Development of technology for extracting tungsten from the stale tailings of the Dzhida VMC. Methods for processing tungsten concentrates Which factories process tungsten ores?

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State budgetary professional

educational institution of the Republic of Karelia

"Kostomuksha Polytechnic College"

Deputy Director of OD ___________________ Kubar T.S.

"_____"_________________________________2019

GRADUATE QUALIFYING WORK

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

Group student: Kuzich S.E.

4th year, group OPI-15 (41C)

Specialty 02/21/18

"Beneficiation of mineral resources"

Head of the research and development work: Volkovich O.V.

teacher special disciplines

Kostomuksha

2019

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

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

1.1 general characteristics tungsten ores………………………………….6

1.2 Economic assessment of tungsten ores……………………………………10

1. Technological scheme for beneficiation of tungsten ores using the example of Primorsky Mining and Processing Plant………………………………………………………..……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 creating safe working conditions in the workplace…………………………………………………………..…...30

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

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

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

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

Introduction

Mineral beneficiation - This is an industry that processes solid minerals with the intention of obtaining concentrates, i.e. products whose quality is higher than the quality of the original raw materials and meets the requirements for their further use in the national economy.Minerals are the basis National economy, and there is not a single industry where minerals or their processed products are not used.

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

IN last years Metal-ceramic hard alloys made on the basis of tungsten carbide are 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 quickly wearing parts of mechanisms (turbine blades, excavator equipment and etc.). Tungsten alloys with nickel and copper are used in the manufacture of protective screens against gamma rays in medicine.

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

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

The structure of tungsten consumption in the world is constantly changing. It is being replaced by other materials in some industries, but new areas of its application are emerging. Thus, in the first half of the 20th century, up to 90% of tungsten was spent on alloying steels. Currently, the industry is dominated by the production of tungsten carbide, and the use of tungsten metal is becoming increasingly important. IN Lately New opportunities are opening up for the use of tungsten as an environmentally friendly material. Tungsten can replace lead in the production of various ammunition, and can also be used in the manufacture of sports equipment, in particular golf clubs and balls. Developments in these areas are being carried out in the USA. In the future, tungsten should replace depleted uranium in the production of large-caliber ammunition. In the 1970s, when tungsten prices were around $170. for 1% WO content 3 per 1 ton of product, the USA and then some NATO countries replaced tungsten with depleted uranium in heavy ammunition, which, at the same technical specifications was significantly cheaper.

Tungsten, as a chemical element, belongs to the group of heavy metals and, from an environmental point of view, is classified as moderately toxic (Class II-III). The current source of tungsten pollution is environment are the processes of exploration, mining and processing (concentration and metallurgy) of tungsten-containing mineral raw materials. As a result of processing, such sources are unused solid waste, wastewater, and dusty tungsten-containing fine particles. Solid waste in the form of dumps and various tailings are formed during the enrichment of tungsten ores. Wastewater Processing plants are represented by tailings discharges, which are used as recycled water in grinding and flotation processes.

Graduation goal qualifying work : to justify the technological scheme for the enrichment of tungsten ores using the example of Primorsky GOK and the essence of dehydration processes in this technological scheme.

Tungsten is the most refractory metal, melting point 3380°C. And this determines its scope. It is also impossible to build electronics without tungsten; even the filament in a light bulb is tungsten.

And, naturally, the properties of the metal also determine the difficulties in obtaining it...

First, you need to find ore. These are just two minerals - scheelite (calcium tungstate CaWO 4) and wolframite (iron and manganese tungstate - FeWO 4 or MnWO 4). The latter has been known since the 16th century under the name "wolf's foam" - "Spuma lupi" in Latin, or "Wolf Rahm" in German. This mineral accompanies tin ores and interferes with the smelting of tin, turning it into slag. Therefore, it is possible to find it already in antiquity. Rich tungsten ores usually contain 0.2 - 2% tungsten. Tungsten was actually discovered in 1781.

However, this is the easiest thing to find in tungsten mining.
Next, the ore needs to be enriched. There are a bunch of methods and they are all quite complex. First of all, of course. Then - magnetic separation (if we have wolframite with iron tungstate). Next is gravitational separation, because the metal is very heavy and the ore can be washed, much like when mining gold. Nowadays they still use electrostatic separation, but it is unlikely that the method will be useful to the endangered person.

So, we have separated the ore from the gangue. If we have scheelite (CaWO 4), then we can skip the next step, but if we have wolframite, then we need to turn it into scheelite. To do this, tungsten is extracted soda solution under pressure and at elevated temperature (the process takes place in an autoclave), followed by neutralization and precipitation in the form of artificial scheelite, i.e. calcium tungstate.
It is also possible to sinter wolframite with an excess of soda, then we obtain tungstate not of calcium, but of sodium, which for our purposes is not so significant (4FeWO 4 + 4Na 2 CO 3 + O 2 = 4Na 2 WO 4 + 2Fe 2 O 3 + 4CO 2).

The next two stages are leaching with water CaWO 4 -> H 2 WO 4 and decomposition with hot acid.
You can take different acids - hydrochloric (Na 2 WO 4 + 2HCl = H 2 WO 4 + 2NaCl) or nitric.
As a result, tungsten acid is isolated. The latter is calcined or dissolved in an aqueous solution of NH 3, from which paratungstate is crystallized by evaporation.
As a result, it is possible to obtain the main raw material for the production of tungsten - WO 3 trioxide with good purity.

Of course, there is also a method for producing WO 3 using chlorides, when tungsten concentrate is treated with chlorine at elevated temperatures, but this method will not be simple for the outsider.

Tungsten oxides can be used in metallurgy as an alloying additive.

So, we have tungsten trioxide and there is only one step left - reduction to metal.
There are two methods here - reduction with hydrogen and reduction with carbon. In the second case, the coal and the impurities it always contains react with tungsten, forming carbides and other compounds. Therefore, tungsten comes out “dirty”, brittle, and for electronics it is pure that is very desirable, because having only 0.1% iron, tungsten becomes brittle and it is impossible to draw the thinnest wire for incandescent filaments from it.
The technical process with coal has another drawback - high temperature: 1300 - 1400°C.

However, production with hydrogen reduction is also not a gift.
The reduction process takes place in special tube furnaces, heated in such a way that as it moves through the tube, the “boat” of WO3 passes through several temperature zones. A stream of dry hydrogen comes towards it. Recovery occurs in both “cold” (450...600°C) and “hot” (750...1100°C) zones; in “cold” ones – to the lower oxide WO 2, then – to the elemental metal. Depending on the temperature and duration of the reaction in the “hot” zone, the purity and grain size of the powdered tungsten released on the walls of the “boat” change.

So, we have obtained pure tungsten metal in the form of a tiny powder.
But this is not yet an ingot of metal from which something can be made. The metal is produced by powder metallurgy. That is, it is first pressed, sintered in a hydrogen atmosphere at a temperature of 1200-1300 °C, then passed through it electricity. The metal is heated to 3000 °C, and sintering occurs into a monolithic material.

However, we rather need not ingots or even rods, but thin tungsten wire.
As you yourself understand, here again everything is not so simple.
Wire drawing is carried out at a temperature of 1000°C at the beginning of the process and 400-600°C at the end. In this case, not only the wire, but also the die is heated. Heating is carried out by a gas burner flame or an electric heater.
In this case, after drawing, the tungsten wire is coated with graphite lubricant. The surface of the wire must be cleaned. Cleaning is carried out using annealing, chemical or electrolytic etching, and electrolytic polishing.

As you can see, the task of producing a simple tungsten filament is not as simple as it seems. And only the basic methods are described here; there are probably a lot of pitfalls there.
And, of course, even now tungsten is not a cheap metal. Now one kilogram of tungsten costs more than $50, the same molybdenum is almost two times cheaper.

Actually, there are several uses for tungsten.
Of course, the main ones are radio and electrical engineering, where tungsten wire goes.

The next one is the production of alloy steels, which are distinguished by their particular hardness, elasticity and strength. Added together with chromium to iron, it produces so-called high-speed steels, which retain their hardness and sharpness even when heated. They are used to make cutters, drills, milling cutters, as well as other cutting and drilling tools (in general, drilling tools contain a lot of tungsten).
Tungsten-rhenium alloys are interesting - they are used to make high-temperature thermocouples that operate at temperatures above 2000°C, although only in an inert environment.

Well, and one more thing interesting application- These are tungsten welding electrodes for electric welding. Such electrodes are non-consumable and it is necessary to supply additional metal wire to the welding site to provide a weld pool. Tungsten electrodes are used in argon arc welding - for welding non-ferrous metals such as molybdenum, titanium, nickel, as well as high-alloy steels.

As you can see, tungsten production is not for ancient times.
And why is tungsten there?
Tungsten can only be obtained with the construction of electrical engineering - with the help of electrical engineering and for electrical engineering.
No electricity means no tungsten, but you don’t need it either.

The chemical element is tungsten.

Before describing the production of tungsten, it is necessary to take a short excursion into history. The name of this metal is translated from German as “wolf’s 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, turning into foamy slag, “like a wolf devouring its prey.”

The metaphor caught on, 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 the ore later named after him (scheelite).

Swedish chemist Scheele, who discovered tungsten.

Industrial production of tungsten metal can be divided into 3 stages:

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

Ore beneficiation

Tungsten does not occur in a free state in nature; it is present only in various compounds.

• wolframites
• scheelites

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

1. Beneficiation begins with crushing and grinding the rock. The material is then sent for further processing, the methods of which depend on the type of ore. Enrichment of wolframite ores is usually carried out using the gravitational method, the essence of which is to use the combined forces of gravity and centrifugal force; minerals are separated according to chemical and physical properties - density, particle size, wettability. This way, the waste rock is separated, and the concentrate is brought to the required purity using magnetic separation. The wolframite content 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 at the outlet can be up to 90%. Ores can also be complex, containing wolframites and scheelites at the same time. To enrich them, methods combining gravitational and flotation schemes are used.
   
   If further purification of the concentrate to established standards is necessary, various procedures are used depending on the type of impurities. To reduce phosphorus impurities, scheelite concentrates are processed in the cold hydrochloric acid, at the same time calcite and dolomite are removed. To remove copper, arsenic, and bismuth, roasting followed by treatment with acids is used. There are other cleaning methods.

Several different methods are used to convert tungsten from a concentrate into a soluble compound.

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

The main result of various enrichment methods is the production of tungsten trioxide. Further, it is he who goes into the production of metal 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.

Tungsten Recovery

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

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

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

Obtaining monolithic metal

If the first two stages industrial production Since tungsten is well known to metallurgists and has been used for a very long time, obtaining a monolith from powder required the development of a special technology. Most metals are obtained by simple melting and then cast into molds; with tungsten, due to its main property - refractoriness - such a procedure is impossible. The method of producing 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 electric current. Instead of conventional smelting, several steps must be taken to obtain tungsten metal. At the first of them, the powder is pressed into special bars. Then these posts are subjected to a sintering procedure, and this is done in two stages:

1. 1. First, at temperatures up to 1300ºC, the rod is pre-sintered to increase its strength. The procedure is carried out in a special sealed oven 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 rod. After this stage, the headstock is significantly strengthened, 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 secured 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 bars 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 bar is first welded, it is used to calibrate the welding mode. The duration of welding depends on the size of the post and usually ranges from 15 minutes to an hour. This stage, like the first, also leads to a reduction in the size of the stack.

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

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

Production of tungsten products

Obtained from the original ore after the three production stages described, monolithic tungsten has a unique set of properties. In addition to refractoriness, it is characterized by very high stability of geometric dimensions, preservation of strength at high temperatures and the absence of internal stress. Tungsten also has good ductility and malleability. Further production most often involves drawing out wire. These are technologically relatively simple processes.

1. The blanks enter a rotary forging machine, where the material is compressed.
2. Then the drawing method produces wire of various diameters (drawing is drawing a rod using special equipment through tapering holes). This way you can obtain 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 filaments electric lamps even before the development of a method for producing malleable tungsten. The Russian scientist Lodygin, who had previously patented the principle of using a filament for a lamp, in the 1890s proposed using tungsten wire twisted into a spiral as such a filament. How did you get tungsten for such wires? First, a mixture of tungsten powder with some kind of 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. The result was a rather fragile wire, straight sections of which were attached to the electrodes of the lamp. There were attempts to obtain compact metal using other methods, however, in all cases, the fragility of the threads remained critically high. After the work of Coolidge and Fink, the production of tungsten wire gained a solid technological basis, 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 approximately 41 thousand tons per year (Russia, for comparison, produces 3.5 thousand tons). An important factor currently is the processing of secondary raw materials, usually scrap tungsten carbide, shavings, sawdust and tungsten powder residues; such processing provides about 30% of global tungsten consumption.

Filaments from burnt-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. According to experts, the use of tungsten in this sector will decrease by 5% per year in the coming years. The demand for tungsten as a whole is not decreasing; the decline in applicability in one sector is compensated by growth in others, including innovative industries.

The invention relates to a method complex processing tailings from the enrichment of tungsten-containing ores. The method includes their classification into small and large fractions, screw separation of the fine fraction to obtain a tungsten product and its cleaning. In this case, re-cleaning is carried out on a screw separator to obtain a rough tungsten concentrate, which is refined 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. The tailings of the screw separator and the concentration table are combined and subjected to thickening. In this case, the waste 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 in a screw separator to obtain secondary waste tailings and a tungsten product, which is sent for cleaning. The technical result is to increase the depth of processing of tungsten-containing ore tailings. 1 salary files, 1 table, 1 ill.

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

When processing tungsten-containing ores, as well as their tailings, gravitational, flotation, magnetic, as well as electrostatic, hydrometallurgical and other methods are used (see, for example, Bert P.O., with the participation of K. Mills. Gravity enrichment technology. Translated from English. - M.: Nedra, 1990). So, for preliminary concentration useful components(mineral raw materials) photometric and lumometric sorting are used (for example, the Mount Carbine and King Island processing plants), enrichment in difficult environments (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, for the separation of pyrite, pyrrhotite) or high-intensity magnetic separation (for the separation of wolframite and cassiterite).

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

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

For example, when processing old dumps of tungsten ore at the Cherdoyak factory (Kazakhstan), the initial dump material, after crushing and grinding to a size of 3 mm, was subjected to enrichment on jiggers, the under-sieve product of which was then cleaned on a concentration table. The technological scheme also included enrichment in screw separators, in which 75-77% of WO 3 was recovered with a yield 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, Nedra publishing house ", 1970, 132 pp.).

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

There is a known method for the associated production of tungsten concentrate by processing molybdenite flotation tailings (Climax Molybdenum factory, Canada). Tailings containing tungsten are separated using screw separation into tungsten waste sludge (light fraction), primary wolframite - cassiterite concentrate. The latter is subjected to hydrocyclonation and the sludge discharge is sent to the waste tailings, and the sand fraction is sent to the flotation separation of pyrite concentrate containing 50% S (sulfides) and discharged into the waste tailings. The chamber product of sulfide flotation is purified using screw separation and/or cones to obtain waste pyrite-containing tailings and wolframite-cassiterite concentrate, which is processed on concentration tables. In this case, wolframite-cassiterite concentrate and waste tailings are obtained. After dehydration, the crude concentrate is cleaned sequentially by purifying it from iron using magnetic separation, removing monazite from it by flotation (phosphate flotation) and then dewatering, drying, classifying and separating using stage magnetic separation into a concentrate containing 65% WO 3 after stage I and 68% WO 3 after stage II. A non-magnetic product is also obtained - tin (cassiterite) concentrate containing ~35% tin.

This processing method has disadvantages - complexity and multi-stage nature, as well as high energy intensity.

There is a known method for additional extraction of tungsten from gravity enrichment tailings (Boulder plant, USA). Gravity enrichment tailings are further crushed and deslimed in a classifier, the sands of which are separated using hydraulic classifiers. The resulting classes are enriched separately on concentration tables. Coarse tailings are returned to the grinding cycle, and fine tailings are thickened and re-enriched on slurry tables to produce a finished concentrate, middlings sent to regrinding, and tailings sent to flotation. The main flotation concentrate is subjected to one cleaning. The original ore contains 0.3-0.5% WO 3; Tungsten recovery reaches 97%, with about 70% of tungsten recovered by flotation. However, the tungsten content 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 processing 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 the resulting concentrate.

There is a known method for processing scheelite-containing tailings in order to remove hazardous materials from them and process non-hazardous and ore minerals using an improved separation process (KR 20030089109, CHAE et al., 11/21/2003). The method includes the stages of homogenizing mixing of scheelite-containing tailings, introduction of the pulp into the reactor, “filtration” of the pulp using a screen to remove various foreign materials, subsequent separation of the pulp by screw separation, thickening and dehydration of non-metallic minerals to produce a cake, drying the cake in a rotary dryer, crushing the dry cake using a hammer crusher operating in a closed cycle with a screen, separation of crushed minerals using a “micron” separator into fractions of fine and coarse grains (granules), as well as magnetic separation of the coarse-grained fraction to obtain magnetic minerals and a non-magnetic fraction containing scheelite. The disadvantage of this method is the multi-operation nature and the use of energy-intensive drying of the wet cake.

There is a known method for additional extraction of tungsten from waste tailings processing plant Ingichki mine (see A.B. Ezhkov, Kh.T. Sharipov, K.L. Belkov “Involvement in the processing of stale tungsten-containing tailings of the Ingichki mine.” Abstracts of the III Congress of Concentrators of the CIS Countries, vol. 1, MISiS, M., 2001). The method includes preparing the pulp and desliming it in a hydrocyclone (removal class - 0.05 mm), subsequent separation of the deslimed pulp on a cone separator, two-stage re-cleaning 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 WO 3 extraction.

The results of research on the gravitational enrichment of tailings from the Ingichkinsky enrichment plant are described (see S.V. Rudnev, V.A. Potapov, N.V. Salikhova, A.A. Kanzel “Research on the selection of the optimal technological scheme for the gravitational enrichment of man-made formations at the Ingichkinsky enrichment plant "//Mining Bulletin of Uzbekistan, 2008, No. 3).

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

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

According to this method, stale tailings are subjected to primary classification with the release of 44.5% of the mass. into secondary tailings in the form of a +3 mm fraction. The tailings fraction with a particle size of -3 mm is divided into classes -0.5 and +0.5 mm, and from the latter, coarse concentrate and tailings are obtained using screw separation. The -0.5 mm fraction is divided into classes -0.1 and +0.1 mm. From the +0.1 mm class, a coarse concentrate is separated using centrifugal separation, which, like the coarse concentrate of screw separation, is subjected to centrifugal separation to obtain rough tungsten concentrate and a gold-containing product. The tailings of screw and centrifugal separation are further 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 grade is removed from the process as secondary tailings. Class -0.1+0.02 mm is enriched by centrifugal separation to produce secondary tailings and tungsten middlings, sent for finishing by magnetic separation along with the centrifugal separation concentrate, ground to a size of -0.1 mm. In this case, tungsten concentrate (magnetic fraction) and middling product (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 tungsten concentrate (magnetic fraction), which is enriched sequentially by centrifugal, magnetic and again centrifugal separation to obtain standard tungsten concentrate containing 62.7% WO 3 with a yield of 0.14 % and recovery 49.9%. In this case, the tailings of centrifugal separations and the non-magnetic fraction are sent to secondary tailings, the total yield of which at the stage of finishing the rough tungsten concentrate is 3.28% with a content of 2.1% WO 3.

The disadvantages of this method are multi-operation technological process, including 6 classification operations, 2 additional grinding operations, as well as 5 centrifugal and 3 magnetic separation operations using relatively expensive devices. At the same time, finishing the crude tungsten concentrate to the required standard is associated with the production of secondary waste tailings with a relatively high tungsten content (2.1% WO 3).

The objective of the present invention is to improve the method of processing enrichment tailings, including stale tailings from the enrichment of tungsten-containing ores, to obtain high-grade tungsten concentrate and an associated sulfide-containing product while reducing the tungsten content in the secondary waste tailings.

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

The method differs in that the resulting tungsten product is subjected to re-cleaning on a screw separator to obtain rough concentrate and tailings, the rough concentrate is subjected to finishing on concentration tables to obtain gravitational tungsten concentrate and tailings. The tailings 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 subjected to enrichment on a screw separator to obtain secondary tailings and a tungsten product, which is sent for cleaning. The gravity tungsten concentrate is subjected to flotation to obtain a high-grade 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 with a size of +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 at the head of the process of the bulk of the initial tailings (more than 90%) into secondary waste tailings, using energy-saving screw separation technology that is simpler in design and operation. This allows you to dramatically reduce the load on subsequent enrichment operations, as well as capital expenditures and operating costs, which ensures optimization of the enrichment process.

The effectiveness of the patented method is shown using the example of complex processing of tailings from the Ingichkinsky enrichment plant (see drawing).

Processing begins with the classification of tailings into small and large fractions with the separation of secondary waste tailings in the form of a large fraction. The fine fraction of the tailings is subjected to screw separation with the separation of the bulk of the original tailings (more than 90%) at the head of the technological process into secondary waste tailings. This allows for a correspondingly dramatic reduction in downstream workload, capital costs and operating costs.

The resulting tungsten product is subjected to re-cleaning using a screw separator to obtain rough concentrate and tailings. The rough concentrate is subjected to finishing on concentration tables to obtain gravity tungsten concentrate and tailings.

The tailings of the concentration table and the cleaning screw separator are combined and subjected to thickening, for example, in a thickener, mechanical classifier, hydrocyclone and other devices. The condensation discharge is fed to the classification stage at the head of the technological scheme, and the condensed product is subjected to enrichment in a screw separator to obtain secondary tailings and a tungsten product, which is sent for cleaning.

The gravity tungsten concentrate is brought by flotation to a high-grade 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 achieving a relatively high WO 3 extraction of ~49% and a relatively low tungsten content (0.04% WO 3 ) in the secondary waste tailings.

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

High-grade tungsten concentrate is a highly liquid commercial product.

As follows from the results of implementing the patented method using the example of stale tailings from the enrichment of tungsten-containing ores from the Ingichkinsky concentrating plant, its effectiveness is shown in comparison with the prototype method (see table). Provided additional receipt sulfide-containing product, reducing the volume of fresh water consumed by creating a water cycle. It creates the possibility of processing significantly poorer tailings (0.09% WO 3), a significant reduction in the tungsten content in secondary waste 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 at the head of the technological process of the bulk of the initial tailings (more than 90%) into secondary waste 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 complex processing of tailings from the enrichment of tungsten-containing ores, including their classification into small and large fractions, screw separation of the fine fraction to produce a tungsten product, its re-cleaning and finishing to produce high-grade tungsten concentrate, sulfide-containing product and secondary waste tailings, characterized in that the resulting after screw separation, the tungsten product is subjected to re-cleaning on a screw separator to obtain rough tungsten concentrate, the resulting rough tungsten concentrate is subjected to finishing on concentration tables to obtain gravity tungsten concentrate, which is subjected to flotation to obtain high-grade conditioned tungsten concentrate and sulfide-containing product, tailings of the screw separator and concentration table are combined and subjected to thickening, the resulting waste after thickening is fed to the classification of tailings for the enrichment of tungsten-containing ores, and the thickened product is subjected to enrichment in a screw separator to obtain secondary waste tailings and a tungsten product, which is sent for cleaning.

Tungsten minerals and ores

From tungsten minerals practical significance have minerals of the wolframite and scheelite group.

Wolframite (xFeWO4 yMnWO4) is an isomorphic mixture of iron and manganese tungstates. If a mineral contains more than 80% iron, the mineral is called ferberite. If the mineral contains more than 80% manganese, then the mineral is called hubernite.

Scheelite CaWO4 is almost pure calcium tungstate.

Tungsten ores contain small amounts of tungsten. The minimum WO3 content at which their processing is advisable. is 0.14-0.15% for large deposits and 0.4-0.5% for small deposits. In ores, tungsten is accompanied by tin in the form of cassiterite, as well as the minerals molybdenum, bismuth, arsenic and copper. The main gangue rock is silica.

Tungsten ores undergo beneficiation. Wolframite ores are enriched using the gravity method, and scheelite ores are enriched by flotation.

Tungsten ore enrichment schemes are varied and complex. They combine gravitational enrichment with magnetic separation, flotation gravity and flotation. By combining various enrichment methods, concentrates containing up to 55-72% WO3 are obtained from ores. The extraction of tungsten from ore into concentrate is 82-90%.

Composition tungsten concentrates fluctuates within the following limits,%: WO3-40-72; MnO-0.008-18; SiO2-5-10; Mo-0.008-0.25; S-0.5-4; Sn-0.03-1.5; As-0.01-0.05; P-0.01-0.11; Cu-0.1-0.22.

Technological schemes for processing tungsten concentrates are divided into two groups: alkaline and acidic.

Methods for processing tungsten concentrates

Regardless of the method of processing wolframite and scheelite concentrates, the first stage of their processing is opening, which is the transformation of tungsten minerals into easily soluble chemical compounds.

Wolframite concentrates are opened by sintering or fusion with soda at a temperature of 800-900°C, which is based on chemical reactions:

4FeWO4 + 4Na2CO3 + O2 = 4Na2WO4 + 2Fe2O3 +4CO2 (1)

6MnWO4 + 6Na2CO3 + O2 = 6Na2WO4 + 2Mn3O4 +6CO2 (2)

When sintering scheelite concentrates at a temperature of 800-900°C, the following reactions occur:

CaWO4 + Na2CO3 = Na2WO4+ CaCO3 (3)

CaWO4 + Na2CO3 = Na2WO4+ CaO + CO2 (4)

In order to reduce soda consumption and prevent the formation of free calcium oxide, silica is added to the charge to bind calcium oxide into a sparingly soluble silicate:

2CaWO4 + 2Na2CO3 + SiO2 = 2Na2WO4+ Ca2SiO4 + CO2 (5)

Sintering of scheelite concentrate with soda and silica is carried out in drum furnaces at a temperature of 850-900°C.

The resulting cake (alloy) is leached with water. During leaching, sodium tungstate Na2WO4 and soluble impurities (Na2SiO3, Na2HPO4, Na2AsO4, Na2MoO4, Na2SO4) and excess soda pass into the solution. Leaching is carried out at a temperature of 80-90°C in steel reactors with mechanical stirring, operating in batch mode, or in continuous drum rotary kilns. The recovery of tungsten into the solution is 98-99%. The solution after leaching contains 150-200 g/l WO3. The solution is filtered, and after separating the solid residue, it is sent for purification from silicon, arsenic, phosphorus and molybdenum.

Purification from silicon is based on the hydrolytic decomposition of Na2SiO3 by boiling a solution neutralized at pH = 8-9. Neutralization of excess soda in the solution is carried out with hydrochloric acid. As a result of hydrolysis, slightly soluble silicic acid is formed:

Na2SiO3 + 2H2O = 2NaOH + H2SiO3 (6)

To remove phosphorus and arsenic, the method of precipitation of phosphate and arsenate ions in the form of poorly soluble ammonium-magnesium salts is used:

Na2HPO4 + MgCl2+ NH4OH = Mg(NH4)PO4 + 2NaCl + H2O (7)

Na2HAsO4 + MgCl2+ NH4OH = Mg(NH4)AsO4 + 2NaCl + H2O (8)

Purification from molybdenum is based on the decomposition of molybdenum sulfosalt, which is formed when sodium sulfide is added to a solution of sodium tungstate:

Na2MoO4 + 4NaHS = Na2MoS4 + 4NaOH (9)

Upon subsequent acidification of the solution to pH = 2.5-3.0, the sulfosalt is destroyed with the release of slightly soluble molybdenum trisulfide:

Na2MoS4 + 2HCl = MoS3 + 2NaCl + H2S (10)

Calcium tungstate is first precipitated from a purified solution of sodium tungstate using CaCl2:

Na2WO4 + CaCl2 = CaWO4 + 2NaCl. (eleven)

The reaction is carried out in a boiling solution containing 0.3-0.5% alkali

while stirring with a mechanical stirrer. The washed sediment of calcium tungstate in the form of a pulp or paste is subjected to decomposition with hydrochloric acid:

CaWO4 + 2HCl = H2WO4 + CaCl2 (12)

During decomposition, the high acidity of the pulp is maintained at about 90-120 g/l HCl, which ensures the separation of impurities of phosphorus, arsenic and partly molybdenum, which are soluble in hydrochloric acid, from the tungstic acid sediment.

Tungstic acid can also be obtained from a purified solution of sodium tungstate by direct precipitation with hydrochloric acid. When the solution is acidified with hydrochloric acid, H2WO4 precipitates as a result of hydrolysis of sodium tungstate:

Na2WO4 + 2H2O = 2NaOH + H2WO4 (11)

The alkali formed as a result of the hydrolysis reaction reacts with hydrochloric acid:

2NaOH + 2HCl = 2NaCl + 2H2O (12)

The addition of reactions (8.11) and (8.12) gives the total reaction of precipitation of tungstic acid with hydrochloric acid:

Na2WO4 + 2HCl = 2NaCl + H2WO4 (13)

However, in this case, great difficulties arise in washing the sediment from sodium ions. Therefore, at present, the latter method of tungstic acid deposition is used very rarely.

The technical tungstic acid obtained by precipitation contains impurities and therefore needs to be purified.

The most widely used method is the ammonia method for purifying technical tungsten acid. It is based on the fact that tungstic acid is highly soluble in ammonia solutions, while a significant part of the impurities it contains are insoluble in ammonia solutions:

H2WO4 + 2NH4OH = (NH4)2WO4 + 2H2O (14)

Ammonia solutions of tungstic acid may contain impurities of molybdenum and alkali metal salts.

Deeper cleaning is achieved by isolating large crystals of ammonium paratungstate from the ammonia solution, which are obtained by evaporating the solution:

12(NH4)2WO4 = (NH4)10W12O41 5H2O + 14NH3 + 2H2O (15)

tungsten acid anhydride precipitation

Deeper crystallization is impractical to avoid contamination of the crystals with impurities. From the mother liquor, enriched with impurities, tungsten is precipitated in the form of CaWO4 or H2WO4 and returned to the previous stages.

Paratungstate crystals are squeezed out on filters, then in a centrifuge, washed cold water and dry.

Tungsten oxide WO3 is obtained by calcining tungstic acid or paratungstate in a rotating tubular furnace with a stainless steel pipe and heated by electricity at a temperature of 500-850oC:

H2WO4 = WO3 + H2O (16)

(NH4)10W12O41 5H2O = 12WO3 + 10NH3 +10H2O (17)

In tungsten trioxide intended for the production of tungsten, the WO3 content must be no lower than 99.95%, and for the production of hard alloys - no lower than 99.9%