Impurity removal method for copper electrolysis barren solution

Abstract

The invention belongs to the technical field of metallurgy, and relates to a copper electrolysis barren solution impurity removal method which comprises the following steps: S1, adding an oxidizing agent and bismuth trioxide into a copper electrolysis barren solution, and after reaction, carrying out solid-liquid separation to obtain oxidizing slag and a primary impurity removal solution; and S2, adding lead carbonate and lead oxide into the primary impurity removal liquid obtained in the step S1, and reacting to obtain precipitation slag and secondary impurity removal liquid. And in the secondary impurity removal liquid, the As concentration is less than or equal to 0.1 g / L, the Bi concentration is less than or equal to 0.05 g / L, and the Sb concentration is less than or equal to 0.05 g / L, so that the requirement that the copper electrolysis barren solution is returned for electrolysis after impurity removal can be met, meanwhile, the environmental pollution caused by direct discharge is avoided, and the economic benefit and the environmental benefit are remarkable.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallurgy, and particularly relates to a method for removing impurities from lean copper electrolyte. Background Art

[0002] The copper anode plates produced by copper pyrometallurgical refining and casting usually contain about 0.50% impurities. During the electrolytic refining process, due to their different electrochemical properties, these impurities have different fates, and thus have different effects on the electrolytic process. The core goal of electrolytic refining is to make copper precipitate in large quantities on the cathode as much as possible, while making the impurity elements mainly concentrated in the anode slime. In copper anode plates, the main impurity elements with similar potentials to copper include arsenic (As), antimony (Sb), and bismuth (Bi). These elements may either electrochemically dissolve on the anode together with copper or precipitate on the cathode together with copper ions during the electrolytic process, thus significantly affecting the quality of cathode copper.

[0003] In the traditional purification process of lean copper electrolyte, electrowinning is the core purification technology. This method is based on the difference in precipitation potentials of copper ions at different concentrations to achieve the goals of purification and impurity removal. As the electrolytic process continues, once the copper ion concentration drops to a specific threshold, impurity ions will precipitate on the cathode, forming so-called black copper mud. Usually, this black copper mud is recycled to the pyrometallurgical system for further treatment. However, a large number of harmful impurity elements contained in the black copper mud, such as arsenic (As), antimony (Sb), bismuth (Bi), etc., will gradually accumulate in the pyrometallurgical system, ultimately affecting the product quality. In order to avoid the generation of a large amount of black copper mud, researchers began to explore new purification methods, such as using the precipitation method to remove impurity ions from the electrolyte. Although the precipitation method is easy to operate, it faces challenges, including the complex preparation process of the precipitant, limited impurity removal effect, high production cost, and large amount of subsequent treatment of the precipitate and difficulty in recycling. In addition, some precipitation methods may introduce new impurity ions, and these factors together limit the application of the precipitation method in the purification of industrial electrolyte. Summary of the Invention

[0004] In view of the above deficiencies of the prior art, the present invention provides a method for removing impurities from lean copper electrolyte.

[0005] The specific technical solution is as follows: A method for removing impurities from lean copper electrolyte, comprising the following steps: S1 Adding an oxidant and bismuth trioxide to the lean copper electrolyte, and after reaction, performing solid-liquid separation to obtain oxidation slag and a primary impurity-removed liquid; S2 Adding lead carbonate and lead oxide to the primary impurity-removed liquid obtained in step S1, and after reaction, obtaining precipitation slag and a secondary impurity-removed liquid.

[0006] Wherein, the lean copper electrolyte comes from a copper electrolysis system.

[0007] Specifically, the main component contents in the lean electrolyte for copper electrolysis are as follows: Cu 2+ The concentration is 45 - 48 g / L, the concentration of H2SO4 is 180 - 200 g / L, the concentration of As is ≤ 5.0 g / L, the concentration of Bi is ≤ 0.5 g / L, and the concentration of Sb is ≤ 0.5 g / L.

[0008] The reaction mechanism of the present invention is as follows: The present invention adds an oxidant and bismuth trioxide to the lean electrolyte for copper electrolysis to oxidize and remove AsO3 3- and SbO3 3- in the electrolyte, and uses lead carbonate and lead oxide to selectively remove As, Sb, and Bi in the solution.

[0009] In step S1, bismuth trioxide reacts with sulfuric acid to generate Bi 3+ , and at the same time, the oxidant oxidizes AsO3 3- and SbO3 3- in the lean electrolyte for copper electrolysis into AsO4 3- and SbO4 3- , and AsO4 3- and SbO4 3- react with Bi 3+ in the solution to form BiAsO4 and BiSbO4 precipitates respectively. The oxidant is preferably H2O2 (hydrogen peroxide). The main reactions are: H3AsO3 + H2O2 = H3AsO4 + H2O; H3SbO3 + H2O2 = H3SbO4 + H2O; Bi2O3 + 3H2SO4 = Bi2(SO4)3 + 3H2O; 2H3AsO4 + Bi2(SO4)3 = 2BiAsO4↓ + 3H2SO4; 2H3SbO4 + Bi2(SO4)3 = 2BiSbO4↓ + 3H2SO4.

[0010] Among them, in the primary impurity removal solution, the concentration of As is ≤ 0.2 g / L, the concentration of Sb is ≤ 0.1 g / L, and the concentration of Bi is ≤ 8.8 g / L.

[0011] Furthermore, in step S1, the molar ratio of the oxidant to the total amount of As and Sb in the lean electrolyte for copper electrolysis is 2:(0.3 - 0.8), and the molar ratio of the total amount of Bi in bismuth trioxide to the total amount of As and Sb in the lean electrolyte for copper electrolysis is (1 - 1.5):1.

[0012] Furthermore, in step S1, the reaction temperature is 40 - 70 °C, and the reaction time is 0.5 - 3.0 h.

[0013] Preferably, in step S1, the oxidized slag is returned to the rare metal smelting system to recover arsenic, antimony, and bismuth.

[0014] In step S2, lead carbonate and lead oxide are added to the primary impurity removal solution. Lead carbonate and lead oxide react with sulfuric acid to form lead sulfate precipitates respectively, which can selectively remove As, Sb, and Bi in the solution. The main reactions are as follows: PbCO3 + H2SO4 = PbSO4↓ + H2O + CO2↑; PbO + H2SO4 = PbSO4↓ + H2O.

[0015] Among them, due to different raw materials and reaction mechanisms, there will be significant differences in the physical adsorption properties (such as specific surface area, porosity, particle morphology) of the lead sulfate produced. The reaction rate of lead oxide with sulfuric acid is relatively fast, releasing a large amount of heat, and can produce lead sulfate with an irregular, dense blocky or larger particle shape and less internal pores; the reaction of lead carbonate with sulfuric acid is relatively slow, and can form a regular crystal morphology or a flocculent, porous structure. The reaction of lead oxide is intense and releases a large amount of heat, providing an initial high supersaturation, which is conducive to a large number of nucleations and the formation of fine crystal nuclei. The reaction of lead carbonate is relatively slow, releasing carbon dioxide gas, which helps to maintain and prolong the medium supersaturation, is conducive to the continuous and controllable growth of crystal nuclei, and inhibits the intense hard agglomeration caused by instantaneous high supersaturation and high heat. The mixture of the two is more likely to obtain particles with relatively small particle size, more uniform distribution, and significantly reduced agglomeration degree, which is beneficial to improving the adsorption performance of lead sulfate.

[0016] Among them, in the secondary impurity removal solution, the concentration of As ≤ 0.1 g / L, the concentration of Bi ≤ 0.05 g / L, and the concentration of Sb ≤ 0.05 g / L.

[0017] Furthermore, in step S2, the molar ratio of lead carbonate to lead oxide is (1~5):1.

[0018] Furthermore, in step S2, the molar ratio of the total amount of Pb in lead carbonate and lead oxide to the total amount of As, Bi, and Sb in the primary impurity removal solution is (2~5):1.

[0019] Furthermore, in step S2, the reaction temperature is 40~70 °C, and the reaction time is 1.0~4.0 h.

[0020] Preferably, in step S2, the precipitate slag is returned to the lead smelting system to recover lead.

[0021] Preferably, in step S2, the secondary impurity removal solution is supplemented with sulfuric acid and returned to the copper electrolysis system. Among them, the secondary impurity removal solution is supplemented with sulfuric acid and returned to the copper electrolysis system. After electrolysis, the concentrations of impurities such as arsenic, antimony, and bismuth in the electrolyte increase significantly. The part of the electrolyte for purification treatment is the copper electrolysis lean solution, and the copper electrolysis lean solution can be returned to step S1.

[0022] The beneficial effects of the present invention are as follows: First, the present invention uses an oxidant and bismuth trioxide to remove As and Sb from the copper electrolysis lean solution, and then uses lead carbonate and lead oxide to further selectively remove As, Sb, and Bi, so that the concentration of As in the secondary impurity removal solution is ≤0.1 g / L, the concentration of Bi is ≤0.05 g / L, and the concentration of Sb is ≤0.05 g / L. This can meet the requirement of reusing the copper electrolysis lean solution after impurity removal in electrolysis, and at the same time avoid environmental pollution caused by direct external discharge, with remarkable economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a process flow diagram of the method for removing impurities from copper electrolysis lean solution in the specific implementation manner. SPECIFIC IMPLEMENTATION MANNER

[0024] The principles and features of the present invention will be described below in conjunction with examples. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention. The experimental methods used in the following examples are all conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples can be obtained from commercial sources unless otherwise specified. Example 1

[0025] A method for removing impurities from copper electrolysis lean solution, wherein, The copper electrolysis lean solution comes from the copper electrolysis system, specifically the electrolyte with high impurity content produced by the copper electrolysis system. The main component contents are Cu 2+ with a concentration of 45 g / L, H2SO4 with a concentration of 180 g / L, As with a concentration of 4.2 g / L, Bi with a concentration of 0.48 g / L, and Sb with a concentration of 0.42 g / L.

[0026] The method steps are as follows: S1 Add 30 wt% hydrogen peroxide and bismuth trioxide to the copper electrolysis lean solution, react at 40 °C for 3.0 h, and then perform solid-liquid separation to obtain oxidation slag and a primary impurity removal solution. The oxidation slag is returned to the rare metal smelting system to recover arsenic trioxide, antimony trioxide, and bismuth ingots; wherein, the molar ratio of H2O2 in hydrogen peroxide to the total amount of As and Sb in the copper electrolysis lean solution is 2:0.3, the molar ratio of the total amount of Bi in bismuth trioxide to the total amount of As and Sb in the copper electrolysis lean solution is 1:1, the concentration of As in the primary impurity removal solution is 0.18 g / L, the concentration of Sb is 0.08 g / L, and the concentration of Bi is 1.33 g / L; Add lead carbonate and lead oxide to the primary impurity-removing solution obtained in step S1, react at 70 °C for 1.0 h, then obtain a precipitate residue and a secondary impurity-removing solution. The precipitate residue is returned to the lead smelting system for lead recovery, and the secondary impurity-removing solution is supplemented with sulfuric acid and returned to the copper electrolysis system. After electrolysis for a period of time, a copper electrolysis lean solution is obtained and returned to step S1. Among them, the molar ratio of lead carbonate to lead oxide is 1:1, and the molar ratio of the total amount of Pb in lead carbonate and lead oxide to the total amount of As, Bi, and Sb in the primary impurity-removing solution is 2:1. Example 2

[0027] A method for removing impurities from a copper electrolysis lean solution, wherein, The copper electrolysis lean solution comes from the copper electrolysis system, specifically the electrolyte with relatively high impurity content produced by the copper electrolysis system, and the main component content is Cu 2+ with a concentration of 48 g / L, H2SO4 concentration of 200 g / L, As concentration of 3.8 g / L, Bi concentration of 0.44 g / L, and Sb concentration of 0.40 g / L.

[0028] The method steps are as follows: S1 Add 30 wt% hydrogen peroxide and bismuth trioxide to the copper electrolysis lean solution, react at 70 °C for 0.5 h, then perform solid-liquid separation to obtain an oxidized residue and a primary impurity-removing solution. The oxidized residue is returned to the rare metal smelting system for the recovery of arsenic trioxide, antimony trioxide, and bismuth ingots. Among them, the molar ratio of H2O2 in hydrogen peroxide to the total amount of As and Sb in the copper electrolysis lean solution is 2:0.8, the molar ratio of the total amount of Bi in bismuth trioxide to the total amount of As and Sb in the copper electrolysis lean solution is 1.5:1, the As concentration in the primary impurity-removing solution is 0.17 g / L, the Sb concentration is 0.07 g / L, and the Bi concentration is 8.76 g / L; S2 Add lead carbonate and lead oxide to the primary impurity-removing solution obtained in step S1, react at 40 °C for 4.0 h, then obtain a precipitate residue and a secondary impurity-removing solution. The precipitate residue is returned to the lead smelting system for lead recovery, and the secondary impurity-removing solution is supplemented with sulfuric acid and returned to the copper electrolysis system. After electrolysis for a period of time, a copper electrolysis lean solution is obtained and returned to step S1. Among them, the molar ratio of lead carbonate to lead oxide is 5:1, and the molar ratio of the total amount of Pb in lead carbonate and lead oxide to the total amount of As, Bi, and Sb in the primary impurity-removing solution is 5:1. Example 3

[0029] A method for removing impurities from a copper electrolysis lean solution, wherein, The copper electrolysis lean solution comes from the copper electrolysis system, specifically the electrolyte with relatively high impurity content produced by the copper electrolysis system, and the main component content is Cu 2+ with a concentration of 46 g / L, H2SO4 concentration of 190 g / L, As concentration of 4.91 g / L, Bi concentration of 0.41 g / L, and Sb concentration of 0.44 g / L.

[0030] The method steps are as follows: S1: Add hydrogen peroxide with a concentration of 30 wt% and bismuth trioxide to the lean copper electrolysis solution, react at 60 °C for 2.0 h, then perform solid-liquid separation to obtain oxidized slag and the first purified solution. The oxidized slag is returned to the rare metal smelting system to recover arsenic trioxide, antimony trioxide, and bismuth ingots. Among them, the molar ratio of H2O2 in hydrogen peroxide to the total amount of As and Sb in the lean copper electrolysis solution is 2:0.5, the molar ratio of the total amount of Bi in bismuth trioxide to the total amount of As and Sb in the lean copper electrolysis solution is 1.3:1. The concentration of As in the first purified solution is 0.15 g / L, the concentration of Sb is 0.08 g / L, and the concentration of Bi is 5.78 g / L. S2: Add lead carbonate and lead oxide to the first purified solution obtained in step S1, react at 50 °C for 3.0 h, then obtain precipitated slag and the second purified solution. The precipitated slag is returned to the lead smelting system to recover lead, and the second purified solution is supplemented with sulfuric acid and returned to the copper electrolysis system. After electrolysis for a period of time, lean copper electrolysis solution is obtained and returned to step S1. Among them, the molar ratio of lead carbonate to lead oxide is 3:1, and the molar ratio of the total amount of Pb in lead carbonate and lead oxide to the total amount of As, Bi, and Sb in the first purified solution is 3:1. Comparative Example 1

[0031] The specific steps refer to Example 1, with the difference that: in step S2, only lead carbonate is added, and the molar ratio of the total amount of Pb in lead carbonate to the total amount of As, Bi, and Sb in the first purified solution is 2:1. Comparative Example 2

[0032] The specific steps refer to Example 1, with the difference that: in step S2, only lead oxide is added, and the molar ratio of the total amount of Pb in lead oxide to the total amount of As, Bi, and Sb in the first purified solution is 2:1. Test

[0033] Detect the concentrations of As, Bi, and Sb in the second purified solution obtained in steps S2 of Examples 1 to 3 and Comparative Examples 1 to 2. The results are shown in Table 1.

[0034] The concentrations of As, Bi, and Sb in the second purified solution are determined according to the method for chemical analysis of copper concentrate - Part 18: Determination of arsenic, antimony, bismuth, lead, zinc, nickel, cadmium, cobalt, chromium, aluminum oxide, magnesium oxide, and calcium oxide content - Inductively coupled plasma atomic emission spectrometry (GB / T 3884.18 - 2023).

[0035] Table 1 Concentrations of As, Bi, and Sb in the second purified solution Concentration (g / L) Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 As 0.05 0.06 0.08 0.09 0.12 Bi 0.03 0.02 0.03 0.85 1.01 Sb 0.04 0.03 0.04 0.05 0.06 It can be clearly seen from Table 1 that when lead carbonate (Comparative Example 1) or lead oxide (Comparative Example 2) is added alone, the contents of As, Sb, and Bi in the secondary impurity removal solution are higher than those in Examples 1 to 3, indicating that the combined impurity removal effect of lead carbonate and lead oxide is obvious.

[0036] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for removing impurities from copper electrolysis lean solution, characterized in that, It includes the following steps: S1: Add an oxidant and bismuth trioxide to the lean electrolyte of copper electrolysis. After the reaction, solid-liquid separation is carried out to obtain oxidation slag and a primary impurity-removing solution; S2: Add lead carbonate and lead oxide to the primary impurity-removing solution obtained in step S1. After the reaction, precipitate slag and a secondary impurity-removing solution are obtained.

2. The method according to claim 1, wherein In step S1, the molar ratio of the oxidant to the total amount of As and Sb in the lean electrolyte of copper electrolysis is 2:(0.3 - 0.8), and the molar ratio of the total amount of Bi in bismuth trioxide to the total amount of As and Sb in the lean electrolyte of copper electrolysis is (1 - 1.5):

1.

3. The method according to claim 1, characterized in that, In step S1, the reaction temperature is 40 - 70 °C, and the reaction time is 0.5 - 3.0 h.

4. The method according to claim 1, characterized in that, In step S2, the molar ratio of lead carbonate to lead oxide is (1 - 5):

1.

5. The method according to claim 4, wherein In step S2, the molar ratio of the total amount of Pb in lead carbonate and lead oxide to the total amount of As, Bi, and Sb in the primary impurity-removing solution is (2 - 5):

1.

6. The method according to claim 1, wherein In step S2, the reaction temperature is 40 - 70 °C, and the reaction time is 1.0 - 4.0 h.

7. The method according to claim 1, characterized in that, In step S1, the oxidation slag is returned to the rare metal smelting system to recover arsenic, antimony, and bismuth.

8. The method according to claim 1, characterized in that, In step S2, the precipitate slag is returned to the lead smelting system to recover lead.

9. The method according to claim 1, wherein In step S2, sulfuric acid is added to the secondary impurity-removing solution and then it is returned to the copper electrolysis system.

Images