methods of physical beneficiation of an ore

the 7 most useful manganese ore beneficiation methods | fote machinery

the 7 most useful manganese ore beneficiation methods | fote machinery

The data recorded by Statistics in 2020 shows that although in 2019 manganese ore price fell to the bottom, the price in 2020 still gets increased to 4.5 U.S. dollars per metric ton unit CIF even under the impact of COVID-19. Manganese ore prices are forecast to remain at global prices by 2020 over the next two years, which is good news to manganese ore suppliers.

Besides, Justin Brown, managing director of Element 25said Manganese has the traditional end uses in steel, and that market is fairly stable". As people's demand for laptops and electric cars increases, the output of lithium batteries has also soared, and the most important element in lithium batteries is manganese.

Manganese ore after the beneficiation process is applied in many respects in our daily lives. Of annual manganese ore production, 90 percent is used in steelmaking, and the other 10 percent is used respectively in non-ferrous metallurgy, chemical industry, electronics, battery, agriculture, etc.

In the metallurgical industry, manganese ore is mostly used for manganese-forming ferroalloys and manganese metal. The former is used as deoxidizers or alloying element additives for steelmaking, and the latter is used to smelt certain special alloy steels and non-ferrous metal alloys. Manganese ore can also be used directly as an ingredient in steelmaking and ironmaking.

When smelting manganese-based iron alloys, the useful elements in manganese ore are manganese and iron. The level of manganese is the main indicator for measuring the quality of manganese ore. The iron content is required to have a certain ratio with the amount of manganese.

Phosphorus is the most harmful element in manganese ore. The phosphorus in steel reduces the impact of toughness. Although sulfur is also a harmful element, it has a better desulfurization effect during smelting, and sulfur is volatilized into sulfur dioxide or enters the slag in the form of calcium sulfide or manganese sulfide.

Applications in Metallurgy Manganese content (%) Ferromanganese (%) Phosphorus manganese (%) Low carbon ferromanganese 36%40% 68.5 0.0020.0036 Carbon Ferro Manganese 33%40% 3.87.8 0.0020.005 Manganese Silicon Alloy 29%35% 3.37.5 0.00160.0048 Blast Furnace Ferromanganese 30% 27 0.005

In the chemical industry, manganese ore is mainly used to prepare manganese dioxide, manganese sulfate, and potassium permanganate. It is also used to make manganese carbonate, manganese nitrate and manganese chloride.

Since most manganese ore is a fine-grained or fine-grained inlay, and there are a considerable number of high-phosphorus ore, high-iron ore, and symbiotic beneficial metals, it is very difficult to beneficiate.

At present, commonly used manganese ore beneficiation methods include physical beneficiation (washing and screening, gravity separation, strong magnetic separation, flotation separation, joint beneficiation), chemical beneficiation (leaching method) and fire enrichment, etc.

Washing is the use of hydraulic washing or additional mechanical scrubbing to separate the ore from the mud. Commonly used equipment includes washing sieves, cylinder washing machines and trough ore-washing machine.

The washing operation is often accompanied by screening, such as direct flushing on the vibrating screen or sifting the ore (clean ore) obtained by the washing machine to the vibrating screen. Screening is used as an independent operation to separate products of different sizes and grades for various purposes.

At present, the gravity separation is only used to beneficiate manganese ore with simple structure and coarse grain size and is especially suitable for manganese oxide ore with high density. Common methods include heavy media separation, jigging and tabling dressing.

It is essential to recover as much manganese as possible in the gravity concentration zone because its grinding cost is much lower than the manganese in the flotation process, and simple operations are more active.

Because of the simple operation, easy control and strong adaptability of magnetic separation can be used for dressing various manganese ore, and it has dominated the manganese ore dressing in recent years.

Gravity-magnetic separation plant of manganese ore mainly deals with leaching manganese oxide ore, using the jig to treat 30~3 mm of cleaned ore can obtain high-quality manganese-containing more than 40% of manganese. And then can be used as manganese powder of battery raw material.

The jigging tailings and less than 3 mm washed ore are ground to less than 1mm, and then being processed by strong magnetic separator. The manganese concentrate grade would be increased by 24% to 25%, and reaches to 36% to 40%.

Adopting strong magnetic-flotation desulfurization can directly obtain the integrated manganese concentrate product; the use of petroleum sodium sulfonate instead of oxidized paraffin soap as a collector can make the pulp be sorted at neutral and normal temperature, thus saving reagent consumption and energy consumption.

The enrichment of manganese ore by fire is another dressing method for high-phosphorus and high-iron manganese ore which is difficult to select. It is generally called the manganese-rich slag method.

The manganese-rich slag generally contains 35% to 45% Mn, Mn/Fe 12-38, P/Mn<0.002, and is a high-quality raw material to manganese-based alloy. Therefore, fire enrichment is also a promising method for mineral processing for low-manganese with high-phosphorus and high-iron.

Manganese ore also can be recovered by acid leaching for production of battery grade manganese dioxide for low-manganese ores. Leaching of manganese ore was carried out with diluted sulphuric acid in the presence of pyrite in the temperature range from 323 to 363 K.

After processed by hydraulic cone crusher, the smaller-sized manganese ore would be fed to grinding machine- ball mill. It can grind the ore to a relatively fine and uniform particle size, which lays a foundation for further magnetic separation of manganese ore.

It is indispensable grading equipment in the manganese ore beneficiation plant. Because by taking advantage of the natural settling characteristics of ore, a spiral classifier can effectively classify and separate the manganese ore size to help control the amount of grinding required.

The flexibility of flotation is relatively high. You can choose different reagents according to the type and grade of the ore. Although the entire process of froth flotation is expensive, it can extract higher-grade manganese ore.

The magnetic separator is a highly targeted magnetic separation device specially developed for the properties of manganese ore. The device not only has the advantages of small size, lightweight, high automation, simple and reasonable structure, but also has high magnetic separation efficiency and high output.

If you want to beneficiate high-grade manganese ore and maximize the value of manganese concentration, Fote Company is an ore beneficiation equipment manufacturer with more that 35-years designing and manufacturing experience and can give you the most professional advice and offer you all machines needed in the ore beneficiation plant (form crushing stage to ore dressing stage). All machines are tailored to your project requirements.

As a leading mining machinery manufacturer and exporter in China, we are always here to provide you with high quality products and better services. Welcome to contact us through one of the following ways or visit our company and factories.

Based on the high quality and complete after-sales service, our products have been exported to more than 120 countries and regions. Fote Machinery has been the choice of more than 200,000 customers.

4 beneficiation processes to obtain aluminum from bauxite | fote machinery

4 beneficiation processes to obtain aluminum from bauxite | fote machinery

Aluminum products are one of the most widely used metals. The current output and consumption of aluminum (in tons) is second only to steel and has become the second-largest metal for human application.

Bauxite is mainly used to extract aluminum. About 85% of bauxite can be refined into alumina and then smelted into aluminum, 8% for chemical alumina, and 7% for refractory materials, proppants, and cement.

Ore washing is the simplest and most effective method to improve the bauxite aluminum-silicon ratio by about 2 times. But you need to combine the ore washing process with other methods including classification -Manual selection process.

3Control the concentration of the pulp, adjust the parameters of the classification equipment to achieve the separation of coarse and fine particles, and reduce the lower limit of recycled particle size.

1Because collecting agent contains the surface-active substances, the foam of each operation of bauxite flotation is very sticking and big-volume. So, the general quantity of water will consume alarge amount of foam flushing waters, finally reducing the concentration of the flotation system.

In addition to aluminum and iron minerals, high iron bauxite is also accompanied by valuable metals such as gallium and vanadium, of which Ga content is 0.0044% ~ 0.0070%, V205 content is 0.148% ~ 0178%.

1However, the content of aluminum and iron is relatively low so that whether it is a single aluminum ore or a single iron ore, it is difficult to meet the basic requirements of industrial applications.

2Besides, the iron and aluminum minerals are embedded in a very fine grain size. Most minerals are poorly crystallized, some are colloidal and cemented with each other, and the embedding relationship is extremely complicated.

The chemical method means that we should fully dissociate aluminum minerals and silicon minerals in bauxite. The physical method uses classification equipment for bauxite concentrate. Outstanding features of the combination of the two ways:

As a leading mining machinery manufacturer and exporter in China, we are always here to provide you with high quality products and better services. Welcome to contact us through one of the following ways or visit our company and factories.

Based on the high quality and complete after-sales service, our products have been exported to more than 120 countries and regions. Fote Machinery has been the choice of more than 200,000 customers.

beneficiation - an overview | sciencedirect topics

beneficiation - an overview | sciencedirect topics

Thermal beneficiation is the use of combustion to reduce the level of carbon in the ash. Thermal beneficiation also eliminates ammonia issues and can improve fineness and uniformity. Successful thermal beneficiation technologies have been commercially deployed since 1999 (Keppeler, 2001). This technology produces more than a million tons of marketable fly ash per year in the eastern United States. There are two technologies that can be considered proven: the first is PMI's Carbon Burnout (CBO) system, based on dense phase fluidized bed combustion; and the second is SEFA Group's STAR technology, based on dilute or entrained fluidized bed combustion.

The ability of thermal beneficiation to improve ash quality is truly impressive. It is a proven, highly flexible technology that can operate on a variety of ash types with a very wide range of carbon concentrations and sizes. It produces an ash that is low or even free of carbon. It also eliminates ammonia from fly ashes impacted by nitrous oxide controls or opacity treatments. The process may improve fineness by eliminating coarse carbon and liberating ash trapped within.

Thermal beneficiation is a combustion process and may require additional air emission permitting. If not integrated into the power plant, it will also require its own emission control system. It is by far the most expensive of all the technologies considered. A facility can cost tens of millions of dollars, which suggests that it would be more attractive for larger power plants with access to large and stable markets. The construction of a thermal beneficiation facility may require significant plant modifications and systems integration; however, it does not specifically target ash fineness and uniformity.

Dry beneficiation has two important advantagessaving water, a valuable resource, and no tailings pond and subsequently, no leaching of the trace/toxic elements into ground water. In dry beneficiation of coal, coal and mineral matter are separated based on differences in their physical properties such as density, shape, size, luster, magnetic susceptibilities, frictional coefficient, and electrical conductivity [2325]. Dry beneficiation gives a clean coal as well as reduces some of the polluting elements associated with minerals. It cannot remove the inorganic matter in coal present as salts resulting from the marine environment during coalification. Azimi etal. [26] evaluated the performance of air dense mediumfluidized bed separator in removing trace elements, such as Hg, As, Se, Pb, Ag, Ba, Cu, Ni, Sb, Co, Mn, and Be. Their study revealed the association of Pb, Ag, Ba, Cu, Mn, and Be with ash-forming minerals. Elements such as As, Se, and Sb showed some organic bonding. High rejection of Hg was achieved through dry beneficiation of coal where Hg is mostly associated with pyrites.

Beneficiation of copper ores is done almost exclusively by selective froth flotation. Flotation entails first attaching fine copper mineral particles to bubbles rising through an orewater pulp and, second, collecting the copper minerals at the top of the pulp as a briefly stable mineralwaterair froth. Noncopper minerals do not attach to the rising bubbles; they are discarded as tailings. The selectivity of the process is controlled by chemical reagents added to the pulp. The process is continuous and it is done on a large scale103 to 105 tonnes of ore feed per day.

Beneficiation is begun with crushing and wet-grinding the ore to typically 10100m. This ensures that the copper mineral grains are for the most part liberated from the worthless minerals. This comminution is carried out with gyratory crushers and rotary grinding mills. The grinding is usually done with hard ore pieces or hard steel balls, sometimes both. The product of crushing and grinding is a waterparticle pulp, comprising 35% solids.

Flotation is done immediately after grindingin fact, some flotation reagents are added to the grinding mills to ensure good mixing and a lengthy conditioning period. The flotation is done in large (10100m3) cells whose principal functions are to provide: clouds of air bubbles to which the copper minerals of the pulp attach; a means of overflowing the resulting bubblecopper mineral froth; and a means of underflowing the unfloated material into the next cell or to the waste tailings area.

Selective attachment of the copper minerals to the rising air bubbles is obtained by coating the particles with a monolayer of collector molecules. These molecules usually have a sulfur atom at one end and a hydrophobic hydrocarbon tail at the other (e.g., potassium amyl xanthate). Other important reagents are: (i) frothers (usually long-chain alcohols) which give a strong but temporary froth; and (ii) depressants (e.g., CaO, NaCN), which prevent noncopper minerals from floating.

Beneficiation of complex base metal sulfide ores is based on selective production of individual clean concentrates of copper, zinc, and lead. Sphalerite flotation through copper activation becomes complicated when other minerals such as pyrite can get inadvertently activated.

Adsorption density of cells of P. polymyxa was found to significantly higher on pyrite than on sphalerite irrespective of pH. Adsorption on sphalerite was the highest in acidic pH regions only (26), beyond which cell adsorption decreased steeply.

Flocculationdispersion behavior of pyrite and sphalerite was seen to be influenced by interaction with bacterial cells and their metabolic products as a function of pH, cell density, and bioreagent concentrations. For example, more than 90% of pyrite particles were observed to be flocculated and settled at pH 89 in the presence of bacterial cells, while sphalerite was preferentially dispersed. Similarly, interaction with EBP isolated from metabolites promoted selective flocculation of pyrite and dispersion of sphalerite. On the other hand, interaction with ECP was not very effective in separation of pyrite from sphalerite because the selectivity ratio was very poor. Pyritesphalerite separation can be effectively achieved through selective bioflocculation of pyrite and dispersion of sphalerite using either bacterial cells or bioproteins.

Pyrite can also be selectively depressed through bioflotation after bacterial conditioning. Flotation tests using 1:1 mixtures of pyrite and sphalerite indicated that prior bacterial interaction followed by xanthate conditioning and copper activation resulted in preferential flotation of only sphalerite, while pyrite was depressed.

Pyrite could also be similarly removed from galena because differential adsorption and surface chemical behavior of P. polymyxa cells as well as proteins and polysaccharides were also observed on pyrite and galena as well. Selective bioflocculation in the presence of either bacterial cells or extracellular proteins could selectively flocculate pyrite from pyritegalena mixtures. Galena was also found to be selectively flocculated after interaction with exopolysaccharides. Similarly selective flotation of galena along with efficient pyrite depression could be attained after interaction with extracellular proteins.

A. ferrooxidans have been used to demonstrate selective pyrite depression from a low-grade leadzinc ore. Both sphalerite recovery and zinc grade in the floated sphalerite concentrate were enhanced by bacterial cells in the absence of conventionally used cyanides [48].

Ore beneficiation refers to the selection and collection of higher-grade ore fragments or rejection of lower-grade fragments from ROM ore. The upgraded ore will have a higher grade, and therefore require a smaller-scale processing plant, perhaps with different technology, compared to ROM ore. Ore beneficiation is only worthwhile if the majority of the uranium is retained and the majority of the mass is rejected.

In the earliest times of uranium mining hand sorting was employed, based on visual appearance or simple gamma scanning. In more recent times, mechanical sorting based on physical, mineralogical, or radiometric characteristics are employed.

At the Cluff Lake uranium mine and mill in Canada, in phase 1 operations high-grade ore was fed to a gravity concentration plant with jigs and vibrating tables. The concentrate averaged over 30% U (Schnell and Corpus, 2000). The gravity concentrator rejects were stored and retreated later (see Section 6.5.1).

Flotation (sometimes spelled floatation) separates mineral grains that respond differently when air bubbles are forced through a suspension in water with chemical additives, causing certain minerals to rise with the froth, from which they can be collected in a concentrated form. It was used in some Canadian uranium mines in the 1980s (eg, Muthuswami et al., 1983) and has been investigated in India (eg, Singh et al., 2001). It is used at the Olympic Dam copperuraniumgold mine to separate sulfidic copper-bearing minerals (Alexander and Wigley, 2003) and only incidentally for uranium minerals; uranium is recovered from the reject stream of the flotation circuit. Some recent investigation of the technique for application to multimetallic ores containing uranium is described by Kurkov and Shatalov (2010).

Shatalov et al. (2001) report that the automated radiometric ore separating was widely adopted in former Eastern Bloc countries starting in 1955. Variants and improvements up to 2000 are discussed. Radiometric sorting has been used in recent times in Ukraine (OECD-NEA/IAEA, 2014, p. 426). Radiometric sorting trials at Ranger mine in Australia and Rssing in Namibia are reported by Schnell (2014), who also comments that [G]ravity separation has been applied to uranium ores in the past with some success, but this was associated with radiation issues (cf. Section 6.5.1, where it was used with very high-grade ore). Lund et al. (2007) mention radiometric sorters in use historically in Australia and South Africa.

A form of upgrading by physical means, rotary scrubbers, at the Langer Heinrich uranium mine in Namibia is described by Marsh (2014), who states that the rejected oversize Barren Solids will contain 4050% of the solids mass but only 510% of the uranium in the ROM feed.

When the price of uranium was high in the mid-2000s, there was relatively low interest in upgrading, rather treatment of low-grade ore was considered feasible and pursued (cf. Lund et al., 2007). However, with lower prices since 2010, more experimentation is being reported. For example, ablation can remove uranium-rich mineral crusts from some sandstone ores (Coates et al., 2014) with some ore types; Scriven (2014) cites the ablation technique resulting in rejection of 9095% of the unprocessed ore mass but with a loss of only 510% of the uranium originally present. Another process under development (Becker et al., 2015) is for certain low-grade, surficial ores. It can reportedly increase the ore grade by a factor of 30 times or more without the use of chemicals, producing an inert waste and providing a leach feed suitable for acid leaching, although details of this second process were not yet released at that time. To date, neither has been undertaken at a commercial scale.

In tin beneficiation, the main new technology being adopted is the high-gravity concentrator, examples being the Kelsey jig, Falcon and Knelson concentrators, and the Mozley multigravity separator. Radical change in tin smelting and refining technology is not expected. In smelting, use of the TBRC and the Sirosmelt technologies will be more widely adopted, using fuming instead of reduction smelting for second-stage processing. Economies of scale are leading to the dominance of a few large smelters in countries such as China, Malaysia, and Bolivia. Refining technology will in general continue to rely on the same chemical principles, but will see greater adoption of automated technology such as the centrifuge for dross removal, and the vacuum process. Hydrometallurgical technologies may make an impact with developments in ion exchange, solvent extraction, and biooxidation and reduction.

Microbially induced mineral beneficiation involves three strategies, namely, selective bioleaching of the undesirable mineral from an ore or concentrate, selective flotation of the mineral, or selective dispersion/flocculation. Such microbially induced beneficiation will find applications in a number of areas such as:

Besides bioleaching using Acidithiobacillus bacteria and bioremediation using SRB, many mining organisms which inhabit ore deposits find applications in mineral beneficiation such as microbially induced flotation and flocculation. Acidithiobacillus spp can be used also to bring about microbially induced flotation and flocculation of minerals. Heterotrophic bacteria such as Paenibacillus polymyxa and Bacillus subtilis, yeasts such as Saccharomyces cerevisiae, and SRB such as D. desulfuricans can be used to bring about surface chemical changes on minerals, Principles and examples of microbially induced mineral beneficiation processes are illustrated in Chapter 10, Microbially Induced Mineral Beneficiation. Experimental protocols for such applications are illustrated below: [1]

Fully grown bacterial culture is centrifuged at 10,000g for 15min at 5C. The supernatant is decanted and filtered through sterile Millipore (0.2m) filter paper to remove all insoluble materials and any remaining bacterial cells.

CFE of a fully grown culture contains different bioreagents such as proteins, polysaccharides along with trace amount of other constituents. Proteins and polysaccharides can be isolated and used as flotation and flocculation reagents.

A suitable volume of a fully grown culture is initially centrifuged, and the supernatant filtered through a sterile millipore (0.2m) filter paper. Analytical reagent grade, extra pure, and fine powdered ammonium sulfate is added slowly to a saturation level of 65% with constant shaking at 4C. The solution is allowed to stay under refrigeration for 12h at 4C. The precipitated protein is dissolved in a minimum volume of 0.1M Tris hydrochloride buffer of pH 7 and dialyzed against the same buffer for over 18h at 4C. The precipitate formed during dialysis is removed through centrifugation and disposed. The clear supernatant is lyophilized, and the resultant solids weighed, and kept at 4C for further use.

An actively grown bacterial culture is harvested by centrifugation and dissolved in lysis buffer (10mM Tris-HCl (pH 8.0), 0.1M NaCl, 1mM EDTA (pH 8.0), 5% (v/v) Triton X-l00). The suspension is sonicated and centrifuged at 10,000g for 5min. The supernatant is subjected to 65% ammonium sulfate precipitation, the solution kept in a refrigerator for 1012h, and centrifuged. The precipitated protein is dialyzed with trisbuffer at neutral pH range and then precipitated with acetone. This protein precipitate is dissolved in trisbuffer and SDS-PAGE is carried out.

A suitable volume of fully grown batch culture is centrifuged to remove bacterial cells. The supernatant containing the extracellular polysaccharide (ECP) is filtered and lyophilized. The dehydrated sample is dissolved in 10mL of distilled water and cooled to <10C. Twenty milliliter of double-distilled ethanol is added to selectively precipitate ECP and purified. It is stored in a refrigerator for 8h at 4C. The precipitate is washed with double-distilled water. The ethanol precipitation procedure is repeated two to three times further, to purify the polysaccharide, and the solution dialyzed with double-distilled water. After dialysis, ECP is stored at low temperature (4C). The concentration of ECP is determined by the phenolsulfuric acid method [40].

The spectrophotometer is switched on and the wavelength adjusted to 280nm. Absorbance is calibrated to zero with buffer and the absorbance of the protein solution measured. The wavelength is adjusted to 260nm and absorbance calibrated to zero with buffer. The absorbance of the protein solution is measured.

One vial with 5mg of BSA is taken and 1mL of distilled water added (5mg/mL), 0.2mL is pipetted out into an Eppendorf tube and 0.8mL of distilled water added (1mg/mL) (Working standard). Standards can be prepared by taking 20, 40, 60, 80, 100L of BSA working standard in test tubes and made to 200L with distilled water. Two mL of Bradford reagent is added to all including test solutions and thoroughly mixed. After 10min, readings are measured at 595nm.

4 % Phenol: Conc. H2SO4, stock standard solution: 100mg of glucose was dissolved in 100mL of double-distilled water (100g/0.1mL). Working standard solution: 10mL of stock solution was made to 100mL with double-distilled water (10g/0.1mL).

Standards are prepared by taking 20, 40, 60, 80, 100L of glucose working standard in test tubes and made to 1mL with double-distilled water. To all the tubes including unknowns, 2mL of 4% phenol and 5mL of concentrated sulfuric acid are added and mixed thoroughly. Readings are taken at 490nm.

Coal is a sedimentary rock that occurs in seams bounded by layers of rock. The generation of waste is unavoidable during coal extraction and beneficiation. Mine waste or spoils are materials that are moved from its in situ location during the mining process but are not processed to obtain the final product. Dealing with mine waste is a major part of surface mining methods, where all of the rock above the coal seam (overburden and sometimes interburden) must be removed to expose the coal seam. This is done in a systematic fashion of digging pits with most of the overburden waste being cast from above the coal to be extracted into an adjacent pit from which the coal has already been extracted. Minimizing the handling of overburden waste is one of the keys to economic success in surface coal mining. Various techniques, such as cast blasting, are used to achieve this objective.

If underground mining methods are used, the amount of out-of-seam material handled is much less than in surface mining, and minimizing that amount has multiple economic benefits as discussed in Chapter 11. When large amounts of out-of-seam material have to be removed for underground infrastructure such as ventilation overcasts and undercasts and conveyor belt transfer points, it can be gobbed or left underground in untraveled mine openings. However, most of the out-of-seam material extracted in underground mines is mixed with the coal and constitutes part of the run-of-mine (ROM) or raw coal product.

Because modern mechanized mining equipment does not distinguish between the coal seam and layers of rock that encapsulate it and because complete or full extraction of a mineable coal seam is generally the objective of any coal-mining operation, there will always be some level of out-of-seam dilution in the ROM product. In most cases, out-of-seam material extracted with the coal must be separated from the coal before shipment to satisfy customer quality requirements. This is accomplished with coal preparation plants that generate a clean coal product and a waste material referred to as coal refuse. Coal preparation plants utilize various mineral processing technologies that, with few exceptions, are slurry-based and involve the use of substantial quantities of water [1]. The efficiency of these processing systems depends on the size of material being treated. Hence, raw coal must be classified into different size fractions leading to two coal refuse products on the output side: (1) coarse coal processing waste (CCPW) and (2) fine coal processing waste (FCPW). Generally, CCPW is material larger than 150m (100 mesh) in size [2]. CCPW includes reject streams from jigs, heavy media vessels, and heavy media cyclones. FCPW includes reject streams from spirals, flotation columns and cells, desliming cyclones, and effluent streams of filter presses, screenbowl centrifuges, and other dewatering equipment. All FCPW streams are typically concentrated in a thickener whose output is a waste slurry.

Most extraction and beneficiation wastes from coal mining (i.e., mine spoils and coal refuse) are categorized as special wastes that are exempted from regulation by hazardous waste rules and laws (e.g., Subtitle C of the US Resource Conservation and Recovery Act). However, coal utilization generates another type of waste known as coal combustion residuals (CCRs), which are regulated to some degree (e.g., Subtitle D of the US Resource Conservation and Recovery Act). CCRs are categorized into four groups based on physical and/or chemical forms that derive from the combustion method and the emission control system used. A brief description of each group follows [3]:

Bottom ash is a coarse, angular, gritty material with similar chemical composition to fly ash. It is too large to be carried up by the smokestack, so it collects in the bottom of the coal furnace. It comprises 12% of all CCRs.

Boiler slag is molten bottom ash that forms into pellets in the bottom of slag tap and cyclone type furnaces. It has a smooth glassy appearance after it is cooled with water. Boiler slag comprises 4% of all CCRs.

Flue gas desulfurization (FGD) material is residue from the sulfur dioxide emission scrubbing process. It can be a wet sludge consisting of calcium sulfite or calcium sulfate, or it can be a dry powdery material that is a mixture of sulfites and sulfates. FGD material comprises 24% of all CCRs.

A simple process of beneficiation has been selected, which will be low in capital cost. As the scheme is a simple one, the cost of operation and maintenance will be minimal. The process technology is so chosen that it should be able to meet the quality parameters laid down by consumers. The flow scheme is briefly described here:

The scheme of beneficiation indicated here is a simple and effective technique that does not take into consideration either small coal or fines. This simple scheme may be applicable both for consumption in the power sector and the cement industry. However, depending upon the raw coal characteristics and needs of the consumer, total washing may be needed, as in the case of coking coal (Fig. 9.6).

Commercial coal cleaning or beneficiation facilities are physical cleaning techniques to reduce the mineral matter and pyretic sulfur content. As a result, the product coal has a higher energy density and less variability (compared with feedstock coal) so that power plant efficiency and reliability are improved. A side benefit to these processes is that emissions of sulfur dioxide and other pollutants including mercury can be reduced. The efficiency of this removal depends on the cleaning process used, the type of coal, and the contaminant content of coal. Basic physical coal cleaning techniques have been commercial for over 50 years. The cleaning of coal takes place in water, in a dense medium, or in a dry medium.

Physical cleaning processes are based on either the specific gravity or the surface property differences between the coal and its impurities. Jigs, concentration tables, hydrocyclones, and froth flotation cells are common devices used in current physical coal cleaning facilities.

The removal efficiency ranged from 0% to 60% with 21% as average reduction. This efficiency is highly dependent on the type of coal and chloride content of the coal. Concerning other fuels, the cleaning of crude oil occurs mostly through the residue desulfurization (RDS). However, the content of Hg in crude oil is usually very low, and RDS is an inefficient method to even lower this content.

minerals | free full-text | review on beneficiation techniques and reagents used for phosphate ores | html

minerals | free full-text | review on beneficiation techniques and reagents used for phosphate ores | html

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guide of mineral processing methods: 3 main beneficiation - jxsc machine

guide of mineral processing methods: 3 main beneficiation - jxsc machine

Physical beneficiation includes magnetic separation, gravity separation, electrostatic beneficiation, friction beneficiation, particle size beneficiation, shape beneficiation, corona beneficiation and manual beneficiation.

Chemical mineral processing includes flotation method (physical and chemical mineral processing is the actual flotation), calcination method, leaching method (bacterial leaching and reagent leaching), mixed mercury method and cyanidation method.

Flotation is a mineral processing method which uses the different physical and chemical properties of mineral surface to separate minerals. Foam flotation is widely used in industry. It is characterized by selectively attaching minerals to the air bubbles in the pulp and then floating up to the surface of the ore slurry to achieve the separation of useful minerals from gangue.

Before flotation, the ore should be grinded to the size required by flotation, so that the useful minerals can basically achieve monomer dissociation for separation. And adding flotation reagent. During flotation, air is introduced into the pulp to form a large number of bubbles. Therefore, particles that are not easily wetted by water(commonly known as hydrophobic minerals), theyare attached to the bubblesandforming a mineralized foam layer along the bubble to the surface of the slurry. The particles that are easily wetted by water(commonly known as hydrophilic minerals), theycannot adhere to the bubbles and remain in the pulp. The purpose of separation is to discharge the mineralized foam.

Direct Flotation & ReverseFlotation In general, the useful minerals are floated into the foam products, leaving gangue minerals in the pulp. This flotation is usually called positive flotation. But sometimes gangue minerals float into foam products, leaving useful minerals in the pulp, which is called reverse flotation.

Preferential Flotation & Mixed Flotation If the ore contains two or more kinds of useful minerals, there are two flotation methods. One is called preferential flotation, the useful minerals are selected into a single concentrate one by one; The other is called mixed flotation, the useful minerals are selected as mixed concentrate at the same time, and then the useful minerals in the mixed concentrate are separated one by one.

Advantages and Disadvantages Flotation method has high separation efficiency. It can effectively separate low-grade ore into high-grade concentrate, especially for the ore with fine-grained distribution and complex composition. When the flotation method is used, it can often achieve good separation effect. But the flotation method must use flotation reagent, so its mineral processing cost is generally higher than gravity separation method and magnetic separation method.

Minerals are divided into strong magnetic minerals, weak magnetic minerals and non-magnetic minerals. Magnetic separation is a mineral separation method in heterogeneous magnetic field according to the difference of mineral magnetism in ore. Magnetic separation is mainly used for magnetic oxide minerals of ferrous minerals, such as magnetite, V-Ti magnetite, hematite and ilmenite, and also for pyrrhotite beneficiation.

Magnetic separation is the concentrationof ilmenite. It uses different permeability of various minerals to make them pass through a magnetic field. Because different minerals react to magnetic field differently, minerals with high permeability are sucked up by disk, and then they fall off. After collecting them through aggregate funnel, the low permeability will not be absorbed, and the belt left in the material or rotating can be separated as tailings.

Gravity separation, also known as gravity dressing. It refers to the mineral processing method that makes use of the difference of relative density, particle size and shape of the separated mineral particles and the difference of movement speed and direction in the medium (water, air or other liquid with relatively high density) to separate them.

Application Compared with other mineral processing methods, gravity separation has the advantages of large processing capacity, wide range of particle size, simple equipment structure, no consumption of valuable production materials, low operation cost and no pollution, so it is widely used in the beneficiation of tungsten and tin ores. It is also widely used in the separation of ferrous metals (iron, manganese, chromium), rare metals (tantalum, niobium, thorium, zirconium, titanium, etc.) and precious metal ores.

Gravity separation is also the main method of coal processing. Gravity separation is also used to separate non-metallic minerals such as pyrite, apatite, diamond and asbestos from coal measures. For those nonferrous metal ores (copper, lead, zinc, etc.) which are mainly treated by flotation, heavy medium mineral processing can also be used to remove coarse gangue or surrounding rock in advance to achieve preliminary enrichment. Classification and dehydration of gravity separation are indispensable in almost all concentrators.

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