mineral processing spirals working principle

hydrocyclone working principle

The third type of classification used in mining is the Hydrocyclone, commonly called a Cyclone. Unlike the others it has no moving parts and is worked in conjunction of another piece of equipment, a pump. To understand the Hydrocyclone Working Principle we must first know its components. Beginning at the top, there is the OVERFLOW DISCHARGE.

Unlike the rake and spiral classifiers, the overflow of the cyclone is the exit point for the fine material instead of the other way around as it is in the case of the other two. Extending from the overflow discharge into the body, which is the feed entry point of the cyclone, is the VORTEX FINDER.

This is simply a length of pipe, its purpose is to provide a point of separation between the coarse and fine material. A better explanation will be possible once we begin explaining how it works. Next in our list of cyclones components is the UPPER and LOWER CONE, not all hydrocyclones havethis section divided into two cones. Some are designed thisway do to make repairs easier, and to isolate wear points, Their function is to help create a VORTEX.

This is done by guiding the slurry to the underflow at the same time presenting a smooth surface that will not restrict the generation of the CENTRIFUGAL FORCE that makes classification possible. Connected to the lower cone is the APEX. The apex is the discharge point of the cyclone, this discharge is referred to as the UNDERFLOW. The material that exits at this point will be the material that requires further grinding. The last part of the cyclone is the cyclone SKIRT. It is there only to limit spillage and splashing it isnt important to the operation of the cyclone.

I would suppose you are asking yourself, why and how does this piece of equipment separate the different sizes of rock? To answer that, we have to get into the operational theory of the cyclone. To start with, the slurry is directed into the cyclone along the wall of the body. Due to the ore being pumped, the slurry has VELOCITY. It is this velocity and point of entry helps in creating a spiral path around the outside of the body, the upper and the lower cone.

The entrance to the cyclone was designed this way to allow the incoming feed to help generate and not interfere with the spiral path that the ore must take inside the cyclone. The centrifugal force (the central Hydrocyclone Working Principle) that is generated by this spin, forces the bigger particles outwards towards the wall of the cyclone. If you were able to do a cross section of a cyclone while it is operating, you could see that the ground rock will become finer the closer that you get to the centre of the cyclone.

In all hydrocyclones there are two outlets, one for thecoarse material, this is the APEX, and the other for the finematerial, which is the VORTEX FINDER. The purpose of the Vortex finder is to separate the fine material from the coarse as it spirals around the vortex. The WIDTH of theVortex finder will determine how far into the coarsermaterial the separation point will be.

The Volume of slurry that is being fed into the cyclone must not exceed the capacity of these two outlets that allow it to escape. The size of the apex and the vortex finder is crucial. If the apex of the cyclone, like the size of the drain in your sink, is made smaller it wont allow as much slurry out of the underflow of the cyclone. This will cause the vortex to be smaller the internal volume of the slurry inside the cyclone will be greater and the amount of material that the vortex finder separates to become part of the overflow will be increased. As it is the DISTANCE across the vortex finder that determines where in the vortex the ore flow is separated at, the SIZE OE THE APEX will determine the degree of classification that the ore will be subjected to.

The size of the apex in relationship with the volume of slurry that is being fed to the cyclone, will create and maintain the PRESSURE NECESSARY to force the fine material out of the cyclone. The greater the pressure the greater the volume of overflow. To increase the overflow requires either a higher volume fed to the cyclone or a smaller underflow discharge opening. As the pressure in the cyclone climbs the amount of coarser material in the overflow increases. The reason that this pressure is generated is because the volume of the feed is greater than apex discharge capacity. The pressure is generated as the volume of slurry is built up over the apex.

These three factors then become your operating Variables when dealing with cyclones, APEX SIZE, the SIZE of the VORTEX FINDER, and the VOLUME of the feed. The CYCLONE PRESSURE becomes a control indicator for the adjustment of the apex size and the volume of the feed. The vortex finder is a FIXED VARIABLE, meaning that it can be changed to affect the sizing of the overflow, but not as a normal operating practice. The cyclone must be removed from service and taken apart to make that adjustment.

If the variables become unbalanced to the point where the pressure is too high, the cyclone will overload. What this means is that when a vortex is generated, an air column is formed in the center of the vortex. If this air column collapses, the velocity of the spiral will decrease far enough to lose the centrifugal force that causes the ore to classify. As the internal pressure of the cyclone represents the volume of slurry that is in the cyclone it only follows that the reason that the air column should collapse is that there isnt room left in the cyclone for the air.

If the variables become unbalanced in the opposite extreme then there wont be enough pressure to cause an overflow. Either the volume will be too low or the apex size too large. This will result in all of the feed being discharged out of the underflow. By what you have just learned it is apparent that to maintain an even pressure on the cyclone is very important. If the cyclone is dependent on pressure to function effectively then a constant pressure would ensure positive control over the classification of the ore. This means the pump that feeds the hydrocyclone is very important to the effective working of that hydrocyclone.

To understand how pumps work we will have to leavetheir relationship to cyclones until we have discussed their components and functions. Once we have finished discussing the pumps by themselves, we will come back to this relationship and explain the other variables that effect the performance of these two machines.

gravity spiral concentrator working principle

The gravity spiral circuit is designed to extract and concentrate coarse gold from the recirculating load in the mill grinding circuit and hence prevent a build up within that circuit and the eventual escape of some of that gold into the C.I.L. tanks and thereon into the final tails. (See fig. 4)

For the spirals to work efficiently the feed supply must have consistent characteristics and be of a constant rate. Variations in the flow rate, the feed size distribution and percentage solids will have adverse effects upon separation. Generally the solids tonnage should give adequate loading of the concentrate and middlings areas and the pulp density should be low enough to ensure mobility of particles in these areas. BUY SPIRALS

Feed to the spirals may be adjusted by the moving of two splitter arms on either side of the cyclone underflow discharge box, this altering the volume of the feed passing over the splitter screen. (See fig. 5)

The feed may also be adjusted by varying the speed of the gravity feed pump. This is necessary when the mill feed has been dropped and it is impossible to get sufficient feed for the gravity pump by adjustment of the splitter arms. At such times the speed will need to be dropped and the water additionadjusted to provide optimum feed density.

The pulp density may be altered by the addition of water, before the splitter screen, in the gravity feed pump hopper or to the concentrate launder beneath the primary spirals. The latter option adjusts the density of the feed to the cleaner spiral only.

The static distributor (See fig. 6) at the head of the primary spirals ensures an accurate division of the pulp stream to the spirals. For maximum efficiency a constant head should be maintained in the head pot. The head can be adjusted by either altering the flow rate from the splitter screen and/or altering the annular gap between the head pot and the distributor body, by moving the head pot up or down as required.

Feed from the splitter screen passes down into the gravity feed pump hopper and from there it is pumped to the static distributor above six triplex type primary spirals. As the pulp passes down these spirals; separaration of particles occurs according to specific gravity and the heavier minerals progress to the inner profile while lighter minerals are forced towards the outer profile, along with most of the water and slimes. At the bottom of each spiral layer there are splitters which can be adjusted to ensure the optimum recovery of coarse gold. (See fig. 7)

The middlings and tailings from the primary spirals are directed to both the mill feed and the mill discharge pump. The proportion going to either may be adjusted so as to help achieve optimum grinding conditions.

The concentrate from the inner outlet of the cleaner spiral is fed directly on to the Wilfley table and the middlings and tailings report to the gravity sump pump which feeds into the mill discharge pump feed hopper.

The Humphreys Spiral Concentrator, which was invented by I. B. Humphreys and first used in 1943 for concentrating chromite in Oregon beach sands, consists of five or six spiral turns of a modified semicircular launder which is about the size of a conventional automobile tire. Feed enters the top spiral and the tailing discharges from the bottom one, while concentrate and middlings are cut off by outlet ports regularly spaced at each turn of the spiral, and the products passed through rubber hoses to common launders which run the full length of a bank of spirals. Wash water is supplied from a small wash-water channel paralleling the main channel.

Operating entirely by gravity flow and involving no mechanical parts, the separation of the heavy constituents of the feed is effected by the same centrifugal forces and flow gradients encountered in ordinary river or stream concentration.

A capacity of 38 tons per spiral was obtained in the 1000-ton per 24 hr. Oregon plant operating on about a minus 40-mesh feed and in the 5000-ton plant recently installed near Jacksonville to concentrate ilmenite 174 roughing, and 12 finishing spirals have replaced an installation of tables and flotation cells.

The Humphreys Spiral has been successfully applied to recovery of chromite from chrome sands, rutile, ilmenite, and zircon from sand deposits, tantalum minerals and lepidolite from their ores, gravity concentration of base metal ores and in the cleaning of fine coal.

How it works: Pulp is introduced at the top of the spiral and flows downward. As the pulp follows the spiral channel the light particles in the pulp stream move outward and upward into the fast flowing portion of the stream while the heavy particles move to the inner slow moving portion of the stream, where they are drawn off through concentrate ports.

Adjustable splitters allow any portion to be removed through the ports. Tailing is discharged at the bottom of the spiral. Spirals are usually installed in double units, two spirals to a frame, in rows of two to twelve. Feed is split evenly to all spirals. At one plant 21 rows of 12 spirals each are fed by one pump.

The Humphreys Spiral Concentrator is a simple, efficient gravity concentrator which effects a separation between minerals of the proper size range that have sufficient difference in their specific gravity.

This concentrator is a spiral conduit of modified semi-circular cross-section, with outlets for removal of concentrate and middling. Pulp is introduced at the top of the spiral. As the pulp follows the spiral channel, lighter particles in the pulp stream move outward and upward into the fast moving part of the pulp stream. The heavy particles move to the inner, slow moving portion of the stream, where they are drawn off through concentrate or middling outlets. Adjustable splitters allow any portion of the concentrate or middling to be diverted through the outlets. Tailing discharges from lower end of spiral. A full- size spiral is used for laboratory testing. Two arrangements are suggested for test work.

In the closed circuit test unit illustrated, although a full-size spiral is used, as little as 20 pounds of material will indicate the possibility of spiral concentration in a batch test. By removing measured quantities of products, and adding like amounts of feed in repeated steps, substantial samples may be taken for analysis and estimates of capacity. Results from this procedure, using 100 to 300 pounds of material, are close to pilot test results.

Another arrangement, also using a full-size spiral, is a small pilot plant, and is suitable for test work where a larger quantity of material can be handled. The storage tanks may be built on the job from drawings supplied. This unit allows continuous feeding of material and permits accumulation of concentrate and tailing in separate tanks, which may then be re-run as feed for second stage concentration or scavenging of tailing.

Spiral concentrators are modem, high capacity, low costunits developed for the concentration of low grade ores. Spirals consist of a single or double helical sluice wrapped around a central support with a wash water channel and a series of concentrate take-off ports placed at regular intervals along the spiral (Figure 17). To increase the amount of material that can be processed by one unit, two or more starts are constructed around one central support. New spirals have been developed that do not use wash water. These new units have modified cross sections and only one concentrate-take-off port, which is

rapid wear of the rubber lining and irregular wash water distribution resulted in major production problems. Although still in use, the Humphreys cast iron spirals have been largely superseded by a variety of other types, notably the fiberglass Reichert spirals and new, lightweight Humphreys spirals.

The processes involved in mineral concentration by spirals are similar for all models. As feed containing 25-35% solids by volume is fed into the channel, minerals immediately begin to settle and classify. Particles with the greatest specific gravity rapidly settle to the bottom of the spiral and form a slow-moving fluid film. Thus the flow divides vertically: one level is a slow-moving fluid film composed of heavy and coarse minerals; the other level, the remainder of the stream, is composed of lighter material and comprises the bulk of the wash water. The slow-moving fluid film, its velocity reduced by friction and drag, flows towards the lowest part of the spiral cross-section (nearest the central support) where removal ports are located. The stream containing the lighter minerals and the wash water develops a high velocity, and is thrust against the outside of the channel (Figure 18). Separation is enhanced by the differences in centrifugal forces between the two: the lighter, faster flowing material is forced outward towards the surface, and the heavier, slower material remains inward towards the bottom.

Spiral concentrators are capable of sustained recoveries of heavy minerals in the size range of 3 mm down to 75 microns (6 to 200 mesh). They are suitable for use as roughers, cleaners, or scavengers. Feed rates may vary from 0.5 to 4 tons per hour per start, depending on the size, shape, and density of the valuable material. Some factors that affect recovery are the diameter and pitch of the spiral, the density of the feed, the location of splitters and take-off points, and the volume and pressure of thewash water. Individual spirals are easily monitored and controlled, but a large bank of spirals requires nearly constant attention.

Advantages of spiral concentrators include low cost, long equipment life, low space requirements, and good recovery of fine material. They can also be checked visually to determine if the material is separating properly. For maximum operating efficiency, feed density should remain constant, the particle-size distribution of the feed should be uniform, and fluctuations in feed volume should be minimized. Spiral concentrators will tolerate minor feed variations without requiring adjustment. Spiral concentrators, like cone concentrators, are efficient, low-maintenance units that should be considered for any large- scale gravity separation system.

The newer Humphreys spirals are capable of recovering particles as small as 270 mesh (53 microns). In a test at CSMRI, a new Mark VII Reichert spiral recovered 91.3% of the free gold contained in the feed in a concentrate representing only 5.4% of the feed weight. The unit showed little decrease in gold recovery efficiency with material down to 325 mesh (45 microns) (Spiller, 1983).

spiral classifier for mineral processing

In Mineral Processing, the SPIRAL Classifier on the other hand is rotated through the ore. It doesnt lift out of the slurry but is revolved through it. The direction of rotation causes the slurry to be pulled up the inclined bed of the classifier in much the same manner as the rakes do. As it is revolved in the slurry the spiral is constantly moving the coarse backwards the fine material will flow over the top and be travelling fast enough to be able to work its way downwards to escape. The Variables of these two types of classifiers are The ANGLE of the inclined bed, this is normally a fixed angle the operator will not be able to adjust it.

The SPEED of the rakes or spirals, the DENSITY of the slurry, the TONNAGE throughput and finally the SETTLING RATE of the ore itself.To be effective all of these variables must be balanced. If the incline is too steep the flow of slurry will be too fast for the rakes or spirals to separate the ore. If the angle is too flat the settling rate will be too high and the classifier will over load. The discharge rate will be lower than the feed rate, in this case. The load on the rakes will continue to build until the weight is greater than the rake or spiral mechanism is able to move. This will cause the classifier to stop and is known as being SANDED UP. If the speed of the rakes or spirals are too fast, too much will be pulled, out the top. This will increase the feed to the mill and result in an overload in either the mill or classifier as the circuit tries to process the increased CIRCULATING LOAD.

The DENSITY of the slurry is very important, too high the settling will be hampered by too many solids. Each particle will support each other preventing the heavier material from quickly reaching the bottom of the slurry. This will not allow a separation to take place quickly. The speed at which the slurry will be travelling will be slow and that will hamper effective classification. Another variable is the TONNAGE. All equipment has a limit on the throughput that anyone is able to process, classifiers are no different. This and the other factors will have to be adjusted to compensate for the last variable, the ore itself. Every ore type has a different rate of settling. To be effective each of the previous variables will have to be adjusted to conform to each ones settling characteristics.

The design of these classifiers (rake, spiral, screw) have inherent problems, First, they are very susceptible to wear, caused by the scrubbing action of the ore, that plus all of the mechanical moving parts create many worn areas to contend with. The other problem that these classifiers have is that they are easily overloaded. An overloaded classifier can quickly deteriorate into a sanded-up classifier. Once that happens the results are lost operating time, spillage and a period of poor Mineral Processing and Separation performance.

Another mechanical classifier is the spiral classifier. The spiral classifier such as the Akins classifier consists of a semi-cylindrical trough (a trough that is semicircular in cross-section) inclined to the horizontal. The trough is provided with a slow-rotating spiral conveyor and a liquid overflow at the lower end. The spiral conveyor moves the solids which settle to the bottom upward toward the top of the trough.

The slurry is fed continuously near the middle of the trough. The slurry feed rate is so adjusted that fines do not have time to settle and are carried out with the overflow .liquid. Heavy particles have time to settle, they settle to the bottom of the trough and the spiral conveyor moves the settled solids upward along the floor of the trough toward the top of the trough/the sand product discharge chute.

spiral concentrators in mineral processing

Spiral concentrators are used for a number of mineral processing applications. They're extensively used to process heavy mineral sand deposits, including monazite, zircon, ilmenite and rutile deposits. More recently, spiral concentrators have been widely used to

Large mineral processing plants consist of hundreds of spiral concen trators, and the adjustment of splitters is time consuming, impractical and is in many casesontact us spiral classifier for mineral processing 911 metallurgistar 19, 2018 n mineral processing

Spiral Concentrators Some spiral concentrators especially those used in coal cleaning have the capability of removing the high density material at multiple positions in the vertical spiral Coal can consist of as much as 50 high density material compared to a ...

1/10/1985 International Journal of Mineral Processing, 15 (1985) 173--181 173 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands PRINCIPLES OF SPIRAL CONCENTRATION R. SIVAMOHAN and E. FORSSBERG Division of Mineral Processing ...

Chromium Spiral Concentrator Mineral Process Spral Degree Multotec mineral spiral concentrators allow for separation of fine heavy minerals in the size range 15 mm to 004 mm multotec hx3 and hx5 mineral spiral concentrators are used for chrome and iron ore while the sc range is typically used for gold copper iron ore .

Some spiral concentrators, especially those used in coal cleaning, have the capability of removing the high density material at multiple positions in the vertical spiral. Coal can consist of as much as 50% high density material, compared to a typical heavy mineral with only 5% to 10% high density content.

Spiral concentrators are used for a number of mineral processing applications. They're extensively used to process heavy mineral sand deposits, including monazite, zircon, ilmenite and rutile deposits. More recently, spiral concentrators have been widely used to

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Spiral separation uses a flowing film principle based on the size and specific gravity difference present in a mineral suite. When fed a dilute pulp mixture of minerals of different specific gravities, the lighter minerals are more readily suspended by the water and attain relatively high tangential velocities so that they climb toward the outer rim of the spiral trough.

Large mineral processing plants consist of hundreds of spiral concen trators, and the adjustment of splitters is time consuming, impractical and is in many casesontact us spiral classifier for mineral processing 911 metallurgistar 19, 2018 n mineral processing

Spiral concentrators are used for a number of mineral processing applications. They're extensively used to process heavy mineral sand deposits, including monazite, zircon, ilmenite and rutile deposits. recently, spiral concentrators have been widely used to recover fine coal as well as gold, iron ore.

Spiral Concentrator For Processing And Refining The Mineral Spiral Concentrators Mine Some spiral concentrators, especially those used in coal cleaning, have the capability of removing the high density material at multiple positions in the vertical spiral Coal can

Metallurgical ContentOptimum Operating Conditions of a Spiral ConcentratorThe Spiral' Static DistributorThe Primary Spirals SeparatorThe Cleaner Spiral SeparatorMaintenance of the SpiralsHumphreys Spiral ConcentratorWhen to use a Gravity Spiral ConcentratorHumphreys Spiral Concentrator CapacitySpiral Concentrator The gravity spiral circuit is designed to extract and .

The fine mineral spiral series is used for fine feed with particles in the range of 30-150 microns WW Series Utilises wash water addition for enhanced grade control in specific applications (i.e. iron ore, mineral sand) HC Series These super-high capacity spirals

Large mineral processing plants consist of hundreds of spiral concen trators, and the adjustment of splitters is time consuming, impractical and is in many casesontact us spiral classifier for mineral processing 911 metallurgistar 19, 2018 n mineral processing

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spiral for mineral processing Spirals are widely used in mineral processing as a method for pre-concentration and have proven to be metallurgically efficient and cost-effective. As the mineral stream is fed from the top of the spiral, a combination of forces act on

adding ridges on the sluice at an angle to the direction of flow. Typical spiral concentrators will use a slurry from about 20%-40% solids by weight, with a particle size somewhere between 1.5-.075 mm (17-340 mesh), though somewhat larger particle sizes are sometimes used.

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Chromium Spiral Concentrator Mineral Process Spral Degree Multotec mineral spiral concentrators allow for separation of fine heavy minerals in the size range 15 mm to 004 mm multotec hx3 and hx5 mineral spiral concentrators are used for chrome and iron ore while the sc range is typically used for gold copper iron ore .

Chromium Spiral Concentrator Mineral Process Spral Degree Multotec mineral spiral concentrators allow for separation of fine heavy minerals in the size range 15 mm to 004 mm multotec hx3 and hx5 mineral spiral concentrators are used for chrome and iron ore while the sc range is typically used for gold copper iron ore .

Mineral Spiral Concentrators Multotec Mineral Processing. Mineral spiral concentrators separation of fine heavy minerals has been made easier with multotecs ranges of mineral spiral concentrators our gravity concentration products separate fine heavy mineral sizes from 15 mm to 004 mm and are ideal for iron ore chrome mineral sands and high density ores.

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Spiral Concentrator For Processing And Refining The Mineral Spiral Concentrators Mine Some spiral concentrators, especially those used in coal cleaning, have the capability of removing the high density material at multiple positions in the vertical spiral Coal can

Multotecdesigned spiral concentrators are used across the world in coal gold iron ore mineral sands platinum and chrome processing plants and other minerals As a turnkey supplier of gravity concentration equipment across the world Multotec can deliver endtoend ...

spiral concentrators for silica sand Spiral Concentrator Free Essays PhDessaySingle Start Spiral 1 2 Applications of Spirals Spiral concentrators have over numerous years found many varied applications in mineral processing but perhaps their most extensive usage ...

Because the spiral classifier is often used in the classification of gold mineral processing plants in China, the former configuration is more used in China. However, hydrocyclones are often used for classification abroad, therefore, Knelson Concentrator is usually used to separate coarse gold from underflow by hydrocyclones.

Spiral Concentrator For Processing And Refining The Mineral Spiral Concentrators Mine Some spiral concentrators, especially those used in coal cleaning, have the capability of removing the high density material at multiple positions in the vertical spiral Coal can

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spiral classifier

Spiral Classifier is a traditional type of classification equipment, mainly for metal mineral processing for the slurry density and particle size on the wet grade, mining operations could also be used in the flow desliming.

it is hard to get very fine product, especially for product with -200 mesh over 90%; It is not easy to automate control it, and the classification efficiency is not high; It needs a large space for installation.

spiral classifier,mineral processing spiral classifier,spiral sand classifier - hxjq

According to the number of spiral, spiral classifier can be divided into single spiral classifier and double spiral classifier; according to the submerged overflow surface depth of spiral blade, it can be divided into high weir type and submerged types.

Spiral classifier is widely used in mineral processing plant to form closed cycle way with ball mill for split mineral sand, or used in gravity concentrator to grade ore and fine mud, or the size grading of slurry in ore dressing process as well as desliming, dehydration and other operations in ore washing operations. It has the characteristics of simple structure, reliable work, convenient operation, etc.

Spiral classifier is a type of classifying machine that classifies materials based the principle that the solid particles with different sizes and proportions have different falling speed in the liquid, and fine ore particles float in the water and coarse ore particles sink to the bottom of the chute and coarse ore particles are pushed by the spiral to the upper part and discharged. Hongxing spiral classifier is able to filter the powdery particle crushed by the grinding mill and whirl the coarse particles with the spiral to the feeding mouth of the grinding mill and discharge the filtered fine particles.

Model Spiral Diameter (mm) Trough Length (mm) Spiral rotate speed (r/min) Processing capacityt/d Motor Power kw Dimensions mm Total weight t Sand -return Overflow For driving For lifting Length Width Height FG-3 300 3000 12-30 80-150 20 1.1 ---- 3850 490 1140 0.7 FG-5 500 4500 8-12.5 135-210 32 1.1 ---- 5430 680 1480 1.9 FG-7 750 5500 6-10 340-570 65 3 ---- 6720 980 1820 3.1 FG-10 1000 6500 5-8 675-1080 110 5.5 ---- 7590 1240 2380 4.9 FC-10 8400 675-1080 85 7.5 ---- 9600 1240 2680 6.2 FG-12 1200 6500 4-6 1170-1870 155 7.5 2.2 8180 1570 3110 8.5 FC-12 8400 1170-1870 120 7.5 2.2 10370 1540 3920 11.0 2FG-12 6500 2340-3740 310 15 4.4 8230 2790 3110 15.8 2FC-12 8400 2340-3740 240 15 4.4 10370 2790 3920 17.6 FG-15 1500 8300 4-6 1830-2740 235 7.5 2.2 10410 1880 4080 12.5 FC-15 10500 1830-2740 185 7.5 2.2 12670 1820 4890 16.8 2FG-15 8300 2280-5480 470 15 4.4 10410 3390 4080 22.1 2FC-15 10500 2280-5480 370 15 4.4 12670 3370 4890 30.7 FG-20 2000 8400 3.6-5.5 3290-5940 400 11-15 3 10790 2530 4490 20.5 FC-20 12900 3210-5940 320 11-15 3 15610 2530 5340 28.5 2FG-20 8400 7780-11880 800 22-30 6 11000 4600 4490 35.5 2FC-20 12900 7780-11880 640 22-30 6 15760 4600 5640 48.7 FG-24 2400 9130 3.67 6800 580 15 3 11650 2910 4970 26.8 FC-24 14130 6800 490 18.5 4 16580 2930 7190 41.0 2FG-24 9130 13600 1160 30 6 12710 5430 5690 45.8 2FC-24 14130 13700 910 37 8 17710 5430 8000 67.9 2FG-30 3000 12500 3.2 23300 1785 40 8 16020 6640 6350 73.0 2FC-30 14300 23300 1410 ---- ---- 17091 ---- 8680 84.8 Model Spiral Diameter (mm) Spiral rotate speed (r/min) FG-3 300 12-30 FG-5 500 8-12.5 FG-7 750 6-10 FG-10 1000 5-8 FC-10 FG-12 1200 4-6 FC-12 2FG-12 2FC-12 FG-15 1500 4-6 FC-15 2FG-15 2FC-15 FG-20 2000 3.6-5.5 FC-20 2FG-20 2FC-20 FG-24 2400 3.67 FC-24 2FG-24 2FC-24 2FG-30 3000 3.2 2FC-30

gravity separation

Our Australian based head office houses the world's largest spiral manufacturing facility and produces over 20,000 starts annually. In 2010/11, we manufactured HC33 and WW6 spirals for ArcelorMittal's Mont Wright mining operations in Canada to deliver the largest single spiral order in our history.

gold centrifugal concentrator - mineral processing

The centrifugal concentrator rotates at a high speed, generating a high G force, which can separate small gravity recovery gold (less than 50 microns), which was of previously unrecoverable with traditional mineral jigs, spiral separator, and gravity tables.In recent years, the application of centrifugal force has proved to be an effective technology for recovering fine and heavy minerals. The centrifugal force acting on the mineral particles can reach 50 times its own gravity, thus significantly increasing the sedimentation speed of the particles. As the intensity of the centrifugal force increases, the size of the particles that can be captured becomes finer.

The centrifugal concentrator can be used to recover the tailings of chromite, gold, scheelite and other heavy minerals, so as to make better use of mineral concentrates. Their operating and equipment costs are relatively low. Thanks to its less environmental impact and good recovery of fine-grained minerals, the application of centrifugal concentration has become increasingly important worldwide.

The gold centrifugal concentrator is a gravity-enhancing device. The feed slurry is introduced into a rotating drum, and the impeller rotates to form a high-gradient centrifugal field. The ore particles flow on the inner wall of the rotor and are continuously layered and deposited on the smooth inside the centrifuge wall.The lighter particles outside the bed are removed from the rotor assembly due to their lower specific gravity or smaller size. Heavy particles remain in the concentration zone, where the concentrate is cleaned with fluidized water.A rotor spins the bowl, which throws the feed coming into the center against the walls of the bowl. Light and fine particles are carried out of the bowl with the tailings while heavy and coarse particles are collected and removed from the bowl. Industrially they can operate as batch or continuous units, with pores opening intermittently to collect concentrate.

principles of spiral concentration - sciencedirect

The different stages of the mechanism of concentration in spiral concentrators are discussed. The significance of many design and operational variables and their interrelationships are examined. The various areas where the spiral concentrators are applicable are presented.

mineral processing | metallurgy | britannica

Mineral processing, art of treating crude ores and mineral products in order to separate the valuable minerals from the waste rock, or gangue. It is the first process that most ores undergo after mining in order to provide a more concentrated material for the procedures of extractive metallurgy. The primary operations are comminution and concentration, but there are other important operations in a modern mineral processing plant, including sampling and analysis and dewatering. All these operations are discussed in this article.

Routine sampling and analysis of the raw material being processed are undertaken in order to acquire information necessary for the economic appraisal of ores and concentrates. In addition, modern plants have fully automatic control systems that conduct in-stream analysis of the material as it is being processed and make adjustments at any stage in order to produce the richest possible concentrate at the lowest possible operating cost.

Sampling is the removal from a given lot of material a portion that is representative of the whole yet of convenient size for analysis. It is done either by hand or by machine. Hand sampling is usually expensive, slow, and inaccurate, so that it is generally applied only where the material is not suitable for machine sampling (slimy ore, for example) or where machinery is either not available or too expensive to install.

Many different sampling devices are available, including shovels, pipe samplers, and automatic machine samplers. For these sampling machines to provide an accurate representation of the whole lot, the quantity of a single sample, the total number of samples, and the kind of samples taken are of decisive importance. A number of mathematical sampling models have been devised in order to arrive at the appropriate criteria for sampling.

After one or more samples are taken from an amount of ore passing through a material stream such as a conveyor belt, the samples are reduced to quantities suitable for further analysis. Analytical methods include chemical, mineralogical, and particle size.

Even before the 16th century, comprehensive schemes of assaying (measuring the value of) ores were known, using procedures that do not differ materially from those employed in modern times. Although conventional methods of chemical analysis are used today to detect and estimate quantities of elements in ores and minerals, they are slow and not sufficiently accurate, particularly at low concentrations, to be entirely suitable for process control. As a consequence, to achieve greater efficiency, sophisticated analytical instrumentation is being used to an increasing extent.

In emission spectroscopy, an electric discharge is established between a pair of electrodes, one of which is made of the material being analyzed. The electric discharge vaporizes a portion of the sample and excites the elements in the sample to emit characteristic spectra. Detection and measurement of the wavelengths and intensities of the emission spectra reveal the identities and concentrations of the elements in the sample.

In X-ray fluorescence spectroscopy, a sample bombarded with X rays gives off fluorescent X-radiation of wavelengths characteristic of its elements. The amount of emitted X-radiation is related to the concentration of individual elements in the sample. The sensitivity and precision of this method are poor for elements of low atomic number (i.e., few protons in the nucleus, such as boron and beryllium), but for slags, ores, sinters, and pellets where the majority of the elements are in the higher atomic number range, as in the case of gold and lead, the method has been generally suitable.

A successful separation of a valuable mineral from its ore can be determined by heavy-liquid testing, in which a single-sized fraction of a ground ore is suspended in a liquid of high specific gravity. Particles of less density than the liquid remain afloat, while denser particles sink. Several different fractions of particles with the same density (and, hence, similar composition) can be produced, and the valuable mineral components can then be determined by chemical analysis or by microscopic analysis of polished sections.

Coarsely ground minerals can be classified according to size by running them through special sieves or screens, for which various national and international standards have been accepted. One old standard (now obsolete) was the Tyler Series, in which wire screens were identified by mesh size, as measured in wires or openings per inch. Modern standards now classify sieves according to the size of the aperture, as measured in millimetres or micrometres (10-6 metre).

In order to separate the valuable components of an ore from the waste rock, the minerals must be liberated from their interlocked state physically by comminution. As a rule, comminution begins by crushing the ore to below a certain size and finishes by grinding it into powder, the ultimate fineness of which depends on the fineness of dissemination of the desired mineral.

In primitive times, crushers were small, hand-operated pestles and mortars, and grinding was done by millstones turned by men, horses, or waterpower. Today, these processes are carried out in mechanized crushers and mills. Whereas crushing is done mostly under dry conditions, grinding mills can be operated both dry and wet, with wet grinding being predominant.

Some ores occur in nature as mixtures of discrete mineral particles, such as gold in gravel beds and streams and diamonds in mines. These mixtures require little or no crushing, since the valuables are recoverable using other techniques (breaking up placer material in log washers, for instance). Most ores, however, are made up of hard, tough rock masses that must be crushed before the valuable minerals can be released.

In order to produce a crushed material suitable for use as mill feed (100 percent of the pieces must be less than 10 to 14 millimetres, or 0.4 to 0.6 inch, in diameter), crushing is done in stages. In the primary stage, the devices used are mostly jaw crushers with openings as wide as two metres. These crush the ore to less than 150 millimetres, which is a suitable size to serve as feed for the secondary crushing stage. In this stage, the ore is crushed in cone crushers to less than 10 to 15 millimetres. This material is the feed for the grinding mill.

In this process stage, the crushed material can be further disintegrated in a cylinder mill, which is a cylindrical container built to varying length-to-diameter ratios, mounted with the axis substantially horizontal, and partially filled with grinding bodies (e.g., flint stones, iron or steel balls) that are caused to tumble, under the influence of gravity, by revolving the container.

A special development is the autogenous or semiautogenous mill. Autogenous mills operate without grinding bodies; instead, the coarser part of the ore simply grinds itself and the smaller fractions. To semiautogenous mills (which have become widespread), 5 to 10 percent grinding bodies (usually metal spheres) are added.

Yet another development, combining the processes of crushing and grinding, is the roll crusher. This consists essentially of two cylinders that are mounted on horizontal shafts and driven in opposite directions. The cylinders are pressed together under high pressure, so that comminution takes place in the material bed between them.