Method for separating and recycling copper-tin alloy through step-by-step electro-deposition

Abstract

The invention provides a method for separating and recovering a copper-tin alloy through step-by-step electro-deposition, which comprises the following steps of: dissolving the copper-tin alloy in an acid solution, and controlling the hydrogen ion concentration to be 1-6mol / L and the reaction temperature to be 50-80 DEG C to generate a mixed salt solution containing copper and tin; a composite additive is added, so that the stability in the electro-deposition process is improved; copper is selectively deposited under the conditions that the temperature ranges from 20 DEG C to 60 DEG C and the voltage ranges from-0.2 V to-0.5 V (vs.Ag / AgCl), and crude copper (the purity is larger than or equal to 98.0%) and copper removal electrolyte are obtained; the copper removal electrolyte is subjected to tin electro-deposition under the condition of 50 A / m-2000 A / m, and crude tin (the purity is larger than or equal to 99.9%) and tail liquid are obtained; the tail liquid is purified and circularly used for the dissolving process. According to the method, efficient copper-tin separation is achieved through the composite additive and potential control, purity is high, energy consumption is low, tail liquid is recycled, no waste liquid is discharged, and the method is suitable for industrial popularization.

Description

Technical Field

[0001] The invention belongs to the technical field of non-ferrous metal secondary resource recovery, and specifically relates to a method for realizing efficient separation of copper and tin and metal recovery by utilizing a step-by-step electrodeposition process. Background Art

[0002] Copper and tin are important strategic metals with a wide range of applications. In the field of non-ferrous metal resource recycling, the separation and recovery of copper-tin alloys is a key link in the comprehensive utilization of secondary resources. The main sources of copper-tin alloys include electronic scrap, tinned copper wire, industrial waste slag, and scrap mechanical parts and artworks. For example, common tin solders in electronic scrap (usually copper-tin alloys) and tinned copper wires in scrap cables are rich in copper-tin alloys. In addition, high-copper tin slag produced during tin smelting is also rich in copper and tin. Recycling copper and tin in copper-tin alloy materials can not only achieve efficient recycling of resources, but also significantly increase their economic value. At the same time, this process is in line with the concept of sustainable development and has important practical significance.

[0003] Since the vapor pressures of copper and tin are similar, it is difficult to achieve effective separation and recovery of copper-tin alloys by ordinary vacuum distillation. In the prior art, copper-tin separation usually adopts the method of adding a sulfiding agent to convert tin into stannous sulfide (SnS) with strong volatility, thereby achieving the purpose of removing tin. For example, the Chinese invention patent with application number 201710802746.8 discloses a method for separating copper-tin alloys by circulating stannous sulfide. The method melts the copper-tin alloy at normal pressure and adds SnS, then removes the slag after cooling to obtain crude tin and sulfur slag containing Cu < 0.1%; then, metallic tin is selectively added or not added to the sulfur slag, and metallic copper and SnS are separated by vacuum distillation. The Chinese invention patent with application number 202211126984.9 discloses a method for recovering copper, tin, zinc and lead from tin bronze. By adding cuprous sulfide to react with tin to generate stannous sulfide and copper, stannous sulfide is separated by vacuum distillation, and the remaining copper is blown at 1200-1300℃ to obtain crude copper. However, the existing methods face many challenges in treating copper-tin alloys with high tin content (>15%). The efficiency of the sulfidation reaction in high-tin alloys is limited by mass transfer resistance, especially in the molten state, where uneven contact between the sulfiding agent and tin significantly reduces the reaction efficiency. At the same time, the use of a large amount of sulfiding agent may lead to an increase in residual impurities in the system, which further affects the purity of subsequent products. In addition, the vacuum method has problems such as high energy consumption, high equipment requirements and complex process flow, which seriously restrict its application in large-scale industrialization. The environmental risks that may be brought about by high-temperature sulfidation reactions and treatment processes also need to be further optimized and controlled. Therefore, the development of a simple, efficient, environmentally friendly and economical separation method to achieve efficient separation and recovery of copper and tin is a key issue that needs to be urgently solved in the current technical field. Summary of the invention

[0004] The purpose of the present invention is to provide a method for separating and recovering copper-tin alloy by step-by-step electrodeposition to solve the problems existing in the above-mentioned prior art.

[0005] A method for separating and recovering a copper-tin alloy by stepwise electrodeposition comprises the following steps: (1) Dissolution of copper-tin alloy Put the copper-tin alloy into a dissolving device, add an inorganic acid solution, and react at 50°C to 80°C to generate a mixed salt solution containing copper and tin; (2) Adding composite additives adding the composite additive to the mixed salt solution to obtain a clear solution; (3) Constant potential selective deposition of copper The clarified solution is introduced into an electrolytic device, with a copper sheet as the cathode and an inert anode as the anode, and selective copper electrodeposition is performed under the conditions of an electrolyte temperature of 20°C to 60°C and a cathode electrode potential of -0.2 V to -0.5 V (Vs. Ag / AgCl) to obtain crude copper and a copper-depleted electrolyte; (4) Tin deposition recovery The decopperized electrolyte was transferred to another electrolysis device and heated at 50A / m 2 ~2000A / m 2 Electrodepositing tin at a current density of 20°C to 60°C to obtain crude tin and tail liquid; (5) Tail liquid treatment and recycling After the tail liquid is purified, it is recycled to dissolve the copper-tin alloy.

[0006] In step (1), the mass fraction of copper in the copper-tin alloy is 1% to 99%, and the mass fraction of tin is 1% to 99%.

[0007] In step 1, the added acid may be one or more of sulfuric acid, hydrochloric acid and nitric acid, and more preferably sulfuric acid.

[0008] In step 1, the solution must be kept strongly acidic with a hydrogen ion concentration of 1.0 mol / L to 6.0 mol / L to prevent divalent tin ions (Sn 2+ ) undergoes hydrolysis during the dissolution process to generate tetravalent tin dioxide (SnO2) solid, which adheres to the metal surface and affects further dissolution.

[0009] In step 2, a composite additive is added to the mixed salt solution to increase the actual potential difference, thereby achieving the purpose of selective copper deposition. The standard electrode potentials of copper and tin are +0.34V (Cu²⁺ / Cu) and -0.14V (Sn²⁺ / Sn), respectively. Due to the small potential difference, co-deposition may occur when the concentrations of the two metal ions are high. After adding the composite additive, the selective deposition efficiency of copper is significantly improved.

[0010] In step 2, the components of the composite additive used are a grain refiner and a complexing agent.

[0011] In step 2, the grain refiner in the composite additive is gelatin, thiourea, polyethylene glycol and chloride ion (Cl - ) with a concentration of 1 to 50 ppm; In step 2, the complexing agent in the composite additive used is a mixture of one or more of ethylenediaminetetraacetic acid (EDTA), sodium citrate (C6H5Na3O7), ammonium fluoride (NH4F) and tartaric acid (C4H6O6). The concentration is 0.5 to 1.5 times the total molar amount of copper and stannous ions finally obtained; In step 3, the end point of electrodeposition is determined by monitoring the change in current density. 2 ~20A / m 2 The electrodeposition is stopped at this time to obtain crude copper and significantly reduce the residual concentration of copper ions in the copper removal electrolyte.

[0012] In step 4, when the tin ion concentration drops to 1 g / L to 10 g / L, stop the electrolysis to reduce the hydrogen evolution side reaction (2H + +2e → H2), thereby improving the current efficiency and obtaining coarse tin.

[0013] The present invention has the following technical effects: (1) Efficient separation: By adding composite additives and precisely controlling the electrode potential, efficient and selective deposition of copper and tin is achieved, metal co-deposition is avoided, separation efficiency is improved, and high-purity crude copper (≥98.0%) and crude tin (≥99.9%) are obtained.

[0014] (2) Green and environmentally friendly: The tail liquid can be recycled after purification, without any waste liquid discharge, thus reducing environmental pollution and the consumption of raw materials, which is in line with the concept of sustainable development.

[0015] (3) Low energy consumption: The entire process is operated under low temperature conditions (20℃~80℃). Compared with the traditional pyrometallurgical process, energy consumption is reduced by more than 30%, effectively saving energy.

[0016] (4) Strong economy: The optimized additive ratio and electrolytic parameters significantly reduce the operating cost. The process is simple and efficient, suitable for large-scale industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0018] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention. Example

[0019] A method for separating and recovering copper-tin alloy by step-by-step electrodeposition: (1) Dissolution of copper-tin alloy Take 50g of copper-tin alloy (copper content 15%, tin content 85%), put it into a 1L beaker, add 150g / L sulfuric acid solution, liquid volume 500mL. Control the temperature at 50℃, stir until the copper-tin alloy is completely dissolved, and obtain a mixed salt solution containing copper ions (15g / L) and tin ions (85g / L). The solution is strongly acidic, which effectively prevents the hydrolysis of tin ions to form tin dioxide (SnO2).

[0020] (2) Adding composite additives Add the composite additive (10 ppm gelatin, 20 ppm thiourea and 50 ppm chloride ion (Cl - ); 135g / L tartaric acid), stir for 30 minutes to ensure that the composite additive is completely dissolved.

[0021] (3) Constant potential selective deposition of copper The clarified solution was introduced into the electrolytic cell, with a pure copper sheet as the cathode and a titanium-based precious metal coated electrode as the anode. The electrolyte temperature was controlled to be 40°C and the cathode electrode potential was -0.3V (vs. Ag / AgCl). Under this condition, oxygen evolution reaction occurred at the anode (2H2O → O2 + 4H⁺ + 4e⁻), and copper was selectively deposited at the cathode (Cu²⁺ + 2e⁻ → Cu). After 6 hours of reaction, when the current density dropped to 10A / m², the reaction was stopped to obtain crude copper (purity ≥98.0%, mass about 7.3g), and the copper ion concentration in the decopperized electrolyte was less than 0.3g / L.

[0022] (4) Tin deposition recovery The decoppered electrolyte was transferred to another electrolytic cell with a current density of 300A / m² and an electrolyte temperature of 40°C. Oxygen evolution continued at the anode and tin was deposited at the cathode (Sn²⁺ + 2e⁻ → Sn). After 6 hours of reaction, when the tin ion concentration dropped to 5g / L, the electrolysis was stopped to obtain crude tin (purity ≥99.9%, mass about 40.0 g).

[0023] (5) Tail liquid treatment and recycling After the tail liquid is neutralized to remove impurities, it is circulated back to the dissolution equipment and used for the dissolution of the next batch of copper-tin alloy, ensuring efficient use of resources and reducing waste liquid discharge. Example

[0024] A method for separating and recovering copper-tin alloy by step-by-step electrodeposition: (1) Dissolution of copper-tin alloy Take 50 g of copper-tin alloy (copper content 50%, tin content 50%), put it into a 1L beaker, add 90 g / L sulfuric acid solution, liquid volume 500mL. Control the temperature at 60℃ and stir until the copper-tin alloy is completely dissolved. A mixed salt solution containing copper ions (50g / L) and tin ions (50g / L) is obtained. The solution is strongly acidic, which effectively prevents the hydrolysis of tin ions to form tin dioxide (SnO2).

[0025] (2) Adding composite additives Add the composite additive (10 ppm gelatin, 20 ppm polyethylene glycol and 50 ppm chloride ion (Cl - ); 150g / L EDTA). Stir for 40 minutes to ensure that the composite additive is completely dissolved.

[0026] (3) Constant potential selective deposition of copper The clarified solution was introduced into the electrolytic cell, with a pure copper sheet as the cathode and a ruthenium-iridium-coated titanium anode as the anode. The electrolyte temperature was controlled to be 60°C and the cathode electrode potential was -0.3V (vs. Ag / AgCl). After 20 hours of electrolysis, when the current density dropped to 5A / m², the reaction was stopped to obtain crude copper (purity ≥98.0%, mass about 24.9g). The copper ion concentration in the decoppering electrolyte was less than 0.3g / L.

[0027] (4) Tin deposition recovery The decoppered electrolyte was transferred to another electrolytic cell with a current density of 2000A / m² and an electrolyte temperature of 60°C. After 0.5 hours of reaction, when the tin ion concentration dropped to 5g / L, the electrolysis was stopped to obtain crude tin (purity ≥99.9%, mass about 22.0g).

[0028] (5) Tail liquid treatment and recycling After the tail liquid is neutralized to remove impurities, it is circulated back to the dissolution equipment and used for the dissolution of the next batch of copper-tin alloy, ensuring efficient use of resources and reducing waste liquid discharge. Example

[0029] A method for separating and recovering copper-tin alloy by step-by-step electrodeposition: (1) Dissolution of copper-tin alloy Take 50g of copper-tin alloy (copper content 15%, tin content 85%), put it into a 1L beaker, add 150g / L sulfuric acid solution, liquid volume 500mL. Control the temperature at 60℃ and stir until the copper-tin alloy is completely dissolved. A mixed salt solution containing copper ions (15g / L) and tin ions (85g / L) is obtained. The solution is strongly acidic, which effectively prevents the hydrolysis of tin ions to form tin dioxide (SnO2).

[0030] (2) Adding composite additives Add the composite additive (50 ppm gelatin, 10 ppm polyethylene glycol and 30 ppm chloride ion (Cl - ); 135g / L tartaric acid). Stir for 30 minutes to ensure that the composite additive is completely dissolved.

[0031] (3) Constant potential selective deposition of copper The clarified solution was introduced into the electrolytic cell, with a pure copper sheet as the cathode and a ruthenium-iridium-coated titanium anode as the anode. The electrolyte temperature was controlled to be 20°C and the cathode electrode potential was -0.4V (vs. Ag / AgCl). After 3 hours of reaction, when the current density dropped to 20A / m², the reaction was stopped to obtain crude copper (purity ≥98.0%, mass about 7.4g). The copper ion concentration in the decoppering electrolyte was less than 0.3g / L.

[0032] (4) Tin deposition recovery The decoppered electrolyte was transferred to another electrolytic cell with a current density of 500A / m² and an electrolyte temperature of 20°C. After 6 hours of reaction, when the tin ion concentration dropped to 8g / L, the electrolysis was stopped to obtain crude tin (purity ≥99.9%, mass about 38.3g).

[0033] (5) Tail liquid treatment and recycling After the tail liquid is neutralized to remove impurities, it is circulated back to the dissolution equipment and used for the dissolution of the next batch of copper-tin alloy, ensuring efficient use of resources and reducing waste liquid discharge. Example

[0034] A method for separating and recovering copper-tin alloy by step-by-step electrodeposition: (1) Dissolution of copper-tin alloy Take 50 g of copper-tin alloy (copper content 85%, tin content 15%), put it into a 1L beaker, add 90 g / L sulfuric acid solution, liquid volume 500mL. Control the temperature at 80℃ and stir until the copper-tin alloy is completely dissolved. A mixed salt solution containing copper ions (85g / L) and tin ions (15g / L) is obtained. The solution is strongly acidic, which effectively prevents the hydrolysis of tin ions to form tin dioxide (SnO2).

[0035] (2) Adding composite additives Add the composite additive (20 ppm gelatin, 10 ppm thiourea and 30 ppm chloride ion (Cl - )、35 g / L NH4F). Stir for 40 minutes to ensure that the composite additive is completely dissolved.

[0036] (3) Constant potential selective deposition of copper The clarified solution was introduced into the electrolytic cell, with a pure copper sheet as the cathode and a ruthenium-iridium-coated titanium anode as the anode. The electrolyte temperature was controlled to be 60°C and the cathode electrode potential was -0.3V (vs. Ag / AgCl). After 20 hours of electrolysis, when the current density dropped to 5A / m², the reaction was stopped to obtain crude copper (purity ≥98.0%, mass about 42.4g). The copper ion concentration in the decoppering electrolyte was less than 0.3g / L.

[0037] (4) Tin deposition recovery The decopperized electrolyte was transferred to another electrolytic cell with a current density of 50A / m² and an electrolyte temperature of 60°C. After 60 hours of reaction, when the tin ion concentration dropped to 8g / L, the electrolysis was stopped to obtain crude tin (purity ≥99.9%, mass about 3.5g).

[0038] (5) Tail liquid treatment and recycling After the tail liquid is neutralized to remove impurities, it is circulated back to the dissolution equipment and used for the dissolution of the next batch of copper-tin alloy, ensuring efficient use of resources and reducing waste liquid discharge.

[0039] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for separating and recovering copper-tin alloy by step-by-step electrodeposition, characterized in that: The following steps are involved: (1) Dissolution of copper-tin alloy: Place the copper-tin alloy in a dissolution device, add one or more of sulfuric acid, hydrochloric acid and nitric acid, adjust the hydrogen ion concentration to 1.0 mol / L to 6.0 mol / L, and react at 50°C to 80°C to generate a mixed salt solution containing copper and tin; (2) Adding composite additives: Add the composite additives to the mixed salt solution and stir thoroughly to obtain a clear solution; (3) Selective copper deposition at constant potential: introducing the clarified solution obtained in step (2) into an electrolytic device, using a copper sheet as a cathode and an inert anode as an anode, selective copper deposition is performed at 20°C to 60°C and an electrode potential of -0.2 V to -0.5 V to obtain crude copper and a copper-depleted electrolyte; (4) Tin deposition recovery: The copper-removing electrolyte produced in step (3) is transferred to another electrolysis device and the current density is 50A / m 2 ~2000A / m 2 and electro-depositing tin at 20°C to 60°C to obtain crude tin and tail liquid; (5) Tail liquid treatment and recycling: After the tail liquid in step (4) is purified, it is recycled back to step (1) for dissolving the copper-tin alloy.

2. The method according to claim 1, characterized in that: In the step (1), the mass fraction of copper in the copper-tin alloy is 1% to 99%, and the mass fraction of tin is 1% to 99%.

3. The method according to claim 1, characterized in that The composite additive used in step (1) comprises a grain refiner and a complexing agent.

4. The method according to claim 1, characterized in that The grain refiner in the composite additive used in step (1) is one or more of gelatin, thiourea, polyethylene glycol and chloride ion, and the concentrations thereof are 10 to 50 ppm respectively.

5. The method according to claim 1, characterized in that The complexing agent in the composite additive used in step (1) is a mixture of one or more of ethylenediaminetetraacetic acid, sodium citrate, ammonium fluoride and tartaric acid, and the concentration is 0.5 to 1.5 times the total molar amount of copper and stannous ions finally obtained.

6. The method according to claim 1, characterized in that The end point of the electrodeposition in step (3) is determined by the change in current density. When the current density drops to 5 A / m 2 ~20A / m 2 When , the electrodeposition is stopped.

7. The method according to claim 1, characterized in that In the step (4), when the tin ion concentration drops to 1 g / L to 10 g / L, the electrodeposition of tin is stopped to avoid the occurrence of hydrogen evolution side reaction.

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