A zinc-removed nickel sulfate solution, a method for removing zinc therefrom and applications thereof

Abstract

The present application relates to the technical field of zinc removal from nickel sulfate solution, and discloses a zinc-removed nickel sulfate solution, a method for removing zinc from the solution and application of the solution, which comprises the following steps: pretreatment of the feed liquid: adjusting the zinc-containing nickel sulfate solution to a nickel-zinc mass ratio of 70-102:1, and controlling the pH of the feed liquid to be 3-6 to obtain a pretreated nickel sulfate solution; pretreatment of the resin; adsorption and zinc removal; and regeneration of the resin, wherein the present application first systematically explores the key process parameters of the feed liquid pH and nickel-zinc mass ratio in the field of zinc removal from nickel sulfate solution by using TP204 resin, and determines the optimal adsorption range as pH 3-6 and nickel-zinc mass ratio 70-102:1, and preferably pH 4.3 and nickel-zinc ratio 74:1, under which the adsorption selectivity of the TP204 resin to zinc is optimal, the zinc content in the solution after zinc removal can be reduced to below 200 ppm, and the nickel loss rate is less than or equal to 5%, thereby solving the problems of poor adsorption accuracy and high nickel loss rate caused by the fuzzy parameters in the traditional process.

Description

Technical Field

[0001] This invention relates to the field of zinc removal technology using nickel sulfate solution, and more particularly to a zinc-removed nickel sulfate solution, its zinc removal method, and its application. Background Technology

[0002] Battery-grade nickel sulfate, a core raw material for lithium-ion battery cathodes, has stringent requirements regarding impurity content. Zinc, as one of the main impurities, must be controlled at extremely low levels; otherwise, it will severely affect the battery's electrochemical performance. Currently, in the industrial preparation of battery-grade nickel sulfate, the crude nickel sulfate solution often contains impurities such as zinc and cobalt at around 1 g / L. Zinc must be removed first, followed by cobalt removal purification. Resin adsorption, due to its combination of the selectivity of solvent extraction and the high efficiency of ion exchange, has become the mainstream method for removing zinc from nickel sulfate solutions.

[0003] TP204 resin is a macroporous polymer resin loaded with di(2-ethylhexyl)phosphoric acid (D2EHPA) groups. It exhibits specific adsorption selectivity for various metal ions in acidic environments, with the selectivity order being Fe... 3+ >Zn 2+ >Ca 2+ >Cu 2+ >Mn 2+ >Co 2+ >Mg 2+ >Ni 2+ Theoretically, TP204 resin can achieve efficient separation of zinc and nickel in nickel sulfate solution. However, in practical industrial applications, the use of TP204 resin to treat nickel sulfate solution generally suffers from poor adsorption precision, low zinc removal efficiency, and high nickel loss rate. The core reason is that the existing process does not clearly define the precise process parameters for zinc removal by TP204 resin, and the control of key factors such as pH of the feed solution and the nickel-zinc mass ratio lacks scientific basis: when the pH is too low, the resin has almost no adsorption effect on zinc; when the pH is too high, the resin's adsorption selectivity for cobalt and zinc decreases, while the co-adsorption loss of nickel increases; and an imbalance in the nickel-zinc ratio in the feed solution will further lead to the resin adsorption sites being occupied by nickel ions, reducing the zinc adsorption efficiency.

[0004] Existing technologies for TP204 resin applications primarily focus on the separation of cobalt and nickel. Research on deep zinc removal from nickel sulfate solutions is limited, and a precise, industrially applicable TP204 resin zinc removal method with precisely controlled process parameters has not yet been developed, failing to meet the high requirements of battery-grade nickel sulfate refining. Therefore, developing a TP204 resin-based process for deep zinc removal from nickel sulfate solutions through precise pH and nickel-zinc ratio control is crucial for solving the challenges of battery-grade nickel sulfate refining. Summary of the Invention

[0005] This invention provides a zinc-removed nickel sulfate solution, a zinc removal method thereon, and its application, overcoming the shortcomings of the prior art. It can effectively solve the problems of poor adsorption accuracy and high nickel loss caused by ambiguous parameters in existing methods for removing Zn ions from nickel sulfate solutions.

[0006] To solve the above problems, one of the technical solutions of this invention is achieved through the following method: a method for removing zinc from a nickel sulfate solution, comprising the following steps: Pretreatment of the solution: Adjust the zinc-containing nickel sulfate solution to a nickel-zinc mass ratio of 70~102:1 and control the pH of the solution to 3~6 to obtain a pretreated nickel sulfate solution; Resin pretreatment: TP204 resin was packed into an adsorption column and pretreated with a 3 BV, 3 mol / L sulfuric acid solution. The resin was then washed with deionized water until the pH of the eluent was 5-7, thus obtaining the pretreated TP204 resin adsorption column. Adsorption for zinc removal: The pretreated nickel sulfate solution is passed through the pretreated TP204 resin adsorption column at a flow rate of 1 BV / h. The effluent is collected in segments until the zinc content in the effluent reaches the preset index, thus completing the adsorption process and obtaining a zinc-removed nickel sulfate solution. Resin regeneration: After adsorption saturation, the TP204 resin is eluted with a 3BV, 3mol / L sulfuric acid solution to generate an eluent. The eluent is then regenerated to form a regenerated solution. The regenerated solution is collected and subjected to full analysis. If the regenerated solution contains nickel, the pH of the eluent is lowered; if the regenerated solution does not contain zinc, the pH of the adsorption solution is raised. The regenerated TP204 resin is returned to the resin pretreatment step for recycling.

[0007] In the above-mentioned pretreatment of the feed solution, the zinc-sulfur-nickel solution is the crude solution in the preparation process of battery-grade nickel sulfate. The crude solution has a nickel content of 18~114 g / L, a zinc content of 0.23~0.76 g / L, and a cobalt content of 0.226~1.4 g / L.

[0008] In the above raw material pretreatment, the zinc-containing nickel sulfate solution was adjusted to a nickel-zinc mass ratio of 74:1, and the pH of the solution was controlled at 4.3.

[0009] In the above-mentioned zinc adsorption process, the effluent is collected in segments, which are divided into segments of 1~3 BV, 4~6 BV, 7~9 BV, 10~12 BV, 13~15 BV, and 15~18 BV. The nickel content, zinc content, and pH value of the effluent in each segment are monitored in real time to monitor the adsorption efficiency of TP204 resin.

[0010] In the above resin regeneration process, the flow rate of the sulfuric acid solution used for regeneration is consistent with the feed flow rate of the adsorption process, both being 1 BV / h, to ensure sufficient resin desorption.

[0011] The above-mentioned adsorption columns are arranged in multiple series or parallel configurations.

[0012] The second technical solution of the present invention is achieved by the following method: a zinc-removed nickel sulfate solution, which is prepared by a zinc removal method for a nickel sulfate solution.

[0013] The third technical solution of the present invention is achieved in the following way: the application of a zinc-removed nickel sulfate solution, wherein the zinc-removed nickel sulfate solution is directly introduced into the subsequent cobalt removal process to prepare battery-grade nickel sulfate.

[0014] Compared with the prior art, the present invention has the following advantages: 1. This invention is the first to systematically investigate key process parameters such as pH and nickel-zinc mass ratio of TP204 resin in the field of zinc removal from nickel sulfate solution. The optimal adsorption range was determined to be pH 3-6 and nickel-zinc mass ratio 70-102:1, with pH 4.3 and nickel-zinc ratio 74:1 being preferred. Under these parameters, TP204 resin exhibits the best adsorption selectivity for zinc, and the zinc content in the solution after zinc removal can be reduced to below 200 ppm, with a nickel loss rate ≤5%. This solves the problems of poor adsorption accuracy and high nickel loss caused by ambiguous parameters in traditional processes.

[0015] 2. The process method of the present invention is adapted to the refining production process of battery-grade nickel sulfate. The nickel sulfate solution after zinc removal can directly enter the subsequent cobalt removal process without additional pH adjustment or impurity removal steps, which simplifies the production process, improves production efficiency, and the process is simple to operate and easy to automate, and has good prospects for industrial application. Detailed Implementation

[0016] The present invention is not limited to the following embodiments, and specific implementation methods can be determined according to the technical solutions and actual conditions of the present invention.

[0017] Example 1: This embodiment of the invention discloses a method for removing zinc from a nickel sulfate solution, comprising the following steps: S101, Pretreatment of solution: Adjust the zinc-containing nickel sulfate solution to a nickel-zinc mass ratio of 70~102:1, control the pH of the solution to 3~6, ​​and obtain the pretreated nickel sulfate solution. S102, Resin pretreatment: TP204 resin is packed into an adsorption column and pretreated with a 3 BV, 3 mol / L sulfuric acid solution. The resin is then washed with deionized water until the pH of the eluent is 5-7, thus obtaining the pretreated TP204 resin adsorption column. S103, Adsorption for zinc removal: The pretreated nickel sulfate solution is passed through the pretreated TP204 resin adsorption column at a flow rate of 1 BV / h. The effluent is collected in segments until the zinc content in the effluent reaches the preset index, thus completing the adsorption process and obtaining a zinc-removed nickel sulfate solution. S104, Resin Regeneration: After adsorption saturation, the TP204 resin is desorbed using a 3BV, 3mol / L sulfuric acid solution to generate an eluent. The eluent is then regenerated to form a regenerated solution. The regenerated solution is collected and subjected to full analysis. If the regenerated solution contains nickel, the pH of the eluent is lowered; if the regenerated solution does not contain zinc, the pH of the adsorption solution is raised. The regenerated TP204 resin is returned to the resin pretreatment step for recycling.

[0018] In step S101 above, the zinc-sulfur-nickel solution in the pretreatment of the feed solution is the crude solution in the preparation process of battery-grade nickel sulfate. The crude solution has a nickel content of 18~114 g / L, a zinc content of 0.23~0.76 g / L, and a cobalt content of 0.226~1.4 g / L.

[0019] In step S101 above, during the raw material pretreatment, preferably, the zinc-containing nickel sulfate solution is adjusted to a nickel-zinc mass ratio of 74:1, and the pH of the solution is controlled at 4.3. At this point, the TP204 resin exhibits optimal adsorption selectivity for zinc and the lowest nickel loss rate.

[0020] In step S103 above, the effluent is collected in segments during the adsorption and removal of zinc. The effluent is divided into segments of 1~3 BV, 4~6 BV, 7~9 BV, 10~12 BV, 13~15 BV, and 15~18 BV. The nickel content, zinc content, and pH value of the effluent in each segment are detected in real time to monitor the adsorption efficiency of the TP204 resin.

[0021] In step S104 above, during resin regeneration, the flow rate of the sulfuric acid solution used for regeneration is consistent with the flow rate of the feed liquid in the adsorption process, both being 1 BV / h, to ensure sufficient resin desorption. Desorption involves washing away the impurities adsorbed by the resin. Regeneration is similar to treating the resin with sulfuric acid during the pretreatment process to give it adsorption capacity.

[0022] The method of this invention is adapted to industrial continuous production. As needed, multiple adsorption columns can be set up in series or in parallel, and the processing capacity can be adjusted according to production needs.

[0023] Example 2: This embodiment of the invention discloses a zinc-removed nickel sulfate solution, which is prepared using a zinc removal method for nickel sulfate solution.

[0024] Example 3: An application of nickel sulfate solution after zinc removal, wherein the nickel sulfate solution after zinc removal is directly used in the subsequent cobalt removal process to prepare battery-grade nickel sulfate.

[0025] Example 4: The crude nickel sulfate solution processed in this example is the feed solution from the preparation process of battery-grade nickel sulfate. The original solution contains 18.567 g / L nickel, 0.252 g / L zinc, and 0.228 g / L cobalt, with a nickel-zinc mass ratio of 74:1. The specific zinc removal steps are as follows: (1) Pretreatment of feed solution: Add dilute sulfuric acid to the original solution to adjust the pH of the feed solution to 4.3, and keep the nickel-zinc mass ratio at 74:1. (2) Resin pretreatment: TP204 resin was packed into an adsorption column, and 3 BV, 3 mol / L sulfuric acid solution was added for pretreatment at a flow rate of 1 BV / h. Then it was washed with deionized water until pH=6. (3) Adsorption for zinc removal: The pretreated liquid was passed through the adsorption column at a flow rate of 1 BV / h. The effluent was collected in segments of 1~3 BV and 4~6 BV. The nickel content in the 3 BV effluent was 18.694 g / L and the zinc content was 0.138 g / L. The zinc removal rate was 45.2% and the nickel loss rate was <1%. (4) Resin regeneration: After adsorption saturation, the resin was desorbed with 3BV, 3mol / L sulfuric acid solution at a flow rate of 1BV / h. The regenerated liquid was collected and analyzed. No nickel ions were detected, and the zinc ion desorption rate reached 98%. The regenerated resin was washed with water until pH=6 and could be recycled.

[0026] Example 5: The crude nickel sulfate solution treated in this example has a nickel content of 39.653 g / L, a zinc content of 0.39 g / L, and a cobalt content of 1.27 g / L, with a nickel-zinc mass ratio of 102:1. The specific zinc removal steps are as follows: (1) Pretreatment of the feed solution: Add dilute alkali solution to the original solution to adjust the pH of the feed solution to 3.5 and maintain the nickel-zinc mass ratio of 102:1; (2) Resin pretreatment: TP204 resin was packed into an adsorption column, and 3 BV, 3 mol / L sulfuric acid solution was added for pretreatment at a flow rate of 1 BV / h. Then it was washed with deionized water until pH=5. (3) Adsorption for zinc removal: The feed solution was passed through the adsorption column at a flow rate of 1 BV / h. The nickel content in the effluent was 38.336 g / L and the zinc content was 0.258 g / L at a flow rate of 3 BV. The zinc removal rate was 33.8% and the nickel loss rate was ≤3%. (4) Resin regeneration: Same as in Example 4, but nickel ions were not detected in the regeneration solution, the zinc desorption rate reached 97%, and the resin can be recycled.

[0027] Example 6: The crude nickel sulfate solution processed in this example was a self-prepared solution with a nickel content of 25.907 g / L and a zinc content of 0.262 g / L, and a nickel-zinc mass ratio of 99:1. The specific zinc removal steps are as follows: (1) Pretreatment of the feed solution: Adjust the pH of the feed solution to 5 and maintain the nickel-zinc mass ratio of 99:1; (2) Resin pretreatment: TP204 resin was packed into an adsorption column, and 3 BV, 3 mol / L sulfuric acid solution was added for pretreatment at a flow rate of 1 BV / h. Then it was washed with deionized water until pH=7. (3) Adsorption for zinc removal: The feed solution was passed through the adsorption column at a flow rate of 1 BV / h. The nickel content in the effluent was 22.122 g / L and the zinc content was 0.167 g / L at a flow rate of 3 BV. The zinc removal rate reached 36.3% and the nickel loss rate was ≤4%. (4) Resin regeneration: Same as in Example 1, the zinc desorption rate in the regeneration solution reached 99%, and the adsorption efficiency of the resin did not decrease significantly after recycling.

[0028] Example 7: The crude nickel sulfate solution processed in this example was a self-prepared solution with a nickel content of 18 g / L, a zinc content of 0.23 g / L, and a cobalt content of 0.226 g / L, with a nickel-zinc mass ratio of 70:1. The specific zinc removal steps are as follows: (1) Pretreatment of the feed solution: Adjust the pH of the feed solution to 3 and maintain the nickel-zinc mass ratio of 70:1; (2) Resin pretreatment: TP204 resin was packed into an adsorption column, and 3 BV, 3 mol / L sulfuric acid solution was added for pretreatment at a flow rate of 1 BV / h. Then it was washed with deionized water until pH=6. (3) Adsorption for zinc removal: The feed solution was passed through the adsorption column at a flow rate of 1 BV / h. The effluent at 3 BV had a nickel content of 16.25 g / L and a zinc content of 0.10 g / L. The zinc removal rate reached 56.52%, and the nickel loss rate was ≤4%. (4) Resin regeneration: Same as in Example 4, the zinc desorption rate in the regeneration solution reached 99%, and the adsorption efficiency of the resin did not decrease significantly after recycling.

[0029] Example 8: The crude nickel sulfate solution processed in this example was a self-prepared solution with a nickel content of 114 g / L, a zinc content of 0.76 g / L, and a cobalt content of 1.4 g / L, with a nickel-zinc mass ratio of 100:1. The specific zinc removal steps are as follows: (1) Pretreatment of the feed solution: Adjust the pH of the feed solution to 3 and maintain the nickel-zinc mass ratio of 100:1; (2) Resin pretreatment: TP204 resin was packed into an adsorption column, and 3 BV, 3 mol / L sulfuric acid solution was added for pretreatment at a flow rate of 1 BV / h. Then it was washed with deionized water until pH=6. (3) Adsorption for zinc removal: The feed solution was passed through the adsorption column at a flow rate of 1 BV / h. The effluent at 3 BV had a nickel content of 108 g / L and a zinc content of 0.24 g / L. The zinc removal rate reached 68.42%, and the nickel loss rate was ≤4%. (4) Resin regeneration: Same as in Example 4, the zinc desorption rate in the regeneration solution reached 99%, and the adsorption efficiency of the resin did not decrease significantly after recycling.

[0030] In this invention, the unit of mass ratio is 1.

[0031] In summary, compared with the prior art, the present invention has the following advantages: 1. This invention is the first to systematically investigate key process parameters such as pH and nickel-zinc mass ratio of TP204 resin in the field of zinc removal from nickel sulfate solution. The optimal adsorption range was determined to be pH 3-6 and nickel-zinc mass ratio 70-102:1, with pH 4.3 and nickel-zinc ratio 74:1 being preferred. Under these parameters, TP204 resin exhibits the best adsorption selectivity for zinc, and the zinc content in the solution after zinc removal can be reduced to below 200 ppm, with a nickel loss rate ≤5%. This solves the problems of poor adsorption accuracy and high nickel loss caused by ambiguous parameters in traditional processes.

[0032] 2. The process method of the present invention is adapted to the refining production process of battery-grade nickel sulfate. The nickel sulfate solution after zinc removal can directly enter the subsequent cobalt removal process without additional pH adjustment or impurity removal steps, which simplifies the production process, improves production efficiency, and the process is simple to operate and easy to automate, and has good prospects for industrial application.

Claims

1. A method for removing zinc from a nickel sulfate solution, characterized in that, Includes the following steps: Pretreatment of the solution: Adjust the zinc-containing nickel sulfate solution to a nickel-zinc mass ratio of 70~102:1 and control the pH of the solution to 3~6 to obtain a pretreated nickel sulfate solution; Resin pretreatment: TP204 resin was packed into an adsorption column and pretreated with a 3 BV, 3 mol / L sulfuric acid solution. The resin was then washed with deionized water until the pH of the eluent was 5-7, thus obtaining the pretreated TP204 resin adsorption column. Adsorption for zinc removal: The pretreated nickel sulfate solution is passed through the pretreated TP204 resin adsorption column at a flow rate of 1 BV / h. The effluent is collected in segments until the zinc content in the effluent reaches the preset index, thus completing the adsorption process and obtaining a zinc-removed nickel sulfate solution. Resin regeneration: After adsorption saturation, the TP204 resin is eluted with a 3BV, 3mol / L sulfuric acid solution to generate an eluent. The eluent is then regenerated to form a regenerated solution. The regenerated solution is collected and subjected to full analysis. If the regenerated solution contains nickel, the pH of the eluent is lowered; if the regenerated solution does not contain zinc, the pH of the adsorption solution is raised. The regenerated TP204 resin is returned to the resin pretreatment step for recycling.

2. The method for removing zinc from nickel sulfate solution according to claim 1, characterized in that, In the feed solution pretreatment, the zinc-sulfur-nickel solution is the crude solution in the battery-grade nickel sulfate preparation process, with a nickel content of 18~114 g / L, a zinc content of 0.23~0.76 g / L, and a cobalt content of 0.226~1.4 g / L.

3. The method for removing zinc from nickel sulfate solution according to claim 1, characterized in that, In the raw material pretreatment, the zinc-containing nickel sulfate solution is adjusted to a nickel-zinc mass ratio of 74:1, and the pH of the solution is controlled at 4.

3.

4. The method for removing zinc from nickel sulfate solution according to claim 1, characterized in that, In the zinc adsorption process, the effluent is collected in segments, which are divided into segments of 1~3 BV, 4~6 BV, 7~9 BV, 10~12 BV, 13~15 BV, and 15~18 BV. The nickel content, zinc content, and pH value of the effluent in each segment are detected in real time to monitor the adsorption efficiency of TP204 resin.

5. The method for removing zinc from nickel sulfate solution according to claim 1, characterized in that, In the resin regeneration process, the flow rate of the sulfuric acid solution used for regeneration is consistent with the feed flow rate of the adsorption process, both being 1 BV / h, to ensure sufficient resin desorption.

6. The method for removing zinc from nickel sulfate solution according to claim 1, characterized in that, Multiple adsorption columns are arranged in series or parallel.

7. A nickel sulfate solution after zinc removal, characterized in that, The zinc-removed nickel sulfate solution was prepared using a zinc removal method for nickel sulfate solution as described in any one of claims 1 to 6.

8. An application of the nickel sulfate solution after zinc removal as described in claim 7, characterized in that, After zinc removal, the nickel sulfate solution is directly fed into the subsequent cobalt removal process to prepare battery-grade nickel sulfate.