Method for recovering copper from zinc sulfate solution
By combining the decoppering and purification processes in zinc hydrometallurgy and repeatedly utilizing by-products, the problem of low copper recovery rate in pyrometallurgy is solved, efficient copper and zinc recovery is achieved, and energy consumption and costs are reduced.
Patent Information
- Application Number
- CN202480014187.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-11-21
- Filing Date
- 2024-05-22
- Publication Date
- 2025-09-19
AI Technical Summary
The existing pyrometallurgical process has a low copper recovery rate and high energy consumption. Traditional methods require a large amount of fossil fuels, and the copper recovery rate in the zinc hydrometallurgical process is insufficient.
The by-products generated during the purification process are combined with the copper removal process in the zinc hydrometallurgical process. By repeatedly introducing the existing zinc hydrometallurgical process multiple times and combining weak acid leaching, adjustment, repulping and purification leaching processes, copper in the zinc sulfate solution is recovered, avoiding a separate refining process and improving the recovery rate of copper and zinc.
A copper recovery rate of over 90% was achieved, reducing copper refining costs, and increasing zinc recovery, reducing energy consumption and fossil fuel use.
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Figure CN120677257A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a method for recovering copper contained in a zinc sulfate solution. Background Art
[0002] The zinc refining process typically involves roasting zinc concentrate in the form of sphalerite oxide (ZnS), leaching the resulting calcined product (ZnO) by dissolving it in sulfuric acid, performing a multi-stage purification process to remove impurities, and then electrolyzing the resulting pure zinc sulfate solution to produce zinc precipitate at the cathode. During the leaching process, various metal components contained in the zinc concentrate, such as iron (Fe), copper (Cu), nickel (Ni), cobalt (Co), and cadmium (Cd), are also leached. Among these leached metal components, copper is particularly removed as copper cement through a copper removal process. This copper cement can be recovered as pure copper through copper refining.
[0003] Typically, copper is recovered during zinc refining through pyrometallurgical purification of by-products produced during the process. However, the copper recovery rate of the pyrometallurgical process is limited to approximately 50% to 70%, and the copper grade of the slag produced through the pyrometallurgical process is between 0.3% and 0.5%, resulting in low recovery of valuable metals.
[0004] In addition, traditional pyrometallurgical methods require a lot of energy and use a lot of fossil fuels. Summary of the Invention
[0005] Technical issues
[0006] The present invention provides a method for recovering copper contained in a zinc sulfate solution, wherein byproducts generated during a purification process are connected to a copper removal process in an existing zinc hydrometallurgical process, thereby recovering more than 90% of the dissolved copper in the raw material during the zinc hydrometallurgical process.
[0007] A method for recovering copper contained in a zinc sulfate solution is also provided, wherein the copper recovery is carried out in conjunction with a copper removal process in an existing zinc hydrometallurgical process without requiring a separate refining process, thereby minimizing refining costs.
[0008] In addition, a method for recovering copper contained in zinc sulfate solution is provided, wherein the by-products generated during the purification process are connected to a conventional zinc hydrometallurgical process to additionally recover the zinc contained in the by-products, thereby improving the zinc recovery rate in the hydrometallurgical zinc refining process.
[0009] Technical Solution
[0010] According to one embodiment of the present invention, a method for recovering copper from a zinc sulfate solution produced by a leaching process in which zinc ore is dissolved in sulfuric acid, the method comprising: a neutral leaching process for dissolving the zinc ore; a weak acid leaching process for dissolving a neutral leaching solution, wherein the zinc ore is dissolved with sulfuric acid to produce a zinc sulfate solution; a decoppering process for removing copper dissolved in the zinc sulfate solution in the form of copper cement; a conditioning process for reducing the decoppering solution discharged from the decoppering process; a repulping process for repulping a conditioning cake with zinc solution, the conditioning cake being a solid discharged from the conditioning process; and a purification leaching process for dissolving copper contained in the repulping solution discharged from the repulping process by sulfuric acid dissolution, wherein the purification leaching solution discharged from the purification leaching process is neutralized by adding zinc calcined material and then reintroduced into the weak acid leaching process.
[0011] The zinc sulfate solution is then introduced into the weak acid leaching process and further directed to the copper removal process.
[0012] The conditioning process includes reducing the copper removal solution to generate a conditioned solution, and treating the conditioned solution in a concentrator and a filter to discharge the solution as an input solution for the iron precipitation process and the solids as a conditioned cake.
[0013] The iron precipitation process input solution is introduced into the iron precipitation process for recovering iron oxides by a pressure oxidation process.
[0014] The iron precipitation process includes: generating an iron precipitation process solution through a pressure oxidation process; and treating the iron precipitation process solution in a concentrator and a filter to discharge the solution to be transferred to a neutral leaching process and solids as iron oxides.
[0015] The repulping process is carried out at a process temperature of 60°C to 80°C and a pH of 2.5 to 3.0.
[0016] The zinc solution in the repulping process contains a conditioning cake at a concentration of 100 g / L to 200 g / L.
[0017] The solution after the purification leaching process contains sulfuric acid at a concentration of 25 g / L to 50 g / L.
[0018] More than 85% of the copper contained in the conditioning cake is dissolved through the purification leaching process.
[0019] The iron and zinc contained in the conditioning cake are dissolved to over 92% and over 98% respectively through the purification leaching process.
[0020] The purification leaching process is carried out at a dissolution temperature of 60°C to 80°C and a process pressure of 1 to 2 atmospheres for 2 to 3 hours.
[0021] The weak acid leaching process is carried out at pH 2.5 to 3.0.
[0022] The weak acid leaching process is carried out for 3 to 4 hours.
[0023] Beneficial effects
[0024] According to the present disclosure, by-products generated during the purification process are repeatedly introduced into the existing zinc hydrometallurgical process to recover copper dissolved in the hydrometallurgical raw materials with a maximum yield.
[0025] Furthermore, the cost required for the copper refining process can be minimized by integrating copper recovery with the existing zinc refining process rather than requiring a separate refining process.
[0026] In addition, the recovery rate of zinc can be improved by reintroducing zinc contained in by-products produced during the purification process into the zinc hydrometallurgical process. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 is a process flow diagram for copper recovery according to an embodiment of the present disclosure.
[0028] Figure 2 The invention is a process flow chart specifically illustrating a reslurrying process, a purification leaching process, and a neutralization process in a method for recovering copper from a zinc sulfate solution according to an embodiment of the present invention. DETAILED DESCRIPTION
[0029] In a typical zinc refining process, zinc material is leached in sulfuric acid, which also leaches iron (Fe), copper (Cu), and other elements. The copper contained in the leachate is then separated in a solid-liquid separation process, and a strong reducing agent such as zinc powder is added to reduce the dissolved copper (Cu) in the form of copper sulfate (CuSO4) to copper cement, which is removed as a precipitate. In addition, a large amount of iron dissolves in the zinc sulfate solution and is removed during the iron precipitation process (Fe precipitation).
[0030] Aiming to maximize the recovery of dissolved copper in materials targeted by the zinc refining process, the present disclosure can recover over 90% of the copper ions contained in the leachate produced during the zinc refining process.
[0031] Figure 1 is a process flow diagram for copper recovery according to an embodiment of the present disclosure.
[0032] refer to Figure 1The zinc refining process involves leaching zinc-containing raw materials, such as zinc concentrate, calcined material obtained by roasting zinc concentrate, or zinc ferrite, in sulfuric acid at atmospheric pressure to produce a zinc sulfate solution. The calcined material is then used to neutralize the sulfuric acid remaining from the leaching process to primarily remove impurities (neutral leaching process (S1)). Copper components leached with the raw materials during leaching do not precipitate during the neutralization process and therefore remain in the process solution after neutralization.
[0033] The solution obtained after the dissolution and neutralization of the zinc-containing raw material, i.e., the post-neutralization leaching solution, is redissolved in sulfuric acid to produce a zinc sulfate solution (weak acid leaching process (S2)). The pH used in the weak acid leaching process (S2) can be in the range of approximately 2.5 to 3.0, and the process can be carried out in a concentrator. The residence time of the zinc sulfate solution in the weak acid leaching process (S2) is approximately 3 to 4 hours, and the process temperature can be approximately 65°C.
[0034] The zinc sulfate solution discharged from the weak acid leaching process (S2) contains a large amount of dissolved copper. By adding a strong reducing agent such as zinc (Zn) powder to the zinc sulfate solution, the dissolved copper (Cu) in the form of copper sulfate (CuSO4) is reduced and precipitated as copper cement, i.e., metallic copper powder, for removal (copper removal process (S3)). The copper cement can be recovered as pure copper through copper refining.
[0035] The post-copper removal solution discharged from the copper removal process (S3) is introduced into the conditioning process (S4). In the conditioning process (S4), the post-copper removal solution is fed into a conditioning tank, passed through a concentrator and filter, and a post-conditioning solution is obtained, while the solid residue is discharged as a conditioning cake. The post-conditioning solution, which serves as the input solution for the iron precipitation process, is then introduced into the iron precipitation process (S5), where iron oxides are recovered through a pressurized oxidation process. In the iron precipitation process (S5), the iron precipitation process input solution is introduced into an iron precipitation tank, passed through a concentrator and filter, and a post-iron precipitation solution is obtained, while the solid residue in the form of iron oxides is discharged. The post-iron precipitation solution is transferred back to the neutral leaching process (S1). Since copper and iron are discharged as copper cement and iron oxides, respectively, during the copper removal process (S3) and iron precipitation process (S5), the post-iron precipitation solution is considered a pure zinc sulfate solution with a high zinc content. This zinc sulfate solution is then transferred to a process where zinc is collected by electrolysis and precipitated at the cathode.
[0036] The conditioning cake discharged from the conditioning process (S4) still contains valuable metals such as copper, iron, and zinc. In order to recover these metals contained in the conditioning cake, it is necessary to dissolve the copper, iron, zinc, etc. contained in the conditioning cake and transfer them back to the copper removal process, iron precipitation process, electrolysis process, etc.
[0037] To this end, the conditioned cake discharged from the conditioning process (S4) is re-pulped in a zinc solution at a temperature of about 60° C. to 80° C. for about 1.5 hours (re-pulping process (S6)). The re-pulping process (S6) may be performed at a pH range of about 2.5 to 3.0, and the concentration of the conditioned cake in the zinc solution during the re-pulping process (S6) may be about 100 g / L to 200 g / L.
[0038] The post-repulping solution discharged from the repulping process ( S6 ) is dissolved in sulfuric acid to dissolve most of the copper contained in the post-repulping solution (purification leaching process ( S7 )). The concentration of sulfuric acid used here can be approximately 25 g / L to 50 g / L. The purification leaching process ( S7 ) is performed for approximately 2 to 3 hours at a dissolution temperature of approximately 60°C to 80°C and a process pressure of approximately 1 to 2 atmospheres. Through the purification leaching process ( S7 ), over 85% of the copper contained in the conditioned cake can be dissolved. Furthermore, in the purification leaching process ( S7 ), not only copper but also iron, zinc, and other metals contained in the conditioned cake are leached. Specifically, during the purification leaching process ( S7 ), over 92% of the iron contained in the conditioned cake is dissolved, and over 98% of the zinc is dissolved.
[0039] The purified leaching solution discharged from the purification leaching process (S7) is subjected to a process (neutralization process (S8)) of introducing zinc calcined material to neutralize the purified leaching solution before being reintroduced into the weak acid leaching process (S2). The purified leaching solution introduced into the weak acid leaching process (S2) is dissolved in sulfuric acid together with the neutral leaching solution discharged from the neutral leaching process (S1) to form a zinc sulfate solution, which is then introduced into the copper removal process (S3).
[0040] In the purification leaching process (S7), a large amount of copper, iron, zinc, and other metals contained in the conditioning cake, a by-product of the conditioning process (S4), are dissolved. The solution is then reintroduced into the weak acid leaching process (S2) during the zinc refining process, allowing the recovery of valuable metals, particularly copper, that would otherwise be discarded with the conditioning cake. This maximizes the recovery of dissolved copper from the hydrometallurgical feedstock used for zinc refining. Zinc recovery can also be improved by reintroducing zinc from the by-product back into the zinc refining process. Furthermore, copper recovery can be achieved by integrating it with the pre-existing zinc refining process, eliminating the need for a separate copper refining process, thereby minimizing the costs required for copper refining.
[0041] Figure 2 It is a process flow chart specifically illustrating a repulping process ( S6 ), a purification leaching process ( S7 ), and a neutralization process ( S8 ) in a method for recovering copper from a zinc sulfate solution according to an embodiment of the present disclosure.
[0042] refer to Figure 2The conditioning cake discharged from the conditioning process (S4) was introduced into the reslurry tank (10) together with the zinc solution. The amount of the conditioning cake introduced into the reslurry tank (10) was 120 T / D (tons / day), and the metal composition contained in the conditioning cake was measured.
[0043] Table 1
[0044] Adjust the ratio of copper (Cu), iron (Fe), zinc (Zn), arsenic (As) and lead (Pb) in the cake
[0045]
[0046] The reslurrying process in the reslurrying tank (10) was carried out at 60°C for 1.5 hours, and the concentration of the adjusted cake in the solution introduced into the reslurrying process was measured to be 143 g / L. Next, the post-repulping solution discharged from the reslurrying process was introduced into the purification leaching process reactor (20), and the concentration of the repulped pulp contained in the post-repulping solution was measured.
[0047] Table 2
[0048] Concentrations of copper (Cu), iron (Fe), zinc (Zn), arsenic (As), and lead (Pb) in the solution after the repulping process
[0049]
[0050] The repulping solution was introduced into the purification leaching process reactor (20) along with the zinc sulfate solution. The sulfuric acid concentration in the zinc sulfate solution was measured to be 85 g / L. The concentrations of copper, iron, zinc, and arsenic in the zinc sulfate solution introduced into the purification leaching process reactor (20) were measured.
[0051] Table 3
[0052] Concentrations of copper (Cu), iron (Fe), zinc (Zn), and arsenic (As) in the zinc sulfate solution introduced into the purification leaching process
[0053]
[0054] The repulped solution and zinc sulfate solution introduced into the purification leaching process reactor (20) were reacted at 65°C for 2 hours, during which time most of the copper was dissolved. The concentrations and dissolution rates of copper (Cu), iron (Fe), zinc (Zn), arsenic (As), and lead (Pb) in the purification leaching process solution discharged from the purification leaching process were measured. At this time, the final acidity of sulfuric acid (H2SO4) in the purification leaching process solution was measured to be 35 g / L.
[0055] Table 4
[0056] Concentrations of copper (Cu), iron (Fe), zinc (Zn), arsenic (As), and lead (Pb) in the solution after the purification leaching process
[0057]
[0058] Referring to Table 4, it was observed that the purified leaching solution discharged from the purification leaching process contained copper with a solubility greater than 75%, iron with a solubility greater than 87%, and zinc with a solubility greater than 97%. That is, most of the valuable metals (copper, zinc, and iron) contained in the conditioning cake were dissolved and present in the zinc sulfate solution in the form of ions while undergoing the repulping and purification leaching processes. Then, after adding the zinc calcined material, the purified leaching solution was introduced into the Fumer NT (30). The purified leaching solution was neutralized by adding the zinc calcined material to the Fumer NT (30). The composition of the zinc calcined material introduced into the purified leaching solution is shown in Table 5 below.
[0059] Table 5
[0060] Composition of the zinc calcined solution introduced into the purification leaching process
[0061]
[0062] In the Fumer NT (30), the purified post-leaching solution is reacted at 65°C for 1 hour by adding zinc calcined material and has a final acidity of pH 2.5. The post-neutralization solution discharged from the neutralization process in the Fumer NT (30) passes through a concentrator (40), in which the solid is transferred out, and the post-neutralization solution in liquid form is transferred to a precipitation tank (50) of the weak acid leaching process for reintroduction into the weak acid leaching process. The metallic copper (Cu), iron (Fe) and zinc (Zn) contained in the reintroduced solution can be recovered through a copper removal process, an iron precipitation process and an electrolysis process and in combination with a copper removal process, an adjustment process, an iron precipitation process, an electrolysis process, etc. In addition, the purified post-leaching solution reintroduced into the weak acid leaching process can be passed through an adjustment process, a re-slurry process and a purified leaching process again together with a newly introduced zinc sulfate solution, thereby enabling the recovery of copper (Cu), iron (Fe) and zinc (Zn) that were not recovered in the initial cycle. Therefore, the by-product discharged in the form of the conditioning cake can undergo these processes multiple times, and as these processes are repeated, the recovery rates of copper (Cu), iron (Fe), and zinc (Zn) are expected to increase continuously.
[0063] The technical concepts of the present disclosure have been described herein with reference to certain embodiments and examples illustrated in the accompanying drawings. However, it should be understood that various substitutions, modifications, and variations are possible without departing from the technical concept and scope of the present disclosure, as would be understood by those skilled in the art. Furthermore, it should be understood that such substitutions, modifications, and variations are within the scope of the appended claims.
Claims
1. A method for recovering copper from a zinc sulfate solution produced by a leaching process in which zinc ore is dissolved in sulfuric acid, the method comprising: a neutral leaching process for dissolving the zinc ore; a weak acid leaching process for dissolving the solution after the neutral leaching process, wherein the zinc ore is dissolved with sulfuric acid to produce a zinc sulfate solution; a decoppering process for removing the copper dissolved in the zinc sulfate solution in the form of copper cement; a conditioning process for reducing a post-copper removal solution discharged from the copper removal process; a reslurrying process for reslurrying a conditioning cake with a zinc solution, the conditioning cake being a solid discharged from the conditioning process; as well as a purification leaching process for dissolving the copper contained in the post-repulping solution discharged from the repulping process by sulfuric acid dissolution, The post-purification leaching process solution discharged from the purification leaching process is neutralized by adding zinc calcined material and then introduced into the weak acid leaching process.
2. The method according to claim 1, wherein the zinc sulfate solution reintroduced into the weak acid leaching process is further directed to the copper removal process.
3. The method according to claim 1, wherein the adjusting process comprises: reducing the copper removal solution to generate a conditioning solution; as well as The conditioned solution is processed in a concentrator and filter to remove the solution as the input solution to the iron precipitation process and the solids as the conditioned cake.
4. The method of claim 3, wherein the iron precipitation process input solution is introduced into an iron precipitation process for recovery of iron oxides by a pressure oxidation process.
5. The method of claim 4, wherein the iron precipitation process comprises: generating a solution after the iron precipitation process through the pressure oxidation process; as well as The post-iron precipitation process solution is processed in a concentrator and filter to discharge the solution to be transferred to the neutral leaching process and the solids as iron oxides. 6 . The method of claim 1 , wherein the repulping process is performed at a process temperature of 60° C. to 80° C. and a pH of 2.5 to 3.
0.
7. The method according to claim 6, wherein the zinc solution in the repulping process contains a conditioning cake having a concentration of 100 g / L to 200 g / L.
8. The method according to claim 1, wherein the purified leaching solution contains sulfuric acid at a concentration of 25 g / L to 50 g / L.
9. The method of claim 8, wherein more than 85% of the copper contained in the conditioning cake is dissolved by the purification leaching process.
10. The method according to claim 9, wherein the iron and zinc contained in the conditioned cake are dissolved by more than 92% and more than 98%, respectively, through the purification leaching process.
11. The method of claim 8, wherein the purification leaching process is performed at a dissolution temperature of 60 to 80°C and a process pressure of 1 to 2 atmospheres for 2 to 3 hours.
12. The method of claim 1, wherein the weak acid leaching process is performed at a pH of 2.5 to 3.
0.
13. The method according to claim 12, wherein the weak acid leaching process is carried out for 3 to 4 hours.