multi gravity mozley separator drum
The 911MPEC900 Laboratory or Pilot plant multi-gravity separator (MGS) is a compact and mobile unit suitable for laboratory or on-site pilot plant investigation into the continuous separation of minerals of different specific gravities in liquid suspension.
The Laboratory multi-gravity separator (single drum design) formally known as the Richard MozleyC-900 (MGSC-900). We are also please to offer the new Pure Select system inaddition to the conventional scraper system. The (MGSC-900) uses the same principles of separation and mechanicaltechniques as the larger double drum MGS C-902 with 3.5 to 4 tons per hourcapacity and we confirm that the performance of the (MGSC-900) laboratorymachine will be equal to that obtained from the larger field MGS C-902, assumingthe same feed and equipment set-up.
The (MGSC-900) is a premiumseparator designed to separate and upgrade the finest minerals and metals onspecific gravity difference. The optimum feed to the (MGSC-900) machine willtypically comprise solids in the range of 5 to 120 microns. It uses a similarprinciple of separation as a shaking table but enhances the degree of separation and the capacity of the machine multiple times by wrapping the normallyhorizontal separating surface of a shaking table into a conical drum. When rotated this develops a force many times greater than gravity alone causing the finest particles to separate within the dynamic thin liquid film coating the inner surface of the drum. The speed of rotation and degree of shake can be adjusted to provide a high degree of selectivity in operation, enabling the (MGSC-900) machine toachieve the required grade and recovery of concentrate to meet the clients needs. Internal scraper blades convey the heavy concentrate to the front of the drum,while lighter material is washed to the back of the drum as a tails stream.
The MGS consists of a slightly tapered open ended drum that rotates clockwise (as viewed from the open end) while being shaken axially with a sinusoidal motion. Inside the drum is a scraper assembly that rotates in the same direction as the drum but at a slightly faster speed.
Feed slurry is introduced continuously from a position midway along the drum onto its internal surface via an accelerator ring launder. Washwater is added via a similar launder positioned near the open end of the drum.
As a result of the high centrifugal forces and the added shearing effect of the shake, the dense particles migrate through the slurry film to form a semisolid layer against the wall of the drum. The scrapers move the dense layer towards the open end of the drum where the layer discharges into the concentrate launder.
For full-scale production the 911MPEC902 Double Drum MGS is available. Extensive trials have demonstrated that this unit, measuring 4.7m x 1.5m x 1.8m high, will produce similar grade and recovery to the 911MPEC900 MGS while treating between 10 and 25 times the feed tonnage.
Where a continuous supply of feed slurry is available, or the feed is supplied via a pump from a stirred tank, connect a hose of suitable size (12.5mm ID), fitted with a control valve if necessary, from the feed supply to the left hand pipe on the feed/wash pipe unit.
Connection of electricity supply must be done by a competent electrician. Connect the electricity supply to the isolator fitted at the rear of the machine. Check motor rating plates to confirm correct electricity supply.
Electrical controls are mounted on a panel at the rear of the machine. The electrical enclosure and inverter are located within the body of the MGS and must not be adjusted by the user. The settings are adjusted during commissioning by a qualified person. For information the Lenze SMV frequency inverter manual is supplied as an addendum.
8. Refit belt to motor pulley 9. Set correct tension to layshaft drive belt 10. Tighten clamp bolt on layshaft drive motor mounting plate 11. Fit lower side panels 12. Check shake mechanism operates satisfactorily by pressing shake ON button 13. Switch off using either stop button and switch or the isolator
The rotational speed of the drum is controlled by a variable speed controller mounted below the layshaft, accessible on removal of the right hand panel. Speed is adjustable between 100 and 280 rpm using the rotary speed control (this is a ten turn potentiometer) mounted on the control panel.
These figures are correct where the electrical supply is 240 volts 50Hz. Calibration will vary with voltage frequency. On installation check the drum speed over a range of settings and if necessary plot a revised calibration chart similar to the one below.
The quantity of washwater required will normally depend on the density of the minerals treated. For lower SG minerals a flowrate of 2L/min may be sufficient whereas for high SG minerals a flowrate of 6L/min may be required.
Increased washwater gives a cleaner concentrate (dense fraction), but also results in increased loss of dense mineral to tailings. Solids of lower specific gravity (such as barytes) usually require less wash water than materials with higher specific gravity (such as cassiterite) or coarse solids.
Depending on the nature and particle size of the feed solids, throughput may vary between 50 and 200kg/hr. of dry solids. For finer solids (<75m) an acceptably clean concentrate with good recovery is usually produced with a throughput of 100kg/hr.
The MGS is a continuous processing separation machine and in order to achieve an accurate indication of its true performance it is preferable to use a test procedure which more closely simulates continuous operation. For this a minimum of 10kg of sample solids is required per test.
3. Carry out initial test running procedure- Section 5 4.Isolate From Electricity Supply 5. Loosen and remove four set screws 6. Remove upper launder 7. Using a water hose, thoroughly wash out all compartments and drum, ensuring that no residue remains from previous test runs. 8. Replace launder 9. Re-connect to electricity supply. 10. Place a sample bucket under the tailings discharge pipe, another under the concentrate discharge pipe and a third under the centre spillage discharge pipe. 11. Mix a minimum of 10 kg of dry sample with water to give a pulp with a density of between 30 to 50% solids w/w (volume will be 28 and 14 litres respectively). To ensure adequate dispersion of the solids it is advisable to add a dispersing agent (i.e. Sodium Polymetaphosphate). Ensure all lumps or agglomerates are fully dispersed. The solids must be kept in homogeneous suspension for the duration of the test using a mechanical stirrer.
12. Open the water valve below the rotameter and adjust to give a washwater flowrate of 3L/min. 13. Reconnect to electricity supply and switch on isolator. 14. Press shake starter button and switch on rotary drive to set the MGS in operation. 15. Set speed control to 555 (to give 200rpm). Leave the settings for shake speed and amplitude unaltered for the initial series of tests. Set tilt to approximately 4. Optimise the results by varying the settings (by trial and error) in subsequent test series. Keep settings for shake, amplitude and tilt angle constant in a test series while varying rotational speed and washwater flowrate. 16. Using a suitable pump (a peristaltic type is recommended) introduce the feed pulp into the MGS at a steady feed rate of 1 to 2 L/min. 17. Allow the MGS to run under steady feeding conditions until operation becomes completely stabilised. This usually takes between 2 and 5 minutes, depending on the nature of the sample and the grade of the heavy mineral present. Check buckets frequently and replace when they become full. 18. When conditions have become stabilised use clean buckets to simultaneously collect timed samples of concentrate and tailing products. Allow sufficient time to collect a reasonable quantity of concentrate (this may have a very low flowrate). Between 10 and 30 seconds is normally adequate. 19. After collecting the test products turn off the feed and allow the MGS to operate until the bulk of the remaining solids have discharged, either to drain or into the original buckets. 20. Turn off the washwater and stop the MGS. 21.Isolate From Electricity Supply 22. Remove upper launder. 23. Using a water hose wash all remaining solids from the launders and drum (inside and out) either to drain or into the original buckets. Rotate drum by hand while washing out to ensure removal of all solids. 24. The two samples required for full evaluation of the test will consist of
The MGS combines the centrifugal motion of an angled rotating drum (though not atsuch a high speed) of a Kelsey jig or Falcon Concentrator, with the oscillating motion of a shaking table, to provide an enhanced gravity separation, particularly suited to fineparticles. The principle of the separation in the MGS is based upon the above-mentioned forcesthat act on particles in a slurry stream being fed and are distributed onto the inside of the drums surface. With the aid of scrapers and wash water, the high SG particlesmigrate up the drum to discharge over the drums top lip, while the low SG particlesflow in the opposite direction and discharge over the lower drum lip (Fig. 8).
With more mining activity, the amount of waste materials readily increases in some countries. Storage of waste materials or tailings disposal has become a serious matter for the mining industry due to its growth. During the earlier concentration of valuable minerals in many plants, large volumes of tailings were produced and these tailings may be harmful to the environment (Ozkan et al, 2002). Therefore, it is important for some tailings to be investigated for both economic and environmental reasons in many countries.
Chromite is an important mineral used in metallurgy, chemistry, and refractory industries. Chromite ores contain a variety of gangue minerals such as serpentines and olivine. Therefore, some kind of concentration is required for beneficiation of chromites. The most commonly used beneficiation methods for chromite ores are the gravity methods, such as shaking table, jig, spiral, and Reichert cone. Magnetic separation is also used depending on the ore characteristics. Flotation is also used for the beneficiation of finely grained ores. With these conventional methods depending on the liberation particle size of the ore, significant amounts of fine chromites are lost to the tailings. For this reason, all of these methods are only partly successful in the fine particle size range (Gence, 1999).
Many investigators have reported the remarkably high value of chromites in the tailings of chromite concentration plants. A number of investigations have been run to determine the most economic process applicable to the fine tailings of Turkish concentration plants (Guney et al., 1999; Guney et al., 2001; Cicek et al., 2002; Ozdag et al., 1993).
There are approximately 2,700,000 tons of chromite tailings disposed containing approximately 20.7% Cr2O3 in the tailing dam of the Guleman-Sori/Turkey chromite concentration plant (Gence, 1999; Kaya, 2002). Conventional gravity separation devices usually lose efficiency in the finer size ranges. The multi-gravity separator is a concentration device designed to use several of the traditional gravity concentration techniques in one machine, allowing a separation of finer materials or materials with much closer specific gravity than any of the traditional methods (Chan et al., 1991; Chan et al., 1993; Goktepe, 2005). Typical applications of MGS include the scavenging of valuable metals or valuable minerals from tailings or slime streams; pre-concentration of heavy mineral sand or industrial minerals; upgrading flotation concentrates; concentrating base metal oxides, sulfides, and uranium from primary ores; and treatment of alluvial ores in general (Chan et al., 1991; Chan et al., 1993). The MGS has also been reported to have the potential to be a useful machine in the decontamination of fine metal minerals from abandoned mines, leaving a tailing with much reduced metal availability where conventional mineral processing techniques are not suitable (Wise et al., 1997; Traore et al., 1995). It was also reported that beneficiation of fine size celestite tailings by MGS is possible (Aslan et al., 1996).
In this study, the applicability of an enhanced gravity concentration technique and magnetic separation for beneficiation of fine chromite from the magnetic tailings of the Guleman-Sori/Turkey chromite concentration plant was investigated by using a multi-gravity separator and high-intensity induced-roll magnetic separator.
The multi-gravity separator (MGS) concentrates particles based on the combined effects of centrifugal acceleration and forces acting on a conventional shaking table. The laboratory/pilot plant scale C-900 MGS consists basically of a slightly tapered open-ended drum measuring 600 mm long with a diameter of 500 mm that rotates in a clockwise direction and is shaken sinusoidal in an axial direction. Inside the drum is a scraper assembly that rotates in the same direction but at a slightly faster speed (Chan et al., 1991; Chan et al., 1993; Aslan et al., 1997; Aslan et al., 1997; Ozbayoglu et al., 2002; Bhaskar et al., 2002; Patil et al., 1999). Feed slurry is introduced continuously midway onto the internal surface of the drum via a performed ring. Wash water is added via a similar ring positioned near the open end of the drum. As a result of the high centrifugal forces and the added shearing effect of the shake, the dense particles migrate though the slurry film to form a semi-solid layer against the wall of the drum. The scrapers convey this dense layer towards the open end of the drum where it discharges into the concentrate launder. The less dense minerals are carried by the flow of wash water downstream to the rear of the drum to discharge via slots into the tailings cleaner (Ozbayoglu et al., 2002; Bhaskar et al., 2002; Patil et al., 1999).
The parameters affecting the efficiency of separation on MGS are the drum speed (infinitely variable from 100 to 300 rpm), wash water (0 to 10 l/min), inclination (0 to 9), shake amplitude (10/15/20 mm), shake frequency (4.0/4.8/5.7 cps), and pulp density of the feed slurry (10% to 50% by weight)(Aslan et al.,1996).
The Carpco Model MIH 111-5 is a laboratory/pilot-plant dry high-intensity magnetic separator designed to separate moderately or weakly paramagnetic materials. This magnetic separator is also called a high-intensity induced-roll magnetic separator (HIRMS).
High-intensity induced-roll magnetic separator treats from 1 mm down to 74 m in size and boasts a capacity of up to 90 kg/h based on material having a bulk density of 1600 kg/m, variable magnetic field intensity up to 0.96 T, 127 mm diameter and 50.8 mm length laminated roll with variable speed 0-100 rpm (Ibrahim et al., 2002).
The separator places all materials in contact with the highest magnetic field at the zones of steepest magnetic gradient and utilizes magnetic force and gravity to capture weak magnetic particles. A turning induced magnetic roll is used to transport materials through the active area providing an opposing centrifugal force for separation of magnetic and non-magnetic materials. This technique is capable of efficiently removing weak magnetic materials as contaminants in non-magnetic products.
The sample used in tests was taken from the tailings dam of the Guleman-Sori/Turkey chromite concentration plant. The capacity of the plant was 6000 tons/year and the ore assays 30-33% Cr2O3. In the plant, a low-intensity and a high-intensity dry magnetic separator were used. The concentrate produced in this plant contains 42-43% Cr2O3. The chromite tailings disposed contain approximately 20.7% Cr2O3. The site was reported to have approximately 2,700,000 tons of chromite tailings disposed in the plant (Gence, 1999; Kaya, 2002).
To determine the mineralogical characteristic, a physical/chemical analysis of the same sample was carried out by Gence. A complete chemical analysis by Gence is shown in Table 1 (Gence, 1999). A sieve analysis was carried out to determine the size distribution of the feed sample, as shown in Figure 2. Each size fraction was analyzed chemically and examined microscopically to determine the metal distribution and point of chromite particles, respectively. The results are shown in Table 2. The sample used in this study contains 20.7% Cr2O3. The sample is composed of chromite (mostly in 53-600 m fraction) as valuable mineral, olivine (mostly in 25-275 pm fraction), feldspar (in 25-250 m fraction), and pyroxenes (in 25-150 m fraction).
From the microscopic study, it can be easily seen that sufficient liberation, which is above 95%, can be reached at -300 m particle size. Therefore, the sample was wet screened of 300 m to obtain suitable feed size for MGS tests. The fraction coarser than 300 m, which is too coarse to be handled by MGS, was ground to less than 300 m particle size by ball mill.
The batch tests were conducted in this investigation in The Mineral Processing Laboratory of Cumhuriyet University-Turkey. MGS tests were performed using the pilot scale machine, C900. A 10 l stainless steel cylindrical vessel was used for the feed slurry. The vessel was equipped with a turbine impeller agitator to mix the sample with tap water. The tap water used in experiments was of 7.3 pH and 18-20 C temperature. 6000 cc of tap water was poured in the vessel and 2000 g of the dry sample was added for each MGS test. The water and the sample were agitated at a low agitation rate by the impeller for homogeneous slurry in the vessel. A sample bucket under the tailing discharge pipe and another bucket under the concentrate discharge pipe were placed for MGS. Feeding was carried out by a peristaltic pump at a flow rate of 2.3 l/min in MGS tests. 2000 g of the dry sample for MSG tests and 1000 g of dry sample for HIRMS were used for each test. A schematic form of the MGS experimental setup is given in Figure 1.
Samples from the chromite concentrate and tailing streams were collected at steady-state conditions. These samples were filtered, dried, and weighed for analysis of grade-recovery. For each sample, 0.2 g was dissolved in 15 ml of the mixture of sulfuric and phosphoric acids (2:1 ratio) and then heated at 300 C for 30 min. After dissolution, the solution was analyzed by the titrimetric method.
In order to produce a saleable chromite concentrate from the magnetic tailings of Guleman-Sori/Turkey, at first stage, MGS tests were carried out to produce pre-chromite concentrate and to determine optimum operating conditions of MGS. In this stage, five operating variables of MGS were drum speed, wash water, inclination in degrees, shake amplitude, and shake frequency. The feed pulp density of 25% solid by weight and the feed flow rate of 2.3 l/min were kept at constants for MGS tests. The experimental conditions of MGS and test results obtained are presented in Table 3.
In order to gain a better understanding the effect of each parameter of MGS on the grade and recovery, data in Table 3 are presented graphically in Figures 3-7. Figure 3 shows the effect of drum speed on concentrate grade and recovery. As can be seen, a higher concentrate recovery can be achieved at a drum speed of 200 rpm. Figure 4 shows the effect of wash water on concentrate grade and recovery. A higher concentrate grade and recovery can be achieved at wash water of 4 l/min. Figure 5 shows the effect of inclination on concentrate grade and recovery. It can be seen that a higher concentrate grade and recovery can be obtained with an inclination of 5. Figure 6 shows the effect of shake amplitude and Figure 7 shows the effect of shake frequency on concentrate grade and recovery, respectively.
Common practice in most mineral concentration plants is to maximize the operating profit by driving the process towards an optimum grade-recovery point on a more or less known concentrate grade recovery curve. To find out optimum operation parameters of the MGS, a grade-recovery curve was plotted from Table 3 data and the curve is shown in Figure 8. From Table 3 and Figure 8, it can be easily accepted that a pre-concentrate containing 32.6% Cr2O3 with 89.6% recovery is a reasonable result to produce a final concentrate. As shown in Table 3 and Figures 3-7, the optimum operation parameters are as follows: drum speed of 200 rpm, wash water 4 l/min, inclination of 5, shake amplitude of 15 mm, and shake frequency of 4 cps. Under these optimum conditions for producing pre-chromite concentrate, further MGS tests were performed 3 times under the same conditions. The mean results obtained are presented in Table 4. It can be seen from Table 4, the pre-chromite concentrate containing 32.6% Cr2O3 with 89.6% recovery could be produced at the optimum operation parameters determined.
The pre-concentrate consists of olivine, feldspar, and pyroxenes as gangue minerals. The pre-concentrate was screened to 75 m, and then the -300+75 m size fraction was fed into HIRMS to upgrade. On the other hand, the 75 m size fraction was considered as slime size.
At the second stage, some optimization tests were also conducted to determine the optimum operating parameters of the HIRMS, which were magnetic field intensity (0.6-0.9 T), roll speed (25-100 rpm), and rate of feeding material (250-1000 g/min), on the metallurgical performance of the HIRMS both by qualitative and quantitative means. Experimental conditions of the high-intensity induced-roll magnetic separator and results obtained are presented in Table 5.
In order to gain a better understanding of the effect of each parameter of HIRMS on the grade and recovery, data in Table 5 are presented graphically in Figures 9-11. Figure 9 shows the effect of magnetic field on concentrate grade and recovery. Figure 10 shows the effect of roll speed and Figure 11 shows the effect of feed rate on concentrate grade and recovery, respectively.
A grade-recovery curve for the final chromite concentration was also plotted from data in Table 5 and the curve is shown in Figure 12. In order to obtain the highest concentrate grade from the pre-chromite concentrate, as shown in Table 5 and in Figures 9-11, the optimum operation parameters of the HIRMS are as follows: magnetic field intensity of 0.8 T, roll speed of 50 rpm, and feed rate of 250 g/min. Under these operating conditions of the HIRMS, a final chromite concentrate containing 42.9% Cr2O3 could be obtained with 85.1% recovery.
The flow sheet for beneficiation of chromite tailings from the Guleman-Sori/Turkey chromite concentration plant by MGS + HIRMS is given in Figure 13. With the optimum operation parameters of MGS and HIRMS combined, results are presented Table 6.
To produce a pre-concentration of chromite tailings, the optimum operation parameters of MGS are as follows: drum speed of 200 rpm, wash water 4 l/min, inclination of 5, shake amplitude of 15 mm, and shake frequency of 4 cps. At these operation conditions, a pre-chromite concentrate containing 32.6% Cr2O3 with 89.6% recovery could be produced.
The optimum operating parameters of the HIRMS determined to produce final chromite concentrate from pre-concentrate are as follows: magnetic field intensity of 0.8 T, roll speed of 50 rpm, and feed rate of 250 g/min. At optimum conditions of the HIRMS, a final chromite concentrate containing 42.9% Cr2O3 with 85.1% recovery could be produced.
The results of beneficiation studies showed that MGS+HIRMS might upgrade this kind of tailing materials without further grinding. In this way, it is possible to reduce the amount of waste material by recovering its valuable content.
spiral (concentrators) - an overview | sciencedirect topics
The spiral concentrator is a modern high-capacity and low-cost device. It is developed for concentration of low-grade ores and industrial minerals in slurry form. It works on a combination of solid particle density and its hydrodynamic dragging properties. The spirals consist of a single or double helical conduit or sluice wrapped around a central collection column. The device has a wash water channel and a series of concentrate removal ports placed at regular intervals. Separation is achieved by stratification of material caused by a complex combined effect of centrifugal force, differential settling, and heavy particle migration through the bed to the inner part of the conduit (Fig.13.31). Extensive application is the treatment of heavy mineral beach sand consisting of monazite, ilmenite, rutile, zircon, garnet, and upgrade chromite concentrate. Two or more spirals are constructed around one central column to increase the amount of material that can be processed by a single integrated unit.
The spiral concentrator first appeared as a production unit in 1943 in the form of the Humphrey Spiral, for the separation of chrome-bearing sands in Oregon. By the 1950s, spirals were the standard primary wet gravity separation unit in the Australian mineral sands industry.
In the spiral concentrator the length of the sluicing surface required to bring about segregation of light from heavy minerals is compressed into a smaller floor space by taking a curved trough and forming into a spiral about a vertical axis. The slurry is fed into the trough at the top of the spiral and allowed to flow down under gravity. The spiralling flow of pulp down the unit introduces a mild centrifugal force to the particles and fluid. This creates a flow of pulp from the centre of the spiral outwards to the edge. The heaviest and coarsest particles remain near the centre on the flattest part of the cross-section, while the lightest and finest material is washed outwards and up the sides of the launder (Fig. 15.15). This separation may be assisted by the introduction of additional water flowing out from the centre of the spiral either continuously or at various locations down the length of the spiral. This wash water may be distributed through tubes or by deflection from a water channel that runs down the centre of the spiral. Some present designs have overcome the need for this wash water. Once the particle stream has separated into the various fractions, the heavy fraction can be separated by means of splitters at appropriate positions down the spiral. A concentrate, middlings mid tailing fraction can be recovered.
In practice spirals are arranged in stacks or modules of roughers, scavengers and cleaners, where the initial concentrate is retreated to upgrade the fraction to its final grade. Spiral length is usually five or more turns for roughing duty and three turns in some cleaning unite. For coal concentration, 6 turns providing a gentler slope with longer residence time for the more difficult separation.
The performance of spirals is dependent on a number of operating parameters, summarised in Table 15.9. Spirals generally a chieve an upgrade ratio of 3:1 (heavy fraction:feed grade) and hence multiply treatments are required . The presence of slimes adversely affects the spiral performance. More than 5% of 45m slimes will affect the separation efficiency.
With the steep pitch of a spiral, two or three spirals can be wound around the same common column and these types of spirals have been used in Australia for more than 20years. The multistart spirals conserve floor space and launder requirements. These triple-start spirals are built into a twelve spiral module and for these modules, the design of the distributor is critical to ensure that each spiral has a uniform feed.
The splitter blades on these spirals are all adjustable to direct the heavy fraction into pipes or a collecting launder. The current range of spirals available consist of a number of different profiles which have individual separation characteristics. The dimensions of some of the available spirals range from 270 406mm pitch, 590 700mm diameter and 2.1 2.4m high.
The advantages that modem spirals offer are simple construction requiring little maintenance, low capital cost and low operating cost - no reagents required, no dense media losses occur, low operating personnel required.
This is another variation of gravity separation, using density differences and centrifugal force; Figure 3.13. Originally known as Humphreys spiral (after the inventor) a wide range of devices are now available. A spiral concentrator consists of a helical conduit of semi-circular cross-section. Feed pulp of between 15 and 45 percent solids in the size range 3 mm to 75 m is introduced at the top of the spiral. As it flows downwards, the particles stratify due to the combined action of centrifugal force, the differential settling rates of the particles, and the effect of interstitial trickling through the flowing particle bed. The higher specific gravity particles are removed through the port located at the lowest point in the cross-section. Wash water added at the inner edge of the stream, flows outwardly across the concentrate band. Adjustable splitters control the width of the concentrate band removed at the ports. The grade of concentrate drawn from descending ports decreases progressively, with tailings discharged from the lower end of the spiral conduit.
Gravity concentration is a proven process for mineral beneficiation. The gravity concentration techniques are often considered where flotation practice is less efficient and operational costs are high due to extremely complicated physical, chemical and mechanical considerations. The gravity separations are simple and separate mineral particles of different specific gravity. This is carried out by their relative movements in response to gravity along with one or more forces adding resistance to motion offered by viscous media such as air or water. Particle motion in a fluid depends on specific gravity, size and shape of the moving material. The efficiency increases with coarser size to move sufficiently but becomes sensitive in presence of slimes. There are many types of gravity separators suitable for different situations. There are many devices for gravity concentration. The common methods are manual pans, jigs, pinched sluice and cones, spiral concentrator and shaking table to name a few.
Panning as a mineral or metal recovery technique was known to ancients since centuries past. Gold panning was popular and extensively practiced in California, Argentina, Australia, Brazil, Canada, South Africa and India during the nineteenth century. Panning is done by manual shaking of tray containing riverbed sand and gravels, alluvial deposits containing precious metals like gold, silver, tin, tungsten etc. The shaking of the tray separates sand, stones and fine-grained metals into different layers by differential gravity concentration (Fig. 12.28). The undesired materials are removed. This is primitive practice at low cost and generally in practice at small scale by the local tribal people.
Jigs are continuous pulsating gravity concentration devices. Jigging for concentrating minerals is based exclusively on differences in the density of the particles. The elementary jig (Fig. 12.29) is an open tank filled with water. A thick bed of coarse heavy particles (ragging) is placed on a perforated horizontal jig screen. The feed material is poured from the top. Water is pulsated up and down (the jigging action) by pneumatic or mechanical plunger. The feed moves across the jig bed. The heavier particles penetrate through the ragging and screen to settle down faster as concentrate. The concentrate is removed from the bottom of the device. Jigging action causes the lighter particles to be carried away by the cross flow supplemented by a large amount of water continuously supplied to the concentrate chamber. Jig efficiency improves with relatively coarse feed material having wide variation in specific gravity. Jigs are widely used as efficient and economic coal cleaning device.
Pinched sluice and cones is an inclined trough made of wood, aluminum, steel and fiberglass, 60-90cm long. The channel tapers from about 25cm in width at the feed end to 3cm at the discharge end. Feed consisting of 50-65% solids enters the sluice and stratifies as the particles flow through the sluice. The materials squeeze into the narrow discharge area. The piling causes the bed to dilate and allows heavy minerals to migrate and move along the bottom. The lighter particles are forced to the top. The resulting mineral strata are separated by a splitter at the discharge end (Fig. 12.30). Pinched sluices are simple and inexpensive device. It is mainly used for separation of heavy mineral sands. A large number of basic units and recirculation pumps are required for an industrial application. The system is improved by development and adoption of the Reichert cone. The complete device is comprised of several cones stacked vertically in circular frames and integrated.
Spiral concentrator is a modern high-capacity and a low-cost device. It is developed for concentration of LGOs and industrial minerals in slurry form. It works on a combination of the solid particle density and its hydrodynamic dragging properties. Spirals consist of a single or double helical conduit or sluice wrapped around a central collection column. It has a wash water channel and a series of concentrate removal ports placed at regular intervals along the spiral. Separation is achieved by stratification of material caused by a complex combined effect of centrifugal force, differential settling and heavy particle migration through the bed to the inner part of the conduit (Fig. 12.31). The most extensive application is treatment of heavy mineral beach sand consisting of monazite, ilmenite, rutile, zircon, garnet etc. It is widely used to upgrade chromite concentrate. Two or more spirals are constructed around one central column to increase the amount of material that can be processed by a single integrated unit.
Shaking table consists of a sloping deck with a rifled surface. A motor drives a small arm that shakes the table along its length, parallel to the rifle pattern. This longitudinal shaking motion drives at a slow forward stroke followed by rapid return strike. The rifles are arranged in such a manner that heavy material is trapped and conveyed parallel to the direction of the oscillation (Fig. 12.32). Water is added to the top of the table and perpendicular to the table motion. The heaviest and coarsest particles move to one end of the table. The lightest and finest particles tend to wash over the rifles and to the bottom edge. Intermediate points between these extremes provide recovery of the middling (intermediate size and density) particles.
Shaking tables find extensive use in concentrating gold. It is also used in the recovery of tin and tungsten minerals. These devices are often used downstream of other gravity concentration equipments such as spirals, Reicherts cone, jigs and centrifugal gravity concentrators for final cleaning prior to refining or sale of product.
Multi-gravity separator (MGS) is a new development in flowing film concentration expertise which utilizes combined effect of centrifugal force and shaking (Fig. 12.33). Centrifugal force enhances the gravitational force and obtains better metallurgical performance by recovering particles down to 1m in diameter. It would otherwise escape into tailing stream if other conventional wet gravity separators like jigs, spiral, table etc. are used. The principle of the system consists essentially in wrapping the horizontal concentrating surface of a conventional shaking table into a cylindrical drum and then rotates. A force, many times greater than the normal gravitational pull, is exerted by this means on particles in the film flowing across the surface. This enhances the separation process to a great extent. MGS in close circuit with lead rougher cells of graphite schist-hosted sulfide ore improves the lead concentrate metallurgy from 20 to +40% Pb. Graphitic carbon content reduces simultaneously from >10 to less than 3%. Presence of graphitic carbon interferes with the flotation of sulfide ore resulting in low metal recovery and unclean concentrate. MGS improves the metallurgical recovery and quality of concentrate for graphite carbon-bearing sulfide ore and high alumina-bearing fine iron ore. MGS technique is working successfully at Rajpura-Dariba zinc-lead plant and all iron ore plant in India by decreasing graphitic carbon and alumina respectively. MGS improves 42.9% Cr2O3 with 73.5% recovery from the magnetic tailings of Guleman-Sori beneficiation plant in Turkey.
The spiral concentrator applies differential density separation between particles to separate the valuable minerals from the gangue minerals. They have been widely utilized in coal washing plants worldwide to treat material in the particle size range 1mm150 m (other reports show that spirals are capable of treating material down to 45um). Material of such size range is too coarse to be treated using froth flotation and too fine to be treated in large diameter heavy medium cyclones (Atasoy and Spottiswood, 1995; Holland-Batt, 1995; Honaker etal., 2007; Mohanty etal., 2014; Shi etal., 2018). The major factors that makes this concentrator attractable for its application is low capital and operating cost, higher recoveries and no reagents used.
The drawback of spirals is that they are density separators that are unable to obtain a D50 lower than 1.65g/cm3 but tend to have a D50 between 1.7 and 2.1g/cm3 and misplaces a significant amount of ash fines into the clean coal. Even the application of wider diameter spirals couldnt solve this problem. The D50 was further reduced by either reducing the feed rate, but that is uneconomic or by utilizing two stage spirals in a series platform, but such a setup is still not sufficient to obtain a fine coal product of 10% ash value (Barry etal., 2015; de Korte, 2016; Shi etal., 2018; Ye etal., 2018). With the development of LC3 spiral model, lower separation cut point densities (1.41.55) were achieved (de Korte, 2016; Palmer, 2016). Palmer (2016) investigated the ash level in both the middling stream and clean coal product using LC3 spiral model and the results are shown in Fig.10. The results show that LC3 spiral model has high separation efficiency at both low and high D50.
Limited work has been done on the structural parameter of spirals and too much attention is given to the particle size distribution, feed rate, solid concentration and splitter position(Gulsoy and Kademli, 2006). Trough profile of the spirals is important factor to consider on separation performance of fine coal. Spirals come in three forms of trough profiles (ellipse, cubic parabola and synthetic curves) as illustrated in Fig.11 (Atasoy and Spottiswood, 1995; Kapur and Meloy, 1998; Kwon etal., 2017; Ye etal., 2018). It was observed that coal tends to move to the peripheral end of the spiral as the feed rate and solid concentration increases. The D50 also increases with feed rate and concentration of solids. Spiral concentrator with the elliptical profile is preferable to collect the light particles in outer place, while spiral concentrator with the trough profile of cubic parabola is effective for the accumulation of heavy particles in the inner region of the trough. The spiral concentrator with the trough profile of cubic parabola in inner place, together with the elliptical profile in outer place, is more desirable to separate the coal fines and ultrafines.
Run-of-mine (ROM) chromite (mined ore, prior to beneficiation) is usually beneficiated with relatively simple processes. The most commonly applied processes include primary and secondary crushing, screening, milling, dense media separation and gravity separation methods (Murthy etal., 2011). More sophisticated processes such as flotation can also be used (Wesseldijk etal., 1999), but are usually not economically feasible.
In order to generate beneficiated lumpy, chip and/or pebble chromite ore (the coarser fractions, typically 6150mm) crushing, screening and dense media separation would be applied. The finer fraction (typically<6mm) of ROM chromite would normally be milled to approximately<1mm and then upgraded with a series of hydrocyclones and spiral concentrators to generate metallurgical and/or chemical grade chromite concentrate (Murthy etal., 2011). Fig.5 presents a process flow diagram for the beneficiation of chromite concentrate (<1mm) adapted from Murthy etal. (2011), who reviewed chromite beneficiation. The shaking tables (slime and scavenger tables) in this diagram would probably not be used in large-scale operations and the single spiral concentrators would probably consist of numerous banks of spiral concentrators operating in parallel.
Milling is the only process step applied during chromite beneficiation that has been implicated in the possible generation of Cr(VI). However, only dry milling of chromite has been proven to generate Cr(VI) (Beukes and Guest, 2001; Glastonbury etal., 2010). Extreme grinding (i.e. pulverization), which is not a typical comminution technique, was applied in both the afore-mentioned referenced studies and it could therefore be argued that Cr(VI) is less likely to be formed by industrial dry milling. However, Beukes and Guest (2001) also report relatively high levels of Cr(VI) in samples gathered from a dry ball mill circuit at a FeCr producer. In contrast, wet milling does not seem to generate Cr(VI) (Beukes and Guest, 2001). Wet milling would also be the obvious choice during chromite concentrate beneficiation, since hydrocyclones and spiral concentrators are wet processes. Also, during chromite concentrate beneficiation the milling step would be aimed only at liberating the chromite crystals from the gangue minerals. This is in contrast to the dry milling tests conducted by Beukes and Guest (2001) and Glastonbury etal. (2010), during which Cr(VI) was generated, where the intent was to obtain particle sizes fine enough for pelletization (which will be discussed in Section 3.2.2 and 3.2.3).
Rare earth minerals are good candidates for gravity separation as they have relatively large specific gravities (47) and are typically associated with gangue material (primarily silicates) that is significantly less dense (Ferron et al., 1991). The most commonly utilized application of gravity separation is in monazite beneficiation from heavy mineral sands. Beach sand material is typically initially concentrated using a cone concentrator to produce a heavy mineral pre-concentrate (2030% heavy minerals) before a more selective gravity separation step, often employing a spiral concentrator, is used to achieve concentrations of 8090% heavy minerals (Gupta and Krishnamurthy, 1992). At this point, a series of magnetic, electrostatic and further gravity separation operations must be applied, according to each individual deposits mineralogy (Ferron et al., 1991).
An example of a flowsheet designed to concentrate monazite from Egyptian beach sands containing approximately 30wt.% valuable heavy minerals can be seen in Fig. 3 (Moustafa and Abdelfattah, 2010). In this flowsheet, low specific gravity gangue is discarded via wet gravity concentration (the authors employed a Wifley shaking table for this purpose), then low intensity magnetic separation is used to discard any ferromagnetic minerals without removing paramagnetic monazite (Moustafa and Abdelfattah, 2010). The non-magnetic stream that remains contains most of the valuable monazite, zircon and rutile as well as a portion of the gangue minerals which were not removed in the first two steps. A series of gravity, magnetic and electrostatic separations are then applied to exploit the different properties of the monazite, zircon and rutile minerals and produce the final concentrate streams. Rutile is removed as it reports to the conductor fraction after electrostatic separation (monazite and zircon are non-conductive) and then diamagnetic zircon may be removed from the paramagnetic monazite via further magnetic separation (Moustafa and Abdelfattah, 2010).
Fig. 3. Flowsheet for concentrating monazite from Egyptian beach sand. For each stream, the first and second percentages represent total weight recovery and monazite grade respectively. Reproduced with permission from (Moustafa and Abdelfattah, 2010).
In addition to the processing of beach sands, gravity separation, (shaking tables, spiral concentrators, and conical separators) is used in combination with froth flotation at many rare earth mineral processing operations throughout China (Chi et al., 2001). An example of this is at Bayan Obo, where gravity separation has been employed between the rougher and cleaner flotation circuits to efficiently separate monazite and bastnsite from the iron-bearing and silicate gangue material (Chi et al., 2001; Jiake and Xiangyong, 1984). Some challenges associated with gravity separation of the Bayan Obo ore are that gangue minerals (e.g. barite) have similar specific gravities to the desired rare earth minerals and report to the concentrate stream. In addition, gravity separation is ineffective at separating very fine particles resulting in large losses of rare earths (Ming, 1993). Some separation of very fine particles can be achieved for minerals with very large differences in specific gravity, such as gold from silicate gangue, by employing centrifugal gravity separators such as the Knelson, Falcon and Mozley Multi-Gravity Separators (Falconer, 2003; Gee et al., 2005). Most of these fine particle separators are designed for semi-continuous operation where the valuable dense material is present in low concentrations (<0.1wt.%) which may limit their suitability to REE mineral separation (Fullam and Grewal, 2001). The ongoing development of centrifugal separators capable of continuous operation (e.g. Knelson CVD) may address this issue as the manufacturers claim to be able to process feed materials with valuable heavy mineral contents of up to 50wt.% (Fullam and Grewal, 2001).
Outside of China, lab-scale gravity separations have been successfully completed on Turkish and Australian deposits with very fine-grained mineralizations (Guy et al., 2000; Ozbayoglu and Umit Atalay, 2000). In both of these cases, one of the key findings was that the rare-earth minerals were concentrated into the very fine (<5m) particle size range (Guy et al., 2000; Ozbayoglu and Umit Atalay, 2000). This was dealt with by either modifying the grinding steps to prevent excess fine generation or by employing a Multi-Gravity Separator, specifically designed to recover ultrafine particles via gravity separation (Guy et al., 2000; Ozbayoglu and Umit Atalay, 2000). The modified grinding procedure employed an attrition scrubbing step prior to further grinding to produce a product that was 100% 300m (the size which was identified as the maximum limit for downstream flotation), while reducing the slime losses to the 5m size fraction by an average of 7.8% (Guy et al., 2000). The results from Guy et al. (2000) can be seen in Fig. 4. The importance of adequately liberating rare earth minerals without excessive fine production has also been shown by Fangji and Xinglan (2003) who employed screening and secondary grinding steps after gravity and magnetic separations at a mine in Maoniuping, China to produce a bastnsite flotation concentrate with a grade of 62% REO and a recovery of 8085%.
A final interesting application of gravity separation to rare earth mineral concentration is the use of roasting operations prior to gravity separation as outlined in a 1956 patent (Kasey, 1956). The idea presented involved roasting a rare earth carbonate ore at temperatures in excess of 1000C to convert the carbonates into oxides, thereby increasing the mineral density and susceptibility to gravity separation (Kasey, 1956). The process proposed by Kasey (1956) included an industrial application involving quenching the roasted ore particles from high temperatures; a process that would likely significantly decrease the energy required for crushing and grinding operations as detailed by Fitzgibbon (1990) in their research into thermally assisted liberation. To the best of authors knowledge, this process was never successfully applied on an industrial or pilot scale.
most common used gravity concentrators - jxsc machine
Gravity concentration is a proven process for mineral beneficiation. The gravity concentration techniques are often considered where flotation practice is less efficient and operational costs are high due to extremely complicated physical, chemical and mechanical considerations.
The gravity separations are simple and separate mineral particles of different specific gravity. This is carried out by their relative movements in response to gravity along with one or more forces adding resistance to motion offered by viscous media such as air or water. Particle motion in a fluid depends on specific gravity, size and shape of the moving material.
The efficiency increases with coarser size to move sufficiently but becomes sensitive in presence of slimes. There are many types of gravity separators suitable for different situations. There are many devices for gravity concentration. The common methods are manual pans, jigs, pinched sluice and cones, spiral concentrator and shaking table to name a few.
Panning as a mineral or metal recovery technique was known to ancients since centuries past. Gold panning was popular and extensively practiced in California, Argentina, Australia, Brazil, Canada, South Africa and India during the nineteenth century.
Panning is done by manual shaking of a tray containing riverbed sand and gravels, alluvial deposits containing precious metals like gold, silver, tin, tungsten etc. The shaking of the tray separates sand, stones and fine-grained metals into different layers by differential gravity concentration. The undesired materials are removed. This is primitive practice at low cost and generally in practice at small scale by the local tribal people.
Jigs are continuous pulsating gravity concentration devices. Jigging for concentrating minerals is based exclusively on differences in the density of the particles. The elementary jig is an open tank filled with water. A thick bed of coarse heavy particles (ragging) is placed on a perforated horizontal jig screen.
The feed material is poured from the top. Water is pulsated up and down (the jigging action) by pneumatic or mechanical plunger. The feed moves across the jig bed. The heavier particles penetrate through the ragging and screen to settle down faster as concentrate. The concentrate is removed from the bottom of the device. Jigging action causes the lighter particles to be carried away by the cross flow supplemented by a large amount of water continuously supplied to the concentrate chamber.
Pinched sluice and cones is an inclined trough made of wood, aluminum, steel and fiberglass, 60-90 cm long. The channel tapers from about 25 cm in width at the feed end to 3 cm at the discharge end. Feed consisting of 50-65% solids enters the sluice and stratifies as the particles flow through the sluice.
The materials squeeze into the narrow discharge area. The piling causes the bed to dilate and allows heavy minerals to migrate and move along the bottom. The lighter particles are forced to the top. The resulting mineral strata are separated by a splitter at the discharge end. Pinched sluices are simple and inexpensive devices. It is mainly used for separation of heavy mineral sands. A large number of basic units and recirculation pumps are required for an industrial application.
Spiral concentrator is a modern high-capacity and a low cost device. It is developed for concentration of LGOs and industrial minerals in slurry form. It works on a combination of the solid particle density and its hydrodynamic dragging properties.
Spirals consist of a single or double helical conduit or sluice wrapped around a central collection column. It has a wash water channel and a series of concentrate removal ports placed at regular intervals along the spiral. Separation is achieved by stratification of material caused by a complex combined effect of centrifugal force, differential settling and heavy particle migration through the bed to the inner part of the conduit.
The most extensive application is treatment of heavy mineral beach sand consisting of monazite, ilmenite, rutile, zircon, garnet etc. It is widely used to upgrade chromite concentrate. Two or more spirals are constructed around one central column to increase the amount of material that can be processed by a single integrated unit.
This longitudinal shaking motion drives at a slow forward stroke followed by rapid return strike. The rifles are arranged in such a manner that heavy material is trapped and conveyed parallel to the direction of the oscillation. Water is added to the top of the table and perpendicular to the table motion. The heaviest and coarsest particles move to one end of the table. The lightest and finest particles tend to wash over the rifles and to the bottom edge. Intermediate points between these extremes provide recovery of the middling (intermediate size and density) particles.
Shaking tables find extensive use in concentrating gold. It is also used in the recovery of tin and tungsten minerals. These devices are often used downstream of other gravity concentration equipment such as spirals, Reicherts cones, jigs, and centrifugal gravity concentrators for final cleaning prior to refining or sale of the product.
Multi-gravity separator (MGS) is a new development in flowing film concentration expertise which utilizes the combined effect of centrifugal force and shaking. Centrifugal force enhances the gravitational force and obtains better metallurgical performance by recovering particles down to 1 mm in diameter. It would otherwise escape into the tailing stream if other conventional wet gravity separators like jigs, spiral, table etc. are used.
The principle of the system consists essentially in wrapping the horizontal concentrating surface of a conventional shaking table into a cylindrical drum and then rotates. A force, many times greater than the normal gravitational pull, is exerted by this means on particles in the film flowing across the surface. This enhances the separation process to a great extent. MGS in close circuit with lead rougher cells of graphite schist-hosted sulfide ore improves the lead concentrate metallurgy from 20 to 40% Pb. Graphitic carbon content reduces simultaneously from >10 to less than 3%. Presence of graphitic carbon interferes with the flotation of sulfide ore resulting in low metal recovery and unclean concentrate. MGS improves the metallurgical recovery and quality of concentrate for graphite carbon bearing sulfide ore and high alumina-bearing fine iron ore.
application of enhanced gravity separators for fine particle processing: an overview | springerlink
Beneficiation of low-grade ore is of critical importance in order to meet the growing demand for coal and mineral industries. But, low-grade ores require fine grinding to obtain the desired liberation of valuable minerals. As a result, production of fine particles makes the beneficiation process difficult through conventional gravity separators. Hence, alternative beneficiation techniques are being investigated for upgradation of metal values from low-grade ores. The gravitational force effecting the separation is replaced by the centrifugal force to usher in enhanced gravity separators. The objective of the present paper is to summarize the applicability aspect of enhanced gravity separators for different mineral systems including non-ferrous, precious, ferrous, and industrial minerals. These mineral systems include run off mine ore, secondary products like tailings and plant slags, etc. For this purpose, the design, operational features, types, and separation mechanism of enhanced gravity separators, such as Falcon concentrator, Knelson concentrator, multi-gravity separator (MGS), and Kelsey Jig, are discussed. Based on our review, research scope and future possibilities of enhanced gravity separators are also proposed.
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The authors would like to acknowledge Late Prof. Rayasam Venugopal for his suggestions to improve the manuscript in its initial stage. The corresponding author is thankful to the Director of CSIR-IMMT for his kind permission to publish this work.
Nayak, A., Jena, M.S. & Mandre, N.R. Application of Enhanced Gravity Separators for Fine Particle Processing: An Overview.
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spiral concentrator | multotec
As a turnkey supplier of gravity concentration equipment across the world, Multotec can deliver end-to-end spiral solutions, from process audits and test work, to complete spiral concentration plants optimised for your process. With our global branch network, we support your application with tailored field service and complete availability of spares for your plant.
Your local Multotec branch will help you with end-to-end solutions for your gravity concentration plant, from testing equipment through to field service, ongoing optimisation and any maintenance. We keep a wide range of spares and accessories for your spirals, reducing lead times to ensure maximum processing uptime.
We have a range of spirals, from 3 to 12 turns, with high-, medium- and low-gradient profiles. Our high capacity spirals (the HX series) provide a per-start tonnage rating of 4 to 7.5 tons per hour, depending on the mineral type, and is especially suited for the treatment of low-grade ore, where large tonnages are processed.
Mineral spiral separator components include the spiral trough; sliding or auxiliary splitters; launders; distributor and piping; feed box; product box and stainless steel product splitters; and the discharge chute at the bottom of the modular housing frame. Our spiral separators have a diameter of +/- 950 mm.
Our single- and double-stage spiral separators are optimised for coal particles in the size range of 1 to 0.1 mm, providing enhanced coal washing for slurries. Their compact, modular design provides flexibility when building or upgrading your plant.
Double start spirals reduce the requirements of height and floor space in a plant, and reduce capital and operating costs. The MX7 spiral separator is ideal for difficult-to-wash coals, improving the overall efficiency of tougher separation applications.
Spiral concentrators are simple low energy-consuming devices used for mineral separation mainly on the basis of density or by shape. 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 particles as they move down the trough of the spiral circuit. These forces include gravitational forces, centrifugal force, hydrodynamic drag, and lift and friction forces. Apart from the forces acting on a spiral, the properties of the slurry flowing on a spiral including, solids concentration, feed rate and wash water also plays an important role in the separation on the spiral.
During separation, the heavy particles migrate toward the inner region of the trough, with lighter-density particles migrating to the outer edge of the trough. In a dry spiral separation, materials are sorted by shape. Rounder particles travel faster, are forced to the perimeter of the spiral, from where they can be collected separately from non-round material.
spiral separators - mineral processing
FRP spiral chute combines the advantages of spiral concentrator, spiral chute, shaker, and centrifugal concentrator, and is the best equipment for mining and beneficiation, especially the sand mining in the seashore, riverside, sand beach and stream.
Spiral chute is used to select fine-grained iron, tin, tungsten, tantalum, niobium, gold ore, coal mine, monazite, rutile, zircon and other metal and non-metallic minerals with sufficient specific gravity difference. The sorting process is stable and easy to control, the allowable range of feed concentration is wide, the enrichment ratio is high and the recovery rate is high.
The spiral chute mainly uses the inertial centrifugal force generated by the minerals of different densities in the spiral rotation to achieve the separation of light and heavy minerals. Because of its simple equipment structure, low power consumption, and large processing capacity, it is widely used in the gravity separation process.
Chute beneficiation belongs to bevel flow separation process. The slurry is given to a certain inclined chute. Under the impetus of water flow, the ore particles are loose and layered. The upper layer of light minerals is quickly discharged from the tank, and the lower layer of heavy minerals is retained in the tank or discharged from the lower part at a low speed. After that, concentrate and tailings are obtained.
The spiral chute is composed of six parts: ore feed divider, ore feed groove, spiral groove, product intercepting groove, ore receiving hopper and groove bracket.The spiral groove composed of spiral pieces is the main component. The spiral pieces are made of glass steel (glass fiber reinforced plastic) and are connected together by bolts. The glass fiber reinforced plastic spiral sheet is light and strong, and has a wear-resistant layer on the surface, which is durable.
The first end of the trough is equipped with a multi-tube ore-feeding splitter, which is evenly distributed and easy to control. The evenly divided pulp is slowly fed to the spiral groove surface by feeding minerals.The end of the spiral groove is equipped with a valve block type product intercepting groove, which divides the sorted ore flow into several products according to grade. Use the position of the adjustment valve block to change the interception width of each product.The receiving hopper is a concentric ring cylinder, which collects and exports multiple intercepted streams according to products.
The spiral chute is based on the density difference between the minerals to achieve the purpose of sorting, and at the same time, it can recover the iron minerals that have been separated by monomers at a relatively coarse particle size level (generally not affected by the type and magnetic properties of iron minerals, surface) chemical properties etc.).Therefore, it can be widely used in various combined processes of processing magnetite (including roasted magnetite), hematite and other minerals such as weak magnetic-strong magnetic-flotation. It can supplement, assist, improve and improve processes such as magnetic separation, flotation, centrifuge reselection, and fine sieve.
The main advantages of the chute are the simple structure of the equipment, the low investment and production costs, and the coarse and medium-grain chute also have a high processing capacity. The disadvantage is that the separation accuracy is low, so it is suitable for use as a rough separation equipment. It is widely used in the treatment of tungsten, tin, gold, platinum, iron and some rare metal ores, especially in the treatment of low-grade sand ores. It has no moving parts and consumes no power; The equipment covers a small area and has a large processing capacity; Because the quality score of the ore is high and no washing water is added, water is saved; The conditions required for operation (such as ore feeding granularity, quality score, etc.) are not harsh, and the selection index is relatively stable. Light weight, moisture-proof, rust-proof, corrosion-resistant and noise-free.