Method for purifying antimony and bismuth impurities in copper electrolyte

Abstract

The invention belongs to the field of copper electrolyte purification, and particularly relates to a method for purifying antimony and bismuth impurities in copper electrolyte, which comprises the following steps: mixing antimony and bismuth-containing copper electrolyte to be treated with a first impurity removal agent, carrying out first impurity removal treatment, and then carrying out solid-liquid separation to obtain first-stage treatment liquid and first-stage slag; a second impurity removal agent is added into the first-stage treatment liquid for second impurity removal treatment, and then solid-liquid separation is conducted to obtain purified copper electrolyte and second-stage residues; the first impurity removal agent is one or a mixture of phosphoric acid, copper phosphate, calcium phosphate and barium phosphate; the amount of the first impurity removing agent is 0.3-0.95 time of the sum of the amount of antimony and bismuth substances in the copper electrolyte to be treated; and the second impurity removal agent is a lanthanum-containing water-insoluble component. The first impurity removal agent and the second impurity removal agent are creatively adopted for carrying out two-stage impurity removal treatment, and combined control over components and conditions is matched, so that the physical and chemical characteristics of the copper electrolyte can be adapted, antimony and bismuth impurities in the copper electrolyte can be removed in a high-selectivity mode, and meanwhile introduction of a large number of impurities can be avoided.

Description

Technical Field

[0001] The invention relates to a method for purifying antimony and bismuth impurities in copper electrolyte, and belongs to the field of nonferrous metal metallurgy. Technical Background

[0002] Antimony and bismuth are the impurities that are most harmful to the copper electrolysis system. When the concentration of antimony and bismuth is too high, not only will the cathode copper impurity content exceed the standard and the cathode plate surface will be seriously granulated, but it will also cause problems such as electrolyte turbidity and reduced current efficiency. In order to ensure the efficient operation of the electrolysis system, copper smelters have strict control over antimony and bismuth impurities in copper electrolytes. However, with the closed-circuit production of copper smelters, insufficient open circuit of impurities, coupled with insufficient supply of high-quality copper concentrate, the antimony and bismuth impurities in the copper electrolysis system have been accumulating and increasing, resulting in the current copper electrolysis operation effect being generally affected. Therefore, the industry pays special attention to the open circuit problem of antimony and antimony in the copper smelting process, especially the efficient purification of antimony and bismuth in copper electrolytes.

[0003] For the purification of antimony and bismuth in copper electrolyte, technicians have carried out a lot of research work and made gratifying progress. They have developed copper electrolyte purification and impurity removal processes such as self-purification method, adsorption method, and ion exchange method. Among them, the self-purification method is the most mature and the most widely used. The self-purification method is to use arsenic, antimony, and bismuth in copper electrolyte to undergo coprecipitation reaction under certain conditions, and form insoluble arsenate precipitation, so that antimony and bismuth are removed. For example, the Chinese patent document with publication number CN110669932A discloses a method for comprehensive utilization of copper electrolyte purification resources, and specifically discloses a scheme for self-purification using a promoter containing Sb (III) / [Sb (III) + Bi (III) + Sb (IV) + Sb (V)]. The method is simple and low in cost, but the method has obvious limitations, requiring a certain proportion of arsenic, antimony, and bismuth in the electrolyte, otherwise the removal of impurities cannot be achieved, especially the removal effect of bismuth is not good.

[0004] To solve this problem, researchers have developed adsorption and ion exchange methods. For example, the patent document with publication number AU2018232890A1 discloses a resin for antimony removal and a regeneration method. The basic principles of these two methods for removing antimony and bismuth are very similar, except that the active materials used are different. The adsorption method usually uses antimony salts, zirconium salts or titanium salts, while the ion exchange method uses resins for impurity removal. Although the adsorption method or ion exchange method can remove antimony and bismuth, the effect is not good, the purification depth of antimony and bismuth is poor, and the copper loss is high. In addition, impurities are easily introduced during the application of these two methods, causing the electrolyte to be contaminated. Therefore, these two methods have not been widely used.

[0005] In summary, the existing electrolyte purification technology has many problems, such as high cost, easy introduction of impurities, high copper loss, and inability to remove antimony and bismuth simultaneously. It still needs to be further improved. The industry urgently needs to develop a method for purifying antimony and bismuth from copper electrolyte with simple process, low cost, and no pollution to the solution. Summary of the invention

[0006] In view of the problems that the removal selectivity of antimony and bismuth is not ideal due to high acid and high copper in the existing copper electrolyte, and new impurity components are easily introduced, the present invention provides a method for purifying antimony and bismuth impurities in copper electrolyte, aiming to provide a method that is adapted to the impurity removal characteristics of copper electrolyte and can remove antimony and bismuth impurities with high selectivity.

[0007] The main reason why it is difficult to purify and remove impurities from copper electrolyte is that the solution has high acidity and the concentration of impurity ions is relatively low. In addition, the purification process cannot introduce new impurities, which makes the materials or reagents that can be used very limited. Therefore, to achieve deep removal of antimony and bismuth, it is necessary to solve the problems of selectivity and impurity introduction. In view of the problems faced by copper electrolyte in removing antimony and bismuth impurities, the present invention has been studied in depth and provides the following improvement means:

[0008] A method for purifying antimony and bismuth impurities in a copper electrolyte, comprising mixing a copper electrolyte to be treated containing antimony and bismuth with a first impurity remover, performing a first impurity removal treatment, and then performing solid-liquid separation to obtain a first treatment liquid and a first slag; adding a second impurity remover to the first treatment liquid, performing a second impurity removal treatment, and then performing solid-liquid separation to obtain a purified copper electrolyte and a second slag;

[0009] The first impurity remover is one or a mixture of phosphoric acid, copper phosphate, calcium phosphate, and barium phosphate; and the first impurity remover is 0.3-0.95 times the sum of the amount of antimony and bismuth substances in the copper electrolyte to be treated;

[0010] The second impurity remover is a water-insoluble component containing lanthanum.

[0011] In view of the difficulty in removing antimony and bismuth impurities due to the characteristics of the copper electrolyte to be treated, the present invention innovatively adopts a first impurity remover and a second impurity remover to carry out the two-stage impurity removal treatment, and jointly controls the components and conditions. This can adapt to the physicochemical characteristics of the copper electrolyte, and can highly selectively remove the antimony and bismuth impurities therein, while avoiding the introduction of a large amount of cationic impurities.

[0012] In the present invention, the copper electrolyte to be treated is any copper electrolyte system with impurity removal requirements, such as a copper sulfate solution in which impurity ions of antimony and bismuth are dissolved. There are no special requirements for the characteristics of the components. For example, in order to obtain greater impurity removal process value, the concentrations of antimony and bismuth are above 0.2 g / L; the concentration of sulfuric acid is below 250 g / L. Furthermore, the concentration of Sb can be 0.3-1 g / L; the concentration of Bi can be 0.5-2 g / L. The concentration of sulfuric acid can be 100-200 g / L. There is no special requirement for the concentration of copper, for example, it can be 40-60 g / L.

[0013] In the present invention, the temperature of the first stage of impurity removal is 30-90°C, and can further be 40-85°C;

[0014] Preferably, the first stage of impurity removal takes 20-60 minutes, and can further be 30-55 minutes.

[0015] In the present invention, a reducing agent is also added in the first impurity removal treatment stage. The present invention has shown that adding a certain reducing agent can further cooperate with the first impurity removal agent to further improve the removal selectivity of antimony and bismuth impurities in the copper electrolyte.

[0016] In the present invention, the reducing agent includes at least one of sodium hypophosphite and hypophosphorous acid.

[0017] In the present invention, the amount of reducing agent added is 0.01-0.2 times the sum of the amounts of antimony and bismuth substances in the copper electrolyte to be treated; preferably 0.05-0.15 times.

[0018] In the present invention, the second impurity remover is at least one of lanthanum oxide, lanthanum carbonate and lanthanum hydroxide.

[0019] In the present invention, the amount of the second impurity remover added is 0.05-0.15 times the sum of the amounts of antimony and bismuth substances in the copper electrolyte to be treated.

[0020] In the present invention, the temperature of the second impurity removal treatment is 50-90°C;

[0021] Preferably, the second impurity removal treatment lasts for 30-90 minutes.

[0022] In the present invention, the solid-liquid separation is filtration or centrifugation.

[0023] Beneficial effects:

[0024] (1) The process of the present invention is simple, the reaction conditions are mild, no special equipment is required, and it is easy to realize industrial application.

[0025] (2) The impurity removal agent used in the present invention has a wide source and low cost, and the obtained antimony-bismuth slag can be used as a raw material for antimony-bismuth recovery, so the present invention has good economic and technical indicators.

[0026] (3) The purification effect of the present invention is good, and the concentration of antimony and bismuth in the purified liquid is much lower than the technical index of copper electrolyte.

[0027] (4) The present invention has low energy consumption, is environmentally friendly, and does not generate waste gas or waste water. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Attached Figure 1 The process flow chart of the present invention for purifying antimony and bismuth impurities from copper electrolyte

[0029] Attached Figure 2 This is the SEM-EDS analysis spectrum of the precipitate obtained by removing impurities in Example 4

[0030] Depend on Figure 2 It can be seen that the precipitated slag obtained after impurity removal contains, in addition to copper, other impurities such as antimony and bismuth, with contents of 0.13% and 57.67% respectively. This indicates that the phosphate precipitation method can effectively remove the antimony and bismuth impurities in the electrolyte, and the bismuth content in the purified slag is relatively high, which has good economic value.

[0031] The following examples are intended to further illustrate the present invention, rather than to limit the scope of the claims of the present invention.

[0032] Embodiment 1:

[0033] Step (1):

[0034] Measure 4.5m 3 Copper electrolyte (Cu: 51.43 g / L, Sb: 0.71 g / L, Bi: 1.83 g / L, H2SO4: 172 g / L) was placed in a reactor and heated to 65°C with stirring. Then, the first impurity remover copper phosphate was added in an amount of 0.34 times the total molar amount of antimony and bismuth in the electrolyte, and the reaction was kept warm for 35 minutes. After the reaction was completed, the primary filtrate and the primary filter residue were collected by filtration.

[0035] Step (2):

[0036] Add the primary filtrate to the reactor, stir and heat to 75°C. Then add the second impurity remover lanthanum oxide, the amount of which is 0.063 times the total molar amount of antimony and bismuth in the electrolyte, and keep warm for 55 minutes. After the reaction is completed, filter and collect the secondary filtrate and secondary filter residue. The secondary filtrate is the purified copper electrolyte. Sampling and analysis show that the concentrations of antimony and bismuth are 0.22 and 0.31 g / L respectively, the phosphorus concentration is less than 0.001 g / L, and the copper loss rate is less than 0.05%.

[0037] The above results show that the method has a good removal effect on antimony and bismuth in the electrolyte, and almost no other impurities such as phosphorus are introduced. The concentration of antimony and bismuth in the purified copper electrolyte can fully meet the technical requirements of the copper electrolyte.

[0038] Embodiment 2:

[0039] Compared with Example 1, the only difference is that the type of the first impurity remover is changed. The experimental groups are:

[0040] Group A: The first impurity remover is calcium phosphate, and the added amount is 0.43 times the total molar amount of antimony and bismuth in the electrolyte;

[0041] Group B: The first impurity remover is barium phosphate, and the added amount is 0.38 times the total molar amount of antimony and bismuth in the electrolyte;

[0042] Group C: The first impurity remover is phosphoric acid (85%), and the amount added is 0.43 times the total molar amount of antimony and bismuth in the electrolyte;

[0043] Group D: The first impurity remover is a mixture of calcium phosphate and phosphoric acid, the molar ratio of which is 2:1, and the amount added is 0.38 times the total molar amount of antimony and bismuth in the electrolyte;

[0044] Other operations and parameters are the same as in Example 1. The results are:

[0045] Group A: After the reaction, the concentrations of liquid antimony and bismuth were 0.26 g / L and 0.44 g / L respectively; the loss rate of Cu was only 0.09%; the phosphorus concentration was less than 0.001 g / L;

[0046] Group B: After the reaction, the concentrations of liquid antimony and bismuth were 0.24 g / L and 0.41 g / L respectively; the loss rate of Cu was 0.09%; the phosphorus concentration was less than 0.001 g / L;

[0047] Group C: After the reaction, the concentrations of liquid antimony and bismuth were 0.19 g / L and 0.29 g / L respectively; the loss rate of Cu was 0.02%; the phosphorus concentration was less than 0.001 g / L;

[0048] Group D: After the reaction, the concentrations of liquid antimony and bismuth were 0.23 g / L and 0.34 g / L respectively; the loss rate of Cu was 0.06%; and the phosphorus concentration was less than 0.001 g / L.

[0049] It can be seen from Example 2 that the use of a calcium phosphate-phosphoric acid combination as the first impurity remover can further enhance the impurity removal effect and selectivity.

[0050] Example 3: Case of adding reducing agent

[0051] Compared with Example 1, the only difference is that the reducing agent hypophosphorous acid is added in the first impurity removal stage, and the added amount is 0.09 times the total molar amount of antimony and bismuth in the electrolyte; other operations and parameters are the same as in Example 1.

[0052] The result is:

[0053] After the reaction, the concentrations of liquid antimony and bismuth were 0.11 g / L and 0.19 g / L respectively; the loss rate of Cu was 0.01%; and the phosphorus concentration was less than 0.001 g / L.

[0054] It can be seen from Examples 1 and 3 that, with the assistance of a reducing agent, the first impurity remover and the second impurity remover are further combined to further enhance the impurity removal effect and selectivity of Sb / Bi.

[0055] Embodiment 4:

[0056] Compared with Example 1, the only difference is that the type of the second impurity remover is changed. The experimental groups are:

[0057] Group A: The second impurity remover is lanthanum carbonate, and the added amount is 0.13 times the total molar amount of antimony and bismuth in the electrolyte;

[0058] Group B: The second impurity remover is lanthanum hydroxide, and the added amount is 0.11 times the total molar amount of antimony and bismuth in the electrolyte;

[0059] Other operations and parameters are the same as in Example 1. The results are:

[0060] Group A: After the reaction, the concentrations of liquid antimony and bismuth were 0.26 g / L and 0.38 g / L respectively; the loss rate of Cu was 0.03%; the phosphorus concentration was less than 0.001 g / L;

[0061] Group B: After the reaction, the concentrations of liquid antimony and bismuth were 0.28 g / L and 0.39 g / L respectively; the loss rate of Cu was 0.06%; and the phosphorus concentration was less than 0.001 g / L.

[0062] Comparative Example 1:

[0063] Compared with Example 1, the only difference is that the second stage impurity removal treatment of step 2 is not performed, that is, a first stage filtrate is directly sampled and analyzed, and the concentrations of antimony and bismuth are 0.35 and 0.47 g / L respectively, and the phosphorus concentration is as high as 236 mg / L.

[0064] By comparing Example 1 with Comparative Example 1, it can be seen that simply carrying out the first stage treatment does not provide ideal impurity removal effect and selectivity.

[0065] Comparative Example 2:

[0066] Compared with Example 1, the only difference is that an equal amount of lanthanum chloride is used to replace the lanthanum oxide; other operations and parameters are the same as in Example 1.

[0067] The concentrations of antimony and bismuth in the second-stage filtrate are 0.32 g / L and 0.45 g / L respectively; the loss rate of Cu is only 0.09%, and the phosphorus concentration is as high as 0.137 g / L.

[0068] Embodiment 5:

[0069] Measure 4.5m 3 Copper electrolyte (Cu: 51.43g / L, Sb: 0.71g / L, Bi: 1.83g / L, H2SO4: 172g / L) was stirred and heated to 40°C in a reactor. Phosphoric acid was then added as the first impurity remover in an amount of 0.63 times the total molar amount of antimony and bismuth in the electrolyte, and the reaction was kept warm for 50 minutes. After the reaction was completed, the primary filtrate and the primary filter residue were collected by filtration. The primary filtrate was added to the reactor and heated to 60°C with stirring. Lanthanum oxide was then added as the second impurity remover in an amount of 0.052 times the total molar amount of antimony and bismuth in the electrolyte, and the reaction was kept warm for 75 minutes. After the reaction was completed, the secondary filtrate and the secondary filter residue were collected by filtration. The secondary filtrate is the purified copper electrolyte. Sampling and analysis showed that the concentrations of antimony and bismuth were 0.25 and 0.33g / L, respectively, and the phosphorus concentration was less than 0.001g / L.

[0070] Embodiment 6:

[0071] Measure 4.5m 3 Copper electrolyte (Cu: 50.02g / L, Sb: 0.67g / L, Bi: 1.72g / L, H2SO4: 187g / L) was stirred and heated to 50°C in a reactor. Then copper phosphate was added as the first impurity remover in an amount of 0.46 times the total molar amount of antimony and bismuth in the electrolyte, and the reaction was kept warm for 40 minutes. After the reaction was completed, the primary filtrate and the primary filter residue were collected by filtration. The primary filtrate was added to the reactor and heated to 50°C with stirring. Then lanthanum oxide was added as the second impurity remover in an amount of 0.12 times the total molar amount of antimony and bismuth in the electrolyte, and the reaction was kept warm for 85 minutes. After the reaction was completed, the secondary filtrate and the secondary filter residue were collected by filtration. The secondary filtrate is the purified copper electrolyte. Sampling and analysis showed that the concentrations of antimony and bismuth were 0.17 and 0.28g / L, respectively, and the phosphorus concentration was less than 0.001g / L.

[0072] Embodiment 7:

[0073] Measure 4.5m 3Copper electrolyte (Cu: 48.76g / L, Sb: 0.56g / L, Bi: 1.44g / L, H2SO4: 176g / L) was stirred and heated to 75°C in a reactor. Calcium phosphate was then added as the first impurity remover in an amount of 0.43 times the total molar amount of antimony and bismuth in the electrolyte, and the reaction was kept warm for 35 minutes. After the reaction was completed, the primary filtrate and the primary filter residue were collected by filtration. The primary filtrate was added to the reactor and heated to 75°C with stirring. Lanthanum oxide was then added as the second impurity remover in an amount of 0.085 times the total molar amount of antimony and bismuth in the electrolyte, and the reaction was kept warm for 60 minutes. After the reaction was completed, the secondary filtrate and the secondary filter residue were collected by filtration. The secondary filtrate is the purified copper electrolyte. Sampling and analysis showed that the concentrations of antimony and bismuth were 0.16 and 0.25g / L, respectively, and the phosphorus concentration was less than 0.001g / L.

[0074] Embodiment 8:

[0075] Measure 4.5m 3 Copper electrolyte (Cu: 48.76g / L, Sb: 0.56g / L, Bi: 1.44g / L, H2SO4: 176g / L) was stirred and heated to 70°C in a reactor. Then barium phosphate was added as the first impurity remover in an amount of 0.49 times the total molar amount of antimony and bismuth in the electrolyte, and the reaction was kept warm for 30 minutes. After the reaction was completed, the primary filtrate and the primary filter residue were collected by filtration. The primary filtrate was added to the reactor and heated to 75°C with stirring. Then lanthanum oxide was added as the second impurity remover in an amount of 0.090 times the total molar amount of antimony and bismuth in the electrolyte, and the reaction was kept warm for 55 minutes. After the reaction was completed, the secondary filtrate and the secondary filter residue were collected by filtration. The secondary filtrate is the purified copper electrolyte. Sampling and analysis showed that the concentrations of antimony and bismuth were 0.15 and 0.27g / L, respectively, and the phosphorus concentration was less than 0.001g / L.

[0076] Embodiment 9:

[0077] Measure 4.5m 3 Copper electrolyte (Cu: 51.43g / L, Sb: 0.71g / L, Bi: 1.83g / L, H2SO4: 172g / L) was stirred and heated to 85°C in a reactor. Calcium phosphate was then added as the first impurity remover in an amount of 0.38 times the total molar amount of antimony and bismuth in the electrolyte, and the reaction was kept warm for 55 minutes. After the reaction was completed, the primary filtrate and the primary filter residue were collected by filtration. The primary filtrate was added to the reactor and heated to 80°C with stirring. Lanthanum oxide was then added as the second impurity remover in an amount of 0.077 times the total molar amount of antimony and bismuth in the electrolyte, and the reaction was kept warm for 35 minutes. After the reaction was completed, the secondary filtrate and the secondary filter residue were collected by filtration. The secondary filtrate is the purified copper electrolyte. Sampling and analysis showed that the concentrations of antimony and bismuth were 0.22 and 0.32g / L, respectively, and the phosphorus concentration was less than 0.001g / L.

[0078] Embodiment 10:

[0079] Measure 4.5m 3 Copper electrolyte (Cu: 50.02g / L, Sb: 0.67g / L, Bi: 1.72g / L, H2SO4: 187g / L) was stirred and heated to 60°C in a reactor. Then copper phosphate was added as the first impurity remover in an amount of 0.43 times the total molar amount of antimony and bismuth in the electrolyte, and the reaction was kept warm for 45 minutes. After the reaction was completed, the primary filtrate and the primary filter residue were collected by filtration. The primary filtrate was added to the reactor and heated to 85°C with stirring. Then lanthanum oxide was added as the second impurity remover in an amount of 0.11 times the total molar amount of antimony and bismuth in the electrolyte, and the reaction was kept warm for 40 minutes. After the reaction was completed, the secondary filtrate and the secondary filter residue were collected by filtration. The secondary filtrate is the purified copper electrolyte. Sampling and analysis showed that the concentrations of antimony and bismuth were 0.18 and 0.33g / L, respectively, and the phosphorus concentration was less than 0.001g / L.

Claims

1. A method for purifying antimony and bismuth impurities in copper electrolyte, characterized in that: The antimony- and bismuth-containing copper electrolyte to be treated is mixed with a first impurity remover, and a first impurity removal treatment is performed, followed by solid-liquid separation to obtain a first-stage treated liquid and a first-stage slag; a second impurity remover is added to the first-stage treated liquid, and a second impurity removal treatment is performed, followed by solid-liquid separation to obtain a purified copper electrolyte and a second-stage slag; The first impurity remover is one or a mixture of phosphoric acid, copper phosphate, calcium phosphate, and barium phosphate; and the first impurity remover is 0.3-0.95 times the sum of the amount of antimony and bismuth substances in the copper electrolyte to be treated; The second impurity remover is a water-insoluble component containing lanthanum.

2. The method for purifying antimony and bismuth impurities in copper electrolyte according to claim 1, characterized in that: The copper electrolyte to be treated is a copper sulfate solution in which impurity ions of antimony and bismuth are dissolved; Preferably, the concentration of antimony and bismuth is above 0.2 g / L; the concentration of sulfuric acid is below 250 g / L.

3. The method for purifying antimony and bismuth impurities in copper electrolyte according to claim 1, characterized in that: The temperature of the first stage of impurity removal is 30-90℃; Preferably, the first stage of impurity removal lasts for 20-60 minutes.

4. The method for purifying antimony and bismuth impurities in copper electrolyte according to any one of claims 1 to 3, characterized in that: A reducing agent is also added in the first impurity removal stage.

5. The method for purifying antimony and bismuth impurities in copper electrolyte according to claim 4, characterized in that: The reducing agent includes at least one of sodium hypophosphite and hypophosphorous acid.

6. The method for purifying antimony and bismuth impurities in copper electrolyte according to claim 5, characterized in that: The amount of reducing agent added is 0.01-0.2 times the sum of the amounts of antimony and bismuth substances in the copper electrolyte to be treated; preferably 0.05-0.15 times.

7. The method for purifying antimony and bismuth impurities in copper electrolyte according to claim 1, characterized in that: The second impurity remover is at least one of lanthanum oxide, lanthanum carbonate and lanthanum hydroxide.

8. The method for purifying antimony and bismuth impurities in copper electrolyte according to claim 1, characterized in that: The amount of the second impurity remover added is 0.05-0.15 times the sum of the amounts of antimony and bismuth substances in the copper electrolyte to be treated.

9. The method for purifying antimony and bismuth impurities in copper electrolyte according to claim 1, characterized in that: The temperature of the second impurity removal treatment is 50-90°C; Preferably, the second impurity removal treatment lasts for 30-90 minutes.

10. The method for purifying antimony and bismuth impurities in copper electrolyte according to claim 1, characterized in that: The solid-liquid separation is filtration or centrifugation.

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