Method for recovering copper from converter slag and use

Abstract

This invention belongs to the field of copper recovery technology, and specifically relates to a method and application for recovering copper from converter slag. A method for recovering copper from converter slag includes the following steps: (1) preparation of leaching solution; (2) adding converter slag to the leaching solution, leaching to obtain a first leaching solution and a first leaching residue; (3) adding the first leaching solution to the cathode chamber of an electrodeposition device, electrodeposition, and filtration to obtain a first electrodeposition post-solution and a first electrodeposition copper powder; (4) using the first leaching residue as raw material and the first electrodeposition post-solution as leaching solution, repeating step (2) to obtain a second leaching solution and a second leaching residue; (5) using the second leaching solution as electrodeposition solution, repeating step (3) to obtain a second electrodeposition post-solution and a second electrodeposition copper powder; (6) adding acid to the second electrodeposition post-solution obtained in step (5), precipitating, filtering, and completing the recovery of the complexing agent. This invention recovers copper from converter slag with a high copper recovery rate, which can improve resource utilization and economic benefits, reduce pollution emissions, and is environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of copper recovery technology, and specifically relates to a method and application for recovering copper from converter slag. Background Technology

[0002] In pyrometallurgical copper smelting, converter slag is a major byproduct. Its copper content is low, making efficient separation and recovery difficult, resulting in low secondary resource utilization. Currently, metal recovery processes from converter slag mainly fall into three categories: slag beneficiation, carbothermal reduction, and hydrometallurgical leaching. Hydrometallurgical leaching offers greater selectivity for specific metals; by selecting an appropriate leaching system based on the physicochemical properties of the target metal, efficient selective leaching can be achieved. For copper recovery, sulfuric acid or hydrochloric acid leaching, or ammonia-based complexation leaching, are commonly used. However, acid leaching consumes large amounts of acid and has weak selectivity; ammonia leaching offers strong selectivity but generates irritating gases, making waste gas absorption difficult, creating a harsh operating environment, posing challenges for subsequent liquid treatment, resulting in high environmental hazards and low utilization rates. Developing more economical and environmentally friendly green recovery processes to improve resource utilization, optimize the operating environment, and enhance economic efficiency is of great significance.

[0003] Therefore, there is an urgent need to provide a method for recovering copper from converter slag. This method can recover copper from converter slag with a high copper recovery rate, which can improve resource utilization and economic benefits, reduce pollution emissions, and avoid the large-scale use of acid, making it green and environmentally friendly. Summary of the Invention

[0004] This invention aims to solve one or more technical problems existing in the prior art, and at least provide a beneficial option or create conditions. This invention provides a method for recovering copper from converter slag. This method recovers copper from converter slag with a high copper recovery rate, which can improve resource utilization and economic benefits, reduce pollution emissions, and avoid the large-scale use of acid, making it environmentally friendly.

[0005] The inventive concept of this invention is as follows: This invention uses converter slag, a byproduct of pyrometallurgical copper smelting, as raw material. It employs a leaching solution containing complexing agents and inhibitors for metal ion leaching, avoiding the use of large amounts of acid, making it green, environmentally friendly, and beneficial to human health and the environment. The complexing agent forms complex ions with the metal ions and dissolves in the leaching solution. This complexation process does not destroy the effective leaching components in the leaching solution. The inhibitors suppress the entry of iron ions into the solution, reducing iron leaching from the converter slag and ensuring that more complexing agent can be used for copper complexation, thus increasing the copper leaching rate. After leaching, copper in the leaching solution is recovered using electrowinning. Through a single-stage leaching, single-stage electrowinning, and two-stage leaching and two-stage electrowinning process, copper in the converter slag is fully leached and recovered through electrowinning. The copper recovery rate is greater than 94%, even reaching 95%, improving resource utilization and economic benefits while reducing pollution emissions. Furthermore, the complexing agent is recyclable, and both the electrowinning solution and the leaching solution can be recycled during the leaching and electrowinning processes, effectively reducing process costs, improving economic efficiency, and reducing wastewater discharge.

[0006] Therefore, a first aspect of the present invention provides a method for recovering copper from converter slag.

[0007] Specifically, a method for recovering copper from converter slag includes the following steps:

[0008] (1) Preparation of leachate: Mix the complexing agent and the inhibitor to obtain the leachate;

[0009] (2) First stage leaching: The converter slag is added to the leaching solution obtained in step (1), heated, leached, and filtered to obtain a first leaching solution and a first leaching residue;

[0010] (3) Electrowinning: The first immersion solution obtained in step (2) is added to the cathode chamber of the electrowinning device as the electrowinning solution, electrowinning is performed, and the solution in the cathode chamber is filtered to obtain a first electrowinning solution and a first electrowinning copper powder.

[0011] (4) Two-stage leaching: The first leaching residue obtained in step (2) is used as raw material, and the first electrowinning liquid obtained in step (3) is used as leaching liquid. The first leaching residue is added to the first electrowinning liquid, heated, leached, and filtered to obtain the second leaching liquid and the second leaching residue.

[0012] (5) Two-stage electrowinning: The second immersion solution obtained in step (4) is added to the cathode chamber of the electrowinning device as the electrowinning solution, electrowinning is performed, and the solution in the cathode chamber is filtered to obtain the second-stage electrowinning solution and the second-stage electrowinning copper powder.

[0013] (6) Complexing agent recovery: Add the acid solution to the two-stage electrowinning solution obtained in step (5), precipitate, filter, and complete the recovery of the complexing agent;

[0014] In step (1), the inhibitor includes sodium carbonate.

[0015] Preferably, in step (1), the complexing agent and the inhibitor are added to water and mixed to obtain an extract.

[0016] Preferably, in step (1), the complexing agent is selected from at least one of ethylenediaminetetraacetic acid (EDTA) and EDTA salt.

[0017] Specifically, when the complexing agent is EDTA, because EDTA has low solubility but EDTA sodium salt has high solubility, an alkali needs to be added to EDTA to obtain an EDTA sodium salt solution. After the EDTA sodium salt solution is formed, EDTA is still the agent that provides the complexing effect.

[0018] Preferably, the concentration of the complexing agent is 0.25-0.34 mol / L; and the concentration of the inhibitor is 0.8-1.4 mol / L.

[0019] More preferably, the concentration of the complexing agent is 0.28-0.32 mol / L; and the concentration of the inhibitor is 1.0-1.2 mol / L.

[0020] More preferably, the concentration of the complexing agent is 0.298 mol / L; and the concentration of the inhibitor is 1.132 mol / L.

[0021] Specifically, the complexing agent used in this invention is environmentally friendly, non-toxic and harmless, and can eliminate the absorption and emission pressure of irritating waste gas in traditional processes.

[0022] Specifically, the inhibitor sodium carbonate forms insoluble ferric carbonate with iron ions, inhibiting the entry of iron ions into the leaching solution. This effectively reduces the leaching of iron from the converter slag, ensuring that more complexing agent can be used for copper complexation, thereby increasing the copper leaching rate and improving the purity of the recovered copper.

[0023] Preferably, in step (2), the liquid-to-solid ratio of the leachate and the converter slag is 4.0-6.0:1.

[0024] More preferably, the liquid-to-solid ratio of the leachate to the converter slag is 4.5-5.5:1.

[0025] More preferably, the mass ratio of the leachate to the converter slag is 5:1.

[0026] Preferably, in step (2), the converter slag is ground, passed through a 200-mesh sieve, and then added to the leachate obtained in step (1).

[0027] Preferably, in steps (2) and (4), the temperature is heated to the leaching temperature; the leaching temperature is 12-75℃ and the leaching time is 1.5-6.5h.

[0028] More preferably, the leaching temperature is 15-70℃ and the leaching time is 2-6h.

[0029] Specifically, in step (4), all the leaching residue obtained in step (2) is used as raw material, and all the electrowinning liquid obtained in step (3) is used as leachate.

[0030] Preferably, in steps (2) and (4), after heating to the leaching temperature, oxygen is introduced while stirring to carry out leaching.

[0031] Preferably, in steps (3) and (5), the electrowinning device is a diaphragm electrolyzer; the diaphragm is a cation membrane.

[0032] Specifically, copper in the leaching solution is recovered using the diaphragm electrowinning method. Through the barrier of the cation membrane, the organic components of the complexing agent in the leaching solution do not come into contact with the anode, thus avoiding the loss of the complexing agent due to oxidative decomposition and enabling efficient recycling of the complexing agent components in the leaching solution.

[0033] Preferably, the cathode and anode of the electrodeposition device are both made of high-purity graphite.

[0034] Specifically, in step (3), copper gains electrons at the cathode and deposits metallic copper, i.e., a section of electrolytic copper powder.

[0035] Preferably, in steps (3) and (5), the solution in the anode chamber of the electrowinning device is sodium carbonate; the concentration of the sodium carbonate is 0.8-1.4 mol / L; more preferably, the concentration of the sodium carbonate is 1.0-1.2 mol / L; even more preferably, the concentration of the sodium carbonate is 1.132 mol / L.

[0036] Specifically, the solution in the anode chamber is sodium carbonate, which is consistent with the sodium carbonate used as an inhibitor. The main purpose is to ensure consistent conductivity during electrodeposition.

[0037] Preferably, in steps (3) and (5), the current density of the electrodeposition is 90-330 A / m. 2 .

[0038] More preferably, in steps (3) and (5), the current density of the electrodeposition is 100-300 A / m. 2 .

[0039] Preferably, in step (5), the electrolyte after the second electrowinning is used as the leachate in step (2), and steps (2)-(5) are repeated for recycling.

[0040] Preferably, in step (6), the solution after the second stage of electrowinning is a solution after multiple cycles of leaching and electrowinning, and the recovered complexing agent can be returned to step (1) as a complexing agent component for the preparation of the leaching solution.

[0041] Preferably, in step (6), the acid solution is selected from at least one of sulfuric acid and hydrochloric acid.

[0042] Specifically, the main purpose of adding acid is to adjust the pH.

[0043] Preferably, the pH is 0.2-2.0.

[0044] More preferably, the pH is 0.5-1.0.

[0045] More preferably, the pH is 0.5.

[0046] Preferably, in step (6), the recovered complexing agent is recycled as a raw material in step (1).

[0047] Specifically, based on the physicochemical properties of the complexing agent EDTA, this invention combines precipitation recovery technology to form a precipitate under acidic conditions. This effectively separates the salts and complexing agent components accumulated in the solution after two-stage electrowinning due to multiple leaching cycles, achieving efficient recovery and recycling of the complexing agent, effectively reducing process costs, and further improving economic benefits.

[0048] Preferably, the recovered complexing agent is EDTA. EDTA has low solubility, while sodium EDTA has high solubility. It is necessary to add alkali to EDTA to obtain a sodium EDTA solution. After the sodium EDTA solution is formed, EDTA is still the agent that provides the complexing effect.

[0049] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are as follows:

[0050] (1) This invention uses converter slag, a byproduct of pyrometallurgical copper smelting, as raw material. It employs a leaching solution containing complexing agents and inhibitors to leach metal ions, avoiding the use of large amounts of acid, making it green, environmentally friendly, and beneficial to both humans and the environment. The complexing agent forms complex ions with the metal ions and dissolves in the leaching solution. This complexation process does not destroy the effective leaching components in the leaching solution. The inhibitors suppress the entry of iron ions into the solution, reducing iron leaching from the converter slag and ensuring that more complexing agent can be used for copper complexation, thus increasing the copper leaching rate. After leaching, copper in the leaching solution is recovered using electrowinning. Through a single-stage leaching and electrowinning process, followed by two stages of leaching and electrowinning, the copper in the converter slag is fully leached and recovered through electrowinning. The copper recovery rate is greater than 94%, even reaching 95%, improving resource utilization and economic benefits while reducing pollution emissions. Furthermore, the complexing agent, leaching solution, and electrowinning solution can all be recycled during the leaching and electrowinning processes, effectively reducing process costs, improving economic benefits, and reducing wastewater discharge.

[0051] (2) The present invention combines precipitation and recovery technology to complete the recovery of complexing agent and realize recycling. The complexing agent has good recovery rate and reusability, which can reduce costs and further improve economic benefits.

[0052] (3) The use of the inhibitor in this invention results in a low iron leaching rate, which ensures that more complexing agent is used for copper complexation, thereby increasing the copper leaching rate and stabilizing the copper leaching rate at around 95.0%.

[0053] (4) The solution system of the present invention can be recycled, reducing wastewater discharge, eliminating large amounts of acid and alkali loss, and eliminating irritating gas emissions. It is safe, environmentally friendly, and has excellent economic benefits. Attached Figure Description

[0054] Figure 1 This is a process flow diagram of copper recovery from converter slag according to the present invention;

[0055] Figure 2 This is a schematic diagram of an electrodeposition device. Detailed Implementation

[0056] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0057] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0058] The process flow diagram for recovering copper from converter slag in this invention is as follows: Figure 1 As shown.

[0059] The electrowinning apparatuses in Examples 1-3 all employ diaphragm electrolytic cells; the diaphragms are all cation exchange membranes; and the cathodes and anodes of the electrowinning apparatus are both made of high-purity graphite. A schematic diagram of the electrowinning apparatus is shown below. Figure 2 As shown.

[0060] Example 1

[0061] A method for recovering copper from converter slag includes the following steps:

[0062] (1) Preparation of leachate: 0.298 mol / L EDTA, 1.132 mol / L sodium carbonate, to prepare complex leachate;

[0063] (2) First stage leaching: The copper content in the converter slag is 4.66% and the iron content is 4.33%. According to the liquid-solid ratio of the leaching solution to the converter slag is 5:1, the converter slag (500g) that has been ground and passed through a 200-mesh sieve is added to the leaching solution (2500ml) obtained in step (1), heated to the leaching temperature of 35℃, and oxygen is introduced under stirring to carry out leaching. The leaching time is 5h. After the leaching is completed, the solution is filtered to obtain a first leaching solution and a first leaching residue.

[0064] (3) Electrowinning: The first immersion solution obtained in step (2) is added to the cathode chamber of the electrowinning apparatus, and the anode chamber is a 1.132 mol / L sodium carbonate solution, maintaining a current density of 200 A / m. 2 Electrowinning is performed, and the cathode chamber solution is filtered to obtain a section of electrowinning solution and a section of electrowinning copper powder.

[0065] (4) Two-stage leaching: The first-stage electrowinning liquid obtained in step (3) is used as the leaching liquid, and the first leaching residue is used as the raw material. The first leaching residue is added to the leaching liquid, and the leaching process of step (2) is repeated to obtain the second leaching liquid and the second leaching residue.

[0066] (5) Two-stage electrowinning: The second immersion solution obtained in step (4) is used as the electrowinning solution in the cathode chamber of the electrowinning device. Step (3) is repeated to obtain the second-stage electrowinning solution and the second-stage electrowinning copper powder.

[0067] The copper content in the first leaching solution obtained in step (2) is 5.00 g / L, the copper content in the first electrowinning solution obtained in step (3) is 0.033 g / L, and the leaching residue obtained in step (4) has a residue rate of 56.0%, a copper content of 0.36%, and a leaching rate of 95.6%; the iron content in the second leaching residue is 7.52%, and the iron leaching rate is 2.7%; the copper content in the second leaching solution is 3.95 g / L, indicating that the sodium carbonate inhibitor used in this invention can effectively inhibit the leaching of iron, thereby improving the copper leaching rate. In step (5), the copper content in the second electrowinning solution is 0.027 g / L, and the copper recovery rate is 95%.

[0068] The copper leaching rate is calculated as follows: Copper leaching rate = ((copper content in converter slag raw material - copper content in secondary leaching slag × slag ratio) / copper content in converter slag raw material) × 100%.

[0069] The calculation method for iron leaching rate is as follows: Iron leaching rate = ((Iron content in converter slag raw material - Iron content in secondary leaching slag × slag ratio) / Iron content in converter slag raw material) × 100%.

[0070] The copper recovery rate is calculated as follows: Copper recovery rate = (Copper content in the first leaching solution - Copper content in the solution after the first electrowinning + Copper content in the second leaching solution - Copper content in the solution after the second electrowinning) × Leachate volume / (Copper content in converter slag raw material × Converter slag raw material mass).

[0071] Example 2

[0072] The difference between Example 2 and Example 1 is that Example 2 includes step (6) after step (5), while the rest is the same as Example 1.

[0073] The process in step (6) is as follows:

[0074] Place the two-stage electrowinning solution obtained in step (5) into a beaker, add sulfuric acid while stirring, adjust the pH value to 0.5, stir, let stand, and filter after complete precipitation to obtain EDTA precipitate.

[0075] Based on the obtained EDTA precipitate, and calculated according to the actual recovered mass and the mass of the complexing agent added in step (1), the recovery rate of the complexing agent is 99.0%, indicating that the complexing agent of the present invention can be efficiently recovered, thereby reducing process costs and improving economic benefits.

[0076] The recovery rate of the complexing agent is calculated as follows: Recovery rate of complexing agent = (mass of complexing agent actually recovered / mass of complexing agent added) × 100%.

[0077] Example 3

[0078] The difference between Example 3 and Example 1 is that the complexing agent added when preparing the leachate is the complexing agent recovered in Example 2, and the rest is the same as in Example 1.

[0079] The processing procedure of Example 3 is as follows: the two-stage electrowinning liquid obtained in step (5) is returned to step (2) and used as the leachate of step (2). Steps 2-5 are repeated for a total of 3 cycles. The converter slag in step (2) of each cycle is a new converter slag. After the last cycle, the content of the two-leaching slag obtained in step (4) is analyzed.

[0080] The resulting secondary leaching residue had a slag ratio of 56.5%, a copper content of 0.41%, and a leaching rate of 95.0%. The iron content was 7.46%, with a leaching rate of 2.7%. The copper leaching rate was essentially consistent with that of Example 1, indicating that the solution system of this invention has a high recyclability, reduces wastewater discharge, and effectively improves environmental performance. It also demonstrates that the EDTA complexing agent obtained through recycling in this invention also possesses excellent complexing ability and reusability.

[0081] Comparative Example 1

[0082] A method for recovering copper from converter slag includes the following steps:

[0083] (1) Preparation of leachate: Prepare leachate according to 1.132 mol / L sodium carbonate;

[0084] (2) First stage leaching: The copper content in the converter slag is 4.66% and the iron content is 4.33%. According to the liquid-solid ratio of the leaching solution to the converter slag is 5:1, the converter slag that has been ground and passed through a 200-mesh sieve is added to the leaching solution obtained in step (1), heated to the leaching temperature of 35°C, and oxygen is introduced under stirring to carry out leaching. The leaching time is 5 hours. After the leaching is completed, the solution is filtered to obtain a first leaching solution and a first leaching residue.

[0085] In Comparative Example 1, the leaching solution contained only the inhibitor sodium carbonate and no complexing agent. Consequently, copper ions could not form complexes with the complexing agent and dissolve in the leaching solution. This resulted in a copper content of only 0.1761 g / L in the leaching solution obtained in step 2, with a copper leaching rate of only 2%. The excessively low copper content in the leaching solution reduced the current efficiency of the electrowinning process, hindering its effective execution. This demonstrates that the complexing agent in the leaching solution plays a crucial role in the copper leaching rate.

[0086] Comparative Example 2

[0087] A method for recovering copper from converter slag includes the following steps:

[0088] (1) Preparation of leachate: 0.298 mol / L EDTA, 1.132 mol / L sodium carbonate, to prepare complex leachate;

[0089] (2) First stage leaching: The copper content in the converter slag is 4.66% and the iron content is 4.33%. According to the mass ratio of converter slag to leaching liquid of 5:1, the converter slag that has been ground and passed through a 200-mesh sieve is added to the leaching liquid obtained in step (1), heated to the leaching temperature of 35°C, and oxygen is introduced under stirring to carry out leaching. The leaching time is 5 hours. After the leaching is completed, the solution is filtered to obtain a first leaching liquid and a first leaching residue.

[0090] (3) Electrowinning: Add the first immersion solution obtained in step (2) to a container, place a high-purity graphite electrode, and maintain a current density of 200 A / m. 2 Electrowinning is performed, and the cathode chamber solution is filtered to obtain a section of electrowinning solution and a section of electrowinning copper powder.

[0091] (4) Place the electrowinning solution obtained in step (3) into a beaker, add sulfuric acid while stirring, adjust the pH value to 0.5, stir, and let stand.

[0092] In Comparative Example 2, no diaphragm device was used for electrowinning. In step (4) during the EDTA precipitation process, no obvious precipitation occurred. Based on the physicochemical properties of EDTA, it can be seen that the EDTA component in the solution system has been oxidized and cannot be recycled.

[0093] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for recovering copper from converter slag, characterized in that, The method comprises the following steps: (1) preparation of leaching solution: mixing complexing agent and inhibitor to obtain leaching solution; (2) first-stage leaching: adding converter slag into the leaching solution obtained in step (1), heating, leaching and filtering to obtain first-stage leaching solution and first-stage leaching residue; (3) first-stage electrodeposition: adding the first-stage leaching solution obtained in step (2) into the cathode chamber of an electrodeposition device as electrodeposition solution, electrodeposition, filtering the solution in the cathode chamber to obtain first-stage electrodeposition solution and first-stage electrodeposited copper powder; (4) second-stage leaching: taking the first-stage leaching residue obtained in step (2) as raw material and the first-stage electrodeposition solution obtained in step (3) as leaching solution, adding the first-stage leaching residue into the first-stage electrodeposition solution, heating, leaching and filtering to obtain second-stage leaching solution and second-stage leaching residue; (5) second-stage electrodeposition: adding the second-stage leaching solution obtained in step (4) into the cathode chamber of an electrodeposition device as electrodeposition solution, electrodeposition, filtering the solution in the cathode chamber to obtain second-stage electrodeposition solution and second-stage electrodeposited copper powder; (6) recovery of complexing agent: adding acid solution into the second-stage electrodeposition solution obtained in step (5), precipitating and filtering to complete the recovery of complexing agent. In step (1), the inhibitor is sodium carbonate.

2. The method of claim 1, wherein, In step (1), the complexing agent is at least one selected from ethylenediaminetetraacetic acid and ethylenediaminetetraacetate.

3. The method of claim 1, wherein, In step (2), the liquid-solid ratio of the leaching solution to the converter slag is 4.0-6.0:

1.

4. The method of claim 1, wherein, In steps (2) and (4), the temperature is heated to leaching temperature during heating; the leaching temperature is 12-75℃, and the leaching time is 1.5-6.5h.

5. The method of claim 1, wherein, In steps (3) and (5), the electrodeposition device is a diaphragm electrolytic cell; the diaphragm is a cation membrane.

6. The method of claim 1, wherein, In step (3) and step (5), the current density of the electrodeposition is 90-330 A / m 2 .

7. The method according to any one of claims 1 to 6, characterized in that, In step (5), the second-stage electrodeposition solution is used as the leaching solution of step (2), and steps (2)-(5) are repeated to recycle.

8. The method of claim 7, wherein, In step (6), the second-stage electrodeposition solution is the solution after multiple cycles of leaching-electrodeposition, and the recovered complexing agent can be returned to step (1) as a component of the complexing agent for preparation of leaching solution.

9. The method of claim 1, wherein, The acid solution is at least one selected from sulfuric acid and hydrochloric acid.

10. Use of the method according to any one of claims 1-9 in the field of smelting.

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