Copper sulfide ore dump leaching method with low ammonia consumption

Abstract

According to the low-ammonia-consumption copper sulfide ore dump leaching method, through closed operation of a dump leaching-extraction whole system, ammonia volatilization loss can be controlled, meanwhile, natural rainfall can be prevented from entering a leaching system, ammonia loss caused by water expansion is avoided, and the formation of the temperature beneficial to leaching is facilitated. And bivalent copper is regenerated by adding a proper oxidizing agent or blowing in oxygen, non-oxygen gas can be prevented from being introduced into a closed system, ammonia escape loss can be reduced, and oxidation-reduction potential beneficial to chalcopyrite leaching can be formed by controlling the amount of the oxidizing agent and the amount of the oxygen, so that chalcopyrite can be leached continuously. Through gradient ammonia supply in different leaching stages, the loss of ammonia entrained in the leaching residues can be reduced. Ammonia can be recycled by extracting and completely returning raffinate to a leaching system.

Description

Technical Field

[0001] The invention relates to the technical field of copper sulfide ore leaching, and in particular to a copper sulfide ore heap leaching method with low ammonia consumption. Background Art

[0002] Primary copper sulfide ore with chalcopyrite as the main copper mineral is the most important raw material for copper smelting. At present, it is mainly recovered by traditional flotation-pyrometallurgy process, but due to the high cost of traditional process, it is not suitable for low-grade copper sulfide ore. Low-cost bio-heap leaching technology has been successfully applied to the recovery of secondary copper sulfide ore resources, but due to the slow leaching kinetics of chalcopyrite in acidic high-iron medium, the bio-heap leaching technology of primary copper sulfide ore has not yet been widely used in commercial applications. However, the leaching kinetics of chalcopyrite in alkaline ammonium salt medium is significantly higher than that in acidic high-iron medium, which shows good prospects for the application of ammonia copper leaching technology in the recovery of primary copper sulfide ore.

[0003] The industrial practice of copper recovery by ammonia leaching has a history of more than 100 years. The first ammonia copper leaching project started in 1915, using a stirring leaching process to treat oxidized copper ore; the Arbiter stirring ammonia leaching process was used to treat sulfide copper concentrates mainly composed of chalcocite in 1970. The early ammonia copper leaching process treated oxidized ores and secondary sulfide ores, using a stirring leaching process and ammonia evaporation to recover ammonia. Due to the difficulty of ammonia recovery operation and high cost, these ammonia copper leaching plants have been closed one after another.

[0004] Ammonia leaching of chalcopyrite faces the common challenge of ammonia process - high ammonia consumption, and the problem of chalcopyrite leaching rate. In order to improve the copper leaching rate, CN101730753A discloses a method of first aging and then ammonia leaching of copper, nickel, zinc and other metals; CN1327012C proposes an ammonia leaching method with the addition of a strong oxidant, sodium hypochlorite, to strengthen the leaching of chalcopyrite in oxygen-sulfur mixed ore; CN1320137C proposes a method for leaching chalcopyrite with a composite leaching agent composed of a leaching agent, an oxidant, and a pulp potential control agent; CN111549220A proposes an ammonia leaching method for sulfide copper-nickel ore with the addition of a reducing agent. These methods can all increase the leaching rate of chalcopyrite, but the ammonia volatilization loss is serious when leaching is stirred at a higher temperature; the amount of additives used is large and the cost is high, and the use of a chlorine-containing leaching agent is not conducive to the subsequent copper electrowinning, and no effective measures to reduce ammonia consumption have been proposed.

[0005] In order to reduce ammonia consumption, CN1718786A discloses a method for stirring ammonia leaching of copper oxide at room temperature, wherein the raffinate is recycled and ammonia is not evaporated. However, the solid-liquid separation operation after stirring leaching causes water expansion, and the problem of high ammonia consumption has not been solved. CN102703701A discloses a method for treating copper oxide by combining stirring ammonia leaching with ammonia leaching in a percolation tank, which uses a fully closed process to reduce ammonia volatilization losses. However, due to the use of a stirring leaching process, the problem of ammonia loss caused by water expansion cannot be solved. CN102703700A proposes a method for segmented ammonia leaching and diversion extraction of copper oxide, which reduces ammonia consumption, but does not solve the problem of ammonia loss caused by water expansion. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention aims to provide a heap leaching method for copper sulfide ore with low ammonia consumption.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A method for heap leaching of copper sulfide ore with low ammonia consumption comprises the following steps:

[0009] S1. Crushing the copper sulfide ore and building a heap on the heap leaching site, then arranging a drip pipe on the heap, and then covering the heap with a sealing film;

[0010] S2, connecting the dripping pipe to the low concentration ammonia solution container, the medium concentration ammonia solution container and the high concentration ammonia solution container respectively, the low concentration ammonia solution container, the medium concentration ammonia solution container and the high concentration ammonia solution container are in a sealed state, and contain the low concentration ammonia solution, the medium concentration ammonia solution and the high concentration ammonia solution respectively;

[0011] S3. At different stages of heap leaching, ammonia solutions of different concentrations are dripped onto the ore heap by using a dripping pipe, wherein, at the initial stage of heap leaching, a high-concentration ammonia solution is dripped onto the ore heap, at the middle stage of heap leaching, a medium-concentration ammonia solution is dripped onto the ore heap, and at the final stage of heap leaching, a low-concentration ammonia solution is dripped onto the ore heap; the copper-containing leaching solution flows out into a qualified liquid pool, and the qualified liquid pool is in a sealed state;

[0012] S4. Pumping the leachate in the qualified liquid pool to an extraction device for extraction, and returning the obtained raffinate to a low-concentration ammonia solution container, a medium-concentration ammonia solution container and / or a high-concentration ammonia solution container for recycling; the mixing and settling tank of the extraction device is in a sealed state.

[0013] Furthermore, during the heap leaching process, the temperature of the ore heap is maintained above 20°C.

[0014] Furthermore, the copper sulfide ore includes any one of primary copper sulfide ore, secondary copper sulfide ore, copper-nickel-cobalt sulfide ore, and oxygen-sulfur mixed ore, the mass content of Cu is 0.1-3%, and the particle size of the crushed ore is P 80=3mm-300mm.

[0015] Furthermore, in step S4, before the raffinate is returned to the low-concentration ammonia solution container, the medium-concentration ammonia solution container and / or the high-concentration ammonia solution container, the pH value of the raffinate is adjusted to 8.0-10.

[0016] Furthermore, one or more of ammonium sulfate, ammonium carbonate, ammonium bicarbonate and aqueous ammonia are used to adjust the pH of the raffinate.

[0017] Furthermore, during the heap leaching process, an oxidant is added to the dripping low concentration ammonia solution, medium concentration ammonia solution or high concentration ammonia solution, and / or oxygen is supplied to the bottom of the ore heap through an oxygen supply pipe to regenerate Cu 2+ , increasing the redox potential of the leaching solution.

[0018] Furthermore, the oxidant is one or more of hydrogen peroxide, sodium peroxide, calcium peroxide, ammonium persulfate, sodium persulfate, and calcium persulfate; and the oxygen supply is industrial oxygen.

[0019] Furthermore, the redox potential of the leaching solution is controlled by controlling the amount of oxidant added or the amount of oxygen supplied, so that the redox potential of the leaching solution is above 200 mV (vs. SHE).

[0020] Furthermore, the total ammonia concentration of the high-concentration ammonia solution is 2-3 mol / L, the total ammonia concentration of the medium-concentration ammonia solution is 0.5-2 mol / L, and the total ammonia concentration of the low-concentration ammonia solution is 0-0.5 mol / L.

[0021] The beneficial effects of the present invention are as follows: the present invention can control ammonia volatilization loss by operating the whole heap leaching-extraction system in a closed manner, and can isolate natural rainfall from entering the leaching system, thereby avoiding ammonia loss due to water expansion, and helping to form a temperature that is conducive to leaching. By adding a suitable oxidant or bubbling oxygen to regenerate divalent copper, it is possible to avoid introducing non-oxygen gas into the closed system, reduce ammonia escape loss, and by controlling the amount of oxidant and oxygen, a redox potential that is conducive to leaching of chalcopyrite can be formed, and chalcopyrite can be continuously leached. By supplying ammonia in a gradient at different leaching stages, the loss of ammonia entrained in the leaching residue can be reduced. Ammonia can be recycled by extracting and returning all the raffinate to the leaching system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the implementation of the method of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to this embodiment.

[0024] A method for heap leaching of copper sulfide ore with low ammonia consumption comprises the following steps:

[0025] S1, such as Figure 1 As shown, the copper sulfide ore is crushed and piled up on the heap leaching site, then drip pipes are arranged on the ore pile, and then the ore pile is covered with a sealing film;

[0026] S2, connecting the dripping pipe to the low concentration ammonia solution container, the medium concentration ammonia solution container and the high concentration ammonia solution container respectively, the low concentration ammonia solution container, the medium concentration ammonia solution container and the high concentration ammonia solution container are in a sealed state, and contain the low concentration ammonia solution, the medium concentration ammonia solution and the high concentration ammonia solution respectively;

[0027] S3. At different stages of heap leaching, ammonia solutions of different concentrations are dripped onto the ore heap by using a dripping pipe, wherein, at the initial stage of heap leaching, a high-concentration ammonia solution is dripped onto the ore heap, at the middle stage of heap leaching, a medium-concentration ammonia solution is dripped onto the ore heap, and at the final stage of heap leaching, a low-concentration ammonia solution is dripped onto the ore heap; the copper-containing leaching solution flows out into a qualified liquid pool, and the qualified liquid pool is in a sealed state;

[0028] S4. Pumping the leachate in the qualified liquid pool to an extraction device for extraction, and returning the obtained raffinate to a low-concentration ammonia solution container, a medium-concentration ammonia solution container and / or a high-concentration ammonia solution container for recycling; the mixing and settling tank of the extraction device is in a sealed state.

[0029] Furthermore, during the heap leaching process, the temperature of the ore heap is maintained above 20°C.

[0030] Furthermore, the copper sulfide ore includes any one of primary copper sulfide ore, secondary copper sulfide ore, copper-nickel-cobalt sulfide ore, and oxygen-sulfur mixed ore, the mass content of Cu is 0.1-3%, and the particle size of the crushed ore is P 80 =3mm-300mm.

[0031] Furthermore, in step S4, before the raffinate is returned to the low-concentration ammonia solution container, the medium-concentration ammonia solution container and / or the high-concentration ammonia solution container, the pH value of the raffinate is adjusted to 8.0-10.

[0032] Furthermore, one or more of ammonium sulfate, ammonium carbonate, ammonium bicarbonate and aqueous ammonia are used to adjust the pH of the raffinate.

[0033] Furthermore, during the heap leaching process, an oxidant is added to the dripping low concentration ammonia solution, medium concentration ammonia solution or high concentration ammonia solution, and / or oxygen is supplied to the bottom of the ore heap through an oxygen supply pipe to regenerate Cu 2+ , increasing the redox potential of the leaching solution.

[0034] It should be noted that Cu 2+It is the most important oxidant of chalcopyrite, Cu 2+ Chalcopyrite is oxidized and then reduced to Cu 1+ , Cu needs to be regenerated in time 2+ , in order to ensure the continuous leaching of chalcopyrite. By adding oxidants or blowing in oxygen, as shown in reactions (1) and (2), not only the oxidant Cu 2+ , while avoiding the introduction of non-oxygen gases into the closed system to reduce ammonia escape losses:

[0035] Cu 1+ +H2O2+H + =Cu 2+ +2H2O (1)

[0036] Cu 1+ +O2+H + =Cu 2+ +H2O (2)

[0037] Furthermore, the oxidant is one or more of hydrogen peroxide, sodium peroxide, calcium peroxide, ammonium persulfate, sodium persulfate, and calcium persulfate; and the oxygen supply is industrial oxygen.

[0038] Furthermore, the redox potential of the leaching solution is controlled by controlling the amount of oxidant added or the amount of oxygen supplied, so that the redox potential of the leaching solution is above 200 mV (vs. SHE).

[0039] It should be noted that the ammonia oxidation of chalcopyrite is an electrochemical reaction. The leaching kinetics is strongly related to the redox potential of the solution. The addition of an appropriate amount of oxidant or the introduction of oxygen to regenerate Cu 2+ , raise the redox potential of the solution to above the electrostatic potential of chalcopyrite to ensure continuous copper leaching. The redox potential mainly depends on the activity ratio of the copper ion pair Cu 2+ / Cu 1 + Therefore, the redox potential of the leaching solution can be controlled by controlling the amount of oxidant added or the amount of oxygen bubbled in.

[0040] Furthermore, the total ammonia concentration of the high-concentration ammonia solution is 2-3 mol / L, the total ammonia concentration of the medium-concentration ammonia solution is 0.5-2 mol / L, and the total ammonia concentration of the low-concentration ammonia solution is 0-0.5 mol / L.

[0041] Example 1

[0042] The ore sample is a primary copper sulfide ore, with chalcopyrite as the main copper mineral, containing a small amount of bornite and chalcocite; other sulfide minerals are mainly pyrite; the gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu 1.2%, S 2-4.69%, Fe 6.5%, CaO 8.95%, MgO 6.75%. The original copper sulfide ore is crushed to obtain a particle size of P 80 =3mm sample.

[0043] In this embodiment, a column leaching system is used to simulate heap leaching, and a liquid collecting barrel is used to simulate a qualified liquid pool. After the ore is piled into the leaching column, the leaching column is sealed with a HDPE membrane, and the liquid collecting barrel and the extraction device are sealed with a cover to reduce ammonia volatility, keep the ore pile warm, and control the water balance. The ammonia solution is a mixed solution of ammonium bicarbonate and ammonium carbonate, with a pH of 8.5. In the early stage of leaching, a high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore; in the middle stage of heap leaching, a medium-concentration ammonia solution with a total ammonia concentration of 1 mol / L is used to drip the ore; and in the late stage of heap leaching, a low-concentration ammonia solution with a total ammonia concentration of 0.25 mol / L is used to drip the ore to reduce the loss of ammonia in the heap leaching residue.

[0044] During the heap leaching process, the reaction temperature was controlled at 30°C by heating the ammonia solution and adding hydrogen peroxide to the ammonia solution to regenerate Cu. 2+ , the redox potential of the leaching solution was adjusted to 350 mV (vs. SHE) to promote copper leaching.

[0045] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 81.4% and the ammonia consumption was 3kg / t.

[0046] Example 2

[0047] The ore sample is a primary copper sulfide ore, with chalcopyrite as the main copper mineral, containing a small amount of bornite and chalcocite; other sulfide minerals are mainly pyrite; the gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu 1.2%, S 2- 4.69%, Fe 6.5%, CaO 8.95%, MgO 6.75%. The original copper sulfide ore is crushed to obtain a particle size of P 80 =3mm sample.

[0048] In this embodiment, a column leaching system is used to simulate heap leaching, and a liquid collecting barrel is used to simulate a qualified liquid pool. After the ore is piled into the leaching column, the leaching column is sealed with a HDPE membrane, and the liquid collecting barrel and the extraction device are sealed with a cover to reduce ammonia volatility, keep the ore pile warm, and control the water balance. The ammonia solution is a mixed solution of ammonium bicarbonate and ammonium carbonate, with a pH of 8.5. In the early stage of leaching, a high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore; in the middle stage of heap leaching, a medium-concentration ammonia solution with a total ammonia concentration of 1 mol / L is used to drip the ore; and in the late stage of heap leaching, a low-concentration ammonia solution with a total ammonia concentration of 0.25 mol / L is used to drip the ore to reduce the loss of ammonia in the heap leaching residue.

[0049] During the heap leaching process, the reaction temperature is controlled at 20°C by heating the ammonia solution and adding hydrogen peroxide to the ammonia solution to regenerate Cu 2+ ; The redox potential of the leaching solution was adjusted to 350 mV (vs. SHE) to promote copper leaching.

[0050] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 68.2% and the ammonia consumption was 2.3kg / t.

[0051] Example 3

[0052] The ore sample is a primary copper sulfide ore, with chalcopyrite as the main copper mineral, containing a small amount of bornite and chalcocite; other sulfide minerals are mainly pyrite; the gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu 1.2%, S 2- 4.69%, Fe 6.5%, CaO 8.95%, MgO 6.75%. The original copper sulfide ore is crushed to obtain a particle size of P 80 =3mm sample.

[0053] In this embodiment, a column leaching system is used to simulate heap leaching, and a liquid collecting barrel is used to simulate a qualified liquid pool. After the ore is piled into the leaching column, the leaching column is sealed with a HDPE membrane, and the liquid collecting barrel and the extraction device are sealed with a cover to reduce ammonia volatility, keep the ore pile warm, and control the water balance. The ammonia solution is a mixed solution of ammonium bicarbonate and ammonium carbonate, with a pH of 8.5. In the early stage of leaching, a high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore; in the middle stage of heap leaching, a medium-concentration ammonia solution with a total ammonia concentration of 1 mol / L is used to drip the ore; and in the late stage of heap leaching, a low-concentration ammonia solution with a total ammonia concentration of 0.25 mol / L is used to drip the ore to reduce the loss of ammonia in the heap leaching residue.

[0054] During the heap leaching process, the reaction temperature is controlled at 25°C by heating the ammonia solution and adding hydrogen peroxide to the ammonia solution to regenerate Cu 2+; The redox potential of the leaching solution was adjusted to 350 mV (vs. SHE) to promote copper leaching.

[0055] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 74.5% and the ammonia consumption was 2.5 kg / t.

[0056] Example 4

[0057] The ore sample is a primary copper sulfide ore, with chalcopyrite as the main copper mineral, containing a small amount of bornite and chalcocite; other sulfide minerals are mainly pyrite; the gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu 1.2%, S 2- 4.69%, Fe 6.5%, CaO 8.95%, MgO 6.75%. The original copper sulfide ore is crushed to obtain a particle size of P 80 =3mm sample.

[0058] In this embodiment, a column leaching system is used to simulate heap leaching, and a liquid collecting barrel is used to simulate a qualified liquid pool. After the ore is piled into the leaching column, the leaching column is sealed with a HDPE membrane, and the liquid collecting barrel and the extraction device are sealed with a cover to reduce ammonia volatility, keep the ore pile warm, and control the water balance. The ammonia solution is a mixed solution of ammonium bicarbonate and ammonium carbonate, with a pH of 8.5. In the early stage of leaching, a high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore; in the middle stage of heap leaching, a medium-concentration ammonia solution with a total ammonia concentration of 1 mol / L is used to drip the ore; and in the late stage of heap leaching, a low-concentration ammonia solution with a total ammonia concentration of 0.25 mol / L is used to drip the ore to reduce the loss of ammonia in the heap leaching residue.

[0059] During the heap leaching process, the reaction temperature was controlled at 35°C by heating the ammonia solution and adding hydrogen peroxide to the ammonia solution to regenerate Cu. 2+ ; The redox potential of the leaching solution was adjusted to 350 mV (vs. SHE) to promote copper leaching.

[0060] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 85.9% and the ammonia consumption was 3.5 kg / t.

[0061] Example 5

[0062] The ore sample is a primary copper sulfide ore, with chalcopyrite as the main copper mineral, containing a small amount of bornite and chalcocite; other sulfide minerals are mainly pyrite; the gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu 1.2%, S 2- 4.69%, Fe 6.5%, CaO 8.95%, MgO 6.75%. The original copper sulfide ore is crushed to obtain a particle size of P 80 =3mm sample.

[0063] In this embodiment, a column leaching system is used to simulate heap leaching, and a liquid collecting barrel is used to simulate a qualified liquid pool. After the ore is piled into the leaching column, the leaching column is sealed with a HDPE membrane, and the liquid collecting barrel and the extraction device are sealed with a cover to reduce ammonia volatility, keep the ore pile warm, and control the water balance. The ammonia solution is a mixed solution of ammonium bicarbonate and ammonium carbonate, with a pH of 8.5. In the early stage of leaching, a high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore; in the middle stage of heap leaching, a medium-concentration ammonia solution with a total ammonia concentration of 1 mol / L is used to drip the ore; and in the late stage of heap leaching, a low-concentration ammonia solution with a total ammonia concentration of 0.25 mol / L is used to drip the ore to reduce the loss of ammonia in the heap leaching residue.

[0064] During the heap leaching process, the reaction temperature was controlled at 30°C by heating the ammonia solution and adding hydrogen peroxide to the ammonia solution to regenerate Cu. 2+ , the redox potential of the leaching solution was adjusted to 200 mV (vs. SHE) to promote copper leaching.

[0065] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 64.8% and the ammonia consumption was 3.1 kg / t.

[0066] Example 6

[0067] The ore sample is a primary copper sulfide ore, with chalcopyrite as the main copper mineral, containing a small amount of bornite and chalcocite; other sulfide minerals are mainly pyrite; the gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu 1.2%, S 2- 4.69%, Fe 6.5%, CaO 8.95%, MgO 6.75%. The original copper sulfide ore is crushed to obtain a particle size of P 80 =3mm sample.

[0068] In this embodiment, a column leaching system is used to simulate heap leaching, and a liquid collecting barrel is used to simulate a qualified liquid pool. After the ore is piled into the leaching column, the leaching column is sealed with a HDPE membrane, and the liquid collecting barrel and the extraction device are sealed with a cover to reduce ammonia volatility, keep the ore pile warm, and control the water balance. The ammonia solution is a mixed solution of ammonium carbonate and ammonia water, with a pH of 8. In the early stage of leaching, a high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore; in the middle stage of heap leaching, a medium-concentration ammonia solution with a total ammonia concentration of 1 mol / L is used to drip the ore; and in the late stage of heap leaching, a low-concentration ammonia solution with a total ammonia concentration of 0.25 mol / L is used to drip the ore to reduce the loss of ammonia in the heap leaching residue.

[0069] During the heap leaching process, the reaction temperature was controlled at 30°C by heating the ammonia solution and adding hydrogen peroxide to the ammonia solution to regenerate Cu. 2+ , the redox potential of the leaching solution was adjusted to 350 mV (vs. SHE) to promote copper leaching.

[0070] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 75.2% and the ammonia consumption was 2.5 kg / t.

[0071] Example 7

[0072] The ore sample is a primary copper sulfide ore, with chalcopyrite as the main copper mineral, containing a small amount of bornite and chalcocite; other sulfide minerals are mainly pyrite; the gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu 1.2%, S 2- 4.69%, Fe 6.5%, CaO 8.95%, MgO 6.75%. The original copper sulfide ore is crushed to obtain a particle size of P 80 =3mm sample.

[0073] In this embodiment, a column leaching system is used to simulate heap leaching, and a liquid collecting barrel is used to simulate a qualified liquid pool. After the ore is piled into the leaching column, the leaching column is sealed with a HDPE membrane, and the liquid collecting barrel and the extraction device are sealed with a cover to reduce ammonia volatility, keep the ore pile warm, and control the water balance. The ammonia solution is a mixed solution of ammonium carbonate and ammonia water, with a pH of 10. In the early stage of leaching, a high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore; in the middle stage of heap leaching, a medium-concentration ammonia solution with a total ammonia concentration of 1 mol / L is used to drip the ore; and in the late stage of heap leaching, a low-concentration ammonia solution with a total ammonia concentration of 0.25 mol / L is used to drip the ore to reduce the loss of ammonia in the heap leaching residue.

[0074] During the heap leaching process, the reaction temperature was controlled at 30°C by heating the ammonia solution and adding hydrogen peroxide to the ammonia solution to regenerate Cu. 2+, the redox potential of the leaching solution was adjusted to 350 mV (vs. SHE) to promote copper leaching.

[0075] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 87.2% and the ammonia consumption was 5.5 kg / t.

[0076] Example 8

[0077] The ore sample is a primary copper sulfide ore, with chalcopyrite as the main copper mineral, containing a small amount of bornite and chalcocite; other sulfide minerals are mainly pyrite; the gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu 1.2%, S 2- 4.69%, Fe 6.5%, CaO 8.95%, MgO 6.75%. The original copper sulfide ore is crushed to obtain a particle size of P 80 =3mm sample.

[0078] In this embodiment, a column leaching system is used to simulate heap leaching, and a liquid collecting barrel is used to simulate a qualified liquid pool. After the ore is piled into the leaching column, the leaching column is sealed with a HDPE membrane, and the liquid collecting barrel and the extraction device are sealed with a cover to reduce ammonia volatility, keep the ore pile warm, and control the water balance. The ammonia solution is a mixed solution of ammonium bicarbonate and ammonium carbonate, with a pH of 8.5. In the early stage of leaching, a high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore; in the middle stage of heap leaching, a medium-concentration ammonia solution with a total ammonia concentration of 1 mol / L is used to drip the ore; and in the late stage of heap leaching, a low-concentration ammonia solution with a total ammonia concentration of 0.25 mol / L is used to drip the ore to reduce the loss of ammonia in the heap leaching residue.

[0079] During the heap leaching process, the reaction temperature is controlled at 30°C by heating the ammonia solution and sodium persulfate is added to the ammonia solution to regenerate Cu 2+ , the redox potential of the leaching solution was adjusted to 350 mV (vs. SHE) to promote copper leaching.

[0080] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 80.5% and the ammonia consumption was 3.1 kg / t.

[0081] Example 9

[0082] The ore sample is a primary copper sulfide ore, with chalcopyrite as the main copper mineral, containing a small amount of bornite and chalcocite; other sulfide minerals are mainly pyrite; the gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu 1.2%, S 2- 4.69%, Fe 6.5%, CaO 8.95%, MgO 6.75%. The original copper sulfide ore is crushed to obtain a particle size of P 80 =3mm sample.

[0083] In this embodiment, a column leaching system is used to simulate heap leaching, and a liquid collecting barrel is used to simulate a qualified liquid pool. After the ore is piled into the leaching column, the leaching column is sealed with a HDPE membrane, and the liquid collecting barrel and the extraction device are sealed with a cover to reduce ammonia volatility, keep the ore pile warm, and control the water balance. The ammonia solution is a mixed solution of ammonium bicarbonate and ammonium carbonate, with a pH of 8.5. In the early stage of leaching, a high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore; in the middle stage of heap leaching, a medium-concentration ammonia solution with a total ammonia concentration of 1 mol / L is used to drip the ore; and in the late stage of heap leaching, a low-concentration ammonia solution with a total ammonia concentration of 0.25 mol / L is used to drip the ore to reduce the loss of ammonia in the heap leaching residue.

[0084] During the heap leaching process, the reaction temperature is controlled at 30°C by heating the ammonia solution and blowing oxygen into the ore to regenerate Cu 2+ , the redox potential of the leaching solution was adjusted to 350 mV (vs. SHE) to promote copper leaching.

[0085] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 78.4% and the ammonia consumption was 3.5 kg / t.

[0086] Example 10

[0087] The ore sample is a primary copper sulfide ore, with chalcopyrite as the main copper mineral, containing a small amount of bornite and chalcocite; other sulfide minerals are mainly pyrite; the gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu 1.2%, S 2- 4.69%, Fe 6.5%, CaO 8.95%, MgO 6.75%. The original copper sulfide ore is crushed to obtain a particle size of P 80 =10mm sample.

[0088] In this embodiment, a column leaching system is used to simulate heap leaching, and a liquid collecting barrel is used to simulate a qualified liquid pool. After the ore is piled into the leaching column, the leaching column is sealed with a HDPE membrane, and the liquid collecting barrel and the extraction device are sealed with a cover to reduce ammonia volatility, keep the ore pile warm, and control the water balance. The ammonia solution is a mixed solution of ammonium bicarbonate and ammonium carbonate, with a pH of 8.5. In the early stage of leaching, a high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore; in the middle stage of heap leaching, a medium-concentration ammonia solution with a total ammonia concentration of 1 mol / L is used to drip the ore; and in the late stage of heap leaching, a low-concentration ammonia solution with a total ammonia concentration of 0.25 mol / L is used to drip the ore to reduce the loss of ammonia in the heap leaching residue.

[0089] During the heap leaching process, the reaction temperature was controlled at 30°C by heating the ammonia solution and adding hydrogen peroxide to the ammonia solution to regenerate Cu. 2+ , the redox potential of the leaching solution was adjusted to 350 mV (vs. SHE) to promote copper leaching.

[0090] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 70.4% and the ammonia consumption was 3.2kg / t.

[0091] Embodiment 11

[0092] The ore sample is an oxygen-sulfur mixed copper ore. The main copper sulfide mineral is chalcopyrite, which contains a small amount of bornite and chalcocite. The main copper oxide minerals are basic copper carbonate and azurite. Other sulfide minerals are mainly pyrite. The gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu 1.3%, AsCu 0.75%, S 2- 3.69%, Fe3.5%, CaO 9.95%, MgO 8.75%. The oxygen-sulfur mixed copper ore is crushed to obtain a particle size of P 80 =300mm sample.

[0093] In this embodiment, a thousand-ton industrial small pile is used for leaching. After the ore is piled in the stockpile, the dripping pipeline is arranged, the ore pile is sealed with HDPE membrane, and the qualified liquid pool and extraction device are covered and sealed to reduce ammonia volatility, insulate the ore pile and control the water balance. The ammonia solution is a mixed solution of ammonium bicarbonate and ammonium carbonate, with a pH of 8.5. In the early stage of leaching, a high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore; in the middle stage of heap leaching, a medium-concentration ammonia solution with a total ammonia concentration of 1 mol / L is used to drip the ore; and in the final stage of heap leaching, a low-concentration ammonia solution with a total ammonia concentration of 0.25 mol / L is used to drip the ore to reduce the loss of ammonia in the heap leaching residue.

[0094] During the heap leaching process, the reaction temperature was controlled at 30°C by heating the ammonia solution and adding hydrogen peroxide to the ammonia solution to regenerate Cu. 2+ , the redox potential of the leaching solution was adjusted to 350 mV (vs. SHE) to promote copper leaching.

[0095] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 74.4% and the ammonia consumption was 4.5 kg / t.

[0096] Comparative Example 1

[0097] The ore sample is a primary copper sulfide ore, with chalcopyrite as the main copper mineral, containing a small amount of bornite and chalcocite; other sulfide minerals are mainly pyrite; the gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu 1.2%, S 2- 4.69%, Fe 6.5%, CaO 8.95%, MgO 6.75%. The original copper sulfide ore is crushed to obtain a particle size of P 80 =3mm sample.

[0098] In this comparative example, a column leaching system is used to simulate heap leaching, and a liquid collecting barrel is used to simulate a qualified liquid pool. After the ore is piled into the leaching column, the leaching column is sealed with a HDPE membrane, and the liquid collecting barrel and the extraction device are sealed with a cover to reduce ammonia volatility, keep the ore pile warm, and control the water balance. The ammonia solution is a mixed solution of ammonium bicarbonate and ammonium carbonate, with a pH of 8.5. In the early stage of leaching, a high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore; in the middle stage of heap leaching, a medium-concentration ammonia solution with a total ammonia concentration of 1 mol / L is used to drip the ore; and in the late stage of heap leaching, a low-concentration ammonia solution with a total ammonia concentration of 0.25 mol / L is used to drip the ore to reduce the loss of ammonia in the heap leaching residue.

[0099] During the heap leaching process, the reaction temperature was controlled at 30°C by heating the ammonia solution and adding hydrogen peroxide to the ammonia solution to regenerate Cu. 2+ , the redox potential of the leaching solution was adjusted to 0 mV (vs. SHE).

[0100] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 6.3% and the ammonia consumption was 3.1 kg / t.

[0101] Comparative Example 2

[0102] The ore sample is a primary copper sulfide ore, with chalcopyrite as the main copper mineral, containing a small amount of bornite and chalcocite; other sulfide minerals are mainly pyrite; the gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu 1.2%, S 2- 4.69%, Fe 6.5%, CaO 8.95%, MgO 6.75%. The original copper sulfide ore is crushed to obtain a particle size of P 80 =3mm sample.

[0103] In this comparative example, a column leaching system is used to simulate heap leaching, and a liquid collecting barrel is used to simulate a qualified liquid pool. After the ore is piled into the leaching column, the leaching column is sealed with a HDPE membrane, and the liquid collecting barrel and the extraction device are sealed with a cover to reduce ammonia volatility, keep the ore pile warm, and control the water balance. The ammonia solution is a mixed solution of ammonium bicarbonate and ammonium carbonate, with a pH of 8.5. In the early stage of leaching, a high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore; in the middle stage of heap leaching, a medium-concentration ammonia solution with a total ammonia concentration of 1 mol / L is used to drip the ore; and in the late stage of heap leaching, a low-concentration ammonia solution with a total ammonia concentration of 0.25 mol / L is used to drip the ore to reduce the loss of ammonia in the heap leaching residue.

[0104] During the heap leaching process, the reaction temperature was controlled at 30°C by heating the ammonia solution and adding hydrogen peroxide to the ammonia solution to regenerate Cu. 2+ , the redox potential of the leaching solution was regulated to 100 mV (vs. SHE).

[0105] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 30.2% and the ammonia consumption was 3.0 kg / t.

[0106] Comparative Example 3

[0107] The ore sample is a primary copper sulfide ore, with chalcopyrite as the main copper mineral, containing a small amount of bornite and chalcocite; other sulfide minerals are mainly pyrite; the gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu 1.2%, S 2- 4.69%, Fe 6.5%, CaO 8.95%, MgO 6.75%. The original copper sulfide ore is crushed to obtain a particle size of P 80 =3mm sample.

[0108] In this comparative example, a column leaching system is used to simulate heap leaching, and a liquid collecting barrel is used to simulate a qualified liquid pool. After the ore is piled into the leaching column, the leaching column is sealed with a HDPE membrane, and the liquid collecting barrel and the extraction device are sealed with a cover to reduce ammonia volatility, keep the ore pile warm, and control the water balance. The ammonia solution is a mixed solution of ammonium bicarbonate and ammonium carbonate, with a pH of 7. In the early stage of leaching, a high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore; in the middle stage of heap leaching, a medium-concentration ammonia solution with a total ammonia concentration of 1 mol / L is used to drip the ore; and in the late stage of heap leaching, a low-concentration ammonia solution with a total ammonia concentration of 0.25 mol / L is used to drip the ore to reduce the loss of ammonia in the heap leaching residue.

[0109] During the heap leaching process, the reaction temperature was controlled at 30°C by heating the ammonia solution and adding hydrogen peroxide to the ammonia solution to regenerate Cu. 2+ , the redox potential of the leaching solution was regulated to 350 mV (vs. SHE).

[0110] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 35.6% and the ammonia consumption was 2.1 kg / t.

[0111] Comparative Example 4

[0112] The ore sample is a primary copper sulfide ore, with chalcopyrite as the main copper mineral, containing a small amount of bornite and chalcocite; other sulfide minerals are mainly pyrite; the gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu 1.2%, S 2- 4.69%, Fe 6.5%, CaO 8.95%, MgO 6.75%. The original copper sulfide ore is crushed to obtain a particle size of P 80 =3mm sample.

[0113] In this comparative example, a column leaching system is used to simulate heap leaching, and a liquid collecting barrel is used to simulate a qualified liquid pool. After the ore is piled into the leaching column, the leaching column is sealed with a HDPE membrane, and the liquid collecting barrel and the extraction device are sealed with a cover to reduce ammonia volatility, keep the ore pile warm, and control the water balance. The ammonia solution is a mixed solution of ammonium bicarbonate and ammonium carbonate, with a pH of 8.5. In the early stage of leaching, a high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore; in the middle stage of heap leaching, a medium-concentration ammonia solution with a total ammonia concentration of 1 mol / L is used to drip the ore; and in the late stage of heap leaching, a low-concentration ammonia solution with a total ammonia concentration of 0.25 mol / L is used to drip the ore to reduce the loss of ammonia in the heap leaching residue.

[0114] During the heap leaching process, the reaction temperature is controlled at 30°C by heating the ammonia solution and blowing air through the ore to regenerate Cu 2 +, the redox potential of the leaching solution was regulated to 350 mV (vs. SHE).

[0115] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 68.5% and the ammonia consumption was 12kg / t.

[0116] Comparative Example 5

[0117] The ore sample is a primary copper sulfide ore, with chalcopyrite as the main copper mineral, containing a small amount of bornite and chalcocite; other sulfide minerals are mainly pyrite; the gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu 1.2%, S 2- 4.69%, Fe 6.5%, CaO 8.95%, MgO 6.75%. The original copper sulfide ore is crushed to obtain a particle size of P 80 =3mm sample.

[0118] In this comparative example, a column leaching system is used to simulate heap leaching, and a liquid collecting barrel is used to simulate a qualified liquid pool. After the ore is piled into the leaching column, the leaching column is sealed with a HDPE membrane, and the liquid collecting barrel and the extraction device are sealed with a cover to reduce ammonia volatility, keep the ore pile warm, and control water balance. The ammonia solution is a mixed solution of ammonium bicarbonate and ammonium carbonate, with a pH of 8.5. A high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore throughout the leaching process.

[0119] During the heap leaching process, the reaction temperature was controlled at 30°C by heating the ammonia solution and adding hydrogen peroxide to the ammonia solution to regenerate Cu. 2+ , the redox potential of the leaching solution was regulated to 350 mV (vs. SHE).

[0120] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 84.3% and the ammonia consumption was 19kg / t.

[0121] Comparative Example 6

[0122] The ore sample is a primary copper sulfide ore, with chalcopyrite as the main copper mineral, containing a small amount of bornite and chalcocite; other sulfide minerals are mainly pyrite; the gangue minerals are mainly quartz, chlorite and dolomite. The main chemical composition of the ore is: Cu1.2%, S 2- 4.69%, Fe6.5%, CaO 8.95%, MgO6.75%. The original copper sulfide ore is crushed to obtain a particle size of P 80 =3mm sample.

[0123] In this comparative example, the column leaching system simulates heap leaching, the liquid collecting barrel simulates the qualified liquid pool, and after the ore is piled into the leaching column, it is not sealed, and the liquid collecting barrel and the extraction device are not covered and sealed. The ammonia solution is a mixed solution of ammonium bicarbonate and ammonium carbonate, with a pH of 8.5. During the entire leaching process, a high-concentration ammonia solution with a total ammonia concentration of 2 mol / L is used to drip the ore.

[0124] During the heap leaching process, the reaction temperature was controlled at 30°C by heating the ammonia solution and adding hydrogen peroxide to the ammonia solution to regenerate Cu. 2+ , the redox potential of the leaching solution was regulated to 350 mV (vs. SHE).

[0125] During the leaching process, samples were taken to analyze the copper and ammonia concentrations in the leaching solution. The copper-containing leaching solution was sent to the extraction device for extraction using LIX84-1 extractant, and the raffinate was returned to the leaching process to recycle ammonia. After 150 days of testing, the copper leaching rate was 83.2% and the ammonia consumption was 80kg / t.

[0126] It can be seen from the above embodiments that the ammonia volatilization loss can be controlled by the closed operation of the whole heap leaching-extraction system, and at the same time, the natural rainfall can be isolated from entering the leaching system to avoid the loss of ammonia due to water expansion. Ammonia can be recycled by extracting and returning all the raffinate to the leaching system. By adding a suitable oxidant or bubbling oxygen to regenerate divalent copper, the introduction of non-oxygen gas in the closed system is avoided, and the loss of ammonia escape is reduced. By supplying ammonia in a gradient at different leaching stages, the loss of ammonia entrained in the leaching residue can be reduced.

[0127] For those skilled in the art, various corresponding changes and modifications can be made according to the above technical solutions and concepts, and all of these changes and modifications should be included in the protection scope of the claims of the present invention.

Claims

1. A method for heap leaching of copper sulfide ore with low ammonia consumption, characterized in that: The following steps are involved: S1. Crushing the copper sulfide ore and building a heap on the heap leaching site, then arranging a drip pipe on the heap, and then covering the heap with a sealing film; S2, connecting the dripping pipe to the low concentration ammonia solution container, the medium concentration ammonia solution container and the high concentration ammonia solution container respectively, the low concentration ammonia solution container, the medium concentration ammonia solution container and the high concentration ammonia solution container are in a sealed state, and contain the low concentration ammonia solution, the medium concentration ammonia solution and the high concentration ammonia solution respectively; S3. At different stages of heap leaching, ammonia solutions of different concentrations are dripped onto the ore heap by using a dripping pipe, wherein, at the initial stage of heap leaching, a high-concentration ammonia solution is dripped onto the ore heap, at the middle stage of heap leaching, a medium-concentration ammonia solution is dripped onto the ore heap, and at the final stage of heap leaching, a low-concentration ammonia solution is dripped onto the ore heap; the copper-containing leaching solution flows out into a qualified liquid pool, and the qualified liquid pool is in a sealed state; S4. Pumping the leachate in the qualified liquid pool to an extraction device for extraction, and returning the obtained raffinate to a low-concentration ammonia solution container, a medium-concentration ammonia solution container and / or a high-concentration ammonia solution container for recycling; the mixing and settling tank of the extraction device is in a sealed state.

2. The method according to claim 1, characterized in that During the heap leaching process, the temperature of the ore pile is maintained above 20°C.

3. The method according to claim 1, characterized in that The copper sulfide ore includes any one of primary copper sulfide ore, secondary copper sulfide ore, copper-nickel-cobalt sulfide ore, and oxygen-sulfur mixed ore. The mass content of Cu is 0.1-3%. The particle size of the crushed ore is P 80 =3mm-300mm.

4. The method according to claim 1, characterized in that: In step S4, before the raffinate is returned to the low-concentration ammonia solution container, the medium-concentration ammonia solution container and / or the high-concentration ammonia solution container, the pH value of the raffinate is adjusted to 8.0-10.

5. The method according to claim 4, characterized in that One or more of ammonium sulfate, ammonium carbonate, ammonium bicarbonate and aqueous ammonia is used to adjust the pH of the raffinate.

6. The method according to claim 1, characterized in that In the heap leaching process, the Cu is regenerated by adding an oxidant to the dripping low concentration ammonia solution, medium concentration ammonia solution or high concentration ammonia solution, and / or supplying oxygen to the bottom of the ore heap through an oxygen supply pipe. 2+ , increasing the redox potential of the leaching solution.

7. The method according to claim 6, characterized in that The oxidant is one or more of hydrogen peroxide, sodium peroxide, calcium peroxide, ammonium persulfate, sodium persulfate, and calcium persulfate; and industrial oxygen is used as oxygen supply.

8. The method according to claim 6, characterized in that The redox potential of the leaching solution is controlled by controlling the amount of oxidant added or the amount of oxygen supplied, so that the redox potential of the leaching solution is above 200 mV (vs. SHE).

9. The method according to claim 1, characterized in that: The total ammonia concentration of the high-concentration ammonia solution is 2-3 mol / L, the total ammonia concentration of the medium-concentration ammonia solution is 0.5-2 mol / L, and the total ammonia concentration of the low-concentration ammonia solution is 0-0.5 mol / L.

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