How to recover copper

Abstract

A method for recovering copper according to one embodiment of the present invention includes a pressure leaching process in which a copper-containing raw material is pressure-leached in a copper electrolytic solution containing copper and sulfuric acid, thereby leaching the copper contained in the raw material and precipitating the iron contained in the raw material in the form of iron oxide, and an electrolysis process in which the pressure leaching solution discharged from the pressure leaching process is electrolyzed to recover copper by electrodeposition at a negative electrode, wherein the sulfuric acid concentration in the pressure leaching solution is 20 g / L to 40 g / L, and the reaction temperature in the pressure leaching process is 150°C to 200°C.

Description

[Technical Field]

[0001] The present invention relates to a method for reducing the iron concentration in an electrolyte for copper recovery by pressure leaching a copper-containing raw material into a copper electrolytic effluent containing copper and sulfuric acid, thereby leaching the copper from the raw material and precipitating and removing the iron. [Background technology]

[0002] The process of recovering pure copper from copper-containing raw materials generally involves leaching the raw material in a sulfuric acid solution under atmospheric pressure or under pressure. In atmospheric leaching, the reaction time must be maintained for 16 hours or more to increase the copper leaching efficiency, and the increased consumption of oxygen and steam during this process increases the cost of copper recovery and reduces recovery efficiency.

[0003] Furthermore, raw materials containing copper also contain other elements such as iron, and in atmospheric leaching, iron components other than copper are also leached, causing an increase in the iron concentration in the electrolyte in the electrolysis process, which is the subsequent step in the leaching process. If the iron concentration in the electrolyte is high, the zinc electrodeposited on the negative electrode in the electrolysis process corrodes, reducing the hydrogen overvoltage, and the Fe contained in the sulfuric acid solution at the negative and positive electrodes 2+ , Fe 3+ The redox reaction of ions reduces the current efficiency and requires additional steps to remove impurities. Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides a method for recovering copper by adjusting the reaction temperature and pressure in the pressure leaching process and the sulfuric acid concentration after the reaction, thereby increasing the precipitation rate of iron while maintaining a high leaching rate of copper contained in the solution.

[0005] The present invention also provides a method for recovering copper, which can improve the current efficiency of the electrolysis step by reducing the iron concentration in the electrolyte solution fed to the electrolysis step. [Means for solving the problem]

[0006] A method for recovering copper according to one embodiment of the present invention includes a pressure leaching process in which a copper-containing raw material is pressure-leached in a copper electrolytic solution containing copper and sulfuric acid, thereby leaching the copper contained in the raw material and precipitating the iron contained in the raw material in the form of iron oxide, and an electrolysis process in which the pressure leaching solution discharged from the pressure leaching process is electrolyzed to recover copper by electrodeposition at a negative electrode, wherein the sulfuric acid concentration in the pressure leaching solution is 20 g / L to 40 g / L, and the reaction temperature in the pressure leaching process is 150°C to 200°C.

[0007] The pressure leaching step may have an iron precipitation rate of 84% or more, and the pressure leaching step may have a copper leaching rate of 83% or more.

[0008] A method for recovering copper according to another embodiment of the present invention includes a pressure leaching step in which a copper-containing raw material is pressure-leached in a copper electrolytic solution containing copper and sulfuric acid, thereby leaching the copper contained in the raw material and precipitating the iron contained in the raw material in the form of iron oxide, and an electrolysis step in which the pressure leaching solution discharged from the pressure leaching step is electrolyzed to recover copper by electrodeposition at a negative electrode, wherein the sulfuric acid concentration in the pressure leaching solution is 20 g / L to 60 g / L, and the reaction temperature in the pressure leaching step is 180°C to 200°C.

[0009] The pressure leaching step may have an iron precipitation rate of 84% or more, and the pressure leaching step may have a copper leaching rate of 91% or more.

[0010] The pressure leaching step can be carried out using an autoclave.

[0011] The internal pressure of the autoclave may be 900 kPa or more and 2,000 kPa or less.

[0012] The pressure leaching step may be carried out by injecting oxygen into the autoclave.

[0013] The liquid after the pressure leaching step is treated with a thickener and a filter, and the discharged solution is transferred to the electrolysis step as an input liquid for the electrolysis step, and the solid matter can be discharged as iron oxide.

[0014] The reaction time for the pressure leaching step may be 5 to 7 hours.

[0015] The copper leaching and the iron precipitation may be done simultaneously by the pressure leaching process. [Effects of the Invention]

[0016] According to the present invention, by adjusting the reaction temperature, pressure, and sulfuric acid concentration after the reaction in the pressure leaching process, the copper leaching rate of the copper-containing raw material can be maintained high and the iron precipitation rate can be increased, thereby reducing the need for an additional step for removing iron components in the copper recovery process.

[0017] Furthermore, the iron concentration in the electrolyte fed to the electrolysis step can be reduced, and the current efficiency of the electrolysis step for recovering copper can be improved. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a process flow diagram for recovering copper according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] In a typical copper recovery process, when raw materials containing copper are leached into sulfuric acid, iron and other substances are also leached into the sulfuric acid. If the iron leached into the sulfuric acid solution is added to the electrolysis process together with copper as an electrolyte, the current efficiency during electrolysis for copper precipitation decreases. Therefore, it is necessary to precipitate and remove the iron while maintaining the leaching rate of copper contained in the sulfuric acid solution.

[0020] In order to increase the current efficiency in the electrolysis process, the present invention aims to leach 95% or more of copper from a copper-containing raw material by pressure leaching and precipitate and remove 84% or more of iron.

[0021] FIG. 1 is a process flow diagram for recovering copper according to one embodiment of the present invention.

[0022] Referring to FIG. 1, a copper-containing raw material is introduced into an autoclave, which is a pressurizing device, together with an acid solution, and pressure leaching is performed while oxygen is injected into the autoclave (pressure leaching step (10)). The acid solution may be copper electrolytic tailings having a copper concentration of 30 g / L to 40 g / L and a sulfuric acid concentration of 160 g / L to 170 g / L. When the copper-containing raw material is pressure leached together with the copper electrolytic tailings, copper contained in the raw material is leached, and iron contained in the raw material may be precipitated in the form of iron oxide. The reaction time for the pressure leaching step (10) may be 5 to 7 hours. The oxygen introduced into the autoclave is used as an oxidizing agent.

[0023] Specifically, when raw materials containing copper, iron, etc. are pressure-leached together with copper electrolytic solution, copper and iron are leached in the form of sulfates according to the following reaction formulas (1) and (2). The temperature of the autoclave in which the pressure leaching step (10) is carried out may be 150°C or higher and 200°C or lower, and the internal pressure of the autoclave may be 900 kPa or higher and 2,000 kPa or lower. The reaction formulas by which copper and iron contained in the raw materials are leached are as shown in the following reaction formulas (1) and (2).

[0024] CuS+H2SO4+1 / 2O2→CuSO4+H2O+S...Reaction Equation (1)

[0025] FeS+H2SO4+1 / 2O2→FeSO4+H2O+S...Reaction equation (2)

[0026] Here, the pressure leaching step (10) is carried out while oxygen is being injected into the autoclave, so that iron can be oxidized to the form of Fe(III) by the oxygen introduced. The reaction of Fe(II) ions being oxidized to Fe(III) proceeds as shown in the following reaction formula (3).

[0027] 2Fe 2+ +2H ++1 / 2O2 → 2Fe 3+ +H2O...Reaction equation (3)

[0028] The iron component leached as Fe(III) is precipitated in the form of jarosite according to the following reaction (4) or hematite according to the following reaction (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 equation (5)

[0031] Through the above reactions, most of the copper contained in the raw material is leached into the copper electrolysis effluent and exists in the form of copper ions in the solution, while most of the iron is precipitated as iron oxide in the form of iron alumite or hematite. The leaching of copper and the precipitation of iron according to the above reaction formulas (1) to (5) are carried out simultaneously in the pressure leaching step (10).

[0032] Thereafter, the post-pressure leaching solution discharged from the pressure leaching step (10) is treated in a thickener and a filter, and the discharged solution is transferred to the electrolysis step (20) as the electrolysis step input solution 15, and the solid matter is discharged as iron oxide.

[0033] The electrolysis process input solution 15 input to the electrolysis process (20) can be said to be a pure copper electrolysis feed solution from which impurities have been substantially removed, and copper can be recovered by electrowinning the electrolysis process input solution 15 and electrodepositing it at the negative electrode.

[0034] Below, a pressure leaching process according to one embodiment of the present invention was carried out using a raw material containing 29.8% copper (Cu), 23.5% lead (Pb), and 4.49% iron (Fe). The pressure leaching process was carried out using an autoclave, and the reaction temperature and the sulfuric acid concentration of the post-pressure leaching solution were varied. The acid solution used was a copper electrolytic solution containing copper components at concentrations of 30-40 g / L and sulfuric acid at concentrations of 160-170 g / L. The solid density of the input raw material was set to 150 g / L, and the reaction was carried out for 5 hours. The composition of the copper-containing raw material used in the experiment is as follows:

[0035] Composition of copper raw material used in the experiment [Table 1]

[0036] Example 1

[0037] In Example 1, the autoclave reaction temperature and pressure were adjusted to carry out the pressure leaching process according to the present invention under conditions of 150°C and 900 kPa, and the sulfuric acid concentration in the post-pressure leaching liquor after the reaction was adjusted to measure the leaching yield of copper components and the precipitation yield of iron components. In Example 1, the sulfuric acid concentration in the post-pressure leaching liquor after the reaction was adjusted to 20 g / L, 40 g / L, and 60 g / L, and the iron precipitation yield (%) and copper leaching yield (%) were measured.

[0038] Iron precipitation rate and copper leaching rate depending on sulfuric acid concentration at a reaction temperature of 150°C [Table 2]

[0039] Referring to Table 2, when the sulfuric acid concentration in the pressure leaching solution after the reaction was 20 g / L or 40 g / L at a reaction temperature of 150°C, the iron precipitation rate was over 95% and the copper leaching rate was over 83%, both of which were high values. However, when the sulfuric acid concentration in the pressure leaching solution after the reaction was 60 g / L, the copper leaching rate was high at over 95%, but the iron precipitation rate was 4.01%, indicating that almost no iron was removed in the form of iron oxide, and a large amount of iron was contained in the pressure leaching solution. Therefore, when the sulfuric acid concentration in the pressure leaching solution after the reaction was 20 g / L to 40 g / L at a reaction temperature of 150°C, the iron concentration in the electrolyte input to the electrolysis step was reduced while most of the copper was leached, thereby improving the current efficiency of the electrolysis step for copper recovery. In contrast, when the reaction temperature is 150°C and the sulfuric acid concentration in the pressure leaching solution after the reaction is 60 g / L or more, the iron precipitation rate is very low and a large amount of iron is contained in the pressure leaching solution, resulting in a decrease in the current efficiency of the electrolysis step.

[0040] Example 2

[0041] In Example 2, the autoclave reaction temperature and pressure were adjusted to 160°C and 1,000 kPa to carry out the pressure leaching process according to the present invention, and the sulfuric acid concentration in the post-pressure leaching liquor after the reaction was adjusted to measure the leaching yield of copper components and the precipitation yield of iron components. In Example 2, the sulfuric acid concentration in the post-pressure leaching liquor after the reaction was adjusted to 20 g / L, 40 g / L, and 60 g / L, and the iron precipitation yield (%) and copper leaching yield (%) were measured.

[0042] Iron precipitation rate and copper leaching rate depending on sulfuric acid concentration at a reaction temperature of 160°C [Table 3]

[0043] Referring to Table 3, when the sulfuric acid concentration in the pressure leaching solution after the reaction was 20 g / L or 40 g / L at a reaction temperature of 160°C, the iron precipitation rate was over 96% and the copper leaching rate was over 86%, both of which were high values. However, when the sulfuric acid concentration in the pressure leaching solution after the reaction was 60 g / L, the copper leaching rate was high at over 95%, but the iron precipitation rate was 6.45%, indicating that almost no iron was removed in the form of iron oxide, and a large amount of iron was contained in the pressure leaching solution. Therefore, when the sulfuric acid concentration in the pressure leaching solution after the reaction was 20 g / L to 40 g / L at a reaction temperature of 160°C, the majority of copper could be leached while the iron concentration in the electrolyte input to the electrolysis step was reduced, thereby improving the current efficiency of the electrolysis step for copper recovery. In contrast, when the reaction temperature is 160°C and the sulfuric acid concentration in the pressure leaching solution after the reaction is 60 g / L or more, the iron precipitation rate is very low and a large amount of iron is contained in the pressure leaching solution, resulting in a decrease in the current efficiency of the electrolysis step.

[0044] Example 3

[0045] In Example 3, the autoclave reaction temperature and pressure were adjusted to 180°C and 1,400 kPa to carry out the pressure leaching process according to the present invention, and the sulfuric acid concentration in the post-pressure leaching liquor after the reaction was adjusted to measure the leaching yield of copper components and the precipitation yield of iron components. In Example 3, the sulfuric acid concentration in the post-pressure leaching liquor after the reaction was adjusted to 20 g / L, 60 g / L, and 80 g / L, and the iron precipitation yield (%) and copper leaching yield (%) were measured.

[0046] Iron precipitation rate and copper leaching rate depending on sulfuric acid concentration at a reaction temperature of 180°C [Table 4]

[0047] Referring to Table 4, when the reaction temperature was 180°C and the sulfuric acid concentration in the post-pressure leaching solution was 20 g / L or 60 g / L, the iron precipitation rate was over 84% and the copper leaching rate was over 91%, both of which were high values. It was also confirmed that at a reaction temperature of 180°C, even when the sulfuric acid concentration in the post-pressure leaching solution was as high as 60 g / L, an excellent iron precipitation rate of over 84% was achieved. However, when the sulfuric acid concentration in the post-pressure leaching solution was 80 g / L, the copper leaching rate was high at over 96%, but the iron precipitation rate was only 42.8%, indicating that less than half of the iron in the solution was precipitated and removed, indicating that the post-pressure leaching solution contained a large amount of iron. Therefore, when the reaction temperature is 180°C and the sulfuric acid concentration in the pressure leaching solution after the reaction is 20 g / L to 60 g / L, it is possible to leach most of the copper while reducing the iron concentration in the electrolyte added to the electrolysis step, thereby improving the current efficiency of the electrolysis step for copper recovery.In contrast, when the reaction temperature is 180°C and the sulfuric acid concentration in the pressure leaching solution after the reaction is 80 g / L or higher, the iron precipitation rate is low and a large amount of iron is contained in the pressure leaching solution, resulting in a decrease in the current efficiency of the electrolysis step.

[0048] Example 4

[0049] In Example 4, the autoclave reaction temperature and pressure were adjusted to 200°C and 2,000 kPa to carry out the pressure leaching process according to the present invention, and the sulfuric acid concentration in the post-pressure leaching liquor after the reaction was adjusted to measure the leaching yield of copper and the precipitation yield of iron. In Example 4, the sulfuric acid concentration in the post-pressure leaching liquor after the reaction was adjusted to 20 g / L, 60 g / L, and 80 g / L, and the iron precipitation rate (%) and copper leaching rate (%) were measured.

[0050] Iron precipitation rate and copper leaching rate depending on sulfuric acid concentration at a reaction temperature of 200°C [Table 5]

[0051] Referring to Table 5, when the reaction temperature was 200°C and the sulfuric acid concentration in the pressure leaching solution after the reaction was 20 g / L or 60 g / L, the iron precipitation rate was over 86% and the copper leaching rate was over 92%, showing high values ​​for both iron precipitation and copper leaching. It was also confirmed that at a reaction temperature of 200°C, even when the sulfuric acid concentration in the pressure leaching solution was as high as 60 g / L, an excellent iron precipitation rate of over 86% was achieved. However, when the sulfuric acid concentration in the pressure leaching solution after the reaction was 80 g / L, the copper leaching rate was high at over 98%, but the iron precipitation rate was only 31.3%, indicating that less than half of the iron in the solution was precipitated and removed, indicating that the pressure leaching solution contained a large amount of iron. Therefore, when the reaction temperature is 200°C and the sulfuric acid concentration in the pressure leaching solution after the reaction is 20 g / L to 60 g / L, it is possible to leach most of the copper while reducing the iron concentration in the electrolyte added to the electrolysis step, thereby improving the current efficiency of the electrolysis step for copper recovery.In contrast, when the reaction temperature is 200°C and the sulfuric acid concentration in the pressure leaching solution after the reaction is 80 g / L or higher, the iron precipitation rate is low and a large amount of iron is contained in the pressure leaching solution, resulting in a decrease in the current efficiency of the electrolysis step.

[0052] According to the above experimental results of one embodiment of the present invention, when the reaction temperature inside the autoclave where the pressure leaching process is performed is maintained at 150°C to 200°C, and the sulfuric acid concentration in the solution after the pressure leaching process is in the range of 20 g / L to 40 g / L, the iron precipitation rate in the copper sulfate solution can be 84% or more, and the copper leaching rate can be 83% or more.

[0053] Furthermore, when the reaction temperature inside the autoclave in which the pressure leaching process is carried out is maintained at 180°C to 200°C, and the sulfuric acid concentration in the solution after the pressure leaching process is in the range of 20 g / L to 60 g / L, 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.

[0054] In particular, when the reaction temperature inside the autoclave where the pressure leaching process is performed is maintained at 150°C to 160°C and the sulfuric acid concentration in the post-pressure leaching solution is maintained at 40 g / L, the iron precipitation rate can be increased to 95% or more and the copper leaching rate can be increased to 94% or more. Also, even if the sulfuric acid concentration in the post-pressure leaching solution is increased to 60 g / L, when the reaction temperature inside the autoclave is maintained at 180°C to 200°C, the iron precipitation rate can be maintained at 84% or more and the copper leaching rate can be maintained at 95% or more.

[0055] As discussed above, according to the present invention, by adjusting the reaction temperature and pressure in the pressure leaching step and the sulfuric acid concentration in the post-pressure leaching solution, it is possible to maintain a high copper leaching rate while also maintaining a high iron precipitation rate. This allows the iron concentration in the electrolyte input to the electrolysis step to be reduced, and the current efficiency of the electrolysis step for copper recovery to be improved.

[0056] While the present invention has been described herein with reference to certain embodiments, it will be apparent to those skilled in the art that various modifications and variations may be made without departing from the spirit and scope of the invention, and it is to be understood that such modifications and variations are within the scope of the appended claims.

Claims

1. a pressure leaching step in which a copper-containing raw material is pressure-leached in a copper electrolytic solution containing copper and sulfuric acid, thereby leaching the copper contained in the raw material and precipitating the iron contained in the raw material in the form of iron oxide; an electrolysis step of electrolyzing the pressure leaching solution discharged from the pressure leaching step and recovering copper by electrodeposition at a negative electrode, The concentration of sulfuric acid in the liquid after the pressure leaching step is 20 g / L to 40 g / L, The method for recovering copper, wherein the reaction temperature of the pressure leaching step is 150°C to 200°C.

2. The iron precipitation rate in the pressure leaching step is 84% ​​or more, 2. The method for recovering copper according to claim 1, wherein the leaching rate of copper in the pressure leaching step is 83% or more.

3. a pressure leaching step in which a copper-containing raw material is pressure-leached in a copper electrolytic solution containing copper and sulfuric acid, thereby leaching the copper contained in the raw material and precipitating the iron contained in the raw material in the form of iron oxide; an electrolysis step of electrolyzing the pressure leaching solution discharged from the pressure leaching step and recovering copper by electrodeposition at a negative electrode, The concentration of sulfuric acid in the liquid after the pressure leaching step is 20 g / L to 60 g / L, The method for recovering copper, wherein the reaction temperature of the pressure leaching step is 180°C to 200°C.

4. The iron precipitation rate in the pressure leaching step is 84% ​​or more, 4. The method for recovering copper according to claim 3, wherein the leaching rate of copper in the pressure leaching step is 91% or more.

5. 4. The method for recovering copper according to claim 1 or 3, wherein the pressure leaching step uses an autoclave.

6. 6. The method for recovering copper according to claim 5, wherein the internal pressure of the autoclave is 900 kPa or more and 2,000 kPa or less.

7. 6. The method of claim 5, wherein the pressure leaching step is carried out by injecting oxygen into the autoclave.

8. 4. The method for recovering copper according to claim 1 or 3, wherein the solution after the pressure leaching step is treated with a thickener and a filter, the discharged solution is transferred to an electrolysis step as an input solution for the electrolysis step, and the solid matter is discharged as iron oxide.

9. 4. The method for recovering copper according to claim 1 or 3, wherein the reaction time of the pressure leaching step is 5 to 7 hours.

10. 4. The method for recovering copper according to claim 1 or 3, wherein the copper leaching and the iron precipitation are carried out simultaneously by the pressure leaching process.

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