RU2476610C2 - Extraction method of metals from metal-containing mineral raw material - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method involves crushing of raw material, its heaping in the form of a pile, pre-treatment of raw material in the pile, treatment of the pile with a leaching solution, dilution of metals and obtaining of productive solution with removal of metals from it. At that, pre-treatment is performed by supplying separate solutions or mixture of solutions containing surface active substance and hypochlorite to the pile. Treatment with the leaching solution is performed by means of the solution obtained by mixing in the pile volume at supply to it of separate solutions or mixture of solutions containing hypochlorite, surface-active substance and/or mineral acid. In the leaching solution there used are mixtures of mineral acids or in-series introduced mineral acids. Supply points of the above solutions to the pile can be different.

EFFECT: increasing the efficiency of the process cycle at reduction of costs and emission of hazardous gases.

5 cl, 9 tbl, 6 ex

Description

The invention relates to the metallurgical and mining industries, mainly to heap leaching of metals from metal-containing mineral raw materials, such as ores and / or ore concentrates, industrial metal-containing waste: dumps, sludges, etc., and can be used in metallurgical and mining enterprises of non-ferrous metallurgy. The invention can be used in mining by underground or heap leaching from crushed metal-containing mineral raw materials, in particular from slag and clinker of metallurgical industries. Distinctive features of such raw materials: a relatively low content of non-ferrous and noble metals with a simultaneously high concentration of compounds of silicon, aluminum, iron and calcium in the form of resistant glassy structures that arose at high temperatures. This makes it difficult to extract valuable and precious metals.

Numerous examples in the literature describe the use of nitrogen-containing heterocyclic aromatic compounds for the direct extraction of precious metals, in particular gold and platinum group metals (Patent US 4654145 03/31/1987, C22B 3/34), where chloride solutions are used, and quinolines are used as active extractants. Only gold is directly extracted, and platinoids are then extracted from the organic phase. This method is not suitable for processing metallurgical waste. A known method for the extraction of gold and silver (Patent RU 2027785, 1991.08.01), which allows to increase the selectivity of the extraction of precious metals and simplify the process. Essence: the initial gold-containing product is crushed, mixed with a solution of sodium or potassium ferrocyanide. Processing is carried out in an autoclave at 100-180 ° C and a compressed air pressure of 5-20 atm. This method of periodic action is not applicable for the integrated processing of metallurgical waste. A hydrometallurgical method for the extraction of rare metals is also known (patent US 4752412, С22В 3/44, С22В 3/00, 06/21/1988), which consists in the fact that pre-ground raw materials are placed in an open vessel containing a stirred, heated to boiling (preferably up to 82 ° C) an acidic aqueous solution with an acidity pH of 3 or lower, containing acid taken from the series: nitric, hydrochloric, sulfuric, phosphoric, hydrofluoric, acetic. The process is carried out with continuous bubbling into the reaction mixture of a mixture of gaseous oxidizing agents introduced from outside from a UV-ozone generator, obtained by irradiating a mixture of molecular oxygen and water vapor with high pressure mercury lamps. Then, to isolate the rare metals oxidized in an acidic solution from the matrix and form a productive solution containing rare metal complexes, increase the pH of the reaction mixture to 11 by adding limestone and alkali and complexing agents for rare metals taken from the series cyanide, hypochlorite are introduced into the reaction mixture , thiocarbamate, thiourea or iron (II) - hypochlorite, which form water-soluble chelates with oxidized rare metals. After a certain time of leaching of rare metals under the indicated conditions and the formation of a mother liquor saturated with chelate complexes of rare metals, the supply of oxidizing agents is stopped, the mother liquor is separated from insoluble materials and useful components are extracted from the mother liquor using standard technologies. Oxidizing agents are introduced into the reaction mixture as a gas phase. The efficiency of such a process in an open vessel is not high due to the low speed of diffuse exchange and the low speed of establishing equilibrium at the gas-liquid interface. Major components, such as ozone and oxygen, are poorly soluble in aqueous liquids. In addition, when implementing the method, there are large irretrievable losses of gaseous oxidizing agents under conditions of gas sparging through the liquid reaction mixture in an open vessel and due to the high temperature of the process. This process control also does not provide a sufficient concentration of oxidizing agents on the reaction surface of the refractory particles of the matrix of raw materials in aqueous solution due to diffuse restrictions on the solution-matrix interface. Reduces the efficiency of the process, increases the number of operations and the duration of the process, the proposed separate maintenance of the oxidation of the matrix and rare metals in an acidic environment and the subsequent, already in an alkaline environment, obtaining a mother liquor and soluble complexes of rare metals. There is a risk of clogging of micropores and microcracks on the surface of the resistant particles of the raw material with the resulting calcium sulfate, which reduces the extraction of valuable components. This method does not provide the opening of components resistant to peroxide oxidation. The method is cost-effective only for rare metals and at their elevated concentrations, which is rare. There are also known methods of heap leaching of ores, including the preparation of ore, the formation of its stack and its irrigation with a leach solution penetrating the stack, dissolving the metal and draining the productive solution. As leaching solutions, weak solutions of sulfuric acid, a solution of iron sulfate and sulfuric acid, soda solution, sodium cyanide, etc. are used (see Kalabin A.I. Extraction of minerals by underground leaching - M .: Atomizdat, 1969, S.95- 319; Rysev V.P., Sadykov R.Kh., Fazlullin M.I. Experience in heap leaching of gold - Mining Journal. - 1994. - No. 12 - P.8-10). Their modification is a method of heap leaching of ores, including crushing ore, pelletizing ore (cement, lime, polymers, natural compounds such as humic acids, etc.), dumping ore in the form of a trapezoidal stack, irrigating the ore stack with a leaching solution (for gold-bearing ores - cyanide, e.g. sodium cyanide concentration of 0.2 ... 0.4 g / l with the irrigation density of 150 ... 170 l / (m ² · day)), infiltration of the solution into an array of stacks of metal dissolution and drainage rich solvent followed by sorption on activated at ol or zinc chips (. cm Dementiev VE, AP Tatarinov, Gudkov S. Main aspects of the technology heap leaching of gold ores Mining Journal -.. 2001. - №5 - S.53-55). The disadvantages of these methods: a decrease in the rate of leaching and completeness of metal extraction due to the clogging of the pore space in the lower part of the stack due to the segregation of pieces of ore and the transfer of small particles (clay, sludge) from the upper to the lower part of the stack. At low outside temperatures, the leach rate also decreases sharply due to an increase in the viscosity of the leach solutions. A known method for the extraction of metals from ores containing natural sorbents: charcoal, silica gel, alumina, zeolites, etc. (Patent RU 2118384, IPC ⁶ C22B 3/04, 08/27/1998), which includes preparing the ore for leaching, feeding the leaching solution in ore, the collection of the productive solution and the deposition of metal from the productive solution on ion exchangers. The key to this method is the use of surface-active substances (surfactants) precisely to prevent the re-deposition of gold ions on the surface of natural sorbents contained in the ore. To extract metals using this method, productive solutions are passed through ion-exchange synthetic resin-ion exchangers, therefore, the method poses limitations for surfactants, namely: the length of the carbon chains of surfactants is greater than the length of the carbon chains of natural sorbents contained in the ore, but less than the length of the carbon chains of ion exchangers on which metal is precipitated from a productive solution. As a result of this, gold can pass from the productive solution to ion exchangers, from which the metal is then obtained by known technology. The disadvantages of this method: the need for a joint selection of ion exchangers, surfactants with their own range of action, and other components of the leach solution, high consumption and high cost of a number of ion exchangers and surfactants that meet these requirements, the difficulties of using this method for large-capacity complex processing of raw materials containing different metals. In addition, surfactant molecules with a long hydrocarbon chain can not only lower surface tension, but also effectively hydrophobize the solid hydrophilic surface of clay particles and metal, ensuring the distribution of the hydrocarbon film on the surfaces of metal and clay mineral rock. As a result, a layer of non-polar liquid may appear at the “mineral particle-metal” interface, which has a low cohesion function determined by non-specific dispersion interactions. This blocks the leaching of metals, especially those already present in the rock in the form of microinclusions ("micro-rings"), which is typical of precious metals. The efficiency of their extraction can decrease dramatically. In industrial metallurgical wastes, for example, in clinker of metallurgical production, industrial ashes in the form of such inclusions, non-precious metals are often present: iron and non-ferrous metals. This method is designed to extract gold into ion exchangers, and the use for the complex processing of large-scale waste is difficult. There is also known a method for the extraction of precious metals, including the processing of materials with a reverse leach solution of a mixture of hydrochloric and sulfuric acids with the addition of hydrogen peroxide as an oxidizing agent, followed by processing of the productive solution ("Rh, PtandPdRecoveryfromNewandApentAutomativeCatalysts" // WuKooYinget, al. Precious Net. 17, 1993 Precious Netals. .343-349). In this method, the addition of hydrogen peroxide to a solution of hydrochloric and sulfuric acids will lead to increased consumption of reagents, to the generation and evolution of gaseous chlorine in an amount that reduces the environmental safety and purity of the process. A modification of this method is a method for extracting precious metals from materials containing them, including leaching materials with a solution containing chloride ions, introducing sulfuric acid and hydrogen peroxide into the leaching solution, subsequent processing of the productive solution with the recovery of precious metals and returning the processed solution to leaching, which differs the fact that sulfuric acid and hydrogen peroxide are introduced into the leach solution in the form of a mixture, and mixing is carried out by introducing peroxide into hydrogen sulfide in sulfuric acid at a molar ratio of H ₂ SO ₄ : H ₂ O ₂ > 1 and upon cooling (patent RU 2167211, IPC ⁷ C22B 11/00, C22B 3/06, 05/20/2001). This method requires significant amounts of hydrogen peroxide, which is inconvenient for large-scale production. There is also a method of processing waste containing copper, zinc, silver and gold (patent RU 2109076, C22B 7/00, C22B 11/00, 04/20/1998), which relates to the processing of waste, mainly metallurgical production with the extraction of copper and zinc, silver and gold in the form of high-grade concentrates. The method is based on processing the starting material with water-salt solutions containing an oxidizing agent to intensify the leaching of valuable components, primarily silver and gold, followed by sorption extraction of gold and silver, selective extraction concentration of copper and zinc and their electrodeposition. The starting material is subjected to oxidative leaching by supplying chlorine gas directly to the pulp. The technical result is achieved by the simultaneous extraction of these metals into the solution at the leaching stage, for which alkaline ammonia-salt solutions containing an oxidizing agent having complexing properties are used as a metal solvent. As an oxidizing agent, active chlorine dosed into the leach pulp is used to maintain a given potential. Subsequent extraction concentration and separation of non-ferrous metals allows you to extract all the valuable components of the solution into commodity forms. The sequence of operations according to the method: the metals are leached at the same time with the indicated solution, sorption of gold and silver onto activated carbon is carried out from the obtained product solution, and this concentration of gold and silver is preceded by subsequent extraction sequential separate extraction of copper and zinc from the productive solution by organic extractants, from which these metals extracted with sulfuric solutions, which are then processed for the final separation of metals. The raffinate obtained after copper extraction, before zinc is extracted from it, is additionally purified from copper, silver and gold by cementation, and gold and silver adsorbed on activated carbon are extracted by cyanidation.

Disadvantages:

1. Difficulties for use in heap leaching due to uncontrolled release of gaseous chlorine into the atmosphere, and also because of the inability to ensure uniform supply of chlorine through the stack material.

2. The complexity, multi-stage scheme and the difficulty of its implementation for industrial metal-containing waste, mainly of metallurgical origin. Iron, contained in a significant amount in metallurgical waste, is not recovered by this method.

3. The use of cyanidation on a large scale, which is dangerous for implementation near industrial centers, where dumps of metallurgical plants are usually located.

There is also a method of extracting precious metals from waste of sulfuric acid production - pyrite cinders obtained by firing iron pyrites - pyrite (Patent RU 2034062, IPC ⁶ C22B 11/00, C22B 11/08, 1995.04.30). Essence - the cinder is subjected to acid treatment, after which the liquid phase is separated, copper and zinc are extracted, the solid phase is crushed in the presence of lime, aeration is carried out at elevated temperatures and pressure, and then cyanide in the presence of a sorbent. The thickened cinder pulp is calcified, classified, the sands are crushed to a grade of 0.01 mm of 95-98%, the classifier drain condensed to a liquid to solid ratio of 1.5-2.5 is oxidized in an autoclave at 80-150 ° C, 1-3 atm; Further, the calcified pulp after cooling is directed either to ordinary cyanide at a temperature of 30-40 ° C, or cyanide at a temperature of 60-80 ° C and pressure. This is followed by sorption leaching with the withdrawal of resins saturated with gold and silver, which after regeneration return to the sorption cycle, and the solutions are sent for refining. The thickened waste pulp is supplied to the destruction of cyanides either in an autoclave (100-160 ° C, 1-3 atm), or by other known methods. This method allows to increase the recovery of precious metals by 20-30%, but is not applicable for the complex processing of large-tonnage waste from metallurgical production. To extract gold from refractory ores and mining waste, a method is known (US Patent No. 4,552,589, C22B 11/08, 1985). According to this method, the starting material is ground, mixed with an additional agent and heated under a pressure of at least 0.7 atm to a temperature of at least 150 ° C. The mixture is then treated with an acid solution, cooled and gold is isolated by cyanidation. The disadvantage is the significant loss of bound gold due to its low recovery. A variant of the method is the separation of gold (Patent RU 2094502, IPC ⁶ C22B 11/00, 1997.10.27) by treating ores, concentrates and mining waste containing a significant amount of bound gold and gold, preserved in various minerals ("hidden gold"). According to the method, the starting material is ground, mixed with alkalis in the ratio of the starting material at least 1: 1 and heated to a temperature of at least 150 ° C, after which the mixture is leached with water, sedimented, the sludge is filtered, and the filter cake is treated with hydrochloric acid solution, after which gold is recovered using bromoform. Dignity - up to 90% of gold is extracted in this way. Disadvantages: only gold which is in a free state and available for interaction with a leaching agent is subjected to isolation, in addition, a lot of alkali is required to implement the method (the amount of alkali is comparable to the feedstock) and the entire mass of the mixture of raw materials with alkali must be heated to a temperature of at least 150 ° C (for specific applications - up to 200-250 ° C). This method is not applicable, not beneficial for the integrated processing of metallurgical waste.

A known method of extracting precious metals from ores by chloride-hypochlorite solution. The recommended solution contains 3% sodium chloride and 0.3% sodium hypochlorite. Extraction of metals from the solution is carried out by electrodeposition on the cathode or in other ways. The solution after adding hypochlorite is again used for leaching (Pat. US 5169503, C22B 3/00, C22B 11/00, 08/08/1992). The recovery of the leachate is carried out either by electrolysis, or by the addition of hypochlorite. Cyanuric acid may be added to slow the decomposition of the leach. For the processing of carbonate ores, a method is known for leaching gold and silver in an alkaline medium at pH 8-13 with a concentrated solution of sodium chloride 5.0-20.0% and a salt of hypochlorite 0.25-2.0%. After the cementation of gold and silver by zinc, hypochlorite is regenerated by electrolysis and the solution is returned to leaching (US 4342592, С22В 3/00, С22В 3/10, 08/03/1982). These methods do not allow the effective extraction of precious metals during underground leaching of ores, since due to the high viscosity of concentrated solutions and brines, the permeability of the ore body decreases, and the use of alkaline solutions will lead to colmatization of the pore space during clay swelling. There is also a method of extracting gold from ores, including preliminary acidification of the ore with an acid solution and leaching of gold with chlorine solutions (RU 2093672, IPC ⁶ ЕВВ 43/28, 1997.10.20). Disadvantages: the method is intended only for the extraction of gold, and an increase in the concentration of sodium ions entering the solution with hypochlorite, more than 5-7 g / l, leads to ion exchange clogging, which reduces the permeability of the ore and the efficiency of gold extraction. In addition, when more concentrated acids are used to increase productivity and, accordingly, a pH of less than 1, when sodium hypochlorite is introduced, it decomposes rapidly with intense gas formation, which reduces the oxidizing agent content in the solution, causes the occurrence of gas clogging, and prevents the leaching process . A known method of selective leaching of metals (EP 1281779, IPC ⁷ C22B 011/00, 02/03/2003), in which the mineral raw materials are contacted in an aqueous solution with oxidizing agents sequentially in the following order: in the presence of oxygen, then oxygen and ozone and then oxygen, ozone and a third reagent. After applying each step, solid and liquid phases are separated. The disadvantages of the method: processing of raw materials is carried out in an aqueous solution, which requires large capacities of reactors, pipelines in anti-corrosion performance, powerful sources of oxygen and ozone, the leaching technology is complex, includes three separation operations, insufficient selectivity of metal extraction. Known close to this invention is a method of processing refractory mineral raw materials containing metals (RU 2265068, IPC ⁷ C22B 3/06, 2005.11.27), includes leaching refractory mineral raw materials in an aqueous acid solution with a concentration of 1.8-50 g / dm ³ active oxygen in the presence of ferric ions and the extraction of metals from the resulting leachate. Moreover, after leaching of refractory mineral raw materials, the obtained product is separated into liquid and solid phases and metals are extracted from the liquid and / or solid phase. For leaching, oxidizing or active oxygen-forming oxidants are used: ozone, or hydrogen peroxide, or singlet oxygen, or atomic oxygen, or oxygen-containing radicals, or a mixture of at least two of these oxidizing agents, and superoxide, hydroperoxide, can be used as an oxygen-containing radical hydroxyl and others. Also, when leaching refractory mineral raw materials, an inorganic acid solution, preferably sulfuric or hydrochloric, is used. In this case, the leaching of refractory mineral raw materials using an oxidizing agent containing or forming reactive oxygen species is carried out at atmospheric pressure or greater at 40-95 ° C. The recovery of leached metals can be carried out without separation of the leachate into phases, for example, by the sorption method, or from the solid and liquid phases of the leachate after separation. According to this method, the leaching of refractory mineral raw materials is carried out in tanks with a solution, with ultraviolet irradiation, with a hydroacoustic effect on the solution, providing a cavitation mode, and in the hydrodynamic mode, when the solution flows containing gas and a solid phase are twisted, with possible vibrational mixing in the solution , resonant waves, or vibrations, or shock waves. Leaching of mineral raw materials is carried out with its preliminary ultrasonic treatment and / or in the process of leaching, for which it is proposed to use inorganic acid, preferably sulfuric or hydrochloric. The disadvantages of this method: significant energy consumption, expensive equipment is required in anticorrosive performance: abrasion-resistant pipelines, separators, large-capacity reactors operating at elevated temperatures and pressure, equipped with powerful generators of ultrasound, cavitation, shock waves, ultraviolet radiation, powerful sources of oxygen and ozone which are difficult to create, which determines the complexity of the invention. Such leach solutions are highly corrosive and should be used in expensive equipment that is inert to these substances. In addition, ultrasonic and other treatments lead to additional wear of the equipment, which significantly reduces the economic effect when implementing this method. This method is difficult for the integrated processing of large-scale waste of the metallurgical industry. A known method of hydrometallurgical extraction of rare metals from technologically refractory raw materials (Patent RU 2114196, IPC ⁶ C22B 3/04, 06/27/1998), in which refractory raw materials are crushed, placed in a sealed vessel containing complexing agents for rare metals, a solution of halogen acids, nitrous acid . Oxygen is supplied to the vessel. The process is conducted at a certain pH of the reaction mixture, pressure and half-wave potential of oxidizing agents for a sufficient time, which is chosen from the condition of opening the matrix of raw materials for maximum oxidation and extraction of rare metals from the matrix and the formation of a mother liquor, including dissolved complexes and oxides of rare metals. The extraction of rare metals from the mother liquor is carried out by known methods. This method is periodic, requires a special vessel operating under pressure, control of many process parameters and is not applicable for the processing of large-capacity raw materials depleted in metals. The invention relates to the field of processing oxidized technologically resistant raw materials, in particular, to the processing of ash and slag waste from burning coal in order to extract rare earth and radioactive metals. Such control requires complex and expensive equipment, which significantly reduces the economic effect of this method, especially for processing such raw materials poor in rare metals as ash and slag waste from the combustion of thermal coal. The chloride-hypochlorite system, as follows from the analysis of analogues, can be used as an alternative to cyanide. But here a technical contradiction arises. In methods that use a cyanide-free leach solution containing a hypochlorite-based oxidizing agent and acid, it is likely that the leach solution decomposes due to the decomposition of hypochlorite with the release of chlorine even at the stage of preparation of the leach solution. These methods, as shown above, are not suitable for heap leaching due to the uncontrolled release of gaseous chlorine into the atmosphere, and also because of the impossibility of ensuring a uniform supply of chlorine through the stack material, since the movement of gas through the finely dispersed material proceeds predominantly through the channels. In addition, the process is conducted in the acidic region, where the solubility of chlorine is low (<0.5%), its volatility is high, and that is why even for vat leaching, the oxidizing potential of chlorine and the corresponding oxidizing agents is not fully used. This necessitates additional measures to control the process, solution, its stabilization, requires constant monitoring of such solutions, limits the range of working concentrations of the components and the use of such solutions. A known hydrometallurgical method for the extraction of metals from refractory sulfide ore (RU 2086682, IPC ⁶ C22B 11/00, C22B 11/08, 1997.08.10). The method includes crushing the ore to a nominal size of at least 0.64 cm, acidifying it with mineral acid, treating the acidified ore with nitric acid. The treated ore is placed on top of an impermeable collector in the form of a heap permeable layer through which an aqueous solution of nitric acid is dispersed, and then water washing of the heap ore is carried out. After washing the ore, it is leached and precious metals are recovered from the leach solution. The NOx gases generated during the pre-oxidation of the ore are supplied to the nitric acid generator to convert them to nitric acid, which is recycled to treat the ore.

Stage:

a) crushing ore to a nominal size of not less than 0.64 cm;

b) treating the crushed ore with a mineral acid (preferably sulfuric acid) with a pH of the resulting mixture of about 2 or lower (preferably up to a pH of about 1);

c) treatment of acidified ore with nitric acid: from 5 to 200% of the stoichiometrically necessary for interaction with the ore and extraction of NOx gas released from the ore;

d) optionally adding an acid-resistant binder to the nitric acid-treated ore to form ore agglomerates capable of retaining the porous ore layer while maintaining the binder and ore in contact with each other for an exposure time sufficient to allow the ore agglomerates to retain their specific shape and recover NOx released at this stage (d);

e) placing the ore thus treated in the form of a heap permeable layer of ore on top of an impermeable collector;

f) heap processing of the permeable ore layer by continuous or intermittent dispersion of an aqueous solution of nitric acid through the layer;

g) separating the residual acid liquid from the heap permeable ore layer;

h) water washing the heap permeable ore layer to remove the nitric acid solution and separating the leaching from the ore layer;

i) introducing NOx gases recovered in steps (c) and (d) into a nitric acid generator to convert NOx to nitric acid and recycling said nitric acid for use in processing said ore;

j) optionally treating the heap permeable ore layer with a sufficient amount of calcium, sodium or magnesium ions in an alkaline medium (preferably calcium carbonate, calcium hydroxide, sodium hydroxide or magnesium hydroxide) to increase the pH of the liquid removed from the layer to 10 or higher;

k) treating the heap permeable ore layer by continuously or intermittently dispersing a noble metal leach reagent through the layer;

l) separating the leach solution containing the dissolved noble metals from the heap permeable ore layer and recovering said noble metals from the leach solution.

This method is the closest analogue to the proposed technical solution. This method is aimed at eliminating the harmful effects of nitrogen oxides vapors released during the treatment of ore with nitric acid of a cyanide-containing solution during irrigation, but has its negative aspects: starting acidification of the ore with a large amount of mineral acid is required, and for carbonate ores there is a risk of their formation with gypsum, about than the patent says. Only a large amount of concentrated sulfuric acid is required for this initial treatment. Then the ore in rotary mixers is treated with nitric acid and a heap (stack) is poured. This requires powerful corrosion-resistant equipment, appropriate conveyors, etc., and it takes a certain time to contact the ore and nitric acid, as noted in the patent. It is necessary to capture nitrogen oxides (for environmental and economic reasons), and the ore is agglomerated to preserve the porous layer with the introduction of acid-resistant. Capturing nitrogen oxides is difficult, expensive, and requires an extensive network of mixers, pipes, traps (all in an anti-corrosion version). This method contains many acid pretreatment operations, including hazardous transport operations for transporting minerals impregnated with concentrated mineral acids. The method comprises washing operations from acids with pH neutralization (with transfer to the alkaline region to pH = 10) contained in the pores of ore pieces of mineral acids for mandatory preparation for gold cyanide leaching. A significant drawback of this method is the low efficiency and duration of the metal extraction process when passing reagent solutions through a rock mass (up to 61 m high as described) under the influence of gravitational forces. It depends on the filtration properties of the stack, the density of the irrigation system. In particular, with almost any organization of the technology for feeding solutions to the stack, there is a heterogeneity in the leaching of the layers along the height of the heap: in the upper layers, the solid material can completely come into contact with the reagent solutions, and then the solutions move along the most accessible pore space guides with the formation of cracks, fistulas and rock outfall, which dramatically reduces the contact surface of the ore and the reagent and, accordingly, the effectiveness of the method applicable only for processing by cyanidation of sulfide s ore-containing ores, which can recoup all costs.

The prototype is designed to extract precious metals, so all the numerous operations on it are preliminary for opening the ore with the extraction of precious metals by cyanidation, for which the ore is washed from acid, alkaline neutralization of the processed ore.

In addition to crushing, the prototype includes operations:

- pre-treatment of pieces of raw materials with mineral acid in rotary devices;

- additional treatment with nitric acid (in rotary apparatuses) to ensure agglomeration of pieces of ore to prevent colmatization of the ore ore fines;

- dumping of processed ore in the form of a stack (“heap permeable layer”);

- irrigation of the resulting stack with nitric acid;

- capture vapors of nitrogen oxides that appeared during the processing of ore with nitric acid, with their recycling for recycling of nitric acid for processing stacks;

- separation of the residual nitric acid solution from the ore;

- washing the stack with water to remove acid from the ore;

- separation of leaching from ore;

- additional processing of the stack with an alkaline solution containing carbonates and / or hydroxides of alkali and / or alkaline earth metals to change the pH of the liquid impregnating the stack to pH = 10 or more;

- direct leaching of ore by passing through a stack of leaching reagent (cyanide leaching);

- separation from the stack of a productive solution containing dissolved noble metals, the extraction of these metals.

All multi-stage processing of the prototype is aimed at preparing the ore for leaching. Mechanochemical processing of the ore in several stages with nitric acid is preferred. In this method, the ore stack can also be subjected to processing steps without moving or destroying the heap layer: first it is treated with heap oxidation by adding nitric acid and the final oxidation of the remaining sulfide compounds, then it is washed with water, sequentially treated with lime at the stage of neutralization and finally treated with heap leaching with sodium cyanide, and all these stages can be carried out in any way without destroying the layer. But this variant of the prototype method is simplified and does not provide the surface of all ore pieces wetted by nitric acid, in contrast to the mechanochemical treatment of ore pieces with nitric acid in the prototype in special rotary devices with the capture of nitrogen oxide vapors released during this process and their subsequent regeneration into nitrogen acid in special apparatuses and directing the obtained nitric acid to ore processing, as described in the prototype.

Thus, a method is needed to increase the efficiency of metal extraction, preferably in case of heap leaching of metals from ores, large-tonnage industrial metal-containing wastes, for example, metallurgical production, including those containing gold, which would increase the speed and completeness of processing without the use of toxic reagents, with a decrease in emissions harmful gases into the atmosphere and with the simplification of the process.

From the analysis of the existing technical level, it is obvious that there are a number of contradictions characteristic of the known methods for the extraction of metals from ores and industrial wastes. Extraction of noble, non-ferrous metals and iron in a single technological cycle is extremely difficult, and profitability is ensured only by the extraction of gold, which requires high dispersion of the grinding of raw materials and / or the use of toxic and environmentally hazardous leaching solutions, in particular, cyanide, in large volumes. Non-cyanic leach solutions based on acids and hypochlorite are not selective and, along with the dissolution of gold, transfer a large amount of iron into the solution. Loss of gold occurs during its sorption on iron compounds, for example, on hydroxides. In addition, hypochlorite acid leach solutions for gold recovery are not stable, tend to decompose rapidly with the release of chlorine, which is environmentally hazardous and leads to additional costs. Sodium hypochlorite is stable at room temperature in alkaline solutions and unstable in solutions of mineral acids. Therefore, it is impossible to prepare a pre-leaching solution of sodium hypochlorite in sulfuric acid, as is proposed in the known methods, due to the rapid evolution of gaseous chlorine and chlorine oxide. Autoclave methods are difficult to implement, they require equipment with high pressure and / or high temperature, with stirring, with cavitation, etc., are difficult to control in continuous processes. Grinding ore to a high dispersion, necessary for opening resistant ores, requires various grinding operations with high energy consumption and the use of special equipment, which reduces the profitability of processing.

The technical result achieved by the invention is to increase the efficiency of the integrated processing of metal-containing mineral raw materials, in particular industrial metal-containing waste (PMO), including waste from metallurgical industries, by ensuring the selectivity of extracting iron, noble and non-ferrous metals in a single technological cycle without high dispersion of grinding of raw materials while reducing costs and emissions of harmful gases. The technical result is achieved by the fact that a stack is formed from crushed raw materials, which are pre-treated by feeding them separately or in the form of a mixture of solutions of a surfactant and hypochlorite. Then the stack is treated with a leach solution, which is obtained by mixing in the volume of the stack when fed separately or as a mixture of solutions containing hypochlorite, surfactant and mineral acid. Mixtures of mineral acids or sequentially introduced mineral acids are used in the leach solution. The places of supply to the stack of these solutions may not coincide. Metals are recovered from the productive solution obtained in the stack. As a result, an increase in the degree of metal recovery, reduction in leaching time, and reduction of costs and environmentally harmful emissions are achieved.

The method is as follows. According to the proposed method, raw materials (metallurgical waste, etc.) are crushed, for example, to a particle size of -10 + 0 mm and then the stack is dumped. After crushing, a fine fraction can be separated, for example, class -2 + 0 mm, which is then separately processed, for example, by agitation leaching. For preliminary processing of raw materials, surfactant and hypochlorite solutions are introduced into the stack, for example, first a surfactant solution is fed into the stack, and then a hypochlorite solution, or a mixture of surfactant and hypochlorite solutions is fed into the stack, controlling their mass content for a particular processed raw material. The surfactant solution may contain one or more surfactants, for example, sulfanol, polyacrylamide. The leach solution is obtained by mixing in the volume of the stack when fed separately and alternately aqueous solutions containing hypochlorite, surfactant and / or mineral acid. Mixtures of mineral acids or sequentially introduced mineral acids can be used in the leach solution. Places of supply of solutions to the stack may not coincide. Metals are recovered from the productive solution obtained in the stack. During pretreatment of a stack of surfactants and hypochlorite, interconnected and mutually reinforcing effects occur: adsorption lowering of surface energy (Rebinder effect) and activation of the surface of pieces of raw materials, the appearance of multiple activation centers, including at the interphase boundaries of inclusions, removal of surface films, increase in effective the surface of the particles (pieces) of raw materials. As a result, the surface of the pieces of processed raw materials is effectively wetted and a transition is made from the jet stream of the solution to thin-film. The development of existing cracks and the emergence of new microcracks in pieces of raw materials. Surfactants and active chlorine from the solution are sorbed on free surfaces, primarily on the surface of cracks, including newly formed ones, thereby enhancing the “wedging effect”. Therefore, pre-treatment enhances cracking in the particles of raw materials, ensuring the penetration of a solution containing hypochlorite into existing and new microcracks, pores of the particles of raw materials, thereby preparing them for leaching. During hydrolysis of hypochlorite, chlorine, oxygen are released and hypochlorous HOC1 and hydrochloric acid HCl are formed, thereby creating an already defined acidic environment. An additional process is the generation of hydrogen chloride through a chain reaction.

H ₂ + Cl ^- = HCl + H ⁺ , H ⁺ + Cl ₂ = HCl + Cl ⁺ , H ₂ + Cl ^- = HCl + H ⁺ , etc.

In this case, the generated hydrogen chloride forms dilute hydrochloric acid in the film of the solution, accelerating the destruction of carbonates and sulfates in the feed with the formation of soluble chlorides, which allows the destruction of carbonates and sulfates in the feed and further expands micropores and prevents their clogging with calcium sulfate. The pores are cleaned and decolmatized with leaching of small particles filling them, which facilitates leaching. Hydrochloric acid destroys sulfides of metals, for example, iron and zinc, which are present in the waste products of electrometallurgical production, converting them into solution: 2HCl + FeS = FeCl2 + H ₂ S

But hydrogen sulfide is readily soluble in a solution having a large effective surface on particles in a stack, and is oxidized to sulfur by solution oxygen:

2H ₂ S + O ₂ = 2S + 2H ₂ O.

With the development in the raw material particles of a network of microcracks filled first with surfactant and hypochlorite, and then with a leaching solution, they additionally occur: their gradual opening, decrease in the strength of the particles, their further destruction due to the weight of the overlying layers of the raw material. This improves the further leaching of metals. After pre-processing the stack, a leach solution containing hypochlorite, surfactant and / or acid flows into the microcracks and pores of the raw material particles, the surface of which is already coated with a thin layer of surfactant and is already activated. In this case, chlorine, which is released as a result of the decomposition of hypochlorite, is actively absorbed by the developed surface film of a solution covering particles of raw materials in the mass of the stack. This is due to the fact that the effective surface of the particles of raw materials in the stack is several orders of magnitude higher than the geometric surface of the stack. Thus, a dynamic equilibrium arises and is maintained in the stack volume: “gas exit from the solution and its absorption by the solution with recycling of hypochlorite in the solution”. Moreover, the probability of gas escape from the stack is small. As a result, they decrease: hypochlorite consumption, loss of chlorine, its emission into the atmosphere. The introduction of a solution of hypochlorite directly into the volume of the stack, for example, to a depth of 0.1-0.25 m below the surface of the stack, is carried out by using a specially perforated pipeline. As a result, the release of gases into the air above the surface of the stack is minimized. The released gas is re-dissolved in the film of the solution flowing around the surface of the particles of raw materials in the stack, and carried away deep into. Due to this, leaching is intensified, the likelihood of gas clogging of the pore space of the raw material particles with microbubbles of gas is reduced. In addition, carbonate structures undergo decomposition and go into solution in the form of salts. The process proceeds with the surface wetting of the particles of raw materials, which is characteristic of both the internal volume of the stack mass being subjected to leaching and the surface of the stack. This is facilitated by both the developed fractal surface of the particles themselves and the significant resulting surface of the stack itself, both external and especially internal (inside the stack), which is many orders of magnitude superior to the surface of the array, calculated from ordinary geometric considerations. Leaching processes take place in a rather thin film (0.05–2 mm) of the solution, which actually simply wetts the developed surface of the particles, eliminating the appearance of “non-wetting” of the particles. As a result, for the leaching solution, the ratio “surface area / volume” is several orders of magnitude (at least 3-4 orders of magnitude) higher than the value of the same ratio for volumetric reactors. This leads to a sharp increase in the role of diffusion and surface processes of evolution and absorption of gaseous products of the reactions undergoing, contributes to the accelerated development of a network of microcracks, their further expansion, and the opening of the resistant structure of the raw material particles. In addition, the weight of the overlying layers of raw materials in the stack leads to the growth of cracks in pieces of raw materials that develop both in the pretreatment process and directly in the leaching process. Thus, these effects together and additionally contribute to the opening of raw materials and the extraction of metals, which according to this method from the resulting productive solution is carried out by known methods, for example, electrolytic or hydroxide deposition, cementation on iron scrap or iron powder, deposition of gold on zinc powder or sorption of gold by activated carbon . These metal recovery processes can proceed sequentially using a leach solution containing one mineral acid. If the leach solution contains several successively exchanged mineral acids, then metals are extracted by known methods from each acid. In the processing of raw materials containing gold, after pre-treatment, a leaching solution containing no oxidizing agent is supplied. Thus, metals are leached into the productive solution, from which they are then extracted. To optimize the recovery of metals, the leach solution may contain several mineral acids introduced and successively replaced by one another. Thus, after preliminary treatment with a leaching solution, non-ferrous metals (zinc, copper, etc.) and iron are extracted, the concentrations of which are 3-5 orders of magnitude higher than the concentration of gold. As a result, a number of positive effects are additionally obtained: the concentration of gold in the processed raw materials increases, a system of cracks and pores in the exposed particles of the raw material develops, which together greatly facilitates the extraction of gold. In addition, the preliminary extraction of a significant amount of iron dramatically reduces the unproductive losses of gold during its sorption on iron compounds, characteristic of known methods. The method allows to extract metals from PMO and ores, including those containing gold.

Examples of specific performance.

Example 1. The processing of the solid residue formed during the neutralization of waste galvanic production - "galvanic sludge". The feedstock (the starting composition is shown in Table 1) is a dense rock-like material with a hardness of at least 25 MPa. It was crushed to a nominal particle size of 0.5 mm. A 20 kg sample was placed in a vertical column representing the process of heap leaching. The surface of the crushed galvanic sludge was irrigated with a 15% hydrochloric acid solution (without the addition of an oxidizing agent and surfactant) for 20 hours at a flow rate of 10 l / h. After leaching, the obtained cake was washed and its residual composition was determined by X-ray microanalysis using a KarlZeiss scanning electron microscope equipped with an energy dispersive attachment. The result is in table 1.

Example 2. The feedstock, conditions and equipment of example 1. Previously, the surface of the crushed galvanic sludge was irrigated with an aqueous solution containing sulfanol (1 g / l) and sodium hypochlorite (20 g / l) for 10 hours. Then the leaching solution was processed: 15% hydrochloric acid, sodium hypochlorite (20 g / l), sulfanol (1 g / l) for 20 hours. The elemental composition of the initial galvanic sludge and the mineral powder obtained after its processing are shown in table 1.

Table 1. The elemental composition of galvanic sludge and mineral powder obtained from it as a result of metal extraction. Mass% FROM ABOUT Mg Al Si K Fe Cu Zn Sn Ni Pb Source sludge 7.2 10.3 1,5 1,5 11.1 2.9 6.4 21.3 9.5 1,5 21.7 5.1 Processing, example 1. 15.1 19.5 0.8 1.9 17.5 1.3 3,5 5.1 3,7 0.9 7.9 1,5 Processing, example 2. 26.1 46.1 0.4 2,5 22.3 0.2 1.8 0.15 0.17 0.11 0.08 0.09

After galvanic sludge processing, the particles of mineral powder have a developed system of microcracks, which are easier and easier to grind and separate, followed by fractionation. Its composition is close to aluminosilicates, consists of aluminum oxides, silicon - solid materials and can be effectively used in construction, including road, as a durable filler with a high specific surface.

Example 3. The processing of stale clinker - waste electrometallurgical zinc production of JSC "Electrozinc" (Vladikavkaz). The clinker composition is shown in table 2.

Table 2. Clinker composition at the industrial site (according to OJSC “Electrozinc”) Zn% Cu% Pb% Fe% Au g / t Ag g / t SiO _2% CaO% Al ₂ O ₃ MqO% S% FROM % 0.8-1.6 0.7-1 0.3-0.8 25-28 0.6-0.8 40-200 31-33 4-6 1.4-1.6 1-1.3 2-4 1-1-15

After crushing, the magnetic fraction was separated from the initial clinker, which was screened with fractionation by size: -2 + 0 and -10 + 2 mm. Their composition is given in table 3.

Table 3. The composition of the clinker fractions Description The content of the determined element,% Fe Al Zn Cu SiO ₂ Source clinker 23.9 1.88 1.49 0.97 2.91 Magnetic fraction -2 + 0 32,5 1.12 0.55 0.41 3.30 Magnetic fraction -10 + 2 23.1 2.49 0.94 0.54 3.61

Clinker magnetic fraction was leached in Plexiglas columns (working height 475 mm, diameter 52 mm) at 18-22 ° С. Pre-weighed samples of the magnetic fraction of the clinker were poured with a seal into the column and the solutions were fed from above through irrigation nozzles, controlling the flow rate using a measuring cylinder with filling for 1-5 minutes. The ratio of the volume of the supplied leach solution to the mass of the sample in the cycle was maintained at the level of W / T = 4-7. The productive solution was collected in a receiving container, from which, after each cycle, a sample was taken for analysis for the content of free H ₂ SO ₄ and metals. After measuring the volume and adjusting the acid content in the solution by adding the calculated amount of concentrated H ₂ SO ₄ and water to 4%, the productive solution was fed to the next leaching cycle. The contents of the main elements in solutions were determined by atomic absorption spectroscopy (AAS) on a QUANT-2A setup (for Fe, Al, Zn, Cu) and the atomic-emission method with inductively coupled plasma Analyst-400 (Si spectrophotometry). Table 4 shows the extraction of iron in the production solution over a different number of leaching cycles in a column. Option A — leaching of the magnetic fraction of clinker (4% sulfuric acid solution), option B — clinker treatment with a surfactant solution (based on sulfanol) with leaching with a 4% sulfuric acid solution. Kinetics of leaching shows an increase in the rate of extraction of metal from clinker by the proposed method.

Table 4. Extraction of iron in a productive solution for options A and B. Cycle number The degree of extraction of iron,% BUT AT one 5.9 6.5 2 9.0 12.0 3 11.0 19.5 four 11.5 27.0 5 17.0 29.0 6 20,0 33.0 12 30.5 -

The composition of the productive solution after cycle 7 are shown in table 5.

Table 5. The composition of the productive solution (cycle 7) cycle H ₂ SO ₄ free, g / l The content of the determined element, g / l Fe Al Zn Cu SiO ₂ 7 23.0 46.2 5,0 3,5 1.16 32,5

In the productive solution, formation of silicic acid gel is noted, which can be isolated together with iron by known methods as an intermediate.

Example 4

Clinker was treated with various model solutions in order to verify their effect and the absence of loss of precious metals with different clinker processing options. Leach solution I was prepared by dissolving 10% H ₂ SO ₄ in distilled water to a content of 4.0% H ₂ SO ₄ according to potentiometric titration. Solution II was prepared by adding 10% H ₂ SO ₄ while stirring to a solution of sodium hypochlorite with an initial content of 74 g / l of active chlorine until the first chlorine bubbles appeared. Then this solution is diluted with water to a content of 11 g / l of active chlorine. According to the potentiometric determination, 3.72 mol / L NaOH was contained in the initial solution. An additional 3.0 mg / L of gold in the form of hydrochloric acid was added to the solutions, and the gold content in the solution was monitored by the AAS method. After a certain time, the resulting solution was decanted and filtered through a paper filter. The content of Au, Ag, Fe, Cu, Zn, Al, Si in the filtrates was determined by atomic absorption spectroscopy (AAS). The measurement error does not exceed ± 5%. The initial gold content in the model solutions was 3 mg / L; silver entered the solution from the initial clinker during leaching. All available gold in the initial solution I for a short time (1 hour) interacts with clinker, as a mineral sorbent, and completely precipitates from the solution into the solid phase. In the process of leaching clinker with solution II containing 11 g / l of active chlorine, gold with an initial concentration of 3 mg / dm practically does not precipitate on the solid phase within 120 hours of contact. The silver content during leaching with solution I remains constant within the measurement error of about 1 mg / DM ³ . In solution II, the concentration of Ag increased from 5.2 mg / dm in 1 hour to 13.0 mg / dm ³ in 120 hours.

Thus, it can be concluded that solution II with sodium hypochlorite with a content of 11 g / l of active chlorine ensures the stability of the extraction processes of Au and Ag, while sulfate systems are not suitable for the recovery of precious metals and cannot block their losses during the leaching process.

Example 5. The clinker was processed (according to example 3) for 120 hours with solutions according to various options in order to determine the extraction of metals. Options: A1 - with the introduction of a solution of 4% H ₂ SO ₄ into the treated clinker, A2 - leaching of the clinker only with sodium hypochlorite solution containing 11 g / l of active chlorine. Table 6 shows the results of the analysis of the composition of the initial clinker and solid residues after its processing according to various options, and in table 7 the degree of extraction of elements.

Table 6. The content of elements in the original clinker sample and solid residues after clinker treatment. Solid products The content of macrocomponents,% Fe Cu Zn Al Si Source clinker 28 2.6 3.4 1,6 31 Solid product after A1 treatment 9 0.3 0.2 2,5 fifty Solid product after A2 treatment 28 0.4 0.2 2.6 33

Table 7. Extraction of elements in clinker processing processes for 120 hours. Processing options Recovery to solution Fe Cu Zn Al Si A1 80 92 97 5 four A2 5 9 5 6 0.4

Example 6. Clinker (A3) was treated (composition as in Example 3) for 120 hours sequentially with solutions of mineral acids: sulfuric (4%), nitric (2%) and a hypochlorite solution containing 11 g / l of active chlorine containing hypochlorous acid (HClO), as a product of hydrolysis of hypochlorite. Table 8 shows the degree of extraction of elements.

Table 8. Extraction of elements in clinker processing processes for 120 hours. Processing option Recovery in solution,% Au Ag Fe Cu Zn Al Si A3 71.5 69.7 87 94.5 98.7 7 7.7

It is seen that in this method the degree of extraction of metals from clinker increases.

Example 7. The clinker was processed (according to example 3) according to the proposed method. Table 9 shows the gas concentration measurements at different distances from the gas emission source. Measurements of gas concentrations were carried out with the Ule-2 instrument.

Table 9. Emission of harmful gases into the atmosphere during heap leaching of clinker Sampling Place Concentration, mg / m3 (% vol) H ₂ s CO ₂ SO ₂ L = 1 m from the source (The experiments were carried out on a column ⌀ = 190 mm, h = 1.35 m) 0 0.5 12 - "- 0 0.13 10 - "- 0 0.13 17 - "- 0 0.12 eleven - "- 0 0.2 four - "- 0 0.17 eleven L = 2 m from the source 0 0.5 12 - "- 0 0.05 17 - "- 0 0 eleven - "- 0 0.1 four - "- 0 0.09 eleven

It can be seen that the concentrations of H ₂ S and SO _{2 are} overestimated only at a distance of 1 m. Moreover, with heap leaching, they did not change in time, and therefore do not depend on the initial concentration of the reagent and heavy metals in the productive solution. This is well explained by the above considerations from the point of view of the existence of dynamic equilibrium in different physicochemical processes of generation, sorption and desorption, the interaction of gases with each other and with clinker components, which leads to a fairly effective mutual neutralization of them. At the same time, H ₂ S is absent in the solution collector, and the concentration of other gases, as a rule, is much lower than in the column. The emission of carbon dioxide is explained by the reactions of acids with carbonates, both with their residues in the clinker, and with carbonates, which gradually formed during the long-term storage of the clinker in the open. Therefore, the emission of carbon dioxide is small. The yield of SO _{2 is} practically independent of the time and type of the process and is mainly determined by desorption from the branched structure of clinker particles coated with a film of a leach solution, with SO ₂ being in chemical equilibrium in the solution. When dissolved in water, sulfur dioxide forms sulfuric acid. In this case, sulfur from 4-valence becomes 6-valence, and sulfurous acid is easily oxidized to sulfuric acid by the oxygen present in the solution:

2H ₂ SO ₃ + O ₂ = 2H ₂ SO ₄

The resulting H ₂ SO ₄ is subsequently involved in the leaching of clinker. In addition, in addition, during the acid treatment of metallic iron contained in the clinker, hydrogen ions, which are a strong reducing agent, are released. They participate in redox reactions, but most of the hydrogen ions form molecular hydrogen, which is rapidly desorbed from the solution, and then, due to its lightness, disappears from the clinker massif. Due to its lightness, it does not accumulate, but flies into the upper atmosphere, so that the formation of explosive concentrations at KB is excluded. Thus, the processing of clinker according to the claimed method does not produce significant emissions of harmful gases. Experimental data indicate a fairly complete mutual neutralization of gaseous leaching products.

Claims (5)

1. The method of extracting metals from ores and industrial waste, including crushing the raw material, dumping it in the form of a stack, pre-processing the raw materials in the stack with an aqueous solution, subsequent processing of the raw materials in the stack with a leaching solution, dissolving the metals and obtaining a productive solution with the extraction of metals, different the fact that the preliminary processing of raw materials in the stack is carried out by feeding separately or in the form of a mixture of solutions containing a surfactant and hypochlorite into the stack, and subsequent processing raw materials in the stack leach solution is carried out feeding a mineral acid solution, or mixtures of mineral acids, or a solution obtained by mixing in the bulk of the stack by being supplied separately or as a mixture of solutions containing a mineral acid, hypochlorite and a surfactant. 2. The method according to claim 1, characterized in that the preliminary treatment is carried out by sequentially feeding solutions of a surfactant and hypochlorite into a stack. 3. The method according to claim 1, characterized in that the preliminary treatment is carried out with a mixture of surfactant and hypochlorite solutions. 4. The method according to claim 1, characterized in that when leaching use a solution of a mixture of mineral acids or sequentially introduced solutions of mineral acids. 5. The method according to claim 1, characterized in that the solutions are fed into the volume of the stack in mismatched places.