Method for removing arsenic from a copper sulfate solution

Abstract

The application discloses a method for removing arsenic from a copper sulfate solution, which comprises an oxidation and arsenic removal step, and specifically comprises the following steps: adding an arsenic-containing copper sulfate solution to be treated into an oxidizing agent to obtain material a through stirring reaction; adding an arsenic removal agent into the material a, adding a pH regulator to adjust the pH value of the solution to 3.5-4.5 to perform an arsenic removal reaction, and performing solid-liquid separation after the reaction to obtain arsenate precipitate and copper sulfate solution after arsenic removal; and the arsenic removal agent is iron sulfate. The application can guarantee product quality, optimize the process, reduce copper loss, protect stable operation of equipment, reduce comprehensive cost, eliminate arsenic pollution and compliance risks, and promote green and high-quality development of the copper smelting and deep processing industry.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically relating to a method for removing arsenic from copper sulfate solution. Background Technology

[0002] Arsenic impurities in copper sulfate solution can lead to the accumulation of impurities in electrolytic copper cathodes, brittleness of copper materials, decreased conductivity, and surface particle defects, failing to meet the standards for high-purity electrolytic copper and electronic-grade copper sulfate. Furthermore, arsenic interferes with electrodeposition and crystallization processes, reducing direct copper recovery. Its complexes and insoluble arsenic salts can also corrode electrodes and pipelines, increasing maintenance and downtime costs. Moreover, arsenic is highly toxic, posing significant environmental and safety compliance risks. Therefore, arsenic removal from copper sulfate solution is essential to ensure product quality, optimize processes, reduce copper loss, protect equipment stability, lower overall costs, eliminate arsenic pollution and compliance risks, and promote green and high-quality development in the copper smelting and deep processing industry. Summary of the Invention

[0003] The purpose of this invention is to provide a method for removing arsenic from copper sulfate solution.

[0004] The objective of this invention is achieved by the method for removing arsenic from copper sulfate solution, which includes oxidation and arsenic removal steps, specifically including: A. Oxidation: Add the arsenic-containing copper sulfate solution to be treated to an oxidant and stir to react to obtain material a; B. Arsenic removal: Add arsenic removal agent to material a, add pH adjuster to adjust the pH of the solution to 3.5~4.5 to carry out the arsenic removal reaction. After the reaction is completed, solid and liquid separation is performed to obtain arsenate precipitate and arsenic-removed copper sulfate solution. The arsenic removal agent is ferric sulfate, polyferric sulfate, ferric hydroxide, or ferric oxide.

[0005] Specifically, an oxidant (one or more of hydrogen peroxide, ozone, air, oxygen, sodium chlorate, sodium hypochlorite, and sodium persulfate) at a mass ratio of 10-30 times the arsenic mass is added to an arsenic-containing copper sulfate solution, and the mixture is stirred for at least 30 minutes. Then, an arsenic removal agent is added, controlling the mass ratio of arsenic to the removal agent in the solution to 1:1-100. The mixed solution is heated to 40-60°C, and an acidic solution (sulfuric acid, hydrochloric acid, nitric acid, etc.) or an alkaline solution (sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonia, etc.) is added to adjust the pH to 3.5-4.5. The reaction is allowed to proceed for 1-2 hours, followed by solid-liquid separation. Arsenate precipitate is removed by filtration, thus completing the removal of arsenic from the copper sulfate solution. Precipitating agents include ferric sulfate, polyferric sulfate, ferric hydroxide, and ferric oxide. This invention ensures product quality meets standards, optimizes processes, reduces copper loss, protects equipment for stable operation, lowers overall costs, eliminates arsenic pollution and compliance risks, and promotes green and high-quality development in the copper smelting and deep processing industry.

[0006] Its technical principle is as follows: This invention removes arsenic from copper sulfate solution using an oxidation-iron salt precipitation / adsorption co-precipitation method. Arsenic in arsenic-containing copper sulfate solutions typically exists in trivalent and pentavalent forms, with trivalent arsenic being more stable and difficult to precipitate. Therefore, an oxidant is first added to oxidize the trivalent arsenic in the solution to pentavalent arsenic, converting it into arsenate, which readily reacts with iron ions. The main reaction can be represented as follows: H3AsO3 + H2O2 → H3AsO4 + H2O After oxidation is complete, iron-based arsenic removal agents such as ferric sulfate, polyferric sulfate, ferric hydroxide, or ferric oxide are added to the system. Ferric sulfate dissociates in solution to produce ferric ions. Fe2(SO4)3→ 2Fe 3+ + 3SO4 2- Pentavalent arsenic exists in solution mainly as arsenate or protonated arsenate, and can react with ferric ions to form insoluble ferric arsenate precipitate. Fe 3+ +AsO4 3- → FeAsO4↓ Meanwhile, under pH conditions of 3.5–4.5, some ferric iron undergoes hydrolysis to form hydrated ferric oxide or ferric hydroxide colloids. Fe 3+ + 3H₂O → Fe(OH)₃↓ + 3H + The generated ferric hydroxide or hydrated ferric oxide has strong adsorption and flocculation effects, and can further fix arsenate in the solution through surface complexation, adsorption co-precipitation, and entrapment. Its function can be simplified as follows: FeOH + H2AsO 4- → FeHAsO 4- + H2O Therefore, the removal of arsenic in this invention is not a single precipitation process, but rather a result of the combined effects of arsenic oxidation and valence conversion, ferric arsenate precipitation, adsorption and co-precipitation of hydrated iron oxide, and flocculation. Controlling the solution pH to 3.5–4.5 facilitates the hydrolysis of ferric iron and its formation of a stable precipitate with arsenate, while preventing excessively high pH levels from causing copper ion hydrolysis and precipitation, thus achieving selective separation of arsenic and copper. After the reaction, solid-liquid separation is performed, with arsenic entering the solid phase as ferric arsenate or arsenic-containing iron oxide precipitates, while copper remains primarily in the liquid phase as copper sulfate. Detailed Implementation

[0007] The present invention will be further described below with reference to embodiments, but this is not intended to limit the present invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0008] The method for removing arsenic from copper sulfate solution according to the present invention includes oxidation and arsenic removal steps, specifically including: A. Oxidation: Add the arsenic-containing copper sulfate solution to be treated to an oxidant and stir to react to obtain material a; B. Arsenic removal: Add arsenic removal agent to material a, add pH adjuster to adjust the pH of the solution to 3.5~4.5 to carry out the arsenic removal reaction. After the reaction is completed, solid and liquid separation is performed to obtain arsenate precipitate and arsenic-removed copper sulfate solution. The arsenic removal agent is ferric sulfate, polyferric sulfate, ferric hydroxide, or ferric oxide.

[0009] The amount of oxidant added in step A is 10 to 30 times the mass of arsenic.

[0010] The oxidant is one or more of hydrogen peroxide, ozone, air, oxygen, sodium chlorate, sodium hypochlorite, and sodium persulfate.

[0011] The stirring reaction time in step A is 20-40 minutes.

[0012] The pH adjuster mentioned in step B is an acidic or alkaline solution.

[0013] The acidic solution is a sulfuric acid solution, a hydrochloric acid solution, or a nitric acid solution.

[0014] The alkaline solution is a sodium hydroxide solution, a sodium carbonate solution, a sodium bicarbonate solution, or an ammonia solution.

[0015] The amount of arsenic removal agent added in step B is 1 to 100 times the mass of arsenic.

[0016] The temperature for the arsenic removal reaction described in step B is 40~60℃.

[0017] The arsenic removal reaction time described in step B is 1-2 hours.

[0018] The present invention will be further described below with reference to specific embodiments: Comparative Example 1 Chinese patent CN100529124C discloses a method for deep arsenic removal using copper sulfate solution. The method involves taking 1L of copper sulfate solution (Cu: 120g / L, As: 0.26g / L), adding 0.39g of sodium ferric sulfate residue, adjusting the pH to 0.5 with 80g / L sodium carbonate solution, heating to 70℃, adding 0.43g of sodium chlorate, maintaining the temperature for oxidation for 1 hour, adjusting the pH to 2.5 with 40g / L sodium carbonate, and then adjusting the pH to 3.5 with 15g / L ammonium bicarbonate. After cooling and filtration, the filtrate composition is: Cu: 108.31g / L, As: 0.00091g / L.

[0019] Example 1

[0020] Take a copper sulfate solution with an arsenic content of 0.121 g / L, heat it to 60℃, add hydrogen peroxide with a mass of 10 times that of arsenic while stirring, and react for 60 min at a stirring speed of 50 r / min. Then add the arsenic removal agent polyferric sulfate, controlling the mass ratio of arsenic to arsenic removal agent in the solution to 1:1, and react for 1.5 h. After the reaction is completed, separate the solid and liquid, and the filter residue is arsenate precipitate. The arsenic content in the filtrate is reduced to 0.00057 g / L.

[0021] Example 2

[0022] Take a copper sulfate solution with an arsenic content of 0.193 g / L, heat it to 40℃, add air with a mass of 30 times the arsenic mass and stir for 30 min at a stirring speed of 200 r / min, then add ferric sulfate as an arsenic removal agent, controlling the mass ratio of arsenic to arsenic removal agent in the solution to 1:100, and react for 1 h. After the reaction is completed, separate the solid and liquid, and the filter residue is arsenate precipitate. The arsenic content in the filtrate is reduced to 0.00073 g / L.

[0023] Example 3

[0024] Take a copper sulfate solution with an arsenic content of 0.154 g / L, heat it to 50℃, add ozone (20 times the mass of arsenic) while stirring, and react for 50 min at a stirring speed of 110 r / min. Then add ferric hydroxide as an arsenic removal agent, controlling the mass ratio of arsenic to arsenic removal agent in the solution to 1:50, and react for 1.3 h. After the reaction is complete, separate the solid and liquid, and the filter residue is arsenate precipitate. The arsenic content in the filtrate is reduced to 0.00061 g / L.

[0025] Example 4

[0026] Take a copper sulfate solution with an arsenic content of 0.168 g / L, heat it to 55℃, add sodium hypochlorite (15 times the mass of arsenic) while stirring, and react for 50 min at a stirring speed of 180 r / min. Then add arsenic removal agent iron oxide, controlling the mass ratio of arsenic to arsenic removal agent in the solution to 1:60, and react for 1.2 h. After the reaction is completed, separate the solid and liquid, and the filter residue is arsenate precipitate. The arsenic content in the filtrate is reduced to 0.00059 g / L.

Claims

1. A method for removing arsenic from copper sulfate solution, characterized in that, The method for removing arsenic from copper sulfate solution includes oxidation and arsenic removal steps, specifically including: A. Oxidation: Add the arsenic-containing copper sulfate solution to be treated to an oxidant and stir to react to obtain material a; B. Arsenic removal: Add arsenic removal agent to material a, add pH adjuster to adjust the pH of the solution to 3.5~4.5 to carry out the arsenic removal reaction. After the reaction is completed, solid and liquid separation is performed to obtain arsenate precipitate and arsenic-removed copper sulfate solution. The arsenic removal agent is ferric sulfate, polyferric sulfate, ferric hydroxide, or ferric oxide.

2. The method for removing arsenic from copper sulfate solution according to claim 1, characterized in that, The amount of oxidant added in step A is 10 to 30 times the mass of arsenic.

3. The method for removing arsenic from copper sulfate solution according to claim 1 or 2, characterized in that, The oxidant is one or more of hydrogen peroxide, ozone, air, oxygen, sodium chlorate, sodium hypochlorite, and sodium persulfate.

4. The method for removing arsenic from copper sulfate solution according to claim 1, characterized in that, The stirring reaction time in step A is 20-40 minutes.

5. The method for removing arsenic from copper sulfate solution according to claim 1, characterized in that, The pH adjuster mentioned in step B is an acidic or alkaline solution.

6. The method for removing arsenic from copper sulfate solution according to claim 5, characterized in that, The acidic solution is a sulfuric acid solution, a hydrochloric acid solution, or a nitric acid solution.

7. The method for removing arsenic from copper sulfate solution according to claim 5, characterized in that, The alkaline solution is a sodium hydroxide solution, a sodium carbonate solution, a sodium bicarbonate solution, or an ammonia solution.

8. The method for removing arsenic from copper sulfate solution according to claim 1, characterized in that, The amount of arsenic removal agent added in step B is 1 to 100 times the mass of arsenic.

9. The method for removing arsenic from copper sulfate solution according to claim 1, characterized in that, The temperature for the arsenic removal reaction described in step B is 40~60℃.

10. The method for removing arsenic from copper sulfate solution according to claim 1, characterized in that, The arsenic removal reaction time described in step B is 1-2 hours.