Method for removing impurities from copper electrolysis barren solution

Abstract

The present invention belongs to the field of metallurgy and relates to a method for removing impurities from copper electrolysis lean liquid. The method comprises the following steps: S1: adding an oxidant and bismuth trioxide to the copper electrolysis lean liquid. After the reaction, solid-liquid separation is performed to obtain an oxidation slag and a primary impurity-removing liquid; S2: adding lead carbonate and lead oxide to the primary impurity-removing liquid obtained in step S1. After the reaction, a precipitated slag and a secondary impurity-removing liquid are obtained. The secondary impurity-removing liquid has an As concentration of ≤0.1 g / L, a Bi concentration of ≤0.05 g / L, and a Sb concentration of ≤0.05 g / L. This method can meet the requirement for returning the copper electrolysis lean liquid to electrolysis after impurity removal, while avoiding environmental pollution caused by direct discharge, resulting in significant economic and environmental benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy, and in particular relates to a method for removing impurities from copper electrolysis barren liquid. Background Art

[0002] Copper anode plates cast using copper fire refining typically contain approximately 0.50% impurities. These impurities, due to their varying electrochemical properties, migrate in different directions during the electrolytic refining process, thus impacting the electrolytic process in varying ways. The core goal of electrolytic refining is to maximize the deposition of copper at the cathode while concentrating the impurity elements primarily in the anode mud. The primary impurity elements in copper anode plates, with potentials close to that of copper, include arsenic (As), antimony (Sb), and bismuth (Bi). These elements can either electrochemically dissolve with copper at the anode or precipitate with copper ions at the cathode during the electrolysis process, significantly affecting the quality of the cathode copper.

[0003] Electrodeposition is the core purification technology for traditional copper electrolysis barren liquor. This method leverages the differences in precipitation potentials of copper ions at varying concentrations to achieve purification and impurity removal. As the electrolysis process continues, once the copper ion concentration drops to a certain threshold, impurity ions precipitate at the cathode, forming so-called black copper sludge. Typically, this black copper sludge is recycled back into the pyrometallurgical system for further processing. However, the large amounts of harmful impurities contained in this black copper sludge, such as arsenic (As), antimony (Sb), and bismuth (Bi), gradually accumulate in the pyrometallurgical system, ultimately affecting product quality. To avoid the generation of large amounts of black copper sludge, researchers have begun exploring new purification methods, such as precipitation, to remove impurity ions from the electrolyte. Although precipitation methods are simple to operate, they face challenges, including complex precipitant preparation, limited impurity removal effectiveness, high production costs, and the large amount of precipitate required for subsequent processing and recycling. Furthermore, some precipitation methods may introduce new impurities, which collectively limit their application in industrial electrolyte purification. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for removing impurities from copper electrolysis barren solution.

[0005] The specific technical solutions are as follows:

[0006] A method for removing impurities from copper electrolysis barren solution comprises the following steps:

[0007] S1: adding oxidant and bismuth trioxide to the copper electrolysis lean solution. After the reaction, solid-liquid separation is performed to obtain oxide slag and primary impurity removal liquid.

[0008] S2: adding lead carbonate and lead oxide to the primary impurity removal liquid obtained in step S1, and after reaction, obtaining precipitated residue and secondary impurity removal liquid.

[0009] Wherein, the copper electrolysis lean solution comes from the copper electrolysis system.

[0010] Specifically, the main component content of the copper electrolysis barren solution is: Cu 2+ The concentration is 45~48g / L, the H2SO4 concentration is 180~200g / L, the As concentration is ≤5.0g / L, the Bi concentration is ≤0.5g / L, and the Sb concentration is ≤0.5g / L.

[0011] The reaction mechanism of the present invention is as follows:

[0012] The present invention adds an oxidant and bismuth trioxide to the copper electrolysis barren solution to achieve the AsO3 3- and SbO3 3- The As, Sb and Bi in the solution are selectively removed by oxidation and removal of lead carbonate and lead oxide.

[0013] In step S1, bismuth trioxide reacts with sulfuric acid to generate Bi 3+ At the same time, the oxidant converts AsO3 in the copper electrolysis lean solution 3- and SbO3 3- Oxidized to AsO4 3- and SbO4 3- , AsO4 3- and SbO4 3- With Bi in solution 3+ The reactions generate BiAsO4 and BiSbO4 precipitates respectively. The oxidant is preferably H2O2 (hydrogen peroxide). The main reactions are:

[0014] H3AsO3+H2O2=H3AsO4+H2O;

[0015] H3SbO3+H2O2=H3SbO4+H2O;

[0016] Bi2O3+3H2SO4=Bi2(SO4)3+3H2O;

[0017] 2H3AsO4+Bi2(SO4)3=2BiAsO4↓+3H2SO4;

[0018] 2H3SbO4+Bi2(SO4)3=2BiSbO4↓+3H2SO4.

[0019] Among them, the As concentration in the primary impurity removal liquid is ≤0.2g / L, the Sb concentration is ≤0.1g / L, and the Bi concentration is ≤8.8g / L.

[0020] Furthermore, in step S1, the molar ratio of the oxidant to the total amount of As and Sb in the copper electrolysis barren solution 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 copper electrolysis barren solution is (1~1.5):1.

[0021] Furthermore, in step S1, the reaction temperature is 40-70° C., and the reaction time is 0.5-3.0 h.

[0022] Preferably, in step S1, the oxide slag is returned to the rare metal smelting system to recover arsenic, antimony and bismuth.

[0023] 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, which can selectively remove As, Sb, and Bi from the solution. The main reactions are:

[0024] PbCO3+H2SO4=PbSO4↓+H2O+CO2↑;

[0025] PbO+H2SO4=PbSO4↓+H2O.

[0026] Due to different raw materials and reaction mechanisms, the physical adsorption properties of the resulting lead sulfate (such as specific surface area, porosity, and particle morphology) vary significantly. Lead oxide reacts rapidly with sulfuric acid, releasing significant heat and producing irregular, dense blocks or larger particles with minimal internal pores. Lead carbonate reacts more slowly with sulfuric acid, forming either regular crystal morphologies or flocculent, porous structures. The vigorous and highly exothermic reaction of lead oxide provides an initial high supersaturation, facilitating extensive nucleation and the formation of fine crystal nuclei. Lead carbonate reacts more slowly, releasing carbon dioxide, which helps maintain and prolong moderate supersaturation, promoting sustained and controlled nucleation growth and suppressing the intense hard agglomeration caused by transient high supersaturation and heat. A mixture of the two more easily produces particles with a relatively small, more uniform particle size and significantly reduced agglomeration, which improves the adsorption performance of lead sulfate.

[0027] Among them, in the secondary impurity removal liquid, the As concentration is ≤0.1g / L, the Bi concentration is ≤0.05g / L, and the Sb concentration is ≤0.05g / L.

[0028] Furthermore, in step S2, the molar ratio of lead carbonate to lead oxide is (1-5):1.

[0029] 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 liquid is (2-5):1.

[0030] Furthermore, in step S2, the reaction temperature is 40-70° C., and the reaction time is 1.0-4.0 h.

[0031] Preferably, in step S2, the precipitated slag is returned to the lead smelting system to recover the lead.

[0032] Preferably, in step S2, sulfuric acid is added to the secondary impurity removal liquid and returned to the copper electrolysis system. After electrolysis, the concentration of impurities such as arsenic, antimony, and bismuth in the electrolyte increases significantly. The purified portion of the electrolyte becomes the copper electrolysis lean solution, which can be returned to step S1.

[0033] The beneficial effects of the present invention are as follows:

[0034] The present invention first uses an oxidant and bismuth trioxide to remove As and Sb in the copper electrolysis lean solution, and then uses lead carbonate and lead oxide to further selectively remove As, Sb and Bi, so that the As concentration in the secondary impurity removal liquid is ≤0.1 g / L, the Bi concentration is ≤0.05 g / L, and the Sb concentration is ≤0.05 g / L. The demand for returning the copper electrolysis lean solution to electrolysis after impurity removal can be met, while avoiding environmental pollution caused by direct discharge, and achieving significant economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a process flow chart of the method for removing impurities from copper electrolysis barren solution in a specific implementation manner. DETAILED DESCRIPTION

[0036] The principles and features of the present invention are described below with reference to examples. The examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial sources. Example 1

[0037] A method for removing impurities from copper electrolytic barren solution, wherein:

[0038] 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 of which is Cu 2+ The concentration is 45g / L, the H2SO4 concentration is 180g / L, the As concentration is 4.2g / L, the Bi concentration is 0.48g / L, and the Sb concentration is 0.42g / L.

[0039] The steps are as follows:

[0040] S1: Add 30wt% hydrogen peroxide and bismuth trioxide to the copper electrolysis lean solution, react at 40°C for 3.0h, and separate the solid and liquid to obtain oxide slag and a primary impurity removal liquid. The oxide slag is returned to the scattered metal smelting system to recover arsenic trioxide, antimony trioxide, and bismuth ingots. The molar ratio of H2O2 in the 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 the bismuth trioxide to the total amount of As and Sb in the copper electrolysis lean solution is 1:1, and the As concentration in the primary impurity removal liquid is 0.18g / L, the Sb concentration is 0.08g / L, and the Bi concentration is 1.33g / L.

[0041] S2: Add lead carbonate and lead oxide to the primary impurity removal liquid obtained in step S1, react at 70°C for 1.0h, and obtain a precipitate residue and a secondary impurity removal liquid. The precipitate residue is returned to the lead smelting system to recover lead, and sulfuric acid is added to the secondary impurity removal liquid and returned to the copper electrolysis system. After electrolysis for a period of time, a copper electrolysis lean solution is obtained, and the copper electrolysis lean solution is returned to step S1; wherein the molar ratio of lead carbonate to lead oxide is 1:1, and the molar ratio of the total amount of Pb in the lead carbonate and lead oxide to the total amount of As, Bi, and Sb in the primary impurity removal liquid is 2:1. Example 2

[0042] A method for removing impurities from copper electrolytic barren solution, wherein:

[0043] 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 of which is Cu 2+ The concentration is 48g / L, the H2SO4 concentration is 200g / L, the As concentration is 3.8g / L, the Bi concentration is 0.44g / L, and the Sb concentration is 0.40g / L.

[0044] The steps are as follows:

[0045] S1: Add 30wt% hydrogen peroxide and bismuth trioxide to the copper electrolysis lean solution, react at 70°C for 0.5h, and separate the solid and liquid to obtain oxide slag and a primary impurity removal liquid. The oxide slag is returned to the scattered metal smelting system to recover arsenic trioxide, antimony trioxide, and bismuth ingots. The molar ratio of H2O2 in the 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 the bismuth trioxide to the total amount of As and Sb in the copper electrolysis lean solution is 1.5:1, and the As concentration in the primary impurity removal liquid is 0.17g / L, the Sb concentration is 0.07g / L, and the Bi concentration is 8.76g / L.

[0046] S2: Add lead carbonate and lead oxide to the primary impurity removal liquid obtained in step S1, react at 40°C for 4.0 hours, and obtain a precipitate residue and a secondary impurity removal liquid. The precipitate residue is returned to the lead smelting system to recover lead, and sulfuric acid is added to the secondary impurity removal liquid and returned to the copper electrolysis system. After electrolysis for a period of time, a copper electrolysis lean solution is obtained, and the copper electrolysis lean solution is returned to step S1; wherein the molar ratio of lead carbonate to lead oxide is 5:1, and the molar ratio of the total amount of Pb in the lead carbonate and lead oxide to the total amount of As, Bi, and Sb in the primary impurity removal liquid is 5:1. Example 3

[0047] A method for removing impurities from copper electrolytic barren solution, wherein:

[0048] 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 of which is Cu 2+ The concentration is 46g / L, the H2SO4 concentration is 190g / L, the As concentration is 4.91g / L, the Bi concentration is 0.41g / L, and the Sb concentration is 0.44g / L.

[0049] The steps are as follows:

[0050] S1: Add 30wt% hydrogen peroxide and bismuth trioxide to the copper electrolysis lean solution, react at 60°C for 2.0h, and separate the solid and liquid to obtain oxide slag and a primary impurity removal liquid. The oxide slag is returned to the scattered metal smelting system to recover arsenic trioxide, antimony trioxide, and bismuth ingots. The molar ratio of H2O2 in the hydrogen peroxide to the total amount of As and Sb in the copper electrolysis lean solution is 2:0.5, the molar ratio of the total amount of Bi in the bismuth trioxide to the total amount of As and Sb in the copper electrolysis lean solution is 1.3:1, and the As concentration in the primary impurity removal liquid is 0.15g / L, the Sb concentration is 0.08g / L, and the Bi concentration is 5.78g / L.

[0051] S2: Add lead carbonate and lead oxide to the primary impurity removal liquid obtained in step S1, react at 50°C for 3.0 hours, and obtain a precipitate residue and a secondary impurity removal liquid. The precipitate residue is returned to the lead smelting system to recover lead, and sulfuric acid is added to the secondary impurity removal liquid and returned to the copper electrolysis system. After electrolysis for a period of time, a copper electrolysis lean solution is obtained, and the copper electrolysis lean solution is returned to step S1; wherein the molar ratio of lead carbonate to lead oxide is 3:1, and the molar ratio of the total amount of Pb in the lead carbonate and lead oxide to the total amount of As, Bi, and Sb in the primary impurity removal liquid is 3:1. Comparative Example 1

[0052] The specific steps are as in Example 1, except that: in step S2, only lead carbonate is added, and the molar ratio of the total amount of Pb in the lead carbonate to the total amount of As, Bi, and Sb in the primary impurity removal liquid is 2:1. Comparative Example 2

[0053] The specific steps are as in Example 1, except that: in step S2, only lead oxide is added, and the molar ratio of the total amount of Pb in the lead oxide to the total amount of As, Bi, and Sb in the primary impurity removal solution is 2:1.

[0054] test

[0055] The concentrations of As, Bi, and Sb in the secondary impurity removal liquids obtained in step S2 of Examples 1 to 3 and Comparative Examples 1 to 2 were detected, and the results are shown in Table 1.

[0056] The concentrations of As, Bi and Sb in the secondary impurity removal liquid are determined in accordance with the chemical analysis method 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).

[0057] Table 1 As, Bi, and Sb concentrations in the secondary impurity removal solution

[0058] 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

[0059] 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 As, Sb, and Bi contents in the secondary impurity removal liquid are all higher than those in Examples 1 to 3, indicating that the mixed impurity removal effect of lead carbonate and lead oxide is obvious.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for removing impurities from copper electrolysis barren solution, characterized in that: The steps include: S1: adding oxidant and bismuth trioxide to the copper electrolysis lean solution. After the reaction, solid-liquid separation is performed to obtain oxide slag and primary impurity removal liquid. S2: adding lead carbonate and lead oxide to the primary impurity removal liquid obtained in step S1, and reacting to obtain precipitated residue and secondary impurity removal liquid; In step S2, the molar ratio of lead carbonate to lead oxide is (1-5):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 removal liquid is (2-5):

1.

2. The method according to claim 1, characterized in that In step S1, the molar ratio of the oxidant to the total amount of As and Sb in the copper electrolysis lean solution 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 copper electrolysis lean solution 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, wherein In step S2, the reaction temperature is 40-70° C., and the reaction time is 1.0-4.0 h.

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

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

7. The method according to claim 1, characterized in that In step S2, sulfuric acid is added to the secondary impurity removal liquid and returned to the copper electrolysis system.

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