Process for the purification of a nickel sulfate solution

Abstract

The present application belongs to the technical field of impurity removal of nickel sulfate solution, and particularly relates to a method for removing impurities from nickel sulfate solution. First, the P204 extractant is used to extract the nickel sulfate raw solution F1 once to remove the Ca, Cu, Mn and Zn impurities in F1, and obtain the impurity-removed nickel sulfate solution F2. Then, the P507 extractant is used to extract F2 to obtain the second organic phase containing impurities and the secondary impurity-removed nickel sulfate solution F3. Finally, the F3 solution is extracted for the third time to obtain the target product nickel sulfate solution and high-purity magnesium solution. The method disclosed in the present application can obtain the by-products high-purity cobalt and high-purity magnesium solution while preparing the nickel sulfate solution. Compared with the traditional preparation process of nickel sulfate, the method disclosed in the present application has a more reasonable process design, is simpler to operate and has a lower production cost.

Description

Technical Field

[0001] This invention belongs to the field of nickel sulfate solution impurity removal technology, specifically relating to a method for removing impurities from nickel sulfate solution. Background Technology

[0002] With the rapid development of the new energy industry, the demand for battery raw materials has surged, necessitating an increase in existing production, especially for nickel, cobalt, and manganese. This increased production also places higher demands on the production process. In existing technologies, the extraction process for preparing nickel sulfate and cobalt sulfate solutions is extremely complex, with the two processes largely separate. The nickel raw material must pass through a nickel P204 line to remove impurities such as calcium, copper, manganese, and zinc, then through a nickel P507 magnesium line and enrichment line, finally passing through a C272 purification line to obtain the nickel sulfate solution. Meanwhile, the byproduct of nickel P204, waste cobalt, due to its high cobalt content, can be fed together with the cobalt raw material as cobalt feedstock. This cobalt feedstock then passes through cobalt P204, cobalt P507 lines, and a cobalt purification line to obtain the cobalt solution. The entire process is complex and requires significant initial investment. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention provides a method for removing impurities from nickel sulfate solution, which specifically includes the following:

[0004] A method for removing impurities from a nickel sulfate solution includes the following steps:

[0005] (1) First extraction: Use the first extractant to extract the nickel sulfate stock solution F1, control the volume ratio of the two to be 2.4-2.6, control the extraction temperature to be 45-55℃ and the extraction time to be 3-5 min. After extraction, let it stand to clarify, and obtain the upper layer containing the first organic phase and the lower layer nickel sulfate solution F2 after the first impurity removal.

[0006] (2) Secondary extraction: The nickel sulfate solution F2 after the first impurity removal was extracted with a second extractant, and the volume ratio of the two was controlled at 2.7-2.9. The extraction temperature was controlled at 45-55℃ and the extraction time was controlled at 3-5 min. After extraction, the solution was allowed to stand and clarify to obtain the upper layer of impurity-containing second organic phase and the lower layer of nickel sulfate solution F3 after secondary impurity removal.

[0007] (3) Washing and back-extraction: While stirring, dilute hydrochloric acid is added to the impurity-containing second organic phase. After the solution changes color, the addition is stopped. After standing and separation, the second organic phase loaded with impurities and the first washing solution are obtained. Then, while stirring, dilute hydrochloric acid is added to the impurity-containing second organic phase until the aqueous phase turns slightly red. After standing and separation, the washed second organic phase and high-purity magnesium solution are obtained. The washed second organic phase is back-extracted with dilute hydrochloric acid to obtain a blank second organic phase and a high-purity cobalt solution.

[0008] (4) Three extractions: The nickel sulfate solution F3 after two impurity removals is extracted with a third extractant to obtain the final nickel sulfate solution.

[0009] Preferably, the preparation method of the first extractant in step (1) is as follows: First, P204 extractant and light white oil are mixed at a volume ratio of 1:(2.5-3.5) to obtain the first organic phase; then, liquid alkali is mixed with the first organic phase for saponification, and after clarification, the lower layer of saponification wastewater and the upper layer of saponified first organic phase are obtained; then, the saponified first organic phase is mixed with the first soap conversion liquid for soap conversion, and after clarification, the lower layer of soap conversion waste liquid and the upper layer of first extractant are obtained.

[0010] Preferably, the saponification value of the saponification in step (1) is 0.4-0.55 and the saponification time is 3-5 min; the soap transfer temperature is 45-55℃ and the soap transfer time is 3-5 min.

[0011] Preferably, the preparation method of the second extractant in step (2) is as follows: First, P507 extractant and light white oil are mixed at a volume ratio of 1:(2.5-3.5) to obtain the second organic phase; then, liquid alkali and the second organic phase are mixed and saponified, and after clarification, the lower layer of saponification wastewater and the upper layer of saponified second organic phase are obtained; then, the saponified second organic phase is mixed with the second soap conversion liquid for soap conversion, and after clarification, the lower layer of soap conversion waste liquid and the upper layer of second extractant are obtained.

[0012] Preferably, the saponification value of the saponification in step (2) is 0.4-0.55 and the saponification time is 3-5 min; the soap transfer temperature is 45-55℃ and the soap transfer time is 3-5 min.

[0013] Preferably, the third extractant in step (4) contains 272 extractant.

[0014] Preferably, the concentration of the dilute hydrochloric acid used for washing in step (3) is 2-3N, and the concentration of the dilute hydrochloric acid used for back-extraction is 5-6N.

[0015] Preferably, the process also includes step (5) regeneration of the first organic phase: First, while stirring, dilute hydrochloric acid with a concentration of 2-3N is added to the impurity-containing first organic phase. When the solution color changes, the process is stopped, and the phase is allowed to stand and separate into layers to obtain the upper washed first organic phase and the lower nickel washing solution. Then, the first organic phase is back-extracted and washed with dilute hydrochloric acid of 5-6N to obtain the first back-extraction solution and the blank first organic phase.

[0016] The beneficial effects of this invention are:

[0017] (1) The method disclosed in this invention first uses P204 extractant to extract nickel sulfate stock solution F1 once to remove Ca, Cu, Mn, and Zn impurities from F1, obtaining a purified nickel sulfate solution F2. Then, F2 is extracted with P507 extractant to obtain a second organic phase containing impurities and a second purified nickel sulfate solution F3. Finally, F3 solution is extracted three times to obtain the target product nickel sulfate solution and high-purity magnesium solution. The second organic phase containing impurities is washed twice. The purpose of the first wash is to remove nickel from the second organic phase containing impurities, and the purpose of the second wash is to remove Mg while avoiding the loss of Co. Then, the washed second organic phase is back-extracted to obtain a high-purity cobalt solution with very low impurity content. The method disclosed in this invention can simultaneously produce high-purity cobalt and high-purity magnesium solutions as byproducts while preparing nickel sulfate solution. The concentration of the nickel sulfate solution prepared using this method can reach above 140 g / L, and the total content of impurities such as Ca, Cu, Mn, Zn, Cr, Si, Pb, As, Al, and B in the nickel sulfate solution is less than 3 mg / L. The concentration of the high-purity cobalt solution (cobalt sulfate solution) can reach above 130 g / L, with the total content of impurities such as Ca, Cu, Mn, Zn, Cr, Si, Pb, As, Al, and B less than 3 mg / L. The concentration of the high-purity magnesium solution (magnesium sulfate solution) can reach above 50 g / L, with the total content of impurities such as Ca, Cu, Mn, and Zn less than 3 mg / L and the Co content less than 100 mg / L. Compared to traditional nickel sulfate preparation processes, the method disclosed in this invention has a more rational process design, is simpler to operate, and has lower production costs.

[0018] (2) The method disclosed in this invention involves saponifying P204 extractant and P507 extractant with light white oil, then converting the oil into soap using the corresponding soap conversion solution before extraction. The proportions and process parameters of the saponification and soap conversion process have been designed to maximize the selectivity of the extractant for impurities, thereby improving the extraction efficiency and avoiding the introduction of other impurities into the byproducts. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process flow of the method disclosed in this invention. Detailed Implementation

[0020] The following is in conjunction with the appendix Figure 1 The present invention will be described in detail below with reference to specific embodiments. The embodiments shown below are not intended to limit the scope of the invention as described in the claims. Furthermore, the complete contents of the configurations shown in the embodiments below are not limited to those necessary for the solution of the invention as described in the claims.

[0021] Example 1

[0022] A method for removing impurities from a nickel sulfate solution includes the following steps:

[0023] (1) First extraction: First, P204 extractant and light white oil are mixed at a volume ratio of 1:2.8 to obtain the first organic phase; then, liquid alkali is mixed with the first organic phase for saponification, with the saponification value controlled at 0.45 and the saponification time at 5 min. After clarification, the lower layer of saponification wastewater and the upper layer of saponified first organic phase are obtained; then, the saponified first organic phase is mixed with the first saponification solution for saponification, with the saponification temperature controlled at 48℃ and the saponification time at 5 min. After clarification, the lower layer of saponification wastewater and the upper layer of first extractant are obtained. Finally, the first extractant is used to extract nickel sulfate stock solution F1, with the volume ratio of the two controlled at 2.5, the extraction temperature controlled at 48℃ and the extraction time at 5 min. After extraction, the solution is allowed to stand and clarify to obtain the upper layer of impurity-containing first organic phase and the lower layer of nickel sulfate solution F2 after one purification.

[0024] (2) Secondary extraction: First, P507 extractant and light white oil are mixed at a volume ratio of 1:3 to obtain a second organic phase; then, liquid alkali and the second organic phase are mixed and saponified, with the saponification value controlled at 0.45 and the saponification time at 5 min. After clarification, a lower layer of saponification wastewater and an upper layer of saponified second organic phase are obtained; then, the saponified second organic phase is mixed with the second saponification solution for saponification, with the saponification temperature controlled at 48℃ and the saponification time at 5 min. After clarification, a lower layer of saponification wastewater and an upper layer of second extractant are obtained. Finally, the second extractant is used to extract the nickel sulfate solution F2 after the first impurity removal, with the volume ratio of the two controlled at 2.8, the extraction temperature controlled at 48℃ and the extraction time at 5 min. After extraction, the solution is allowed to stand and clarify, resulting in an upper layer of impurity-containing second organic phase and a lower layer of nickel sulfate solution F3 after the second impurity removal.

[0025] (3) Washing and back-extraction: While stirring, add 2.5N dilute hydrochloric acid to the impurity-containing second organic phase. Stop when the solution changes color. After standing and separating, the second organic phase loaded with impurities and the first washing solution are obtained. Then, while stirring, add dilute hydrochloric acid to the second organic phase loaded with impurities until the aqueous phase turns slightly red. After standing and separating, the washed second organic phase and high-purity magnesium solution are obtained. Back-extract the washed second organic phase with 5.5N dilute hydrochloric acid to obtain a blank second organic phase and a high-purity cobalt solution.

[0026] (4) Three-stage extraction: The nickel sulfate solution F3 after two impurity removals is extracted with a third extractant containing 272 extractant to obtain the final nickel sulfate solution.

[0027] (5) Regeneration of the first organic phase: First, while stirring, add dilute hydrochloric acid with a concentration of 2.5N to the first organic phase containing impurities. Stop when the solution color changes and let it stand to separate into layers to obtain the upper layer of washed first organic phase and the lower layer of nickel washing solution. Then, back-extract and wash the first organic phase with dilute hydrochloric acid of 5.5N to obtain the first back-extract solution and the blank first organic phase.

[0028] After testing, the concentration of the nickel sulfate solution prepared in this embodiment was 140 g / L, and the total content of impurities such as Ca, Cu, Mn, Zn, Cr, Si, Pb, As, Al, and B in the nickel sulfate solution was less than 3 mg / L; the concentration of the cobalt solution was 130 g / L, and the total content of impurities such as Ca, Cu, Mn, Zn, Cr, Si, Pb, As, Al, and B in the cobalt solution (cobalt sulfate solution) was less than 3 mg / L; the concentration of the magnesium solution (magnesium sulfate solution) was 50 g / L, and the total content of impurities such as Ca, Cu, Mn, and Zn in the magnesium solution was less than 3 mg / L, and the Co content was less than 100 mg / L.

[0029] Example 2

[0030] A method for removing impurities from a nickel sulfate solution includes the following steps:

[0031] (1) First extraction: First, P204 extractant and light white oil are mixed at a volume ratio of 1:2.5 to obtain the first organic phase; then, liquid alkali is mixed with the first organic phase for saponification, with the saponification value controlled at 0.4 and the saponification time at 3 min. After clarification, the lower layer of saponification wastewater and the upper layer of saponified first organic phase are obtained; then, the saponified first organic phase is mixed with the first saponification solution for saponification, with the saponification temperature controlled at 45℃ and the saponification time at 3 min. After clarification, the lower layer of saponification wastewater and the upper layer of first extractant are obtained. Finally, the first extractant is used to extract nickel sulfate stock solution F1, with the volume ratio of the two controlled at 2.4, the extraction temperature controlled at 45℃ and the extraction time at 3 min. After extraction, the solution is allowed to stand and clarify to obtain the upper layer of impurity-containing first organic phase and the lower layer of nickel sulfate solution F2 after one purification.

[0032] (2) Secondary extraction: First, P507 extractant and light white oil are mixed at a volume ratio of 1:2.5 to obtain a second organic phase; then, liquid alkali and the second organic phase are mixed and saponified, with the saponification value controlled at 0.4 and the saponification time at 3 min. After clarification, a lower layer of saponification wastewater and an upper layer of saponified second organic phase are obtained; then, the saponified second organic phase is mixed with the second saponification solution for saponification, with the saponification temperature controlled at 45℃ and the saponification time at 3 min. After clarification, a lower layer of saponification wastewater and an upper layer of second extractant are obtained. Finally, the second extractant is used to extract the nickel sulfate solution F2 after the first impurity removal, with the volume ratio of the two controlled at 2.7, the extraction temperature controlled at 45℃ and the extraction time at 3 min. After extraction, the solution is allowed to stand and clarify, resulting in an upper layer of impurity-containing second organic phase and a lower layer of nickel sulfate solution F3 after the second impurity removal.

[0033] (3) Washing and back-extraction: While stirring, add dilute hydrochloric acid with a concentration of 2N to the impurity-containing second organic phase. Stop when the solution changes color. After standing and separating, obtain the second organic phase loaded with impurities and the first washing solution. Then, while stirring, add dilute hydrochloric acid to the second organic phase loaded with impurities until the aqueous phase turns slightly red. After standing and separating, obtain the washed second organic phase and high-purity magnesium solution. Back-extract the washed second organic phase with dilute hydrochloric acid with a concentration of 5N to obtain the blank second organic phase and high-purity cobalt solution.

[0034] (4) Three-stage extraction: The nickel sulfate solution F3 after two impurity removals is extracted with a third extractant containing 272 extractant to obtain the final nickel sulfate solution.

[0035] (5) Regeneration of the first organic phase: First, while stirring, add dilute hydrochloric acid with a concentration of 2N to the impurity-containing first organic phase. Stop when the solution color changes and let it stand to separate into layers to obtain the upper washed first organic phase and the lower nickel washing solution. Then, back-extract and wash the first organic phase with dilute hydrochloric acid of 5N to obtain the first back-extract solution and the blank first organic phase.

[0036] After testing, the concentration of the nickel sulfate solution prepared in this embodiment was 138 g / L, and the total content of impurities such as Ca, Cu, Mn, Zn, Cr, Si, Pb, As, Al, and B in the nickel sulfate solution was less than 2 mg / L; the concentration of the cobalt solution was above 131 g / L, and the total content of impurities such as Ca, Cu, Mn, Zn, Cr, Si, Pb, As, Al, and B in the cobalt solution (cobalt sulfate solution) was less than 2.5 mg / L; the concentration of the magnesium solution (magnesium sulfate solution) was above 51.5 g / L, and the total content of impurities such as Ca, Cu, Mn, and Zn in the magnesium solution was less than 2.7 mg / L, and the Co content was 80 mg / L.

[0037] Example 3

[0038] A method for removing impurities from a nickel sulfate solution includes the following steps:

[0039] (1) First extraction: First, P204 extractant and light white oil are mixed at a volume ratio of 1:3.5 to obtain the first organic phase; then, liquid alkali is mixed with the first organic phase for saponification, with the saponification value controlled at 0.55 and the saponification time at 5 min. After clarification, the lower layer of saponification wastewater and the upper layer of saponified first organic phase are obtained; then, the saponified first organic phase is mixed with the first saponification solution for saponification, with the saponification temperature controlled at 55℃ and the saponification time at 5 min. After clarification, the lower layer of saponification wastewater and the upper layer of first extractant are obtained. Finally, the first extractant is used to extract nickel sulfate stock solution F1, with the volume ratio of the two controlled at 2.6, the extraction temperature controlled at 55℃ and the extraction time at 5 min. After extraction, the solution is allowed to stand and clarify to obtain the upper layer of impurity-containing first organic phase and the lower layer of nickel sulfate solution F2 after one purification.

[0040] (2) Secondary extraction: First, P507 extractant and light white oil are mixed at a volume ratio of 1:3.5 to obtain a second organic phase; then, liquid alkali and the second organic phase are mixed and saponified, with the saponification value controlled at 0.55 and the saponification time at 5 min. After clarification, a lower layer of saponification wastewater and an upper layer of saponified second organic phase are obtained; then, the saponified second organic phase is mixed with the second saponification solution for saponification, with the saponification temperature controlled at 55℃ and the saponification time at 5 min. After clarification, a lower layer of saponification wastewater and an upper layer of second extractant are obtained. Finally, the second extractant is used to extract the nickel sulfate solution F2 after the first impurity removal, with the volume ratio of the two controlled at 2.9, the extraction temperature controlled at 55℃ and the extraction time at 5 min. After extraction, the solution is allowed to stand and clarify, resulting in an upper layer of impurity-containing second organic phase and a lower layer of nickel sulfate solution F3 after the second impurity removal.

[0041] (3) Washing and back-extraction: While stirring, add 3N dilute hydrochloric acid to the impurity-containing second organic phase. Stop when the solution changes color. After standing and separating, obtain the second organic phase loaded with impurities and the first washing solution. Then, while stirring, add dilute hydrochloric acid to the second organic phase loaded with impurities until the aqueous phase turns slightly red. After standing and separating, obtain the washed second organic phase and high-purity magnesium solution. Back-extract the washed second organic phase with 6N dilute hydrochloric acid to obtain the blank second organic phase and high-purity cobalt solution.

[0042] (4) Three-stage extraction: The nickel sulfate solution F3 after two impurity removals is extracted with a third extractant containing 272 extractant to obtain the final nickel sulfate solution.

[0043] (5) Regeneration of the first organic phase: First, while stirring, add dilute hydrochloric acid with a concentration of 3N to the first organic phase containing impurities. Stop when the solution color changes and let it stand to separate into layers to obtain the upper layer of washed first organic phase and the lower layer of nickel washing solution. Then, back-extract and wash the first organic phase with dilute hydrochloric acid of 6N to obtain the first back-extract solution and the blank first organic phase.

[0044] After testing, the concentration of the nickel sulfate solution prepared in this embodiment was 137 g / L, and the total content of impurities such as Ca, Cu, Mn, Zn, Cr, Si, Pb, As, Al, and B in the nickel sulfate solution was less than 1.5 mg / L; the concentration of the cobalt solution was 126 g / L, and the total content of impurities such as Ca, Cu, Mn, Zn, Cr, Si, Pb, As, Al, and B in the cobalt solution (cobalt sulfate solution) was less than 2 mg / L; the concentration of the magnesium solution (magnesium sulfate solution) was above 48 g / L, and the total content of impurities such as Ca, Cu, Mn, and Zn in the magnesium solution was less than 2.3 mg / L, and the Co content was 55 mg / L.

[0045] Example 4

[0046] A method for removing impurities from a nickel sulfate solution includes the following steps:

[0047] (1) First extraction: First, P204 extractant and light white oil are mixed at a volume ratio of 1:3 to obtain the first organic phase; then, liquid alkali is mixed with the first organic phase for saponification, with the saponification value controlled at 0.5 and the saponification time at 4 min. After clarification, the lower layer of saponification wastewater and the upper layer of saponified first organic phase are obtained; then, the saponified first organic phase is mixed with the first saponification solution for saponification, with the saponification temperature controlled at 50℃ and the saponification time at 4 min. After clarification, the lower layer of saponification wastewater and the upper layer of first extractant are obtained. Finally, the first extractant is used to extract nickel sulfate stock solution F1, with the volume ratio of the two controlled at 2.5, the extraction temperature controlled at 50℃ and the extraction time at 4 min. After extraction, the solution is allowed to stand and clarify to obtain the upper layer of impurity-containing first organic phase and the lower layer of nickel sulfate solution F2 after one purification.

[0048] (2) Secondary extraction: First, P507 extractant and light white oil are mixed at a volume ratio of 1:3 to obtain the second organic phase; then, liquid alkali and the second organic phase are mixed and saponified, with the saponification value controlled at 0.5 and the saponification time at 4 min. After clarification, the lower layer of saponification wastewater and the upper layer of saponified second organic phase are obtained; then, the saponified second organic phase is mixed with the second saponification solution for saponification, with the saponification temperature controlled at 50℃ and the saponification time at 4 min. After clarification, the lower layer of saponification wastewater and the upper layer of second extractant are obtained. Finally, the nickel sulfate solution F2 after the first impurity removal is extracted with the second extractant, with the volume ratio of the two controlled at 2.8, the extraction temperature controlled at 50℃ and the extraction time at 4 min. After extraction, the solution is allowed to stand and clarify, with the upper layer of impurity-containing second organic phase and the lower layer of nickel sulfate solution F3 after the second impurity removal are obtained.

[0049] (3) Washing and back-extraction: While stirring, add 2.5N dilute hydrochloric acid to the impurity-containing second organic phase. Stop when the solution changes color. After standing and separating, the second organic phase loaded with impurities and the first washing solution are obtained. Then, while stirring, add dilute hydrochloric acid to the second organic phase loaded with impurities until the aqueous phase turns slightly red. After standing and separating, the washed second organic phase and high-purity magnesium solution are obtained. Back-extract the washed second organic phase with 5.5N dilute hydrochloric acid to obtain a blank second organic phase and a high-purity cobalt solution.

[0050] (4) Three-stage extraction: The nickel sulfate solution F3 after two impurity removals is extracted with a third extractant containing 272 extractant to obtain the final nickel sulfate solution.

[0051] (5) Regeneration of the first organic phase: First, while stirring, add dilute hydrochloric acid with a concentration of 2.5N to the first organic phase containing impurities. Stop when the solution color changes and let it stand to separate into layers to obtain the upper layer of washed first organic phase and the lower layer of nickel washing solution. Then, back-extract and wash the first organic phase with dilute hydrochloric acid of 5.5N to obtain the first back-extract solution and the blank first organic phase.

[0052] After testing, the concentration of the nickel sulfate solution prepared in this embodiment was above 142 g / L, and the total content of impurities such as Ca, Cu, Mn, Zn, Cr, Si, Pb, As, Al, and B in the nickel sulfate solution was less than 2.2 mg / L; the concentration of the cobalt solution was 133 g / L, and the total content of impurities such as Ca, Cu, Mn, Zn, Cr, Si, Pb, As, Al, and B in the cobalt solution (cobalt sulfate solution) was less than 1.8 mg / L; the concentration of the magnesium solution (magnesium sulfate solution) was 49 g / L, and the total content of impurities such as Ca, Cu, Mn, and Zn in the magnesium solution was less than 2 mg / L, and the Co content was 50 mg / L.

[0053] Example 5

[0054] Reference Appendix Figure 1 This embodiment describes the method described in this invention in conjunction with an actual production line.

[0055] The parameters of the nickel raw material used in the example are as follows: Ni content 99.10 g / L, Co content 5.25 g / L, Mg content 5.73 g / L, Ca 36.27 mg / L, Cu 231.39 mg / L, Mn 8.69 g / L, Zn 1 g / L, pH value 3.19; P204 line mixing chamber 2000L, clarification chamber 3200*1200*1550; P507 clarification chamber 2000L, clarification chamber 3700*1200*1550.

[0056] (1) NiP204 line except Ca, Cu, Mn and Zn

[0057] When the production line is running, 0.5m 3 / h of liquid alkali with 14.8m 3 The organic solution in stage A1 undergoes saponification at a flow rate of / h, while the flow rate of the soap-converting solution in stage A7 is 0.1m³. 3 / h, feed flow rate 6m 3 / h, after impurity removal in the extraction section and concentration enhancement in the soap conversion section, the impurity-laden organic phase moves from the extraction section to the washing section. The impurities such as Ca, Cu, Mn, and Zn in the raffinate are basically below 1 mg / L. The size of the soap conversion solution is carefully controlled based on the cobalt concentration and aqueous phase color in the raffinate. The acid washing flow rate is adjusted in a timely manner according to the impurity content in the raw material. The acid washing solution is not discharged and moves from the washing section to the extraction section. If the workshop has a process to treat this washing solution, it can be discharged. To a certain extent, the washing solution will affect the Ni concentration in the raffinate. The acid backflow is also adjusted in a timely manner according to the Mn content in the raw material and the reflux degree of the backflow section. The resulting backflow solution is manganese solution with an Mn content fluctuating around 100 g / L. The organic phase, after passing through the last stage of the backflow section, is washed with concentrated hydrochloric acid and pure water and then enters the intermediate transfer tank for recycling.

[0058] (2) Separation of Co and Mg using NiP507

[0059] The residue from NiP204 raffinate is called F2. At this point, F2 enters the NiP507 line, and the liquid alkali flow rate is 0.86 m³ / h. 3 / h, organic 16m 3 / h, soap conversion solution approximately 2.5m 3 / h, liquid feed 6m 3 The process involves countercurrent extraction to remove Co and Mg impurities from F2, yielding raffinate F3 in the extraction section. At this stage, the Co content is 0.01 mg / L, and the Mg content ranges from 1.5 to 4.5 mg / L, exhibiting significant fluctuations. The washing section is divided into two parts, both using 5.5–6.0 N dilute sulfuric acid. The first part is the nickel washing section, where both the Ni washing acid and washing water flow rates are 0.5 m³ / h. 3 / h, followed by the Mg washing section, where the Mg washing acid flow rate and the washing water flow rate are both 0.4m³ / h. 3 / h and 0.8m 3 / h, it is worth noting that acid washing needs to be adjusted in a timely manner according to the color band, especially for washing Mg acid. If the feed impurity fluctuates greatly, timely adjustment is required. This is the key to whether NiP507 can be operated well, and frequent inspections and timely adjustments are necessary; the back-extraction section acid back-extraction is 0.35m 3 / h, the back-extraction solution is cobalt sulfate, and the concentration can reach 90-130g / L. Sometimes, due to the failure to control the washing of Mg acid well, impurities such as Mg may exceed the standard slightly.

[0060] (2) NiC272 cleanroom line and CoP204 cleanroom line

[0061] The NiC272 purification line and the CoP204 purification line are the final guarantee for nickel sulfate and cobalt sulfate solutions, respectively, to prevent substandard nickel sulfate and cobalt sulfate from being produced due to sudden or accidental operational errors in the finished product line.

[0062] After testing, the purity of the nickel sulfate solution prepared in this embodiment was 97.73%; the purity of the cobalt solution was 93.8%; and the purity of the magnesium solution was 90.61%.

[0063] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for removing impurities from a nickel sulfate solution, characterized in that, Includes the following steps: (1) First extraction: The nickel sulfate stock solution F1 is extracted using the first extractant, with the volume ratio of the two controlled at 2.4-2.6, the extraction temperature controlled at 45-55℃, and the extraction time controlled at 3-5 min. After extraction, the solution is allowed to stand and clarify to obtain the upper layer containing the first organic phase and the lower layer of nickel sulfate solution F2 after the first impurity removal. The preparation method of the first extractant is as follows: First, P204 extractant and light white oil are mixed at a volume ratio of 1:(2.5-3.5) to obtain the first organic phase. Then, liquid alkali is mixed with the first organic phase for saponification. After clarification, the lower layer of saponification wastewater and the upper layer of saponified first organic phase are obtained. Then, the saponified first organic phase is mixed with the first soap conversion solution for soap conversion. After clarification, the lower layer of soap conversion wastewater and the upper layer of first extractant are obtained. (2) Secondary extraction: The nickel sulfate solution F2 after the first impurity removal is extracted with a second extractant, and the volume ratio of the two is controlled at 2.7-2.

9. The extraction temperature is controlled at 45-55℃ and the extraction time is controlled at 3-5 min. After extraction, the solution is allowed to stand and clarify to obtain the upper layer of impurity-containing second organic phase and the lower layer of nickel sulfate solution F3 after secondary impurity removal. The preparation method of the second extractant is as follows: First, P507 extractant and light white oil are mixed at a volume ratio of 1:(2.5-3.5) to obtain the second organic phase. Then, liquid alkali and the second organic phase are mixed and saponified. After clarification, the lower layer of saponification wastewater and the upper layer of saponified second organic phase are obtained. Then, the saponified second organic phase is mixed with the second saponification solution for saponification. After clarification, the lower layer of saponification wastewater and the upper layer of second extractant are obtained. (3) Washing and back-extraction: While stirring, dilute hydrochloric acid is added to the impurity-containing second organic phase. After the solution changes color, the addition is stopped. After standing and separation, the second organic phase loaded with impurities and the first washing solution are obtained. Then, while stirring, dilute hydrochloric acid with a concentration of 2-3N is added to the second organic phase loaded with impurities until the aqueous phase turns slightly red. After standing and separation, the washed second organic phase and high-purity magnesium solution are obtained. The washed second organic phase is back-extracted using dilute hydrochloric acid with a concentration of 5-6N to obtain a blank second organic phase and a high-purity cobalt solution. (4) Three extractions: The nickel sulfate solution F3 after the second impurity removal was extracted with a third extractant to obtain the final nickel sulfate solution; the third extractant contains C272 extractant.

2. The method for removing impurities from a nickel sulfate solution according to claim 1, characterized in that, The saponification value of the saponification in step (1) is 0.4-0.55 and the saponification time is 3-5 min; the soap transfer temperature is 45-55℃ and the soap transfer time is 3-5 min.

3. The method for removing impurities from a nickel sulfate solution according to claim 1, characterized in that, The saponification value of the saponification in step (2) is 0.4-0.55 and the saponification time is 3-5 min; the soap transfer temperature is 45-55℃ and the soap transfer time is 3-5 min.

4. The method for removing impurities from a nickel sulfate solution according to claim 1, characterized in that, It also includes step (5) regeneration of the first organic phase: First, while stirring, dilute hydrochloric acid with a concentration of 2-3N is added to the impurity-containing first organic phase. When the solution color changes, stop and let it stand to separate into layers to obtain the upper washed first organic phase and the lower nickel washing solution; then the first organic phase is back-extracted and washed with dilute hydrochloric acid of 5-6N to obtain the first back-extraction solution and the blank first organic phase.

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