COPPER RECOVERY METHOD
Patent Information
- Authority / Receiving Office
- VN · VN
- Patent Type
- Applications
- Current Assignee / Owner
- KOREA ZINC CO LTD
- Filing Date
- 2024-05-03
- Publication Date
- 2026-06-15
AI Technical Summary
Current copper recovery processes face inefficiencies due to high iron concentrations in the electrolyte, which reduce current efficiency and require additional impurity removal steps, especially in atmospheric leaching where iron is leached alongside copper.
A pressure leaching process is employed, where raw materials containing copper are pressurized in a copper electrolyte solution with controlled sulfuric acid concentration and temperature, effectively leaching copper while precipitating iron as iron oxide, thereby reducing iron concentration in the electrolyte.
This approach maintains a high copper leaching rate while achieving an iron precipitation rate of 84% or more, thereby improving the current efficiency of the electrolytic process for copper recovery and reducing the need for additional impurity removal steps.
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Figure VN1202603190_0
Abstract
Description
How to recover copper
[0001] The present invention relates to a method for reducing the concentration of iron in an electrolyte for copper recovery by pressurizing a raw material containing copper into a copper electrolyte solution containing copper and sulfuric acid, thereby leaching out copper in the raw material and precipitating and removing iron.
[0002] The process for recovering pure copper from copper-containing raw materials typically involves leaching the raw material in a sulfuric acid solution at atmospheric pressure or under pressure. For atmospheric leaching, the reaction time must exceed 16 hours to maximize copper extraction efficiency. This increased oxygen and steam consumption increases the cost of copper recovery and reduces recovery efficiency.
[0003] In addition, raw materials containing copper contain not only copper but also components such as iron. In the case of atmospheric leaching, iron components other than copper are leached together, which causes an increase in the iron concentration in the electrolyte of the electrolytic process, which is the subsequent process of the leaching process. If the iron concentration in the electrolyte is high, it causes corrosion of the zinc deposited on the cathode of the electrolytic process, which reduces the hydrogen overvoltage, and the Fe contained in the sulfuric acid solution at the cathode and anode 2+ , Fe 3+ The current efficiency is reduced by the redox reaction of ions, and additional processes are required to remove impurities.
[0004] In a method for recovering copper, a method is provided for increasing the precipitation rate of iron while maintaining a high leaching rate of copper contained in a solution by controlling the reaction temperature, pressure, and post-reaction sulfuric acid concentration conditions of a pressure leaching process.
[0005] In addition, in a method for recovering copper, a method is provided for improving the current efficiency of an electrolytic process by lowering the iron concentration in an electrolyte solution introduced into the electrolytic process.
[0006] A method for recovering copper according to one embodiment of the present invention includes a pressure leaching process in which a raw material containing copper is pressurized into a copper electrolytic solution containing copper and sulfuric acid, so that copper contained in the raw material is leached and iron contained in the raw material is precipitated in the form of iron oxide, and an electrolytic process in which a pressure leaching process effluent discharged from the pressure leaching process is electrolyzed to deposit copper at a cathode and recover it, wherein the concentration of sulfuric acid in the pressure leaching process effluent is 20 g / L to 40 g / L, and the reaction temperature of the pressure leaching process is 150°C to 200°C.
[0007] In the above pressure leaching process, the precipitation rate of iron may be 84% or more, and in the above pressure leaching process, the leaching rate of copper may be 83% or more.
[0008] A method for recovering copper according to another embodiment of the present invention comprises a pressure leaching process in which a raw material containing copper is pressurized into a copper electrolytic solution containing copper and sulfuric acid, so that copper contained in the raw material is leached and iron contained in the raw material is precipitated in the form of iron oxide, and an electrolytic process in which a pressure leaching process effluent discharged from the pressure leaching process is electrolyzed to deposit copper at a cathode and recover it, wherein the concentration of sulfuric acid in the pressure leaching process effluent is 20 g / L to 60 g / L, and the reaction temperature of the pressure leaching process is 180°C to 200°C.
[0009] In the above pressure leaching process, the precipitation rate of iron may be 84% or more, and in the above pressure leaching process, the leaching rate of copper may be 91% or more.
[0010] The above pressure leaching process can use an autoclave.
[0011] The internal pressure of the above autoclave may be 900 kPa or more and 2,000 kPa or less.
[0012] The above pressurized leaching process can be performed by injecting oxygen into the autoclave.
[0013] The liquid after the above pressurized leaching process is treated in a coolant and a filter, and the discharged solution is transferred to the electrolysis process as an input liquid for the electrolysis process, and the solid matter can be discharged as iron oxide.
[0014] The reaction time of the above pressure leaching process may be 5 to 7 hours.
[0015] The leaching of the copper and the precipitation of the iron can be carried out simultaneously by the pressure leaching process.
[0016] According to the present invention, by controlling the reaction temperature, pressure, and post-reaction sulfuric acid concentration conditions of the pressure leaching process, the copper leaching rate of a raw material containing copper is maintained high, and by increasing the precipitation rate of iron, an additional process for removing iron components in a copper recovery process can be reduced.
[0017] In addition, the iron concentration in the electrolyte solution used in the electrolysis process can be reduced, thereby improving the current efficiency of the electrolysis process for copper recovery.
[0018] Figure 1 is a process flow diagram for recovering copper according to one embodiment of the present invention.
[0019] In a typical copper recovery process, copper-containing raw materials are leached into sulfuric acid. Iron, along with copper, is also leached into the sulfuric acid. If the iron leached into the sulfuric acid solution is fed into the electrolytic process as an electrolyte along with copper, the current efficiency of electrolysis for copper precipitation decreases. Therefore, it is necessary to maintain the leaching rate of copper contained in the sulfuric acid solution while precipitating and removing the iron.
[0020] The present invention aims to increase the current efficiency in an electrolytic process by leaching more than 95% of copper and precipitating and removing more than 84% of iron from a raw material containing copper through a pressurized leaching process.
[0021] Figure 1 is a process flow diagram for recovering copper according to one embodiment of the present invention.
[0022] Referring to Fig. 1, a raw material containing copper is introduced into an autoclave, which is a pressurized device, together with an acid solution, and is pressurized and leached while injecting oxygen into the autoclave (pressurized leaching process (10)). The acid solution may be a copper electrolyte solution having a copper component concentration of 30 g / L to 40 g / L and a sulfuric acid concentration of 160 g / L to 170 g / L. When a raw material containing copper is pressurized and leached together with the copper electrolyte solution, the copper included in the raw material is leached, and the iron included in the raw material may be precipitated in the form of iron oxide. In addition, the reaction time of the pressure leaching process (10) may be 5 to 7 hours. The oxygen introduced into the autoclave is used as an oxidizing agent.
[0023] Specifically, when raw materials including copper, iron, etc. are subjected to pressure leaching together with a copper electrolyte solution, copper and iron are leached in the form of sulfate according to the following reaction formulas (1) and (2). The temperature of the autoclave in which the pressure leaching process (10) is performed may be 150°C or more and 200°C or less, and the internal pressure of the autoclave may be 900 kPa or more and 2,000 kPa or less. The reaction formulas by which copper and iron contained in the raw materials are leached are as follows: reaction formulas (1) and (2).
[0024] CuS + H2SO4+ 1 / 2O2→ CuSO4+ H2O + S... Reaction formula (1)
[0025] FeS + H2SO4+ 1 / 2O2→ FeSO4+ H2O + S... Reaction formula (2)
[0026] Here, since the pressure leaching process (10) is performed by injecting oxygen into the autoclave, iron can be oxidized into the form of Fe(III) by the oxygen introduced. The reaction in which Fe(II) ions are oxidized into Fe(III) proceeds as shown in the reaction formula (3) below.
[0027] 2Fe 2+ + 2H + +1 / 2O2→ 2Fe 3+ + H2O... Reaction formula (3)
[0028] The iron component leached as Fe(III) is precipitated in the form of Jarosite according to the reaction formula (4) below or in the form of Hematite according to the reaction formula (5).
[0029] MSO4+ 3Fe2(SO4)3+12H2O → 2MFe3(SO4)2(OH)6+ 6H2SO4(M= K, Na) ... Reaction equation (4)
[0030] Fe2(SO4)3+ 4H2O → Fe2O3+ 3H2SO4+ H2O... Reaction formula (5)
[0031] By the above reaction, most of the copper contained in the raw material is leached into the copper electrolyte solution and exists in the form of copper ions in the solution, and most of the iron is precipitated as iron oxide in the form of iron or hematite. The leaching of copper and the precipitation of iron according to the above reaction formulas (1) to (5) are simultaneously carried out by the pressure leaching process (10).
[0032] Afterwards, the pressurized leaching process effluent discharged from the pressurized leaching process (10) is treated in a coolant and a filter, and the discharged solution is transferred to the electrolysis process (20) as the electrolysis process input liquid (15), and the solids are discharged as iron oxide.
[0033] The electrolytic process input liquid (15) that is introduced into the electrolytic process (20) can be viewed as a pure copper electrolytic feed liquid with a significant portion of impurities removed, and the electrolytic process input liquid (15) can be electrolytically collected and copper can be electroplated at the cathode to recover it.
[0034] Hereinafter, a pressure leaching process according to an embodiment of the present invention was performed using a raw material containing 29.8% copper (Cu), 23.5% lead (Pb), and 4.49% iron (Fe). The pressure leaching process was performed using an autoclave facility, and the reaction temperature and the sulfuric acid concentration of the post-pressure leaching process liquid after the reaction were changed. As the acid solution, a copper electrolyte solution containing 30 to 40 g / L of copper and 160 to 170 g / L of sulfuric acid was used. The solid density of the introduced raw material was set to 150 g / L, and the reaction was performed for 5 hours. The composition of the raw material containing copper used in the experiment is as follows.
[0035] Composition of copper raw material used in the experiment: Copper (Cu), Lead (Pb), Iron (Fe) content (%) 29.8 23.5 4.49
[0036] Example 1
[0037] In Example 1, the pressure leaching process according to the present invention was carried out under the conditions of 150°C and 900kPa by controlling the reaction temperature and pressure of the autoclave, and the leaching rate of copper components and the precipitation rate of iron components were measured by controlling the sulfuric acid concentration conditions in the post-pressure leaching process liquid after the reaction. In Example 1, the sulfuric acid concentration in the post-pressure leaching process liquid after the reaction was controlled to 20g / L, 40g / L, and 60g / L, and the iron precipitation rate (%) and copper leaching rate (%) were measured accordingly.
[0038] Iron precipitation rate and copper leaching rate according to sulfuric acid concentration at a reaction temperature of 150℃ Reaction temperature (℃) Sulfuric acid concentration in the post-pressure leaching process solution after reaction (g / L) Iron precipitation rate (%) Copper leaching rate (%) Invention example 11502098.183.3 Invention example 21504095.894.8 Comparative example 1150604.0195.1
[0039] Referring to Table 2, when the sulfuric acid concentration in the post-pressure leaching process liquid after the reaction was 20 g / L and 40 g / L at a reaction temperature of 150°C, the iron precipitation rate was 95% or higher, and the copper leaching rate was 83% or higher, showing high values for both the iron precipitation rate and the copper leaching rate. However, when the sulfuric acid concentration in the post-pressure leaching process liquid after the reaction was 60 g / L, the copper leaching rate was high at 95% or higher, but the iron precipitation rate was 4.01%, indicating that almost no iron was removed in the form of iron oxide, and it was found that a large amount of iron was contained in the post-pressure leaching process liquid. Therefore, when the sulfuric acid concentration in the post-pressure leaching process liquid after the reaction was 20 g / L to 40 g / L at a reaction temperature of 150°C, the concentration of iron in the electrolyte fed to the electrolytic process can be lowered, while most of the copper can be leached, thereby improving the current efficiency of the electrolytic process for copper recovery. On the other hand, when the concentration of sulfuric acid in the post-pressure leaching process liquid after the reaction is 60 g / L or more at a reaction temperature of 150°C, the precipitation rate of iron is very low, so a large amount of iron is included in the post-pressure leaching process liquid, and thus the current efficiency of the electrolytic process is lowered.
[0040] Example 2
[0041] In Example 2, the pressure leaching process according to the present invention was performed under the conditions of 160°C and 1,000 kPa by controlling the reaction temperature and pressure of the autoclave, and the leaching rate of copper components and the precipitation rate of iron components were measured by controlling the sulfuric acid concentration conditions in the post-pressure leaching process liquid after the reaction. In Example 2, the sulfuric acid concentration in the post-pressure leaching process liquid after the reaction was controlled to 20 g / L, 40 g / L, and 60 g / L, and the iron precipitation rate (%) and copper leaching rate (%) were measured accordingly.
[0042] Iron precipitation rate and copper leaching rate according to sulfuric acid concentration at a reaction temperature of 160℃ Reaction temperature (℃) Sulfuric acid concentration in the post-pressure leaching process solution after reaction (g / L) Iron precipitation rate (%) Copper leaching rate (%) Invention example 31602098.386.6 Invention example 41604096.494.6 Comparative example 2160606.4595.2
[0043] Referring to Table 3, when the sulfuric acid concentration in the post-pressure leaching process liquid after the reaction was 20 g / L and 40 g / L at a reaction temperature of 160°C, the iron precipitation rate was 96% or higher, and the copper leaching rate was 86% or higher, both of which were high values. However, when the sulfuric acid concentration in the post-pressure leaching process liquid after the reaction was 60 g / L, the copper leaching rate was high at 95% or higher, but the iron precipitation rate was 6.45%, indicating that almost no iron was removed in the form of iron oxide, and it was found that a large amount of iron was contained in the post-pressure leaching process liquid. Therefore, when the sulfuric acid concentration in the post-pressure leaching process liquid after the reaction was 20 g / L to 40 g / L at a reaction temperature of 160°C, the concentration of iron in the electrolyte fed to the electrolytic process can be lowered, while most of the copper can be leached, thereby improving the current efficiency of the electrolytic process for copper recovery. On the other hand, when the concentration of sulfuric acid in the post-pressure leaching process liquid after the reaction is 60 g / L or more at a reaction temperature of 160°C, the precipitation rate of iron is very low, so a large amount of iron is included in the post-pressure leaching process liquid, and thus the current efficiency of the electrolytic process is lowered.
[0044] Example 3
[0045] In Example 3, the pressure leaching process according to the present invention was performed under the conditions of 180°C and 1,400 kPa by controlling the reaction temperature and pressure of the autoclave, and the sulfuric acid concentration conditions in the post-pressure leaching process liquid after the reaction were controlled to measure the leaching rate of copper components and the precipitation rate of iron components. In Example 3, the sulfuric acid concentration in the post-pressure leaching process liquid after the reaction was controlled to 20 g / L, 60 g / L, and 80 g / L, and the iron precipitation rate (%) and copper leaching rate (%) were measured accordingly.
[0046] Iron precipitation rate and copper leaching rate according to sulfuric acid concentration at a reaction temperature of 180℃ Reaction temperature (℃) Sulfuric acid concentration in the post-pressure leaching process solution after reaction (g / L) Iron precipitation rate (%) Copper leaching rate (%) Invention example 51802098.591.3 Invention example 61806084.495.6 Comparative example 31808042.896.4
[0047] Referring to Table 4, when the concentration of sulfuric acid in the post-pressure leaching process liquid after the reaction at a reaction temperature of 180℃ was 20g / L and 60g / L, the iron precipitation rate was over 84%, and the copper leaching rate was over 91%, showing high values for both the iron precipitation rate and the copper leaching rate. It was confirmed that even when the concentration of sulfuric acid in the post-pressure leaching process liquid was as high as 60g / L at a reaction temperature of 180℃, a satisfactory iron precipitation rate of over 84% was shown. However, when the sulfuric acid concentration in the post-pressure leaching process liquid after the reaction was 80 g / L, the copper leaching rate was high at over 96%, but the iron precipitation rate was 42.8%, meaning that less than half of the iron in the solution was precipitated out, and it was found that a large amount of iron was contained in the post-pressure leaching process liquid. Therefore, when the sulfuric acid concentration in the post-pressure leaching process liquid after the reaction is 20 g / L to 60 g / L at a reaction temperature of 180°C, the concentration of iron in the electrolyte fed to the electrolysis process can be lowered while most of the copper can be leached, thereby improving the current efficiency of the electrolysis process for copper recovery. On the other hand, when the sulfuric acid concentration in the post-pressure leaching process liquid after the reaction is 80 g / L or more at a reaction temperature of 180°C, the iron precipitation rate is low, so that a large amount of iron is contained in the post-pressure leaching process liquid, and thus the current efficiency of the electrolysis process is lowered.
[0048] Example 4
[0049] In Example 4, the pressure leaching process according to the present invention was carried out under the conditions of 200°C and 2,000 kPa by controlling the reaction temperature and pressure of the autoclave, and the leaching rate of copper components and the precipitation rate of iron components were measured by controlling the sulfuric acid concentration conditions in the post-pressure leaching process liquid after the reaction. In Example 4, the sulfuric acid concentration in the post-pressure leaching process liquid after the reaction was controlled to 20 g / L, 60 g / L, and 80 g / L, and the iron precipitation rate (%) and copper leaching rate (%) were measured accordingly.
[0050] Iron precipitation rate and copper leaching rate according to sulfuric acid concentration at a reaction temperature of 200℃ Reaction temperature (℃) Sulfuric acid concentration in the post-pressure leaching process solution after reaction (g / L) Iron precipitation rate (%) Copper leaching rate (%) Invention example 72002098.892.8 Invention example 82006086.395.9 Comparative example 42008031.398.1
[0051] Referring to Table 5, when the concentration of sulfuric acid in the post-pressure leaching process liquid after the reaction at a reaction temperature of 200℃ was 20g / L and 60g / L, the iron precipitation rate was over 86%, and the copper leaching rate was over 92%, showing high values for both the iron precipitation rate and the copper leaching rate. It was confirmed that even when the concentration of sulfuric acid in the post-pressure leaching process liquid was as high as 60g / L at a reaction temperature of 200℃, a satisfactory iron precipitation rate of over 86% was shown. However, when the sulfuric acid concentration in the post-pressure leaching process liquid after the reaction was 80 g / L, the copper leaching rate was high at over 98%, but the iron precipitation rate was 31.3%, meaning that less than half of the iron in the solution was precipitated out, and it was found that a large amount of iron was contained in the post-pressure leaching process liquid. Therefore, when the sulfuric acid concentration in the post-pressure leaching process liquid after the reaction is 20 g / L to 60 g / L at a reaction temperature of 200°C, the concentration of iron in the electrolyte fed to the electrolysis process can be lowered while most of the copper can be leached, thereby improving the current efficiency of the electrolysis process for copper recovery. On the other hand, when the sulfuric acid concentration in the post-pressure leaching process liquid after the reaction is 80 g / L or more at a reaction temperature of 200°C, the iron precipitation rate is low, so that a large amount of iron is contained in the post-pressure leaching process liquid, and thus the current efficiency of the electrolysis process is lowered.
[0052] According to the above experimental results according to one embodiment of the present invention, when the reaction temperature inside the autoclave performing the pressure leaching process is maintained at 150°C to 200°C, the precipitation rate of iron contained in the copper sulfate solution can be 84% or more, and the leaching rate of copper can be 83% or more when the concentration of sulfuric acid in the after-liquid of the pressure leaching process is in the range of 20 g / L to 40 g / L.
[0053] In addition, when the reaction temperature inside the autoclave performing the pressure leaching process is maintained at 180°C to 200°C, the precipitation rate of iron contained in the copper sulfate solution can be 84% or more, and the leaching rate of copper can be 91% or more, when the concentration of sulfuric acid in the post-pressure leaching process liquid is in the range of 20 g / L to 60 g / L.
[0054] In particular, when the reaction temperature inside the autoclave performing the pressure leaching process is maintained at 150°C to 160°C and the concentration of sulfuric acid in the post-pressure leaching process liquid is maintained at 40 g / L, the precipitation rate of iron can be increased to 95% or more and the leaching rate of copper can be increased to 94% or more. In addition, even when the concentration of sulfuric acid in the post-pressure leaching process liquid is increased to 60 g / L, the precipitation rate of iron can be maintained at 84% or more and the leaching rate of copper can be maintained at 95% or more when the reaction temperature inside the autoclave is maintained at 180°C to 200°C.
[0055] As discussed above, according to the present invention, by controlling the reaction temperature and pressure of the pressure leaching process, as well as the concentration of sulfuric acid in the post-pressure leaching process solution, the copper leaching rate can be maintained at a high level, while also maintaining a high iron precipitation rate. This allows for a lower iron concentration in the electrolyte solution fed into the electrolytic process, thereby improving the current efficiency of the electrolytic process for copper recovery.
[0056] While the present invention has been described in connection with certain embodiments herein, it should be understood that various modifications and variations can be made without departing from the spirit and scope of the invention, as understood by those skilled in the art. Furthermore, such modifications and variations are intended to fall within the scope of the claims appended to this specification.
Claims
1. A pressure leaching process in which a raw material containing copper is pressurized and leached in a copper electrolyte solution containing copper and sulfuric acid, so that the copper contained in the raw material is leached and the iron contained in the raw material is precipitated in the form of iron oxide; and It includes an electrolytic process for recovering copper by electrolyzing the pressurized leaching process slurry discharged from the pressurized leaching process and depositing it on the cathode. The concentration of sulfuric acid in the liquid after the above pressurized leaching process is 20 g / L to 40 g / L, A method for recovering copper, wherein the reaction temperature of the above pressure leaching process is 150°C to 200°C.
2. In paragraph 1 In the above pressure leaching process, the precipitation rate of iron is 84% or more, A method for recovering copper, wherein the copper leaching rate in the above-mentioned pressure leaching process is 83% or more.
3. A pressure leaching process in which a raw material containing copper is pressurized and leached in a copper electrolyte solution containing copper and sulfuric acid, so that the copper contained in the raw material is leached and the iron contained in the raw material is precipitated in the form of iron oxide; and It includes an electrolytic process for recovering copper by electrolyzing the pressurized leaching process slurry discharged from the pressurized leaching process and depositing it on the cathode. The concentration of sulfuric acid in the liquid after the above pressurized leaching process is 20 g / L to 60 g / L, A method for recovering copper, wherein the reaction temperature of the above pressure leaching process is 180°C to 200°C.
4. In the third paragraph In the above pressure leaching process, the precipitation rate of iron is 84% or more, A method for recovering copper, wherein the copper leaching rate in the above-mentioned pressure leaching process is 91% or more.
5. In paragraph 1 or paragraph 3, The above pressure leaching process is a method for recovering copper using an autoclave.
6. In Article 5 A method for recovering copper, wherein the internal pressure of the autoclave is 900 kPa or more and 2,000 kPa or less.
7. In Article 5 A method for recovering copper, wherein the above-mentioned pressurized leaching process is performed by injecting oxygen into the autoclave.
8. In paragraph 1 or paragraph 3, A method for recovering copper, wherein the liquid after the above-mentioned pressurized leaching process is treated in a coolant and a filter, the discharged solution is transferred to an electrolytic process as an electrolytic process input liquid, and the solid matter is discharged as iron oxide.
9. In paragraph 1 or paragraph 3, A method for recovering copper, wherein the reaction time of the above pressure leaching process is 5 to 7 hours.
10. In paragraph 1 or paragraph 3, A method for recovering copper, wherein the leaching of the copper and the precipitation of the iron are carried out simultaneously by the pressure leaching process.