Auxiliary processes of mineral processing. Methods and processes of mineral processing, their scope

Preparatory processes for mineral processing

Introduction

Purpose of mineral processing

The extracted rock mass is a mixture of pieces of mineral complexes, intergrowths of minerals with different physical, physicochemical and chemical properties. To obtain final products (concentrates of metals, coke, building materials, chemical fertilizers, etc.), it must be subjected to a number of processing processes: mechanical, thermal, chemical.

The processing of minerals at the concentrator includes a number of operations, as a result of which the separation of useful components from impurities is achieved, those. bringing the mineral to a quality suitable for subsequent processing, for example, it is necessary to increase the content of: iron from 30-50% to 60-70%; manganese from 15-25% to 35-45%, copper from 0.5-1.5% to 45-60%, tungsten from 0.02-0.1% to 60-65%.

According to their purpose, the processes of processing minerals are divided into preparatory, main(enrichment) and support.

Preparatory processes are designed to open or open grains of useful components (minerals) that make up minerals, and dividing them into size classes, meeting the technological requirements of subsequent enrichment processes.

The preparatory processes include crushing, grinding, screening and classification.

Enrichment of minerals is a set of processes of mechanical processing of mineral raw materials, which makes it possible to separate useful minerals (concentrate) from waste rock.

Concentration engineers should solve the following tasks:

Integrated development mineral resources;

Utilization of processed products;

Creation of new processes of non-waste technology for separating minerals into final marketable products for their use in industry;

Environmental protection.

Separation of mixtures of minerals is carried out on the basis of differences in physical, physicochemical and chemical properties with obtaining a number of products with a high content of valuable components (concentrates) , low (intermediate products) and insignificant (waste, tailings) .

The enrichment process is aimed not only at increasing the content of a valuable component in the concentrate, but also at removing harmful impurities:

sulfur in the corner phosphorus in manganese concentrate, arsenic in brown iron ore and sulfide polymetallic ores. These impurities, getting into cast iron and then into steel, worsen the mechanical. metal properties.

Brief information about minerals

minerals called ores, non-metallic and combustible fossil materials used in industrial production in natural or processed form.

TO ores include minerals that contain valuable components in an amount sufficient to make their extraction economically viable.

Ores are classified into metallic and non-metallic.

metal ores - raw materials for the production of ferrous, non-ferrous, rare, precious and other metals - tungsten-molybdenum, lead-zinc, manganese, iron, cobalt, nickel, chromite, gold-containing;

non-metallic ores- asbestos, barite, apatite, phosphorite, graphite, talc, antimony, etc.

Nonmetallic minerals - raw materials for the production of building materials (sand, clay, gravel, building stone, Portland cement, building gypsum, limestone, etc.)

combustible minerals - solid fuel, oil and combustible gas.

Minerals consist of minerals that differ in their value, physical and chemical properties (hardness, density, magnetic permeability, wettability, electrical conductivity, radioactivity, etc.).

Minerals- called native (i.e. occurring in nature in its pure form) elements and natural chemical compounds.

Useful mineral (or component)- they call an element or its natural compound, in order to obtain which the extraction and processing of a mineral is carried out. For example: in iron ore, useful minerals are magnetite Fe 3 O 4, hematite Fe 2 O 3.

Useful impurities- called minerals (elements), the content of which in small quantities leads to an improvement in the quality of products obtained from useful minerals. For example, impurities vanadium, tungsten, manganese, chromium in iron ore positively affect the quality of the metal smelted from it.

Harmful impurities- called minerals (elements), the content of which in small quantities leads to a deterioration in the quality of products obtained from useful minerals. For example, impurities sulfur, phosphorus, arsenic adversely affect the steelmaking process.

Companion elements called the components contained in the mineral in small quantities, released during the enrichment process into individual products or the product of the main component. Further metallurgical or chemical processing of satellite elements allows them to be extracted into a separate product.

Minerals of waste rock- call components that do not have industrial value. In iron ore, these may include SiO 2 , Al 2 O 3 .

Depending on the structure, minerals are distinguished interspersed and solid, for example, in disseminated - individual small grains of a useful mineral are scattered among grains of waste rock; in solid - grains of a useful mineral are represented mainly by a continuous mass, and minerals of waste rock in the form of interlayers, inclusions.

The task of the main enrichment processes is to separate the useful mineral and waste rock. They are based on differences in the physical and physicochemical properties of the separated minerals.

Most often in the practice of enrichment, gravity, flotation and magnetic enrichment methods are used.

2.1. Gravitational enrichment method

Gravitational enrichment method called such, in which the separation of mineral particles, differing in density, size and shape, is due to the difference in the nature and speed of their movement in fluid media under the action of gravity and resistance forces. The gravity method occupies a leading position among other enrichment methods. The gravitational method is represented by a number of processes. They can be actually gravitational (separation in the field of gravity - usually for relatively large particles) and centrifugal (separation in a centrifugal field - for small particles). If separation occurs in air, then the processes are called pneumatic; in other cases - hydraulic. The most widespread in enrichment are actually gravitational processes carried out in water.

According to the type of apparatus used, gravity processes can be divided into jigging, enrichment in heavy media, concentration on tables, enrichment in locks, in chutes, screw separators, enrichment in centrifugal concentrators, counterflow separators, etc. Also, gravitational processes usually include washing.

Gravity processes are used in the enrichment of coal and shale, gold and platinum ores, tin ores, oxidized iron and manganese ores, chromium, wolframite and ores of rare metals, building materials and some other types of raw materials.

The main advantages of the gravitational method are economy and environmental friendliness. Also, the advantages include high productivity, characteristic of most processes. The main drawback is the difficulty of effectively enriching small classes.

Gravity processes are used both independently and in combination with other enrichment methods.

The most common method of gravity enrichment is jigging. jigging is the process of separating mineral particles by density in an aqueous or air medium, pulsating relative to the mixture being separated in the vertical direction.

This method can enrich materials with a particle size of 0.1 to 400 mm. Jigging is used in the enrichment of coal, shale, oxidized iron, manganese, chromite, cassiterite, wolframite and other ores, as well as gold-bearing rocks.

During the jigging process (Fig. 2.1), the material placed on the sieve of the jigging machine is periodically loosened and compacted. In this case, the grains of the enriched material, under the influence of forces acting in a pulsating flow, are redistributed in such a way that particles of maximum density are concentrated in the lower part of the bed, and the minimum density is concentrated in the upper part (the size and shape of the particles also affect the delamination process).

When enriching fine material, an artificial bed of material is placed on the sieve (for example, when coal is enriched, a bed of pegmatite is used), the density of which is greater than the density of a light mineral, but less than the density of a heavy one. the size of the bed is 5-6 times larger than the size of the maximum piece of the original ore and several times larger than the holes in the sieve of the jigging machine. More dense particles pass through the bed and sieve and are unloaded through a special nozzle at the bottom of the jigging machine chamber.

When enriching large material, the bed is not specially laid on the sieve, it is formed by itself from the enriched material and is called natural (the enriched material is larger than the openings of the sieve). Dense particles pass through the bed, move over the sieve and are unloaded through a special unloading slot in the sieve and, further, by the elevator from the machine chamber.

And, finally, when enriching a widely classified material (there are both small and large particles), small dense particles are unloaded through a sieve, large dense particles through an unloading gap (Fig. 2.1).

Currently, about 100 designs of jigging machines are known. Machines can be classified as follows: according to the type of separation medium - hydraulic and pneumatic; according to the method of creating pulsations - piston with a movable sieve, diaphragm, pistonless or air-pulsation (Fig. 2.2). Also, machines can be for the enrichment of small classes, large classes, widely classified material. The most common is hydraulic jigging. And among machines, pistonless ones are most often used.

Piston jigging machines can be used for jigging material with a particle size of 30 + 0 mm. Water vibrations are created by the movement of the piston, the stroke of which is regulated by an eccentric mechanism. Piston jigging machines are not currently produced and have in fact been completely replaced by other types of machines.

Diaphragm jigging machines are used for jigging iron, manganese ores and ores of rare and noble metals with a particle size. Diaphragm jigging machines are used for enrichment of ores with a particle size of 30 to 0.5 (0.1) mm. They are manufactured with various diaphragm arrangements.

Horizontal aperture diaphragm machines usually have two or three chambers. The water oscillations in the chambers are created by the up and down movements of the conical bottoms provided by one or more (depending on the type of machine) eccentric drive mechanisms. The stroke of the conical bottom is controlled by turning the eccentric sleeve relative to the shaft and tightening the nuts, and the frequency of its swings is controlled by changing the pulley on the motor shaft. The body of the machine at each chamber is connected to the conical bottom by rubber cuffs (diaphragms).

Diaphragm jigging machines with a vertical diaphragm have two or four chambers with pyramidal bottoms separated by a vertical partition, in the wall of which a metal diaphragm flexibly connected to it is mounted, making reciprocating movements.

Jigging machines with a movable sieve are used in domestic practice for the enrichment of manganese ores with a particle size of 3 to 40 mm. Machines are not mass-produced. The drive crank mechanism of the sieve is located above the machine body. The sieve makes arcuate movements, in which the material is loosened and moves along the sieve. The machines have two-, three- and four-section sieves with an area of 2.9-4 m 2 . Heavy products are unloaded through the side or central slot. In foreign practice, jigging machines with a movable sieve are used, which make it possible to enrich material with a particle size of up to 400 mm. For example, the Humboldt-Vedag machine makes it possible to enrich material with a particle size of -400 + 30 mm. A distinctive feature of this machine is that one end of the sieve is fixed on the axis and therefore does not move in the vertical direction. The separation products are unloaded by means of an elevator wheel. The car differs in high profitability in work.

Air pulsating (pistonless) jigging machines (Fig. 3.3) differ from others by using compressed air to create water vibrations in the jigging compartment. The machines have an air and jigging compartment and are equipped with a universal drive that provides symmetric and asymmetric jigging cycles and the ability to control the air supply to the chambers. The main advantage of pistonless machines is the ability to control the jigging cycle and achieve high separation accuracy with increased bed height. These machines are used mainly for the enrichment of coal, less often ferrous metal ores. Machines can have side air chambers (Fig. 2.3), under-screen air chambers, branch pipe under-screen air chambers.

With the lateral arrangement of air chambers, the uniformity of water pulsations in the jigging compartment is maintained with a chamber width of no more than 2 m. To ensure a uniform distribution of the pulsating flow velocity field over the area of the jigging sieve, modern designs of jigging machines use hydraulic fairings at the end of the partition between the air and jigging compartments.

Compressed air enters the air compartment periodically through various types of pulsators (rotary, valve, etc.), installed one for each chamber; also periodically the air is released from the air compartment into the atmosphere. When air is admitted, the water level in the air compartment decreases, and in the jigging compartment, of course, it rises (because these are “communicating vessels”); when air is released, the reverse occurs. Due to this, oscillatory movements are made in the jigging compartment.

Enrichment mineral in heavy environments based on the separation of the mineral mixture by density. The process occurs in accordance with the law of Archimedes in media with a density intermediate between the density of a specific light and specific heavy mineral. Specifically light minerals float, and specific heavy ones sink to the bottom of the apparatus. Enrichment in heavy media is widely used as the main process for coals of difficult and medium categories of washability, as well as shale, chromite, manganese, sulfide ores of non-ferrous metals, etc. The separation efficiency in heavy media is higher than the efficiency of enrichment in jigging machines (this is the most efficient gravity process ).

Heavy liquids and heavy suspensions are used as heavy media. There is one fundamental difference between them. A heavy liquid is homogeneous (single-phase), a heavy suspension is inhomogeneous (consists of water and particles suspended in it - a weighting agent). Therefore, enrichment in a heavy liquid is, in principle, acceptable for particles of any size.

A heavy suspension can be considered a pseudo-fluid with a certain density only for sufficiently large (compared to the size of the weighting agent particles) particles. In addition, due to the general movement of the particles of the weighting agent in a certain direction under the influence of the force field in which the enrichment is carried out (gravitational or centrifugal), in order to obtain a suspension of uniform density in the apparatus, it is necessary to mix it. The latter inevitably affects the particles subjected to enrichment. Therefore, the lower limit of particle size, enriched in a heavy suspension, is limited and is: in gravity processes - for ores 2-4 mm, for coals - 4-6 mm; in centrifugal processes for ores - 0.25-0.5 mm, for coals 0.5-1 mm.

As an industrial heavy medium, heavy suspensions are used, i.e. a suspension of fine specific heavy particles (weighting agent) in a medium, which is usually water. (Heavy fluids are not used in industry due to their high cost and toxicity) Hydraulic slurries are simply called slurries. The most commonly used weighting agents are magnetite, ferrosilicon and galena. The particle size of the weighting agent is usually0.15mm. The density of the suspension is determined by the expression:

 c \u003d C ( y - 1) + 1, g / cm 3,

where: C is the concentration of the weighting agent, d.u.,  y is the density of the weighting agent, g / cm 3. Thus, by changing the concentration of the weighting agent, it is possible to prepare a suspension of the required density.

Enrichment in heavy suspensions of medium and large-sized material is carried out in gravity separators (in separators with static separation conditions). Enrichment of fine-grained material is carried out in centrifugal separators (separators with dynamic separation conditions) - hydrocyclones. Other types of heavy media separators (aerosuspension, vibration) are rarely used.

Heavy-medium gravity separators can be divided into three main types - wheel, cone and drum. Wheel separators (Fig. 2.4) are used to enrich material with a particle size of 400-6 mm, in domestic practice mainly for coal and shale. The most commonly used SKV is a wheel separator with a vertical elevator wheel.

In conical suspension separators (Fig. 2.5), the heavy fraction is usually unloaded by an internal or external airlift. These separators are used for beneficiation of ore material with a size of –80(100)+6(2) mm

Cone separators with an external air lift (Fig. 2.5) consist of an upper cylindrical and a lower conical part. The lower conical part ends with a transitional elbow connecting the cone with an air lift that lifts the settled particles. Compressed air is supplied to the air lift pipe through nozzles at a pressure of about 3-4 10 5 Pa. The diameter of the airlift pipe is taken equal to at least three sizes of the largest piece of ore. The floating product, together with the suspension, is drained into the chute, and the heavy product is fed by an airlift into the unloading chamber.

The drum separator (Fig. 2.6) is used for enrichment of ore material with a particle size of 150 + 3 (5) mm, with a high density of the enriched material.

Heavy-medium enrichment hydrocyclones are structurally similar to classifiers. The enriched material is fed tangentially through the feed pipe along with the heavy slurry. Under the action of centrifugal force (many times greater than the force of gravity), the material is stratified: dense particles move closer to the walls of the apparatus and are transported by an “external vortex” to the unloading (sand) nozzle, light particles move closer to the axis of the apparatus and are transported by an “internal vortex” to drain nozzle.

Technological schemes of enrichment in heavy suspensions are practically the same for most operating plants. The process consists of the following operations: preparation of heavy suspension, preparation of ore for separation, separation of ore in suspension into fractions of different density, drainage of the working suspension and washing of separation products, regeneration of the weighting agent.

Enrichment in flows flowing along inclined surfaces is carried out on concentration tables, locks, in chutes and screw separators. The movement of the pulp in these devices occurs along an inclined surface under the action of gravity at a small (compared with the width and length) flow thickness. Usually it exceeds the size of the maximum grain by 2-6 times.

Concentration(enrichment) on the tables- this is the process of separation by density in a thin layer of water flowing along a slightly inclined plane (deck), performing asymmetric reciprocating movements in a horizontal plane perpendicular to the direction of water movement. The concentration on the table is used for the enrichment of small classes - 3 + 0.01 mm for ores and -6 (12) + 0.5 mm for coals. This process is used in the enrichment of ores of tin, tungsten, rare, noble and ferrous metals, etc.; for the enrichment of small classes of coal, mainly for their desulfurization. The concentration table (Fig. 2.7) consists of a deck (plane) with narrow slats (corrugations); support device; drive mechanism. Deck tilt angle  = 410. For light particles, hydrodynamic and lifting turbulent forces are predominant, so light particles are washed away in a direction perpendicular to the deck. Particles of intermediate density fall between heavy and light particles.

Gateway(Fig. 2.8) is an inclined rectangular chute with parallel sides, on the bottom of which trapping coatings (hard stencils or soft mats) are laid, designed to hold settled particles of heavy minerals. Locks are used to enrich gold, platinum, cassiterite from placers and other materials, the enriched components of which vary significantly in density. Gateways are characterized by a high degree of concentration. The material is fed continuously to the sluice until the cells of the stencils are filled predominantly with particles of dense minerals. After that, the loading of the material is stopped and the sluice is rinsed.

jet chute(Figure 2.9) has a flat bottom and sides converging at a certain angle. The pulp is loaded onto the wide upper end of the chute. At the end of the trough, particles of higher density are located in the lower layers, and particles of lower density are located in the upper layers. At the end of the chute, the material is separated by special dividers into concentrate, middlings and tailings. Tapering troughs are used in the enrichment of alluvial ores. Apparatuses such as tapering chutes are divided into two groups: 1) apparatuses consisting of a set of individual chutes in various configurations; 2) conical separators, consisting of one or more cones, each of which is like a set of radially installed tapering chutes with a common bottom.

At screw separators a fixed inclined smooth chute is made in the form of a spiral with a vertical axis (Fig. 2.10), they are used to separate material with a particle size of 0.1 to 3 mm. When moving in a swirling flow, in addition to the usual gravitational and hydrodynamic forces acting on grains, centrifugal forces develop. Heavy minerals are concentrated at the inner side of the trough, while light minerals are concentrated at the outer. Then the separation products are unloaded from the separator using dividers located at the end of the chute.

In centrifugal concentrators the centrifugal force acting on the body is many times greater than the force of gravity and the material is separated by the centrifugal force (gravity has only a small effect). In those cases, if the centrifugal force and gravity are commensurate and separation occurs under the action of both forces, enrichment is usually called centrifugal-gravitational (screw separators).

The creation of a centrifugal field in centrifugal concentrators can in principle be carried out in two ways: tangential supply of a flow under pressure into a closed and stationary cylindrical vessel; by swirling a freely supplied flow in an open rotating vessel and, accordingly, centrifugal concentrators can be fundamentally divided into two types: pressure cyclone apparatus; non-pressure centrifuges.

According to the principle of operation, cyclone-type centrifugal concentrators have much in common with hydrocyclones, but they differ in a significantly larger taper angle (up to 140). Due to this, a “bed” of enriched material is formed in the apparatus, which plays the role of a heavy suspension in heavy-medium enrichment cyclones. And the division is the same. Compared to heavy-medium hydrocyclones, these are much more economical in operation, but they give worse technological performance.

The operation of concentrators of the second type resembles the operation of a conventional centrifuge. Centrifugal concentrators of this type are used to enrich coarse-grained sands, in the exploration of gold-bearing alluvial deposits, and in the extraction of fine free gold from various products. The apparatus is a hemispherical bowl lined with a corrugated rubber insert. The bowl is fixed on a special platform (platform), which receives rotation from an electric motor through a V-belt drive. The pulp of the enriched material is loaded into the apparatus, light particles together with water merge through the sides, heavy ones get stuck in the grooves. To unload the concentrate caught by the corrugated rubber surface, the bowl is stopped and a rinse is performed (there are also designs that allow continuous unloading). When working on coarse gold-bearing sands, the concentrator provides a very high degree of reduction - up to 1000 times or more with high (up to 96-98%) gold recovery.

Countercurrent water separation used in domestic practice for the processing of energy and diluted coals. Apparatus for enrichment by this method are screw and steeply inclined separators. Screw horizontal and vertical are used for enrichment of coal with a particle size of 6 - 25 mm and 13 - 100 mm, as well as for the enrichment of screenings and coarse-grained sludge. Steeply inclined separators are used for enrichment of diluted coals up to 150 mm in size. The advantage of countercurrent separators is the simplicity of the technological scheme. In all counterflow separators, the material is separated into two products: concentrate and waste. The counter transport flows of separation products formed during the separation move within the working area with a given hydraulic resistance to their relative movement, while the flow of light fractions is associated with the flow of the separation medium, and the flow of heavy fractions is counter. The working zones of the separators are closed channels, equipped with a system of the same type of elements, streamlined by the flow and causing the formation of a system of secondary flows and vortices organized in a certain way. As a rule, in such systems, the source material is separated at a density that is much higher than the density of the separating medium.

A necessary condition for the preparation of sands of alluvial deposits and ores of sedimentary origin for enrichment is their release from clay. The mineral particles in these ores and sands are not bound by mutual intergrowth, but are cemented into a dense mass by a soft and viscous clay substance.

The process of disintegration (loosening, dispersion) of clay material, cementing grains of sand or ore, with its simultaneous separation from ore particles with the help of water and the corresponding mechanisms is called flushing. Disintegration usually occurs in water. At the same time, clay swells in water, and this facilitates its destruction. As a result of washing, washed material (ore or sand) and sludge containing fine-grained clay particles dispersed in water are obtained. Washing is widely used in the enrichment of ferrous metal ores (iron, manganese), sands of placer deposits of rare and precious metals, building materials, kaolin raw materials, phosphorites and other minerals. Washing can be of independent importance if it results in a marketable product. More often it is used as a preparatory operation to prepare the material for subsequent enrichment. For washing, they use: screens, butars, scrubbers, scrubber-butars, trough washes, vibro-washers and other devices.

Pneumatic processes beneficiation is based on the principle of separating minerals by size (pneumatic classification) and density (pneumatic concentration) in an ascending or pulsating air stream. It is used in the enrichment of coal, asbestos and other minerals with low density; in the classification of phosphorites, iron ores, minium and other minerals in the cycles of crushing and dry grinding, as well as in the dedusting of air flows in the shops of concentrating factories. The use of the pneumatic enrichment method is expedient in severe climatic conditions northern and eastern regions of Siberia or in areas where there is a lack of water, as well as for the processing of minerals containing easily soaked rock that forms a large number of slimes that violate the clarity of separation. The advantages of pneumatic processes are in their efficiency, simplicity and convenience of tailings disposal, the main disadvantage is in the relatively low separation efficiency, which is why these processes are used very rarely.

LECTURE COURSE

Introduction. The value and role of enrichment when using various PIs…6

Classification of enrichment processes………………………………………..14

Types and schemes of enrichment and their applications…………………………………….21

Screening processes. Designs and principle of operation of screens…………..27

Methods and processes for crushing minerals……………………...38

Types of crushers and crushing schemes……………………………………………….45

Grinding process. Types and principle of operation of mills…………………….58

Product classification…………………………………………………………70

The design and principle of operation of hydraulic classifiers. The design and principle of operation of air classifiers………………74

Gravitational enrichment methods…………………………………………….82

Enrichment in heavy media………………………………………………….89

Enrichment on jigging machines……………………………………….....99

Enrichment on concentration tables…………………………………..110

Flotation enrichment methods. Types of flotation reagents and their use in production……………………………………………………..118

Designs and principle of operation of flotation machines…………………….127

Magnetic enrichment methods……………………………………………………………………137

Electrical enrichment. Dehydration of enrichment products……..145

The use of various thickeners and the principle of their operation. Mechanical equipment for filtering……………………………………………..154

List of Recommended Sources……………………………………………168

DOING. SIGNIFICANCE AND ROLE OF ENRICHMENT DURING THE USE OF VARIOUS MINERAL RESOURCES.

Purpose: Getting students initial skills in terms and names, as well as in the meaning of the subject itself and its value in practical application.

Plan:

1.
Basic terms of the subject and their meaning.

2.
General information about ores and minerals of non-ferrous and rare metals.

Subdivisions and grouping of ores.

3.
Characteristics of the Deposits. Concentrates, middlings, tailings.

4.
The value and role of processing plants in the use of minerals.

Key words: ore, mineral, monometallic ore, polymetallic, useful component, valuable component, concentrate, intermediate product, tailings, waste rock, oxidized ores, native, finely disseminated, sulfide, mineral processing, processing plant, value (social, economic).

1. “The main directions of the economic and social development of the Republic of Uzbekistan for the modern period provide for further improvement of the technology for mining and processing ores and concentrates, increasing the complexity of the use of mineral raw materials, accelerating the introduction of efficient technological processes, improving the quality and range of products.

The development of the country's economic stability is the development of modern technologies and techniques of various industries, including mineral processing.

The source of obtaining metals, many types of raw materials, fuels, as well as building materials are minerals.

Minerals depending on the nature and purpose of valuable components, it is customary to subdivide into: ore, non-metallic and combustible.

Ores called minerals that contain valuable components in an amount sufficient to be extracted with state of the art technology and technique was cost-effective. Ores are divided into metallic and non-metallic.

to metal include ores that are raw materials for the production of ferrous, non-ferrous, rare, precious and other metals.

to non-metallic - asbestos, barite, apatite, phosphorite, graphite, talc and others.

To nonmetallic includes raw materials for the production of building materials (sand, clay, gravel, building stone, cement raw materials, and others).

to fuel include fossil fuels, oil and natural gas.

valuable components individual chemical elements or minerals that are part of a mineral and are of interest for their further use are called.

Useful impurities they call individual chemical elements or their natural compounds that are part of a mineral in small quantities and can be isolated and used together with the main valuable component, improving its quality. For example: beneficial impurities in iron ores are chromium, tungsten, vanadium, manganese and others.

Related components called valuable chemical elements and individual minerals contained in minerals in relatively small quantities, released during enrichment along the way into an independent or complex product together with the main valuable component, and extracted from it later in the process of metallurgical smelting or chemical processing . For example: in some ores of non-ferrous metals, gold, silver, molybdenum and others are associated.

Harmful impurities are called individual impurities and elements, or natural chemical compounds contained in minerals and having a negative impact in minerals on the quality of the extracted valuable components.

2. The composition of the ore is simple (the useful component is represented by one mineral) and complex (the useful component is represented by minerals of various properties).

Minerals that do not contain valuable components are called empty rock. During enrichment, they are removed to waste (tails) together with harmful impurities.

As a result of enrichment, the main constituent components of a mineral can be isolated in the form of independent products: concentrates (one or more) and tails. In addition, in the process of enrichment, intermediate products can also be separated from the mineral.

Sources of extraction of non-ferrous and rare metals are deposits of ores or minerals containing one or more valuable metals (components) represented by the corresponding minerals in combination with the host rock. In very rare cases, native elements (copper, gold, silver) are found in the earth's crust in the form of grains having a crystalline or amorphous structure. The content of gold and silver in the ore is very low, only a few grams per 1 ton of ore. For 1 g of gold in the earth's crust, there are about 2 tons of rock.

Ore - this is a breed from which at this stage of the development of technology it is economically profitable to extract valuable components. The ore is composed of individual minerals; those that need to be extracted are called valuable (useful), and those that are not used in this case are minerals of the host (empty) rock.

However, the concept "blank breed" conditionally. With the development of beneficiation techniques and methods for the subsequent processing of products obtained during beneficiation, the gangue minerals contained in the ore become useful. So, in apatite-nepheline ore, nepheline long time was a waste rock mineral, but after the technology for producing alumina from nepheline concentrates was developed, it became a useful component.

According to the mineral composition, ores are divided into native, sulfide, oxidized and mixed.

Ores are also divided into monometallic And polymetallic.

Monometallic ores contain only one valuable metal. Polymetallic - two or more, for example, Xi, Pb, Zn, Fe, etc. In nature, polymetallic ores are much more common than monometallic ores. Most ores contain several metals, but not all of them are of industrial importance. In connection with the development of enrichment technology, it becomes possible to extract those metals, the content of which in the ore is low, but their associated extraction is economically feasible.

There are also ores interspersed And solid. In disseminated ores, grains of valuable minerals are distributed in the mass of the host rock. Solid ores (pyrite) consist of 50 ... 100% sulfides, mainly pyrite (sulfur pyrite) and a small amount of minerals of the host rock.

According to the size of disseminated grains of useful minerals, ores are coarsely disseminated (> 2 mm), finely disseminated (0.2 ... 2 mm), finely disseminated (< 0,2 мм) и весьма тонковкрапленные (< 0,02 мм). Последние являются труднообогатимыми рудами.

Deposits of industrial ores by nature of origin are indigenous And placer. Primary deposits occur in the place of initial formation. Valuable minerals and minerals of the host rock in these ores are in close association with each other.

Placers are called secondary deposits formed as a result of the destruction of primary primary deposits and the secondary deposition of material from primary ores. Placer deposits contain non-sulfide, sparingly soluble minerals in the form of rounded (rolled) grains. There are no intergrowths, which facilitates and reduces the cost of the process of enrichment of placers.

The earth's crust contains about 4 thousand different minerals, which are more or less stable natural chemical compounds. Some of them, such as quartz, feldspars, aluminosilicates, pyrite, make up the bulk of the earth's crust, others, for example, the minerals Cu, Pb, Zn, Mo, Be, Sn are found in large quantities only in certain areas - ore bodies, others, such as germanite (germanium mineral), greenockite (cadmium mineral) are even rarer, accompanying various minerals in ores.

Sulfide minerals are minerals that are compounds of metals with sulfur. For example, chalcopyrite CuFe$2 is the main mineral of copper, sphalerite 2n8 - zinc, molybdenite MoS 2 - molybdenum.

Oxides include a significant part of non-ferrous and rare-metal minerals, for example, cuprite Cu 2 O, ilmenite FeTiO 3, rutile TiO 2, cassiterite SnO 2.

Silicates are the largest group of minerals found in the earth's crust. In the upper mantle of the earth, they make up to 92%. The silicates include the bulk of the minerals of the host (waste) rock (unsuitable for industrial consumption), as well as the minerals of lithium, beryllium, zircon, etc. Among the silicates, quartz SiO 2 is most common; it can be extracted into an independent product and used in the production of glass, crystal, in the construction industry.

The aluminosilicates include spodumene LiAlSi 2 O b and beryl Be 3 Al 6 O 18 , which are the main minerals in the production of 1 lithium and beryllium, as well as spar, albite NaAlSizO 8 and microcline KAlSi 3 O 8 , the main minerals of the host rock (on average 60%.

Carbonates include minerals containing carbon dioxide: calcite CaCO3 (a host rock mineral), cerussite PbCO 3 .

3. Deposits of industrial ores by the nature of origin are primary and alluvial. Indigenous ores are called, occurring in the place of initial formation and located inside the general rock massif. These ores after extraction from a mine or from an open pit require preliminary crushing and grinding before enrichment. Valuable minerals and gangue minerals in such ores are in close association with each other.

Placers are called secondary deposits formed as a result of the destruction of ores of primary primary deposits and the secondary deposition of material from primary ores. In placers, minerals have undergone very strong changes in chemical composition and physical properties. All minerals and large pieces of ore were destroyed by water flows, weathering, temperature changes, chemical compounds, etc.

River water flows or waves of the sea and ocean usually carry pieces of ore and minerals over long distances. Rolling, they take a rounded shape. At the same time, sulfides are destroyed and are completely absent in the deposits, and non-sulfide, sparingly soluble minerals are freed from intergrowths with minerals of waste rock (sand, pebbles). Therefore, the ores of alluvial deposits are not subjected to crushing and grinding, and their enrichment processes are much simpler and cheaper.

With the help of enrichment, harmful impurities are removed from concentrates entering the metallurgical plant, which impede the smelting processes and degrade the quality of the metals obtained. Removal of harmful impurities can significantly improve the technical and economic performance of metallurgical processes. For example, a harmful impurity in lead concentrate is zinc. Increasing its content in lead concentrate from 10 to 20% increases the loss of lead during melting by almost 2 times. In the process of ore beneficiation, concentrates (one or several), tailings and intermediate products are obtained.

concentrates - products in which the main amount of one or another valuable component is concentrated. Concentrates, in comparison with enriched ore, are characterized by a significantly higher content of useful components and a lower content of waste rock and harmful impurities.

middlings - products obtained during the enrichment of minerals and representing a mixture of grains containing useful components with grains of waste rock. Intermediate products are characterized by a lower content of useful components compared to concentrates and a higher content of useful components compared to tailings.

Tails - products that contain the main amount of waste rock, harmful impurities and a small (residual) amount useful component.

Enrichment of minerals is a set of processes for the primary processing of mineral raw materials from the bowels, as a result of which the separation of useful components (minerals) from waste rock occurs.

Concentrates and tailings are final products, while intermediate products are circulating. The quality of concentrates issued by processing plants must meet the requirements determined by GOSTs or technical conditions. These requirements depend on the purpose of the concentrates and the conditions for their further processing. GOSTs indicate the lowest permissible content of a useful component and the highest permissible content of harmful impurities for concentrates of various grades.

The enrichment results are evaluated by several indicators and, above all, by the completeness of the extraction of valuable components and the quality of the resulting concentrates.

Extraction is the ratio of the amount of a useful component converted into a concentrate to its amount in the ore, expressed as a percentage. Extraction characterizes the completeness of the transfer of a useful component from ore to concentrate and is one of the most important technological indicators of the processing plant.

The output is the ratio of the mass of any enrichment product to the mass of processed ore, expressed as a percentage.

Enrichment of ores is a set of processes for the primary processing of mineral raw materials, with the aim of separating all useful minerals (and, if necessary, their mutual separation) from waste rock. As a result of enrichment, one or more rich concentrates and tailings are obtained. The concentrate contains dozens, sometimes hundreds of times more useful mineral than ore. It is suitable for metallurgical processing or can serve as a raw material for other industries. Dump tailings contain mainly waste rock minerals, which, under the given technical and economic conditions, are not expedient to extract or there is no need for these minerals.

The need for mineral processing processes is confirmed by the dependence of the technical and economic indicators of metallurgical processing on the metal content in the raw materials entering the smelting.

An even greater economic effect is obtained by enriching poor ores containing rare and other expensive metals (molybdenum, tin, tantalum, niobium, etc.).

The importance of mineral processing is determined by the fact that:

firstly, in many cases, only after it many technological processes (metallurgical, chemical, and others) become possible;

secondly, the processing of the enriched product is carried out with a greater economic effect than the natural one: the volume of processed material is reduced, the quality of the finished product is improved, the loss of a valuable component with production waste and the cost of transporting raw materials are reduced, labor productivity is increased, fuel and electricity costs are reduced, etc. d.

Mineral processing technology consists of a series of sequential operations carried out at processing plants.

processing plants called industrial enterprises where minerals are processed by enrichment methods and one or more commercial products with a high content of valuable components and a low content of harmful impurities are isolated from them. A modern concentrating plant is a highly mechanized enterprise with a complex technological scheme for processing minerals.

Technology system includes information on the sequence of technological operations for the processing of minerals at the processing plant.

Conclusions:

The source of extraction of non-ferrous and rare metals are deposits of ores or minerals containing one or more non-ferrous or rare metals, represented by the corresponding minerals in combination with minerals of gangue.

In very rare cases, native elements (copper, gold, silver and sulfur) are found in the earth's crust. Usually they form various chemical compounds - minerals, which are natural products of processes occurring in the earth's crust. Native elements occur mainly in the solid state and are grains having a crystalline or amorphous structure.

Minerals are natural mineral substances that, at a given level and state of technology, can be used with sufficient efficiency in the national economy in natural form or after pretreatment.

Fossils mined from the bowels of the earth are solid (ore, coal, peat), liquid (oil) and gaseous (natural gases).

According to the material composition, metallic minerals are divided into ores of ferrous, non-ferrous, rare, noble and radioactive metals.

According to the mineral composition, ores are divided into native, sulfide, oxidized and mixed.

From ores of non-ferrous and rare metals, which usually contain a very small percentage of a useful mineral, it is economically unprofitable, and often practically impossible, to smelt metal without preliminary enrichment. Therefore, more than 95% of mined ores are enriched.

Test questions:

1.
What are the categories of minerals?

2.
What is an ore and what ores are classified as metallic, non-metallic, non-metallic, combustible?

3.
What are called valuable components, useful impurities, related components, harmful impurities?

4.
The main value of mineral processing and processing plants.

5. What components are ores divided into?

6. Simple and complex ores.

What is called concentrate, middlings and tailings?

What is mineral processing?

How are deposits characterized?

What are the main indicators of the economic benefits of mineral processing?

Homework :

1.
Prepare for a survey on a given lecture topic.

2.
Prepare a short thesis on the topic of the seminar assignment.

3.
Answer questions for the lecture.

CLASSIFICATION OF ENRICHMENT PROCESSES.

Purpose: Knowledge short description enrichment processes, for students' primary perception of the subject.

Plan:

1.
General information on the classification of enrichment processes.

2.
a brief description of main enrichment processes.

3.
Brief description of special enrichment methods.

4.
Technological indicators of enrichment

Key words: basic processes, special, screening; splitting up; grinding; classification, gravitational enrichment processes; flotation methods; magnetic enrichment methods; electrical beneficiation, manual and mechanized mining, sample processing, decripitation, radiometric beneficiation methods.

Enrichment of minerals is a very important aspect in the extraction and processing of ores. It is divided into many enrichment methods, which implies the highest quality and complete enrichment process.

Preparatory processes are intended to prepare the ore for beneficiation. The preparation includes, first of all, the operations of reducing the size of ore pieces - crushing and grinding and the associated classification of ore on screens, in classifiers and hydrocyclones. The final fineness of grinding is determined by the fineness of disseminated minerals, since when grinding it is necessary to open the grains of valuable minerals as much as possible.

The actual enrichment processes include the processes of separating ore and other products according to the physical and physico-chemical properties of the minerals that make up their composition. These processes include gravity separation, flotation, magnetic and electrical separation, etc.

Most enrichment processes are carried out in water and the resulting products contain a large amount of it. Therefore, there is a need for auxiliary processes. These include dehydration of enrichment products, including thickening, filtering and drying.

The totality and sequence of operations that ore undergoes during processing constitute enrichment schemes, which are usually depicted graphically. Depending on the purpose, schemes can be qualitative, quantitative, sludge. In addition to these schemes, circuit diagrams of apparatuses are usually drawn up.

Thus, mineral processing can be divided into main and auxiliary enrichment processes (methods).

The main enrichment methods include:

1.screening; 2.crushing; 3.grinding; 4.classification; 5. gravity enrichment processes; 6.flotation methods; 7. magnetic enrichment methods; electrical enrichment.

Helper methods include:

1. manual and mechanized mining and washing. Selective crushing and decripitation;

2.enrichment in friction, shape and elasticity;

3.radiometric methods of enrichment;

4. chemical enrichment methods.

2Screening called the process of separating lumpy and granular materials into products of various sizes, called classes, using screening surfaces with calibrated holes (grate, sheet and wire sieves).

As a result of screening, the source material is divided into an oversize (upper) product, the grains (pieces) of which are larger than the size of the holes of the screening surface, and an undersize (lower product), the grains (pieces) of which are smaller than the size of the holes of the screening surface.

Crushing and grinding - the process of destruction of minerals under the action of external forces to a given size, the required particle size distribution or the required degree of opening of materials. During crushing and grinding, overgrinding of materials should not be allowed, as this worsens the process of mineral processing.

Classification - the process of separating a mixture of mineral grains into classes of different sizes according to their settling rates in water or air. Classification is carried out in special devices called classifiers, if the separation occurs in aquatic environment(hydroclassification), and air separators if the separation takes place in air.

Gravity processes enrichment refers to enrichment processes in which the separation of mineral particles that differ in density, size or shape is due to the difference in the nature and speed of their movement in the medium under the action of gravity and resistance forces.

Gravity processes include jigging, enrichment in heavy media, concentration on tables, enrichment in locks, chutes, jet concentrators, cone, screw and countercurrent separators, pneumatic enrichment.

Flotation enrichment methods - the process of separating finely divided minerals, carried out in an aquatic environment and based on the difference in their ability, natural or artificially created, to be wetted by water, which determines the selective adhesion of mineral particles to the interface between two phases. Big role during flotation, flotation reagents play - substances that allow the process to proceed without any special complications and accelerate the flotation process itself, as well as the concentrate yield.

Magnetic enrichment methods minerals are based on the difference in the magnetic properties of the separated minerals. Separation according to magnetic properties is carried out in magnetic fields.

In magnetic enrichment, only inhomogeneous magnetic fields are used. Such fields are created by the appropriate shape and arrangement of the poles of the separator's magnetic system. Thus, magnetic enrichment is carried out in special magnetic separators.

Electrical enrichment called the process of separating minerals in an electric field, based on the difference in their electrical properties. These properties are electrical conductivity, dielectric constant, triboelectric effect.

3.Manual mining and rock sampling as a way of enrichment based on the use of differences in external signs separable minerals - color, luster, grain shape. From the total mass of a mineral, the material that contains less is usually selected. In the case when a valuable component is taken from a mineral, the operation is called mining, when the waste rock is called mining.

Decripitation is based on the ability of individual minerals to crack (destroy) when they are heated and then rapidly cooled.

Enrichment in friction, shape and resilience is based on the use of differences in the velocities of the particles being separated along the plane under the action of gravity. The main parameter of the movement of particles along an inclined plane is the coefficient of friction, which depends mainly on the nature of the surface of the particles themselves and their shape.

Adiometric sorting , based on the difference in the radioactive properties of minerals or the strength of their radiation

Radiometric enrichment methods are based on the different ability of minerals to emit, reflect, or absorb different types of radiation.

To chemical enrichment methods include processes associated with the chemical transformations of minerals (or only their surfaces) into other chemical compounds, as a result of which their properties change, or with the transfer of minerals from one state to another.

Chemical and bacterial enrichment based on the ability of minerals, such as sulfides, to oxidize and dissolve in highly acidic solutions. In this case, the metals pass into solution, from which they are extracted by various chemical and metallurgical methods. The presence in solutions of certain types of bacteria, such as thionic ones, significantly intensifies the process of mineral dissolution.

IN technological schemes enrichment of complex complex ores, two or three different enrichment methods are often used simultaneously, for example: gravity and flotation, gravity and magnetic, etc. Combined enrichment methods are also used in combination with hydrometallurgical ones.

For the successful application of one or another enrichment method, it is necessary that the minerals have a sufficient difference in the properties that are used in this method.

4. The beneficiation process is characterized by the following technological indicators: metal content in the ore or beneficiation product; product output; degree of reduction and extraction of metal.

Metal content in ore or enrichment product - this is the ratio of the mass of this metal in the ore or enrichment product to the mass of dry ore or product, expressed as a percentage. The metal content is usually denoted by the Greek letters α (in the original ore), β (in the concentrate) and θ (in the tails). The content of precious metals is usually expressed in units of mass (g/t).

Product yield - the ratio of the mass of the product obtained - during enrichment, to the mass of the processed initial ore, expressed in fractions of a unit or percent. Concentrate yield (γ) indicates what proportion of the total ore is concentrate.

Degree of reduction - a value indicating how many times the yield of the resulting concentrate is less than the amount of processed ore. Degree of reduction (TO) expresses the number of tons; ore that needs to be processed to get 1 ton of concentrate, and is calculated by the formula:

K= 100/γ

Ores of non-ferrous and rare metals are characterized by a low yield of concentrate and, consequently, a high degree of reduction. The yield of the concentrate is determined by direct weighing or according to chemical analysis according to the formula:

γ =(α - θ/β - θ)100,%.

The degree of enrichment, or the degree of concentration, shows how many times the metal content in the concentrate has increased compared to the metal content in the ore. When enriching poor ores, this indicator can be 1000 ... 10000.

Metal recoveryε is the ratio of the mass of metal in the concentrate to the mass of metal in the original ore, expressed as a percentage

ε=γβ/α

Metal balance equation

εα=γβ

connects the main technological indicators of the process and allows you to calculate the degree of extraction of the metal into the concentrate, which, in turn, shows the completeness of the transition of the metal from the ore to the concentrate.

The yield of enrichment products can be determined from the data of chemical analyzes of the products. If we designate: - concentrate output; - metal content in ore; - metal content in the concentrate; - metal content in tailings, and - extraction of metal into concentrate, then it is possible to draw up a balance of metal for ore and enrichment products, i.e. the amount of metal in the ore is equal to the sum of its amounts in the concentrate and tailings

Here, 100 is taken to be the percentage yield of the original ore. Hence the output of the concentrate

Extraction of metal into concentrate can be calculated by the formula

If the concentrate yield is unknown, then

For example, when enriching lead ore containing 2.5% lead, a concentrate containing 55% lead and tailings containing 0.25% lead were obtained. Substituting the results of chemical analyzes in the above formulas, we get:

concentrate output

extraction to concentrate

tailings output

degree of enrichment:

Qualitative and quantitative indicators of enrichment characterize the technical perfection of the technological process at the factory.

The quality of the final enrichment products must meet the requirements set by consumers for their chemical composition. Requirements for the quality of concentrates are called standards and are regulated by GOST, specifications(TU) or temporary standards and are developed taking into account the technology and economics of the processing of this raw material and its properties. Conditions establish the minimum or maximum allowable content of various constituent components of a mineral in the final products of enrichment. If the quality of the products meets the standards, then these products are called standard.

Conclusions:

The processing plant is an intermediate link between the mine (mine) and the metallurgical plant. Ore of various sizes coming from the mine, during processing at the concentrating plant, undergoes various processes, which, according to their purpose, can be divided into preparatory, concentrating and auxiliary ones.

The material composition of minerals.

The material composition of minerals is a set of data on the content of useful components and impurities, mineral forms of manifestation and the nature of the intergrowth of grains of the most important elements, their crystal chemical and physical properties.

Chemical composition

The chemical composition of minerals characterizes the content of the main and associated minerals, as well as useful and harmful impurities.

A useful component is contained in the p.i. in industrial concentrations, determining their main value, purpose and name. For example iron in iron ores.

Associated useful components are the constituent parts of p.i. the extraction of which is economically feasible only in conjunction with the main p.c. for example, gold and silver in semi-metallic sulfide ores.

Useful impurities are called valuable elements contained in the SP, which can be isolated and used in conjunction with the main SP, improving its quality. For example. Chromium and tungsten in iron ores, etc.

Harmful impurities are called elements present in the p.i. together with the main useful component and worsening its qualities. For example, sulfur and phosphorus in iron ores, sulfur in coals.

Chemical composition of p.i. determined by spectral, chemical assay, nuclear physics, activation and other types of analysis.

Mineralogical composition.

The mineralogical composition characterizes the mineral forms of manifestation of the elements that make up minerals.

In accordance with the mineral forms of manifestation of the main valuable components of non-ferrous metal ores, non-ferrous metal ores are distinguished as sulfide, oxidized, mixed.

Iron ores: magnetite, titanomagnetite, hematite-martite, brown ironstone, siderite.

Manganese ores: brownite, psilomelanovad, pyrolusite, mixed complex.

Mining and chemical raw materials: apatite, apatite - nepheline, phosphorite, sylvinite ores.

1.1.3. Textural and structural characteristics.

Textural and structural features in the structure of a mineral are characterized by size, shape, spatial distribution of mineral inclusions and aggregates.

The main forms of mineral grains are idiomorphic (limited by the edges of the crystal), allotriomorphic (limited by the shape of the space to be filled), colloidal, emulsion, lamellar - relic-residual, fragments and fragments.

Depending on the prevailing size of mineral excretions, there are large (20-2 mm), small (2-0.2 mm), thin (0.2-0.02 mm), very thin or emulsion (0.02-0.002 mm) , submicroscopic (0.002-0.0002 mm) and colloid-dispersed (less than 0.0002 mm) dissemination of minerals.

The texture of the ore characterizes the mutual arrangement of mineral aggregates and can be very diverse. For example, in banded and layered structures, the aggregates are adjacent to each other; in nodules - are located one inside the other; in looped - mutually penetrate each other; in cockades, they successively border others with some mineral aggregates.

Characteristics of mineral deposits is the basis for the development of technology and forecasting indicators of mineral processing.

The larger the dissemination of minerals and the more perfect the form of their segregations, the simpler the technology and the higher the mineral enrichment rates.

Physical properties

Each ore mineral has a specific chemical composition and has a characteristic structure. This causes fairly constant and individual physical properties of minerals: color; density; electrical conductivity; magnetic susceptibility, etc.

By creating in a certain way the conditions under which certain properties of minerals are most contrasting, it is possible to separate them from each other, including separating valuable minerals from the total mass. .",. ,

As signs of the separation of mineral components during mineral processing, their physical and chemical properties are used, the most important of which are: mechanical strength; density; magnetic permeability; electrical conductivity and dielectric constant; various types of radiation; wettability; solubility, etc.

The mechanical strength (strength) of ores and coals is characterized by crushability, brittleness, hardness, abrasiveness, temporary compressive strength and determines the energy costs during their crushing and grinding, as well as the choice of crushing-grinding and enrichment equipment.

The nuclear-physical properties of minerals are manifested when they interact with electromagnetic radiation(luminescence, photoelectric effect, Compton effect, fluorescence, etc.).

The separation of minerals is based on the difference in the intensity of the emission or attenuation of radiation by them.

The magnetic properties of minerals arise and manifest themselves in a magnetic field. The measure of evaluation of the magnetic properties of minerals is their magnetic permeability and the associated magnetic susceptibility, equal to 1/|1m. Magnetic properties are determined mainly by the chemical composition and partly by the structure of minerals. Increased magnetic susceptibility is characteristic of minerals, which include iron, nickel, manganese, chromium, vanadium, titanium.

Coal matter is diamagnetic, and mineral impurities in it are paramagnetic.

Differences in the magnetic properties of minerals are used to separate them using magnetic enrichment methods.

The electrical properties of minerals are determined by electrical conductivity and dielectric constant.

Differences in the electrical properties of minerals are used to separate them using electrical enrichment methods.

Wetting is a manifestation of intermolecular interaction at the boundary of contact between phases - a solid, liquid and gas, which is expressed in the spreading of a liquid over the surface of a solid.

Differences in the wettability of the surface of finely divided mineral particles are used for their separation by flotation enrichment methods.

Solubility of minerals - the ability of minerals to dissolve in inorganic and organic solvents. The transfer of the solid phase to the liquid state can be carried out by dissolution as a result of diffusion and intermolecular interaction or due to chemical reactions.

The real solubility of solids is determined empirically. Differences in the solubility of mineral components are used in chemical methods of ore dressing.

The characteristics of the material compositions are shown in Figure 1.

Fig 1. Characteristics of the material composition.

Classification of methods and processes of enrichment.

At the processing plants p.i. are subjected to a series of sequential processing processes, which, according to their purpose, are divided into:

preparatory

Main enrichment

Auxiliary and production service processes

preparatory processes. Preparatory processes include crushing and grinding, in which the disclosure of minerals is achieved as a result of the destruction of intergrowths of useful minerals with waste rock (or intergrowths of some useful minerals with others) with the formation of a mechanical mixture of particles and pieces of different mineral composition, as well as processes screening and classification, used for size separation of mechanical mixtures obtained during crushing and grinding. The task of the preparatory processes is to bring the mineral raw materials to the size required for subsequent enrichment, and in some cases, to obtain the final blow of a given particle size distribution for direct use in the national economy (sorting ores and coals).

Enrichment of minerals- a set of processes for the primary processing of mineral raw materials, which has as its goal the separation of all valuable minerals from waste rock, as well as the mutual separation of valuable minerals.

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general information

During enrichment, it is possible to obtain both final commercial products (asbestos, graphite, etc.) and concentrates suitable for further chemical or metallurgical processing. Enrichment is the most important intermediate link between the extraction of minerals and the use of extracted substances. The theory of enrichment is based on the analysis of the properties of minerals and their interaction in separation processes - minerallurgy.

Enrichment allows you to significantly increase the concentration of valuable components. The content of important non-ferrous metals - copper, lead, zinc - in ores is 0.3-2%, and in their concentrates - 20-70%. The concentration of molybdenum increases from 0.1-0.05% to 47-50%, tungsten - from 0.1-0.2% to 45-65%, the ash content of coal decreases from 25-35% to 2-15%. The task of enrichment also includes the removal of harmful impurities of minerals (arsenic, sulfur, silicon, etc.). The extraction of valuable components into the concentrate in the enrichment processes ranges from 60 to 95%.

The processing operations to which the rock mass is subjected at the concentrating factory are divided into: main (actually concentrating); preparatory and auxiliary.

All existing enrichment methods are based on differences in the physical or physico-chemical properties of individual components of a mineral. There are, for example, gravitational, magnetic, electrical, flotation, bacterial and other methods of enrichment.

Technological effect of enrichment

Preliminary enrichment of minerals allows:

to increase the industrial reserves of mineral raw materials through the use of deposits of poor minerals with a low content of useful components;
increase labor productivity at mining enterprises and reduce the cost of mined ore due to the mechanization of mining operations and the continuous extraction of minerals instead of selective;
to improve the technical and economic indicators of metallurgical and chemical enterprises in the processing of enriched raw materials by reducing the cost of fuel, electricity, fluxes, chemical reagents, improving the quality of finished products and reducing the loss of useful components with waste;
to carry out the complex use of 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;
isolate harmful impurities from mineral raw materials, which, during their further processing, can degrade the quality of the final product, pollute environment and endanger human health.

Processing of minerals is carried out at concentrating factories, which today are powerful highly mechanized enterprises with complex technological processes.

Classification of enrichment processes

The processing of minerals at processing plants includes a series of sequential operations, as a result of which the separation of useful components from impurities is achieved. According to their purpose, the processes of processing minerals are divided into preparatory, main (concentrating) 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 meet the technological requirements of 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 (minerals) under the action of external mechanical, thermal, electrical forces aimed at overcoming the internal cohesive forces that bind the particles of a solid body together.

According to the physics of the process, there is no fundamental difference between crushing and grinding. Conventionally, it is considered that when crushing, particles larger than 5 mm are obtained, and when crushed, particles are smaller than 5 mm. The size of the largest grains, to which it is necessary to crush or grind the mineral in its preparation 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 it is supposed to carry out the next operation of processing the crushed (crushed) product.

Opening grains of useful components - crushing and (and) grinding of intergrowths until the grains of a useful component are completely released and a mechanical mixture of grains of a useful component and waste rock (mix) is obtained. Opening grains of useful components - crushing and (and) grinding of intergrowths until part of the surface of the useful component is released, which provides access to the reagent.

Crushing is carried out on special crushing plants. Crushing is the process of destruction of solids with a decrease in the size of the pieces to a given fineness, by the action of external forces that overcome the internal cohesive forces that bind the particles of the solid.

Screening and classification

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

Screening is carried out by special machines - screens.

The classification of the material by size is carried out in an aqueous or air environment and is based on the use of differences in the settling rates of particles of different sizes. Large particles settle faster and concentrate in the lower part of the classifier, small particles settle more slowly and are carried out of the apparatus by water or air flow. The large products obtained during the classification are called sands, and the small ones are called a drain (for hydraulic classification) or a thin product (for pneumoclassification). Classification is used to separate small and thin products by grain sizes no larger than 1 mm.

Basic (enrichment) processes

The main enrichment processes are designed to isolate one or more useful components from the original mineral raw materials. The feedstock is separated during the beneficiation process into the appropriate products - concentrate(s), industrial products and final tailings. In enrichment processes, the differences between the minerals of the useful component and the 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 enrichment of minerals by the gravitational method. It is widely used in the enrichment of coal, ores and non-metallic raw materials.

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 electrical separation method. Such minerals include apatite, tungsten, tin and other ores.

Enrichment by fineness is used in cases where useful components are represented by larger or, conversely, smaller grains compared to waste rock grains. In placers, useful components are in the form of small particles, so the separation of large classes allows you to get rid of a significant part of rock impurities.

Differences in grain shape and friction coefficient make it possible to separate flat scaly particles of mica or fibrous aggregates of asbestos 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 rounded 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 the components are used in the enrichment of minerals by the method of photometric separation. This method is used to mechanically separate grains of different colors and luster (for example, separating diamond grains from waste rock grains).

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

For dehydration of enrichment products, methods of drainage (screens, elevators), centrifugation (filtering, settling and combined centrifuges), thickening (thickeners, hydrocyclones), filtration (vacuum filters, filter presses) and thermal drying are used.

In addition to technological processes, for the normal functioning of the processing plant, production service processes should be provided: intrashop transport of minerals and products of their processing, supply of the factory with water, electricity, heat, technological quality control of raw materials and processed products.

The main methods of mineral processing

According to the type of environment in which enrichment is carried out, enrichment is distinguished:

dry enrichment (in air and aerosuspension),
wet (in water, heavy media),
in the field of centrifugal forces,

Gravitational enrichment methods are based on the difference in density, size and speed of movement of rock pieces in an aqueous or air environment. When separating in heavy media, the difference in the density of the separated components is of primary importance.

To enrich the smallest particles, the flotation method is used, based on the difference in the surface properties of the components (selective wettability with water, adhesion of mineral particles to air bubbles).

Mineral processing products

As a result of enrichment, the mineral is divided into several products: concentrate (one or more) and waste. In addition, intermediate products can be obtained during the enrichment process.

concentrates

Concentrates are enrichment products in which the main amount of a valuable component is concentrated. Concentrates, in comparison with enriched material, are characterized by a significantly higher content of useful components and a lower content of waste rock and harmful impurities.

Waste

Waste - products with a low content of valuable components, the further extraction of which is technically impossible or economically inexpedient. (This term is equivalent to the previously used term tailings, but not the term tails, which, unlike waste, are present in almost every enrichment operation)

Intermediates

Intermediate products (middle products) are a mechanical mixture of intergrowths with open grains of useful components and waste rock. Intermediate products are characterized by a lower content of useful components in comparison with concentrates and a higher content of useful components in comparison with waste.

Enrichment quality

The quality of minerals and beneficiation products is determined by the content of a valuable component, impurities, accompanying elements, as well as moisture content and fineness.

Mineral processing is ideal

Under the ideal enrichment of minerals (ideal separation) is understood the process of separation of the mineral mixture into components, in which there is no clogging of each product with particles foreign to it. The efficiency of ideal mineral processing is 100% by any criteria.

Partial mineral processing

Partial enrichment is the enrichment of a separate class of mineral size, or the separation of the most easily separated part of contaminating impurities from the final product in order to increase the concentration of a useful component in it. Used, for example, to reduce