white iron throat liners. As these parts are not subjected to impact and must only withstand abrasion, alloys are not commonly used but can be supplied.

Gears for Ball-Rod Mills drives are furnished as standard on the discharge end of the mill where they are out of the way of the classifier return, scoop feeder, or original feed. Due to convertible type construction the mills can be furnished with gears on the feed end. Gear drives are available in two alternative combinations, which are:

All pinions are properly bored, key-seated, and pressed onto the steel countershaft, which is oversize and properly keyseated for the pinion and drive pulleys or sheaves. The countershaft operates on high grade, heavy duty, nickel babbitt bearings.

Any type of drive can be furnished for Ball-Rod Mills in accordance with your requirements. Belt drives are available with pulleys either plain or equipped with friction clutch. Various V- Rope combinations can also be supplied.

The most economical drive to use up to 50 H. P., is a high starting torque motor connected to the pinion shaft by means of a flat or V-Rope drive. For larger size motors the wound rotor (slip ring) is recommended due to its low current requirement in starting up the ball mill.

Should you be operating your own power plant or have D. C. current, please specify so that there will be no confusion as to motor characteristics. If switches are to be supplied, exact voltage to be used should be given.

Even though many ores require fine grinding for maximum recovery, most ores liberate a large percentage of the minerals during the first pass through the grinding unit. Thus, if the free minerals can be immediately removed from the ball mill classifier circuit, there is little chance for overgrinding.

This is actually what has happened wherever Mineral Jigs or Unit Flotation Cells have been installed in the ball mill classifier circuit. With the installation of one or both of these machines between the ball mill and classifier, as high as 70 per cent of the free gold and sulphide minerals can be immediately removed, thus reducing grinding costs and improving over-all recovery. The advantage of this method lies in the fact that heavy and usually valuable minerals, which otherwise would be ground finer because of their faster settling in the classifier and consequent return to the grinding mill, are removed from the circuit as soon as freed. This applies particularly to gold and lead ores.

Ball-Rod Mills have heavy rolled steel plate shells which are arc welded inside and outside to the steel heads or to rolled steel flanges, depending upon the type of mill. The double welding not only gives increased structural strength, but eliminates any possibility of leakage.

Where a single or double flanged shell is used, the faces are accurately machined and drilled to template to insure perfect fit and alignment with the holes in the head. These flanges are machined with male and female joints which take the shearing stresses off the bolts.

The Ball-Rod Mill Heads are oversize in section, heavily ribbed and are cast from electric furnace steel which has a strength of approximately four times that of cast iron. The head and trunnion bearings are designed to support a mill with length double its diameter. This extra strength, besides eliminating the possibility of head breakage or other structural failure (either while in transit or while in service), imparts to Ball-Rod Mills a flexibility heretofore lacking in grinding mills. Also, for instance, if you have a 5 x 5 mill, you can add another 5 shell length and thus get double the original capacity; or any length required up to a maximum of 12 total length.

On Type A mills the steel heads are double welded to the rolled steel shell. On type B and other flanged type mills the heads are machined with male and female joints to match the shell flanges, thus taking the shearing stresses from the heavy machine bolts which connect the shell flanges to the heads.

The manhole cover is protected from wear by heavy liners. An extended lip is provided for loosening the door with a crow-bar, and lifting handles are also provided. The manhole door is furnished with suitable gaskets to prevent leakage.

The mill trunnions are carried on heavy babbitt bearings which provide ample surface to insure low bearing pressure. If at any time the normal length is doubled to obtain increased capacity, these large trunnion bearings will easily support the additional load. Trunnion bearings are of the rigid type, as the perfect alignment of the trunnion surface on Ball-Rod Mills eliminates any need for the more expensive self-aligning type of bearing.

The cap on the upper half of the trunnion bearing is provided with a shroud which extends over the drip flange of the trunnion and effectively prevents the entrance of dirt or grit. The bearing has a large space for wool waste and lubricant and this is easily accessible through a large opening which is covered to prevent dirt from getting into the bearing.Ball and socket bearings can be furnished.

Scoop Feeders for Ball-Rod Mills are made in various radius sizes. Standard scoops are made of cast iron and for the 3 size a 13 or 19 feeder is supplied, for the 4 size a 30 or 36, for the 5 a 36 or 42, and for the 6 a 42 or 48 feeder. Welded steel scoop feeders can, however, be supplied in any radius.

The correct size of feeder depends upon the size of the classifier, and the smallest feeder should be used which will permit gravity flow for closed circuit grinding between classifier and the ball or rod mill. All feeders are built with a removable wearing lip which can be easily replaced and are designed to give minimum scoop wear.

A combination drum and scoop feeder can be supplied if necessary. This feeder is made of heavy steel plate and strongly welded. These drum-scoop feeders are available in the same sizes as the cast iron feeders but can be built in any radius. Scoop liners can be furnished.

The trunnions on Ball-Rod Mills are flanged and carefully machined so that scoops are held in place by large machine bolts and not cap screws or stud bolts. The feed trunnion flange is machined with a shoulder for insuring a proper fit for the feed scoop, and the weight of the scoop is carried on this shoulder so that all strain is removed from the bolts which hold the scoop.

High carbon steel rods are recommended, hot rolled, hot sawed or sheared, to a length of 2 less than actual length of mill taken inside the liners. The initial rod charge is generally a mixture ranging from 1.5 to 3 in diameter. During operation, rod make-up is generally the maximum size. The weights per lineal foot of rods of various diameters are approximately: 1.5 to 6 lbs.; 2-10.7 lbs.; 2.5-16.7 lbs.; and 3-24 lbs.

Forged from the best high carbon manganese steel, they are of the finest quality which can be produced and give long, satisfactory service. Data on ball charges for Ball-Rod Mills are listed in Table 5. Further information regarding grinding balls is included in Table 6.

Rod Mills has a very define and narrow discharge product size range. Feeding a Rod Mill finer rocks will greatly impact its tonnage while not significantly affect its discharge product sizes. The 3.5 diameter rod of a mill, can only grind so fine.

Crushers are well understood by most. Rod and Ball Mills not so much however as their size reduction actions are hidden in the tube (mill). As for Rod Mills, the image above best expresses what is going on inside. As rocks is feed into the mill, they are crushed (pinched) by the weight of its 3.5 x 16 rods at one end while the smaller particles migrate towards the discharge end and get slightly abraded (as in a Ball Mill) on the way there.

We haveSmall Ball Mills for sale coming in at very good prices. These ball mills are relatively small, bearing mounted on a steel frame. All ball mills are sold with motor, gears, steel liners and optional grinding media charge/load.

Ball Mills or Rod Mills in a complete range of sizes up to 10 diameter x20 long, offer features of operation and convertibility to meet your exactneeds. They may be used for pulverizing and either wet or dry grindingsystems. Mills are available in both light-duty and heavy-duty constructionto meet your specific requirements.

All Mills feature electric cast steel heads and heavy rolled steelplate shells. Self-aligning main trunnion bearings on large mills are sealedand internally flood-lubricated. Replaceable mill trunnions. Pinion shaftbearings are self-aligning, roller bearing type, enclosed in dust-tightcarrier. Adjustable, single-unit soleplate under trunnion and drive pinionsfor perfect, permanent gear alignment.

Ball Mills can be supplied with either ceramic or rubber linings for wet or dry grinding, for continuous or batch type operation, in sizes from 15 x 21 to 8 x 12. High density ceramic linings of uniform hardness male possible thinner linings and greater and more effective grinding volume. Mills are shipped with liners installed.

Complete laboratory testing service, mill and air classifier engineering and proven equipment make possible a single source for your complete dry-grinding mill installation. Units available with air swept design and centrifugal classifiers or with elevators and mechanical type air classifiers. All sizes and capacities of units. Laboratory-size air classifier also available.

A special purpose batch mill designed especially for grinding and mixing involving acids and corrosive materials. No corners mean easy cleaning and choice of rubber or ceramic linings make it corrosion resistant. Shape of mill and ball segregation gives preferential grinding action for grinding and mixing of pigments and catalysts. Made in 2, 3 and 4 diameter grinding drums.

Nowadays grinding mills are almost extensively used for comminution of materials ranging from 5 mm to 40 mm (3/161 5/8) down to varying product sizes. They have vast applications within different branches of industry such as for example the ore dressing, cement, lime, porcelain and chemical industries and can be designed for continuous as well as batch grinding.

Ball mills can be used for coarse grinding as described for the rod mill. They will, however, in that application produce more fines and tramp oversize and will in any case necessitate installation of effective classification.If finer grinding is wanted two or three stage grinding is advisable as for instant primary rod mill with 75100 mm (34) rods, secondary ball mill with 2540 mm(11) balls and possibly tertiary ball mill with 20 mm () balls or cylpebs.To obtain a close size distribution in the fine range the specific surface of the grinding media should be as high as possible. Thus as small balls as possible should be used in each stage.

The principal field of rod mill usage is the preparation of products in the 5 mm0.4 mm (4 mesh to 35 mesh) range. It may sometimes be recommended also for finer grinding. Within these limits a rod mill is usually superior to and more efficient than a ball mill. The basic principle for rod grinding is reduction by line contact between rods extending the full length of the mill, resulting in selective grinding carried out on the largest particle sizes. This results in a minimum production of extreme fines or slimes and more effective grinding work as compared with a ball mill. One stage rod mill grinding is therefore suitable for preparation of feed to gravimetric ore dressing methods, certain flotation processes with slime problems and magnetic cobbing. Rod mills are frequently used as primary mills to produce suitable feed to the second grinding stage. Rod mills have usually a length/diameter ratio of at least 1.4.

Tube mills are in principle to be considered as ball mills, the basic difference being that the length/diameter ratio is greater (35). They are commonly used for surface cleaning or scrubbing action and fine grinding in open circuit.

In some cases it is suitable to use screened fractions of the material as grinding media. Such mills are usually called pebble mills, but the working principle is the same as for ball mills. As the power input is approximately directly proportional to the volume weight of the grinding media, the power input for pebble mills is correspondingly smaller than for a ball mill.

A dry process requires usually dry grinding. If the feed is wet and sticky, it is often necessary to lower the moisture content below 1 %. Grinding in front of wet processes can be done wet or dry. In dry grinding the energy consumption is higher, but the wear of linings and charge is less than for wet grinding, especially when treating highly abrasive and corrosive material. When comparing the economy of wet and dry grinding, the different costs for the entire process must be considered.

An increase in the mill speed will give a directly proportional increase in mill power but there seems to be a square proportional increase in the wear. Rod mills generally operate within the range of 6075 % of critical speed in order to avoid excessive wear and tangled rods. Ball and pebble mills are usually operated at 7085 % of critical speed. For dry grinding the speed is usually somewhat lower.

The mill lining can be made of rubber or different types of steel (manganese or Ni-hard) with liner types according to the customers requirements. For special applications we can also supply porcelain, basalt and other linings.

The mill power is approximately directly proportional to the charge volume within the normal range. When calculating a mill 40 % charge volume is generally used. In pebble and ball mills quite often charge volumes close to 50 % are used. In a pebble mill the pebble consumption ranges from 315 % and the charge has to be controlled automatically to maintain uniform power consumption.

In all cases the net energy consumption per ton (kWh/ton) must be known either from previous experience or laboratory tests before mill size can be determined. The required mill net power P kW ( = ton/hX kWh/ton) is obtained from

Trunnions of S.G. iron or steel castings with machined flange and bearing seat incl. device for dismantling the bearings. For smaller mills the heads and trunnions are sometimes made in grey cast iron.

The mills can be used either for dry or wet, rod or ball grinding. By using a separate attachment the discharge end can be changed so that the mills can be used for peripheral instead of overflow discharge.

major mines & projects | north mara mine

The North Mara Mine is situated within the Mara Greenstone Belt. The underlying geology comprises felsic and mafic volcanics intercalated with sediments which are intruded by various granitoid and gabbroic plutonic rocks. Tertiary volcanic lava flows partially cover the underlying Archaean geology and the ore bodies are structurally controlled, shear-hosted lode gold deposits. There are several types of gold mineralisation including shear-zone-related quartz vein and disseminated gold.

The North Mara mine is currently an underground operation (Gokona). The North Mara transitioned to underground mining during 2020 and significant improvements made to improve costs and operational effectiveness.At Gokona, Acacia utilizes an existing exploration decline for initial access to the planned underground mine. Two major declines are included in the mine plan. The mining method utilised in the operation is Long Hole Open Stoping (LHOS) with Cemented Aggregate Fill (CAF).

The ore is hauled in 80 tonne dump trucks up to the Run of Mine (ROM) pad at Nyabirama. The ore is drawn out of the ROM bin and fed onto a vibrating grizzly screen by means of an apron feeder. The undersize material passes through the grizzly onto a conveyor belt while the oversize material passes through a jaw crusher which discharges onto the same conveyor belt. The ore is fed onto a banana screen via a two tier conveyor system. The undersize from the banana screen passes onto a conveyor belt which feeds the SAG (Semi-Autogenous Grinding) mill feed stockpile while the oversize material is fed into a secondary cone crusher. The crushed ore from the secondary stockpile is tipped onto the SAG feed stockpile.The ore is drawn from underneath the SAG mill feed stockpile onto the SAG mill feed conveyor belt by means of three vibrating feeders. It is fed into the SAG mill for primary grinding. The SAG mill discharge is pumped to a cluster of twelve cyclones for classification. The cyclone overflow is fed to two trash screens whilst the underflow reports to a scalping screen prior to gravity concentration. Screen overflow is recombined with gravity circuit tails and reports to 2 ball mills in closed circuit with the classification cyclones.

Gravity separationACACIA reactorCarbon re-activation kilnConcentrate leachAgitated tank (VAT) leachingCounter current decantation (CCD)Carbon in leach (CIL)AARL elutionSolvent Extraction & ElectrowinningCyanide (reagent)

Both oxide and sulphide reserves are mined and processed by conventional carbon-in-leach (CIL) technology. The concentrate from the Knelson Concentrators is fed to the Acacia reactor in the gold room for gold recovery by intensive cyanidation. Acacia tailings are returned to the ball mill circuit and pregnant solution is pumped to electrowinning cells.The trash screen overflow falls into a bunker whilst the underflow is fed to two thickeners. Thickened slurry is pumped to the CIL circuit and water recovered from the thickeners is pumped back to the mill circuit as process water. The CIL circuit consists of three pre-leach tanks and nine adsorption tanks. Carbon is transferred counter current to slurry flow by means of air lifts and is pumped from Tank 4 over the loaded carbon screen before being transferred to the acid wash section.Residue from the CIL section is pumped to a cyanide detoxification circuit where Weak Acid Dissociable (WAD) cyanide con ........

major mines & projects | borden mine

Owing to its metamorphic grade, the Borden Gold deposit is markedly different from most known Archean-aged mesothermal gold occurrences. On the basis of visual evidence, which is yet to be supported by detailed petrographic studies, it is believed that the Borden Gold deposit is most closely associated with the disseminated gold sub-class. The gold mineralization at the Borden Gold deposit occurs as a broad zone of disseminated and fracture-controlled sulphides within a volcano- metasedimentary package of variable composition. The main sulphides are pyrite and pyrrhotite, with the former typically dominating. The mineralization generally consists of low- to moderate-grade gold, with minor silver, and is characterized by a persistent higher-grade core surrounded by a lower-grade envelope. Results to date indicate that the higher-grade core improves in grade towards the southeast where it develops into a High-Grade Zone (HGZ) with average grades typically above 2.5 g/t Au. The northwest portions of the deposit are characterized by local silicification but lack lithological control and quartz veining; while to the southeast a well-developed hydrothermal system consisting of local quartz flooding and potassic alteration predominates and defines the HGZ. The broad mineralized zone encompasses multiple/variable host rocks, dominated by metasedimentary horizons and subordinate intrusives of acidic to intermediate composition, all of which display feldspathic, chloritic and biotitic alteration. Outcropping in the northwest parts of the deposit, the lower-grade mineralization rarely exhibits visible gold grains, while in the southeast HGZ it is much more common, particularly in the quartz-rich core. A higher-grade core is also consistently present within the lower-grade zone, locally attaining very high grades reminiscent of the HGZ.The deposit displays continuity and is consistently intersected along strike, reaching a current length of 3.7 kilometres, while remaining open in both the northwest and southeast directions. Structurally, the deposit is described by a consistent northeast dip and, locally, a shallow southeast plunge, which is mostly evident in the HGZ. Mineralization appears to be controlled by a ductile shear zone, which appears much better developed in the HGZ. The mineralized zone is up to 120 m wide, and has been confirmed to a vertical depth of approximately 650 m.

Borden mine is the worlds first all-electric underground mine.Commercial gold production at Borden began in October 2019.The Borden Gold Mine has an ore production capacity of 4000 tonnes per day over a mine life of up to 15 years.Mining method: - Sub-level retreat- Cemented rock fill with waste backhaul from PGM for waste requirement.- 15m longhole retreat factored 24% dilution - ~2000tpd ore @ 7gpt to mill using proven production rates- 5x5m main haulage drifts- Diesel trucks & tethered (electric) scoops until quick-charge battery alternate is viable. - Battery electric equipment.Overall, the best fit for Borden was a fleet comprised of equipment from Sandvik and MacLean. Scoops: Sandvik LH 514 E tethered electric Trucks: Sandvik TH 54-0 diesel - with a firm commitment to a 40 T battery truck Drills: Sandvik DD 422i Bolters: MacLean MEM 975 Scissor Bolter Utility Vehicles: MacLean Cassette Carries and Scissor Lift Grader: MacLean conversion of a Cat 12 M2 diesel grader.

Gravity separationSmeltingACACIA reactorAgitated tank (VAT) leachingConcentrate leachCarbon in pulp (CIP)Carbon adsorption-desorption-recovery (ADR)ElutionSolvent Extraction & ElectrowinningCyanide (reagent)

Ore from Borden is processed at the existing Dome mill.Gold is recovered using a combination of gravity concentration and cyanidation techniques. The circuit consists of primary, secondary and tertiary crushing, rod/ball mill grinding, gravity concentration, cyanide leaching, carbon-in-pulp gold recovery, stripping, electro winning and refining.Gravity gold is recovered by the use of five Knelson CD-30 Concentrators fed from the cyclone underflow. A Consep CS6000 Acacia Reactor is used to intensively leach the Knelson concentrate. The Acacia loaded solution has a dedicated electrowinning circuit. Gravity recovery accounts for up to 45% of the recovered gold, depending on ore type.The cyclone overflows reports to a 155' thickener where the slurry density is increased to 55-60% solids. The thickener underflow feeds six leach tanks in series, which provide about 32 hours residence time.Lime is added to the mill discharge pump boxes, thickene ........

ball mills | industry grinder for mineral processing - jxsc machine

Max Feeding size <25mm Discharge size0.075-0.4mm Typesoverflow ball mills, grate discharge ball mills Service 24hrs quotation, custom made parts, processing flow design & optimization, one year warranty, on-site installation.

Ball mill, also known as ball grinding machine, a well-known ore grinding machine, widely used in the mining, construction, aggregate application. JXSC start the ball mill business since 1985, supply globally service includes design, manufacturing, installation, and free operation training. Type according to the discharge type, overflow ball mill, grate discharge ball mill; according to the grinding conditions, wet milling, dry grinding; according to the ball mill media. Wet grinding gold, chrome, tin, coltan, tantalite, silica sand, lead, pebble, and the like mining application. Dry grinding cement, building stone, power, etc. Grinding media ball steel ball, manganese, chrome, ceramic ball, etc. Common steel ball sizes 40mm, 60mm, 80mm, 100mm, 120mm. Ball mill liner Natural rubber plate, manganese steel plate, 50-130mm custom thickness. Features 1. Effective grinding technology for diverse applications 2. Long life and minimum maintenance 3. Automatization 4. Working Continuously 5. Quality guarantee, safe operation, energy-saving. The ball grinding mill machine usually coordinates with other rock crusher machines, like jaw crusher, cone crusher, to reduce the ore particle into fine and superfine size. Ball mills grinding tasks can be done under dry or wet conditions. Get to know more details of rock crushers, ore grinders, contact us!

Ball mill parts feed, discharge, barrel, gear, motor, reducer, bearing, bearing seat, frame, liner plate, steel ball, etc. Contact our overseas office for buying ball mill components, wear parts, and your mine site visits. Ball mill working principle High energy ball milling is a type of powder grinding mill used to grind ores and other materials to 25 mesh or extremely fine powders, mainly used in the mineral processing industry, both in open or closed circuits. Ball milling is a grinding method that reduces the product into a controlled final grind and a uniform size, usually, the manganese, iron, steel balls or ceramic are used in the collision container. The ball milling process prepared by rod mill, sag mill (autogenous / semi autogenous grinding mill), jaw crusher, cone crusher, and other single or multistage crushing and screening. Ball mill manufacturer With more than 35 years of experience in grinding balls mill technology, JXSC design and produce heavy-duty scientific ball mill with long life minimum maintenance among industrial use, laboratory use. Besides, portable ball mills are designed for the mobile mineral processing plant. How much the ball mill, and how much invest a crushing plant? contact us today! Find more ball mill diagram at ball mill PDF ServiceBall mill design, Testing of the material, grinding circuit design, on site installation. The ball grinding mill machine usually coordinates with other rock crusher machines, like jaw crusher, cone crusher, get to know more details of rock crushers, ore grinders, contact us! sag mill vs ball mill, rod mill vs ball mill

How many types of ball mill 1. Based on the axial orientation a. Horizontal ball mill. It is the most common type supplied from ball mill manufacturers in China. Although the capacity, specification, and structure may vary from every supplier, they are basically shaped like a cylinder with a drum inside its chamber. As the name implies, it comes in a longer and thinner shape form that vertical ball mills. Most horizontal ball mills have timers that shut down automatically when the material is fully processed. b. Vertical ball mills are not very commonly used in industries owing to its capacity limitation and specific structure. Vertical roller mill comes in the form of an erect cylinder rather than a horizontal type like a detachable drum, that is the vertical grinding mill only produced base on custom requirements by vertical ball mill manufacturers. 2. Base on the loading capacity Ball mill manufacturers in China design different ball mill sizes to meet the customers from various sectors of the public administration, such as colleges and universities, metallurgical institutes, and mines. a. Industrial ball mills. They are applied in the manufacturing factories, where they need them to grind a huge amount of material into specific particles, and alway interlink with other equipment like feeder, vibrating screen. Such as ball mill for mining, ceramic industry, cement grinding. b. Planetary Ball Mills, small ball mill. They are intended for usage in the testing laboratory, usually come in the form of vertical structure, has a small chamber and small loading capacity. Ball mill for sale In all the ore mining beneficiation and concentrating processes, including gravity separation, chemical, froth flotation, the working principle is to prepare fine size ores by crushing and grinding often with rock crushers, rod mill, and ball mils for the subsequent treatment. Over a period of many years development, the fine grinding fineness have been reduced many times, and the ball mill machine has become the widest used grinding machine in various applications due to solid structure, and low operation cost. The ball miller machine is a tumbling mill that uses steel milling balls as the grinding media, applied in either primary grinding or secondary grinding applications. The feed can be dry or wet, as for dry materials process, the shell dustproof to minimize the dust pollution. Gear drive mill barrel tumbles iron or steel balls with the ore at a speed. Usually, the balls filling rate about 40%, the mill balls size are initially 3080 cm diameter but gradually wore away as the ore was ground. In general, ball mill grinder can be fed either wet or dry, the ball mill machine is classed by electric power rather than diameter and capacity. JXSC ball mill manufacturer has industrial ball mill and small ball mill for sale, power range 18.5-800KW. During the production process, the ball grinding machine may be called cement mill, limestone ball mill, sand mill, coal mill, pebble mill, rotary ball mill, wet grinding mill, etc. JXSC ball mills are designed for high capacity long service, good quality match Metso ball mill. Grinding media Grinding balls for mining usually adopt wet grinding ball mills, mostly manganese, steel, lead balls. Ceramic balls for ball mill often seen in the laboratory. Types of ball mill: wet grinding ball mill, dry grinding ball mill, horizontal ball mill, vibration mill, large ball mill, coal mill, stone mill grinder, tumbling ball mill, etc. The ball mill barrel is filled with powder and milling media, the powder can reduce the balls falling impact, but if the power too much that may cause balls to stick to the container side. Along with the rotational force, the crushing action mill the power, so, it is essential to ensure that there is enough space for media to tumble effectively. How does ball mill work The material fed into the drum through the hopper, motor drive cylinder rotates, causing grinding balls rises and falls follow the drum rotation direction, the grinding media be lifted to a certain height and then fall back into the cylinder and onto the material to be ground. The rotation speed is a key point related to the ball mill efficiency, rotation speed too great or too small, neither bring good grinding result. Based on experience, the rotat

ion is usually set between 4-20/minute, if the speed too great, may create centrifuge force thus the grinding balls stay with the mill perimeter and dont fall. In summary, it depends on the mill diameter, the larger the diameter, the slower the rotation (the suitable rotation speed adjusted before delivery). What is critical speed of ball mill? The critical speed of the ball mill is the speed at which the centrifugal force is equal to the gravity on the inner surface of the mill so that no ball falls from its position onto the mill shell. Ball mill machines usually operates at 65-75% of critical speed. What is the ball mill price? There are many factors affects the ball mill cost, for quicker quotations, kindly let me know the following basic information. (1) Application, what is the grinding material? (2) required capacity, feeding and discharge size (3) dry or wet grinding (4) single machine or complete processing plant, etc.

major mines & projects | hoyle pond mine

The Hoyle Pond Main Zone and 1060 Zone deposits occur on opposite limbs of an open, northeast-plunging antiformal structure, hosted within carbonatized north-dipping tholeiitic basalts. The 7 Vein System occurs as a series of stacked, flat to gently northeast-dipping veins in the nose of the antiformal structure.The Hoyle Pond Main Zone includes a series of generally northeast-striking, linked, quartz vein zones folded on a small scale with moderate west- and northeast-plunging axes.The 1060 Zone consists of at least five main vein structures (1060 B1, B2 and B3 zones, A zone and Porphyry zone) with orientations ranging from north to northeast and a generally subvertical dip. The veins are strongly boudinaged, with the long axis of the boudin oriented from subhorizontal to shallow westsouthwest plunging.AlterationThe mineralization at Hoyle Pond occurs as coarse free gold in white to greywhite quartz veins with a variable ankerite, tourmaline, pyrite, and locally arsenopyrite, content. Alteration halos are generally narrow, consisting of mainly grey zones (carbon, carbonate, sericite, cubic pyrite) in the Hoyle Pond system and carbonatesericite, plus fuchsite with pyrite, arsenopyrite and trace amounts of chalcopyrite and sphalerite within the 1060 structure.Gold at the Hoyle Pond Mine predominantly occurs as coarse free gold in white to greyishwhite quartz veins with variable ankerite, tourmaline, pyrite, pyrrhotite and local arsenopyrite. Trace amounts of chalcopyrite and sphalerite have also been noted.The Hoyle Pond Main Zone includes a series of generally northeast-striking, linked quartz vein zones. There are at least 11 veins of economic significance. These veins are folded on a small scale with moderate west and northeast plunging axes. The 1060 zone consists of at least five main vein structures with orientations ranging from north to northeast, are strongly boudinaged, and generally have a subvertical dip.A series of auriferous zones occurs along what is termed the South Trend, stretching from the Bell Creek deposit (to the west of Hoyle Pond) for 6.4 km to the 1060 zone (includes BlackhawkVogel deposit, Owl Creek West, Owl Creek, Owl Creek East and the 950 zone). Mineralization in these zones consists of quartzankerite veining with varying amounts of pyrite, pyrrhotite and free gold.

Access to the underground workings is by means of two ramps, one at either end of the ore body and a four-compartment shaft.The Hoyle Pond mine hosts a variety of ore shapes. In order to maximize the stoping efficiency, numerous stoping methods are used.Conventional cut and fill, shrinkage and panel mining methods are typically employed to excavate the narrower gold bearing vein structures. Each of the preceding mining methods is used to extract vein structures with vertical and/or near horizontal attitudes. Veins mined by these methods typically range from 0.20 meters to 2.0 meters thick and are usually higher grade material. Mucking is accomplished using appropriately sized slushers.Longhole methods with paste backfilling are used in wider stoping areas. Longhole levels are advanced at 60 meter intervals with sub levels at a 20 m interval. Haulage drifts are driven in the footwall about 12 meters offset from the ore zone. Backfilling methods were traditionally a combination of rock fill and cemented slag but these methods have been replaced with high quality paste backfill delivered through holes from surface and distributed with a network of underground piping.

Gravity separationACACIA reactorSmeltingConcentrate leachAgitated tank (VAT) leachingCarbon in pulp (CIP)Carbon adsorption-desorption-recovery (ADR)ElutionSolvent Extraction & ElectrowinningCyanide (reagent)

Ore from Hoyle Pond is processed at the existing Dome mill.Gold is recovered using a combination of gravity concentration and cyanidation techniques. The circuit consists of primary, secondary and tertiary crushing, rod/ball mill grinding, gravity concentration, cyanide leaching, carbon-in-pulp gold recovery, stripping, electro winning and refining.Gravity gold is recovered by the use of five Knelson CD-30 Concentrators fed from the cyclone underflow. A Consep CS6000 Acacia Reactor is used to intensively leach the Knelson concentrate. The Acacia loaded solution has a dedicated electrowinning circuit. Gravity recovery accounts for up to 45% of the recovered gold, depending on ore type.The cyclone overflows reports to a 155' thickener where the slurry density is increased to 55-60% solids. The thickener underflow feeds six leach tanks in series, which provide about 32 hours residence time.Lime is added to the mill discharge pump boxes, thic ........

winston gold updates progress at paradine mill facility | winston gold corp

WINNIPEG, MB / ACCESSWIRE / April 21, 2021 / Winston Gold Corp. (Winston Gold or the Corporation) (CSE:WGC)(OTCQB:WGMCF)is pleased to announce that it currently has 30 tons of flotation concentrate ready for shipment to a refinery. An additional 10 tons of concentrate will be ready to ship once necessary upgrades are completed at the Paradine Mill Facility, near Radersburg Montana.

Until Winston leased the Paradine mill, it lay idle for 20 years, commented Murray Nye, CEO and Director of Winston Gold Mines. The overall advantages of renovating an old mill significantly outweigh building and permitting a new one. In just eight months, we have completed numerous upgrades to make the Paradine mill reliable and efficient.

It was recently discovered that the trunnion bearings in the ball mill needed to be replaced. This will keep the mill out of operation for about 30 days. Winston Gold will take advantage of this down-time to continue to streamline the mill by inspecting and repairing minor issues that have been identified with the primary flotation cells and the installation of a set of cleaner cells to further improve gold and silver recoveries.

About the Paradine Mill Facility The Paradine Mill located just 35 miles (56 km) by paved road from the Companys wholly owned Winston Gold project which is situated near Helena, Montana. The Mill has a nameplate capacity of 150 tons per day and hosts a ball milling circuit as well as both a gravity and flotation circuit. A new lined settling pond has been constructed for tailings disposal with a 35,000-ton capacity and two additional ponds are also being built.

Qualified Person The scientific and technical content and interpretations contained in this news release have been reviewed, verified and approved by Dr. Criss Capps PhD. P.Geol., an independent consultant to Winston Gold Corp. Dr. Capps is a Qualified Person as defined in National Instrument 43-101 Standards of Disclosure for Mineral Projects.

About Winston Gold Winston Gold is a junior mining company focused on advancing high-grade, low-cost mining opportunities into production. Towards that end, the Corporation has acquired the under-explored and under-exploited Winston Gold project near Helena, Montana.

The CSE has neither approved nor disapproved the information contained herein. This news release does not constitute an offer to sell or a solicitation of an offer to buy any of the securities in the United States. The securities have not been and will not be registered under the United States Securities Act of 1933, as amended (the U.S. Securities Act), or any state securities laws and may not be offered or sold within the United States or to U.S. Persons unless registered under the U.S. Securities Act and applicable state securities laws or an exemption from such registration is available.

Forward-Looking Information This release includes certain statements that may be deemed forward-looking statements. All statements in this release, other than statements of historical facts, that address events or developments that Winston Gold Mining Corp. (the Company) expects to occur, are forward-looking statements. Forward-looking statements are statements that are not historical facts and are generally, but not always, identified by the words expects, plans, anticipates, believes, intends, estimates, projects, potential and similar expressions, or that events or conditions will, would, may, could or should occur. Although the Company believes the expectations expressed in such forward-looking statements are based on reasonable assumptions, such statements are not guarantees of future performance and actual results may differ materially from those in the forward-looking statements. Factors that could cause the actual results to differ materially from those in forward-looking statements include regulatory actions, market prices, exploitation and exploration successes, and continued availability of capital and financing, and general economic, market or business conditions. Investors are cautioned that any such statements are not guarantees of future performance and actual results or developments may differ materially from those projected in the forward-looking statements. Forward-looking statements are based on the beliefs, estimates and opinions of the Companys management on the date the statements are made. Except as required by applicable securities laws, the Company undertakes no obligation to update these forward-looking statements in the event that managements beliefs, estimates or opinions, or other factors, should change.

For more information, please visitwww.winstongoldmining.com; or contact: Murray Nye, Chief Executive Officer and a Director of Winston Gold Suite 201-919 Notre Dame Avenue Winnipeg, Manitoba, R3E 0M8 Telephone: (204) 989-2434 E-mail:[email protected]

professional gold industrial ball mill for wet / dry grinding 110kw

Professional Gold Industrial Ball Mill For Wet / Dry Grinding 110kw Gold Mining Ball Mill Introduction The ball mill with coarse particle product is common used in the first stage ore grinding. It is lined grooved ring plate which increases the contact surface of ball and ore and strengthens the grinding. Gold Mining Ball Mill Advantages 1. Large double row self-aligning roller, bearing with low friction force, is used to replace sliding bearing, which is easy to start and saves 20-30% energy. 2. It is lined grooved ring plate, which increases the contact surface of ball and ore and strengthens the grinding. 3. Large ore outlet and large capacity 4. The mill with diameter below 2.1 meters adopts whole machine frame, which is convenient for civil construction and equipment installation. 5. Oil mist lubrication device guarantees the lubrication of all gears. Gold Mining Ball Mill Working Principle The main part of ball mill is a cylinder with small diameter and large length rotating slowly by the transmission device. In wet grinding, material is taken out; in dry grinding, the material is taken out by air. The grid installed in the outlet of mill is relied for forced discharge. Both ends of the cylinder body adopt rolling bearing instead of the sliding bearing, which is more energy-saving. Technical Data: Model Effective volume (m3) Max. steel ball load (t) Capacity (t/h) Power (kW) Rotary speed(rpm) Weight (t) MQG MQY MQS MQG MQY MQS 15003000 4.8 6.6 8.3 10 4.3-8 8.6-16 10-19 75 29 15 15004500 7.1 10 12 15 6.5-12 13-24 15-28 110 29 18 15005700 9 13 16 19 8.2-15 16-31 19-35 130 29 24 Ball Mill Working Site:

The ball mill with coarse particle product is common used in the first stage ore grinding. It is lined grooved ring plate which increases the contact surface of ball and ore and strengthens the grinding.

The main part of ball mill is a cylinder with small diameter and large length rotating slowly by the transmission device. In wet grinding, material is taken out; in dry grinding, the material is taken out by air. The grid installed in the outlet of mill is relied for forced discharge. Both ends of the cylinder body adopt rolling bearing instead of the sliding bearing, which is more energy-saving.

winston gold upgrades to paradine mill facility nearing completion | winston gold corp

WINNIPEG, MB / ACCESSWIRE / June 4, 2021 /Winston Gold Corp. (Winston Gold or the Corporation) (CSE:WGC) (OTCQB:WGMCF)is pleased to announce that the necessary upgrades to the Paradine Mill Facility, near Radersburg, Montana, are nearing completion, despite staffing, material acquisition and delivery challenges.

Naturally, with any re-commissioning activity, unforeseen challenges inevitably arise, commented Mr. Murray Nye, CEO and Director of Winston Gold Corp. I must commend our staff at the Paradine Mill facility for their perseverance and dedication during this period. The overall advantages of renovating an old mill still significantly outweigh building and permitting a new one.

Work at the mill is now focused on installing critical new parts (delayed due to shipping issues), in addition to re-configuring and optimizing the floatation circuits. The following points summarize the progress achieved to date:

The Paradine mill facility is being developed into a turn-key mineral processing plant, stated Mr. Joseph Carrabba, Executive Chairman of Winston Gold. The mill lies in the heart of a region blessed with precious metal endowment, and the future value opportunities are significant.

Towards that end, Winston Gold recently formed a joint venture with Bond Resources (CSE:BJB) to test the near-term cash-flow viability of another past producer, the Hard Cash Mine.(Refer to news release dated May 13th2021). The Hard Cash property is located just 4.3 miles from the Paradine Mill and an initial drill program should commence shortly.

The Paradine mill located just 35 miles (56 km) by paved road from the Companys wholly owned Winston Gold project which is situated near Helena, Montana. The Mill has a nameplate capacity of 150 tons per day and hosts a ball milling circuit as well as both a gravity and flotation circuit. A new lined settling pond has been constructed for tailings disposal with a 35,000-ton capacity and two additional ponds are also being built.

The scientific and technical content and interpretations contained in this news release have been reviewed, verified and approved by Dr. Criss Capps PhD. P.Geol., an independent consultant to Winston Gold Corp. Dr. Capps is a Qualified Person as defined in National Instrument 43-101 Standards of Disclosure for Mineral Projects.

Winston Gold is a junior mining company focused on advancing high-grade, low-cost mining opportunities into production. Towards that end, the Corporation has acquired the under-explored and under-exploited Winston Gold project near Helena, Montana.

The CSE has neither approved nor disapproved the information contained herein. This news release does not constitute an offer to sell or a solicitation of an offer to buy any of the securities in the United States. The securities have not been and will not be registered under the United States Securities Act of 1933, as amended (the U.S. Securities Act), or any state securities laws and may not be offered or sold within the United States or to U.S. Persons unless registered under the U.S. Securities Act and applicable state securities laws or an exemption from such registration is available.

This release includes certain statements that may be deemed forward-looking statements. All statements in this release, other than statements of historical facts, that address events or developments that Winston Gold Mining Corp. (the Company) expects to occur, are forward-looking statements. Forward-looking statements are statements that are not historical facts and are generally, but not always, identified by the words expects, plans, anticipates, believes, intends, estimates, projects, potential and similar expressions, or that events or conditions will, would, may, could or should occur. Although the Company believes the expectations expressed in such forward-looking statements are based on reasonable assumptions, such statements are not guarantees of future performance and actual results may differ materially from those in the forward-looking statements. Factors that could cause the actual results to differ materially from those in forward-looking statements include regulatory actions, market prices, exploitation and exploration successes, and continued availability of capital and financing, and general economic, market or business conditions. Investors are cautioned that any such statements are not guarantees of future performance and actual results or developments may differ materially from those projected in the forward-looking statements. Forward-looking statements are based on the beliefs, estimates and opinions of the Companys management on the date the statements are made. Except as required by applicable securities laws, the Company undertakes no obligation to update these forward-looking statements in the event that managements beliefs, estimates or opinions, or other factors, should change.

gold leaching equipment, circuits & process plants

In Leaching for Gold, there is often a tendency to overlook or minimize the importance of the small mine. The small mine of today may develop into the large mine of tomorrow. Under proper management and financing it has as good a chance of yielding a profit as the larger property. Unfortunately large capital is seldom interested in them and they are left to the small groups who are not in a position to obtain the best engineering service. Mills are often erected without proper metallurgical tests and expensive Gold Leachingplant equipment are installed at a time when such large expenditures of capital on the surface is not justified by the underground developments. Careful metallurgical testing on the ore might have disclosed the fact that a simple method of amalgamation or concentration could have been employed and the mill built for a third the cost of a Gold Leaching plant.

By taking advantage of the fact that gold is one of the heaviest metals known and readily forms an amalgam with mercury, an effective but simple and inexpensive plant can be built for most small gold mines. Usually the major percentage of the gold values are in the native or metallic state and are free at commercial fineness of grinding and can be recovered by some combination of amalgamation and concentration.

Plate amalgamation, where the gold values are caught and held in the quicksilver film on a copper plate is the only step required for a commercial recovery on some few ores. In most cases a portion of the gold is filmed so that it does not amalgamate readily or is contained in ores with other minerals that also amalgamate or foul the quicksilver sufficiently to destroy its effectiveness for gold recovery. Here a form of selective concentration such as the Mineral Jigs and blanket tables, is used to concentrate the gold values in a small bulk of high grade concentrates for treatment in an amalgamation barrel or other amalgamator, where the gold is amalgamated and recovered as bullion.

The advantages of these simple plants are many and are not only attractive to the proved small mine but also to those under development. Within recent years many of our well known mines have been developed and brought into large scale production from revenue secured from a small milling plant operating on development ore.

A study of a large number of mills using amalgamation and concentration has disclosed bullion recoveries ranging from 60 per cent to 90 per cent and total recoveries, including concentrates, from 85 per cent to 97 per cent. The average bullion recovery will be about 70 per cent and very often this is of utmost importance as geographic location makes the shipping of the concentrate to a smelting plant undesirable.

While cyanidation is usually favored for treating gold ores to get maximum recovery of the values in bullion form, nevertheless, the fact that an amalgamation plantcan be built for approximately one- third of a complete Gold Leaching mill, together with the lower operating costs of the simpler plant, partially offsets the lower recovery. It is customary to impound the tailings from the amalgamation plant and these are cheaply treated when mine developments have justified the erection of the more complete Gold Leachingplant. An amalgamation and concentration plant can be operating intermittently without sacrificing efficiency, and this allows the operation of the plant for only one or two shifts per day to keep the peak power requirements at a minimum as mine compressors can be operated or the hoisting done while the mill is not in operation. The fact that 60 to 90 per cent of the values can be recovered by amalgamation will usually supply sufficient revenue from the mill to pay for development charges andbuild a reserve for the construction of the complete Gold Leaching plant.

With reasonable care in the design and construction of the original amalgamation and concentration plant all of the equipment can be utilized in the later complete Gold Leaching mill. By using standard equipment it is possible to add the Gold Leaching equipment following the already installed amalgamation and concentration units as these are an essential part of the completed plant.

Other advantages of these simple and inexpensive amalgamation and concentration plants are that they can be successfully operated with unskilled labor as no chemical knowledge or previous experience is necessary. Even flotation has been simplified through the use of Sub-A Flotation Cells; this addition of flotation means no marked increase in milling costs, but often a large increase in recovery due to the saving of extremely fine mineral values.

It is interesting to note the numerous dividend paying gold properties, particularly those in Eastern Canada, which have followed the treatment methods shown in the following flowsheets during the development stage and they have gradually added to the equipment as the profits and ore developments warranted. The use of standard proved equipment eliminates the biggest element of chance, and from this nucleus a more efficient and complete plant can be acquired as the flexibility of the equipment permits the change from one flowsheet to another.

We are giving five typical flowsheets used in treating gold ores and are describing the possible applications of these flowsheets, together with their fields of usefulness, and while in each case there is a similarity in equipment, you will note the changes necessary for various type ores. In each case we have endeavored to show the simplest possible plant for best results on each type of ore and to show the improvements that can be made to further increase recoveries at slight additional cost.

This flowsheet is the lowest in price, and can be used on what are commonly termed as free milling gold ores where a high percentage of the values are free and where these values are unlocked at reasonably coarse grinding.This flowsheet is often used for treating high grade pockets. The ball mill is in open circuit and the size of the product to amalgamation plates is controlled by a Spiral Screen on the ball mill discharge. The concentrating table also functions as a classifier and the middling is returned as oversize product for further grinding.

Flowsheet BB has a Mineral Jig and amalgamator in addition to the equipment shown for Flowsheet AA, and is used for an inexpensive plant where values are coarse but minerals are coated or filmed, and will not amalgamate readily on plates. The jig recovers the rusty values in a high grade concentrate for forcedamalgamation treatment in the Amalgamator. Onthe ores where this flowsheet is applicable, blankets, corduroy, or Gold Matting are usually substituted for amalgamation plates and their concentrate also is treated in the amalgamator with the jig product.

This flowsheet with the ball mill in closed circuit with a classifier, and with the jig in this circuit, will give the highest recovery possible for amalgamation and gravity concentration. The addition of the classifier allows finer grinding and the efficiency of the jig is greatly increased by using it in the closed grinding circuit. This flowsheet not only improves recoveries on ores as described in the previous flowsheets, but is also useful where the minerals are fine and where metallic values are in auriferous sulphides as well as in the free state in the gangue.

The addition of flotation to Flowsheet CC brings recovery to the highest point in Flowsheet DD as flotation recovers the slime values that are normally lost where gravity concentration only is used. The values that can be amalgamated are secured in bullion form from the high grade jig and table concentrates, and the remaining values are recovered in the flotation concentrate. This flowsheet is also necessary where a minor percentage of the gold values are present as metallics at commercial fineness of grinding or where the minerals are friable and easily slimed in fine grinding such as galena or the various telluride minerals.

The addition of flotation does not increase greatly the first cost of the plant, nor does it increase the operating expenses more than a few cents per ton. In a great many cases the additional recovery made by flotation means the difference between operating at a profit and at a loss. Flotation is responsible for the success of many small mining properties today.

Where the isolated location of the mill makes shipping of concentrates prohibitive, many properties store their product until they are justified in installing a complete treatment plant on the ground; current expenses are thus paid through bullion recovered by amalgamation ahead of flotation.

The equipment in this flowsheet is identical to that of DD. Here the ability of the Sub-A Flotation Machine to effectively handle a coarse feed is capitalized on to allow the handling of greatly increased tonnages. The ball mill discharge passes in open circuit over the jig, amalgamation plates or blanket tables and the flotationmachine. A middling product is returned from theconcentrating table and is dewatered in the classifier and returned for regrinding. On tailings, dumps, or low grade ores where it is necessary to handle a larger tonnage, this flowsheet is very effective, and while the recoveries would not be as high as in Flowsheet DD, the loss in recovery is more than offset by the greatly increased tonnage handled and the resultant lower milling cost. With this flowsheet a coarse tailing can be discarded, but slime losses are entirely eliminated as these, together with the granular minerals, are recovered in the flotation machine.

This flexibility of flowsheet is possible only where the Sub-A Flotation Machine is used. The (Selective) Mineral Jig is a valuable addition here as the excessive dilution would make it impossible to use any other type of gravity concentration device ahead of flotation. The change from Flowsheet DD to Flowsheet EE can be very easily made to accommodate changes in ore and to allow greater profits from the treatment of any type gold ore encountered.

No two ores are exactly alike. What method of treatment will give you the greatest net profit in milling your ore? This can be determined by proper metallurgical tests. They will show the recoveries which may be obtained by various methods of treatment; and the type and cost of equipment required, and the operating cost for each method are then easily established.

Ore tests are conducted on the basis of obtaining the simplest possible flowsheet, using standard, proved equipment. Also, as you will note in the flowsheets shown, this fundamental principle is always followed: Recover the mineral as soon as it is free.

A study of a large number of mills using amalgamation and concentration has disclosed bullion recoveries ranging from 60 per cent to 90 per cent and total recoveries, including concentrates, from 85 per cent to 97 per cent. The average bullion recovery will be about 70 per cent and very often this is of utmost importance as geographic location makes the shipping of the concentrate to a smelting plant undesirable.

While cyanidation is usually favored for treating gold ores to get maximum recovery of the values in bullion form, nevertheless, the fact that an amalgamation plant can be built for approximately one-third of a complete cyanide mill, together with the lower operating costs of the simpler plant, partially offsets the lower recovery. It is customary to impound the tailings from the amalgamation plant and these are cheaply treated when mine developments have justified the erection of the more complete cyanide plant. An amalgamation and concentration plant can be operating intermittently without sacrificing efficiency, and this allows the operation of the plant for only one or two shifts per day to keep the peak power requirements at a minimum as mine compressors can be operated or the hoisting done while the mill is not in operation. The fact that 60 to 80 per cent of the values can be recovered by amalgamation will usually supply sufficient revenue from the mill to pay for development charges and build a reserve for the construction of the complete cyanide plant.

With reasonable care in the design and construction of the original amalgamation and concentration plant all of the equipment can be utilized in the later complete cyanide mill. By using standard equipment it is possible to add the cyanide equipment following the already installed amalgamation and concentration units as these are an essential part of the completed plant.

Other advantages of these simple and inexpensive amalgamation and concentration plants are that they can be successfully operated with unskilled labor as no chemical knowledge or previous experience is necessary. Gold ore bodies can be accurately sampled by milling all of the ore from mine development work and the errors resulting from ordinary sampling methods can be entirely eliminated.

It is interesting to note the numerous dividend paying gold properties, particularly those in Eastern Canada, which have followed the treatment methods shown in the following flowsheets during the development stage and they have gradually added to the equipment as the profits and ore developments warranted. The use of standard proved equipment eliminates the biggest element of chance, and from this nucleus a more efficient and complete plant can be acquired as the flexibility of the equipment permits the change from one flowsheet to another.

We are giving four typical flowsheets used in treating gold ores and are describing the possible applications of these flowsheets, together with their fields of usefulness, and while in each case there is a similarity in equipment, you will note the changes necessary for various type ores. In each case we have endeavoured to show the simplest possible plant for best results on each type of ore and to show the improvements that can be made to further increase recoveries at slight additional cost.

This flowsheet is the lowest in price, and can be used on what are commonly termed as free milling gold ores where a high percentage of the values are free and where these values are unlocked at reasonably coarse grinding. This flowsheet is often used for treating high grade pockets. The ball mill is in open circuit and the size of the product to amalgamation plates is controlled by a Spiral Screen on the ball mill discharge. The concentrating table also functions as a classifier and the middling is returned as oversize product for further grinding.

Flowsheet BB has a Mineral Jig and amalgamator in addition to the equipment shown for Flowsheet AA, and is used for an inexpensive plant where values are coarse but minerals are coated or filmed, and will not amalgamate readily on plates. The jig recovers the rusty values in a high grade concentrate for forced amalgamation treatment in the Amalgamator. On the ores where this flowsheet is applicable, blankets, corduroy, or Gold Matting are usually substituted for amalgamation plates and their concentrate also is treated in the amalgamator with the jig product.

This flowsheet with the ball mill in closed circuit with a classifier, and with the jig in this circuit, will give the highest recovery possible for amalgamation and gravity concentration. The addition of the classifier allows finer grinding and the efficiency of the jig is greatly increased by using it in the closed grinding circuit. This flowsheet not only improves recoveries on ores as described in the previous flowsheets, but is alo useful where the minerals are fine and where metallic values are in auriferous sulphides as well as in the free state in the gangue.

The addition of flotation to Flowsheet CC brings recovery to the highest point in Flowsheet DD as flotation recovers the slime values that are normally lost where gravity concentration only is used. The values that can be amalgamated are secured in bullion form from the high grade jig and table concentrates, and the remaining values are recovered in the flotation concentrate. This flowsheet is also necessary where a minor percentage of the gold values are present as metallics at commercial fineness of grinding or where the minerals are friable and easily slimed in fine grinding such as galena or the various telluride minerals.

The addition of flotation does not increase greatly the first cost of the plant, nor does it increase the operating expenses more than a few cents per ton. In a great many cases the additional recovery made by flotation means the difference between operating at a profit and at a loss. Flotation is responsible for the success of many small mining properties today.

Where the isolated location of the mill makes shipping of concentrates prohibitive, many properties store their product until they are justified in installing a complete treatment plant on the ground; current expenses are thus paid through bullion recovered by amalgamation ahead of flotation. The equipment in this flowsheet is identical to that of DD. Here the ability of the Flotation Machine to handle a coarse feed is capitalized on to allow the handling of greatly increased tonnages. The ball mill discharge passes in open circuit over the jig, amalgamation plates or blanket tables and the flotation machine. A middling product is returned from the concentrating table and is dewatered in the classifier and returned for regrinding. On tailings, dumps, or low grade ores where it is necessary to handle a larger tonnage, this flowsheet is very effective, and while the recoveries would not be as high as in Flowsheet DD, the loss in recovery is more than offset by the greatly increased tonnage handled and the resultant lower milling cost. With this flowsheet a coarse tailing can be discarded, but slime losses are entirely eliminated as these, together with the granular minerals, are recovered in the flotation machine.

This flexibility of flowsheet is possible only where the standard Sub-A Type Flotation Machine is used. The Mineral Jig is a valuable addition here as the excessive dilution would make it impossible to use any other type of gravity concentration device ahead of flotation. The change from Flowsheet DD to Flowsheet EE can be very easily made to accommodate changes in ore and to allow greater profits from the treatment of any type gold ore encountered.

The 5 Gold Leaching Equipment Flowsheets illustrated above indicate the equipment essential for small cyanide mills of five different tonnages. These flowsheets are all similar with equipment sized for the tonnages shown. They are typical flowsheets for continuous counter-current decantation cyanidation plus a Mineral Jig in the grinding circuit with provisions for amalgamation of the jig concentrates.

The Mineral Jig and Amalgamation Unit have a definite place in cyanide plants as the coarse and granular gold can be readily recovered which may not be completely dissolved by the cyanide solution during the treatment time given to the pulp. The cyanide process has the advantage of producing precious metals in bullion form with the highest net return from those gold and silver ores amenable to cyanidation. The counter current decantation washing circuit has been found to be a most economical method for removing dissolved precious metals. Washing Tray Thickeners require the minimum floor space and capital costs. In counter current decantation wash water and barren solution are added in the last thickener units and flow counter to pulp flows, becoming enriched and are finally passed to clarification and precipitation where precious metals are precipitated and recovered.

The above flowsheets illustrate a method of increasing both capacity and recovery in a small gold plant by several stages. This is typical of the Pay As You Grow method of increasing capacity and profits essential in so many small operations. Because each ore has its own individual characteristics it is wise to first start with reliable test data. This is just as important in developing a flowsheet for a small mill as it is for a large plant.

Gold Flowsheet No. 1 shows a typical simple mill for the recovery of gold by amalgamation and by concentrating tables. However, on many ores such a flowsheet gives high losses of both fine gold and sulfide minerals.

Gold Flowsheet No. 3 indicates the addition of a required mill, classifier and extra Sub-A Flotation cells to provide for an increase in capacity and improvement in recoveries by regrinding of middling products.

Gold Flowsheet No. 4 shows an increase in flotation capacity to further improve recovery. The additions as illustrated allow an operation to be started on limited capital and gradually to be expanded as conditions warrant.

** Extracted from Memorandum Series No. 47, by C. S. Parsons, Engineer, Ore Dressing and Metallurgical Division, Mines Branch, Department of Mines, Ottawa. Published by permission of the Director, Mines Branch.

Source: This article is a reproduction of an excerpt of In the Public Domain documents held in 911Metallurgy Corps private library.[/fusion_builder_column][/fusion_builder_row][/fusion_builder_container]

small ball mills for sale

Our small-scale miners Ball Mills use horizontal rotating cylinders that contain the grinding media and the particles to be broken. The mass moves up the wall of the cylinder as it rotates and falls back into the toe of the mill when the force of gravity exceeds friction and centrifugal forces. Particles are broken in the toe of the mill when caught in the collisions between the grinding media themselves and the grinding media and the mill wall. In ball mills, the grinding media and particles acquire potential energy that becomes kinetic energy as the mass falls from the rotating shell. Ball mills are customarily divided into categories that are mainly defined by the size of the feed particles and the type of grinding media.

Intermediate and fine size reduction by grinding is frequently achieved in a ball mill in which the length of the cylindrical shell is usually 1 to 1.5 times the shell diameter. Ball mills of greater length are termed tube mills, and when hard pebbles rather than steel balls are used for the grinding media, the mills are known as pebble mills. In general, ball mills can be operated either wet or dry and are capable of producing products on the order of 100 um. This duty represents reduction ratios as great as 100.

The ball mill, an intermediate and fine-grinding device, is a tumbling drum with a 40% to 50% filling of balls. The material that is to be ground fills the voids between the balls. The tumbling balls capture the particles in ball/ball or ball/liner events and load them to the point of fracture. Very large tonnages can be ground with these devices because they are very effective material handling devices. The feed can be dry, with less than 3% moisture to minimize ball coating, or a slurry can be used containing 20% to 40% water by weight. Ball mills are employed in either primary or secondary grinding applications. In primary applications, they receive their feed from crushers, and in secondary applications, they receive their feed from rod mills, autogenous mills, or semi-autogenous mills. Regrind mills in mineral processing operations are usually ball mills, because the feed for these applications is typically quite fine. Ball mills are sometimes used in single-stage grinding, receiving crusher product. The circuits of these mills are often closed with classifiers at high-circulating loads.

All ball mills operate on the same principles. One of these principles is that the total weight of the charge in the mill-the sum of the weight of the grinding media, the weight of the material to be ground, and any water in the millis a function of the percentage of the volume of the mill it occupies.

The power the mill draws is a function of the weight of the charge in the mill, the %of volumetric loading of the mill, the %of critical speed, which is the speed in RPM at which the outer layer of the charge in the mill will centrifuge.

For closed grinding circuits producing typical ball mill products, indirect and direct on-line measurements of the product size are available. The indirect means are those which assume that the product size is relatively constant when the feed condition to the classifying unit and the operating conditions in the classifying unit are constant. One example is maintaining a constant mass flow, pulp density and pressure in the feed to the cyclone classifier.

By using math modeling, it is possible to calculate the product size from measured cyclone classifier feed conditions and circuit operating data, thus establishing the effect on the particle size distribution in the product for changes in the variables.

Direct on-line means to measure either particle size or surface area are available for typical ball mill circuit products. These require the means to obtain representative or at least consistent samples from the grinding circuit product stream. These direct means and the calculated product particle size distributions can be used to:

Small variations in the feed size to ball mill circuits generally is not critical to the calculation of operating work index because they make a very small change in the 10F factor. Thus, a computer program can be developed to calculate operating work indices from on-line data with the feed size a constant and with the program designed to permit manually changing this value, as required to take into account changes in feed size resulting from such things as drawing down feed bins, crusher maintenance, work screen surfaces in the crushing plant, etc. which are generally known in advance, or can be established quickly. Developments underway for on-line measurement of particle size in coarser material which when completed will permit measuring the feed size used to calculate operating work indices.

recorded by a data logger, gives continuous means to report comminution circuit performance and evaluate in-plant testing. Changes in Wio indicated on data loggers alert operating and supervisory personnel that a change has occurred in either the ore or in circuit performance. If sufficient instrumentation is available, the cause for a problem can often be located from other recorded or logged data covering circuit and equipment operation, however, generally the problem calls for operator attention to be corrected.

Wio can be used to determine the efficiency of power utilization for the entire comminution section of a mill, and for the individual circuits making up the comminution section. The efficiency of a comminution circuit is determined by the following equation.

Wi is obtained by running the appropriate laboratory tests on a composite sample of circuit feed. Wio is calculated from plant operating data covering the period when the feed sample was taken. Since Wi from laboratory tests refers to specific conditions for accurate efficiency determinations, it is necessary to apply correction factors as discussed in The Tools of Power Power to Wio to put the laboratory and operating data on the same basis.

To-date, there is no known way to obtain standard work index data from on-line tests. Continuous measurement of comminution circuit efficiency is not possible and thus efficiency is not available for circuit control. Using laboratory data and operating data, efficiency can be determined for overall section and individual circuit for evaluation and reporting. Just monitoring Wio and correcting operating problems as they occur will improve the utilization of the power delivered to the comminution circuits.

Samples taken from the chips around blast hole drillings and from broken ore in the pit or mine for laboratory work index and other ore characteristic determinations before the ore is delivered to the mill, can be used to predict in advance comminution circuit performance. Test results can also be used for ore blending to obtain a more uniform feed, particularly to primary autogenous and semi-autogenous circuits.

We sell Small Ball Mills from 2 to 6 (600 mm X 1800 mm) in diameter and as long as 10 (3000 mm) in length. The mills are manufactured using a flanged mild steel shell, cast heads, overflow discharge, removable man door, spur type ring gear, pinion gear assembly with spherical roller bearings, replaceable roller bronze trunnion bearings, oil lubrication, replaceable trunnion liners with internal spirals, rubber liners and lifters, feed spout with wash port, discharge trommel with internal spiral, motor and gear reducer drive, direct coupled to pinion gear, gear guard and modular steel support frame. All ball mills always come withOSHA-type gear guard.

A PULP level sufficiently high to interpose a bed of pulp, partly to cushion the impact of the balls, permits a maximum crushing effect with a minimum wear of steel. The pulp level of theseSmall Ball Millscan be varied from discharging at the periphery to discharging at a point about halfway between the trunnion and the periphery.The mill shell is of welded plate steel with integral end flanges turned for perfect alignment, and the heads are semi-steel, with hand holes in the discharge end through which the diaphragm regulation is arranged with plugs.The trunnion bearings are babbitted, spherical, cast iron, and of ample size to insure low bearing pressure; while the shell and saddle are machined to gauge so that the shells are interchangeable.

Data based on:Wet grinding, single stage, closed circuit operation: feed:( one way dimension); Class III ore. All mills:free discharge, grated type, rapid pulp flow. N. B.for overflow type mills: capacity 80%power 83%. Dimensions :diameters inside shell without linerslengths working length shell between end liners.

The CIW is a Small Ball Mill thats belt driven, rigid bearing, wet grinding, trunnion or grate discharge type mill with friction clutch pulley and welded steel shell. The 7 and 8 foot diameter mills are of flange ring construction with cut gears while all other sizes have cast tooth gears. All these mills are standard with white iron bar wave type shell liners except the 8 foot diameter mill which is equipped with manganese steel liners. The horsepowers shown in the table are under running conditions so that high torque or wound rotor (slip ring) motors must be used. Manganese or alloy steel shell or head liners and grates can be supplied with all sizes of mills if required. Alloy steel shell liners are recommended where 4 or larger balls are used and particularly for the larger sized mills.

Small (Muleback Type) Ball Mill is built for muleback transportation in 30 and 3 diameters (inside liners). A 4 (Muleback Type) Ball Mill is of special design and will be carefully considered upon request. Mankinds search for valuable minerals often leads him far away from modern transportation facilities. The potential sources of gold, silver and strategic minerals are often found by the prospector, not close by our modern highways, but far back in the mountains and deserts all over the world. The Equipment Company has realized this fact, and therefore has designed a Ball Mill that can be transported to these faraway and relatively inaccessible properties, either by the age old muleback transportation system, or by the modern airplane. As a result these properties may now obtain a well-designed ball mill with the heaviest individual piece weighing only 350 pounds.

The prime factor considered in this design was to furnish equipment having a maximum strength with a minimum weight. For this reason, these mills are made of steel, giving a high tensile strength and light weight to the mills. The muleback design consists of the sturdy cast iron head construction on the 30 size and cast steel head construction on the larger sizes. The flanges on the heads are arranged to bolt to the rolled steel shell provided with flanged rings. When required, the total length of the shell may consist of several shell lengths flanged together to provide the desired mill length. Liners, bearings, gears and drives are similar to those standard on all Ball Mills.

This (Convertible) and Small Ball Mill is unique in design and is particularly adapted to small milling plants. The shell is cast in one piece with a flange for bolting to the head. In converting the mill from a 30x 18 to a 30x 36 unit with double the capacity, it is only necessary to secure a second cast shell (a duplicate of the first) and bolt it to the original section.

30 Convertible Ball Mills are furnished with scoop feeders with replaceable lips. Standard mills are furnished with liners to avoid replacement of the shell; however, themill can be obtained less liners. This ball mill is oftendriven by belts placed around the center, although gear drive units with cast gears can be furnished. A Spiral Screen can be attached to the discharge.

This mill may be used for batch or intermittent grinding, or mixing of dry or wet materials in the ore dressing industry, metallurgical, chemical, ceramic, or paint industries. The material is ground and mixed in one operation by rotating it together with balls, or pebbles in a hermetically sealed cylinder.

The cast iron shell which is bolted to the heads is made with an extra thick wall to give long wearing life. Two grate cleanout doors are provided on opposite sides of the shell by means of which the mill can be either gradually discharged and washed, while running, or easily and rapidly emptied and flushedout while shut down. Wash-water is introduced into the interior of the mill through a tapped opening in the trunnion. The mill may be lined with rubber, silex (buhrstone) or wood if desired.

The Hardinge Conical Ball Mill has been widely used with outstanding success in grinding many materials in a wide variety of fields. The conical mill operates on the principle of an ordinary ball mill with a certain amount of classification within the mill itself, due to its shape.

Sizes of conical mills are given in diameter of the cylindrical section in feet and the length of the cylindrical section in inches. Liners can be had of hard iron, manganese steel or Belgian Silex. Forged steel balls or Danish Flint Pebbles are used for the grinding media, depending upon the material being milled.

The Steel Head Ball-Rod Mill gives the ore dressing engineer a wide choice in grinding design so that he can easily secure a Ball-Rod Mill suited to his particular problem. The successful operation of any grinding unit is largely dependent on the method of removing the ground pulp. The Ball-Rod Mill is available with five types of discharge trunnions, each type obtainable in small, medium or large diameters. The types of discharge trunnions are:

The superiority of the Steel Head Ball-Rod Mill is due to the all steel construction. The trunnions are an integral part of the cast steel heads and are machined with the axis of the mill. The mill heads are assured against breakage due to the high tensile strength of cast steel as compared to that of the cast iron head found on the ordinary ball mill. Trunnion Bearings are made of high- grade nickel babbitt.

Steel Head Ball-Rod Mills can be converted intolarger capacity mills by bolting an additional shell lengthonto the flange of the original shell. This is possible because all Steel Head Ball or Rod Mills have bearings suitable for mills with length twice the diameter.

Head and shell liners for Steel Head Ball-Rod Mills are available in Decolloy (a chrome-nickel alloy), hard iron, electric steel, molychrome steel, and manganese steel. Drive gears are furnished either in cast tooth spur gear and pinion or cut tooth spur gear and pinion. The gears are furnished as standard on the discharge end of the mill, out of the way of the classifier return feed, but can be furnished at the mill feed end by request. Drives may be obtained according to the customers specifications.

Thats one characteristic of Traylor Ball Millsliked by ownersthey are built not only to do a first class job at low cost but to keep on doing it, year after year. Of course, that means we do not build as many mills as if they wore out quicklyor would we? but much as welike order, we value more the fine reputationTraylor Ball Mills have had for nearly threedecades.

Thats one characteristic of Traylor Ball Mills We dont aim to write specifications into thisliked by ownersthey are built not only to do advertisementlet it suffice to say that theresa first class job at low cost but to keep on do- a Traylor Ball Mills that will exactly fit anyanything it, year after year. Of course, that means requirement that anyone may have.

If this is true, there is significance in the factthat international Nicked and Climax Molybdenum, theworlds largest producers of two important steel alloys, areboth users of MARCY Mills exclusively. With international interest centered on increasingproduction of gold, it is even more significant that MARCYMills are the predominant choice of operators in everyimportants gold mining camp in the world.

Ball Mill. Intermediate and fine size reduction by grinding is frequently achieved in a ball mill in which the length of the cylindrical shell is usually 1 to 1.5 times the shell diameter. Ball mills of greater length are termed tube mills, and when hard pebbles rather than steel balls are used for the grinding media, the mills are known as pebble mills. In general, ball mills can be operated either wet or dry and are capable of producing products on the order of 100 pm. This duty represents reduction ratios as great as 100.

The ball mill, an intermediate and fine-grinding device, is a tumbling drum with a 40% to 50% filling of balls (usually steel or steel alloys). The material that is to be ground fills the voids between the balls. The tumbling balls capture the particles in ball/ball or ball/liner events and load them to the point of fracture. Very large tonnages can be ground with these devices because they are very effective material handling devices. The feed can be dry, with less than 3% moisture to minimize ball coating, or a slurry can be used containing 20% to 40% water by weight. Ball mills are employed in either primary or secondary grinding applications. In primary applications, they receive their feed from crushers, and in secondary applications, they receive their feed from rod mills, autogenous mills, or semiautogenous mills. Regrind mills in mineral processing operations are usually ball mills, because the feed for these applications is typically quite fine. Ball mills are sometimes used in single-stage grinding, receiving crusher product. The circuits of these mills are often closed with classifiers at high-circulating loads.

These loads maximize throughput at a desired product size. The characteristics of ball mills are summarized in the Table, which lists typical feed and product sizes. The size of the mill required to achieve a given task-that is, the diameter (D) inside the liners-can be calculated from the design relationships given. The design parameters must be specified.

The liner- and ball-wear equations are typically written in terms of an abrasion index (Bond 1963). The calculated liner and ball wear is expressed in kilograms per kilowatt-hour (kg/kWh), and when multiplied by the specific power (kWh/t), the wear rates are given in kilograms per ton of feed. The wear in dry ball mills is approximately one-tenth of that in wet ball mills because of the inhibition of corrosion. The efficiency of ball mills as measured relative to single-particle slow-compression loading is about 5%. Abrasion indices for five materials are also listed in the Table.

The L/D ratios of ball mills range from slightly less than 1:1 to something greater than 2:1. The tube and compartment ball mills commonly used in the cement industry have L/D ratios 2.75:1 or more. The fraction of critical speed that the mill turns depends on the application, and most mills operate at around 75% of critical speed. Increased speed generally means increased power, but as the simulations presented in Figure 3.26 show, it can also produce more wasted ball impacts on the liners above the toe. causing more wear and less breakage.

There are three principal forms of discharge mechanism. In the overflow ball mill, the ground product overflows through the discharge end trunnion. A diaphragm ball mill has a grate at thedischarge end. The product flows through the slots in the grate. Pulp lifters may be used to discharge the product through the trunnion, or peripheral ports may be used to discharge the product.

The majority of grinding balls are forged carbon or alloy steels. Generally, they are spherical, but other shapes have been used. The choice of the top (or recharge) ball size can be made using empirical equations developed by Bond or Azzaroni or by using special batch-grinding tests interpreted in the content of population balance models. The effect of changes in ball size on specific selection functions has been found to be different for different materials. A ball size-correction method can be used along with the specific selection function scale-up method to determine the best ball size. To do this, a set of ball size tests are performed in a batch mill from which the specific selection function dependence on ball size can be determined. Then, the mill capacities used to produce desired product size can be predicted by simulation using the kinetic parameter corresponding to the different ball sizes.

The mill liners used are constructed from cast alloy steels, wear-resistant cast irons, or polymer (rubber) and polymer metal combinations. The mill liner shapes often recommended in new mills are double-wave liners when balls less than 2.5 in. are used and single-wave liners when larger balls are used. Replaceable metal lifter bars are sometimes used. End liners are usually ribbed or employ replaceable lifters.

The typical mill-motor coupling is a pinion and gear. On larger mills two motors may be used, and in that arrangement two pinions drive one gear on the mill. Synchronous motors are well suited to the ball mill, because the power draw is almost constant. Induction, squirrel cage, and slip ring motors are also used. A high-speed motor running 600 to 1,000 rpm requires a speed reducer between the motor and pinion shaft. The gearless drive has been installed at a number of locations around the world.

what are the differences between ball mill and rod mill? | fote machinery

Ball mill and rod mill are the common grinding equipment applied in the grinding process. They are similar in appearance and both of them are horizontal cylindrical structures. Their cylinders are equipped with grinding medium, feeder, gears, and transmission device.

The working principle of ball mill and rod mill machine is similar, too. That is, the cylinder drives the movement of the grinding medium (lifting the grinding medium to a certain height then dropping). Under the action of centrifugal force and friction, the material is impacted and ground to required size, so as to realize the operation of mineral grinding.

Grate discharge ball mill can discharge material through sieve plate, with the advantage of the low height of the discharge port which can make the material pass quickly so tha t to avoid over-grinding of material. Under the same condition, it has a higher capacity and can save more energy than other types of mills;

It is better to choose a grate discharge ball mill when the required discharge size is in the range of 0.2 to 0.3 mm. Grate discharge ball mill is usually applied in the first grinding system because it can discharge the qualified product immediately.

Overflow discharge ball mill can grind ores into the size under 0.2 mm, so it is very suitable for the second grinding system. The capacity of it is about 15% lower than grate discharge ball mill in the same specification, and the loaded grinding medium is also less than that one.

It can be divided into three types of rod mills according to the discharge methods, center and side discharge rod mill, end and side discharge rod mill and shaft neck overflow discharge rod mill.

It is fed through the shaft necks in the two ends of rod mill, and discharges ore pulp through the port in the center of the cylinder. Center and side discharge rod mill can grind ores coarsely because of its structure.

This kind of rod mill can be used for wet grinding and dry grinding. "A rod mill is recommended if we want to properly grind large grains, because the ball mill will not attack them as well as rod mills will."

It is fed through one end of the shaft neck, and with the help of several circular holes, the ore pulp is discharged to the next ring groove. The rod mill is mainly used for dry and wet grinding processes that require the production of medium-sized products.

The diameter of the shaft neck is larger than the diameter of the feeding port about 10 to 20 centimeters, so that the height difference can form a gradient for ore pulp flow. There is equipped with a spiral screen in the discharge shaft neck to remove the impurities.

It has high toughness, good manufacturability and low price. The surface layer of high manganese steel will harden rapidly under the action of great impact or contact. The harder index is five to seven times higher than other materials, and the wear resistance is greatly improved.

It has high toughness, good manufacturability and low price. The surface layer of high manganese steel will harden rapidly under the action of great impact or contact. The harder index is five to seven times higher than other materials, and the wear resistance is greatly improved.

It is made of several elements such as chromium and molybdenum, which has high hardness and good toughness. Under the same work condition, the service of this kind of ball is one time longer than the high manganese steel ball.

After the professional technology straightening and quenching processing process, a high carbon steel rod has high hardness, excellent performance, good wear resistance and outstanding quality.

The steel ball of ball mill and the mineral material are in point contact, so the finished product has a high degree of fineness, but it is also prone to over-grinding. Therefore, it is suitable for the production with high material fineness and is not suitable for the gravity beneficiation of metal ores.

The steel rod and the material are in line or surface contact, and most of the coarse particles are first crushed and then ground. Therefore, the finished product is uniform in quality, excellent in particle size, and high in qualification rate.

The cylinder shape of the rod mill and the ball mill is different: the cylinder of the rod mill is a long type, and the floor area is large. The ratio of the length to the diameter of the cylinder is generally 1.5 to 2.0;

The cylinder of the ball mill is a barrel or a cone. And the ratio of the length to the diameter of the cylinder is small, and in most cases the ratio is only slightly larger than 1, and the floor area is small, too.

The above is the main content of this article. The ball mill and the rod mill are the same type of machine on the appearance, but there are still great differences in the interior. It is very necessary to select a suitable machine for the production to optimize the product effect and maximize its efficiency.

As a leading mining machinery manufacturer and exporter in China, we are always here to provide you with high quality products and better services. Welcome to contact us through one of the following ways or visit our company and factories.

Based on the high quality and complete after-sales service, our products have been exported to more than 120 countries and regions. Fote Machinery has been the choice of more than 200,000 customers.

grinding mills

Common types of grinding millsinclude Ball Mills and Rod Mills. This includes all rotating mills with heavy grinding media loads. This article focuses on ball and rod mills excluding SAG and AG mills. Although their concepts are very similar, they are not discussed here.

As the mill revolves, lifters assist in picking up the grinding charge and elevate it to an angle at which gravity overcomes friction and centrifugal force. The charge then cascades downward, effectively grinding particles of material within the mill by continuous, repeated impact and attrition action.

Grinding Mill speed is one of the factors affecting the character of the cascading charge. As shown in the illustrations, the lower the percentage of critical speed, the smoother the flow of balls from top of charge to bottom. Higher percentage of critical speed is used for impact grinding of large feed. Lower percentage of critical speed is used for attrition grinding when a fine product is desired. The graph belowwill be helpful in determining percentage of critical speed when internal mill diameter and RPMare known. A Grinding Mill is a revolving cylinder loaded to approximately one-half its volume with steel rods, balls or pebbles.

Grinding mills reduce particle size by impact, rolling and sliding. Of the many types in use, the cylindrical mill, which employs a cascading mass of balls or rods, is universally used for the size reduction of hard, moderate to highly abrasive materials, such as minerals, ores, stone, and chemicals. ,

A cylindrical mill, when operating under uniform conditions, will produce a uniform product. Wear on grinding surfaces has little effect on capacity or product size. Very little maintenance is required with these mills, downtime being a negligible factor in their operation. For continuity of operation, the cylindrical mill has no equal.

Grinding mills of this type will give you dependable, trouble-free operation year after year, with planned periods of stoppage for renewal of parts. Initial cost is distributed over a long operating period. Many grinding mills are still in service after more than 40 years of almost continuous operation. Ton for ton of material handled, the cylindrical type mill has proved to be the most economical investment for reducing moderate to extremely abrasive materials.

911Metallurgist sourcesmanufacturers of all the proven mill designs in a small range of sizes your assurance of getting the most suitable mill for your purpose. Best grinding efficiency and economy can be obtained only when the type and size of your mill is matched with your grinding job. Mills can also be furnished with modifications to suit any special application.

The choice between wet or dry grinding is dependent upon the use of the product or the subsequent process. It is imperative to dry grind many materials because of physical or chemical changes which occur if water or a solution are added. Wet grinding with water (or with a concentrated solution of the soluble salts being ground) is generally preferred, because of the overall economies of this operation.

Another factor in choosing a grinding mill is the consideration of the feed size introduced into the mill, and the product required from the mill or mill circuit. This can be best illustrated by comparing two prevailing and diametrically opposite grinds.

In the manufacture of standard cement by grinding cement clinker, the clinker is reduced from 1 or finer down to a specific surface of 1750 sq cm per gram. This area can be produced by an open or closed circuit grind. The specific area method (which indicates the square centimeters of surface exposed per gram of material ground) is a most satisfactory method of determining whether a cement product will meet an accepted standard.

In a typical cement plant employing closed circuit grinding, 1750 surface can be obtained with a finish grind of between 93 and 96% passing 200 mesh. This arearequirement means that fines are not only desirable but necessary, and that a size analysis must show a distribution of material from approximately 80 microns down to less than one micron.

When grinding ore prior to concentration, on the other hand, the grind is determined by the degree of reduction necessary to unlock the valuable mineral from the gangue. This gangue is undesirable and must be separated from the desired material. For example, the full-size illustration above shows a piece of coarse-grained magnetite. The grind necessary to unlock the magnetite is about 14 mesh. At this grind, almost every individual crystal of iron oxideis freed from associated gangue and the ground material is ready for magnetic concentration.

Actually then, the ideal grind would be to reduce this ore down to 14 mesh particlesnot finer, for any expenditure of energy to reduce this ore beyond the unlocking mesh size is wasted. Such a grind is impossible, but any grinding circuit should be controlled so as to minimize overgrinding. Some fine material is produced, but it is tolerated rather than desired.

The product resulting from the reduction of a number of particles is dependent on two distinct shapes of grinding mediathe rod and the ball. Here the term ball is used to cover the entire range of grinding media which is spherical in shape, or roughly so.

The principle of grinding action, rods as compared to balls, can be best understood by making a comparison of their contact with adjacent rods or balls. Rods making up a grinding charge are nearly parallel and tend to meet adjacent rods in line contact. Rods tend to bear only on the largest particles, thereby expending most of their crushing force on the over-size and allowing the fine particles a freer passage between the rods without being ground to objectionable fineness. Balls, on the other hand, meet adjacent balls in point contact and particles of material at these points are ground to a very fine state.

Concavex grinding medium is an improved type of ball grinding media which offers more surface area per unit of weight, and has found extensive use in the grinding of cement clinker. The advantage of Concavex medium is its ability to increase mill capacity because of its interlocking shape and increased density per cubic foot of grinding charge. Surface areas for Concavex grinding media are given later.

Ball mills are built in Overflow and Diaphragm types. In the Overflow mill the material is discharged by new feed moving into the mill and displacing a mixture of solids and water being ground within the mill. The diaphragm arrangement in a ball mill is a positive means of pumping pulp or dry material out of the mill. The gradient is steeper than in an Overflow type mill. A Diaphragm ball mill has a higher capacity and requires more power than an Overflow ball mill of equal ball charge.

The Overflow rod mill is applied to wet grinding. The Center Peripheral Discharge rod mill is also used for wet grinding but produces a coarser product than the overflow type. Either the End or Center Peripheral discharge rod mill can be used for wet or dry grinding. Whatever the type, the rod mill is used to produce a coarse product, whereas the ball mill is used to produce a finer product.

Should a ball mill grind be required, the relationship of the length to the diameter of the mill is important. Feed and product screen analyses, and the type of circuit (openor closed), dictate the proper diameter to length ratio of a mill.

The type of mill for a particular grind and the circuit in which it is to be used must be considered simultaneously. Circuits are divided into two broad classifications, open and closed. In open circuit, the material is fed into the mill at a rate calculated to produce the correct finished product in one pass through the mill. This circuit has been popular in the cement and chemical industries, although the present trend is toward closed circuit installations. The closed circuit is generally employed in the mineral dressing industry.

In the closed circuit the material is discharged from the mill into a classifying device. The classifier separates and (1) returns the oversize material to the mill for further grinding, (2) delivers the fine material as finished product of that circuit. Material returning to the mill is called circulating load, and the ratio of this material to new feed may vary from a few percent to 600 percent or more.

Several types of separators are used in closed circuit grinding. Vibrating screens with screen cloth as fine as 28 mesh are used to produce a mesh product from either wet or dry grinding circuits. Fine wet grinding circuits employa classifier to separate a product varying from 10 to 325 mesh. Fine dry grinding circuits employ an air separator for products of 65 mesh and finer.

In open circuit grinding the feed rate must be low enough to permit a longer retention time per particle within the mill. This assures that each particle of the incoming feed, however large, will be broken down to product size. As a result, many particles in the product are ground to sub-sieve size. In ore dressing, these fine particles are usually undesirable, and the additional power required to produce them is a wasted expenditure. However, sub-sieve size particles are sometimes desirable, where the properties of the finished material require it. Finished cement and pottery glaze are examples of products requiring fines in the micron sizes.

In a closed circuit operation no effort is made to produce all the reduction during a single pass through the mill. Instead, every effort is made to remove a particle from the circuit as soon as it reaches the required product size. Quite often one of the largest particles of the feed, partiallyreduced, will be discharged, separated and returned to the mill several times before being completely reduced to the desired size.

Open circuits are particularly useful where simplicity of the layout may be a determining factor . . . where a product containing ultra-fines is preferred or where the material does not lend itself to handling in any classifying device.

All foregoing references to open and closed circuits apply to the ball mill. Because of the action of its grinding media, many rod mills are operated in open circuit, especially when preparing feed for ball mills. The rod mill, due to the character of its parallel grinding surfaces, simulates a slotted screen. The screening effect in the mill tends to retard the larger particles until reduced. Smaller particles slip through spaces between rods and are discharged without appreciable reduction.

Due to many variables, grinding is considered an art, not a science. A number of factors which affect grinding capacity are so variable that considerable engineering experience is required for a judicious selection of the propermill and circuit for a given operation.

Some operators prefer the high speed mill, others will consider only grinding mills operating at low speeds. Grinding mill speed, it should be noted, is not absolute, not a definite rpm, but relative to a quantity called critical speed.

The critical speed of a mill is defined as the lowest rpm necessary to centrifuge an infinitely small particle next to the shell lining within the mill. By equation: where CS=Critical speed in rpm. D=Internal diameter of mill inside the shell lining, in feet.

Allis-Chalmers recognizes these, as well as other factors influencing HPrequirements, and has developed an equation for calculating mill HP. This equation, as applied to dry grinding diaphragm ball mills, is as follows:

HP=HP per ft of mill length. W=Weight of grinding charge and material per ft of mill length. C=Distance in feet from center of mill to the center of gravity of the grinding media. a=Dynamic angle of repose of grinding charges, usually 43 for dry grinding slow speed ball mill, 51 for normal ball mill speeds.

The dynamic angle of repose, a, is impossible to determine, and is calculated from the equation by substitution of all other factors. Once determined for a set of conditions, angle a can be substituted in the formula for any horsepower calculation. The horsepower so obtained is sufficient to cover fractional losses in the bearings and drive.

From quantity (W) of the equation, it is obvious that the mill horsepower is proportional to the apparent density of the grinding media. Also, mill horsepower is proportional to the angle of repose of the grinding media. Thats why Concavex grinding media increases a mills horsepower. Concavex media has a slightly greater apparent density. Because of its shape, it interlocks more than balls, resulting in a higher angle of repose.

The equation shown in the graph below will be helpful in determining the percent charge in specific mills, knowing Q (see Fig. 4). A definite charge percent and weight can be calculated for a desired value of Q, or the distance below the mill centerline (Q-D).

One of the oldest; and most reliable methods of determining the horsepower-hours required per unit of grinding capacity is to get comparable information from an existing operation which is grinding a similar material to the same grind.

To select a mill size by this method, it is therefore essential to have laboratory grindability results on a large number of commercially ground materials and to have this grinding data in considerable detail.

We havetabulated results of grindability tests covering a wide variety of materials and product specifications of commercially ground materials. These test results are a reliable guide in relating the grinding characteristics ofyour material to a material that is being ground in an existing operation.

Weemploy two methods of determining a materials resistance to grinding. One is made by grinding to a specific mesh size. The grindability index, G, is expressed as grams produced with a definite percentage of circulating load.

The other method is applicable to materials ground inthe cement and chemical industries, where no specific meshsize may be required, but a definite surface area must beproduced. Essentially, this test simulates an open circuitby grinding the sample in a ball mill until 85 percent passes20 mesh. The ball mill product is further ground in a jarmill until 92 percent passes 200 mesh. Index I is derivedfrom the product screen analvsis plot of the ball mill test:

Occasionally a test is requested on a material for which field data does not exist. The grindability test is still useful, but it is recommended that a verifying pilot plant test be made when a large operation is planned.

In recent years, rod mills have found increasing use in preparing ball mill feed. The rod mill is exceptionally well suited to handle coarse feed and to control the top size of the product. Rod mill products are generally coarser than those produced in a ball mill. Because of these characteristics, the rod mill has also found wide acceptance by manufacturers of fine concrete aggregates, where rigid state or federal specifications must be met.

Rod mills are also used extensively in the grinding of chemicals, coke, limestone, slag, etc. It has been a general practice to build rod mills in lengths of 10 to 12 feet. This permits the use of rods of sufficient length to perform screening action, retarding the passage of oversize particles through the mill until reduced to product size and finer.

Where a finely divided product must not be adulterated by iron, the pebble mill is the logical choice. These mills are lined with a non-metallic material such as porcelain or stone, and employ flint or stone grinding bodies. Thus, iron contamination caused by grinding is kept to a minimum. This is an important consideration in the glass sand, scouring powder, talc, and ceramic industries.

Since pebble grinding bodies have a density of about one-third that of metallic media, these mills are of lighter construction and require only about one-third the horsepower of a ball mill of equal size. Capacity is approximately one-third that of a ball mill.

A Ballpeb mill is a secondary ball mill having either one or two compartments. This mill is specifically designed for operation in series with a Preliminator mill, or as a finish grinding mill with small size feed. Ballpeb mills will produce a finished product from relatively fine feed in open or closed circuit. The Ballpeb mill will take the product of a Preliminator mill and produce finished kiln feed, finished cement, mine dust, sized calcined coke, etc.These mills are equipped with thinner shell liners and employ smaller size grinding media than Preliminator mills.

Ball mills originally were used to grind approximately 2 in. material to pass 10 to 80 mesh screens. Present day practice is to use a feed of about 1/2 in. or finer. Product size has become increasingly finer and no actual grind limit is indicated.

The principal field for ball mill grinding has been the metalliferous ores and the more abrasive minerals. Because of the mills inherent characteristics of simple operation and low maintenance, it is gaining acceptance for grinding materials formerly ground in other types of mills.

Ball mills used in the mining industry are invariably short, the length being roughly equal to the diameter. When close circuited with a classifier, the short length of the mill and the high circulating load allows a short retention time with minimum overgrinding.

Preliminator mills are widely used in the cement industry for the reduction of cement raw materials and clinker. It is also used for the reduction of abrasives, refractories, limestone for mine dust, etc.

These mills can handle 1 in. feed. To grind this large feed efficiently, Preliminator mills are provided with thick shell liners and employ large balls as grinding media. Length is generally equal to or somewhat greater than the diameter.

The Compeb mill is a type of ball mill designed to incorporate the Preliminator and Ballpeb mills in one relatively long shell. The initial or primary grinding compartment is lined with thick liners and carries large balls to accomplish the coarse grind. This primary compartment is followed by one or more secondary compartments which are provided with thinner lining and smaller grinding bodies. In the secondary compartments the product of the primary compartment is further reduced. Thus, the Compeb mill offers complete grinding from coarse feed to finished product in a single mill, either closed or open circuit.

Ourgrinding mill shells are fabricated of rolled steel plate of a thickness sufficient to insure against distortion or failure in operation. Shells are of all-welded construction, welded one plate to a circle. Welding is done by an automatic welding process which assures full penetration and an even flow of weld rod for uniform strength. Comparable results are difficult to attain by hand welding methods.

Todays millhas unsurpassed facilities and personnel for the precision rolling of mill shells of consistently uniform diameter. Shells of true circular shape result in more uniform load on bearings, gears, drives, and permit better shell liner fit.

Grinding mill shells up to 26 feet in length are rolled from structural steel plate having approximately 55,000 psi tensile strength. Shells longer than 26 feet are rolled from carbon-silicon flange quality steel plate having approximately 60,000 psi tensile strength.

Flanges for mill shells are fabricated of rolled steel bars. Shells are welded integral to flanges, which are not machined until the entire welding operation on the shell, including the attachment of the manhole frames, has been completed. This machining operation (see illustration) assures that flange faces will be true with one another and that all parts will be in alignment.

When the nominal mill length exceeds twice the diameter, the entire mill is stress-relieved as a unit, prior to machining the flanges. Heat treatment relieves the residual stresses caused by rolling and welding . . . assures low bending stresses on long mills.Holes for shell liner bolts on all mills are drilled, not punched.

Allis-Chalmers grinding mill heads are cast of iron or steel and bolted to the shell flange with through bolts. These bolts are relieved of shear stress by a machined male and female joint between head and shell flange. All ball, rod and Preliminator mills, as well as the shorter Ballpeb and Compeb mills, have conical heads. The longer Ballpeb and Compeb mills have starfish heads (see illustration) which offer extra body and strength by means of a pattern of external braces.

Whether of conical or starfish design, all heads and trunnions are cast integral. This makes the task of maintaining alignment of the mill much simpler than on mills where head and trunnion are two separate pieces. Trunnions are machined true with head fit. Thus, when the head is attached to the shell flange, the trunnion is concentric with the true horizontal axis of the mill.

The sturdy construction of these trunnion bearings assures more than adequate support for the revolving mass of the grinding mill. Bearings are designed with sufficiently low bearing pressure to assure long bearing life and trouble-free operation.

The use of babbitted bearing and the ball and socket design are two important features of thesetrunnion bearings. Experience has shown that there is less possibility of scouring the trunnion with babbitt than with any other material. The ball and socket design corrects for minor misalignment during mill erection

Weoffers large mills with oil lubricated trunnion bearings and small mills with grease bearings. Grease lubricated bearings have a large space within the bearing cap for grease. Oil lubricated bearings are lubricated with a positive internal oiling system or, if desired, an external system.

The cross-sections on the opposite page show the mechanism of the oil and grease lubricated bearings. In the oil type, an arm extends radially from the trunnion. A cup fixed to the outer end of this arm fills with oil from the reservoir, when the mill rotates, and is brought up and discharged onto the distributing pan, providing flood lubrication to the trunnion.

Experience has proved this an effective means to lubricate the bearing. Sufficient oil in the reservoir assures proper lubrication. The piston ring seal is an effective way of sealing the bearing from dirt while retaining the oil. Economy conscious operators are aware of the lower coefficient of friction attainable with oil lubrication.

A most important adjunct of the oil lubricated bearing is the manually operated high pressure pump used to float the mill before starting. Large, heavy mills lock when idle for long periods. This occurs when the idle load of the mill squeezes the oil out from between the trunnion and trunnion bearing. Floating the mill provides an oil film between metal parts, reduces friction before starting, and eliminates the high bearing wear incident to dry starting. A floated mill also reduces the high inrush of starting current an important advantage often overlooked when considering the merits of various grinding mills. If grease lubricated bearings are used, a mill can be floated by using a manually operated grease pump. Although this is optional equipment, the resultant advantages under starting conditions are the same.

Allis-Chalmers mills are provided with steel sole plates under the trunnion bearings. All mills have adjustable sole plates for lateral movement of the mill. On direct connected mills the sole plate at the gear end is extended for bolting to the steel pinionshaft sole plate.

Todaysgrinding mills are equipped with a new, improved 20 true involute cut tooth spur gear with short addendum gear and long addendum pinion. This design assures overlap of tooth contact by as much as 40 percent. The pinion teeth roll evenly on gear teeth, resulting in smooth, even transmission of power from pinion to gear. Comparative results have proved the 20 involute gear a most suitable gear for smooth mill operation and long gear life.

Gears for 3, 4 and 5 ft diameter mills are made of high quality cast iron with cut teeth; gears for the larger mills are made of either cast or welded steel, with cut teeth. The teeth are cut to a true form and then subjected to a thorough inspection of spacing and profile. The resultant uniformity of teeth assures long service.

The millsmain drive pinions are fabricated of forged steel and the teeth are carefully cut to assure smooth mating action with the main gear. Pinions meshing with steel gears are hardened to prolong their life.

Main gears are reversible and split in halves to permit easy removal and reversal. All main gears on direct driven dry grinding mills are manufactured with an extended flange on both sides of the teeth to provide a seat for the oil and dust seal which is a part of the gear guard and lubrication housing.

Theserod and ball mills may be equipped with either herringbone or single helical gears. These are not recommended for Preliminator, Ballpeb or Compeb mills because the heat generated during dry grinding results in expansion problems.

Direct drive spur pinions are mounted on a short reversible stub pinionshaft which permits reversing the pinion without removing the pinion from the shaft. The pinionshaft is keyseated for both spur pinion and coupling. For mills equipped with Texrope drive, pinionshafts are keyseated for pinion and Texrope sheave.

In all mill sizes, the pinionshafts are mounted in antifriction (roller) bearings which are considered superior to the babbitted sleeve type for these reasons: (1) Roller type bearings offer a decreased coefficient of friction. (2) Since the wear on an anti-friction bearing is negligible, the alignment of gear and pinion is maintained. (3) Antifriction bearings require minimum lubrication and provide excellent seals for keeping dust and dirt out of the bearing.

Wet grinding mills of 6 ft diameter and larger are fitted with semi-enclosed safety type guard. Preliminator, Ballpeb, Compeb, and dry grinding ball and rod mills have gear and pinion totally enclosed in a 360 steel plate lubrication housing.

The lubrication housing protects the gear and pinion from outside dust and dirt, materially lengthening the life of the gears by preventing unnecessary wear from abrasive dust. The housing is supplied with a heavy, long-life felt seal which bears against the extended flange of the gear and thus effectively seals the gearing from dirt.

The gear housing for Preliminator, Ballpeb and Compeb mills is provided with a plastic impregnated laminated fabric oiling pinion which is located in an oil reservoir in the bottom of the housing. This lubricating pinion mates with the main gear and, when the mill is rotating, transfers oil to the gear teeth which in turn lubricate the drive pinion.

For grinding mills of 250 hp or less, the Texrope V-belt drive has proven to be most satisfactory. Actually, the Texrope drive may be supplied for mills larger than 250 hp but the arrangement is usually undesirable because of the outboard bearing required by the motor and the large size of the driven sheave.

The Texrope drive employs a driven sheave mounted between the outboard bearing and one of the bearings adjacent to the pinion. The driving sheave is mounted directly on the motor shaft. Such a drive is flexible and economical both in initial cost and in maintenance, repair and replacement. A wound rotor motor is recommended for use with a Texrope drive.

This type of drive is used to permit the use of high speed motors or to meet special space requirements. Speed reducer drives offer a highly efficient and economical means of stepping down motor speeds. The speed reducer may be located either alongside or at the end of the mill.

With either the direct connected or speed reducer drive, the gear is aligned with the pinion by means of a set screw adjustment on the main bearing sole plates. This adjustment can be made without disturbing the alignment of the motor and pinionshaft. Weoffer several possible drives in its direct connected series. A mill can be provided with a low speed synchronous motor having torques of approximately 40% starting, 30% pull-in and 175% pull-out for use with a magnetic clutch. A magnetic clutch drive may involve a close coupled unit with two pinionshaft bearings and combination clutch-coupling (Drive 1), or four bearings with a clutch and flexible coupling (Drive 2). The use of a magnetic clutch permits the use of a reduced voltage starter to reduce the starting kva which would result when a full voltage starter is employed.

The most compact direct drive, where electrical conditions permit its use, is the direct connection of a high torque synchronous motor (approximately 160% starting, 140% pull-in and 225% pull-out) to the pinionshaft through a flexible coupling (Drive 3). When plant design makes it essential to locate the motor at a distance from the mill, the drive arrangement may be as shown in Drive 4 or 5.

In addition to the drives described above, weoffer the synchronous-induction motor, which is wound so as to permit the use of a reduced voltage starter. This motor starts its operation as a wound rotor motor but reverts to a synchronous motor after it picks up speed and comes into step. This permits use of a synchronous motor with low starting current inrush and without magnetic clutch. This arrangement is used where a magnetic clutch is not desired and where electrical transmission line characteristics do not permit high starting kva.

Grinding mills for the mining, cement and rock products industries may he furnished with or with-out mill feeders, as desired. Feed chutes can he any one of several types which convey the material into the mill. None of the feeders described here weigh or proportion materials fed to the mill. Weighing or proportioning feeders can he purchased from several manufacturers and many operators feel that a feeder which controls and records the feed rate is well worth the additional cost.

This type handles dry, dusty feed and is no .longer in general use. Screw feeders can be designed to feed material into the mill and, at the same time, effectively seal the trunnion opening. This is essential for grinding some materials in a controlled atmosphere, other than air. Screw feeders have individual motor drives.

The spout feeder is the simplest of all feeders. It consists of a cylindrical spout or chute lined with either steel wearing plates or rubber lining. Spout feeders are used where the feed, plus the circulating load, if any, has sufficient elevation to be spouted directly through this feeder into the trunnion opening of the mill. Generally, the spout feeder can be used wherever a drum feeder is used. It has the advantage of permitting a constant flow of feed, resulting in higher capacity through the feeder. Most operators prefer the spout feeder because of its simple and inexpensive maintenance.

In closed circuit grinding, scoop feeders return classifier sands to the mill for regrinding. They may also be used to take initial feed and may be of either single or double scoop construction. The illustration above shows the double scoop type. The opening in the center is used to charge balls into the mill. Scoops are provided with replaceable wearing tips.

The drum feeder is the logical substitute for a spout feeder if the bin storage lacks sufficient headroom to spout the material successfully.This feeder consists of a steel plate drum or housing, a spiral made of high quality cast iron and suitable liner plates for the housing. If the material being ground is corrosive, the feeder may be constructed of stainless steel throughout.

The overflow mill, used for wet grinding, is the simplest of the three basic mill designs. Pulp in overflow mills is discharged by displacement, the new feed to the mill displacing an equal volume of ground pulp.

Since there is no appreciable pulp gradient within the mill, all the grinding media is surrounded by pulp to be ground. This cushioning by the pulp tends to reduce wear of grinding media and liners. The cost of metallic balls, rods and liners has risen steadily in the past decade and many operators have chosen the overflow mill to reduce their operating costs. Furthermore, the overflow mill does not have a diaphragm, component parts of which are more complex, expensive and short-lived than the comparable end liner in an overflow mill.

The capacity of the overflow mill is not as high as a diaphragm mill with the .same size grinding chamber. Power requirements per ton of material ground are substantially the same for either type mill.

Overflow mills have proven mot popular as secondary mills in a two-stage circuit, as employed in the mining industry. There are some operators who prefer the overflow mill for single stage closed circuit grinding of large feed.

The peripheral discharge, as used in a rod mill, is a means of establishing a gradient within the mill without the use of a low-level diaphragm. This cannot be done in a ball mill unless a special division head is used.

Occasionally, a multi-compartment mill is used with peripheral discharge openings following either the first or second compartments. A plain division head is used to retain the charge of balls or Concavex grinding media. Material is discharged and classified, the oversize returning to the (original) feed end of the mill and the fines being fed through the opposite end of the mill for further grinding.

The discharge end of this mill is fitted with a diaphragm, i.e. a perforated steel plate placed approximately 6 in. from the discharge head. Lifters between this perforated plate and the mill head elevate the ground material and drop it on a discharge cone (see illustration) which directs the material into the trunnion and out of the mill.

The function of the diaphragm is to retain the grinding media and allow free passage of the wet pulp or dry material through the perforations. On starting, the pumping action of the diaphragm lifters establishes a gradient within the mill. For grinding dry materials a steep gradient is essential to move the material through the mill. In wet grinding this gradient results in a short retention time per particle, with the advantage of less overgrinding.

Diaphragm mills have been designed with twovariations, Low-Level and Intermediate Level types. In the first, the diaphragm sections are perforated down to the periphery of the mill, which establishes the maximum gradient within the mill. The Intermediate Level diaphragm mill establishes a gradient which is less steep by maintaining a pool of pulp at the discharge end. Diaphragm perforations are held to within 10 to 18 in. (depending on the mill diameter) of the periphery. Size for size, the Intermediate Level mill offers a capacity greater than the Overflow mill and less than the Low-Level diaphragm mill.

Use of the diaphragm is almost universal with ball mills in the cement and rock products industries because of the many dry grinding operations in this field. It is optional on ball mills in the mining industry, but not recommended for rod mills. Diaphragms are standard equipment for Preliminator, Ballpeb and Compeb mills.

Division heads are used in Compeb mills to divide the mill into two or three compartments . . . and in long Ballpeb mills to divide it into two compartments.Plain division heads are made in both dry and wet types. The dry type have screen plates on the feed side and solid wearing plates on the discharge side. Material in the first compartment cannot flush through into the second compartment, but must be picked up by wings between the screen and the solid side and discharged into a center cone which funnels the partially ground material into the succeeding compartment.

Grinding in small plants, as in larger installations, has proven to be the most costly of all unit operations from both capital and operating standpoints. Therefore, grinding deserves the most scrutiny of all operations during the design procedure.

A recent survey by a major grinding mill manufacturer reveals that more than 80 autogenous or semi-autogenous mills having between 100 and 1,000 connected horsepower have been sold during the last twenty years. Obviously, this type of grinding approach cannot be arbitrarily excluded from consideration in a small installation.

This configuration has proven in the past to be a most reliable system due to the fact that rod mills are not particularly susceptible to variations in feed size. However, the necessity to procure grinding rods may limit the usefulness of this approach in certain locations.

This configuration is employed when it is desired to produce a final ground product having a very high pulp density. This situation can be useful for various types of leaching circuits but does not normally apply to flotation concentrators.

Single stage ball milling has proven to be very popular in recent years. Both overflow and diaphragm (grate) ball mills have been used as single stage grinding units. If the feed to such a system can be top size limited, for example by the use of closed circuit crushing, this type of installation can prove to be the most efficient from both the capital and operating standpoint.

Occasionally, the liberation requirement for an ore requires very fine primary grinding. Usually, the most expeditious way to accomplish this objective is by double stage ball milling. Both mills are usually operated in closed circuit with separate classifiers.

In smaller plants, grinding mill drives should be as simple as possible. The drive train usually recommended consists of a slow speed motor which drives the mill pinion through an air clutch. This slow speed motor system tends to be slightly more expensive than the alternate drive train consisting of a high speed motor and speed reducer but the ease of maintenance and the simplicity of the slow speed system offset the additional cost.

The mill feed belt should be equipped with a weightometer having cumulative and instantaneous tonnage indicators visible both locally and in the control room. In recent years, load cell weightometers have proven to be very reliable and are relatively simple to calibrate. The digital readouts supplied with load cell weightometers have proven to be rugged and reliable.

The mill dilution water stream should be visible and its control valve should be readily accessable. A simple water proportioning valve is sometimes recommended to give semiautomatic regulation to mill dilution water.

Mill sizing for most grinding installations is usually arrived at through calculations involving required throughput, ore work index estimates, and feed and product size-distribution requirements. This information is then tempered with experience to arrive at actual mill size recommendations. In the case of small concentrators located in remote areas, the method and route of delivery to the plant site must also be considered. There are cases on record where mill diameter has been dictated by railroad tunnel dimensions and mill length by the presence of severe switchbacks and small bridges over precipitous canyons.

Ball mills should be equipped with trommels constructed of punched plate or screen cloth and are usually fabricated with a reverse internal spiral. The trash rejected by the trommel is normally collected in a forklift box.

Ball charging should be arranged for the convenience of the operator. In remote areas, grinding balls are usually received in welded 55 gallon drums each of which weighs between 500 and 600 kilograms. Suitable handling equipment for grinding media must be supplied by the design engineer. It should be noted that the ability to assemble a graded ball charge at the mill site prior to startup may not be possible. An initial properly-graded ball charge should be purchased from capital funds and included in the grinding area unit cost.

Rubber liners represent a significant cost saving for smaller installations. This type of liner, although possibly contributing to somewhat less efficient power utilization, is very simple to install with unskilled personnel as contrasted to conventional cast metal liners.

The necessity for regrinding is usually determined by laboratory or pilot-scale test work. If a project is to be designed from bench scale work only it is prudent to include a regrind mill in the circuit even though laboratory work does not indicate the necessity for this unit operation. Regrind mills are difficult to size since work index data are not generally available. Therefore, the design engineer should be generous when sizing a regrinding installation.

There is a tendency to employ spent grinding media from the primary grinding installation as media for the regrind mill. It is much better to use small-diameter properly-sized grinding media for regrinding since the utilization of spent media tends to reduce efficiency.

Regrind mills tend to be rather difficult to reline since they are usually of small diameter. Rubber regrind mill liners are an obvious solution and have found application in many installations. Of course, the rubber composition employed must be compatible with the flotation reagents associated with the regrind mill feed.

grinding cylpebs

Our automatic production line for the grinding cylpebs is the unique. With stable quality, high production efficiency, high hardness, wear-resistant, the volumetric hardness of the grinding cylpebs is between 60-63HRC,the breakage is less than 0.5%. The organization of the grinding cylpebs is compact, the hardness is constant from the inner to the surface. Now has extensively used in the cement industry, the wear rate is about 30g-60g per Ton cement.

Grinding Cylpebs are made from low-alloy chilled cast iron. The molten metal leaves the furnace at approximately 1500 C and is transferred to a continuous casting machine where the selected size Cylpebs are created; by changing the moulds the full range of cylindrical media can be manufactured via one simple process. The Cylpebs are demoulded while still red hot and placed in a cooling section for several hours to relieve internal stress. Solidification takes place in seconds and is formed from the external surface inward to the centre of the media. It has been claimed that this manufacturing process contributes to the cost effectiveness of the media, by being more efficient and requiring less energy than the conventional forging method.

Because of their cylindrical geometry, Cylpebs have greater surface area and higher bulk density compared with balls of similar mass and size. Cylpebs of equal diameter and length have 14.5% greater surface area than balls of the same mass, and 9% higher bulk density than steel balls, or 12% higher than cast balls. As a result, for a given charge volume, about 25% more grinding media surface area is available for size reduction when charged with Cylpebs, but the mill would also draw more power.

buy ore ball mill for mineral processing | iron & gold ore ball mill

Ore ball mill sometimes called ore grinding mill, is generally used in mineral processing concentrator, processing materials include iron ore, copper ore, gold ore, molybdenum ore and all kinds of nonferrous metal ore. The core function of the ore ball mill is to grind the materials, and also to separate and screen different mineral materials, and to separate the tailings, which is very important to improve the quality of the selected mineral materials.

The ore ball mill designed by our company, which is represented by gold ore ball mill and iron ore ball mill, is manufactured with high-quality materials and advanced technology. They have the characteristics of high efficiency, energy-saving, green environmental protection, simple operation, stable operation, and low failure rate, and have a good reputation in the industry.

The crushing ratio of the ore grinding mill is very large, and it is easy to adjust the fineness of the grinding product. The ore grinding mill has strong sealing performance and can be operated under negative pressure. It is widely used in chemical industry, metallurgy, new building materials and other fields.

We offer different types of ore ball mills for customers to choose from. There are energy-saving ore ball mill, dry and wet ball mill,wet grate ball mill, andwet overflow ball mill. Customers can choose to purchase according to material conditions.

Mineral processing is the most important link in the entire production process of mineral products. It is a process of separating useful minerals from useless minerals (usually called gangue) or harmful minerals in a mineral raw material by physical or chemical methods, or a process of separating multiple useful minerals The process is called mineral processing, also known as ore processing.

The first step in the ore processing is to select the useful minerals. In order to select useful minerals from ore, the ore must be crushed first. Sometimes, in order to meet the requirements of subsequent operations on the particle size of materials, it is necessary to add a certain ore grinding operation in the process.

The preparation before beneficiation is usually carried out in two stages: crushing screening operation and mineral classification operation. Crusher and ore ball mill are the main equipment in these two stages.

As a ball mills supplier with 22 years of experience in the grinding industry, we can provide customers with types of ball mill, vertical mill, rod mill and AG/SAG mill for grinding in a variety of industries and materials.

trommel screen - pineer mining machinery

Trommel screen also known as rotary screen, is a kind of mechanical screen machine for separating mineral ore material, mainly used in the gold wash plant and solid waste treatment industry. The trommel controls the mineral separation by the size of the particles, and the separation precision is high.

The cylinder of the drum screen is generally divided into several sections, depending on the specific circumstances, the screen holes from small to large arrangements, each section on the same size of the screen hole. The trommel screen mainly comprises a motor, a reducer, a roller device, a machine frame, a sealing cover and an inlet and outlet.

When feeding ore material into the drum, the material begins to rotate and tumble inside the drum before calming down intermittently. This revolution is completed along the length of the drum. Hence, the finer materials pass through the screen openings while the larger ones tumble to their exit through the rear end of the drum. Separation of different materials is done efficiently.

jig machine - pineer mining machinery

Jig Concentrator is one of the ideal devices in energy-saving gravity separation, mainly used in the mining industry for ore dressing, such as tungsten, tin, gold,etc. Our jig machine adopts advanced jig technology, reach the leading level.

The jig separator is a deep-groove type of equipment in the mining industry. The jigging indoor sieve plate is made of punched steel plate, braided iron mesh or purling. The flow of water through the sieve plate into the jigging chamber should raise the bed to a small height and be slightly loose. The dense particles are partially localized. The pressure and sedimentation velocity are large and enter the bottom layer, and the particles with low density are transferred to the upper layer. When the water flow drops, the fine particles with high density can also enter the lower layer through the gradually tight bed gap. The mechanism for supplementing the layered agitating water flow according to the density adopts the piston in the early years. The piston chamber is located beside the jigging chamber, and the lower part is connected. The eccentric link mechanism drives the piston up and down.