Extraction of tungsten from the tailings of processing plants. Extraction of weakly magnetic minerals on a high-intensity magnetic separator from ores of non-ferrous, rare earth and noble metals on the example of Irgiredmet OJSC, Kovdorsky GOK. World tungsten market

Magnetic methods are widely used in the enrichment of ores of ferrous, non-ferrous and rare metals and in other areas of industry, including food. They are used for beneficiation of iron, manganese, copper-nickel tungsten ores, as well as for finishing concentrates of rare metal ores, regeneration of ferromagnetic weighting agents in separation plants in heavy suspensions, for removing iron impurities from quartz sands, pyrite from coal, etc.

All minerals are different in specific magnetic susceptibility, and in order to extract weakly magnetic minerals, fields with high magnetic characteristics are required in the working zone of the separator.

In ores of rare metals, in particular tungsten and niobium and tantalum, the main minerals in the form of wolframite and columbite-tantalite have magnetic properties and it is possible to use high-gradient magnetic separation with extraction of ore minerals into the magnetic fraction.

In the laboratory of magnetic enrichment methods NPO ERGA, tests were carried out on tungsten and niobium-tantalum ore of the Spoykoininsky and Orlovsky deposits. For dry magnetic separation, a roller separator SMVI manufactured by NPO ERGA was used.

The separation of tungsten and niobium-tantalum ore was carried out according to scheme No. 1. The results are presented in the table.

Based on the results of the work, the following conclusions can be drawn:

The content of useful components in the separation tails is: WO3 according to the first separation scheme - 0.031±0.011%, according to the second - 0.048±0.013%; Ta 2 O 5 and Nb 2 O 5 -0.005±0.003%. This suggests that the induction in the working zone of the separator is sufficient to extract weakly magnetic minerals into the magnetic fraction, and the magnetic separator of the SMVI type is suitable for obtaining tailings.

Tests of the SMVI magnetic separator were also carried out on baddeleyite ore in order to extract weakly magnetic iron minerals (hematite) into tailings and purify zirconium concentrate.

The separation resulted in a reduction in the iron content in the non-magnetic product from 5.39% to 0.63% with a recovery of 93%. The content of zirconium in the concentrate increased by 12%.

The separator operation scheme is shown in Fig. one

The use of the SMVI magnetic separator has found wide application in the enrichment of various ores. SMVI can serve both as the main enrichment equipment and as a refinement of concentrates. This is confirmed by successful semi-industrial tests of this equipment.

The chemical element is tungsten.

Before describing the production of tungsten, it is necessary to make a short digression into history. The name of this metal is translated from German as “wolf cream”, the origin of the term goes back to the late Middle Ages.

When obtaining tin from various ores, it was noticed that in some cases it was lost, passing into a foamy slag, "like a wolf devouring its prey."

The metaphor took root, giving the name to the later received metal, it is currently used in many languages ​​​​of the world. But in English, French and some other languages, tungsten is called differently, from the metaphor "heavy stone" (tungsten in Swedish). The Swedish origin of the word is associated with the experiments of the famous Swedish chemist Scheele, who first obtained tungsten oxide from an ore later named after him (scheelite).

Swedish chemist Scheele, who discovered tungsten.

The industrial production of tungsten metal can be divided into 3 stages:

• ore beneficiation and production of tungsten anhydrite;
• reduction to powder metal;
• obtaining a monolithic metal.

Ore enrichment

Tungsten is not found in the free state in nature, it is present only in the composition of various compounds.

• wolframites
• scheelites

These ores often contain small amounts of other substances (gold, silver, tin, mercury, etc.), despite the very low content of additional minerals, sometimes their extraction during enrichment is economically feasible.

1. Enrichment begins with crushing and grinding of rock. Then the material goes to further processing, the methods of which depend on the type of ore. Enrichment of wolframite ores is usually carried out by the gravitational method, the essence of which is the use of the combined forces of earth's gravity and centrifugal force, the minerals are separated by chemical and physical properties - density, particle size, wettability. This is how waste rock is separated, and the concentrate is brought to the required purity using magnetic separation. The content of wolframite in the resulting concentrate ranges from 52 to 85%.
2. Scheelite, unlike wolframite, is not a magnetic mineral, so magnetic separation is not applied to it. For scheelite ores, the enrichment algorithm is different. The main method is flotation (the process of separating particles in an aqueous suspension) followed by the use of electrostatic separation. The concentration of scheelite can be up to 90% at the outlet. Ores are also complex, containing wolframites and scheelites at the same time. For their enrichment, methods are used that combine gravity and flotation schemes.
   
   If further purification of the concentrate to established standards is required, different procedures are used depending on the type of impurities. To reduce the impurity of phosphorus, scheelite concentrates are treated in the cold with hydrochloric acid, while calcite and dolomite are removed. To remove copper, arsenic, bismuth, roasting is used, followed by treatment with acids. There are other cleaning methods as well.

In order to convert tungsten from a concentrate to a soluble compound, several different methods are used.

1. For example, a concentrate is sintered with an excess of soda, thus obtaining sodium wolframite.
2. Another method can also be used - leaching: tungsten is extracted with a soda solution under pressure at high temperature, followed by neutralization and precipitation.
3. Another way is to treat the concentrate with gaseous chlorine. In this process, tungsten chloride is formed, which is then separated from the chlorides of other metals by sublimation. The resulting product can be converted into tungsten oxide or directly processed into elemental metal.

The main result of various enrichment methods is the production of tungsten trioxide. Further, it is he who goes to the production of metallic tungsten. Tungsten carbide is also obtained from it, which is the main component of many hard alloys. There is another product of direct processing of tungsten ore concentrates - ferrotungsten. It is usually smelted for the needs of ferrous metallurgy.

Recovery of tungsten

The resulting tungsten trioxide (tungsten anhydrite) at the next stage must be reduced to the state of the metal. Restoration is most often carried out by the widely used hydrogen method. A moving container (boat) with tungsten trioxide is fed into the furnace, the temperature rises along the way, hydrogen is supplied towards it. As the metal is reduced, the bulk density of the material increases, the volume of container loading decreases by more than half, therefore, in practice, a run in 2 stages is used, through different types of furnaces.

1. At the first stage, dioxide is formed from tungsten trioxide, at the second stage, pure tungsten powder is obtained from dioxide.
2. Then the powder is sieved through a mesh, large particles are additionally ground to obtain a powder with a given grain size.

Sometimes carbon is used to reduce tungsten. This method somewhat simplifies production, but requires higher temperatures. In addition, coal and its impurities react with tungsten, forming various compounds that lead to metal contamination. There are a number of other methods used in production around the world, but in terms of parameters, hydrogen reduction has the highest applicability.

Obtaining monolithic metal

If the first two stages of industrial production of tungsten are well known to metallurgists and have been used for a very long time, then the development of a special technology was required to obtain a monolith from powder. Most metals are obtained by simple melting and then cast into molds, with tungsten due to its main property - infusibility - such a procedure is impossible. The method for obtaining compact tungsten from powder, proposed at the beginning of the 20th century by the American Coolidge, is still used with various variations in our time. The essence of the method is that the powder turns into a monolithic metal under the influence of an electric current. Instead of the usual melting, to obtain metallic tungsten, several stages have to be passed. At the first of them, the powder is pressed into special bars-rods. Then these rods are subjected to a sintering procedure, and this is done in two stages:

1. 1. First, at temperatures up to 1300ºС, the rod is pre-sintered to increase its strength. The procedure is carried out in a special sealed furnace with a continuous supply of hydrogen. Hydrogen is used for additional reduction, it penetrates into the porous structure of the material, and with additional exposure to high temperature, a purely metallic contact is created between the crystals of the sintered bar. The shtabik after this stage is significantly hardened, losing up to 5% in size.
   2. Then proceed to the main stage - welding. This process is carried out at temperatures up to 3 thousandºC. The post is fixed with clamping contacts, and an electric current is passed through it. Hydrogen is also used at this stage - it is needed to prevent oxidation. The current used is very high, for rods with a cross section of 10x10 mm, a current of about 2500 A is required, and for a cross section of 25x25 mm - about 9000 A. The voltage used is relatively small, from 10 to 20 V. For each batch of monolithic metal, a test rod is first welded, it is used to calibrate the welding mode. The duration of welding depends on the size of the rod and usually ranges from 15 minutes to an hour. This stage, like the first one, also leads to a reduction in the size of the rod.

The density and grain size of the resulting metal depend on the initial grain size of the rod and on the maximum welding temperature. The loss of dimensions after two sintering steps is up to 18% in length. The final density is 17–18.5 g/cm².

To obtain high-purity tungsten, various additives are used that evaporate during welding, for example, oxides of silicon and alkali metals. As they heat up, these additives evaporate, taking other impurities with them. This process contributes to additional purification. When using the correct temperature regime and the absence of traces of moisture in the hydrogen atmosphere during sintering, with the help of such additives, the degree of purification of tungsten can be increased to 99.995%.

Manufacture of products from tungsten

Obtained from the original ore after the described three stages of production, monolithic tungsten has a unique set of properties. In addition to refractoriness, it has a very high dimensional stability, strength retention at high temperatures and the absence of internal stress. Tungsten also has good ductility and ductility. Further production most often consists in drawing the wire. These are technologically relatively simple processes.

1. The blanks enter the rotary forging machine, where the material is reduced.
2. Then, by drawing, a wire of various diameters is obtained (drawing is pulling a rod on special equipment through tapering holes). So you can get the thinnest tungsten wire with a total degree of deformation of 99.9995%, while its strength can reach 600 kg / mm².

Tungsten began to be used for the filaments of electric lamps even before the development of a method for the production of malleable tungsten. The Russian scientist Lodygin, who had previously patented the principle of using a filament for a lamp, in the 1890s proposed using a tungsten wire twisted into a spiral as such a filament. How was tungsten obtained for such wires? First, a mixture of tungsten powder with some plasticizer (for example, paraffin) was prepared, then a thin thread was pressed out of this mixture through a hole of a given diameter, dried, and calcined in hydrogen. A rather fragile wire was obtained, the rectilinear segments of which were attached to the lamp electrodes. There were attempts to obtain a compact metal by other methods, however, in all cases, the fragility of the threads remained critically high. After the work of Coolidge and Fink, the manufacture of tungsten wire gained a solid technological base, and the industrial use of tungsten began to grow rapidly.

An incandescent lamp invented by the Russian scientist Lodygin.

World tungsten market

Tungsten production volumes are about 50 thousand tons per year. The leader in production, as well as in consumption, is China, this country produces about 41 thousand tons per year (Russia, for comparison, produces 3.5 thousand tons). An important factor at present is the processing of secondary raw materials, usually scrap tungsten carbide, shavings, sawdust and powdered tungsten residues, such processing provides about 30% of the world's consumption of tungsten.

Filaments from burned-out incandescent lamps are practically not recycled.

The global tungsten market has recently shown a decline in demand for tungsten filaments. This is due to the development of alternative technologies in the field of lighting - fluorescent and LED lamps are aggressively replacing conventional incandescent lamps both in everyday life and in industry. Experts predict that the use of tungsten in this sector will decrease by 5% per year in the coming years. Demand for tungsten as a whole is not decreasing, the drop in applicability in one sector is offset by growth in others, including innovative industries.

Tungsten minerals, ores and concentrates

Tungsten is a rare element, its average content in the earth's crust is Yu-4% (by mass). About 15 minerals of tungsten are known, however, only minerals of the wolframite group and scheelite are of practical importance.

Wolframite (Fe, Mn)WO4 is an isomorphic mixture (solid solution) of iron and manganese tungstates. If there is more than 80% iron tungstate in the mineral, the mineral is called ferberite, in the case of the predominance of manganese tungstate (more than 80%) - hübnerite. Mixtures lying in composition between these limits are called wolframites. Minerals of the wolframite group are colored black or brown and have a high density (7D-7.9 g/cm3) and a hardness of 5-5.5 on the mineralogical scale. The mineral contains 76.3-76.8% W03. Wolframite is weakly magnetic.

Scheelite CaWOA is calcium tungstate. The color of the mineral is white, gray, yellow, brown. Density 5.9-6.1 g/cm3, hardness according to the mineralogical scale 4.5-5. Scheelite often contains an isomorphic admixture of powellite, CaMo04. When irradiated with ultraviolet rays, scheelite fluoresces blue - blue light. At a molybdenum content of more than 1%, fluorescence becomes yellow. Scheelite is non-magnetic.

Tungsten ores are usually poor in tungsten. The minimum content of W03 in ores, at which their exploitation is profitable, is currently 0.14-0.15% for large and 0.4-0.5% for small deposits.

Together with tungsten minerals, molybdenite, cassiterite, pyrite, arsenopyrite, chalcopyrite, tantalite or columbite, etc. are found in ores.

According to the mineralogical composition, two types of deposits are distinguished - wolframite and scheelite, and according to the shape of ore formations - vein and contact types.

In vein deposits, tungsten minerals mostly occur in quartz veins of small thickness (0.3-1 m). The contact type of deposits is associated with zones of contact between granite rocks and limestones. They are characterized by deposits of scheelite-bearing skarn (skarns are silicified limestones). The skarn-type ores include the Tyrny-Auzskoye deposit, the largest in the USSR, in the North Caucasus. During the weathering of vein deposits, wolframite and scheelite accumulate, forming placers. In the latter, wolframite is often combined with cassiterite.

Tungsten ores are enriched to obtain standard concentrates containing 55-65% W03. A high degree of enrichment of wolframite ores is achieved using various methods: gravity, flotation, magnetic and electrostatic separation.

When enriching scheelite ores, gravity-flotation or purely flotation schemes are used.

The extraction of tungsten into conditioned concentrates during the enrichment of tungsten ores ranges from 65-70% to 85-90%.

When enriching ores of complex composition or difficult to enrich, it is sometimes economically advantageous to remove middlings with a content of 10–20% W03 from the enrichment cycle for chemical (hydrometallurgical) processing, as a result of which "artificial scheelite" or technical tungsten trioxide is obtained. Such combined schemes provide a high extraction of tungsten from ores.

The state standard (GOST 213-73) provides for the content of W03 in tungsten concentrates of the 1st grade not less than 65%, the 2nd grade - not less than 60%. They limit the content of impurities P, S, As, Sn, Cu, Pb, Sb, Bi in the range from hundredths of a percent to 1.0%, depending on the grade and purpose of the concentrate.

The explored reserves of tungsten as of 1981 are estimated at 2903 thousand tons, of which 1360 thousand tons are in the PRC. The USSR, Canada, Australia, the USA, South and North Korea, Bolivia, Brazil, and Portugal have significant reserves. Production of tungsten concentrates in capitalist and developing countries in the period 1971 - 1985 fluctuated within 20 - 25 thousand tons (in terms of metal content).

Methods for processing tungsten concentrates

The main product of the direct processing of tungsten concentrates (apart from ferrotungsten, smelted for the needs of ferrous metallurgy) is tungsten trioxide. It serves as the starting material for tungsten and tungsten carbide, the main constituent of hard alloys.

Production schemes for the processing of tungsten concentrates are divided into two groups depending on the accepted method of decomposition:

Tungsten concentrates are sintered with soda or treated with aqueous soda solutions in autoclaves. Tungsten concentrates are sometimes decomposed with aqueous solutions of sodium hydroxide.

Concentrates are decomposed by acids.

In cases where alkaline reagents are used for decomposition, solutions of sodium tungstate are obtained, from which, after purification from impurities, end products are produced - ammonium paratungstate (PVA) or tungstic acid. 24

When the concentrate is decomposed by acids, precipitation of technical tungstic acid is obtained, which is purified from impurities in subsequent operations.

Decomposition of tungsten concentrates. alkaline reagents Sintering with Na2C03

Sintering wolframite with Na2C03. The interaction of wolframite with soda in the presence of oxygen proceeds actively at 800-900 C and is described by the following reactions: 2FeW04 + 2Na2C03 + l/202 = 2Na2W04 + Fe203 + 2C02; (l) 3MnW04 + 3Na2C03 + l/202 = 3Na2W04 + Mn304 + 3C02. (2)

These reactions proceed with a large loss of Gibbs energy and are practically irreversible. With the ratio in wolframite FeO:MnO = i:i AG ° 1001C = -260 kJ / mol. With an excess of Na2C03 in the charge of 10-15% in excess of the stoichiometric amount, complete decomposition of the concentrate is achieved. To accelerate the oxidation of iron and manganese, sometimes 1-4% nitrate is added to the charge.

Sintering wolframite with Na2C03 at domestic enterprises is carried out in tubular rotary kilns lined with fireclay bricks. In order to avoid the melting of the charge and the formation of deposits (growths) in the zones of the furnace with a lower temperature, tailings from the leaching of cakes (containing iron and manganese oxides) are added to the charge, reducing the content of W03 in it to 20-22%.

The furnace, 20 m long and with an outer diameter of 2.2 m, at a rotation speed of 0.4 rpm and an inclination of 3, has a capacity of 25 t/day in terms of charge.

The components of the charge (crushed concentrate, Na2C03, saltpeter) are fed from the hoppers to the screw mixer using automatic scales. The mixture enters the furnace hopper, from which it is fed into the furnace. After exiting the kiln, the sinter pieces pass through the crushing rolls and the wet grinding mill, from which the pulp is sent to the upper polisher (Fig. 1).

Scheelite sintering with Na2C03. At temperatures of 800-900 C, the interaction of scheelite with Na2C03 can proceed according to two reactions:

CaW04 + Na2CQ3 Na2W04 + CaCO3; (1.3)

CaW04 + Na2C03 *=*■ Na2W04 + CaO + C02. (1.4)

Both reactions proceed with a relatively small change in the Gibbs energy.

Reaction (1.4) proceeds to an appreciable extent above 850 C, when decomposition of CaCO3 is observed. The presence of calcium oxide in the sinter leads, when the sinter is leached with water, to the formation of poorly soluble calcium tungstate, which reduces the extraction of tungsten into solution:

Na2W04 + Ca(OH)2 = CaW04 + 2NaOH. (1.5)

With a large excess of Na2CO3 in the charge, this reaction is largely suppressed by the interaction of Na2CO4 with Ca(OH)2 to form CaCO3.

To reduce the consumption of Na2C03 and prevent the formation of free calcium oxide, quartz sand is added to the mixture to bind calcium oxide into insoluble silicates:

2CaW04 + 2Na2C03 + Si02 = 2Na2W04 + Ca2Si04 + 2C02;(l.6) AG°100IC = -106.5 kJ.

Nevertheless, in this case, too, to ensure a high degree of tungsten extraction into the solution, a significant excess of Na2CO3 (50–100% of the stoichiometric amount) must be introduced into the charge.

The sintering of the scheelite concentrate charge with Na2C03 and quartz sand is carried out in drum furnaces, as described above for wolframite at 850–900°C. To prevent melting, leaching dumps (containing mainly calcium silicate) are added to the charge at the rate of reducing the content of W03 to 20-22%.

Leaching of soda specks. When cakes are leached with water, sodium tungstate and soluble salts of impurities (Na2Si03, Na2HP04, Na2HAs04, Na2Mo04, Na2S04), as well as an excess of Na2C03, pass into the solution. Leaching is carried out at 80-90 ° C in steel reactors with mechanical agitation, operating in hierio-

Concentrates with soda:

Elevator feeding the concentrate to the mill; 2 - ball mill operating in a closed cycle with an air separator; 3 - auger; 4 - air separator; 5 - bag filter; 6 - automatic weight dispensers; 7 - conveying auger; 8 - screw mixer; 9 - charge hopper; 10 - feeder;

Drum oven; 12 - roll crusher; 13 - rod mill-leacher; 14 - reactor with stirrer

Wild mode, or continuous drum rotary lixiviators. The latter are filled with crushing rods for crushing pieces of cake.

The extraction of tungsten from the sinter into the solution is 98-99%. Strong solutions contain 150-200 g/l W03.

Autoclave o-c One method of decomposition of tungsten concentrates

The autoclave-soda method was proposed and developed in the USSR1 in relation to the processing of scheelite concentrates and middlings. Currently, the method is used in a number of domestic factories and in foreign countries.

The decomposition of scheelite with Na2C03 solutions is based on the exchange reaction

CaW04CrB)+Na2C03(pacTB)^Na2W04(pacTB)+CaC03(TB). (1.7)

At 200-225 °C and the corresponding excess of Na2C03, depending on the composition of the concentrate, decomposition proceeds with sufficient speed and completeness. The concentration equilibrium constants of reaction (1.7) are small, increase with temperature, and depend on the soda equivalent (i.e., the number of moles of Na2C03 per 1 mole of CaW04).

With a soda equivalent of 1 and 2 at 225 C, the equilibrium constant (Kc = C / C cq) is 1.56 and

0.99 respectively. It follows from this that at 225 C the minimum required soda equivalent is 2 (i.e., the excess of Na2C03 is 100%). The actual excess of Na2C03 is higher, since the rate of the process slows down as equilibrium is approached. For scheelite concentrates with a content of 45-55% W03 at 225 C, a soda equivalent of 2.6-3 is required. For middlings containing 15-20% W03, 4-4.5 moles of Na2C03 per 1 mole of CaW04 are required.

CaCO3 films formed on scheelite particles are porous and up to a thickness of 0.1-0.13 mm their influence on the rate of scheelite decomposition by Na2CO3 solutions was not found. With intensive stirring, the rate of the process is determined by the rate of the chemical stage, which is confirmed by the high value of the apparent activation energy E = 75+84 kJ/mol. However, in case of insufficient stirring speed (which

Occurs in horizontal rotating autoclaves), an intermediate regime is realized: the rate of the process is determined both by the rate of supply of the reagent to the surface and the rate of chemical interaction.

0.2 0.3 0, it 0.5 0.5 0.7 0.8

As can be seen from Fig. 2, the specific reaction rate decreases approximately in inverse proportion to the increase in the ratio of molar concentrations of Na2W04:Na2C03 in solution. This is

Ryas. Fig. 2. Dependence of the specific rate of scheelite decomposition by a soda solution in an autoclave j on the molar ratio of Na2W04/Na2C03 concentrations in the solution at

Causes the need for a significant excess of Na2C03 against the minimum required, determined by the value of the equilibrium constant. To reduce the consumption of Na2C03, a two-stage countercurrent leaching is carried out. In this case, the tailings after the first leaching, in which there is little tungsten (15-20% of the original), are treated with a fresh solution containing a large excess of Na2C03. The resulting solution, which is circulating, enters the first stage of leaching.

Decomposition with Na2C03 solutions in autoclaves is also used for wolframite concentrates, however, the reaction in this case is more complicated, since it is accompanied by hydrolytic decomposition of iron carbonate (manganese carbonate is only partially hydrolyzed). The decomposition of wolframite at 200-225 °C can be represented by the following reactions:

MnW04(TB)+Na2C03(paCT)^MiiC03(TB)+Na2W04(paCTB); (1.8)

FeW04(TB)+NaC03(pacT)*=iFeC03(TB)+Na2W04(paCTB); (1.9)

FeC03 + HjO^FeO + H2CO3; (1.10)

Na2C03 + H2C03 = 2NaHC03. (l. ll)

The resulting iron oxide FeO at 200-225 ° C undergoes a transformation according to the reaction:

3FeO + H20 = Fe304 + H2.

The formation of sodium bicarbonate leads to a decrease in the concentration of Na2CO3 in the solution and requires a large excess of the reagent.

To achieve satisfactory decomposition of wolframite concentrates, it is necessary to grind them finely and increase the consumption of Na2C03 to 3.5-4.5 g-eq, depending on the composition of the concentrate. High-manganese wolframites are more difficult to decompose.

The addition of NaOH or CaO to the autoclaved slurry (which leads to causticization of Na2C03) improves the degree of decomposition.

The decomposition rate of wolframite can be increased by introducing oxygen (air) into the autoclave pulp, which oxidizes Fe (II) and Mil (II), which leads to the destruction of the crystal lattice of the mineral on the reacting surface.

secondary steam

Ryas. 3. Autoclave unit with a horizontally rotating autoclave: 1 - autoclave; 2 - loading pipe for the pulp (steam is introduced through it); 3 - pulp pump; 4 - pressure gauge; 5 - pulp reactor-heater; 6 - self-evaporator; 7 - drop separator; 8 - pulp input into the self-evaporator; 9 - chipper made of armored steel; 10 - pipe for pulp removal; 11 - pulp collector

Leaching is carried out in steel horizontal rotating autoclaves heated with live steam (Fig. 3) and vertical continuous autoclaves with stirring of the pulp with bubbling steam. Approximate process mode: temperature 225 pressure in the autoclave ~ 2.5 MPa, ratio T: W = 1: (3.5 * 4), duration at each stage 2-4 hours.

Figure 4 shows a diagram of an autoclave battery. The initial autoclave pulp, heated by steam to 80-100 °C, is pumped into autoclaves, where it is heated to

secondary steam

Ditch. Fig. 4. Scheme of a continuous autoclave plant: 1 - reactor for heating the initial pulp; 2 - piston pump; 3 - autoclave; 4 - throttle; 5 - self-evaporator; 6 - pulp collector

200-225 °C live steam. In continuous operation, the pressure in the autoclave is maintained by discharging the slurry through a throttle (calibrated carbide washer). The pulp enters the self-evaporator - a vessel under pressure of 0.15-0.2 MPa, where the pulp is rapidly cooled due to intensive evaporation. The advantages of autoclave-soda decomposition of scheelite concentrates before sintering are the exclusion of the furnace process and a somewhat lower content of impurities in tungsten solutions (especially phosphorus and arsenic).

The disadvantages of the method include a large consumption of Na2C03. A high concentration of excess Na2C03 (80-120 g/l) entails an increased consumption of acids for the neutralization of solutions and, accordingly, high costs for the disposal of waste solutions.

Decomposition of tungstate conc.

Sodium hydroxide solutions decompose wolframite according to the exchange reaction:

Me WC>4 + 2Na0Hi=tNa2W04 + Me(0 H)2, (1.13)

Where Me is iron, manganese.

The value of the concentration constant of this reaction Kc = 2 at temperatures of 90, 120 and 150 °C is equal to 0.68, respectively; 2.23 and 2.27.

Complete decomposition (98-99%) is achieved by treating the finely divided concentrate with 25-40% sodium hydroxide solution at 110-120°C. The required excess of alkali is 50% or more. The decomposition is carried out in steel sealed reactors equipped with stirrers. The passage of air into the solution accelerates the process due to the oxidation of iron (II) hydroxide Fe (OH) 2 into hydrated iron (III) oxide Fe203-«H20 and manganese (II) hydroxide Mn (OH) 2 into hydrated manganese (IV) oxide Mn02-lH20 .

The use of decomposition with alkali solutions is advisable only for high-grade wolframite concentrates (65-70% W02) with a small amount of silica and silicate impurities. When processing low-grade concentrates, highly contaminated solutions and hard-to-filter precipitates are obtained.

Processing of sodium tungstate solutions

Solutions of sodium tungstate containing 80-150 g/l W03, in order to obtain tungsten trioxide of the required purity, have so far been mainly processed according to the traditional scheme, which includes: purification from compounds of impurity elements (Si, P, As, F, Mo); precipitation

Calcium tungsten mag (artificial scheelite) with its subsequent decomposition with acids and obtaining technical tungstic acid; dissolution of tungstic acid in ammonia water, followed by evaporation of the solution and crystallization of ammonium paratungstate (PVA); calcination of PVA to obtain pure tungsten trioxide.

The main drawback of the scheme is its multi-stage nature, carrying out most of the operations in a periodic mode, and the duration of a number of redistributions. An extraction and ion-exchange technology for converting Na2W04 solutions into (NH4)2W04 solutions has been developed and is already being used at some enterprises. The main redistributions of the traditional scheme and new extraction and ion-exchange variants of the technology are briefly considered below.

Purification of impurities

Silicon cleaning. When the content of Si02 in solutions exceeds 0.1% of the content of W03, preliminary purification from silicon is necessary. Purification is based on the hydrolytic decomposition of Na2Si03 by boiling a solution neutralized to pH=8*9 with the release of silicic acid.

The solutions are neutralized with hydrochloric acid, added in a thin stream with stirring (to avoid local peroxidation) to a heated solution of sodium tungstate.

Purification of phosphorus and arsenic. To remove phosphate and arsenate ions, the method of precipitation of ammonium-magnesium salts Mg (NH4) P04 6H20 and Mg (NH4) AsC) 4 6H20 is used. The solubility of these salts in water at 20 C is 0.058 and 0.038%, respectively. In the presence of an excess of Mg2+ and NH4 ions, the solubility is lower.

The precipitation of phosphorus and arsenic impurities is carried out in the cold:

Na2HP04 + MgCl2 + NH4OH = Mg(NH4)P04 + 2NaCl +

Na2HAsQ4 + MgCl2 + NH4OH = Mg(NH4)AsQ4 + 2NaCl +

After a long standing (48 hours), crystalline precipitates of ammonium-magnesium salts precipitate from the solution.

Purification from fluoride ions. With a high content of fluorite in the original concentrate, the content of fluoride ions reaches 5 g/l. Solutions are purified from fluoride - ions by precipitation with magnesium fluoride from a neutralized solution, to which MgCl2 is added. Purification of fluorine can be combined with hydrolytic isolation of silicic acid.

Molybdenum cleaning. Solutions of sodium tungstate" must be purified from molybdenum if its content exceeds 0.1% of the W03 content (i.e. 0.1-0.2 t / l). At a molybdenum concentration of 5-10 g / l ( for example, in the processing of scheelite-powellite Tyrny-Auzsky concentrates), the isolation of molybdenum is of particular importance, since it is aimed at obtaining a molybdenum chemical concentrate.

A common method is to precipitate the sparingly soluble molybdenum trisulfide MoS3 from a solution.

It is known that when sodium sulfide is added to solutions of tungstate or sodium molybdate, sulfosalts Na23S4 or oxosulfosalts Na23Sx04_x (where E is Mo or W) are formed:

Na2304 + 4NaHS = Na23S4 + 4NaOH. (1.16)

The equilibrium constant of this reaction for Na2Mo04 is much larger than for Na2W04(^^0 » Kzr). Therefore, if an amount of Na2S is added to the solution, sufficient only for interaction with Na2Mo04 (with a slight excess), then molybdenum sulfosalt is predominantly formed. With the subsequent acidification of the solution to pH = 2.5 * 3.0, the sulfosalt is destroyed with the release of molybdenum trisulfide:

Na2MoS4 + 2HC1 = MoS3 j + 2NaCl + H2S. (1.17)

Oxosulfosalts decompose with the release of oxosulfides (for example, MoSjO, etc.). Together with molybdenum trisulfide, a certain amount of tungsten trisulfide co-precipitates. By dissolving the sulfide precipitate in a soda solution and re-precipitating molybdenum trisulfide, a molybdenum concentrate is obtained with a W03 content of not more than 2% with a loss of tungsten 0.3-0.5% of the initial amount.

After partial oxidative roasting of the precipitate of molybdenum trisulfide (at 450-500 ° C), a molybdenum chemical concentrate is obtained with a content of 50-52% molybdenum.

The disadvantage of the method of precipitation of molybdenum in the composition of trisulfide is the release of hydrogen sulfide according to reaction (1.17), which requires expenses for the neutralization of gases (they use the absorption of H2S in a scrubber irrigated with a sodium hydroxide solution). The selection of molybdenum trisulfide is carried out from a solution heated to 75-80 C. The operation is carried out in sealed steel reactors, gummed or coated with acid-resistant enamel. The trisulfide precipitates are separated from the solution by filtration on a filter press.

Obtaining tungstic acid from solutions of sodium tungstate

Tungstic acid can be directly isolated from a solution of sodium tungstate with hydrochloric or nitric acid. However, this method is rarely used due to the difficulty of washing precipitates from sodium ions, the content of which in tungsten trioxide is limited.

For the most part, calcium tungstate is initially precipitated from the solution, which is then decomposed with acids. Calcium tungstate is precipitated by adding a CaCl2 solution heated to 80-90 C to a sodium tungstate solution with a residual alkalinity of the solution of 0.3-0.7%. In this case, a white finely crystalline, easily settled precipitate falls out, sodium ions remain in the mother liquor, which ensures their low content in tungstic acid. 99-99.5% W precipitates from the solution, mother solutions contain 0.05-0.07 g/l W03. The CaW04 precipitate washed with water in the form of a paste or pulp enters for decomposition with hydrochloric acid when heated to 90 °:

CaW04 + 2HC1 = H2W04i + CaCl2. (1.18)

During decomposition, a high final acidity of the pulp is maintained (90–100 g/l HCI), which ensures the separation of tungstic acid from impurities of phosphorus, arsenic, and partly molybdenum compounds (molybdic acid dissolves in hydrochloric acid). Precipitates of tungstic acid require thorough washing from impurities (especially from calcium salts

and sodium). In recent years, continuous washing of tungstic acid in pulsating columns has been mastered, which greatly simplified the operation.

At one of the enterprises in the USSR, when processing sodium tungstate solutions, instead of hydrochloric acid, nitric acid is used to neutralize the solutions and decompose CaW04 precipitates, and the precipitation of the latter is carried out by introducing Ca(N03)2 into the solutions. In this case, the nitric acid mother liquors are disposed of, obtaining nitrate salts used as fertilizer.

Purification of technical tungstic acid and obtaining W03

Technical tungstic acid, obtained by the method described above, contains 0.2-0.3% impurities. As a result of acid calcination at 500-600 C, tungsten trioxide is obtained, suitable for the production of hard alloys based on tungsten carbide. However, the production of tungsten requires trioxide of a higher purity with a total impurity content of no more than 0.05%.

The ammonia method for purifying tungstic acid is generally accepted. It is easily soluble in ammonia water, while most of the impurities remain in the sediment: silica, iron and manganese hydroxides, and calcium (in the form of CaW04). However, ammonia solutions may contain an admixture of molybdenum, alkali metal salts.

From the ammonia solution, as a result of evaporation and subsequent cooling, a crystalline precipitate of PVA is isolated:

Evaporation

12(NH4)2W04 * (NH4)10H2W12O42 4Н20 + 14NH3 +

In industrial practice, the composition of PVA is often written in the oxide form: 5(NH4)20-12W03-5H20, which does not reflect its chemical nature as an isopoly acid salt.

Evaporation is carried out in batch or continuous devices made of stainless steel. Usually 75-80% of tungsten is isolated into crystals. Deeper crystallization is undesirable in order to avoid contamination of the crystals with impurities. It is significant that most of the molybdenum impurity (70-80%) remains in the mother liquor. From the mother liquor enriched with impurities, tungsten is precipitated in the form of CaW04 or H2W04, which is returned to the appropriate stages of the production scheme.

PVA crystals are squeezed out on a filter, then in a centrifuge, washed with cold water and dried.

Tungsten trioxide is obtained by thermal decomposition of tungstic acid or PVA:

H2W04 \u003d "W03 + H20;

(NH4) 10H2W12O42 4H20 = 12W03 + 10NH3 + 10H20. (1.20)

Calcination is carried out in rotary electric furnaces with a pipe made of heat-resistant steel 20X23H18. The calcination mode depends on the purpose of tungsten trioxide, the required size of its particles. So, to obtain tungsten wire grade VA (see below), PVA is calcined at 500-550 ° C, wire grades VCh and VT (tungsten without additives) - at 800-850 ° C.

Tungstic acid is calcined at 750-850 °C. Tungsten trioxide derived from PVA has larger particles than trioxide derived from tungstic acid. In tungsten trioxide, intended for the production of tungsten, the content of W03 must be at least 99.95% for the production of hard alloys - at least 99.9%.

Extraction and ion-exchange methods for processing solutions of sodium tungstate

The processing of sodium tungstate solutions is greatly simplified when tungsten is extracted from solutions by extraction with an organic extractant, followed by re-extraction from the organic phase with an ammonia solution with separation of PVA from an ammonia solution.

Since in a wide range of pH=7.5+2.0 tungsten is found in solutions in the form of polymeric anions, anion-exchange extractants are used for extraction: salts of amines or quaternary ammonium bases. In particular, the sulfate salt of trioctylamine (i?3NH)HS04 (where R is С8Н17) is used in industrial practice. The highest rates of tungsten extraction are observed at pH=2*4.

Extraction is described by the equation:

4 (i? 3NH) HS04 (opr) + H2 \ U120 * "(aq) + 2H + (aq) ї \u003d ї

Ї \u003d ї (D3GSh) 4H4 \ U12O40 (org) + 4H80; (aq.). (l.2l)

The amine is dissolved in kerosene, to which a technical mixture of polyhydric alcohols (C7 - C9) is added to prevent the precipitation of a solid phase (due to the low solubility of amine salts in kerosene). The approximate composition of the organic phase: amines 10%, alcohols 15%, kerosene - the rest.

Solutions purified from mrlibden, as well as impurities of phosphorus, arsenic, silicon and fluorine, are sent for extraction.

Tungsten is re-extracted from the organic phase with ammonia water (3-4% NH3), obtaining solutions of ammonium tungstate, from which PVA is isolated by evaporation and crystallization. The extraction is carried out in mixer-settler type apparatuses or in pulsating columns with packing.

The advantages of extraction processing of sodium tungstate solutions are obvious: the number of operations of the technological scheme is reduced, it is possible to carry out a continuous process for obtaining ammonium tungstate solutions from sodium tungstate solutions, and production areas are reduced.

Wastewater from the extraction process may contain an admixture of 80-100 mg/l of amines, as well as impurities of higher alcohols and kerosene. To remove these environmentally harmful impurities, froth flotation and adsorption on activated carbon are used.

Extraction technology is used at foreign enterprises and is also implemented at domestic plants.

The use of ion-exchange resins is a direction of the scheme for processing sodium tungstate solutions that competes with extraction. For this purpose, low-basic anion exchangers containing amine groups (often tertiary amines) or amphoteric resins (ampholytes) containing carboxyl and amine groups are used. At pH=2.5+3.5, tungsten polyanions are sorbed on resins, and for some resins the total capacity is 1700-1900 mg W03 per 1 g of resin. In the case of resin in the 8C>5~ form, sorption and elution are described by the equations, respectively:

2tf2S04 + H4W12044; 5^"4H4W12O40 + 2SOf; (1.22)

I?4H4WI2O40 + 24NH4OH = 12(NH4)2W04 + 4DON + 12H20. (l.23)

The ion-exchange method was developed and applied at one of the enterprises of the USSR. The required contact time of the resin with the solution is 8-12 hours. The process is carried out in a cascade of ion-exchange columns with a suspended resin bed in a continuous mode. A complicating circumstance is the partial isolation of PVA crystals at the stage of elution, which requires their separation from the resin particles. As a result of elution, solutions containing 150–170 g/l W03 are obtained, which are fed to the evaporation and crystallization of PVA.

The disadvantage of ion-exchange technology compared to extraction is the unfavorable kinetics (contact time 8-12 hours versus 5-10 minutes for extraction). At the same time, the advantages of ion exchangers include the absence of waste solutions containing organic impurities, as well as the fire safety and non-toxicity of resins.

Decomposition of scheelite concentrates with acids

In industrial practice, mainly in the processing of high-grade scheelite concentrates (70-75% W03), direct decomposition of scheelite with hydrochloric acid is used.

Decomposition reaction:

CaW04 + 2HC1 = W03H20 + CoCl2 (1.24)

Almost irreversible. However, the acid consumption is much higher than the stoichiometrically required one (250–300%) due to the inhibition of the process by tungstic acid films on scheelite particles.

The decomposition is carried out in sealed reactors with stirrers, lined with acid-resistant enamel and heated through a steam jacket. The process is carried out at 100-110 C. The duration of decomposition varies from 4-6 to 12 hours, which depends on the degree of grinding, as well as the origin of the concentrate (scheelites of various deposits differ in reactivity).

A single treatment does not always lead to a complete opening. In this case, after dissolving tungstic acid in ammonia water, the residue is re-treated with hydrochloric acid.

During the decomposition of scheelite-powellite concentrates with a content of 4-5% molybdenum, most of the molybdenum passes into the hydrochloric acid solution, which is explained by the high solubility of molybdic acid in hydrochloric acid. So, at 20 C in 270 g/l HC1, the solubilities of H2Mo04 and H2WO4 are 182 and 0.03 g/l, respectively. Despite this, complete separation of molybdenum is not achieved. Precipitates of tungstic acid contain 0.2-0.3% molybdenum, which cannot be extracted by re-treatment with hydrochloric acid.

The acid method differs from the alkaline methods of scheelite decomposition by a smaller number of operations of the technological scheme. However, when processing concentrates with a relatively low content of W03 (50-55%) with a significant content of impurities, in order to obtain conditioned ammonium paratungstate, two or three ammonia purifications of tungstic acid have to be carried out, which is uneconomical. Therefore, decomposition with hydrochloric acid is mostly used in the processing of rich and pure scheelite concentrates.

The disadvantages of the method of decomposition with hydrochloric acid are the high consumption of acid, the large volume of waste solutions of calcium chloride and the complexity of their disposal.

In the light of the tasks of creating waste-free technologies, the nitric acid method of decomposition of scheelite concentrates is of interest. In this case, the mother solutions are easy to dispose of, obtaining nitrate salts.

Page 1 of 25

State budget professional

educational institution of the Republic of Karelia

"Kostomuksha Polytechnic College"

Deputy director for ML __________________ T.S. Kubar

"_____" _________________________________ 2019

FINAL QUALIFICATION WORK

Subject: "Maintaining the main method of enrichment of tungsten ores and the use of auxiliary dehydration processes in the technological scheme of Primorsky GOK"

Student of the group: Kuzich S.E.

4 course, group OPI-15 (41С)

Specialty 21.02.18

"Mineral Enrichment"

Head of the WRC: Volkovich O.V.

special teacher disciplines

Kostomuksha

2019

Introduction…………………………………………………………………………...…3

1. Technological part……………………………………………………………6

1.1 General characteristics of tungsten ores………………………………….6

1.2 Economic evaluation of tungsten ores…………………………...……10

1. Technological scheme of enrichment of tungsten ores on the example of Primorsky GOK………………………………………………………..……11

2. Dehydration of enrichment products…………………………………......17

2.1. The essence of dehydration processes……………………………………..….17

2.2. Centrifugation…………………………………………………..…….24

3. Organization of safe working conditions……………………………………….30

3.1. Requirements for the creation of safe working conditions in the workplace…………………………………………………………………..…...30

3.2. Requirements for maintaining safety in the workplace.…….…..32

3.3. Safety requirements for employees of the enterprise…………32

Conclusion……………………………………………………………….…..…..34

List of used sources and literature……………………....…...36

Introduction

Mineral enrichment - is an industry that processes solid minerals with the intent to obtain concentrates, i.e. products, the quality of which is higher than the quality of the raw materials and meets the requirements for their further use in the national economy.Minerals are the basis of the national economy, and there is not a single industry where minerals or products of their processing are not used.

One of these minerals is tungsten - a metal with unique properties. It has the highest boiling and melting point among metals, while having the lowest coefficient of thermal expansion. In addition, it is one of the hardest, heaviest, stable and dense metals: the density of tungsten is comparable to the density of gold and uranium and is 1.7 times higher than that of lead.The main tungsten minerals are scheelite, hübnerite and wolframite. Depending on the type of minerals, ores can be divided into two types; scheelite and wolframite. When processing tungsten-containing ores, gravitational, flotation, magnetic, and also electrostatic,hydrometallurgical and other methods.

In recent years, cermet hard alloys based on tungsten carbide have been widely used. Such alloys are used as cutters, for the manufacture of drill bits, dies for cold wire drawing, dies, springs, parts of pneumatic tools, valves of internal combustion engines, heat-resistant parts of mechanisms operating at high temperatures. Surfacing hard alloys (stellites), consisting of tungsten (3-15%), chromium (25-35%) and cobalt (45-65%) with a small amount of carbon, are used for coating fast-wearing parts of mechanisms (turbine blades, excavator equipment and etc.). Alloys of tungsten with nickel and copper are used in the manufacture of protective screens from gamma rays in medicine.

Metal tungsten is used in electrical engineering, radio engineering, X-ray engineering: for the manufacture of filaments in electric lamps, heaters for high-temperature electric furnaces, anticathodes and cathodes of X-ray tubes, vacuum equipment and much more. Tungsten compounds are used as dyes, to impart fire resistance and water resistance to fabrics, in chemistry - as a sensitive reagent for alkaloids, nicotine, protein, as a catalyst in the production of high-octane gasoline.

Tungsten is also widely used in the production of military and space technology (armor plates, tank turrets, rifle and gun barrels, rocket cores, etc.).

The structure of tungsten consumption in the world is constantly changing. From some industries, it is being replaced by other materials, but new areas of its application are emerging. So, in the first half of the 20th century, up to 90% of tungsten was spent on alloying steels. At present, the industry is dominated by the production of tungsten carbide, and the use of tungsten metal is becoming increasingly important. Recently, new possibilities of using tungsten as an environmentally friendly material have been opened up. Tungsten can replace lead in the production of various ammunition, and also find application in the manufacture of sports equipment, in particular golf clubs and balls. Developments in these areas are underway in the United States. In the future, tungsten should replace depleted uranium in the production of large-caliber ammunition. In the 1970s, when tungsten prices were about $170. per 1% WO content 3 per 1 ton of product, the United States, and then some NATO countries, replaced tungsten in heavy ammunition with depleted uranium, which, with the same technical characteristics, was significantly cheaper.

Tungsten, as a chemical element, is included in the group of heavy metals and, from an environmental point of view, belongs to moderately toxic (II-III class). At present, the sources of environmental pollution with tungsten are the processes of exploration, extraction and processing (enrichment and metallurgy) of tungsten-containing mineral raw materials. As a result of processing, such sources are unused solid waste, sewage, dust tungsten-containing fine particles. Solid wastes in the form of dumps and various tailings are formed during the enrichment of tungsten ores. Wastewater from the processing plants is represented by tailing dumps, which are used as recycled water in the grinding and flotation processes.

The purpose of the final qualifying work: to substantiate the technological scheme of enrichment of tungsten ores on the example of Primorsky GOK and the essence of the dehydration processes in this technological scheme.

The invention relates to a method for the complex processing of tailings for the enrichment of tungsten-containing ores. The method includes their classification into fine and coarse fractions, screw separation of the fine fraction to obtain a tungsten product and its repurification. At the same time, recleaning is carried out on a screw separator to obtain a crude tungsten concentrate, which is subjected to finishing on concentration tables to obtain a gravitational tungsten concentrate, which is subjected to flotation to obtain a high-grade conditioned tungsten concentrate and a sulfide-containing product. The tails of the screw separator and the concentration table are combined and subjected to thickening. At the same time, the drain obtained after thickening is fed to the classification of tailings for the enrichment of tungsten-containing ores, and the thickened product is subjected to enrichment on a screw separator to obtain secondary tailings and a tungsten product, which is sent for cleaning. The technical result is to increase the depth of processing of tailings for the enrichment of tungsten-containing ores. 1 z.p. f-ly, 1 tab., 1 ill.

The invention relates to the enrichment of minerals and can be used in the processing of tailings enrichment of tungsten-containing ores.

When processing tungsten-containing ores, as well as tailings for their enrichment, gravity, flotation, magnetic, as well as electrostatic, hydrometallurgical and other methods are used (see, for example, Burt P.O., with the participation of K. Mills. Gravitational enrichment technology. Translated from English. - M.: Nedra, 1990). So, for the preliminary concentration of useful components (mineral raw materials), photometric and lumometric sorting are used (for example, the Mount Carbine and King Island processing plants), enrichment in heavy media (for example, the Portuguese Panasquera factory and the English Hemerdan factory). ), jigging (especially poor raw materials), magnetic separation in a weak magnetic field (for example, to isolate pyrite, pyrrhotite) or high-intensity magnetic separation (to separate wolframite and cassiterite).

For the processing of tungsten-containing sludge, it is known to use flotation, in particular, wolframite in the PRC and at the Canadian Mount Plisad factory, and in some factories flotation completely replaced gravity enrichment (for example, the Jokberg factories, Sweden and Mittersil, Austria).

It is also known to use screw separators and screw locks for the enrichment of tungsten-containing ores, old dumps, stale tailings, and sludge.

So, for example, when processing old dumps of tungsten ore at the Cherdoyak factory (Kazakhstan), the initial dump material after crushing and grinding to a fineness of 3 mm was enriched in jigging machines, the undersize product of which was then cleaned on a concentration table. The technological scheme also included enrichment on screw separators, on which 75-77% WO 3 was extracted with an output of enrichment products of 25-30%. Screw separation made it possible to increase the extraction of WO 3 by 3-4% (see, for example, Anikin M.F., Ivanov V.D., Pevzner M.L. "Screw separators for ore dressing", Moscow, publishing house "Nedra ", 1970, 132 p.).

The disadvantages of the technological scheme for processing old dumps are the high load at the head of the process for the jigging operation, the insufficiently high extraction of WO 3 and the significant yield of enrichment products.

A known method of associated production of tungsten concentrate by processing the tailings of molybdenite flotation (factory "Climax molybdenum", Canada). Tailings containing tungsten are separated by means of a screw separation into tungsten tailings (light fraction), primary wolframite - cassiterite concentrate. The latter is subjected to hydrocyclone and the sludge discharge is sent to tailings, and the sand fraction is sent to the flotation separation of pyrite concentrate containing 50% S (sulfides) and its output to tailings. The chamber product of sulfide flotation is cleaned using a screw separation and/or cones to obtain waste pyrite-containing tailings and a wolframite-cassiterite concentrate, which is processed on concentration tables. At the same time, wolframite-cassiterite concentrate and tailings are obtained. The crude concentrate after dehydration is re-cleaned sequentially by cleaning it from iron using magnetic separation, flotation removal of monazite from it (phosphate flotation) and then dehydrated, dried, classified and separated using staged magnetic separation into a concentrate with a content of 65% WO 3 after stage I and 68% WO 3 after stage II. Also get a non-magnetic product - tin (cassiterite) concentrate containing ~35% tin.

This method of processing is characterized by disadvantages - complexity and multi-stage, as well as high energy intensity.

There is a known method for additional extraction of tungsten from the tailings of gravity enrichment (factory "Boulder", USA). The tailings of gravity enrichment are crushed, deslimed in a classifier, the sands of which are separated on hydraulic classifiers. The resulting classes are enriched separately on concentration tables. Coarse-grained tailings are returned to the grinding cycle, and fine tailings are thickened and re-enriched on slurry tables to obtain a finished concentrate, middling product for regrinding, and tailings sent for flotation. The rougher flotation concentrate is subjected to one cleaning. The original ore contains 0.3-0.5% WO 3 ; the extraction of tungsten reaches 97%, with about 70% of the tungsten being recovered by flotation. However, the content of tungsten in the flotation concentrate is low (about 10% WO 3) (see, Polkin S.I., Adamov E.V. Enrichment of non-ferrous metal ores. Textbook for universities. M., Nedra, 1983, 213 pp.)

The disadvantages of the technological scheme for the processing of tailings of gravity enrichment are the high load at the head of the process on the enrichment operation on concentration tables, multi-operation, low quality of the resulting concentrate.

A known method of processing scheelite-containing tailings in order to remove hazardous materials from them and process non-hazardous and ore minerals using an improved separation process (separation) (KR 20030089109, SNAE et al., 21.11.2003). The method includes the stages of homogenizing mixing of scheelite-containing tailings, introduction of the pulp into the reactor, “filtration” of the pulp with a screen to remove various foreign materials, subsequent separation of the pulp by screw separation, thickening and dehydration of non-metallic minerals to obtain a cake, drying the cake in a rotary dryer, crushing dry cake using a hammer mill operating in a closed cycle with a screen, separation of crushed minerals using a “micron” separator into fractions of small and coarse grains (granules), as well as magnetic separation of a coarse-grained fraction to obtain magnetic minerals and a non-magnetic fraction containing scheelite. The disadvantage of this method is multi-operation, the use of energy-intensive drying of wet cake.

There is a known method of additional extraction of tungsten from the tailings of the processing plant of the Ingichka mine (see A.B. Ezhkov, Kh.T. v.1, MISiS, M., 2001). The method includes preparation of the pulp and its desliming in a hydrocyclone (class removal - 0.05 mm), subsequent separation of the deslimed pulp in a cone separator, two-stage recleaning of the cone separator concentrate on concentration tables to obtain a concentrate containing 20.6% WO 3 , with an average recovery 29.06%. The disadvantages of this method are the low quality of the resulting concentrate and insufficiently high extraction of WO 3 .

The results of studies on the gravitational enrichment of the tailings of the Ingichkinskaya enrichment plant are described (see S.V. » // Mining Bulletin of Uzbekistan, 2008, No. 3).

The closest to the patented technical solution is a method for extracting tungsten from stale tailings of enrichment of tungsten-containing ores (Artemova O.S. Development of a technology for extracting tungsten from stale tailings of the Dzhida VMK. Abstract of the thesis of a candidate of technical sciences, Irkutsk State Technical University, Irkutsk, 2004 - prototype).

The technology for extracting tungsten from stale tailings according to this method includes the operations of obtaining a rough tungsten-containing concentrate and middling product, a gold-bearing product and secondary tailings using gravitational methods of wet enrichment - screw and centrifugal separation - and subsequent finishing of the obtained rough concentrate and middling product using gravity (centrifugal) enrichment and magnetic separation to obtain a standard tungsten concentrate containing 62.7% WO 3 with the extraction of 49.9% WO 3 .

According to this method, stale tails are subjected to primary classification with the release of 44.5% of the mass. into secondary tailings in the form of a fraction of +3 mm. The -3 mm tailings fraction is divided into -0.5 and +0.5 mm classes, and from the latter, a coarse concentrate and tails are obtained using screw separation. The fraction -0.5 mm is divided into classes -0.1 and +0.1 mm. From the +0.1 mm class, a coarse concentrate is isolated by centrifugal separation, which, like the coarse screw separation concentrate, is subjected to centrifugal separation to obtain a crude tungsten concentrate and a gold-bearing product. The tailings of the screw and centrifugal separation are crushed to -0.1 mm in a closed cycle with classification and then divided into classes -0.1 + 0.02 and -0.02 mm. The -0.02 mm class is removed from the process as secondary waste tailings. Class -0.1+0.02 mm is enriched by centrifugal separation to obtain secondary waste tailings and tungsten middlings, sent for refining by magnetic separation together with centrifugal separation concentrate, finely ground to -0.1 mm. In this case, a tungsten concentrate (magnetic fraction) and middlings (non-magnetic fraction) are obtained. The latter is subjected to magnetic separation II with the release of a non-magnetic fraction into secondary tailings and a tungsten concentrate (magnetic fraction), which is enriched sequentially by centrifugal, magnetic and again centrifugal separation to obtain a conditioned tungsten concentrate with a content of 62.7% WO 3 at an output of 0.14 % and recovery of 49.9%. At the same time, the tailings of centrifugal separations and the non-magnetic fraction are sent to the secondary tailings, the total output of which at the stage of finishing the crude tungsten concentrate is 3.28% with a content of 2.1% WO 3 in them.

The disadvantages of this method are the multi-operation process, which includes 6 classification operations, 2 regrinding operations, as well as 5 centrifugal operations and 3 magnetic separation operations using relatively expensive apparatus. At the same time, the refinement of the crude tungsten concentrate to the standard is associated with the production of secondary tailings with a relatively high content of tungsten (2.1% WO 3).

The objective of the present invention is to improve the method of processing tailings, including stale dump tailings for enrichment of tungsten-containing ores, to obtain a high-grade tungsten concentrate and a sulfide-containing product along with a decrease in the content of tungsten in secondary tailings.

The patented method for the complex processing of tailings for the enrichment of tungsten-containing ores includes the classification of tailings into fine and coarse fractions, screw separation of the fine fraction to obtain a tungsten product, repurification of the tungsten product, and finishing to obtain a high-grade tungsten concentrate, a sulfide-containing product and secondary waste tailings.

The method differs in that the resulting tungsten product is subjected to recleaning on a screw separator to obtain a rough concentrate and tailings, a rough concentrate is subjected to finishing on concentration tables to obtain a gravitational tungsten concentrate and tailings. The tails of the concentration table and the cleaning screw separator are combined and subjected to thickening, then the thickening discharge is fed to the classification stage at the head of the technological scheme, and the thickened product is enriched on a screw separator to obtain secondary waste tailings and a tungsten product, which is sent for cleaning. Gravity tungsten concentrate is subjected to flotation to obtain a high-grade standard tungsten concentrate (62% WO 3) and a sulfide-containing product, which is processed by known methods.

The method can be characterized by the fact that the tailings are classified into fractions, mainly +8 mm and -8 mm.

The technical result of the patented method is to increase the depth of processing while reducing the number of technological operations and the load on them due to the separation in the head of the process of the bulk of the initial tailings (more than 90%) into secondary tailings, using a simpler design and operation of energy-saving screw separation technology. This dramatically reduces the load on subsequent enrichment operations, as well as capital and operating costs, which ensures the optimization of the enrichment process.

The effectiveness of the patented method is shown on the example of complex processing of tailings of the Ingichkinskaya enrichment plant (see drawing).

Processing begins with the classification of tailings into small and large fractions with the separation of secondary tailings in the form of a large fraction. The fine fraction of the tailings is subjected to screw separation with the separation in the head of the technological process into the secondary tailings of the bulk of the original tailings (more than 90%). This makes it possible to drastically reduce the load on subsequent operations, capital costs and operating costs accordingly.

The resulting tungsten product is subjected to recleaning on a screw separator to obtain a crude concentrate and tailings. The crude concentrate is subjected to refinement on concentration tables to obtain gravity tungsten concentrate and tailings.

The tailings of the concentration table and the helical cleaning separator are combined and subjected to thickening, for example, in a thickener, mechanical classifier, hydrocyclone and other apparatuses. The thickening drain is fed to the classification stage at the head of the technological scheme, and the thickened product is enriched on a screw separator to obtain secondary tailings and a tungsten product, which is sent for cleaning.

Gravity tungsten concentrate is brought by flotation to high-grade conditional tungsten concentrate (62% WO 3 ) to obtain a sulfide-containing product.

Thus, high-grade (62% WO 3 ) conditioned tungsten concentrate is isolated from tungsten-containing tailings upon reaching a relatively high WO 3 recovery of ~49% and a relatively low tungsten content (0.04% WO 3 ) in secondary waste tailings.

The resulting sulfide-containing product is processed in a known manner, for example, it is used to produce sulfuric acid and sulfur, and is also used as a corrective additive in the production of cements.

High-grade conditioned tungsten concentrate is a highly liquid marketable product.

As follows from the results of the implementation of the patented method on the example of stale tailings for the enrichment of tungsten-containing ores of the Ingichkinskaya concentrator, its effectiveness is shown in comparison with the prototype method (see table). EFFECT: additional obtaining of a sulfide-containing product, reduction of the volume of fresh water consumed due to the creation of water circulation is provided. It creates the possibility of processing significantly poorer tailings (0.09% WO 3), a significant reduction in the content of tungsten in the secondary tailings (up to 0.04% WO 3). In addition, the number of technological operations has been reduced and the load on most of them has been reduced due to the separation of the bulk of the initial tailings (more than 90%) in the head of the technological process into secondary tailings, using a simpler and less energy-intensive screw separation technology, which reduces capital costs for the purchase of equipment and operating costs.

1. A method for the complex processing of tailings for the enrichment of tungsten-containing ores, including their classification into fine and coarse fractions, screw separation of the fine fraction to obtain a tungsten product, its cleaning and finishing to obtain a high-grade tungsten concentrate, a sulfide-containing product and secondary tailings, characterized in that the obtained after screw separation, the tungsten product is subjected to recleaning on a screw separator to obtain a crude tungsten concentrate, the resulting crude tungsten concentrate is subjected to finishing on concentration tables to obtain a gravity tungsten concentrate, which is subjected to flotation to obtain a high-grade conditioned tungsten concentrate and a sulfide-containing product, tails of a screw separator and a concentration table combined and subjected to thickening, the drain obtained after thickening is fed to the classification of tailings for the enrichment of tungsten-containing ores, and the subjected to enrichment on a screw separator to obtain secondary tailings and a tungsten product, which is sent for cleaning.