Leaching method of high matte nickel

Abstract

The invention provides a leaching method of high matte nickel. The leaching method comprises the following steps: carrying out normal-pressure leaching on the high-grade matte nickel to obtain ore pulp; the ore pulp and copper salt are mixed, adjusted ore pulp is obtained, and the molar ratio of free copper ions in a liquid phase to nickel in a solid phase is (1.3-3): 1; and under the condition that oxidizing gas is not introduced, the adjusted ore pulp is subjected to pressure leaching, and copper slag and copper-poor leaching liquid are obtained. According to the method, the copper ions in the ore pulp are supplemented, so that the replacement reaction between the copper ions in the liquid phase and the nickel ions in the leaching residues becomes the main reaction for separating nickel and copper, that is, most of the copper ions in the ore pulp liquid phase enter the solid phase of the leaching residues through the reaction, and meanwhile, the nickel ions in the solid phase of the leaching residues enter the liquid phase; the nickel-copper separation effect is achieved, anaerobic pressure leaching can be carried out, the nickel-copper separation effect in the leaching process is improved, the oxygen partial pressure which is difficult to control does not need to be adjusted, and the reaction technology is greatly simplified.

Description

Technical Field

[0001] The present invention relates to the field of hydrometallurgy, and more particularly, to a method for leaching nickel matte. Background Art

[0002] Nickel matte mainly consists of nickel sulfide (Ni3S2) and copper sulfide (CuS), and sometimes also contains other metal sulfides such as iron and cobalt. It is usually black or dark green with different particle sizes. It is a key step product in the process of extracting nickel from laterite ore to pure nickel metal and has important value for subsequent nickel refining. Nickel matte is generally produced by reducing and smelting laterite ore and solidifying at low temperature, and can be further processed by various methods to extract high-purity metallic nickel.

[0003] The existing wet leaching process of nickel matte usually adopts the process of "atmospheric leaching - oxygen pressure leaching - copper slag roasting - electrowinning" (Existing Method 1) or the process of "atmospheric leaching - two-stage oxygen pressure leaching - electrowinning" (Existing Method 2). Atmospheric leaching can adopt one-stage or two-stage atmospheric leaching, and its main purpose is to remove the metal phase in nickel matte. The purpose of the first-stage oxygen pressure leaching in the existing two methods is to make nickel enter the leaching solution and copper enter the slag. In Existing Method 1, the copper slag obtained after one-stage oxygen pressure leaching process is subjected to copper electrowinning after processes such as roasting. In Existing Method 2, the copper slag obtained after one-stage oxygen pressure leaching process is converted into copper sulfate slurry through a two-stage oxygen pressure leaching process, and then through liquid-solid separation, the supernatant enters electrowinning.

[0004] The existing process mainly has four major problems: complex reaction principle, many process control parameters, many problems when dealing with "high copper and low nickel" type nickel matte, and complex oxygen pressure leaching equipment.

[0005] In the first-stage oxygen pressure leaching process of the existing two main methods, it is usually necessary to control appropriate conditions such as oxygen partial pressure and reaction temperature to make nickel enter the liquid phase and copper enter the slag phase, so as to achieve the purpose of nickel-copper separation. The reaction mechanism of this first-stage oxygen pressure leaching is relatively complex, and the main reactions are as follows:

[0006] Displacement reaction 1): CuSO4 + NiS → NiSO4 + Cu 1+x S + NiSO4;

[0007] Displacement reaction 2): CuSO4 + NiS → NiSO4 + Cu 1+x S;

[0008] Oxidation reaction 1): Cu + H2SO4 + O2 → CuSO4 + H2O;

[0009] Oxidation reaction 2): Cu2S + O2 + H2SO4 → CuSO4 + Cu 1+x S + H2O.

[0010] Due to the complexity of the principle of one-stage oxygen pressure leaching, when the existing process treats nickel matte, it is necessary to control many reaction parameters, such as oxygen partial pressure, reaction temperature, copper-nickel ratio, etc., which is rather cumbersome; especially when treating "high copper and low nickel" type nickel matte, there are often problems with poor copper-nickel separation effect. Since the nickel content in the copper slag is relatively high, it cannot be further processed into the subsequent electrowinning process. At the same time, the copper sulfides in the obtained copper slag are diverse and the sulfur content is unstable, bringing uncertainty to the subsequent production. Summary of the Invention

[0011] The main object of the present invention is to provide a method for leaching nickel matte to solve the problem of poor copper-nickel separation effect in the existing nickel matte leaching method.

[0012] To achieve the above object, according to one aspect of the present invention, there is provided a method for leaching nickel matte, the leaching method comprising: Step S1, subjecting nickel matte to atmospheric pressure leaching to obtain a pulp; Step S2, mixing the pulp with a copper salt to obtain an adjusted pulp; in the adjusted pulp, the molar ratio of free copper ions in the liquid phase to nickel in the solid phase is (1.3 - 3):1; Step S3, subjecting the adjusted pulp to pressure leaching without introducing an oxidizing gas to obtain copper slag and a copper-depleted leaching solution.

[0013] Further, the copper content in the nickel matte is 1 - 50 wt%, and the nickel content is 20 - 70 wt%.

[0014] Further, Step S3 includes: subjecting the adjusted pulp to pressure leaching under the condition of 0.05 - 1.00 MPa to obtain copper slag and a copper-depleted leaching solution; preferably, the leaching temperature for pressure leaching is 180 - 220 °C, and the leaching time is 0.5 - 10 h.

[0015] Further, in the adjusted pulp, the content of free copper ions is 500 - 5000 mg / L, and preferably the copper salt is copper sulfate.

[0016] Further, in Step S1, the atmospheric pressure leaching is one-stage atmospheric pressure leaching, including: subjecting nickel matte to atmospheric pressure leaching in an oxidizing gas to obtain a pulp; preferably, the leaching temperature for atmospheric pressure leaching is 50 - 99 °C, the leaching time is 1 - 20 h; preferably, the pH value of the pulp is 1 - 7.

[0017] Further, in step S1, the atmospheric pressure leaching is a two-stage atmospheric pressure leaching, including: step S11, in an oxidizing gas, the first-stage atmospheric pressure leaching of nickel matte is carried out to obtain an intermediate system, and the pH value of the intermediate system is 1-4; step S12, in an oxidizing gas, the second-stage atmospheric pressure leaching of the intermediate system is carried out to obtain a pulp, and the pH value of the pulp is 5-8; preferably, the leaching temperature of the first-stage atmospheric pressure leaching and the second-stage atmospheric pressure leaching are each independently 50-99 °C, and the leaching time are each independently 1-20 h.

[0018] Further, the oxidizing gas is selected from one or more of air, oxygen, and oxygen-rich gas, and the volume content of oxygen in the oxygen-rich gas is 20-90%.

[0019] Further, the leaching method further includes the following steps: step S4, enriching copper in the copper slag to obtain cathode copper.

[0020] Further, step S4 includes: step S41, subjecting the copper slag to fluidized bed roasting and slurry leaching in sequence to obtain a first intermediate product; step S42, subjecting the first intermediate product to copper electrowinning to obtain cathode copper.

[0021] Further, step S4 includes: step S41', subjecting the copper slag to pressure oxygen leaching and liquid-solid separation in sequence to obtain a supernatant as a second intermediate product; step S42', subjecting the second intermediate product to copper electrowinning to obtain cathode copper.

[0022] Applying the technical solution of the present invention, first, through atmospheric leaching treatment, most of the metals in the nickel matte are leached into the liquid phase to obtain a pulp, which includes a liquid phase containing nickel ions and copper ions and a leaching residue containing nickel and copper. Then, before pressure leaching, a copper salt is added to the pulp to make the molar ratio of free copper ions in the liquid phase of the pulp to nickel ions in the leaching residue reach (1.3 - 3):1. By supplementing copper ions in the pulp, the displacement reaction between copper ions in the liquid phase and nickel ions in the leaching residue becomes the main reaction for separating nickel and copper, that is, through the reaction, most of the copper ions in the liquid phase of the pulp enter the solid phase of the leaching residue, and at the same time, nickel ions in the solid phase of the leaching residue enter the liquid phase, achieving the effect of separating nickel and copper. Moreover, in this application, by supplementing copper ions to the pulp and performing anaerobic pressure leaching, only relying on the reaction between copper ions in the liquid phase and nickel ions in the slag, nickel in the slag is leached into the liquid phase, and copper in the liquid phase enters the slag phase. Since there is no oxygen participating in the leaching, the copper in the leaching residue is prevented from being oxidized and leached, improving the separation effect of nickel and copper during the leaching process. Compared with the commonly used pressure oxygen leaching in the prior art, there is no need to adjust the relatively difficult-to-control oxygen partial pressure, greatly simplifying the reaction process. Through the leaching treatment method of this application, the copper grade in the copper-rich slag reaches more than 78% while the nickel grade is lower than 5%, and the copper ion concentration in the copper-poor leaching solution is reduced to below 110 mg / L, achieving the effective separation of nickel and copper. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0024] Figure 1 shows the process flow chart according to Embodiment 1 of the present invention;

[0025] Figure 2 shows the process flow chart according to Embodiment 2 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0027] As described in the background art, there is a problem of poor copper-nickel separation in the leaching method of nickel matte in the prior art. To solve the above problems, the present application provides a leaching method of nickel matte, and the leaching method includes: Step S1, subjecting nickel matte to atmospheric pressure leaching to obtain a pulp; Step S2, mixing the pulp with a copper salt to obtain an adjusted pulp; in the adjusted pulp, the molar ratio of free copper ions in the liquid phase to nickel in the solid phase is (1.3-3):1; Step S3, subjecting the adjusted pulp to pressure leaching without introducing an oxidizing gas to obtain copper slag and copper-depleted leaching solution.

[0028] The leaching method of the present application first performs atmospheric pressure leaching treatment to leach most of the metals in nickel matte into the liquid phase to obtain a pulp, which includes a liquid phase containing nickel ions and copper ions and a leaching residue containing nickel and copper. Then, before pressure leaching, a copper salt is added to the pulp to make the molar ratio of free copper ions in the liquid phase of the pulp to nickel ions in the leaching residue reach (1.3-3):1. By supplementing copper ions in the pulp, the displacement reaction between copper ions in the liquid phase and nickel ions in the leaching residue becomes the main reaction for separating nickel and copper, that is, through the reaction, most of the copper ions in the liquid phase of the pulp enter the solid phase of the leaching residue, and at the same time, nickel ions in the solid phase of the leaching residue enter the liquid phase, achieving the effect of separating nickel and copper. Moreover, the present application supplements copper ions to the pulp and performs anaerobic pressure leaching, and only relies on the reaction between copper ions in the liquid phase and nickel ions in the slag to leach nickel in the slag into the liquid phase, and copper in the liquid phase enters the slag phase. Since there is no oxygen participating in the leaching, the oxidation of copper in the leaching residue and its subsequent leaching are avoided, improving the separation effect of nickel and copper during the leaching process. Compared with the commonly used pressure oxygen leaching in the prior art, there is no need to adjust the relatively difficult-to-control oxygen partial pressure, greatly simplifying the reaction process. Through the leaching treatment method of the present application, the copper grade in the copper-rich slag reaches more than 78% and the nickel grade is lower than 5%, and the copper ion concentration in the copper-depleted leaching solution is reduced to less than 110 mg / L, achieving the effect of effectively separating nickel and copper.

[0029] In a preferred embodiment, the copper content in nickel matte is 1-50 wt%, and the nickel content is 20-70 wt%. The leaching method of the present application is applicable to various types of nickel matte (as well as low-grade nickel matte), and all have very good leaching effects. Among them, the treatment effect on "high copper and low nickel type" nickel matte is the best. After atmospheric pressure leaching of "high copper and low nickel type" nickel matte, the nickel content in the leaching residue is further reduced, and it is not easy to undergo a displacement reaction and thus difficult to be further leached. The present application supplements copper ions to the pulp to improve the displacement ability of copper and nickel, so that the relatively difficult-to-react nickel in the leaching residue is displaced, effectively achieving the effect of separating copper and nickel in nickel matte. And because the copper content in the above nickel matte is relatively large, less copper needs to be supplemented, achieving a good nickel-copper separation effect at a relatively low leaching cost.

[0030] As described above, since copper ions are supplemented in the pulp, the present invention can perform anaerobic pressure leaching on the pulp. In a preferred embodiment, step S3 includes: performing pressure leaching on the adjusted pulp under the condition of 0.05 - 1.00 MPa to obtain copper slag and copper-depleted leachate; preferably, the leaching temperature for the pressure leaching is 180 - 220 °C, and the leaching time is 0.5 - 10 h. Within the above leaching process parameters, the separation effect of copper and nickel in the anaerobic pressure leaching can be further improved.

[0031] In order to further improve the nickel-copper separation effect of the leaching method of the present application, in a preferred embodiment, in the adjusted pulp, the content of free copper ions is 500 - 5000 mg / L. The copper salt of the present application can be selected from common copper salts in the art. In order to introduce as few impurity ions as possible into the reaction system, copper sulfate is preferably used as the copper salt.

[0032] In order to better cooperate with the subsequent pressure leaching treatment, the atmospheric pressure leaching can be single-stage atmospheric pressure leaching or two-stage atmospheric pressure leaching, and sulfuric acid leaching can be used. In a preferred embodiment, in step S1, the atmospheric pressure leaching is single-stage atmospheric pressure leaching, including: performing atmospheric pressure leaching on nickel matte in an oxidizing gas to obtain pulp; preferably, the leaching temperature for the atmospheric pressure leaching is 50 - 99 °C, and the leaching time is 1 - 20 h; preferably, the pH value of the pulp is 1 - 7. By reacting nickel matte with an acid, metals such as copper and nickel in the nickel matte enter the liquid phase, so as to further ensure the effect of the above single-stage acid leaching and further improve the selective leaching effect of metals. The purpose of introducing the oxidizing gas is to oxidize nickel and copper in the metallic state and sulfide state and promote the leaching of copper and nickel.

[0033] In a preferred embodiment, in step S1, the atmospheric pressure leaching is two-stage atmospheric pressure leaching, including: step S11, performing the first-stage atmospheric pressure leaching on nickel matte in an oxidizing gas to obtain an intermediate system, and the pH value of the intermediate system is 1 - 4; step S12, performing the second-stage atmospheric pressure leaching on the intermediate system in an oxidizing gas to obtain pulp, and the pH value of the pulp is 5 - 8; preferably, the leaching temperatures for the first-stage atmospheric pressure leaching and the second-stage atmospheric pressure leaching are independently 50 - 99 °C, and the leaching times are independently 1 - 20 h. Through two-stage acid leaching, the selective leaching of metals in nickel matte can be promoted, and the subsequent pressure leaching can have a better effect. Liquid-solid separation is required between the first-stage acid leaching and the second-stage acid leaching. Although the temperatures and times of the two stages are similar, the final pH values of the two stages are different, so as to effectively remove the nickel-copper metal phase, and at the same time, the pH of the solution after the second-stage leaching is maintained around neutral, reducing the consumption of alkali for neutralizing the acid. By further limiting the reaction time and temperature, the effect of the above two-stage atmospheric pressure leaching can be further improved.

[0034] For the purpose of further oxidizing nickel and copper in the metallic and sulfide states and promoting the leaching of copper and nickel, in a preferred embodiment, the oxidizing gas is selected from one or more of air, oxygen, and oxygen-enriched gas, and the volume content of oxygen in the oxygen-enriched gas is 20-90%.

[0035] Since the content of copper in the copper slag obtained by the leaching method of this application is relatively high and the content of nickel is relatively low, copper can be effectively enriched from the copper slag to obtain copper products. In a preferred embodiment, the leaching method further includes the following steps: Step S4, enriching copper in the copper slag to obtain cathode copper. The method for enriching copper in this application can be selected by those skilled in the art with reference to the prior art. In order to further improve the enrichment effect of copper in the copper slag obtained by the leaching method of this application, the "roasting-electrowinning method" or the "pressure oxygen leaching-electrowinning method" is preferably used.

[0036] In a preferred embodiment, Step S4 includes: Step S41, subjecting the copper slag to fluidized roasting and slurry leaching in sequence to obtain a first intermediate product; Step S42, performing copper electrowinning on the first intermediate product to obtain cathode copper. For example, sulfuric acid roasting of copper-rich slag, sulfuric acid leaching of roasted slag, and electrowinning of the leaching solution (copper sulfate solution) to obtain cathode copper after electrowinning.

[0037] In a preferred embodiment, Step S4 includes: Step S41', subjecting the copper slag to pressure oxygen leaching and liquid-solid separation in sequence to obtain the supernatant as the second intermediate product; Step S42', performing copper electrowinning on the second intermediate product to obtain cathode copper. For example, pressure leaching of copper-rich slag to obtain copper sulfate solution, and electrowinning the supernatant after liquid-solid separation, which is the copper sulfate solution, to obtain copper.

[0038] The grade of copper in the electrode copper obtained by the above method is relatively high and can be applied to various fields such as electrical appliances, light industry, and machinery manufacturing.

[0039] The following further describes this application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by this application.

[0040] Example 1

[0041] The leaching process flow chart of nickel matte is shown in Figure 1 .

[0042] A method for leaching nickel matte, the content of copper in the nickel matte is 41.02 wt%, the content of nickel is 31.25 wt%, and the leaching method includes:

[0043] Step S1, atmospheric leaching

[0044] Step S11: In an oxidizing gas (air), carry out the first-stage atmospheric leaching of nickel matte (sulfuric acid leaching, leaching temperature is 65°C, leaching time is 6.5 h) to obtain an intermediate system (pH value is 1.5).

[0045] Step S12: In an oxidizing gas (air), carry out the second-stage atmospheric leaching of the intermediate system (sulfuric acid leaching, leaching temperature is 85°C, leaching time is 5 h) to obtain pulp (pH value is 6.2).

[0046] The content of Cu in the obtained leaching residue is 45.05%, and the content of Ni is 20.96%; the concentration of the leaching solution is 13498 mg / L.

[0047] Step S2, copper supplementation to obtain adjusted pulp

[0048] Mix the pulp and copper sulfate to obtain adjusted pulp; in the adjusted pulp, the molar ratio of free copper ions in the liquid phase to nickel in the solid phase is 2:1, and the content of free copper ions is 3000 mg / L.

[0049] Step S3, pressure leaching

[0050] Under the condition of not introducing an oxidizing gas and at 0.5 MPa, carry out pressure leaching on the adjusted pulp (leaching temperature is 190°C, leaching time is 5 h) to obtain copper slag and copper-poor leaching solution. Among them, the filtrate of the pressure leaching can be returned to the atmospheric leaching for further metal recovery. The concentration of Cu ions in the copper-poor leaching solution is 44.13 mg / L, and the concentration of Ni ions is 10640 mg / L; the content of Cu in the copper slag is 70.64%, and the content of Ni is 3.66%.

[0051] Step S4, copper enrichment

[0052] Step S41: Carry out fluidized bed roasting and slurry leaching on the copper slag in sequence to obtain a first intermediate product.

[0053] Step S42: Carry out copper electrowinning on the first intermediate product to obtain cathode copper.

[0054] It can be seen that in this embodiment, after pressure leaching, the concentration of Ni ions in the leaching solution is relatively high, and the concentration of Cu ions is relatively low; the copper grade in the leaching residue is relatively high, while the nickel grade is relatively low; thus, the effect of "copper-nickel separation" where copper enters the slag and nickel mainly enters the liquid can be achieved, and at the same time, the enrichment of nickel and copper can be realized.

[0055] Example 2

[0056] The difference from Example 1 is that the process flow chart of the leaching of nickel matte is shown in Figure 2 .

[0057] Step S4, copper enrichment

[0058] Step S41', subject the copper slag to pressure oxidative leaching and liquid-solid separation in sequence to obtain a supernatant as the second intermediate product;

[0059] Step S42', perform copper electrowinning on the second intermediate product to obtain cathode copper.

[0060] Example 3

[0061] Step S1, atmospheric leaching

[0062] Step S11, subject the nickel matte to the first-stage atmospheric leaching (sulfuric acid leaching, leaching temperature is 50 °C, leaching time is 20 h) in an oxidizing gas (oxygen-enriched gas, volume content of oxygen is 20%) to obtain an intermediate system (pH value is 1);

[0063] Step S12, subject the intermediate system to the second-stage atmospheric leaching (sulfuric acid leaching, leaching temperature is 50 °C, leaching time is 20 h) in an oxidizing gas (oxygen-enriched gas, volume content of oxygen is 20%) to obtain a pulp (pH value is 5);

[0064] Step S2, copper supplementation to obtain adjusted pulp

[0065] Mix the pulp and copper sulfate to obtain an adjusted pulp; in the adjusted pulp, the molar ratio of free copper ions in the liquid phase to nickel in the solid phase is 1.3:1, and the content of free copper ions is 500 mg / L;

[0066] Step S3, pressure leaching

[0067] Subject the adjusted pulp to pressure leaching (leaching temperature is 180 °C, leaching time is 10 h) without introducing an oxidizing gas and at 0.05 MPa to obtain copper slag and copper-depleted leaching solution.

[0068] Step S4, copper enrichment

[0069] Step S41, subject the copper slag to fluidized bed roasting and pulping leaching in sequence to obtain a first intermediate product;

[0070] Step S42, perform copper electrowinning on the first intermediate product to obtain cathode copper.

[0071] Example 4

[0072] Step S1, atmospheric leaching

[0073] Step S11, subject the nickel matte to the first-stage atmospheric leaching (sulfuric acid leaching, leaching temperature is 99 °C, leaching time is 1 h) in an oxidizing gas (oxygen-enriched gas, volume content of oxygen is 90%) to obtain an intermediate system (pH value is 4);

[0074] In step S12, in an oxidizing gas (oxygen-enriched gas with an oxygen volume content of 90%), the intermediate system is subjected to a second-stage atmospheric leaching (sulfuric acid leaching, leaching temperature is 99 °C, leaching time is 1 h) to obtain a pulp (pH value is 8).

[0075] Step S2, copper supplementation to obtain adjusted pulp

[0076] The pulp and copper sulfate are mixed to obtain an adjusted pulp; in the adjusted pulp, the molar ratio of free copper ions in the liquid phase to nickel in the solid phase is 3:1, and the content of free copper ions is 5000 mg / L.

[0077] Step S3, pressure leaching

[0078] Under the condition of not introducing an oxidizing gas and at 1.00 MPa, the adjusted pulp is subjected to pressure leaching (leaching temperature is 220 °C, leaching time is 0.5 h) to obtain copper slag and copper-depleted leaching solution.

[0079] Step S4, copper enrichment

[0080] In step S41, the copper slag is successively subjected to fluidized bed roasting and slurry leaching to obtain a first intermediate product.

[0081] In step S42, the first intermediate product is subjected to copper electrowinning to obtain cathode copper.

[0082] Example 5

[0083] The difference from Example 1 is that

[0084] Step S1, atmospheric leaching

[0085] In an oxidizing gas (air), matte is subjected to atmospheric leaching (sulfuric acid leaching, leaching temperature is 50 °C, leaching time is 20 h) to obtain a pulp (pH value is 1).

[0086] Example 6

[0087] The difference from Example 1 is that

[0088] Step S1, atmospheric leaching

[0089] In an oxidizing gas (air), matte is subjected to atmospheric leaching (sulfuric acid leaching, leaching temperature is 99 °C, leaching time is 1 h) to obtain a pulp (pH value is 7).

[0090] Comparative Example 1

[0091] A method for leaching matte, where the copper content in the matte is 41.02 wt%, and the nickel content is 31.25 wt%. The leaching method includes:

[0092] Step S1, atmospheric leaching

[0093] Step S11: In an oxidizing gas (air), perform atmospheric leaching on matte nickel in the first stage (sulfuric acid leaching, leaching temperature is 65 °C, leaching time is 6.5 h) to obtain an intermediate system (pH value is 1.5).

[0094] Step S12: In an oxidizing gas (air), perform atmospheric leaching on the intermediate system in the second stage (sulfuric acid leaching, leaching temperature is 85 °C, leaching time is 5 h) to obtain pulp (pH value is 6.2).

[0095] The content of Cu in the obtained leaching residue is 45.05%, and the content of Ni is 20.96%; the concentration of the leaching solution is 13498 mg / L.

[0096] Step S2, pressure leaching

[0097] Under the condition of introducing an oxidizing gas (air) and 0.5 MPa, perform pressure leaching on the adjusted pulp (leaching temperature is 190 °C, leaching time is 5 h) to obtain copper slag and copper - poor leaching solution. The concentration of Cu ions in the copper - poor leaching solution is 44.13 mg / L, and the concentration of Ni ions is 10640 mg / L; the content of Cu in the copper slag is 70.64%, and the content of Ni is 3.66%.

[0098] Step S3, copper enrichment

[0099] Step S31: Conduct flash roasting and slurry leaching on the copper slag in sequence to obtain a first intermediate product;

[0100] Step S32: Perform copper electrowinning on the first intermediate product to obtain cathode copper, and return the electrolyte to the pressure leaching step.

[0101] The contents of copper and nickel in the copper slag and copper - poor leaching solution after pressure leaching in the above - mentioned examples and comparative examples are shown in Table 1.

[0102] Table 1

[0103]

[0104] From the above description, it can be seen that compared with the comparative example, the above embodiments of the present invention achieve the following technical effects: By supplementing copper ions in the pulp, the displacement reaction between copper ions in the liquid phase and nickel ions in the leaching residue becomes the main reaction for separating nickel and copper, that is, through the reaction, most of the copper ions in the pulp liquid phase enter the leaching residue solid phase, and at the same time, the nickel ions in the leaching residue solid phase enter the liquid phase, achieving the effect of separating nickel and copper. Moreover, oxygen-free pressure leaching can be carried out, improving the separation effect of nickel and copper during the leaching process, without the need to adjust the relatively difficult-to-control oxygen partial pressure, greatly simplifying the reaction process.

[0105] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for leaching nickel matte, characterized in that, The leaching method includes: Step S1, subjecting nickel matte to atmospheric pressure leaching to obtain a pulp; Step S2, mixing the pulp with a copper salt to obtain an adjusted pulp; in the adjusted pulp, the molar ratio of free copper ions in the liquid phase to nickel in the solid phase is (1.3 - 3):1; Step S3, subjecting the adjusted pulp to pressure leaching without introducing an oxidizing gas to obtain copper slag and copper-poor leachate.

2. The leaching method according to claim 1, wherein The nickel matte contains 1 - 50 wt% of copper and 20 - 70 wt% of nickel.

3. The leaching method according to claim 1 or 2, characterized in that, The step S3 includes: Subjecting the adjusted pulp to the pressure leaching under the condition of 0.05 - 1.00 MPa to obtain the copper slag and the copper-poor leachate; Preferably, the leaching temperature of the pressure leaching is 180 - 220 °C, and the leaching time is 0.5 - 10 h.

4. The leaching method according to any one of claims 1 to 3, characterized in that In the adjusted pulp, the content of the free copper ions is 500 - 5000 mg / L, and preferably the copper salt is copper sulfate.

5. The leaching method according to any one of claims 1 to 4, characterized in that, In the step S1, the atmospheric pressure leaching is single-stage atmospheric pressure leaching, including: Subjecting the nickel matte to atmospheric pressure leaching in an oxidizing gas to obtain the pulp; Preferably, the leaching temperature of the atmospheric pressure leaching is 50 - 99 °C, and the leaching time is 1 - 20 h; Preferably, the pH value of the pulp is 1 - 7.

6. The leaching method according to any one of claims 1 to 5, characterized in that, In the step S1, the atmospheric pressure leaching is two-stage atmospheric pressure leaching, including: Step S11, subjecting the nickel matte to the first-stage atmospheric pressure leaching in an oxidizing gas to obtain an intermediate system, and the pH value of the intermediate system is 1 - 4; Step S12, subjecting the intermediate system to the second-stage atmospheric pressure leaching in an oxidizing gas to obtain the pulp, and the pH value of the pulp is 5 - 8; Preferably, the leaching temperatures of the first-stage atmospheric pressure leaching and the second-stage atmospheric pressure leaching are each independently 50 - 99 °C, and the leaching times are each independently 1 - 20 h.

7. The leaching method according to claim 5 or 6, characterized in that, The oxidizing gas is selected from one or more of air, oxygen, and oxygen-rich gas, and the volume content of oxygen in the oxygen-rich gas is 20 - 90%.

8. The leaching method according to any one of claims 1 to 7, characterized in that, The leaching method further includes the following step: Step S4, enriching copper in the copper slag to obtain cathode copper.

9. The leaching method according to claim 8, characterized in that, The step S4 includes: Step S41, subjecting the copper slag to fluidized bed roasting and slurry leaching in sequence to obtain a first intermediate product; Step S42, subjecting the first intermediate product to copper electrowinning to obtain cathode copper.

10. The leaching method according to claim 8, characterized in that, The step S4 includes: Step S41', subjecting the copper slag to pressure oxygen leaching and liquid-solid separation in sequence to obtain a supernatant as a second intermediate product; Step S42', subjecting the second intermediate product to copper electrowinning to obtain cathode copper.

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