The rock mass is divided into: basic (actually enrichment); preparatory and auxiliary.

All existing methods enrichments are based on differences in physical or physical chemical properties Oh individual components mineral. There are, for example, gravitational, magnetic, electric, flotation, bacterial and other enrichment methods.

Technological effect of enrichment

Preliminary enrichment of minerals allows:

• increase industrial reserves of mineral raw materials through the use of deposits of poor mineral resources with a low content of useful components;
• increase labor productivity at mining enterprises and reduce the cost of mined ore through mechanization of mining operations and continuous mining of minerals instead of selective ones;
• increase the technical and economic indicators of metallurgical and chemical enterprises when processing enriched raw materials by reducing the costs of fuel, electricity, fluxes, chemical reagents, and improving quality finished products and reducing losses of useful components with waste;
• implement complex use minerals, because preliminary enrichment makes it possible to extract from them not only the main useful components, but also accompanying ones, which are contained in small quantities;
• reduce the cost of transporting mining products to consumers by transporting richer products, and not the entire volume of mined rock mass containing minerals;
• extract from mineral raw materials harmful impurities, which, during further processing, can deteriorate the quality of the final product, pollute the environment and threaten human health.

Mineral processing is carried out at processing factories, which today are powerful, highly mechanized enterprises with complex technological processes.

Classification of enrichment processes

Processing of minerals at processing plants includes a number of sequential operations, as a result of which the separation of useful components from impurities is achieved. According to their purpose, mineral processing processes are divided into preparatory, main (concentration) and auxiliary (final).

Preparatory processes

Preparatory processes are designed to open or open the grains of useful components (minerals) that make up the mineral, and divide it into size classes that satisfy technological requirements subsequent enrichment processes. The preparatory processes include crushing, grinding, screening and classification.

Crushing and grinding

Crushing and grinding- the process of destruction and reduction in the size of pieces of mineral raw materials (mineral resources) under the influence of external mechanical, thermal, electrical forces aimed at overcoming the internal adhesion forces that connect particles of a solid body to each other.

According to the physics of the process, there is no fundamental difference between crushing and grinding. It is conventionally accepted that crushing produces particles larger than 5 mm, and grinding produces particles smaller than 5 mm. The size of the largest grains to which it is necessary to crush or grind a mineral when preparing it for enrichment depends on the size of the inclusions of the main components that make up the mineral and on technical capabilities equipment on which the next operation of processing the crushed (crushed) product is supposed to be carried out.

Opening of grains of useful components - crushing and/or grinding of splices until complete liberation grains of a useful component and obtaining a mechanical mixture of grains of a useful component and waste rock (mixed). Opening grains of useful components - crushing and/or grinding of aggregates until part of the surface of the useful component is released, which provides access to the reagent.

Crushing is carried out in special crushing plants. Crushing is the process of destruction solids with a reduction in the size of pieces to a given size, through the action of external forces overcoming the internal adhesion forces connecting the particles together solid. Grinding of crushed material is carried out in special mills (usually ball or rod).

Screening and classification

Screening and classification are used to separate minerals into products of different sizes - size classes. Screening is carried out by dispersing minerals on sieves and sieves with calibrated holes into small (under-sieve) product and large (over-sieve). Screening is used to separate minerals by size on screening (screening) surfaces, with hole sizes ranging from a millimeter to several hundred millimeters.

Screening is carried out by special machines - screens.

Minerals, the components of which have differences in electrical conductivity or have the ability, under the influence of certain factors, to acquire electrical charges of different magnitude and sign, can be enriched by the method of electrical separation. Such minerals include apatite, tungsten, tin and other ores.

Enrichment by size is used in cases where useful components are represented by larger or, conversely, smaller grains in comparison with grains of waste rock. In placers, useful components are found in the form of small particles, so the separation of large classes makes it possible to get rid of a significant part of rock impurities.

Differences in grain shape and coefficient of friction make it possible to separate flat, scaly mica particles or fibrous asbestos aggregates from rock particles that have a rounded shape. When moving along an inclined plane, fibrous and flat particles slide, and rounded grains roll down. The rolling friction coefficient is always less than the sliding friction coefficient, therefore flat and round particles move along an inclined plane with at different speeds and along different trajectories, which creates conditions for their separation.

Differences in the optical properties of components are used in the beneficiation of minerals by photometric separation. This method carries out mechanical separation of grains having different colour and shine (for example, separating diamond grains from gangue grains).

The main final operations are pulp thickening, dewatering and drying of enrichment products. The choice of dehydration method depends on the characteristics of the material being dehydrated (initial moisture content, particle size and mineralogical composition) and the requirements for final moisture content. Often the required final moisture content is difficult to achieve in one stage, so in practice dehydration operations are used for some enrichment products different ways in several stages.

Waste

Waste is the final enrichment product with a low content of valuable components, the further extraction of which is technically impossible and/or economically impractical. (This term is equivalent to the previously used term dump tailings, but not the term tails, which, in contrast to waste, is the depleted product of any single enrichment operation).

Intermediates

Intermediate products (middlings) are a mechanical mixture of aggregates with open grains of useful components and waste rock. Industrial products are characterized by a lower content of useful components compared to concentrates and a higher content of useful components compared to waste.

Enrichment quality

The quality of minerals and enrichment products is determined by the content and extraction of valuable components, impurities, accompanying elements, as well as moisture and particle size.

Mineral beneficiation is ideal

Ideal enrichment of minerals (ideal separation) refers to the process of separating a mineral mixture into components, in which there is absolutely no contamination of each product with particles foreign to it. The efficiency of ideal mineral processing is 100% by any criteria.

Partial beneficiation of minerals

Partial enrichment is the enrichment of a separate size class of a mineral, or the separation of the most easily separated part of clogging impurities from the final product in order to increase the concentration of the useful component in it. It is used, for example, to reduce the ash content of unclassified thermal coal by isolating and enriching the large class with further mixing of the resulting concentrate and fine unenriched screenings.

Losses of minerals during beneficiation

The loss of a mineral during enrichment refers to the amount of a useful component suitable for enrichment that is lost with enrichment waste due to imperfections in the process or a violation of the technological regime.

Installed acceptable standards mutual contamination of enrichment products for different technological processes, in particular, for coal enrichment. The permissible percentage of mineral losses is reset from the balance of enrichment products to cover discrepancies when taking into account the mass of moisture, the removal of minerals with flue gases from drying plants, and mechanical losses.

Mineral beneficiation boundary

The mineral beneficiation limit is the smallest and largest dimensions particles of ore and coal, effectively enriched in a concentration machine.

Enrichment depth

The enrichment depth is the lower limit of the size of the material to be enriched.

When enriching coal, technological schemes with enrichment limits of 13 are used; 6; 1; 0.5 and 0 mm. Accordingly, unenriched screenings with a particle size of 0-13 or 0-6 mm, or sludge with a particle size of 0-1 or 0-0.5 mm, are separated. An enrichment limit of 0 mm means that all size classes are subject to enrichment.

International congresses

Since 1952, International Congresses on Mineral Processing have been held. Below is a list of them.

Congress	Year	Location
I	1952	London
II	1953	Paris
III	1954	Goslar
IV	1955	Stockholm
V	1960	London
VI	1963	Kahn
VII	1964	NY
VIII	1968	Leningrad
IX	1970	Prague
X	1973	London
XI	1975	Cagliari
XII	1975	Sao Paulo
XIII	1979	Warsaw
XIV	1982	Toronto
XV	1985	Kahn
XVI	1988	Stockholm
XVII	1991	Dresden
XVIII	1993	Sydney
XIX	1995

Ore beneficiation is based on the use of differences in physical and physical and chemical properties minerals, on the amount of dissemination of valuable minerals.

The physical properties of minerals are color, luster, density, magnetic susceptibility, electrical conductivity, and wettability of the mineral surface.

There are various enrichment methods.

The gravity enrichment method is based on the use of differences in densities, sizes and shapes of minerals. This method is used for gold, tin, tungsten, placers, rare metals, iron, manganese, chromium, coal, phosphorites, diamonds.

Separation of minerals by density can be carried out in water, air and heavy media. Gravitational processes include:

Enrichment in heavy environments – used for ores with coarse inclusions of 100-2 mm;

Jigging - based on the difference in the speed of falling particles in a vertical stream of water, used for coarsely disseminated ores 25-5 mm;

Enrichment on concentration tables - associated with the separation of minerals under the influence of forces resulting from the movement of the table and the flow of water flowing along the inclined plane of the table, used for ores with a particle size of 3-0.040 mm;

Enrichment on sluices - the separation of minerals occurs under the influence of a horizontal flow of water and the capture of heavy minerals by covering the bottom of the sluices, used for ores with a particle size of 300-0.1 mm;

Enrichment using screw, jet and cone separators - separation occurs under the influence of a flow of water moving along an inclined plane for ores with a particle size of 16-1 mm.

The magnetic enrichment method is based on the separation of minerals due to the difference between minerals in specific magnetic susceptibility and the difference in the trajectories of their movement in a magnetic field.

The flotation enrichment method is based on the difference in the wettability of individual minerals and, as a result, their selective adhesion to air bubbles. This is a universal beneficiation method, used for all ores, especially polymetallic ones. The size of the enriched material is 50-100% class -0.074 mm.

Electrostatic beneficiation is based on differences in the electrical conductivity of minerals.

In addition, there are special enrichment methods, which include:

Decripitation is based on the ability of minerals to crack along cleavage planes upon strong heating and strong cooling;

Ore sorting by color, gloss, can be manual, mechanical, automated; usually used for large material >25 mm;

Radiometric sorting , based on the different abilities of minerals to emit, reflect and absorb certain rays;

Friction enrichment is based on differences in friction coefficients;

Chemical and bacterial enrichment is based on the properties of minerals (for example, sulfides) to oxidize and dissolve in highly acidic solutions. The metal dissolves and is then extracted using chemical-hydrometallurgical methods. The presence of certain types of bacteria in solutions intensifies the process of dissolution of minerals.

2.3 Enrichment operations and processes

The processing plant is an intermediate link between the mine and the metallurgical plant. An enrichment plant is a complex combination of all kinds of machines and apparatus. The capacity of the factory is usually determined by the amount of processed ore and varies from 15 thousand tons to 50 million tons per year. Large factories are located in several buildings.

Ore of various sizes (D max = 1500-2000 mm - typical for open-pit mining, D max = 500-600 mm - typical for underground mining), coming from the mine to the processing plant, undergoes various processes, which, according to their purpose, can be divided into :

Preparatory;

Actually enrichment;

Auxiliary.

Preparatory processes include, first of all, operations of reducing the size of ore pieces: crushing, grinding and the associated classification of ore on screens, classifiers and hydrocyclones. The final grinding size is determined by the dissemination size of the minerals.

The beneficiation processes themselves include the processes of separating ore and other products according to the physical and physico-chemical properties of the minerals included in their composition. These processes include gravity concentration, flotation, magnetic and electrical separation and other processes.

Most enrichment processes are carried out in water, so at a certain stage there is a need to reduce or remove it, which can be done using auxiliary processes. Auxiliary processes include dehydration operations: thickening, filtration, drying.

The set and sequence of operations to which ore is subjected during processing constitute enrichment schemes, which are usually depicted graphically. There are schemes:

Fundamental (Fig. 2.2);

Qualitative (if data on the quantity and quality of products is not provided) (Fig. 2.3);

Qualitative-quantitative;

Water-sludge;

Circuit diagrams of devices (Fig. 2.4).

Rice. 2.2 Schematic diagram of enrichment (reflects only the main features of the technology)	Rice. 2.3 Qualitative enrichment scheme (the qualitative diagram shows operations, enrichment products and their path along the diagram)	Rice. 2.4 Device circuit diagram 1 – source ore bunker; 2, 5, 8, 10 and 11 – conveyors; 3 and 6 – screens; 4 – jaw crusher; 7 – cone crusher; 9 – crushed ore bunker; 12 – mill;

13 – spiral classifier; 14 – flotation machine; 15 – thickener;

16 – vacuum filter; 17 – drying drum.

Mineral beneficiation is a set of technological processes for pre-processing mineral raw materials in order to give it qualities that meet consumer requirements.

When enriched:

The content of useful components in raw materials increases,

Harmful impurities are removed from raw materials,

Uniformity of raw materials in size and composition is achieved.

As a result of enrichment we get:

Concentrate is a beneficiation product that has a higher content of useful components compared to ore. In terms of its content, the content of impurities, moisture, concentrates must meet the requirements of GOSTs, OSTs, TUs;

Waste tailings are enrichment waste consisting of waste rock with an insignificant content of useful components, the extraction of which is technologically impossible or economically unprofitable.

10 3 10 2 10 -1

Enrichment reduces the cost of transporting raw materials, as well as processing them, because A large volume of waste rock is removed.

The figure shows the dependence of the specific energy consumption during crushing and grinding of medium-strength material on various final sizes.

The degree of crushing (grinding) is the ratio of the diameter of the largest pieces of ore (D) to the diameter of the pieces of the crushed product (d):

Depending on the properties of the ore, the following is used:

1 – crushing – destruction as a result of compression of pieces between two pressing bodies;

2 – splitting – destruction as a result of wedging between the tips of crushing bodies;

3 – impact – destruction under the influence of short-term dynamic loads;

4 – abrasion – destruction as a result of the influence of surfaces moving relative to each other.

Depending on the method and mechanism of destruction of ore pieces, there are:

Jaw crushers (they crush and split pieces between periodically approaching plates - jaws) are periodic devices: ore crushing alternates with an unloading-loading cycle, which is the main disadvantage of this type of crushers, which reduces their productivity;

Cone crushers (crush and abrade pieces between moving and stationary cones) – crushers continuous action;

Roller crushers (they crush and split pieces between two smooth or toothed shafts moving towards each other) - continuous crushers;

Impact crushers are used to crush soft and tough materials.

The material is crushed in mills various types:

Drum mills are used to grind material to a particle size of 1-2 mm. This is a steel drum into which grinding media are loaded along with ore. Depending on the type of crushing bodies, ball, rod, pebble and self-grinding mills are distinguished.

After each stage of crushing (grinding), the fine fraction is separated from the resulting product using screening (sifting). Screening is usually used to separate materials with particle sizes greater than 1-2 mm.

Hydraulic classification methods are used to separate materials with particle sizes less than 100 microns. Hydraulic classification is the process of separating a mixture of mineral grains by size based on differences in the rates of their sedimentation in water.

Then comes the actual enrichment. The most common enrichment methods are:

Flotation,

Gravitational,

Magnetic,

Electric.

By using flotation More than 90% of all ores of ferrous and non-ferrous metals are enriched, as well as non-metallic minerals: sulfur, graphite, phosphate ores, coal.

The flotation system is heterogeneous and includes three phases: solid, liquid, gas. Flotation is based on the ability of solid particles to be retained at the interface between the liquid and gas phases, i.e. on hydrophobicity and non-wetting of particles. The most common is froth flotation. Mineral grains that are not wetted by water stick to air bubbles and float to the surface. By changing the flotation conditions, you can achieve, for example, the following: during flotation iron ores magnetite (iron ore concentrate) will be released into the foam product - direct flotation, and quartz (waste rock) may be released - reverse flotation, i.e. Flotation processes are universal due to the variety of operating methods and wide control possibilities.

To carry out the flotation process it is necessary to use various chemical compounds:

Collectors – sharply increase the hydrophobicity of the surface of the extracted particles. When flotation of sulfide materials is used

Xanthates R-O-C-S-Me and dithiophosphates RO S

(R – alcohol or phenol radical; Me – Na or K);

Non-sulfide minerals float with Na-soaps of fatty acids (Na oleate – C17H33COONa) or amines (RNH2);

Coal, sulfur and other naturally hydrophobic minerals are floated using kerosene and other non-polar reagents.

Foaming agents - substances that facilitate air dispersion, prevent the merging of bubbles and increase the strength of the foam (various surfactants, pine oil);

Environmental regulators - create an optimal pH of the environment (lime, soda, sulfuric acid).

The flotation process is carried out in flotation machines. The foam product is fed for dehydration.

Gravitational processes are based on the difference in the nature and speed of movement of mineral particles with different densities in a water or air environment:

Washing is the separation by loosening and removing with the help of water clay materials that bind the grains of minerals (iron and manganese ores, phosphorites, placers of non-ferrous, rare and noble metals, washing gold sand, high quality building material);

Enrichment in harsh environments– separation of extracted minerals by density. The resulting products (heavy and light fractions) have a density greater or less than the density of the separating medium and, because of this, either float or sink in it. Such enrichment is the main one in the coal industry. Organic liquids, aqueous solutions of salts and suspensions are used as heavy media:

Organic liquids: trichloroethane C2H3C13 (density 1460 kg/m3), chloroform CC14 (1600), dibromoethane C2H4Br2 (2170), acetylenetetrabromide C2H1Br2 (2930);

Aqueous solutions of inorganic salts: CaСd2 (1654), ZnС12 (2070);

Suspensions: crushed to less than 0.1 mm are used as weighting agents. various substances– clay (1490), pyrite (2500), galena PbS (3300). When enriching coal, a magnetite suspension (2500) is used.

Magnetic enrichment used in the processing of ores of ferrous, rare and non-ferrous metals. It is based on the use of differences in magnetic properties minerals and waste rock. When particles move through a magnetic field, the magnetic and non-magnetic products move along different trajectories. According to specific magnetic susceptibility, minerals are divided into:

Highly magnetic - magnetite Fe 3 O 4, pyrrhotite Fe 1-n S n - χ >380*10 -7 m3/kg,

Weakly magnetic – hydroxides and carbonates of Fe and Mn - χ = (7.5-1.2)* 10-7 m3/kg,

Non-magnetic quartz SiO2, apatite Ca5(F,Cl)(PO4)3, rutile TiO2, feldspar (Na,K,Ca)(AlSi3O8).

Electrical enrichment based on the different electrical conductivity of rocks and their properties to electrify. Electrical separation is used to enrich granular bulk solids with a particle size of 0.05-3 mm, the components of which do not have significant differences in other properties (density, magnetic susceptibility, physical and chemical properties of the surface).

Depending on the specific electrical conductivity, minerals are divided into:

Conductors – rutile, pyrite,

Semiconductors – magnetite,

Non-conductors – quartz, zircon (ZrSO4).

When particles of a conductor mineral come into contact with an electrode, they become charged with the same charge. The dielectric particle is not charged. The particles then pass through a constant electric field and change their trajectories depending on the charge on their surface.

Processing plants– a source of significant emissions of dust and wastewater.

Dust formation occurs during the processing and storage of solid mineral raw materials. Strong dust emission is observed during dry crushing, screening, dry enrichment methods, transportation and reloading of enrichment products.

When crushers operate, the main dust emission occurs in the areas where the product is unloaded and reaches 4 g/s for roller crushers, 10 g/s for cone and jaw crushers, and 120 g/s for hammer crushers. When mills operate, up to 80 g/s of dust is released.

Wastewater is discharged into tailings ponds along with enrichment tailings, from where it can flow into water bodies.

The main pollutants are coarse impurities (gravity tailings), dissolved salts, flotation reagents in the form of emulsions, products of interaction of reagents with each other and with minerals.

Wastewater may contain:

Acids used in the technological process

Ions Fe, Cu, Ni, Zn, Pb, Al, Co, Cd, Sb, Hg and others that fall into wastewater due to the dissolution of their compounds by acids,

Cyanide is the main pollutant in gold mining factories and factories that use cyanide melt as a flotation reagent,

Fluorides, if the flotation reagents are NaF, NaSiF6,

Petroleum products, most often kerosene, flotation agent in the enrichment of coal, sulfur, Cu-Mo, Mo-W oreB

Phenols, like flotation agents, xanthates and dithiophosphates are flotation agents with an unpleasant odor.

Basic (enrichment) processes

Basic (concentration) processes are designed to separate the initial mineral raw materials with opened or exposed grains of the useful component into the corresponding products. As a result of the main processes, useful components are isolated in the form of concentrates, and rock minerals are removed in the form of waste, which is sent to a dump. In enrichment processes, the differences between minerals of the useful component and waste rock in density, magnetic susceptibility, wettability, electrical conductivity, size, grain shape, chemical properties, etc. are used.

Differences in the density of mineral grains are used in the beneficiation of minerals using the gravity method. It is widely used in the beneficiation of coal, ores and non-metallic raw materials.

Magnetic enrichment of minerals is based on unequal impact magnetic field on mineral particles with different magnetic susceptibility and on the action of coeric force. Iron, manganese, titanium, tungsten and other ores are enriched using the magnetic method, using magnetic separators. In addition, this method is used to isolate ferrous impurities from graphite, talc and other minerals and use them for the regeneration of magnetite suspensions.

Differences in the wettability of components with water are used in the enrichment of minerals by flotation. A special feature of the flotation method is the ability to individually regulate wetness and separate very fine mineral grains. Thanks to these features, the flotation method is one of the most universal; it is used for the enrichment of a variety of finely disseminated minerals.

Differences in the wettability of components are also used in a number of special processes for the beneficiation of hydrophobic minerals - in oil agglomeration, oil granulation, polymer (latex) and oil flocculation.

Minerals whose components have differences in electrical conductivity or have the ability, under the influence of certain factors, to acquire different values ​​and signs electric charges, can be enriched by electrical separation. Such minerals include apatite, tungsten, tin and other ores.

Enrichment by size is used in cases where useful components are represented by larger or, conversely, smaller grains in comparison with grains of waste rock. In placers, useful components are found in the form of small particles, so the separation of large classes makes it possible to get rid of a significant part of rock impurities.

Differences in the shape of the grains and the coefficient of friction make it possible to separate flat, scaly mica particles or fibrous asbestos aggregates from rock particles that have a rounded shape. When moving along an inclined plane, fibrous and flat particles slide, and rounded grains roll down. The rolling friction coefficient is always less than the sliding friction coefficient, so flat and round particles move along an inclined plane at different speeds and along different trajectories, which creates conditions for their separation.

Differences in the optical properties of components are used in the enrichment of minerals by photometric separation. This method is used to mechanically separate ore grains that have different colors and luster (for example, separating diamond grains from waste rock grains).

The differences in the adhesive and sorption properties of minerals of the useful component and waste rock underlie the adhesive and sorption methods of gold enrichment and adhesive enrichment of diamonds (methods belong to special enrichment methods).

The different properties of mineral components to interact with chemical reagents, bacteria and (or) their metabolites determine the operating principle of chemical and bacterial leaching of a number of minerals (gold, copper, nickel).

Different solubilities of minerals underlie modern complex (combined) processes such as “extraction and enrichment” (borehole dissolution of salts with further evaporation of the solution).

The use of one or another enrichment method depends on mineral composition minerals, physical and chemical properties of the separated components.

When looking at commercially valuable minerals, the question rightly arises as to how such an attractive piece of jewelry can be made from primary ore or fossil. Especially considering the fact that rock processing as such represents, if not one of the final, then at least a process of refining that precedes the final stage. The answer to the question will be enrichment, during which basic processing of the rock occurs, involving the separation of valuable minerals from empty media.

General enrichment technology

Processing of valuable minerals is carried out at special enrichment plants. The process involves performing several operations, including preparation, direct splitting and separation of rock with impurities. During enrichment, various minerals are obtained, including graphite, asbestos, tungsten, ore materials, etc. These do not necessarily have to be valuable rocks - there are many factories that process raw materials, which are later used in construction. One way or another, the basics of mineral processing are based on an analysis of the properties of minerals, which also determine the principles of separation. By the way, the need to cut off different structures arises not only for the purpose of obtaining one pure mineral. It is a common practice for several valuable breeds to be bred from one structure.

Rock crushing

At this stage, the material is crushed into individual particles. The crushing process involves mechanical forces, with the help of which the internal clutch mechanisms are overcome.

As a result, the rock is divided into small solid particles that have a homogeneous structure. It is worth distinguishing between direct crushing and grinding techniques. In the first case, the mineral raw material undergoes a less deep separation of the structure, during which particles with a fraction of more than 5 mm are formed. In turn, grinding ensures the formation of elements with a diameter of less than 5 mm, although this indicator depends on what kind of rock you are dealing with. In both cases, the goal is to maximize grain splitting useful substance so that a pure component is released without a mix, that is, waste rock, impurities, etc.

Screening process

After completion of the crushing process, the harvested raw materials are subjected to another technological impact, which can be either sieving or weathering. Screening is essentially a method of classifying the resulting grains according to their size characteristics. Traditional way The implementation of this stage involves the use of a sieve and a sieve, provided with the ability to calibrate the cells. During the screening process, over-grid and under-grid particles are separated. In some way, the enrichment of minerals begins at this stage, since some of the impurities and mixes are separated. Small fractions less than 1 mm in size are screened out using air environment- weathering. The mass, reminiscent of fine sand, is lifted by artificial air currents and then settles.

Subsequently, particles that settle more slowly are separated from very small dust elements that linger in the air. For further collection of the derivatives of such screening, water is used.

Enrichment processes

The enrichment process aims to separate mineral particles from the feedstock. During such procedures, several groups of elements are isolated - useful concentrate, waste tailings and other products. The principle of separating these particles is based on the differences between the properties of useful minerals and waste rock. Such properties can be the following: density, wettability, magnetic susceptibility, size, electrical conductivity, shape, etc. Thus, enrichment processes that use differences in density use gravitational separation methods. This approach is used for ore and non-metallic raw materials. Enrichment based on the wettability characteristics of the components is also very common. In this case, the flotation method is used, a feature of which is the ability to separate fine grains.

Magnetic enrichment of minerals is also used, which makes it possible to separate ferrous impurities from talc and graphite media, as well as to purify tungsten, titanium, iron and other ores. This technique is based on the difference in the effect of a magnetic field on fossil particles. The equipment used is special separators, which are also used for the recovery of magnetite suspensions.

Final stages of enrichment

The main processes of this stage include dehydration, pulp thickening and drying of the resulting particles. The selection of equipment for dehydration is based on the chemical and physical characteristics of the mineral. Usually, this procedure performed in several sessions. However, the need for its implementation does not always arise. For example, if electrical separation was used in the enrichment process, then dewatering is not required. In addition to preparing the enrichment product for further processes processing, an appropriate infrastructure must be provided for handling mineral particles. In particular, the factory organizes appropriate production services. Intra-shop vehicles, the supply of water, heat and electricity is organized.

Beneficiation equipment

At the grinding and crushing stages, special installations are used. These are mechanical units that, with the help of various driving forces, have a destructive effect on the rock. Next, in the screening process, a sieve and sieve are used, in which the possibility of calibrating the holes is provided. More complex machines called screens are also used for sifting. Direct enrichment is carried out by electric, gravitational and magnetic separators, which are used in accordance with the specific principle of structure separation. After this, drainage technologies are used for dewatering, in the implementation of which the same screens, elevators, centrifuges and filtration devices can be used. The final stage, as a rule, involves the use of funds heat treatment and drying.

Waste from the enrichment process

As a result of the enrichment process, several categories of products are formed, which can be divided into two types - useful concentrate and waste. Moreover, a valuable substance does not necessarily have to represent the same rock. It also cannot be said that waste is unnecessary material. Such products may contain valuable concentrate, but in minimal quantities. At the same time, further enrichment of minerals that are in the waste structure is often not technologically and financially justified, so secondary processes of such processing are rarely carried out.

Optimal enrichment

Depending on the enrichment conditions, the characteristics of the starting material and the method itself, the quality of the final product may vary. The higher the content of valuable components and the fewer impurities in it, the better. Ideal ore beneficiation, for example, involves complete absence waste in the product. This means that in the process of enriching the mixture obtained by crushing and screening, from total mass debris particles from waste rocks were completely eliminated. However, it is not always possible to achieve such an effect.

Partial beneficiation of minerals

Partial enrichment refers to the separation of the size class of the fossil or the cutting off of an easily separated part of the impurities from the product. That is, this procedure does not aim to completely clean the product from impurities and waste, but only increases the value of the source material by increasing the concentration of useful particles. Such processing of mineral raw materials can be used, for example, to reduce the ash content of coal. During the enrichment process, a large class of elements is isolated upon further mixing of the concentrate of unenriched screenings with the fine fraction.

The problem of loss of valuable rock during enrichment

Just as unnecessary impurities remain in the mass of the useful concentrate, the valuable rock can be removed along with the waste. To account for such losses, we use special means, allowing you to calculate permissible level these for each of the technological processes. That is, individual standards for acceptable losses are developed for all separation methods. The acceptable percentage is taken into account in the balance of processed products in order to cover discrepancies in the calculation of the moisture coefficient and mechanical losses. Such accounting is especially important if ore beneficiation is planned, during which deep crushing is used. Accordingly, the risk of losing valuable concentrate increases. And yet, in most cases, the loss of useful rock occurs due to violations in the technological process.

Conclusion

Behind Lately technologies for the enrichment of valuable rocks have taken a noticeable step in their development. Both individual processing processes and general separation schemes are being improved. One of the promising directions for further advancement is the use of combined processing schemes that improve the quality characteristics of concentrates. In particular, magnetic separators are combined, resulting in an optimized enrichment process. New techniques of this type include magnetohydrodynamic and magnetohydrostatic separation. At the same time, there is also a general tendency for the deterioration of ore rocks, which cannot but affect the quality of the resulting product. An increase in the level of impurities can be combated by the active use of partial enrichment, but in general, an increase in processing sessions makes the technology ineffective.