Method for selectively leaching valuable metal element enriched copper in copper-cadmium slag through waste electrolyte

Abstract

The invention relates to the technical field of non-ferrous metal recovery, and discloses a method for selectively leaching valuable metal element enriched copper in copper-cadmium slag through waste electrolyte. The invention relates to a method for selectively leaching valuable metal element enriched copper in copper-cadmium slag by using waste electrolyte, which comprises the following steps: 1) placing the copper-cadmium slag in a leaching solution, precipitating and filtering to obtain precipitated slag and a solution after copper precipitation; and (2) the precipitation residues obtained in the step (1) are placed in waste electrolyte to be leached and filtered, and leaching liquid and enriched residues are obtained. According to the method for selectively leaching the valuable metal element enriched copper in the copper-cadmium slag through the waste electrolyte, the waste electrolyte serves as a leaching agent, efficient leaching of cobalt and precipitation and enrichment of copper are achieved through precipitation, efficient leaching of zinc and cadmium is achieved through leaching, the acidity of the solution is regulated and controlled in stages by monitoring the pH, copper is precisely recycled, and the method is suitable for industrial production. The copper loss rate is reduced to 0.1 mg / L or below, and the economic value of the copper-cadmium slag is improved.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metal recovery, and in particular to a method for enriching copper by selectively leaching valuable metal elements in copper-cadmium slag with waste electrolyte. Background Art

[0002] In the hydrometallurgical zinc smelting process, the formation of copper-cadmium slag is the result of multiple reactions during the smelting and purification process. First, the zinc sulfide in the zinc concentrate is roasted to form roasted sand. Thereafter, the roasted sand is subjected to a neutral leaching process to produce a metal-rich supernatant. This process not only dissolves the main metal zinc, but also inevitably brings some impurity metals such as copper, cadmium, and cobalt into the solution. If these impurities are not removed, they will seriously affect the subsequent zinc electrolytic extraction efficiency and the quality of the final product.

[0003] In order to solve the impurity problem, a liquid purification process is introduced in the production process. During this stage, zinc powder is added for replacement reaction. The addition of zinc powder causes metal impurities such as copper and cadmium to precipitate through replacement reaction, thereby separating them from the solution. This method not only effectively removes impurities that are unfavorable to zinc electrolysis, but also precipitates impurities in the form of solid phase to form copper-cadmium slag. The products of the liquid purification process mainly include copper-cadmium slag and cobalt slag. The copper-cadmium slag contains not only replaced copper and cadmium, but also some unreacted excess zinc powder. At the same time, in the replacement process of removing copper and cadmium, some cobalt will also be replaced. Therefore, copper-cadmium slag is often rich in four commercially valuable metals, namely copper, zinc, cadmium and cobalt. The presence of these metals gives copper-cadmium slag a higher resource utilization value. Through appropriate subsequent treatment, these valuable metals can be recovered to deepen the efficiency of resource utilization.

[0004] As global zinc production increases year by year, the amount of copper-cadmium slag produced in the zinc smelting and purification process has increased significantly. Copper-cadmium slag is rich in valuable metals such as zinc, cadmium, cobalt and copper. Traditional treatment methods include acid leaching-replacement method, roasting-leaching method, etc., but there are problems such as low metal recovery rate, complex process flow, and high waste liquid treatment cost. For example, the conventional acid leaching method consumes a large amount of fresh sulfuric acid, and copper is easily dissolved with zinc and cadmium, resulting in subsequent separation difficulties; the replacement method requires the use of zinc powder, which is costly and produces secondary waste slag. In addition, the treatment pressure of zinc smelting waste electrolyte (containing sulfuric acid and metals such as zinc and cadmium) is increasing, and there is an urgent need for a green and efficient method to achieve the synergistic resource utilization of copper-cadmium slag and waste electrolyte. Summary of the invention

[0005] The purpose of the present invention is to provide a method for enriching copper by selectively leaching valuable metal elements in copper-cadmium slag with waste electrolyte.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for selectively leaching valuable metal elements in copper-cadmium slag with waste electrolyte to enrich copper, comprising the following steps:

[0008] 1) Precipitation: Place the copper-cadmium slag in the leaching solution, precipitate, and filter to obtain the precipitated slag and the copper-precipitated solution;

[0009] 2) Leaching: Place the precipitated slag obtained in step 1) in the waste electrolyte, leach, and filter to obtain the leaching solution and the enriched slag;

[0010] Among them, the leaching solution described in step 1) is the leaching solution obtained in step 2).

[0011] Further, in step 1), before placing the copper-cadmium slag in the leaching solution, the sulfuric acid concentration in the leaching solution needs to be adjusted to 60-80 g / L.

[0012] Further, in step 1), the solid-liquid ratio of the copper-cadmium slag to the leaching solution is 1 g:(2.5-5) mL.

[0013] Further, in step 1), the temperature of the precipitation is 30-40 °C, and the time is 80-150 min.

[0014] Further, in step 1), the end point pH of the precipitation needs to be controlled at 4.7-5.5.

[0015] Further, in step 2), before placing the precipitated slag obtained in step 1) in the waste electrolyte, the sulfuric acid concentration in the waste electrolyte needs to be adjusted to 100-150 g / L.

[0016] Further, in step 2), the solid-liquid ratio of the precipitated slag to the waste electrolyte is 1 g:(3-6) mL.

[0017] Further, in step 2), the temperature of the leaching is 35-50 °C, and the time is 180-300 min.

[0018] Further, in step 2), the end point pH of the leaching needs to be controlled at 2.0-3.0.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] The method for selectively leaching valuable metal elements in copper-cadmium slag with waste electrolyte to enrich copper according to the present invention uses waste electrolyte as the leaching agent, realizes the efficient leaching of cobalt and the precipitation and enrichment of copper through precipitation, realizes the efficient leaching of zinc and cadmium through leaching, and precisely recovers copper by monitoring the pH and regulating the solution acidity in stages, reducing the copper loss rate to less than 0.1 mg / L, and improving the economic value of copper-cadmium slag;

[0021] The method of the present invention for selectively leaching valuable metal elements in copper-cadmium slag with waste electrolyte to enrich copper replaces fresh sulfuric acid with waste electrolyte, reduces raw material costs and alleviates the pressure of waste liquid treatment;

[0022] The method of the present invention for selectively leaching valuable metal elements in copper-cadmium slag with waste electrolyte is environmentally friendly and economically effective, is used for treating purification slag generated in the zinc smelting industry, realizes the comprehensive utilization of resources and the sustainable development of the environment, and is expected to provide a new solution for the treatment of purification slag and resource recovery in the zinc smelting industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0024] Figure 1 is the process flow chart of the present invention;

[0025] Figure 2 is the on-line pH diagram of the precipitation process of the present invention;

[0026] Figure 3 is the potential-pH diagram of the main components of the leaching solution. DETAILED DESCRIPTION OF THE INVENTION

[0027] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and implementation schemes of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0028] In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0029] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes the preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0030] Without departing from the scope or spirit of the present invention, various modifications and variations can be made to the specific embodiments of the description of the present invention, which are obvious to those skilled in the art. Other embodiments obtained from the description of the present invention are obvious to those skilled in the art. The description and examples of the present invention are merely exemplary.

[0031] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0032] In the following examples, the copper-cadmium slag is from a certain factory, and its chemical composition is shown in Table 1;

[0033] Table 1 Chemical Composition

[0034]

[0035] In the following examples, the waste electrolyte is from a certain factory, and its chemical composition is shown in Table 2;

[0036] Table 2 Chemical Composition

[0037]

[0038] In the following examples, a method for selectively leaching valuable metal elements in copper-cadmium slag with waste electrolyte to enrich copper includes the following steps:

[0039] 1) Precipitation: Adjust the sulfuric acid concentration in the leaching solution to 60 - 80 g / L, then place the copper-cadmium slag in the leaching solution according to the solid-liquid ratio of copper-cadmium slag to leaching solution of 1 g∶(2.5 - 5) mL, control the end point pH to be 4.7 - 5.5, precipitate at 30 - 40 °C for 80 - 150 min, filter to obtain precipitate slag and copper-precipitated solution;

[0040] 2) Leaching: Adjust the sulfuric acid concentration in the waste electrolyte to 100 - 150 g / L, then place the precipitate slag obtained in step 1) in the waste electrolyte according to the solid-liquid ratio of precipitate slag to waste electrolyte of 1 g∶(3 - 6) mL, control the end point pH to be 2.0 - 3.0, leach at 35 - 50 °C for 180 - 300 min, filter to obtain leaching solution and enriched slag;

[0041] Among them, the leaching solution described in step 1) is the leaching solution obtained in step 2).

[0042] Example 1

[0043] A method for selectively leaching valuable metal elements in copper-cadmium slag with waste electrolyte to enrich copper

[0044] 1) Precipitation: Adjust the sulfuric acid concentration in the leaching solution to 70 g / L. Then, according to the solid-liquid ratio of copper-cadmium slag to leaching solution of 1 g∶3.5 mL, place the copper-cadmium slag in the leaching solution, control the final pH to be 5.2 - 5.5, precipitate at 35 °C for 120 min, filter to obtain the precipitated slag and the solution after copper precipitation;

[0045] 2) Leaching: Adjust the sulfuric acid concentration in the waste electrolyte to 125 g / L. Then, according to the solid-liquid ratio of the precipitated slag to the waste electrolyte of 1 g∶3.5 mL, place the precipitated slag obtained in step 1) in the waste electrolyte, control the final pH to be 2.0 - 2.5, leach at 45 °C for 240 min, filter to obtain the leaching solution and the enriched slag;

[0046] Among them, the leaching solution mentioned in step 1) is the leaching solution obtained in step 2).

[0047] Detect the contents of zinc, cadmium, cobalt, and copper in the enriched slag obtained in step 2), and calculate the leaching rates of zinc, cadmium, and cobalt; the detection and calculation results are shown in Table 3;

[0048] Table 3 Detection and calculation results

[0049]

[0050] Detect the copper residue content in the leaching solution obtained in step 2). After detection, the copper residue content in the leaching solution is 0.01 mg / L.

[0051] Example 2

[0052] A method for selectively leaching valuable metal elements in copper-cadmium slag from waste electrolyte to enrich copper

[0053] 1) Precipitation: Adjust the sulfuric acid concentration in the leaching solution to 80 g / L. Then, according to the solid-liquid ratio of copper-cadmium slag to leaching solution of 1 g∶2.5 mL, place the copper-cadmium slag in the leaching solution, control the final pH to be 4.7 - 5.2, precipitate at 35 °C for 120 min, filter to obtain the precipitated slag and the solution after copper precipitation;

[0054] 2) Leaching: Adjust the sulfuric acid concentration in the waste electrolyte to 125 g / L. Then, according to the solid-liquid ratio of the precipitated slag to the waste electrolyte of 1 g∶3.5 mL, place the precipitated slag obtained in step 1) in the waste electrolyte, control the final pH to be 2.5 - 3.0, leach at 45 °C for 240 min, filter to obtain the leaching solution and the enriched slag;

[0055] Among them, the leaching solution mentioned in step 1) is the leaching solution obtained in step 2).

[0056] Detect the contents of zinc, cadmium, cobalt, and copper in the enriched slag obtained in step 2), and calculate the leaching rates of zinc, cadmium, and cobalt; the detection and calculation results are shown in Table 4;

[0057] Table 4 Detection and calculation results

[0058]

[0059] The copper residue in the leaching solution obtained in step 2) was detected. After detection, the copper residue in the leaching solution was 0.5 mg / L.

[0060] Example 3

[0061] A method for selectively leaching valuable metal elements in copper-cadmium slag from waste electrolyte to enrich copper

[0062] 1) Precipitation: Adjust the sulfuric acid concentration in the leaching solution to 80 g / L. Then, according to the solid-liquid ratio of copper-cadmium slag to leaching solution of 1 g∶3.5 mL, place the copper-cadmium slag in the leaching solution, control the end-point pH to be 4.7 - 5.3, precipitate at 35 °C for 150 min, filter to obtain precipitate residue and copper-precipitated solution;

[0063] 2) Leaching: Adjust the sulfuric acid concentration in the waste electrolyte to 150 g / L. Then, according to the solid-liquid ratio of precipitate residue to waste electrolyte of 1 g∶3.5 mL, place the precipitate residue obtained in step 1) in the waste electrolyte, control the end-point pH to be 2.0 - 2.5, leach at 45 °C for 240 min, filter to obtain leaching solution and enriched residue;

[0064] Among them, the leaching solution described in step 1) is the leaching solution obtained in step 2).

[0065] The zinc, cadmium, cobalt, and copper contents in the enriched residue obtained in step 2) were detected, and the leaching rates of zinc, cadmium, and cobalt were calculated; the detection and calculation results are shown in Table 5;

[0066] Table 5 Detection and calculation results

[0067]

[0068] The copper residue in the leaching solution obtained in step 2) was detected. After detection, the copper residue in the leaching solution was 2.2 mg / L.

[0069] Example 4

[0070] A method for selectively leaching valuable metal elements in copper-cadmium slag from waste electrolyte to enrich copper

[0071] 1) Precipitation: Adjust the sulfuric acid concentration in the leaching solution to 80 g / L. Then, according to the solid-liquid ratio of copper-cadmium slag to leaching solution of 1 g∶3.5 mL, place the copper-cadmium slag in the leaching solution, control the end-point pH to be 4.7 - 5.0, precipitate at 35 °C for 120 min, filter to obtain precipitate residue and copper-precipitated solution;

[0072] 2) Leaching: Adjust the sulfuric acid concentration in the waste electrolyte to 150 g / L. Then, according to the solid-liquid ratio of the precipitate residue to the waste electrolyte being 1 g∶3.5 mL, place the precipitate residue obtained in step 1) into the waste electrolyte, control the final pH to be 2.5 - 3.0, leach at 45°C for 240 min, and filter to obtain a leachate and an enriched residue;

[0073] Among them, the leachate described in step 1) is the leachate obtained in step 2).

[0074] Detect the contents of zinc, cadmium, cobalt, and copper in the enriched residue obtained in step 2), and calculate the leaching rates of zinc, cadmium, and cobalt; the detection and calculation results are shown in Table 6;

[0075] Table 6 Detection and Calculation Results

[0076]

[0077] Detect the copper residue content in the leachate obtained in step 2). After detection, the copper residue content in the leachate is 8 mg / L.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the specific implementation manners of the present invention or make equivalent replacements. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A method for selectively leaching valuable metal elements in copper-cadmium slag from waste electrolyte to enrich copper, characterized in that, It includes the following steps: 1) Precipitation: Place the copper-cadmium residue in the leaching solution, conduct precipitation, and filter to obtain the precipitated residue and the post-copper-precipitation solution; 2) Leaching: Place the precipitated residue obtained in step 1) in the spent electrolyte, conduct leaching, and filter to obtain the leaching solution and the enriched residue; Among them, the leaching solution described in step 1) is the leaching solution obtained in step 2).

2. The method for enriching copper by selectively leaching valuable metal elements in copper-cadmium slag from waste electrolyte according to claim 1, characterized in that, In step 1), before placing the copper-cadmium residue in the leaching solution, the sulfuric acid concentration in the leaching solution needs to be adjusted to 60 - 80 g / L.

3. The method for enriching copper by selectively leaching valuable metal elements in copper-cadmium slag from waste electrolyte according to claim 1, characterized in that, In step 1), the solid-liquid ratio of the copper-cadmium residue to the leaching solution is 1 g∶(2.5 - 5) mL.

4. A method for enriching copper by selectively leaching valuable metal elements in copper-cadmium slag from waste electrolyte according to claim 1, characterized in that, In step 1), the temperature of the precipitation is 30 - 40 °C, and the time is 80 - 150 min.

5. A method for enriching copper by selectively leaching valuable metal elements in copper-cadmium slag from waste electrolyte according to claim 1, characterized in that, In step 1), the end-point pH of the precipitation needs to be controlled at 4.7 - 5.

5.

6. A method for enriching copper by selectively leaching valuable metal elements in copper-cadmium slag from waste electrolyte according to claim 1, characterized in that, In step 2), before placing the precipitated residue obtained in step 1) in the spent electrolyte, the sulfuric acid concentration in the spent electrolyte needs to be adjusted to 100 - 150 g / L.

7. A method for enriching copper by selectively leaching valuable metal elements in copper-cadmium slag from waste electrolyte according to claim 1, characterized in that, In step 2), the solid-liquid ratio of the precipitated residue to the spent electrolyte is 1 g∶(3 - 6) mL.

8. A method for enriching copper by selectively leaching valuable metal elements in copper-cadmium slag from waste electrolyte according to claim 1, characterized in that, In step 2), the temperature of the leaching is 35 - 50 °C, and the time is 180 - 300 min.

9. A method for enriching copper by selectively leaching valuable metal elements in copper-cadmium slag from waste electrolyte according to claim 1, characterized in that, In step 2), the end-point pH of the leaching needs to be controlled at 2.0 - 3.0.

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