RU2550764C1 - Method of metal extraction from ores - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: metal extraction method comprises a sequential formation injection through the system of injection wells with the solution containing hydrogen chloride and sodium hypochlorite, pumping-out of productive solutions through the system of extraction wells. After supply of the injection solution into the formation the hydraulic medium. providing pH acidity of the solution at the level 1.5-2.5, is injected at the pressure exceeding the formation pressure, the hydraulic impact in the formation is generated which is an additional leaching agent. The hydraulic medium is sulphuric, nitric, coal or sulphurous acid or their mixes. The hydraulic medium can be the mixing solutions of sodium carbonate-hydrocarbonate (Na₂CO₃+NaHCO₃), ammonium carbonate-hydrocarbonate ((NH₄)₂CO₃+NH₄HCO₃), sodium carbonate-hydroxide (Na₂CO₃+NaOH) or the brine with sodium carbonate saturated with CO₂. After supply of the hydraulic medium into the formation the injection solution containing sand with the fraction 0.5-2 mm is supplied again.

EFFECT: improvement of efficiency of metal extraction, decrease of negative environment impact.

7 cl, 1 dwg

Description

The invention relates to the mining industry, in particular to the technology of leaching of metal, and can be used for underground leaching of metals from ores.

A known method of extracting metal from ores, including preliminary acidification of the ore with a solution of hydrochloric acid and leaching of ore with hydrochloric acid solutions containing halite and molecular chlorine. There is also known a method of extracting metal from ores, including the preparation of a leaching solution of hydrochloric or other mineral acid, neutralized with an alkaline solution of sodium or potassium hypochlorite. The neutralization is carried out immediately before the acid solution is fed into the ore [RF Patent No. 2094605, publ. 10/27/1997]. The disadvantage of this method is the insufficiently high metal recovery, since in the alkaline environment it is precipitated and partially sorbed onto clay minerals.

A method for extracting uranium from ores by heap or underground leaching is proposed, which includes the preparation of leaching solutions containing sulfuric acid, filtering them through ore with the conversion of uranium, iron and other metals into filtrates and extracting uranium from them to obtain mother liquors. Leaching solutions are prepared by treating the aqueous phase with sulfur dioxide and an oxygen-containing gas to form sulfuric and sulfuric acids, while the total concentration of sulfuric and sulfuric acids in the range of 3-30 g / l, mainly 5-20 g / l, is maintained in the leaching solutions, and the ratio the concentration of ferric and ferrous ions is maintained equal to or more than 0.5 [RF Patent No. 2234550, publ. 08/20/2004]. The disadvantage of this method is the insufficiently high metal recovery due to gypsum filtration channel.

To improve the leaching technology, a method is proposed that involves leaching uranium and iron with a solution of sulfuric acid using ferric iron contained in the ore as an oxidizing agent, then uranium is extracted from the solution to obtain a solution containing ferrous iron, and the ferrous iron is regenerated to ferric oxidation to obtain circulating solution and its recirculation to leach ore. In this case, the extraction of uranium from the solution is carried out by sorption on anion exchange resin, the solution containing ferrous iron obtained after sorption is acidified with ferrous acid to ferric iron before regeneration in it, and regeneration is carried out by irradiation with an accelerated electron flux at an absorbed dose rate of 2.3-3.5 kGy / s for 1-6 minutes [RF Patent No. 2326177, publ. 06/10/2008]. Disadvantage: high costs of regeneration by electron irradiation.

There is also known a method of extracting gold from ores, including preliminary acidification of the ore with an acid solution and leaching of gold with chlorine solutions [RF Patent No. 2093672, publ. 10.20.1997]. 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.

There is also known a method of extracting metals from metal-containing mineral raw materials [RF Patent No. 2476610, publ. 02.27.2013], according to which, in a method for extracting metals from ores and industrial wastes, including crushing the raw materials, dumping them in the form of a stack, preliminary processing of 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 extraction of metals from it, preliminary processing of raw materials in a 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 the subsequent processing the leaching of raw materials in the stack with a leaching solution is carried out by supplying a solution of mineral acid, or a mixture of mineral acids, or a solution obtained by mixing in the volume of the stack when fed separately or as a mixture of solutions containing mineral acid, hypochlorite and a surfactant.

The disadvantage of this method should be considered the need for large volumes of mining operations with the cost of mechanical energy and poor working conditions.

Closest to the proposed method is a method for extracting gold from ores at the place of their occurrence, including sequential injection into the reservoir through a system of injection wells of a solution containing hypochlorite and sodium chloride, pumping productive solutions through a system of pumping wells, in which the injection solution additionally contains hydrogen chloride at the following ratio of components, g / l: Sodium hypochlorite 0.4-1.0; Sodium Chloride 3.0-4.0; Hydrogen chloride 0.3-1.0. [RF Patent No. 2246002, publ. 02/10/2005. Bull. No. 4 is a prototype]. 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.

At the same time, leaching of heavy metals such as uranium with this method will not give the desired metal recoverability.

The objective of the invention is to create a method for extracting metal from ores in which the functionality of the method is expanded, productivity is improved, economic indicators of the method are improved, and harmful effects on the environment are reduced. This problem is solved by the fact that a method for extracting metals from ores is proposed, which includes sequential injection into a formation through a system of injection wells of a solution containing hydrogen chloride and sodium hypochlorite, pumping productive solutions through a system of pumping wells, and, after the injection solution is fed into the formation, pressure exceeding the pressure in the reservoir, a hydraulic medium that provides a solution acidity of pH 1.5-2.5, the formation of water hammer in the reservoir and is an additional leach Ghent.

Besides:

- as a hydraulic medium using sulfuric or nitric, or carbonic, or sulfuric acid or mixtures thereof.

- as a hydraulic medium use mixed solutions of sodium carbonate-hydrogen carbonate (Na ₂ CO ₃ + NaHCO ₃ ) or ammonium carbonate-hydrogen carbonate ((NH ₄ ) ₂ CO ₃ + NH ₄ HCO ₃ ), or sodium carbonate-hydroxide (Na ₂ CO ₃ + NaOH) or brine with sodium carbonate, saturated with CO ₂ .

- after the hydraulic medium is fed into the reservoir, an injection solution containing sand of a fraction of 0.5-2 mm is again fed.

- choose the direction of the injection and pumping wells with the possibility of their displacement relative to the vertical.

- for supplying a hydraulic medium to the formation, tubing wells are used.

- an oxygen-containing gas or liquid is supplied to the formation.

The figure shows a diagram of the implementation of the method, where 1 is the injection well, 2 is the reservoir, 3 is the injected solution, 4 is the productive solution, 5 is the pumping well, 6 is the hydrometallurgical redistribution unit, 7 is the solution mixer, 8 is the solution component, 9 is gate valve, 10 - collector, 11 - hydraulic medium capacity, 12 - hydraulic medium, 13 - high pressure pump, 14 - formation fractures

An example implementation of the invention is the method of extracting metal from ores, described below.

In the described embodiment of the invention, gold is used as a recoverable metal, which allows us to characterize the features of the invention in relation to technological processes for extracting metal from ores by underground leaching, in particular technology, which involves the sequential injection of a solution containing hydrogen chloride and sodium hypochlorite, pumping productive solutions through a system of pumping wells.

The method is as follows.

и Cl^- равна по величине и составляет 330 кДж/моль. Для серной кислоты: 84 кДж/моль H₂SO₄.In the injection well 1, the injected solution 3, containing hydrogen chloride and sodium hypochlorite, is fed into the formation 2. After filtering the injected solution 3 through the ore body of the formation 2 and saturating the injected solution 3 with mineral leaching products to form a productive solution 4, the productive solution 4 is pumped out through the pumping system 4 with a productive solution 5 fed into the hydrometallurgical processing unit 6, where the metal concentrate is extracted. As the capacity of the injected solution 3, a mixer of solution 7 can be used, in which the injected solution 3 is prepared by mixing the components of the solution 8. The injected solution 3 is fed through the valve 9 to the manifold 10. Into the reservoir 10 periodically, as the injected solution 3 in the formation 2 moves also serves from the tank of the hydraulic medium 11, the hydraulic medium 12 required by the technology, which can be used as sulfuric, nitric, carbonic or sulfuric acid or mixtures thereof, as well as mixed solutions of car sodium hydrogencarbonate (Na ₂ CO ₃ + NaHCO ₃ ), ammonium carbonate-carbonate ((NH ₄ ) ₂ CO ₃ + NH ₄ HCO ₃ ), sodium carbonate-hydroxide (Na ₂ CO ₃ + NaOH) or brine with sodium carbonate saturated with CO ₂ . The choice of the composition of the hydraulic medium is determined primarily by the mineral composition of the reservoir. The hydraulic medium 12 through the valve 9 is fed into the high pressure pump 13, and then into the reservoir 10, from which it is supplied under pressure above the pressure in the reservoir into the reservoir 2 through a system of injection wells 1. Once in the reservoir 2, the hydraulic medium 12 collides with the injected solution 3, previously filling the reservoir 2, resulting in a hydraulic shock, accompanied by an increase in temperature caused by the heat of hydration of the hydraulic medium 12 in the injected solution 3. The energy of ion hydration $$N{H}_{\mathrm{four}}^{+}$$

and Cl ^- is equal in magnitude and is 330 kJ / mol. For sulfuric acid: 84 kJ / mol H ₂ SO ₄ .

At pH <5.0, the equilibrium of the NaClO hydrolysis reaction shifts toward the release of molecular Cl ₂ , at pH less than 3, decomposition proceeds with the formation of molecular Cl ₂ , increased acidity inhibits hydrolysis and facilitates the oxidation of chloride ions to elemental chlorine.

The combination of these processes leads to the formation and further development of cracks 14 in the formation 2, increasing the washing surface of the minerals of the formation 2 with the injected solution 3, as well as activation of mass transfer processes at the interface between the liquid and solid phases, which leads to an increase in the productivity of the process of extracting metal from the ore formation 2, increasing the rate of leaching solution in the ore massif of the formation 2 from 0.5 to 2-4 meters per day, respectively, the intensity of the selection of the productive solution 5 from the pumping hole 4. In addition, When hydraulic medium 12 is fed into formation 2, injection solution 3 containing sand of a fraction of 0.5-2 mm can again be fed in order to prevent clogging of the filter zone of injection wells 1. The need for this operation depends on the rheological properties of formation 2, i.e., plastic deformations and rock mobility formation 2.

To increase productivity, choose the direction of the injection and pumping wells with the possibility of their displacement relative to the vertical with the formation of inclined injection 1 and pumping 4 wells containing an extended horizontal section with perforation. To this end, directional drilling of wells is carried out according to special profiles, which can vary so that the upper interval of the borehole of the inclined well is vertical, followed by a deviation in the designed azimuth. Given the high supply pressure of the hydraulic medium 12, pumping wells (not shown in the Figure) drilled at a certain distance from the injection wells 3 can be used to feed it into the formation 2. The hydraulic medium can also be supplied through the wells 1. Depending on the required valency of the metal contained in the minerals of the ore field of formation 2, oxygen-containing gas or liquid can also be supplied to formation 2 through wells 1, which create the required metal oxidation potential, thereby reducing the concentration of lots pumped in solution 3. For example, the additive may be effective oxygen scavenging air, the use of solutions of H ₂ O _2, NaClO, NaClO _3, KMnO ₄ or MnO ₂ slurry of finely divided.

The composition of the injected solution 3 includes hydrogen chloride - hydrochloric acid, which is necessary to prevent the deposition of gold and its partial sorption on clay minerals, as well as a solution of sodium hypochlorite, which can be produced directly at the place of application by electrolysis. Residual sodium chloride promotes more efficient leaching of metals. In particular, in gold deposits, product solution 5 is enriched with hydrogen tetrachloroaurate (III) (hydrochloric acid) - HAuCl ₄ according to the reactions:

When this free chlorine is formed by mixing in the reservoir 2 of the injected solution 3 and the hydraulic medium 12, which increases the acidity of the solution to pH 1.5-2.5. Chlorine is also formed as a result of the following chemical reactions of hypochlorite with hydrochloric acid:

To suppress hydrolysis (reduce the contribution of hydrolyzed forms below 1%), the condition [H ⁺ ] [Cl ^- ]> 10 ^-4 should be maintained, as indicated in [Mironov I.V., Tsvelodub L.D. Chlorohydroxocomplexes of gold (III) in aqueous alkaline solutions // Journal of Inorganic Chemistry. 2000, t. 45. No. 4. from. 706-711].

, важным процессом является диспропорционирование, которое регулирует соотношение между формами золота в разных степенях окисления:For gold (III), and, in particular, for $$AuC{l}_{\mathrm{four}}^{-}$$

, an important process is disproportionation, which regulates the ratio between the forms of gold in different degrees of oxidation:

, ^-lgK=-6.3 [Белеванцев В.И., Пещевицкий Б.И., Земсков С.В. Новые данные по химии соединений золота в растворах. // Известия Сибирского отделения АН СССР, сер. хим. наук. 1976. №4, вып. 2. с. 24-45].

, ^- logK = -6.3 [Belevantsev V.I., Peshchevitsky B.I., Zemskov S.V. New data on the chemistry of gold compounds in solutions. // Proceedings of the Siberian Branch of the Academy of Sciences of the USSR, ser. Chem. sciences. 1976. No. 4, no. 2. s. 24-45].

The high redox potential of HAuCl ₄ makes possible the electrochemical refining of gold (E. Wohlwill, 1874), the process by which the bulk of gold with a purity of about 99.99 is currently obtained.

до металлического золота в кислой среде используют железо (II), сернистый газ или сульфитсодержащие препараты, органические восстановители, гидразин N₂H₄ или его солиRecovery $$AuC{l}_{\mathrm{four}}^{-}$$

to metallic gold in an acidic environment, iron (II), sulfur dioxide or sulfite-containing preparations, organic reducing agents, hydrazine N ₂ H ₄ or its salts are used

Sulphite reduction is the most common. The process effectively takes place at room temperature in a strongly acidic (pH <1) environment, which prevents the precipitation of hydroxides of other metals [Paddefet R. Chemistry of gold. 1982. M .: World].

The choice of pressure of the hydraulic medium 12 is determined, first of all, by the mining conditions of the bed 2 and serves mainly for the formation of extended cracks as a result of hydraulic fracturing of the bed 2, which requires the use of pumping units that provide an injection speed of at least 4 cubic meters. m / min at a pressure of 40-100 MPa. If the pressure exceeds the horizontal component of the pressure in the reservoir, then a vertical crack is formed. In case of excess pressure in the reservoir 2, a horizontal crack is formed. The heterogeneity of the rock of formation 2 and the effect of the injected solution 3 leads to branching of cracks.

The appearance of water hammer in the collision of the hydraulic medium 12 and the injected fluid 3 creates a pressure jump (shock wave), the value of which is determined by the formula N.E. Zhukovsky:

where ΔР is the intensity of hydroblow, Pa;

ρ is the density of the liquid, kg / m ³ ;

ΔV is the speed jump, m / s;

C is the propagation velocity of the shock wave (sound) without taking into account the ductility of the walls, m / s.

From formula (5) it follows that at a hydraulic fluid velocity of 12 in the pipe v = 40 m / s, at the moment of collision with the front of the injected fluid 3, the pressure in it will increase by an amount equal to 4000-6400 kPa, sufficient for cracking in the formation rock 2.

The metal is extracted into the productive solution 5 by ion exchange during the controlled movement of the injected fluid 3 through the reservoir 2, previously hydrochemically activated by the above method. Thus, a pulsating-static regime is implemented with periodic flooding by a leaching reagent (injected liquid 3) of the ore bed 2 with natural and artificially created water permeability and subsequent supply of the hydraulic medium 12 and pumping the resulting productive solution 5 (filtrate) through the pumping wells 5.

For uranium ores, leaching is carried out on uranium deposits confined to flooded sedimentary rocks. In the injected solution 3 of the composition proposed in the invention, such uranium minerals are dissolved as: otenite: Ca [UO ₂ | PO ₄ ] ₂ · 10 (12-10) H ₂ O; uranospinite: Ca [UO ₂ | AsO ₄ ] ₂ · 10H ₂ O; zenerite: Cu [UO ₂ ] AsO ₄ ] ₂ × 10-16H ₂ O; uranofan Ca [UO2 (SiO3OH)] 2 · 5H ₂ O; carnotite K2 (UO2) 2 (VO4) 2 · 3H ₂ O; torbornite Cu (UO2) 2 (PO4) 2 · 12H ₂ O; tyuyamunit Ca (UO2) 2 (VO4) 2 · 80H ₂ O; casalite Pb [UO2 SiO4] · H ₂ O; Ningoite CaU (PO4) 2 · 2H ₂ O; davidite (Fe, Ce, U) (Ti, Fe, V, Cr) 3 (O, OH) 7, which in the main uranium ore deposits are represented by oxides (uranium tar, uraninite, coffinite), vanadates (carnotite and tyuyamunit) and complex titanates (brannerite and davitite).

The hydraulic medium 12 has two functions: as a hydraulic medium for the formation of hydraulic shock and as an additional leaching agent. The second function, mainly for economic and technological reasons, requires the use of sulfuric acid (for phosphate, silicate, and sulfur-containing rocks), nitric acid leaching (for rich ore concentrates of uranium, or for co-separation of thorium and REE from monazites). Nitric acid has the highest oxidizing potential as a reagent for leaching metals, but it is the most expensive, and nitrous gases during downhole leaching pose serious technical problems. Nitric acid can be used in a mixture with sulfuric acid as a powerful oxidizing agent.

For uranium-containing carbonate rocks, 3 mixtures of sodium carbonate-hydrogen carbonate (Na ₂ CO ₃ + NaHCO ₃ ), ammonium carbonate-ammonium carbonate ((NH ₄ ) ₂ CO ₃ + NH ₄ HCO ₃ ), carbonate- sodium hydroxide (Na ₂ CO ₃ + NaOH) or brine with sodium carbonate saturated with CO ₂ . The use of oxidizing agents can also be effective - additional purging with atmospheric oxygen, the use of solutions of H ₂ O ₂ , NaClO, NaClO ₃ , KMnO ₄ or a suspension of finely divided MnO ₂ .

Reducing the consumption of reagents and the selection of the composition of the injected liquid 3 can also minimize environmental damage.

Thus, this method will expand the functionality, increase reliability and performance, improve the economic performance of the method, technologies and systems based on it, reduce the harmful effects on the environment.

Claims (7)

1. A method of extracting metals from ores, including the sequential injection into the reservoir through a system of injection wells of a solution containing hydrogen chloride and sodium hypochlorite, pumping productive solutions through a system of pumping wells, characterized in that after the injection of the injection solution into the formation, pressure is supplied in excess of the pressure in the reservoir, the hydraulic medium that provides the pH of the solution pH 1.5-2.5, the formation of water hammer in the reservoir and is an additional leaching agent. 2. The method according to p. 1, characterized in that as the hydraulic medium using sulfuric, nitric, carbonic or sulfuric acid or mixtures thereof. 3. The method according to p. 1, characterized in that as the hydraulic medium using mixed solutions of sodium carbonate-bicarbonate (Na ₂ CO ₃ + NaHCO ₃ ), ammonium carbonate-bicarbonate ((NH ₄ ) ₂ CO ₃ + NH ₄ HCO ₃ ), sodium carbonate-hydroxide (Na ₂ CO ₃ + NaOH) or brine with sodium carbonate, saturated with CO ₂ . 4. The method according to p. 1, characterized in that after the hydraulic medium is fed into the reservoir, an injection solution containing sand of a fraction of 0.5-2 mm is again fed. 5. The method according to p. 1, characterized in that they select the direction of the injection and pumping wells with the possibility of their displacement relative to the vertical. 6. The method according to p. 1, characterized in that for supplying a hydraulic medium into the formation using pumping wells. 7. The method according to p. 1, characterized in that the reservoir additionally serves an oxygen-containing gas or liquid.

Images