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importance of attrition scrubbing in flotation

Talc has found a steadily increasing number of uses such as cosmetics, steatite and cordierite ceramics, for pitch control in the paper industry and as a reinforcing filler in rubber, etc. In this research, the amenability of some Egyptian carboniferous finely disseminated talc ores to beneficiation by flotation was investigated on laboratory scale. The original talc sample is characterized by low MgO content (25.40%), low SiO2 (45.71%), high CaO content (6.32%) and high L.O.I. (11.35%), indicating its low grade. Attrition scrubbing of the crushed ores was found to be an unconventional process, not only for fine talc production, but also for proper separation of the harder carbonaceous gangue. Talc pre-concentrates, less than 0.074 μm, were prepared by attrition scrubbing in the laboratory having 8.40% L.O.I. with a yield reaching 74.70%. Cleaner talc concentrate with L.O.I. content averaging 6.70% was obtained by flotation in the presence of Aerofroth 71 with a yield reaching 64.71%. This was relatively improved by the use of a selective (quaternary amine) talc collector and in presence of a selective carbonate depressant (soda ash). Flotation of the fine ground talc (less than 22 μm) produced a talc concentrate assaying 6.90% L.O.I. with a yield recovery of 62.91%. However, different talc concentrates obtained by just natural floatability or by the use of small dose of Aerofroth 71, or by the application of quaternary amine in presence of carbonate depressant, satisfy the requirement of paper coating, ceramics production, functional filler, and pharmaceuticals applications. Tailings could also be used in carpets, roofs, and tiles production industries

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the art of talcflotationfor different industrial

The basic concept of native floatability of a mineral is that a naturally hydrophobic surface results when cleavage or fracture occurs between crystal layers which are held together by weak residual bonds―van der Waals forces. It is recognized that the crystalline structure is one of the main factors that determines the wettability of layered silicate minerals such as talc. Talc is a hydrous magnesium silicate, Mg3Si4O10(OH)2 , which is related to the sheet structure of the phyllosilicate (Yehia and Al Wakeel, 2000 [1] ). However, natural floatability of talc is closely related to its three-layer sheet crystal structure (Fuerstenau et al., 2003 [2] and Fuerstenau et al., 2007 [3] ). Positive charge of magnesium layer is compensated from two sides by silicon tetrahedral layers creating the lack of surface polarization responsible for its natural hydrophobicity

Talc is considered as anisotropic mineral, which when broken, two types of surfaces are formed, one resulting from the easily broken layers and the other resulting from the rupture of ionic bonds within these layers (Ivan et al., 2013 [4] ). The former are termed as “faces”, holding together by weak van der Waals forces, which are hydrophobic and consist of inert −Si−O−Si− groups. The latter are termed as “edges”, which are hydrophilic, consisting of SiOH and MgOH groups, and are held together by ionic bond. However, the edges which are created by rupturing of the covalent bonds are spontaneously reacting with water to form oxidic sites, for example, SiO− that is hydrophilic. On the other hand, the rupture of talc crystals along the faces generates non-polar surfaces, which are characterized by a low energy (El-Midany and Ibrahim, 2010 [5] ; Mierczynska and Beattie, 2013 [6] ). This allows talc to exhibit an inherent hydrophobicity, which is the basis of the separation of talc, by flotation, from other ore constituents in mineral industry. However, the heterogeneous character of talc surface particles has a particular importance in flotation. The face/edge relationship, which depends on the particle size, determines the natural floatability of this mineral (Mierczynska and Beattie, 2013 [6] ). Besides, the solution pH affects the talc floatability. In acidic and alkaline solution, water molecules would hydrate the negatively charged sites (SiO−) on the edges and hence, the talc surface would be more hydrophilic (Yehia and Al Wakeel, 2000 [1] ). At neutral pH, talc surface has a weak affinity for water molecules and air bubbles readily displace any weakly adsorbed water on the uncharged surface

The size of an individual talc platelet (a few thousand elementary sheets) can vary from approximately 1 micron to over 100 microns depending on the conditions of formation of the deposit. It is this individual platelet size that determines a talc’s lamellarity. A highly lamellar talc will have large individual platelets whereas a microcrystalline talc will have small platelets. The elementary sheets are stacked on top of one another, like flaky pastry, and because the binding forces (Van der Waal’s forces) linking one elementary sheet to its neighbors are very weak, the platelets slide apart at the slightest touch, giving talc its characteristic softness

the art of talcflotationfor different industrial

Different methods and approaches were investigated by researchers worldwide for the processing of talc- carbonate ores with different proportions of talc, magnesite and dolomite (Houot et al., 1995 [7] ; Marabini et al., 1996 [8] ; Weber, 1998 [9] ; Karlsen et al., 2000 [10] ; Derco and Memeth, 2002 [11] ; Ahmed et al., 2011 [12] ), and CANMET of Canada carried out an intensive R & D work on so many talc and pyrophyllite varieties by applying a wide array of frothers and collectors (Andrews, 1994 [13] ; Wyman, 1973 [14] )

Talc occurs in the form of veins or lenses in many localities in South and Central Eastern Desert of Egypt (EGSMA, 1991; MQA, 2004). Generally, talc is obtained by either open pit or underground mining. The cost of overburden removal in open pit mining is a major factor in talc mining and waste rock to ore ratios of 40:1 are not uncommon. Processing of low grade varieties is becoming unequivocal and few studies are carried out, on a laboratory scale, to separate both carbonate and iron oxide gangue minerals (Yousef et al., 1995 [15] ; El-Wakeel, 1996 [16] ; Ibrahim, 2003 [17] ; Selim, A.Q., Ibrahim, S.S. and El Manawi, A.W., 2005 [18] ; Hassan et al., 2007 [19] ). This article is a step on the same road for the maximum utilization of the Egyptian talc deposits

A technological talc sample, about five tonnes, representing Bir Meseh, south of Shalatin locality of the Eastern Desert of Egypt, was kindly supplied by the National Service Sector, Ministry of Defense for investigation. Geologically, the talc deposits of Shalatine locality occur as large fragments of variable sizes enclosed in mafic-ultramafic matrix, or occur as lenses and pockets associating metasediments (Selim et al., 2005). The two associations of talc deposits are restricted to NW-SE shear zones. The rocks within the shear zones are highly brecciated, deformed and extensively altered. The delivered sample represents the previous mentioned genetic types of talc

the art of talcflotationfor different industrial

Ore characterization was carried out by overall analyses, using XRF model Axios advanced-panalytical and ore microscopy. Attrition scrubbing of the −11 mm crushed ores was carried out in the laboratory using the “Denver D12” flotation cell. In this process, the attritioned product was screened on a 74 μm screen and both oversize and undersize fractions were weighed and analyzed for loss on ignition, L.O.I. This latter size fraction was directed to further fine grinding to improve the degree of liberation of minerals, i.e. until 100% less than 22 μm. Flotation of this superfine feed was conducted in the same conventional subaeration flotation cell. Aerofroth 71 was used as a frother for talc whereas soda ash was tested as selective depressant of carbonate. In the meantime, quaternary amine was employed in the laboratory as a selective collector for talc

Complete chemical analysis of the talc sample, supported with the results of the XRD (Figure 1), indicates that it is high in undesirable ingredients, e.g. iron oxides and CaO (Table 1). It is characterized by low MgO content (25.40%), low SiO2 (45.71%), high CaO content (6.32%) and high L.O.I. (11.35%) indicating its low grade (Table 1)

Mineralogical investigation by XRD, using EVA software, shows that the main sample constitution is talc (48%), dolomite (27%), calcite (6%), chlorite, serpentine, sphene and iron oxides (19%) (Figure 1). Petrography study of the talc sample reveals that the talc sample includes four main lithological groups: steatite group, talc- carbonate group, talc-chlorite group, and ferruginated talc group ( Plate 1 ). This study shows also that the talc sample is characterized by fine-grained talc fragments with apple green color, enclosed in white color harder carbonate matrix

the art of talcflotationfor different industrial

On the other hand, Figure 2 illustrates the thermal analysis of the talc sample. Despite the single endothermic peak characteristic of talc at about 950˚C - 1000˚C, the sample demonstrates a sharp endothermic reaction peak at 600˚C associated with an exothermic reaction between 800˚C and 900˚C which is related to dolomite mineral (Figure 2). This corroborates with both the high L.O.I. and CaO contents. Chlorite presence was also confirmed by both XRD and DTA analyses

High grade steatite, the only mineral shown is talc (Medium grained talc occurs in narrow shear zone parallel to the main foliation planes), B―Photomicrograph of exclusively sheared talc (Notice, the shear foliations and the offset in coarse talc flake “Tc” (Crossed Nicols), C―Coarse flakes of talc “Tc” attacking coarse carbonate crystals “Ca” and corroding it, talc-carbonate rock (Crossed Nicols), D―Photomicrograph shows growth of well developed talc flakes at the expense of mega calcite crystal (Crossed Nicols), E―Microscopic banded structure in the talc-chlorite rock, the upper band rich in opaques and iron staining, the middle band is mainly talc, the lower band consists of talc and chlorite intergrowth (Crossed Nicols), and F-Medium-grained talc contains large amount of opaques (Plane Polarized light)

This technique was suggested as a substitute of the conventional ball or rod milling in talc beneficiation plants by taking advantage of the friable nature of talc, being at the top of Moh’s scale. The objective of this process was to achieve preconcentration of talc by fractional grinding from the harder carbonate impurities. Optimization of the process in the laboratory including verification of the attrition speed, attrition time and pulp density are shown in Figures 3-5

the art of talcflotationfor different industrial

Figure 3 illustrates the effect of varying the attritioning motor speed on both the yield and grade of both the under- and oversize products at 50% solid and an optimum attritioning time of 60 min. Evidently, the substantial increase in the process recovery from 69.3% at a motor speed of 1500 rpm to 79.5% at a speed of 2100 rpm was accompanied by an incremental increase in the preconcentrate % L.O.I

At 50% solid, 1500 rpm motor speed and 15 min. attritioning time about 50% by weight of the crushed rock reports to the −200 mesh size with a L.O.I. reaching 8.2% as compared with 14.9% in the oversize product. After 60 min. attritioning time, the weight percent of the talc preconcentrate, −200 mesh, reaches about 69.3% without a pronounced decrease in its grade (Figure 4). This technique, which sounds unconventional in talc processing

Figure 5 shows that increasing the% solid in the pulp from 50% to 70% at a motor speed of 1500 rpm and 60 min. attritioning time, the % yield of the talc preconcentrate increases to an optimum of 74.7% at 60% solid with a L.O.I. of 8.5%. But the process becomes, almost, impractical by increasing the% solid in the pulp more than that due to consolidation. Therefore, a talc preconcentrate having about 8.4% L.O.I. was obtained by attrition scrubbing of the −11 mm crushed ore at 60% solid, 1500 rpm motor speed and 60 min. attritioning time, at a yield of about 74.7%

the art of talcflotationfor different industrial

Although the talc surface has a net hydrophobic character, two additional factors must be considered in order to fully appreciate its flotation chemistry. First, there may be a significant number of hydrophilic sites on the talc surface. The second factor is that during size reduction other planes of the crystal may be exposed which do not have a net hydrophobic character. However, due to the anisotropic structure of talc, three types of surfaces will be produced: hydrophobic (faces), partially hydrophobic (faces and edges) and hydrophilic (edges). Accordingly, flotation of talc pre-concentrate for separation of carbonate was studied in the laboratory within three complementary routes as follows:

The effect of changing the impeller speed on the natural floatability of talc while changing the pulp pH showed modest recovery of the process and its independence of pH (Table 2). This results in a concentrate assaying about 6% L.O.I. with a recovery of about 32% at an impeller speed of 1200 rpm

Talc mineral, as a predominantly hydrophobic solid, may still possess a number of polar sites. When a meniscus recedes from such a surface it leaves few (if any) isolated water molecules on non-polar sites but clusters of them are around polar sites. This concept explains why talc mineral needs only a fraction of a monolayer of frother to render it floatable. Floatation results as a function of frother concentration at pH 8 (the optimum pH of the natural floatability) are shown in Table 3. By adding Aerofroth 71, the recovery increases significantly with increasing frother concentration but this happens on the prejudice of the grade of the concentrate. By using 300 g/t of the frother a talc concentrate assaying 6.7% L.O.I. was obtained with a yield recovery of 64.71%

the art of talcflotationfor different industrial

When using quaternary amine as a selective talc collector, the grade of concentrate is not encouraging (Table 4). Talc concentrate assaying 7.78% L.O.I. was obtained with a yield recovery of 86.88%. But in the presence of soda ash as a selective carbonate depressant, flotation indices relatively improve (Table 5). Cleaner talc concentrate assaying 6.5% L.O.I. but with a lower recovery of 56.35% was obtained using 0.5 kg/t of soda ash and 0.2 kg/t quaternary amine at natural pH

floatability of talc, addition of frother, collector and depressant. Table 6 shows that three concentrates of talc were produced assaying 5.83%, 6.33% and 7.21% L.O.I. with yield recoveries of 24.22%, 23.17% and 7.32%, respectively

Further grinding of the flotation feed sample was decided to improve these results. Table 7 shows the results of a step flotation of the −22 μm superfine talc pre-concentrate. Using the same conventional type “Denver D 12” flotation cell, this latter superfine feed responded easily to natural floatability without the use of a collector where a first concentrate was obtained assaying 6.6% L.O.I. with a yield recovery of 28.48%. By using soda ash and frother, second concentrate assaying 7.60% L.O.I. was obtained with a yield recovery of 34.43% (Table 7). The needle-like crystals of talc concentrate is shown in Figure 6

the art of talcflotationfor different industrial

Attrition scrubbing of the −11 mm crushed talc sample was proved to be an unconventional process for separation of the harder carbonate gangue minerals in the +74 μm oversize product and in the production of talc superfine −22 μm as well. Minimization of the carbonate content of talc pre-concentrate by multistage flotation was optimized in the laboratory through natural floatability of the talc and application of a selective carbonate depressant. Fine grinding of the talc to less than 22 μm was imperative to improve the recovery of the process. Flotation of such superfine talc using the conventional “Denver” sub-aeration flotation cell proceeded well with the addition of frother and carbonate depressant without the addition of talc collector. A concentrate assaying 54% SiO2, 33.56% MgO, 1% Fe2O3, 1.44% CaO, and 6.9% L.O.I. with a recovery of 62.91% was obtained. This satisfies the world market requirements for plastics, paints, ceramics and paper also since its brightness is 89.0 and its oil absorption is 20. Evaluation of other flotation products indicates their suitability for both carpets and roofing purposes

Tawfik Refaat Boulos, Suzan Sami Ibrahim, Ahmed Yehia (2016) The Art of Talc Flotation for Different Industrial Applications. Journal of Minerals and Materials Characterization and Engineering,04,218-227. doi: 10.4236/jmmce.2016.43020

(pdf) glasssand flotation for iron impurity removal

Attrition Cells/Scrubbers are designed to scrub the surfaces of particulates, liberate deleterious materials and break down pretend particulates associated with durability, such as hard-pan clays. The top size of the feed is typically of up to 1/2” (12 mm). Surface contaminants, such as clays, oxides and chemicals, are removed by particle-on-particle attrition generated by a series of rotating paddles inside the Attrition Cells that have been sized to suit the application.  

This style of scrubber is ideal for industrial (frac, glass, sports) and mineral sands to meet turbidity and color test requirements. They also allow more efficient downstream separation, such as in flotation and electrostatic/electromagnetic separation. Attrition Cells/Scrubbers can handle high plasticity clays in high shear and aggressive scrubbing environments.

McLanahan Attrition Cells/Scrubbers are designed to be robust. They feature heavy-duty direct-drive gearboxes that eliminate the slip often associated with V-belt driven units. They also feature field-replaceable rubber liners, shaft protection and individually replaceable paddles for longer wear life and reduced maintenance downtime. 

McLanahan's in-house Applications Research Laboratory performs lab-scale testing of sample material to evaluate the most appropriate process for an application, whether it's surface contamination or durability issues, as well as to determine the effectiveness of that process. This ensures the right size and quantity of Attrition Cells/Scrubbers are selected to achieve the most efficient operating configuration in the field. McLanahan offers multiple configurations of Attrition Cells, including a variety of sizes and shapes, as well as unique adjustable internal geometry to provide maximum scrubbing and increase the quality of the final product. 

(pdf) glasssand flotation for iron impurity removal

McLanahan has more than 30 years of experience with Attrition Cells/Scrubbers and many units installed in a variety of applications. Our experienced geological and process engineering staff can assist with your application needs to ensure efficiency and profitable production. 

Attrition Cells/Scrubbers are typically fed by Separators™, Hydrosizers™ or Dewatering Screens to present the material at a high density to achieve the best scrubbing action possible. Operating densities vary depending on the application but are typically in the range of 72-75% solids by weight. To maintain correct operating density, dilution water is automatically added at rising power draw. In the event of excessive power draw, the motor shuts off to protect the motor, gearbox and shaft/paddles

Attrition Cells/Scrubbers are configured to provide the most efficient performance, producing a high shear environment in which particle-on-particle scrubbing scours the surfaces and liberates deleterious materials. Due to the higher levels of materials passing through the unit too quickly to be fully processed, multiple Attrition Cells/Scrubbers are used in series.

(pdf) glasssand flotation for iron impurity removal

Material enters the Attrition Cell/Scrubber at the bottom and by displacement passes up through the tank, being subject to high velocity axial and radial motion to best provide particle-on-particle scrubbing action. The material overflows the Attrition Cell at the top and passes through to the next cell in the series, where the scrubbing is repeated. A series of weirs is provided to increase or decrease the total volume being processed in an Attrition Cell/Scrubber. Retention time is based on testwork and can vary between one and eight minutes. Greater retention times may end in diminishing returns for the energy consumed and capital investment. 

In cases of severe contamination, interstage washing is used. In this type of application, the materials can be diluted and processed through a pump and Separator™ or other methods, and are then directed to the next stage for further attritioning.

The most commonly used Attrition Cell/Scrubber is a 1.7 m3 unit with multiple units in series. These can be round, square or octagonal. Larger Attrition Cells/Scrubbers are available; however, multiple smaller units are preferred due to their efficiency

(pdf) glasssand flotation for iron impurity removal

Attrition Cells/Scrubbers can be used in glass sand, frac sand, mineral sand, clay, iron ore, and sand and gravel production, as well as in the preparation of flotation feeds and reagent washing. They are used as a part of an integrated process utilizing Hydrosizers™, Hydrocyclones/Separators™ and attrition technologies, 

The typical retention time for clay removal using an Attrition Cell/Scrubber is between two and five minutes, but specifications and individual requirements vary. The only way to determine how long the retention time needs to be is to test the materials

Particle shape, size and mineralogy affect the wear life of Attrition Cells/Scrubbers, and sometimes materials of construction have to vary to suit the application. No manufacturer can guarantee wear life, but advanced knowledge of the materials being processed can help with the selection of wear materials and thicknesses to help maximize wear life. 

(pdf) glasssand flotation for iron impurity removal

In certain applications it is necessary to add chemicals to the Attrition Cell/Scrubber feed to improve the performance of the attrition process. Certain materials of construction are adversely affected by different chemistries, so it is important to consult the manufacturer before purchase and/or before the use of additional chemicals

McLanahan does not employ the use of side access to Attrition Cells/Scrubbers for safety reasons. As work components often have sharp edges, reaching inside the vessel and indexing the shaft rotation can lead to uncontrolled exposure to sharp surfaces and accidental engagement. 

Extraction of the shaft assembly allows more controlled and more complete access to the assembly to evaluate any wear or damage. This allows the maintenance crew to remove/replace worn components with the greatest level of safety. Inspection of internal surfaces can also be carried out with the shaft assembly removed

(pdf) glasssand flotation for iron impurity removal

McLanahan Attrition Cells are optimal for industrial (frac, glass, sports) and mineral sands to meet turbidity and color test requirements. They are designed to scrub the surfaces of particulates, liberate deleterious materials and break down particulates associated with durability

The leader in creating complete processing plants to produce frac sand needed in the oil and gas well drilling industry, McLanahan’s Frac Sand Plants are designed to remove clay impurities, as well as size and dewater sand. McLanahan process engineers work directly with customers to determine layout and equipment requirements for each deposit’s unique characteristics. Utilizing proven technologies, plants are engineered with the right equipment to meet each producer’s needs, including: centrifugal slurry pumps, Hydrocyclones and Separators™, Dewatering Screens, Fine Material Screw Washers, Hydrosizers®™, Attrition Scrubbers, Thickeners, and Filter Presses

heavy media separation- an overview | sciencedirect topics

Heavy media separation dates back to several centuries. Initially, a fine magnetite was used as a heavy media. In 1936, a plant was designed employing organic liquid as a heavy media for treating anthracite coal containing ore

The heavy media process is usually used for treatment of coarse coal above 9.5 mm in size. Finer coal below 9.5 mm cannot be cleaned economically in heavy medium. The settling velocities of the fine material are very low, and consequently the time required to separate the lighter coal from the heavy becomes excessive

Nowadays, magnetic field has been used as a heavy media at fineness of between 100 and 325 mesh. Separation using heavy media can be done in either conventional heavy media, thanks or in heavy media cyclones

This method involves preheating of the ore to about 400–500 °C, followed by electrostatic separation. Preheat temperature depends on the amount of the clay in the feed. If the slime associated with the ore is present, then preheating temperature increases. In these studies, the optimum preheat temperature [9] is between 200 and 350 °C

heavy media separation- an overview | sciencedirect topics

Heavy liquid separation although extensively examined, has limited commercial application. Heavy media density used in the studies is in the range of 2.02–2.12. One heavy liquid used is acetylene tetrabromide diluted to the above density with a miscible solvent. Another suitable media can be made from finely ground magnetite, which is added to brine saturated with potassium and sodium chloride

Flotation is primary used for mineral extraction from lithium ores. In this process, lithium ores are concentrated with respect to lithium oxide from 1–3% Li2O to 4–6% Li2O through heavy medium separation using dense nonaqueous liquids in a froth flotation process. Silicate ores are most widely processed using the flotation method, those products are subsequently chemically cleaned by an acid or alkaline process

In the acid cleaning process, the concentrated spodumene ore is placed in a kiln and heated to elevated temperatures between 1075 °C and 1100 °C. This process changes the naturally occurring alpha-spodumene into beta-spodumene, which can be more readily attacked by the acid. The beta-spodumene is further cooled and ball-milled. This powder is then roasted in a second kiln under an excess of sulfuric acid at a temperature between 200–250 °C. The following reaction occurs at this stage:

heavy media separation- an overview | sciencedirect topics

Once this reaction has taken place, the kiln is then leached with water. This yields a lithium sulfate product to be treated with sodium carbonate to convert it into lithium carbonate. Hydrochloric acid can then be used to react with the lithium carbonate to form lithium chloride

In the alkaline cleaning process, either a spodumene or a lepidolite concentrated ore is ground and calcined with a mixture of 3.5 parts limestone to 1 part lithium. This is done at a temperature between 900 °C and 1000 °C. In this process, the kiln is then hot-leached with water and the product is lithium hydroxide, which can be converted to lithium chloride using hydrochloric acid:

Lithium chloride is thus the source for electrolytic extraction of lithium. Metallic lithium can be obtained by the electrolysis of a melt, comprising of an equal mixture of lithium chloride and potassium chloride. A schematic diagram of this cell can be seen in Figure 1 (Freitas, 2000). Lithium chloride is fed into the cell, which is operated at a temperature between 400 °C and 420 °C. The voltage across the cell of molten lithium chloride and potassium chloride, is typically between 8 V and 9 V with a current consumption of 40 kWh per kilogram of lithium that is produced. A steel cathode with cast iron collectors and a graphite anode is employed. Tables 1 and 2 show that lithium has a lower density than the electrolytes. Therefore, the metal floats on top. The collector is helpful in the recovery of the metal. The electrical and ionic conductivities in the cell and the fluidity of the electrolyte, are critical parameters that control the material and energy balance of the process

heavy media separation- an overview | sciencedirect topics

Electrolytic lithium is refined by remelting, when the insolubles either float to the surface or sink to the bottom of the melt pot. Potassium is only slightly miscible in lithium. The remelting step produces lithium metal with less than 100 ppm of potassium

Hoshino (2015) proposed another method for the recovery of the lithium from seawater by using a Lithium ionic semiconductor as Li separation membrane (LISM).Only Li ions can significantly permeate this LISM to pass from the negative electrode side to the positive electrode side as the other ions in seawater(Na,Mg,Ca, etc.) are not permeated through LISM, Li becomes selectively concentrated on the positive electrode side. Furthermore, the LISM generates electricity, requiring no external power source. The above process has been demonstrated in the following Figure 2

A large portion of silica is produced from quartz veins and quartz sands, while other sources include sandstone deposits. In beneficiation of silica sand, relatively simple processes are used. Some of the processes include:

heavy media separation- an overview | sciencedirect topics

This process was adopted by the British Industrial Sand Company for removal of iron and other impurities from sandstone deposit. In this process a little acid was used due to the fact that iron content of the sand was about 0.5% Fe2O3. Leaching was conducted in the presence of metal chloride at elevated temperature of about 50 °C. After completion of leaching, the acid and metal chloride were removed by multiple-stage countercurrent washing and acid regeneration

This method is normally used for beneficiation of silica sand that contains mica and high-iron oxides. Attrition scrubbing is usually done using acid. The beneficiation flow sheet is presented in Figure 33.3

The flotation is performed at acid pH 2.5–3.5 and controlled with either sulfuric or hydrochloric acid. The collectors usually used are sulfonate-based collectors from Cytec 800 Series (i.e., R801, R827). Using this method, iron content of the [1] silica product is reduced to about 0.06% Fe2O3

heavy media separation- an overview | sciencedirect topics

Some of the silica sand deposits from the USA and Canada contain impurities such as pyrite, iron oxides, and feldspar. Beneficiation of silica from these deposits involves attrition scrubbing followed by three-stage flotation process [2]. In this research study a number of different reagent schemes have been examined, in various stages

Iron oxides are floated using natural petroleum sulfonate collectors (Aeroflot R840) [3] at pH 2.3–3.5. A high pulp density conditioning at 50% solids with reagents was used. Because hydrofluoric acid (HF) was always used as a feldspar activator, and being a hazardous chemical, an attempt was made to examine a non-HF flotation method [4]. Collectors ArmacT (Tallow amine acetate, Armac C (coco amine acetate)) and Duomeen TDO (n-tallow-1, 3-diaminopropene dioleate) were examined. The best metallurgical results were achieved with Duomeen TDO at pH 2.1–2.8. At this pH, it was possible to float feldspar without floating quartz

The silica sand used in the study consists of poorly sorted angular grains of clear quartz loosely cemented together by kaolinite clay. Lances of high-grade kaolinite were also present in the ore body

heavy media separation- an overview | sciencedirect topics

The flow sheet used is shown in Figure 33.5. The sand was first attrition scrubbed at about 50% solids for 20 min, followed by sizing. The fine fraction was deflocculated using Na4P2O7 followed by sedimentation, where coarse clay and fine clay (i.e., 12 μm) were separated and the fine clay was bleached and dried

The lithium ores and operating plants are found in Australia, Canada, and United States. In the other parts of the world lithium is found in China, Africa (petalite ore), and Brazil. Treatment options of spodumene and petalite largely depends on the gangue composition present in the ore. If the ore contains mica and talc, then these are floated ahead of spodumene. Several processing plants of importance are deslimed in this section

The Bernic Lake ore is relatively complex and variable within the ore body. The main minerals include quartz, feldspars, microcline, albite, and lepidolite. Major lithium minerals are spodumene with some amblygonite. The amblygonite represents a problem in recovery of spodumene as this mineral contains phosphorus, which is an impurity in production of high-grade spodumene. Initial development work started in 1978, which included pilot plant testing. Plant production was started in 1984. In the treatment flow sheet, heavy media separation was included [8]; also preflotation of amblygonite before lithium flotation. The plant flow sheet is illustrated in Figure 28.4

heavy media separation- an overview | sciencedirect topics

The metallurgical results obtained with heavy media separation are shown in Table 28.6. Approximately about 35.9% weight was rejected in the float product which contained only 3.1% Li2O of the feed. The triflow was used for heavy media separation

The amblygonite flotation involves conditioning with starch to depress spodumene and starvation addition of emulsified tall oil. In the spodumene flotation, the Na2CO3 was used as a pH modifier and collector LR19 (described in Table 28.3). The spodumene rougher and cleaning was performed at pH 9.5. The flotation metallurgical results from the heavy media product are summarized in Table 28.7

The Greenbushes is a major producer of lithium in the world. There are two ore bodies including tantalum/niobium and tin and the lithium ore body. The ore reserves are about 30 million tonnes, containing at least 7 million tonnes at 4.0% Li2O [9]

heavy media separation- an overview | sciencedirect topics

The ore is crushed to 16 mm nominal size. The ore is fed to a ball mill. The ball mill discharge is classified into 15 columns, where 250 μm fraction is removed to provide feed for desliming and flotation

The plus 250 μm fraction is screened on 800 μm screen. The plus 800 μm material is recycled to a ball mill and plus 800 μm fraction is subjected to a magnetic separation. The nonmagnetic fraction is glass grade spodumene assaying about 6.5% Li2O. The minus 250 μm fraction is deslimed to remove minus 20 μm slime followed by bulk spodumene tourmaline flotation using fatty acid collectors and soda ash for pH control (pH of 7.0–7.5). The bulk concentrate is treated by gravity followed by magnetic separation to remove tourmaline. Magnetic separation is done at 0.9 T magnetic field strength

The mill feed ore is crushed to 25 mm followed by rod mill, ball mill grinding. A fine grind is required to achieve liberation. The ball mill is operated in a closed circuit with cyclone about 300–400 g/t of NaOH is added to the mill. The ground ore is deslimed to remove 15 μm slimes. The deslimed sand is conditioned at 55% at natural pH with about 700 g/t of tall oil fatty acid. The conditioned pulp was floated at 30% solids followed by two cleaning stages. The plant flow sheet is shown in Figure 28.6

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In order to maximise the yield of the different scraps melted, they must be preprocessed to get them in the best state for handling, charging and melting. It is important to be able to charge the scrap to the furnace at a rate greater than the melt rate of the furnace. There are a number of processing techniques that can be employed to present the scrap in the most suitable form. Some scraps may require several processes

At the point of receipt all scraps will be inspected for possible contaminations and may be quarantined awaiting hand sorting. The inspection will also be looking for potentially dangerous items such as sealed containers. It is also the point at which a claim on quality or a correction to price can be made. Subsequent sorting may involve removal of free contaminants, both metallic and non-metallic, or simply segregation of different scrap types to upgrade the various qualities

Specialised methods of separation include magnetic separation, heavy media separation and eddy current separation. A significant source of aluminium scrap today is from car-shedders. A major byproduct is a material known as Zorba which consists of approx 60% aluminium together with various other nonmagnetic metals including lead, zinc, stainless steel and magnesium plus some non-metallics. Large volumes are shipped to China, where the labour cost is low, and the material is tipped out onto large tables surrounded by many operators and hand sorted. A mechanised method for this process is separation using heavy media plants where the metal is segregated based on its density. The mixed solids are placed in a liquid denser than one metal and less dense than the others. The denser material sinks whilst the less dense floats

heavy media separation- an overview | sciencedirect topics

The oldest forms of pre-processing are shearing to reduce length and baling to improve density and handling. Early baling was in small bales around a foot square, producing a dense product which can be stacked on pallets for transporting, however today the most common form is large bales approx 1 m × 1 m × 1.5 m. This highly automated process produces bales that stack well, removes the need for pallets and provides much faster baling rates so that large volumes can be processed economically

The shredding process produces a free flowing material ideally suited to subsequent pre-melting processes such as magnetic separation, heavy media separation or de-coating. Clean scrap may also be shredded to facilitate charging and melting direct into a molten bath to improve yield

Aluminium swarf contains oil and moisture which must be removed to maximise metal recovery. Drying may involve centrifuging and/or passing swarf though a barrel drier where the oils are burnt off. Once dried the swarf is then passed over a magnetic separator. In the past decade many large generators of swarf have installed equipment to briquette the swarf and in the process recover valuable cutting fluids for re-use. The briquettes do not require drying, however they will contain any free iron which is generally present in swarf to a small degree from tool wear. This may be critical for the end user if the swarf is from automotive wheels and is used back in the same alloy (e.g. A356), which has a tight iron limit of 0.2% maximum (note as well A356.1 has a limit of 0.15Fe and A356.2 has a limit of 0.12Fe)

heavy media separation- an overview | sciencedirect topics

De-coating involves the removal of paints and lacquers using pyrolysis, a form of incineration that chemically decomposes organic materials by heat in the absence of oxygen. By controlling furnace temperature and atmosphere to a level that will decompose the organics but below the melting point of the scrap, improved yields are obtained in the subsequent melting process

Drosses are frequently milled and/or screened to concentrate the recoverable metal and therefore reduce the volume of waste produced. The resultant fines may still contain some metallic aluminium, but at a concentration too low to economically recover in the melting process. The fines can however be re-directed to other industries for re-use, thus significantly reducing the amount of waste going to landfill

The secondary aluminium industry employs a range of furnaces, however the most common is oil or gas fired reverberatory furnaces ranging from 5 to 90 tonnes capacity and rotary furnaces of 2–20 tonnes capacity. Modern plants will utilise efficient oxygen enriched burners for faster melting rates

heavy media separation- an overview | sciencedirect topics

Reverberatory furnaces are box shaped and ideally suited to the melting of high yield solid scraps. More sophisticated types may be fitted with magnetic stirrers or electro magnetic pumps to improve melt rates and in large plants. Those used for casting rolling slab will also tilt for rapid pouring whilst ingot casters are usually static. Whilst reverbs, as they are commonly known, are frequently used as primary melting furnaces they are almost always used as the final alloying and casting furnace. When used as a primary melter they may be fitted with stage burners that permit the pyrolysis of the scrap to burn off the paints and lacquers prior to getting to melting temperatures thus increasing metal yield. The final alloying and casting furnace will be fitted with fluxing and degassing equipment to clean the melt prior to casting

Rotary furnaces can also be used to melt the high yield scraps, however their real forte is for melting of dross and low yield scraps under a flux cover of sodium chloride and/or potassium chloride. The flux is added to protect the scrap from oxidation and to remove the unwanted oxides. Early rotary furnaces were single pass, fixed axis furnaces where the flux was wet. Today the tilting axis double pass rotary is more common, where less flux is used and the flux is dry. The waste slag resulting from the use of salt fluxes will contain a small percentage of aluminium plus oxides and salt. Special plants exist to process this waste which in many countries is now banned from being sent to landfill. These plants recover the aluminium, salt and oxides for re-use

Other furnaces which may be used include refractory crucible and induction furnaces although these are usually for specific niche applications such as master alloys production. Sweat furnaces are also employed for recovery of aluminium from scrap that is heavily contaminated with iron. Modern plants now have furnaces with accurate temperature control which often permits the melting of moderately iron contaminated scraps with nil dissolution of the iron

heavy media separation- an overview | sciencedirect topics

Chromite ores, as might many others, be mined by open-pit and underground methods. The share of underground mining varies between countries and deposits. The extracted ore is subjected to crushing and sorting (normally rich ore containing more than 45% Cr2O3 is supplied to the processing plant, whereas lower-grades are subjected to different dressing procedures)

The main consumers of chromite ore are the ferroalloy, refractory, and chemical industries, which have different demands for the ore and the concentrates, both in terms of the impurity ingredients and in grain-size composition (Table 8.4)

A typical technological process of chromite ores enrichment includes a series of operations (Lyakishev and Gasik, 1998): screening of the input ore, slurry rinsing-off, and heavy media separation. The slurries formed are subjected to wet screening, dehydration, filtration, and drying. The major parameter, changing in these phases, is the SiO2 concentration gradually changing to <7, 5, 3, and 1%. Because these low-silica concentrates are represented by finer fractions, it is important to prepare the product in lumpy forms (pellets, briquettes). It has been recommended that fine concentrate should be granulated and roasted (~1800°C)

heavy media separation- an overview | sciencedirect topics

The most common method is gravity concentration (heavy-media separation, screw separators, and concentration tables). Aside from the gravity method (in various modifications), flotation methods are used (separately or in combination with gravity methods), as well as concentration in a strong magnetic field. Magnetic concentration in a weak field is also used to extract magnetite from chromium ore before flotation or to extract it from chromium concentrate after flotation (Kurochkin, 1988; Lyakishev and Gasik, 1998). Wet high-gradient magnetic separation is usually thought to be the most promising method for improved performance. Chromite ore can be separated in a high-strength field, despite the presence of iron impurities. The choice of method depends on several factors, primarily the type of the gangue

In some cases, separation and dressing methods are optimized to take into account other useful elements, such as PGM (platinum group metals) in South Africa, where noble metals extraction (besides chromium) is of high importance. Along with gravity-flotation and magnetic methods, hydrochemical (hydrometallurgical) technologies are being developed

Besides these ore dressing methods, combined techniques are also possible, especially when the chromite quality is low. In India, low Cr:Fe ratio chromites are briquetted with coke and selectively reduced at 1250°C. Treated briquettes are crushed, ground, and leached, leading to the higher Cr:Fe ratio concentrates with chromium extraction exceeding 95%

heavy media separation- an overview | sciencedirect topics

The authors have estimated that more than 75% of chromite ores are represented by fine fractions and the remaining share is represented by lumpy ores. Electric furnaces consume approximately two thirds of all mined chromite ore, and there the optimum operating conditions are achieved with large sorted chromite ore. For metallurgical processing of high-chromium concentrates, usually present in the finest forms, they have to be agglomerated. Although some successful experiments were made for smelting of ferrochromium in various metallurgical furnaces using fines, this technology has not yet been implemented on an industrial scale. For chromites agglomeration, three main methods are being exploited: sintering, palletizing, and briquetting

Sintering technology originates from the similar method used for iron ores agglomeration. Many combinations of ores, carbon fuels, moisture content, and binders (bentonite) have been studied. An example of different versions of sinter charges is shown in Table 8.5. The addition of iron ore depends on the required Cr:Fe ratio, fines fractions, and chromite quality

The pelletization of chromite fines and concentrates is usually based on mixing chromites, binder (bentonite), recycled material, and possibly coke fines and roasting at sufficiently high temperatures (1200° to 1300°C). It is known that roasting in air results in better pellet quality due to the oxidation of iron (2+ to 3+) taking the octahedral sites in spinel structure. A minor share of coke fines in the pellets gives the possibility of raising the temperature and gets more uniform temperature distribution inside the pellet. However, a better resistance to impact and abrasion was achieved in pellets with no fuel additions. During roasting, sulfur is removed from the pellets by 70% to 80% (due to oxidation of sulfides like pyrite). The remaining sulfur is of the sulfate type (magnesium and calcium sulfates). Some examples of pelletization technology parameters by different sources are shown in Table 8.6

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Briquetting as a method for agglomeration of fine fractions is widely used in ferrous and nonferrous metallurgy. Unlike sintering or pelletization, it is possible to make briquettes of single component (monobriquettes). In many cases, briquetting was reported to be commercially competitive with sintering or pelletization—the latter is associated with high capital investment, high cost of the grinding and roasting, demand for low SiO2 content because of possible sintering of pellets when they are roasted in rotary kilns, and so on. The clear environmental advantage of briquettes versus lumpy ore is in the reduction of dust emissions by 1.5 to 2.5 times

In developing a technology for briquetting of chromite ore, it is important not only to study the mineralogical and grain-size characteristics but also to make a proper choice of the type and quantity of the binder and the conditions for pressure and heat treatment of raw briquettes (Sen et al., 2010). It should be noted that it is very difficult to make recommendations about briquette quality with a particular charge and processing parameters, as well as whether they would be suited for effective smelting of ferrochrome in a submerged arc electric furnace (Pavlov et al., 2010). For example, briquettes in the furnace bath are also a current conductor, so extra coke in briquettes may lead to their premature destruction in the case of high current density. On the other hand, briquettes produced by this method are a good regulator of electric resistance in the charge

Different compositions have been suggested for briquetting chromites using coal, tar resin, sulfite solution (lye), lime, and so on. One of the recommended briquetting methods is as follows (although it should be remembered that no defined remedy recipe exists for briquetting all types of chromite ores). The ore of the 6 to 10-mm fraction is dried and mixed with hydrated lime to which mixture molasses is added at 35° to 40°C. The formed briquettes are 2 to 5 inches long, 1 to 2 inches thick, and 1.5 to 2.5 inches wide, and they are stored in piles; their strength increases slowly with holding, reaching maximum values (8 to 25 MPa) after 10 to 12 h. The briquettes retain their strength values even in humid conditions (for shipping and handling, >8 MPa is considered a sufficient limit). The exact mechanism behind the process of strengthening is not known, but some have speculated that it is related to calcium hydroxide carbonization or molasses transformations

heavy media separation- an overview | sciencedirect topics

Most mineral processing plants are represented by the flow sheet shown in Fig. 11. Simpler operations, such as a quarry producing aggregate, would involve only the initial stages of size reduction. Conversely, a more complex plant, producing a number of concentrates, requires a series of concentrating circuits

Rod and ball mills have larger reduction ratios. Because rod mills provide some internal sizing action, they are commonly operated in open circuit. There is an increasing tendency to use an extra stage of crushing instead of a rod mill because crushers are more energy efficient

Wet ball mills are usually operated in closed circuit to control the product size distribution. At these fine sizes, only classifiers have sufficiently high capacities. Because of their low cost, hydrocyclone classifiers are virtually always used. Unfortunately, they can be very inefficient; not only do they have the inherently spread performance curve of a sedimentation classifier, but at the high pulp Figure 11 Representation of mineral processing circuit. densities used, bypassing markedly lowers the efficiency. Two-stage classification is gradually being adopted, with recently developed polyurethane and sandwich screen surfaces being potential alternatives

heavy media separation- an overview | sciencedirect topics

In new operations, semiautogenous grinding is now as common as the conventional size reduction shown in Fig. 11. In such plants, the crushing and grinding equipment shown in Fig. 11 is replaced by a single stage of (primary) crushing, followed by a SAG mill operating in closed circuit with hydrocyclone classifiers

The purpose of the size reduction circuit is to achieve liberation to allow concentration. Because some ores contain massive mineralization or because the gangue mineral liberates at a coarser particle size, some plants employ preconcentration before the valuable is fully liberated. Heavy media separations are usually used between crushing stages, but a few instances of conventional gravity preconcentration after crushing have been reported

Because reduced performance curves represent separator efficiency, these curves can be used to compare separators. In general, however, efficiency (as indicated by the steepness of the reduced performance curve) and throughput decrease with decreasing particle size. Although each separator tends to have its own optimum particle size range, comparisons between separators must be made at the same particle size

heavy media separation- an overview | sciencedirect topics

With finer particle sizes (particularly those encountered in flotation), efficiencies become so low that single stage treatment is inadequate. Instead, roughing, cleaning, and scavenging stages are needed (Fig. 11)

Roughers aim to recover liberated valuable and reject middlings and liberated gangue to the scavengers, which recover a concentrate containing the middlings, and a tailings of liberated waste. This scavenger concentrate is then subjected to regrinding to increase liberation. Traditional practice was to return the ground material to the rougher; modern practice is to treat it in a secondary circuit more appropriate to the reduced particle size, and also to prevent massive swings in the circulating load through the rougher

In reality, at each stage of separation, not all particles report to their correct outlet stream. Instead, there are misplaced particles that go to the wrong outlet. Consequently, the rougher concentrate is sent to a cleaning stage to recycle the misplaced particles (a procedure that of course also generates its own misplaced particles). When selectivities are very low, as is typical of nonsulfide flotation, additional recleaner stages may be needed. Although extra complexity may improve the separation, the improvements achieved must justify the cost of the additional equipment

heavy media separation- an overview | sciencedirect topics

Because any given item of equipment is designed for a specific feed rate and particle size, variations in the feed rate and the size distribution of particles being treated should be minimized. Thus, circuits should be as simple as possible, with recycle minimized, since fluctuations in a recycle stream can become magnified and cause marked variations in the flow rate through, and an expansion of the particle size range being treated in, a given item of equipment. In turn, this reduces the separation efficiency

Because output depends on grade and recovery, determination of optimum plant capacity (before or after startup) is a very complex issue. Some plants have combined concentrate grade and recovery with the smelter schedule and use this to maximize the profit per tonne of input. Others have suggested that the profit from the plant should be maximized via high throughput and consequential high tailings losses. In reality, the subject should be viewed in terms of the economics of the whole mining, concentrating, and smelting operation, under which the analysis becomes exceedingly complex, because of the effect of outside parameters and the difficulties in defining “optimum.”

Manganese occurs in nature in the form of minerals. More than 300 minerals are said to contain some manganese, but only a small number have high manganese content. The manganese mineralogy is complex because manganese occurs in divalent, trivalent, and tetravalent states. The most common manganese minerals are oxides, carbonates, and, appearing less frequently, silicates and sulfides (Matricardi and Downing, 1995). Manganese minerals of significant abundance and economic importance are listed in Table 7.1

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Braunite and braunite II are common complex silicate minerals usually occurring in association with bixbyite, hausmannite, and pyrolusite in deposits such as the Postmasburg and Kalahari manganese deposits of South Africa where braunite is the principal manganese mineral. Rhodochrosite is a common carbonate mineral in various ores

There are only a limited number of workable deposits of manganese ores. The most important land-based manganese ore deposits are located in the Republic of South Africa, Australia, Gabon, Brazil, China, India, and in the Commonwealth Independent State (CIS) countries of Ukraine, Kazakhstan, and Georgia. The manganese ores are characterized by their content of manganese, iron, and various impurities. The main types of ores are metallurgical (>35% Mn; high-grade ores with a manganese content above 48% are within this category), ferruginous (15% to 35% Mn; high levels of iron), and mangano-ferrous ores (in fact, iron ores with 5% to 10% Mn). The metallurgical ores are mainly used for direct production of high carbon ferromanganese and silicomanganese alloys, whereas the last two categories are used especially in blast furnaces for adjusting the manganese content of produced pig iron. There might be a substantial variation of ore composition even within the common deposit. For example, Georgian Tchiatura-oxide type ores have 15% to 43% Mn, 13% to 58% SiO2, 2% to 4.5% Fe2O3, and 0.7% to 5.5% Al2O3 with the average manganese content ~27% (Gasik et al., 2009; Matricardi and Downing, 1995)

Metallurgical grade ores are produced from open pit and underground operations by conventional mining techniques. Ores are crushed and screened, and washed if necessary. Heavy media separation can be used for ores with a high content of silica and alumina gangue. The average manganese recovery in this operation is usually between 60% and 75%

heavy media separation- an overview | sciencedirect topics

Metallurgical grade manganese ores contain typically 40% to 50% manganese. Another important parameter is the manganese-to-iron ratio (Mn/Fe), which is required to be >7.5 by weight for the production of standard ferromanganese alloy with 78% Mn. Extra iron might always be introduced as steel chips and recycled scrap. There are also limitations on alumina and silica contents, as excessive slag formation in the furnace increases the electric energy consumption. Ores and concentrates with more than 10% SiO2 are suitable for use in SiMn production. In some deposits, high phosphorus content is also a concern, and it must be removed before smelting because most of the phosphorus remains in the finished product. South African manganese ores are characterized by low phosphorus content, but, for example, Nikopol ore deposits (Ukraine) have 0.15% to 0.30% P in oxide-type ores and up to 0.6% P in carbonate-type ores (Gasik, 1992). Other physical and chemical properties are also important, such as the level of volatiles and the excess oxygen content. Sulfur is not a problem, neither for metallurgical nor for environmental reasons, as sulfur forms manganese sulfide, which is dissolved and usually removed with the slag

Most of the mines have sinter plants, where fines are agglomerated. Sintered material is well suited for use in ferromanganese furnaces because it is mechanically strong and thermally stable, allowing the gas to disperse evenly throughout the preheating and prereduction zone. The sintering also results in saving energy if the ore is of the carbonate type. If, on the other hand, oxide-type ores are sintered, most of the beneficial heat from the exothermic prereduction that usually takes place inside the furnace is lost and the energy consumption will increase. However, the use of fluxed sinter, by the addition of dolomite or MgO-contained materials, has been introduced and shown to improve both sinter plant and smelting operations (Kutsyn et al., 2012)

A blend of manganese ores is, in most cases, used when manganese ferroalloys are produced either in electric submerged arc furnaces or in blast furnaces. The choice of ores depends on chemical and physical properties as well as on economic factors. Table 7.2 shows the average analyses of some important metallurgical ores (Gasik, 1992; Gavrilov and Gasik, 2001; Matricardi and Downing, 1995; Olsen et al., 2007; Samuratov et al., 2010; Tangstad et al., 2004). It is evident that there are important differences in the chemical composition of the various ores. For example, some ores have an unfavorable Mn/Fe ratio but rather low phosphorus content, so a proper ore dressing process must be applied on a case-by-case basis

heavy media separation- an overview | sciencedirect topics

After mining, ore is crushed and screened into various particle size fractions ranging from fines (<6 mm) to lump ore (<75 mm). The proportion of fines is often as high as 30% to 70% of the total. Screened ores are upgraded by various methods to produce concentrates. The most common physical separation methods are washing, high-intensity magnetic separation, separation by gravity concentration, and separation by flotation, which makes use of the different surface properties of the minerals. An example for particle size distribution for Nikopol ore concentrates is shown in Table 7.3 (Gasik, 1992)

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Gold mining equipment is mainly consisted of vibrating feeder, jaw crusher, ball mill classifier, magnetic separator, flotation … Gold milling machine – Gold Ore Crusher About ” gold milling machine “ Mining equipment for mineral extraction and screening operations equipment, usually including the mining equipment and …

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