China manufacturing industries are full of strong and consistent exporters. We are here to bring together China factories that supply manufacturing systems and machinery that are used by processing industries including but not limited to: wet magnetic separator, magnetic separator, mining equipment. Here we are going to show you some of the process equipments for sale that featured by our reliable suppliers and manufacturers, such as Ilmenite Ore Separator Machine. We will do everything we can just to keep every buyer updated with this highly competitive industry & factory and its latest trends. Whether you are for group or individual sourcing, we will provide you with the latest technology and the comprehensive data of Chinese suppliers like Ilmenite Ore Separator Machine factory list to enhance your sourcing performance in the business line of manufacturing & processing machinery.
Ilmenite is one of the most important ores of the metal titanium in the world. It is mined as an important industrial mineral in several deposits throughout the world, and many of them are in placer sands. Ilmenite is very similar in structure to Hematite, and is essentially the same as Hematite with roughly half the iron replaced with titanium. Ilmenite is a weakly magnetic titanium-iron oxide mineral which is iron-black or steel-gray. Most ilmenite is mined for titanium dioxide production.Ilmenite is a titanium bearing mineral that, directly or indirectly, supplies in excess of 90% of the feedstock to the large titanium dioxide pigment industry as well as to the very significant and growing titanium metal market and some smaller industrial applications.
In the ilmenite raw ore crushing process, we need to use the crusher. Shanghai shibang company can provide different types of crusher for choosing which refers to the crushing machine used for dealing with large ilmenite stones. Like jaw crusher, impact crusher and cone crusher. You can choose one or two crushers to compose of your ilmenite mining production line.
PE series jaw crusher is usually used as primary crusher in quarry production lines, mineral ore crushing plants and powder making plants. It manufactured with world-class manufacturing technology and advanced digital parts processing equipment to ensure the precision of the machine parts. Choosing the best production material, greatly enhance the compressive resistance, wear resistance and greatly prolong the service life of the machine.
PF series impact crusher can be used to deal with materials whose size below 500mm and whose compression strength less than 360Mpa. It has high grinding efficiency, the rotational inertia of the rotor has a large and low energy consumption; The top of the machine is equipped with discharging mouth adjusting device which can be simple and quick adjustment counterattack plate and plate hammer gap and control the size of discharge; Product shape is a cube, no tension fracture. Grain shape is good. According to the standard of all kinds of sand and gravel aggregate level, it is suitable. Also it has simple structure and convenient in maintenance.
Apart from crushing equipment, we also need conveyorbeltinilmenitemining processing which will be used in composing of conveying system. Conveyor belt for ilmenite mining is available with either rollersor a solid surface to support the carrying belt. When ilmenite stones fall down on the conveyor, the roller under the belt will drive the belt come forward. In this way, conveyor belt can transfer materials continuously and evenly.
Most ilmenite ore are poor ilmenite ore, so the ore processing must be carried out. Ilmenite ore beneficiation methods currently used for the mechanical selection (including washing, screening, re-election, high intensity magnetic separation and flotation), as well as fire enrichment, chemical processing method. During the whole production line, electric separation, gravity separation and strong magnetic separation, flotation separation and roasting separation are all the necessary steps.
The ilmenite mining process includes gravity separation, magnetic separation and electric separation. Firstly, the raw materials should be extracted from the mine. After this step, the concentrated mines which contain the gravity materials will get. You can get the ilmenite with the help of middle strong magnetic separation. The strong magnetic will recover the monazite and the shaking table is used to remove the gangue. The electric separation is mainly used for separating the rutile with zircon.
China manufacturing industries are full of strong and consistent exporters. We are here to bring together China factories that supply manufacturing systems and machinery that are used by processing industries including but not limited to: mining machine, mining machinery, gold mining equipment. Here we are going to show you some of the process equipments for sale that featured by our reliable suppliers and manufacturers, such as mining equipment. We will do everything we can just to keep every buyer updated with this highly competitive industry & factory and its latest trends. Whether you are for group or individual sourcing, we will provide you with the latest technology and the comprehensive data of Chinese suppliers like mining equipment factory list to enhance your sourcing performance in the business line of manufacturing & processing machinery.
Ilmenite has a specific gravity of up to 5.1. Saasen et al. (2001) reported a higher drilling penetration rate from the use of ilmenite, because a lesser colloidal solids fraction was produced during drilling. Ilmenite was used in drilling operations in the North Sea in 1979 and 1980. The ilmenite was a fairly coarse ground material compared to the presently used ilmenite. The drilling fluid properties were easier to control compared to drilling with barite. Again, this was because ilmenite has a lower tendency of being ground down to finer particles. Environmental aspects suggest replacing barite with ilmenite. However, the use of ilmenite as a weighting material can cause severe abrasion problems. Using ilmenite with a narrow particle size distribution around 10 can reduce the erosion to a level experienced with barite (Saasen et al., 2001).
Ilmenite is not a common mineral in soils; when it is found it is usually inherited from igneous or metamorphic parent rocks. Although the positions of the oxygen atoms and the cations in ilmenite are almost identical to those in hematite, the iron in ilmenite is almost entirely divalent and the titanium quadrivalent. Although considerable substitution of Mg2+ and Mn2+ for Fe2+ can occur, normally only small amounts of these elements are found.
The atomic coordinates of the oxygen and metal ions in ilmenite are almost identical to those of hematite. The iron and titanium atoms are distorted in an ordered way on the cation sites. Between one pair of planes of oxygen atom all the cations of Fe2+ and between the next pair all the cations are Ti4+ and thus an alternating sequence is followed through the structure.
Ilmenite is also present in sand deposits: coastal or alluvial placers. Such deposits are found on the coasts of Australia, Africa, the United States, India, Vietnam, China, Ukraine, and elsewhere [2,3]. Beach sand ilmenites are different from rock ilmenites in their morphology and composition. Sand ilmenite grains have a characteristic round appearance due to erosion (Fig.3.5), and their TiO2 content is usually higher than 50% wt. because of natural oxidation and leaching of iron (weathering). Some sand ilmenite concentrates, like that produced by QMM in Madagascar, contain as much as 60% wt. TiO2 .
Coastal and alluvial placers may contain a small percentage of ilmenite, rutile, and other heavy minerals (e.g., about 2%5% wt.), but they are relatively easy to exploit. In sand mining operations, the ore is recovered by floating dredges (wet mining) or by bulldozers and scrappers (dry mining). As shown in Fig.3.6, the sand is usually fed to a wet concentrator or primary concentrator to produce heavy minerals concentrate (HMC), which is a mixture of ilmenite, rutile, magnetite, zircon (ZrSiO4), and other high-density minerals. The wet HMC is fed to the LIMS to sort out the highly magnetic magnetite. The LIMS tailings are then sent to the HIMS to recover ilmenite. The nonmagnetic fraction of HIMS is dried and sent to high-tension electrostatic separation in order to split nonconductor zircon from conductor rutile. Depending on the exact composition of HMC, the dry mineral processing plant may include separation of other mineral products like leucoxene (weathered high-TiO2 ilmenite) and monazite (phosphate mineral of rare earths and thorium). The tails are often treated to reclaim residual ilmenite, rutile, and zircon.
Figure3.6. Simplified generic block flow diagram of a sand mining operation, Highly altered ilmenites with 60% TiO2 or more may have a somehow different processing route. Also the nomenclature of the processing steps (wet separation plant, etc.) differs from one operation to another.
Leucoxene is not a mineral species as such. It is a fine, granular, and high alteration product of ilmenite, which after extensive natural weathering has lost much of its iron content. As a result, leucoxene is a microassembly of titanium-rich titanate minerals like rutile (TiO2), pseudorutile (Fe2Ti3O9), etc. . It may contain anywhere between 70% and 90% wt. TiO2. Depending on the complexity and cost of separation, few sand mines produce leucoxene concentrates, while others prefer to leave it together with ilmenite, and thus increase the TiO2 content of the ilmenite concentrate.
Rutile is tetragonal titanium dioxide (TiO2). It is the most common and most thermodynamically stable of four TiO2 polymorphsthe other three being the more scarce anatase (also tetragonal) and brookite (orthorhombic), and the extremely rare akaogiite (monoclinic). Presently, almost all commercially available rutile originates as coproduct of sand mining operations. Only in Sierra Leone, there are sand deposits exploited essentially for rutile [2,3]. Finely dissipated rutile is found in alterations of igneous rock formations, like in the diorites-granodiorites of Cerro Blanco, Chile. Anatase deposits have also been discovered in the Brazilian states of Minas Gerais (Tapira, Salitre) and Gois (Catalo) . Those fine-grained deposits contain high levels of radionuclides andapparently for these reasonsthey have not been commercially exploited.
Like rock ilmenite, sand ilmenite can be smelted for the production of titania slag. Sand ilmenite containing anywhere between 45% and 55% wt. TiO2 is also common feedstock for the production of TiO2 pigment by the Sulfate process. When its TiO2 grade exceeds 58% wt., sand ilmenite can be converted to synthetic rutile via the Becher and the Benelite processes. Chemours in the United States and Mexico is probably the only company that takes sand ilmenite containing about 60% wt. TiO2 and converts it directly (but usually in mixtures with leucoxene, natural rutile, synthetic rutile and slags) into TiCl4, and ultimately into TiO2 pigment via the so-called Chloride process.
Leucoxene concentrates are usually sold for the production of TiO2 pigment by the Chloride process. Natural rutile concentrates, which typically contain 92%96% wt. TiO2, can be used for either the production of TiO2 pigment or the production of raw titanium metal. In the case of TiO2 pigment production, rutile concentrate is first chlorinated to TiCl4, and then TiCl4 is purified and oxidized again to ultrafine pure TiO2 (see Chapter 4). In the case of raw titanium metal production, purified TiCl4 is reduced by magnesium or sodium metal. The only drawback of nature rutile is that its supply is rather limited, and hence TiO2 chloride pigment producers and titanium metal producers have to complement their feeds with high-grade titania slags, synthetic rutile, and UGS (upgraded titania slag).
Mineral sands contain zircon, ilmenite, and rutile, with xenotime and monazite. These minerals are mined in many countries and production amounts to millions of tons per year of zirconium and titanium (from rutile and ilmenite), though thorium, tin, and the rare earth elements are associated. The NORM aspect is due to monazitea rare earth phosphate containing a variety of rare earth minerals (particularly cerium and lanthanum) and 5%12% (typically about 7%) thorium, and xenotimeyttrium phosphate with traces of uranium and thorium.
The minerals in the sands are subject to gravity concentration, and some concentrates are significantly radioactive, up to 4000Bq/kg. Most of this NORM ends up in the waste streams from mineral processing (often including monazite) and so, apart from zircon, the final product is itself devoid of NORM. However, sometimes niobium and tantalum are recovered from the waste stream, and residues may be used as either landfill or in construction sites where there is a possibility of public exposure. Table 2.7
Over 95% of the market for zirconium requires it in the form of zircon (zirconium silicate). This mineral occurs naturally and is mined, requiring little processing. It is used chiefly in foundries, refractories manufacture, and the ceramics industry. Zircons typically have activities of up to 10,000Bq/kg of U-238 and Th-232. No attempt is usually made to remove radionuclides from the zircon as this is not economical. Because zircon is used directly in the manufacture of refractory materials and glazes, the products will contain similar amounts of radioactivity. Higher concentrations may be found in zirconia (zirconium oxide), which is produced by high-temperature fusion of zircon to separate the silica. Zirconium metal manufacture involves a chlorination process to convert the oxide to zirconium chloride, which is then reduced to the metal.
During mining and milling of zircon, care must be taken to keep dust levels down. Then when zircon is fused in refractories or ceramics manufacture, silica dust and fumes must be collected. This may contain the more volatile radionuclides, Pb-210 andPo-210, and the collection of these gases means that pipeworks and filters become contaminated. The main radiological issue is occupational exposure to these radionuclides in airborne dusts in the processing plant. Waste produced during zirconia/zirconium production can be high in Ra-226, which presents a gamma hazard, and waste must be stored in metal containers in special repositories. Powders from filters used during zirconia manufacture have been assayed as high as 200,000Bq/kg of Pb-210 and 600,000Bq/kg Po-210.
Ilmenite is a combined oxide naturally occurring in the form FeTiO3, which is also the reduced form in CLC. The oxidized form is Fe2TiO5+TiO2. It has also been shown that there is a migration of Fe to the surface; thus in practice ilmenite is in part an iron oxide material (Adanez etal., 2010).
A significant number of studies have used ilmenite, mostly Norwegian ilmenite. However, there are several possible sources for ilmenite. The important advantage of ilmenite is the low price in combination with having a reasonably high reactivity towards syngas and showing good fluidization behaviour. Estimations of the lifetime of ilmenite are around 700h, although no real long-term operation has been accomplished. It would be relevant to say that ilmenite at present represents state of the art for solid fuels.
A 100-kW unit for solid fuels at Chalmers (Linderholm, Schmitz, Knutsson, Klln, & Lyngfelt, 2014; Markstrm, Linderholm, & Lyngfelt, 2012; Markstrm, Lyngfelt, & Linderholm, 2012; Markstrm, Linderholm, & Lyngfelt, 2013a,b)
The titanium ore mineral is either rutile beach sands or ilmenite rock ores, or mineral sands whose composition is not primarily rutile such as monazite These mineral sands are not pure, since minerals such as monazite, ilmenite, zircon and others can be present. In a mineral sands mine most of these other minerals are separated by use of gravity and electrostatic separation methods to produce a higher-grade mineral sand. Typical analysis of mineral sands for TiCl4 production is shown below. Grades near 98% rutile can be produced by these methods.
Ilmenite, FeTiO3 is used in the manufacture of TiCl4, and subsequent production of TiO2, mostly for pigment applications. This mineral is mined as mineral sands or hard rock deposits. To separate the iron from the titanium compound strong hydrochloric acid is used, generating iron chloride solutions. The formation of the titanium salts is then converted to synthetic rutile (this can also create from some iron-making slags) and the synthetic rutile is then carbon chlorinated to anhydrous TiCl4, which is then condensed and purified.
The DuPont Chloride [7,8] - Ilmenite process used a reducing atmosphere with chlorine to remove the iron content of the ilmenite, then the operating point is adjusted to chlorinate the balance of the mineral to TiCl4. The carbochlorination reaction does not require that carbon be in direct contact with the ore . Chlorine converts the iron oxide directly to iron chloride. Chlorine and carbon then can convert the TiO2 to TiCl4. The resources of ilmenite globally are much higher than that of rutile sands, as result the cost of the raw material is much lower. The thermodynamics of the process show that the iron oxide phase can be selectively chlorinated with partial pressure of oxygen of 10-10 and chlorine partial pressures near 1atm .
There are other processes used to produce TiO2 pigment that do not require carbo-chlorination. Rutile and ilmenite can be leached with strong sulfuric acid to produce a titanium sulfate solution. This then can be induced to precipitate TiO2 as fine particles. Known as the sulfate process this was first developed in the production of pigment for paints. This method is not used for TiCl4 production for titanium metal production.
The Lurgi process  was developed to produce a synthetic rutile by reducing the iron content to metal that then can be separated by mineral processing methods. The Lurgi process operated at lower temperatures than the QIT process where a titania slag (sometimes called Sorelslag) is produced. This slag is crushed to liberation of the iron, this then can be separated by magnetic separation. The Australian firm Iluka developed and practices this method  the low temperature Lurgi process. Direct electrolysis of the titania slag to produce titanium have been reported by QIT .
The threefold nature of titanium production: TiCl4 production, Ti sponge production, magnesium chloride electrolysis can result in processes that are separated geographically. TiCl4 production can take place in a pigment-making facility, and the high grade TiCl4 sent to the sponge plant for reduction with magnesium. Since the TiCl4 can be produced elsewhere, only the final production composition of the TiCl4 is important. The production method or source of ore is not important provided the TiCl4 can be purified to meet the needs of the sponge production process. Separation of the magnesium production and TiCl4 production means that these two processes do not necessarily have to be in balance as chlorine can be compressed and sold as at US Magnesium .
Rutile ore with a TiO2 content of about 95%, upgraded ilmenite (UGI), or upgraded Ti slag (UGS) is used as feed material for the production of Ti metal. UGI (or UGS) is a chemically processed ilmenite ore with an upgraded TiO2 content compared with its naturally occurring value of 50%. Rutile or UGI (or UGS) powder is injected into a fluidized bed furnace, where it reacts with coke and Cl2 at about 1273K (Fig.5.3 [10,11]). Crude TiCl4 is synthesized by the following carbochlorination reaction:
In this process, impurities in TiCl4, such as FeClx, and AlCl3 with boiling points that differ considerably from that of TiCl4 (409K) are condensed and removed (Fig.5.4 ). On the contrary, impurities with boiling points similar to that of TiCl4, such as VOCl3, SnCl4, and SiCl4, remain in the processed TiCl4 intermediate feed material. By adding a reducing agent such as hydrogen sulfide (H2S), VOCl3 is removed through conversion into vanadium tetrachloride (VCl4), which has a higher boiling point than that of VOCl3. SnCl4 and SiCl4 are removed through a multistage distillation process. Highly pure (99.98%) TiCl4 is finally produced by this chloride distillation.
In 1791, William Gregor, a Cornish amateur chemist, used a magnet to extract the ore that we now know as ilmenite from a local river. He then extracted the iron from this black powder with hydrochloric acid, and was left with a residue that was the impure oxide of titanium. After 1932, a process developed by William Kroll permitted the commercial extraction of titanium from mineral sources. At the end of World War II, titanium metallurgy methods and titanium materials made their way from military application to peacetime uses. By 1940, satisfactory results had already been achieved with titanium implants (Bothe et al., 1940). The major breakthrough in the use of titanium for bony tissue implants was the Brnemark discovery of osseointegration, described above in the section on dental implants.
Sulfate/sulfuric acid leaching is often utilized on raw materials that contain high levels of iron such as commonly occur in typical ilmenite-based feedstock, which are generally a mixture of titanium dioxide, ferrous and ferric oxides, and a variety of other impurities such as chromium, vanadium, manganese, calcium, magnesium, aluminum, and silicon . The general reaction for sulfuric acid leaching of ilmenite, which must generally be ground to a fine powder in order for it to react at a reasonable rate, is:
The resulting solution of titanium oxide and ferrous sulfate is treated through the addition of a reducing agent such as metallic iron to convert all ferric ions to ferric ion to ferrous ions as shown in the reaction:
The solids are allowed to settle, and the liquid portion decanted, then the solution is concentrated by evaporation, and then chilled under vacuum to precipitate ferrous iron as light green by-product ferrous sulfate heptahydrate. The removal of iron is critical to the final color of the titanium dioxide, which is otherwise tainted by residual dissolved that remains in the final TiO2 product. The solution is then heated to 94110C and diluted with water to form hydrated titanium dioxide TiO2nH2O or TiO(OH)2. Seed crystals of TiO2 are often added as nuclei for precipitate formation, and the concentration of titanium sulfate in the solution is adjusted to 170230g/L by vacuum evaporation if needed . Nuclei are added to facilitate precipitation. The nuclei are usually produced in a separate reactor, often by boiling a small portion of the solution or adding sodium hydroxide at 100C to a small portion of the solution before feeding it into the bulk precipitation vessel . The hydration reaction can be written as:
In order to produce higher quality pigment, the resulting hydrated titanium dioxide product is often reslurried in dilute sulfuric acid (3%10%) at 5090C with a reducing powder such as zinc or aluminum in a process referred to as bleaching . Alternative chemicals can be used to perform bleaching. The final hydrated titanium dioxide is then calcined in a calciner (rotating tube furnace) to remove the water of hydration at temperatures over 1000K:
The high-temperature exposure also removes other volatile components and residual sulfuric acid, which is often chemically bound to the precipitate. In order to produce some pigment grades, mineralizers such as phosphoric acid are added prior to calcination. The calcined product generally needs some size reduction to achieve desired size distributions for further processing. In some cases, additives such as silica or aluminum oxide are blended with the titanium dioxide to facilitate subsequent mixing and processing .
Spiral concentrators have found many varied applications in mineral processing, but perhaps their most extensive application has been in the treatment of heavy mineral sand deposits, such as those carrying ilmenite, rutile, zircon, and monazite, and in recent years in the recovery of fine coal.
The Humphreys spiral was introduced in 1943, its first commercial use being on chrome-bearing sands. It is composed of a helical conduit of modified semicircular cross section. Feed pulp of between 15% and 45% solids by weight and in the size range from 3mm to 75m is introduced at the top of the spiral. As it flows spirally downward, the particles stratify due to the combined effect of centrifugal force, the differential settling rates of the particles, and the effect of interstitial trickling through the flowing particle bed. The result of this action is depicted in Figure 10.18. Figure 10.19 shows the stratification across a spiral trough, with the darker heavy mineral toward the center, with the band becoming increasingly lighter radially where the less dense material flows.
These mechanisms are complex, being much influenced by the slurry density and particle size. Mills (1980) reported that the main separation effect is due to hindered settling, with the largest, densest particles reporting preferentially to the band that forms along the inner edge of the stream. Bonsu (1983), however, reported that the net effect is reverse classification, the smaller, denser particles preferentially entering this band.
Determination of size-by-size recovery curves of spiral concentrators has shown that both fine and coarse dense particles are lost to the light product, the loss of coarse particles being attributed to the Bagnold force (Bazin et al., 2014). Some of the complexities of the spiral concentrator operation arise from the fact that there is not one flow pattern, but rather two: a primary flow down the spiral and a secondary flow across the trough flowing outward at the top of the stream and inward at the bottom (Figure 10.20) (Holland-Batt and Holtham, 1991).
Ports for the removal of the higher specific gravity particles are located at the lowest points in the cross section. Wash water is added at the inner edge of the stream and flows outwardly across the concentrate band to aid in flushing out entrapped light particles. Adjustable splitters control the width of the heavy product band removed at the ports. The heavy product taken via descending ports is of a progressively decreasing grade, with the light product discharged from the lower end of the spiral. Splitters at the end of the spiral are often used to give three products: heavies, lights, and middlings, giving possibilities for recycle and retreatment in other spirals (e.g., rougher-cleaner spiral combination) or to feed other separation units. Incorporating automatic control of splitter position is being developed (Zhang et al., 2012).
Until the last 20 years or so, all spirals were quite similar, based on the original Humphreys design. Today there is a wide range of designs available. Two developments have been spirals with only one heavy product take-off port at the bottom of the spiral, and the elimination of wash water. Wash waterless-spirals reportedly offer lower cost, easier operation, and simplified maintenance, and have been installed at several gold and tin processing plants.
Another development, double-start spiral concentrators with two spirals integrated around a common column, have effectively doubled the capacity per unit of floor space (Figure 10.21). At Mount Wright in Canada, 4,300 double-start spirals have been used to upgrade specular hematite ore at 6,900th1 at 86% recovery (Hyma and Meech, 1989). Figure 10.22 shows an installation of double-start spirals.
One of the most important developments in fine coal washing was the introduction in the 1980s of spiral separators specifically designed for coal. It is common practice to separate coal down to 0.5mm using dense medium cyclones (Chapter 11), and below this by froth flotation. Spiral circuits have been installed to process the size range that is least effectively treated by these two methods, typically 0.12mm (Honaker et al., 2008).
A notable innovation in fine coal processing is the incorporation of multistage separators and circuitry, specifically recycling middling streams (Luttrell, 2014). Both theoretical and field studies have shown that single-stage spirals have relatively poor separation efficiencies, as a compromise has to be made to either discard middlings and sacrifice coal yield or accept some middlings and a lower quality coal product. To address this, two-stage compound spirals have been designed in which clean coal and middlings are retreated in a second stage of spirals and the middlings from this spiral are recycled to the first spiral. This is essentially a rougher-cleaner closed-circuit configuration and it can be shown that his will give a higher separation efficiency than a single-stage separator (Section 10.8). The separation efficiencies achievable rival those of dense medium separators.
Some of the developments in spiral technology are the result of modeling efforts. Davies et al. (1991) reviewed the development of spiral models and described the mechanism of separation and the effects of operating parameters. A semi-empirical mathematical model of the spiral has been developed by Holland-Batt (1989). Holland-Batt (1995) discussed design aspects, such as the pitch of the trough and the trough shape. A detailed CFD model of fluid flow in a spiral has been developed and validated by Matthews et al. (1998). In Chapter 17, an example of particle tracking along a spiral used to verify model predictions is illustrated.
Spirals are made with slopes of varying steepness, the angle depending on the specific gravity of separation. Shallow angles are used, for example, to separate coal from shale, while steeper angles are used for heavy mineralquartz separations. The steepest angles are used to separate heavy minerals from heavy waste minerals, for example, zircon (s.g. 4.7) from kyanite and staurolite (s.g. 3.6). Capacity ranges from 1 to 3th1 on low slope spirals to about double this for the steeper units. Spiral length is usually five or more turns for roughing duty and three turns in some cleaning units. Because treatment by spiral separators involves a multiplicity of units, the separation efficiency is very sensitive to the pulp distribution system employed. Lack of uniformity in feeding results in substantial falls in operating efficiency and can lead to severe losses in recovery. This is especially true with coal spirals (Holland-Batt, 1994).