hydrocyclone for classifiers in ore dressing concentrators separating fines desliming and sand removing

hydraulic classifiers

Hydraulic classifiers range from simple V-shaped launders with a multiplicity of shallow settling pockets for the discharge of as many roughly sized products to the more elaborate deep-pocket machines of the hindered- settling type, having specially designed construction plates and automatic discharge of spigot products.

In the eight-pocket machine, the pockets are separated by 3-ft.-high partitions and increase in cross-sectional area from 1 sq. ft. in the feed end to 3.12 sq. ft. in pocket 8. The size of hole and hole spacing in the constriction plates depend upon the size distribution of the feed and are designed individually for each installation, so that the hydraulic water required for each compartment will flow through the holes at a predetermined head loss. This hydraulic water is supplied from take-offs arranged along a common manifold, and the flow is controlled by individual valves. Windows are provided in each compartment for inspection of the teeter bed. The discharge mechanism is fully automatic, the spigot valves being operated by a modulating motor controlled by a pressure unit that, in turn, is actuated by the pulp density within the compartment. This eight-pocket unit operating on minus 14-mesh iron ore of average size distribution has a feed capacity, when overflowing minus 100-mesh material, of about 25 tons of solids per hour.

Hindered settling machines require no power except for the water used and are automatic in discharge, although they need a certain amount of attention. On many materials they give excellent results either in closeness of sizing or in concentration of the denser particles. They are used, therefore, chiefly for two purposeseither in separating 6- to 200- mesh material into a series of closely graded portions for subsequent treatment or in concentrating the heavier mineral of a non-homogeneous feed.

In general, however, hydraulic classifiers use more water than mechanical classifiers, the slime overflow is more dilute, the coarse fractions contain a much higher moisture content, and the loss of head on the sands is considerable, which is objectionable in closed-circuit grinding. Also, these classifiers frequently require a deslimed feed.

Thus in practice, for preparing cyanide or flotation pulps, mechanical, non-hydraulic classifiers are used almost to the exclusion of all other types because of their capacity, flexibility, continuous operation, and uniformity of results. In addition, they require little attention and give a coarseportion or sand of low moisture content. Furthermore, the mechanical- type classifiers give a coarse portion that is sufficiently free of fines for practical closed-circuit grinding. This is the result of the agitation and draining that take place during the removal of the coarse portion.

A hydro-separator is, in working principle, an undersize thickener, i.e., a machine of such a specified diameter that the upward displacement rate is greater than the settling velocity of the largest particle it is desired to separate. In consequence, particles of this critical size and finer are carried into the overflow, and the settled material, which is carried to a central discharge opening by a slowly moving raking mechanism, is relatively dislimed.

As in the case of mechanical, in contrast to hydraulic, classifiers generally, a considerable amount of the finer fraction is entrained with the underflow sands. Used both as deslimers for making final separations after grinding and also for closed-circuit grinding work, they have the advantage of providing the relatively large areas required for fine separations at high dilutions.

A = 1.333(F + 1/sp. gr.)/R where A = square feet per ton of overflow per 24 hr. F = overflow dilution R = settling rate in feet per hour at over-flow dilution F sp. gr. = specific gravity of the solids

The metallurgical advantage of fine grinding in the treatment of many ores by the all-sliming cyaniding process has of course been realised ever since the introduction of the process. An economical means, however, of attaining a finely ground product has been a gradual development to which improvements in grinding mills and classifiers have contributed the greatest advance.

The mill-classifier combination should be considered as a unit. The change from open circuit to closed circuit, the use of optimum circulating loads, and the development of secondary and tertiary grinding circuits are notable advances in producing an improved product, generally resulting in a higher extraction of the valuable constituents of the ore. This has been accompanied by a reduction in unit costs through a lowered consumption of power and steel and by increase in capacity of the grinding mill.

Classification as applied to cyanide plants is usually a combination mechanical-hydraulic operation which separates the solid constituents of a flowing pulp into two portions according to their respective settling rates. Usually it implies the removal of a finished product, termed overflow, from a product requiring further grinding, termed sand. Pulp means a uniform suspension of finely divided solids in liquids as applied to mechanical classification, which is the usual method of making a sand-slime separation in cyanide plants. Overflow is the comparatively finer, more slowly setting portion of the original pulp which is carried over the tailboard or lip of the classifier by the flow of water; sand is the comparatively coarser, more-rapidly settling portion of the original pulp which is discharged from the classifier by the mechanical action of the rakes. Selective classification is classification that has for its object the concentration of the heavy constituent of the original pulp, generally the sulphide, in the sand product, so that it may be ground finer than the lighter portion, generally the gangue.

A grinding mill may operate open circuit or closed circuit. Open-circuit grinding is a method of comminution that produces the desired reduction in particle size by a single passage of the material through a mill. Closed- circuit grinding is a method of comminution in which a partly finished mill discharge is separated by the classifier into a finished overflow productand an unfinished sand product which is returned to the mill for further grinding.

The desired function, together with the character of the ore and such factors as the tonnage to be handled, mesh of separation, etc., determines the selection of the proper size and type of classifier. The single-stage classifier such as the Dorr (see Fig. 19 and 20), Akins, and Wemco, and bowl-type classifiers such as the Dorr (see Fig. 21) are in use for making separations from as coarse as 20 to as fine as 350 mesh. The first of these are better suited for making coarse separations and for handling large circulating loads where relatively small overflow capacity is required. The bowl classifier, limited to 48 mesh and finer, with the double washing action gives a closer separation at the desired mesh and a cleaner sand product;permits, through the selection of the proper bowl size, any required relation between overflow and sand-raking capacity; and is more suitable as a mineralconcentrator for selective classification.

Both machines are capable of adjustment to cover considerable range of conditions. Adjustments in slope of classifier tank, rake speed, and dilution of overflow pulp and, in the case of the bowl classifier, additional adjustments of backwash water and bowl speed are available to obtain efficientresults at any mesh of separation. In designing the machine, due consideration is given the results desired under specified conditions; final adjustments are made when the particular flow sheet is placed in operation and are varied thereafter as the conditions vary.

The first application of the mechanical classifier was to open-circuit work with grinding mills in the cyanidation of gold and silver ores, for the purpose of producing two productsa slime-free sand for treatment by percolation and a sand-free slime for treatment by agitation and filtration or decantation.

Advances in the art of treating cyanide slimes and the reduced cost of fine grinding made possible by the early tube mills led to the use of the mechanical classifier as a means of controlling the fineness of the pulp leaving the grinding plant as feed to the all-slime cyanide treatment. Operating in closed circuit with the tube mills, the classifier not only controlled fineness more accurately but greatly reduced grinding costs.

The adoption of two-stage fine grinding, due to a recognition that too great a size reduction in one mill with one ball charge was uneconomical, led to the use of the primary mill and subsequently a mechanical classifier in closed circuit with it. Reductions in grinding costs were again obtained, and in addition a convenient means was provided for apportioning the work between the two stages.

Another step was the interposition of a bowl classifier between the primary and secondary grinding circuits. The classifier operated in open circuit receiving as its feed the overflow from the primary circuit, overflowing material of finished size, and discharging a clean sand product direct to the closed-circuited secondary mill. This step, however, is not generally desirable largely because of the difficulties met in controlling the succeeding classification stage in the absence of primary slime.

Finishing the entire mill feed in a bowl classifier, with provision for regrinding the sands in a separate or tertiary circuit, first proved attractive in the cyanidation of gold ores in which the values were chiefly associated with the heavy pyrite constituent. Here the bowl reclassified selectively the relatively coarse pulp from the secondary circuit, overflowing the bulk of the quartz and only the finest sulphides for treatment, concentrating the sand product to five or six times the assay of the original ore, and regrinding this high-grade material as fine as its assay warranted.

The net result has been a higher extraction, a coarser over-all grind, and a reduced grinding cost. The same principle has been applied successfully more recently in the dressing of copper sulphide ores for flotation. The sulphide mineral, being heavier than the gangue, concentrates readily in the bowl sand and is subjected to regrinding for more complete liberation of associated minerals. In this way the mill is not burdened with gangue materialupon which no further work is required. Moreover, the finishing-bowlclassifier protects the flotation operation against tramp oversize frompreceding classifiers and assures a uniform product from the entire fine-grinding section, convenient for sampling and distribution to the succeeding units.

In general, open-tank rake-type, screw-type, or bowl classifiers are used for closed-circuit grinding work where a finished product is desired. In some cases, however, especially for very fine separations requiring high overflow dilution, hydroseparators are used to good advantage, and because ofthe difficulty of raking extremely fine sand up an inclined deck, bowl-type classifiers have been converted to shallow hydroseparators with spigot discharges. The open-tank rake-type or screw-type machines are also more generally suited to coarser sizes of feed, while the bowl classifier, hydros, and centrifuges are applied more generally to handling finer (minus 20 mesh) feeds and to making finer separations. Where exceptionally large volumes must be handled, however, the hydroseparator has been installed to handle feeds as coarse as 4 mesh, using a spigot discharge. Hydraulic classifiers operate in the size range of about 8 to 200 mesh but find their principal use in preparing a number of closely sized products and in the concentration of heavy minerals.

Screw classifiers such as the Akins and Wemco consist of a semi-cylindrical trough, usually set at a slope of from 2 to 3- in. per ft., in which rotates a helix or spiral at from 2 to 8 r.p.m. depending upon size and conditions to be met.

The feed is introduced through the side of the tank just below the pulp level. The heavier solids settle out and are carried upward out of the pulp by the spirals and discharged into a sand launder, while the fines flow in the opposite direction to the overflow weir at the lower end of the tank.

The earlier types of machine used interrupted spirals and overflow lips below the shaft carrying the spirals at the lower end. The design has now been modified. In the high-weir type recommended for coarser separations the spirals extend above the pulp level, and in the submerged type recommended for fine separations the spirals are below the pulp level inthe lower end of the tank. Either type may be supplied with single or double spirals, and both are equipped with lifting devices. Figure 22 shows an Akins submerged-type machine. In the triple-pitch Wemco design (Fig. 23) three spirals per shaft provide additional sand-conveying capacity per revolution.

The Dorr Company is the principle advocate of this machine.Single-stage Type. The Dorr classifier (Figs. 19 and 20) consists of a rectangular, inclined settling box of wood, steel, or concrete, with the upper or discharge end open, in which are placed mechanically operated rakes or scrapers which carry the quick-settling, coarse particles to the point of discharge at the open end. Each rake, of which there may be as many as six, is carried by two hangers, one at the discharge end and one near the overflow end. The rakes are raised, lowered, and moved parallel to the sloping tank bottom by a suitable head motion. A lifting device is provided for raising the rakes several inches to clear the settling solids in case of a shutdown.

The feed enters continuously, through a distributing launder near the overflow end. The more quickly settling particles fall to the bottom and are advanced up the inclined deck by the rakes and discharged. The agitation of the reciprocating rakes keeps fine particles in suspension until they overflow the weir at the lower end.

The point at which a separation can be made is determined by the rake speed, the pool area, and the overflow dilution. The greater the rakespeed the greater the overflow density, and the smaller the pool area the coarser the separation.

Bowl Type. The Dorr bowl classifier (Fig. 21) is a combination of a shallow, circular bowl with a revolving raking mechanism superimposed on the lower or overflow end of a single-stage Dorr classifier. Feed enters through a loading well at the center of the bowl, and fine solids overflow across a peripheral weir. Coarse solids settle on the bowl bottom, are raked to a central opening, and gravitate through it into the reciprocating- rake compartment.

The Hardinge Company was responsible for introducing the spiral ribbon type of mechanical classifier as illustrated in Fig. 24. This classifier is a slowly rotating drum, on the inner surface of which is a screw flight attached to the drum, revolving with it. The material to be classified is fed in at one end above the pulp level, and as theclassifier rotates, the coarse particles that settle out are moved forward by the screw flight. The fines overflow through an opening at the feed end of the classifier. The sand or oversize is dewatered and elevated by buckets to the discharge hopper.

A number of mill flow sheets include the step of removing the softer fraction of the ore (clay and related material) from the harder fraction preceding or as a part of the crushing and grinding sections.

At Marlu Gold Mining Areas in West Africa (Fig. 89) the ore after passing through a jaw crusher is washed at 1-in. size in a series of twelve 4 by 16-ft. trommel washers, the undersize being sent to bowl classifiers fordesliming and the washed rock being crushed in Newhouse crushers and passed to the ball-mill circuit (which also receives the sands from the desliming classifiers).

At the Dome mines in Canada (Fig. 64) the jaw-crusher product is first washed on vibrating screens, the oversize passing to a-Symons cone crusher, while the undersize is. classified for removal of fine sand and slimes and the rake sands transferred to the mill bins.

In both of the above installations the objective is, of course, to eliminate primary slime which in the case of wet ores causes trouble in the crushers, but the combined pulp is cyanided in a single circuit.

In the case, however, of the treatment scheme devised to handle a difficult ore in the plant of the Kelowna Exploration Co. at Hedley, British Columbia (Fig. 71), the primary slime and softer fractions of the ore are treated in a separate circuit from that used to handle the harder ore constituents. This scheme has resulted in the successful treatment of an ore that otherwise failed to respond to ordinary thickening and filtering practice.

This machine is essentially a closed spiral classifier in which the tank is revolved at relatively high speed on a horizontal axis. The tank itself consists of a truncated conical shell, within which is a smaller concentric cone carrying a spiral ribbon (rakes) that revolves independently of the shell but in the same direction at a somewhat slower speed. Classification takes place in the annular space between the cone and the shell, the speed differential between the two elements having the effect of raking the solids settled against the shell up-slope to the small end, where they are discharged. The slime discharges through ports at the larger end. The machines are built in various sizes ranging from a raking capacity of 2 to 50 tons per hour, the latter requiring a 100-hp. drive motor.

At the Hedley Mascot mill in British Columbia, a change in the ore mined led to a serious slime problem which could not be handled in the conventional flotation and cyanide equipment installed at the mine. Following test work, a 36- by 50-in. Bird centrifuge was installed in January, 1941, to deslime the ore prior to flotation and has been in continous operation since.

According to C. W. S. Tremaine in Applications of the Bird Centrifuge at Hedley Mascot Mill, C.I.M. andM., Vol. 50, pp. 533-536, 1947, the centrifuge is operating on a mixture of slime from primary and secondary classifiers and concentrate taken from the scavenger flotation cells.

This mixture of slime and low-grade concentrate forms the feed to the Bird centrifuge; it amounts to about 2.5 tons per hour at 15 per cent solids, 98 per cent minus 325 mesh, and assays about 0.11 oz. per ton. The centrifuge discharges an effluent which carries 3 to 6 per cent solids and assays 0.06 oz. gold per ton. The cake is discharged at about 82 per cent solids, 92 per cent minus 325 mesh, and is sent to the cyanide plant, where it is treated in conventional manner. The centrifuge machine is driven by a 30-hp. motor and operates at 1000 r.p.m.

The hydraulic cyclone, which was developed by the Dutch States mines in connection with their coal-cleaning processes, is the most recent classifying-thickening device to be used commercially for the separation of fine particle sizes.

The design and principle of operation of the hydrocyclone are similar to that of the familiar dry cyclone or dust collector. It is a closed vessel consisting of a conical section surmounted by a cylindrical section of equal diameter. The feed is pumped into the cylindrical section at a pressure of 5 to 50 lb. per sq. in. through a tangential opening, the fines overflowing through a central orifice on top and the coarser fraction discharging through a second orifice at the apex of the cone.

The high rotational velocities developed inside the vessel set up centrifugal forces equal to many times the force of gravity, and high rates of separation are obtained. The coarser material is thrown to the sides of the cone and forced by a pressure differential toward the discharge orifice, emerging as a thickened sludge, while the fines are displaced through the overflow opening.

The capacity of the hydrocyclone and the separations made depend upon a number of design factors, including the shape and size of the vessel, the pressures used, and the size of overflow and discharge orifices.

Though still in the experimental stage, performance data to date indicate that this device will find considerable use in the field of classification and desliming. It possesses the advantage of high capacity for size and relative simplicity of construction, which involves no moving parts. The only power required is that used for pumping the feed into the vessel.

hydrocyclone | particle size separation - jxsc machine

Description Hydrocyclone is used for separating and removing heavy mud and sand of coarse particles and sometimes for dehydration of slurry. The Hydrocyclone separator has two types of pressure type and gravity type made up of either cylindrical structure or metal pipe. Water is fed through the top of the structure (or metal pipe) by means of pressure or gravity along the tangent line. Coarse and thick particulate matters are thrown to the wall, rotated down and discharged together with the concentrated liquid formed under the action of centrifugal force. Small particulate matters are discharged together with secondary upward vortex after rotated to some extent.

Hydrocyclone/ cyclone filter is mainly used for classification, separation, concentration and desliming in the mineral mining industry. When the hydrocyclone is used as a classifier, it is mainly used to form a grinding and classification system with a mill; when it is used as a deslimer, it can be used for desliming in a gravity concentrator; when it is used as a concentrating and dewatering device, it can be used to concentrate ore dressing tailings and send them to fill underground mining tunnels. The hydrocyclone sand separator has no moving parts, simple structure, large capacity per unit volume, small area, high classification efficiency (up to 80% ~ 90%), fine classification granularity, low cost, and low material consumption. JXSC, your reliable partner of hydrocyclone manufacturer, hydro cyclone design service is available. If you need other ore particle size grading and screening machines, click here!

Hydrocyclone Working PrincipleThe Hydrocyclone consists of a hollow cylinder at the top and an inverted cone at the bottom, which is connected to the cylinder to form the hydrocyclone. In addition, the hydroclone also has feed pipes, overflow pipes, overflow conduits and sinks. The hydro cyclone pump (or height difference) rotates the slurry into the cylinder along the Tangent Direction with a certain pressure (generally 0.5 ~ 2.5 kg/cm) and flow rate (about 5 ~ 12 m / s) , and then the slurry rotates along the cylinder wall at a very fast speed to create centrifugal force. Under the action of Centrifugal Force and gravity, the coarse and heavy ore particles are thrown out. The suspension enters the hydraulic cyclone at relatively high speed from the feed tube in a tangential direction and rotates from top to bottom. This motion is commonly referred to as external or descending swirl motion. The solid particles in the external swirl flow are separated from the suspension by Centrifugal Force and move down the wall of the device to discharge from the bottom outlet.

stainless steel hydrocyclone, stainless steel hydrocyclone suppliers and manufacturers at

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There are a lot off suppliers providing stainless steel hydrocyclone on okchem.com, mainly located in Asia. The stainless steel hydrocyclone products are most popular in India, Pakistan, Vietnam, Indonesia, Brazil, Russia, Mexico, United States, Turkey, Germany, etc.

hydrocyclone separator - xinhai

The hydrocyclone separator is an effective mineral processing equipment for ore classification. The pulp is sent into the hydrocyclone separator along the tangent direction at a certain speed to rotate. Under the action of centrifugal force, the coarser particles are thrown to the wall of the hydrocyclone separator, moving downward in a spiral trajectory, and are discharged into coarser products from the settling nozzle. The fine particles and most of the water is discharged from the overflow pipe in an internal spiral trajectory, thus achieving the purposes of separation and classification.

In the production, the factors affecting the working efficiency of the hydrocyclone separator mainly include ore properties, equipment structure, and technological operation. Next, we will explain to you how these various factors affect the working efficiency of the hydrocyclone separator.

The higher the ore density, the finer the grading granularity. When the pulp concentration is large and the mud content is high, its viscosity and density increase correspondingly, which increases the movement resistance of the particles, and makes the grading granularity coarser. Therefore, it is necessary to complete the pre-desliming when the mud content is high. The suitable pulp concentration is usually determined by the mineral processing test according to the specific situation.

In terms of equipment structure, the factors that affect the working efficiency of hydrocyclone separator mainly include diameter and height of the cylinder, size of the feeding port, the diameter of the settling nozzle, diameter and depth of the overflow pipe, and the size of the cone angle.

The diameter and height of the cylinder have a certain relationship with the size of other parts, and it determines the separation size and production capacity of the hydrocyclone separator. When the ratio among the feed pressure, feeding port, overflow port and the diameter of the hydrocyclone separator remains constant, the production capacity of the hydrocyclone increases with the increasing diameter of the hydrocyclone separator, and the separation size also becomes coarser with the increasing diameter of the hydrocyclone separator.

The height of the cylinder mainly affects the time length of centrifugal force that the pulp is affected, thus influencing the working efficiency of the hydrocyclone separator. In general, the height of the cylinder should be 0.6-1.0 times of its diameter. The higher the cylinder height is, the finer the separation size is. However, if it exceeds a certain limit, it will lose its function due to the increasing of the ore feeding pressure.

The size of the feeding port will affect the working efficiency and production capacity of the hydrocyclone separator. Too large or too small feeding port is not conducive to the classification effect of the hydrocyclone separator. If the ore feeding size is coarser and the ore feeding pressure is lower, the ratio between the ore feeding port and the diameter of the hydrocyclone can be slightly larger (generally 0.16-0.20). However, when the ore feeding size is fine and the ore feeding pressure is high, the ratio between the ore feeding port and the diameter of the hydrocyclone is usually maintained at 0.14-0.16.

Usually, the diameter of the settling nozzle is large, the overflow flow is small, the overflow size becomes fine, while the settling amount increases, the concentration becomes low and the fine particles increase, but there is no obvious effect on the processing capacity of the hydrocyclone separator.

The diameter of the settling nozzle is small, the concentration of the settling is high, the discharge of the settling is reduced, and there is some coarse size in the overflow. Too small diameter will make the coarse grains accumulate more and more in the top of the cone, causing the blockage phenomenon.

The appropriate diameter of the settling nozzle should make the settling discharge in an umbrella shape, the included angle should be 40-70. The diameter ratio of the settling nozzle and the overflow pipe is generally 0.4-0.8.

The diameter of the overflow pipe should be proportional to the diameter of the hydrocyclone separator. The diameter of the overflow pipe increases, the overflow flow increases correspondingly, the overflow particle size becomes coarser, and the fine particle size in the settling sand decreases, the settling sand concentration increases, and the classification efficiency of the hydrocyclone decreases. In addition, the ratio between the depth of the overflow pipe and the height of the hydrocyclone cylinder should be maintained at 0.7-0.8. Too deep or too shallow depth will make the overflow grain size become coarser, and increase the content of fine grains in the settling sand, thus affecting the working efficiency of the hydrocyclone separator.

The size of cone angle has an important effect on the working efficiency of hydrocyclone. Small cone angle, long cone (large distance between overflow port and settling port) can increase the classifying volume, and strengthen the classification process of ore particles in the hydrocyclone separator, which is conducive to the separation of fine materials. The cone angle is generally 10-15 for the desliming of fine grains, and 20-45 for the classifying of the coarse grain grading.

In the production, the technological operation affecting the working efficiency of the hydrocyclone mainly includes ore feeding, overflow and discharge of settling sand, which requires the hydrocyclone operators to improve their skills in the production process, keep the technological parameters within a reasonable range, thus ensuring the stable operation of hydrocyclone separator.

The ore feeding pressure mainly affects the processing capacity of hydrocyclone and classifying size. With the increase of ore feed pressure, the slurry velocity is accelerated, the viscosity effect is reduced, and the classification effect of hydrocyclone is improved. Most concentrators adopt the low pressure (49-98KPa) for the treatment of coarse-grained materials, and the high pressure (98-294KPa) for the treatment of fine and muddy materials.

The feed concentration and size composition will directly affect the concentration and particle size of the final product. The coarser the classifying size is, the more mud or fine particle size in the classifying material is, the higher the feed concentration should be, the higher the slurry viscosity is and the coarser the particle size of the overflow product is.

The ideal working state of the hydrocyclone is that the settling sand is ejected in umbrella shape. Therefore, the angle of the umbrella should not be too large, so that it is appropriate to just spread out. When used for the concentration operation, the settling sand is discharged in a rope shape with a higher concentration. When used for dehydration operation, the settling sand is discharged in a larger umbrella shape with the least solid content in the overflow.

These are the three factors that affect the working efficiency of the hydrocyclone separator. It is worth noting that maintaining the working efficiency of the hydrocyclone is a systematic project, and all factors are interrelated with each other. Each concentrator must take all things into consideration for obtaining the ideal working efficiency of the hydrocyclone separator.

kaolin beneficiation technology and process flow,kaolin mineral processing,mineral separation-beijing hot mining tech co.,ltd

For the separation of kaolin in the quartz, feldspar, mica, iron minerals, titanium minerals such as clay minerals and organic matter, produce kaolin products to meet the needs of various industrial sectors, in addition to the re-election, flotation, magnetic separation of kaolin purified impurity, and sometimes chemical bleaching, ultra-fine flakes, calcined, surface modification and other deep-processing method for processing of kaolin.

Hydraulic classification spiral classifier (separation +1 mm coarse sand), sedimentation tanks classification (separation the +0.053 mm of fine sand), of hydrocyclone classification (separation-0.053mm fine sand), the centrifugal classifier or small diameter hydraulic cyclone classification (for ultra-fine-grained grading 0.002 ~ 0.010mm).

By adding flocculants, the selective separation of fine-grained quartz, pyrite, alunite and other impurities, producing blade coating grade kaolin. Top flocculant, sodium hexametaphosphate, polyacrylic acid such as ammonium, sodium silicate.

In a stripping machine by stirring fine media ball grinding stripping role, kaolin aggregate particles are separated into a sheet crystals, production size of less than 2m content of more than 90% of the blade coating grade kaolin.

In 800 to 1 000 C calcined kaolin water loss, phase transformation, while some impurities to volatile, improve kaolin whiteness and insulation, production of cable and rubber plastic filler. Calcined kaolin required processing method of coal measure (hard).

Dry mined ore passes through the crusher crushing to 25mm, giving into the cage crusher, the particle size is reduced to about 6mm. The moisture of kaolin to about 10% from about 20% of the recovery time of the hot air blown into the cage crusher. The broken ore then by further pulverized with a centrifugal separator and cyclone blowing Raymond. This process can remove most of gravel applicable to the processing of those raw ore whiteness, low content of sand, the particle size distribution suitable ore. The dry processing low production costs, usually cheap fillers for rubber, plastic, paper and other industrial products.

types of weak magnetic separators - jxsc machine

The industrial magnetic separation machine can be divided into the weak magnetic separator and strong magnetic separator (high-intensity magnetic separator). This article mainly introduces the types of weak magnetic separators, includes dry type, wet type, and auxiliary equipment.

You may interest in How many types of magnetic separators? What magnetic separators machine JXSC supply? wet type, dry type, high intensity, three-disc, etc. Contact us for magnetic separation machine selection help, price, processing plant design.

The iron remover is used to remove the iron lump and iron slag from the raw material, have an electromagnetic type and permanent magnet type. Iron remover installation: fixed suspension and belt suspension. A fixed suspended iron remover is suspended above the conveyor belt to pick up iron from the material flow. The width of the magnet corresponds to the width of the belt conveyor. It needs manually remove the iron from the magnet, so it only used in the small processing plants.

The belt suspension iron remover has two installation methods, as shown in the figure below. One is that the iron remover and the conveyor belt cross at right angles, and the iron is discharged from the side of the conveyor belt; the other is that the iron remover is in the same direction as the conveyor belt, and the iron is discharged from the front end of the material stream. It is used for extracting bulk iron materials, can be used for iron removing or iron recovering from coal, iron slag and steel slag, industrial waste and other materials.

Magnetic pulleys, also known as magnetic rollers, are available in both electromagnetic and permanent magnets. The permanent magnet pulley has a simple structure, no power consumption, reliable work, easy maintenance, and wide application. 1 Equipment structureBarium ferrite constitutes a multi-pole magnetic system with a magnetic wrap angle of 360 degrees, and a rotating cylinder made of a non-magnetic material is placed outside the magnetic system. 2 Magnetic system and magnetic field characteristicsWhen the material size of the treated material is less than 20mm, the alternating polarity is beneficial to improve the beneficiation efficiency. 3 Beneficiation process ore material evenly and constantly feed on the belt, when the ore passes through the magnetic pulley, the non-magnetic or weak magnetic ore particles are separated from the belt surface by centrifugal force and gravity; while the strong magnetic particles attracted to the belt by the action of the magnetic force and is carried by the belt to the lower part of the magnetic pulley. After the belt away the magnetic pulley, the magnetic force of the magnetic ore particles is weakened and falls into the magnetic product tank. The yield and quality of the product are adjusted by the position of the separation baffle mounted under the magnetic pulley.

4 Application Pre-selection for big size (10~120mm) strong magnetic ore, it usually be installed after the coarse crushing operation, separates the surrounding rock. In some concentrating plants, the magnetic pulley is installed between the fine crushing process and the grinding process, picking up part of the tailings, which can reduce the amount of ore and improve the grade. In the operation of the hematite ore roasting, the roasting quality is controlled by a magnetic pulley, so that the ore which is not sufficiently reduced is separated by a magnetic pulley and returned to the roasting furnace for magnetization roasting.

Drum magnetic separator main parts: Permanent magnet fixed magnetic system, feeding part (upper or lower feeding), discharge part, transmission and frame. 1 Structure-The cylinder is made of 2mm FRP and the surface is coated with a layer of wear-resistant rubber. The magnetic system consists of a barium ferrite permanent magnet block with a magnetic envelope angle of 270 degrees. The polarity of the magnetic poles alternates in the circumferential direction and the polarities are uniform along the axial direction. The main reason for the use of FRP for cylinders instead of stainless steel is to prevent the drum from heating due to eddy currents. The drum magnetic separator has two types of a single cylinder and double cylinder. The sorting length of the single-cylinder can be adjusted by the position of the baffle. The double-barrel machine can adjust the magnetic system declination to adapt to the needs of different sorting processes (concentrating or scavenging).

2 Beneficiation process The fine dry ore particles are firstly fed into the upper drum by the electric vibrating feeder, the magnetic ore particles are attracted on the cylinder surface and be discharged. The non-magnetic ore particles are thrown away from the cylinder surface by gravity and centrifugal force, and enter the lower drum for sorting. The non-magnetic ore particles enter the tailings trough, the rich aggregate enters the concentrate tank.

3 Applications Dry tye separation for fine-grained strong magnetic ore; Removing magnetic impurities and purifying magnetic materials from powdery materials, widely used in metallurgy, machinery, chemical, electric power, building materials and so on. Foreign dry-type weak magnetic cylinder magnetic separators include the former Soviet Unions cylindrical magnetic separator and the Sala Mortsell magnetic separator.

Permanent magnetic cylinder magnetic separator main parts: cylinder, magnetic system, sorting tank, feeding port, discharging and overflowing part. The cylinder can transport the adsorbed magnetic particles and prevent the slurry from immersing in the magnetic system. The cylinder and end cap are made of non-magnetic, high resistivity and corrosion-resistant materials. The tank in the magnetic field is made of austenitic stainless steel and is lined with synthetic material to prevent wear. Adding auxiliary magnetic pole to the gap of the main magnetic pole of the permanent magnetic cylinder magnetic separator, which can increase the magnetic field strength and the depth of action, and improve the production capacity and the sorting effect. The wet cylindrical magnetic separator has three tank structures: a forward flow, a reverse flow, and a semi-reverse flow.

The magnetic desilting tank is also called a magnetic dewatering tank. It is a dressing device that combines gravity and magnetic effect, widely used in the magnetic separation process to remove slime and fine-grained gangue, and also as a concentrator before filtration. Advantages of simple structure, no moving parts, convenient maintenance, simple operation, large processing capacity and good beneficiation effect.

In the magnetic desilting tank, the forces that the ore particles receive are gravity, magnetic force and water flow force. Gravity causes the ore particles to settle, and the magnetic force accelerates the sedimentation of the magnetic ore particles and adheres on the surface of the magnetic system. The rising water flow can prevent the sedimentation of the non-magnetic fine-grained gangue and the slime, and cause them to flow into the overflow. Thus, separate from magnetic ore particles from gangue. The ascending water flow can also make the magnetic ore particles loose, flush out and improve the concentrate grade.

In order to improve the beneficiation effect of the magnetic desilting tank, the ore particles are pre-magnetized before being selected, so that the fine-grained ferromagnetic materials are condensed into larger magnetic agglomerates. The sedimentation velocity of the magnetic agglomerates is faster than that of the non-magnetic particles, which is conducive to subsequent magnetic deliming and the like.

The demagnetizer disperses the ferromagnetic agglomerates. The commonly used demagnetizer structure is shown in the figure below. It is a tower-shaped coil that is placed on a non-magnetic material tube and works by alternating current. When the ferromagnetic mass passes through an alternating magnetic field whose magnetic field strength is changed from large to small, the magnetic particle has repeatedly magnetized a plurality of times, so that the magnetic energy product of the magnetic particle is smaller than once, and finally, the residual magnetism is lost.

ultimate guide to ore washing - jxsc machine

Ore washing is the process of by the use of water or mechanical force to agitate and scrub raw ore, wash and separate the clay from ore. The alluvial ore deposits ( like gold, platinum, tungsten, tin ) and other minerals such as lead, copper, iron and manganese which are deeply oxidized and weathered, usually need to be washed to remove some gangue or clay before crushing or beneficiation.

1. The washing process is often as preliminary preparation before the crushing and other beneficiation steps. Washing mud and separating the coarse waste rock can increase the overall efficiency, and reduce the machine wear.

3. Some ores slime and rocks are very different in terms of washability (such as floatability). Separation of ore slime and ore rock by washing process can obtain a better flotation effect. In this case, although washing is an auxiliary process, it has a significant impact on the entire production process.

The washability of ore is related to clay plasticity, water content, expansibility, permeability, and ore grain size composition. The smaller the plasticity of the clay, the stronger the expansion and permeability, the easier the ore is washed. The more the content of the rock materiale, the greater the impact agitation in the ore washing, and the more rapid the washing.

Add a high-pressure water pipe on the grizzly screen, vibrating screen, rotary screen, and the like ore screening machine, simultaneously do screening and washing. Ore washer machines have spiral washing machines, trommel scrubber machines, hydraulic washing sieve, cylinder washer, and trough washer.

Main parts of hydraulic washing screen: high pressure water gun, flat screen, overflow screen, inclined screen and large material screen. The flat screen and the inclined screen are about 3m wide, the flat screen length is 2~3m, the inclined screen length is 5~6m, the inclination angle is 20~22, and the large material screen tilt angle is 40~45. The overflow screen on both sides is perpendicular to the plane screen, and the screen strip is made of round steel of 25 ~ 30mm, and the spacing is generally 25 ~ 30mm. The hydraulic washing screen has a simple structure, large production capacity, and easy operation. Disadvantages: The water gun requires high water pressure and high power consumption; it has a low ability to break up small agglomerates.

vibrating screen product Mine use vibrating screens often adopts double-layer screens for screening medium and fine crushed ore. Add a high-pressure water flushing device on the fixed screening machine. The flushing water pressure is generally 0.2-0.3 MPa, and the water consumption per ton of ore is 1 ~ 2 m3. When the raw ore contains little mud and the cohesiveness is not strong, the use of such combination can meet the requirements of washing.

Cylinder trommel screen product Its cylinder is made of steel, woven mesh, or steel rods. A high pressure flushing water pipe is arranged in the longitudinal direction of the cylinder. With the rotation of the cylinder screen, the ore blocks are turned over and collided with each other, and the ore and clay dispersed. Built in impeding plates, chains can enhance the washing effect. The diameter of the cylinder is 1. 0~3.0m, the length is 3. 0~ 7.5m, the rotation speed of the cylinder is 15-30r/min, and the production capacity is 30~400t/h.

Trommel screening attrition scrubber Trommel screening attrition scrubber is suitable for handling medium washable ores up to 300 mm. The cylinder barrel of attrition scrubber is non-porous, the cylinder and the inner wall are provided with manganese steel or rubber lining, and the lining plate has ribs to form a spiral with the pitch gradually increasing toward the discharge end, which can make the material disperse and the material is moved towards the discharge end. The cylinder is rotated by the friction of the metal roller or the rubber tire.

Usually, the attrition scrubber need a fill rate of up to 25%. The ore and water enter the cylinder barrel at the same time from the feed port, reaching a certain concentration (solid mass fraction of 40% ~ 50%), so that it has sufficient fluidity. At the same time, a fixed nozzle water pipe can be disposed in the body of the scrubbing machine, and the water pressure is generally 0.1 to 0.2 MPa.

For easy-to-clean ore, the scrubber should use a lower speed (3o% 4o% critical speed), for the haigh plastic clay ore, the scrubber should use a high speed (70% ~ 80% critical speed). When the cylinder rotates, the material forms a waterfall movement in the scrubber, causing the ore to fall off and generate strong friction, forcing the disintegration of the highly plastic clay material. Therock material flushed by the high pressure water is discharged from the discharge port along with the slurry flow, and flows into the cantilever tapered cylindrical sieve installed on the scrubber to achieve sufficient separation of the mud and the rock material.

The structure of the trough washer is similar to that of a spiral classifier in that it has two long axes in a nearly semi-circular chute with discontinuous agitating blades. The apex of the blade is a spiral, the diameter of the spiral is 800mm, and the pitch is 300mm. The two spirals rotate in opposite directions, and the upper blades are all rotated outward. The slurry is fed from the lower end of the tank, and the cement of the ore is cut, scrubbed, and washed by the high-pressure water fed from the upper end, and the clay and the nugget are released. The clay forming slurry is discharged from the lower overflow tank, and the coarse material is pushed by the blades and discharged from the discharge port at the upper end of the tank.

The trough type washing machine has strong cutting and scrubbing ability, and has strong ability to break up small mud masses. It is suitable for the treatment of difficult to wash ore with less ore density, medium grain size and more mud. It has high processing capacity and high washing efficiency; the disadvantage is that the size of the ore washed is limited, generally not more than 50mm, otherwise the spiral blade is easily broken or even broken.

The trough washing machine with the specification of 6660mm x 1500mm has a tank volume of 6m3. The capacity of the slope alluvial tin mine is 800~1100t/d, and the water consumption per ton of ore is 4~6m3.

Spiral classifier product Spiral classifier can be used as a ore washer. But because it is not very strong in breaking and dispersing, it is mainly used for processing slime and sand products discharged from other ore washing equipment and further removing the mud.

There are basically two types of ore washing processes: The first is ore washing + slime and rock separating process, consisting of ordinary screening machinery (grizzly sieve, vibrating screen, trommel screen, etc.) and spiral classifier; The second is the process consisting of specialized washing equipment.

The former ore washing + slime and rock separating process is usually combine with crushing circuit, the screening equipment is play role both in crushing & grinding plant, and washing & screening plant, saves cost. It is suitable for treating ore with little amount, low plasticity and little agglomeration clay.

However, for those ore with more clay, high plasticity and agglomerate, it is necessary to use special washing equipment, and it is necessary to carry out 2 or even 3 times of washing to separate the clay from the ore.

Behind the washing process, there often followed by slime concentration operation, mainly using sloping plate grading thickener, deep cone thickener, vertical sand silo and other equipment, and the overflow water from the concentrated operation returns to the washing plant.