Method for deep oil removal of nickel sulfate solution resin

Abstract

The present application relates to a kind of methods for deep oil removal of nickel sulfate solution resin, comprising the following steps: S1 oil removal resin pretreatment: select modified polystyrene-divinylbenzene macroporous adsorption resin as oil removal resin, and sequentially carry out acid dipping, deionized water washing, obtain pretreatment oil removal resin;S2 nickel sulfate solution pretreatment: the nickel sulfate solution to be treated is filtered by precision filter;S3 resin column deep oil removal: the obtained filtrate is imported into the fixed bed resin column loaded with pretreatment oil removal resin and is adsorbed;S4 hot water regeneration of oil removal resin: 80~90 ℃ deionized water is used as regenerant to reverse flush saturated resin column, and the oil-containing hot water generated during regeneration is collected as regeneration waste liquid;After regeneration, the resin column is washed with 30~40 ℃ deionized water until the adsorption capacity is restored;S5 regeneration waste liquid treatment: regeneration waste liquid is separated by oil and water, and the water phase is recycled after cooling. The present application not only ensures the depth of oil removal, but also realizes the green process and low-cost operation.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical solution purification technology, and in particular to a method for deep oil removal from nickel sulfate solution using resin. Background Technology

[0002] Nickel sulfate, a core raw material for ternary lithium-ion battery cathode materials, directly determines the battery's electrochemical performance and cycle life. During the preparation of nickel sulfate solutions (such as nickel ore leaching and waste nickel resource recycling), oily impurities such as fatty acids, esters, and organic amines can easily be introduced due to factors like raw material carryover, extractant degradation, or equipment lubricant leakage. If these impurities are not effectively removed, they can lead to pinholes and peeling on the nickel product surface during subsequent electrolytic deposition, or the formation of agglomerates during cathode material synthesis, severely affecting product quality.

[0003] Existing nickel sulfate solution degreasing processes typically employ physical adsorption, solvent extraction, membrane separation, and traditional resin methods, but these methods have varying degrees of technical drawbacks: Physical adsorption method: Oil removal using adsorbents such as activated carbon and diatomaceous earth requires frequent replacement of the adsorbent, and the adsorbent has poor selectivity for low molecular weight oily impurities, with the oil removal depth only reaching below 5 mg / L, which cannot meet the requirements of battery-grade nickel sulfate for oily impurities (requirement ≤0.5 mg / L); Solvent extraction: This method involves adding organic solvents to back-extract oily impurities, which can easily introduce new organic pollutants and result in solvent evaporation losses, increasing production costs and environmental risks. Membrane separation method: When using ultrafiltration and nanofiltration membranes to remove oil, the membrane modules are easily clogged by oily impurities, requiring frequent chemical cleaning, which shortens the membrane life (usually ≤6 months) and results in high equipment investment costs; Traditional resin method: Existing technologies mostly use ordinary macroporous adsorption resins, which require the use of organic reagents such as methanol and ethanol for regeneration. This poses a risk of organic reagent residues, and the regeneration process is energy-intensive and complex, making it difficult to achieve continuous industrial operation. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for deep degreasing of nickel sulfate solution resin to achieve green process and low-cost operation.

[0005] To solve the above problems, the present invention provides a method for deep degreasing with nickel sulfate solution resin, comprising the following steps: S1 degreasing resin pretreatment: Modified polystyrene-divinylbenzene macroporous adsorption resin was selected as the degreasing resin, and it was subjected to acid leaching and deionized water rinsing until pH=3.5~4.5 to obtain the pretreated degreasing resin. S2 nickel sulfate solution pretreatment: The nickel sulfate solution to be treated is filtered through a precision filter, and the temperature of the resulting filtrate is controlled at 30~40℃; S3 resin column deep degreasing: The resulting filtrate is passed into a fixed-bed resin column packed with pretreated degreasing resin at a flow rate of 1~3 BV / h, and adsorbed at 30~40℃. The content of oily impurities in the outlet solution is monitored to obtain the treated nickel sulfate solution. Hot water regeneration of S4 degreasing resin: The resin column under saturation was backwashed with deionized water at 80-90℃ as a regenerator, and the oily hot water generated during the regeneration process was collected as regeneration waste liquid. After regeneration, the resin column was rinsed with deionized water at 30-40℃ until the adsorption capacity was restored. S5 Regenerated Waste Liquid Treatment: The recycled waste liquid is separated into oil and water, and the aqueous phase is cooled to 30~40℃ before being returned to step S2 for recycling.

[0006] In step S1, the modified polystyrene-divinylbenzene macroporous adsorption resin is grafted with hydroxyl (-OH) and carboxyl (-COOH) functional groups on its surface; the resin has a particle size of 0.3~0.8 mm and a specific surface area of ​​800~1200 m². 2 / g, with a pore volume of 0.8~1.2mL / g.

[0007] In step S1, acid immersion refers to soaking in a 5% sulfuric acid solution for 2 hours.

[0008] In step S2, the Ni in the nickel sulfate solution to be treated 2+ The concentration is 50~80g / L, pH=2.0~3.0, and the content of oily impurities is 5~20mg / L.

[0009] The precision filter in step S2 has a filtration accuracy of 5 μm.

[0010] In step S3, the resin column diameter-to-height ratio is 1:8 to 1:12; when the oily impurity content of the outlet solution is between 0.45 and 0.50 mg / L, the liquid feeding is stopped.

[0011] The oily impurity content of the nickel sulfate solution after treatment in step S3 is ≤0.5mg / L.

[0012] In step S4, the regeneration flow rate is 2~4 BV / h and the time is 1.5~2.5h; the rinsing flow rate is 1~2 BV / h and the time is 1~1.5h.

[0013] The conditions for oil-water separation in step S5 are a temperature of 70~80℃ and standing for 2~3 hours to separate the layers.

[0014] The modified polystyrene-divinylbenzene macroporous adsorption resin in step S1 is recycled ≥50 times.

[0015] Compared with the prior art, the present invention has the following advantages: 1. High degreasing depth: The present invention uses a modified functionalized resin, which has an adsorption rate of ≥97% for oily impurities in nickel sulfate solution, and the content of oily impurities in the treated solution is ≤0.5mg / L, which meets the purity requirements of battery-grade nickel sulfate.

[0016] 2. The recycling method is green and environmentally friendly: This invention uses hot water as a regenerator, eliminating the need for organic reagents such as methanol and ethanol, thus avoiding organic reagent residues and volatilization pollution, and ensuring no secondary pollution during the regeneration process.

[0017] 3. Long resin life: The hot water regeneration process in this invention is gentle and will not damage the resin skeleton structure and functional groups. The resin can be recycled ≥50 times, and its service life is extended to 2~3 years, reducing the cost of resin replacement.

[0018] 4. Strong process continuity: The regeneration process in this invention only requires hot water and deionized water, is simple to operate, and can realize online regeneration and switching of resin columns, making it suitable for industrial continuous production.

[0019] 5. Low energy consumption and low cost: In this invention, the regenerated hot water can be heated by waste heat from the factory, and the aqueous phase in the regenerated waste liquid can be recycled, reducing energy consumption and water resource consumption. The overall treatment cost is reduced by 30% to 40% compared with the traditional resin method. Detailed Implementation

[0020] A method for deep degreasing with nickel sulfate solution resin includes the following steps: S1 degreasing resin pretreatment: Modified polystyrene-divinylbenzene macroporous adsorption resin was selected as the degreasing resin. It was first soaked in a 5% sulfuric acid solution for 2 hours to remove residual monomers and impurities on the resin surface, and then rinsed with deionized water until the pH was 3.5~4.5, thus obtaining the pretreated degreasing resin.

[0021] Among them, the modified polystyrene-divinylbenzene macroporous adsorption resin has hydroxyl (-OH) and carboxyl (-COOH) functional groups grafted onto its surface, enhancing its selective adsorption capacity for oily impurities; the resin has a particle size of 0.3~0.8mm and a specific surface area of ​​800~1200m². 2 / g, with a pore volume of 0.8~1.2mL / g.

[0022] The modified polystyrene-divinylbenzene macroporous adsorption resin is DuPont™ AmberLite™ XAD™ 16N polymer adsorption resin.

[0023] S2 nickel sulfate solution pretreatment: The nickel sulfate solution to be treated is filtered through a precision filter with a filtration accuracy of 5μm to remove suspended particulate matter from the solution and prevent particulate matter from clogging the resin pores; and the temperature of the resulting filtrate is controlled at 30~40℃.

[0024] Among them: Ni in the nickel sulfate solution to be treated 2+ The concentration is 50~80g / L, pH=2.0~3.0, and the content of oily impurities is 5~20mg / L.

[0025] S3 resin column deep degreasing: The resulting filtrate is fed into a fixed-bed resin column packed with pretreated degreasing resin at a flow rate of 1–3 BV / h (bed volume / hour), with a column diameter-to-height ratio of 1:8–1:12. Adsorption occurs at 30–40 °C. The hydroxyl and carboxyl functional groups on the resin surface selectively adsorb oily impurities from the solution through hydrogen bonding and van der Waals forces. The oily impurity content of the solution at the resin column outlet is monitored in real time using an online oil analyzer. When the oily impurity content of the outlet solution is between 0.45–0.50 mg / L, the feed is stopped, and the resin column reaches saturation, yielding the treated nickel sulfate solution. The oily impurity content of the treated nickel sulfate solution is ≤0.5 mg / L.

[0026] Hot water regeneration of S4 degreasing resin: The saturated resin column is backwashed for 1.5 to 2.5 hours with deionized water at 80-90℃ as the regenerator at a flow rate of 2-4 BV / h. During the regeneration process, the hot water breaks the hydrogen bonds between the resin and the oily impurities, causing the oily impurities to desorb and flow out with the hot water. The oily hot water generated during the regeneration process is collected as regeneration waste liquid (oily impurity content is 100-300 mg / L). After regeneration, the resin column is forward-washed with deionized water at 30-40℃ at a flow rate of 1-2 BV / h for 1-1.5 hours until the temperature of the washing liquid drops to 35-40℃, and the resin column regains its adsorption capacity and can re-enter the oil removal cycle.

[0027] S5 Regenerated Waste Liquid Treatment: The recycled waste liquid is fed into an oil-water separator and allowed to stand at 70-80℃ for 2-3 hours to separate into oil and water phases. The separated oil phase is collected and treated as hazardous waste, while the water phase is cooled to 30-40℃ and returned to step S2 for recycling, thus realizing the recycling of water resources.

[0028] The modified polystyrene-divinylbenzene macroporous adsorption resin in this invention can be recycled ≥50 times.

[0029] Example 1 A method for deep degreasing with nickel sulfate solution resin, comprising the following steps: S1 degreasing resin pretreatment: The modified polystyrene-divinylbenzene macroporous adsorption resin was soaked in 5% sulfuric acid solution for 2 hours and then rinsed with deionized water until pH=4.0.

[0030] S2 nickel sulfate solution pretreatment: Nickel sulfate solution to be treated: Ni 2+ Concentration 65g / L, pH=2.5, oily impurity content 12mg / L; filtered through a 5μm precision filter, temperature controlled at 35℃.

[0031] S3 resin column deep degreasing: The resin column diameter-to-height ratio was 1:10, the solution flow rate was 2 BV / h, and the temperature was 35℃. The content of oily impurities in the outlet solution was monitored online. After 8 hours of operation, the outlet content rose to 0.5 mg / L, and the inlet was stopped.

[0032] Hot water regeneration of S4 degreasing resin: The resin was regenerated using 85℃ deionized water at a reverse flow rate of 3 BV / h for 2 hours; then it was rinsed with 35℃ deionized water in the forward direction for 1.2 hours to restore its adsorption capacity.

[0033] S5 Regenerated Waste Liquid Treatment: The recycled waste liquid contained 220 mg / L of oily impurities. After standing at 75°C for 2.5 h, the phases separated. The oil phase was collected, and the aqueous phase was cooled to 35°C and returned to step S2 for reuse.

[0034] Results: The oil impurity content of the nickel sulfate solution after treatment was 0.42 mg / L, the resin regeneration rate was 98.5%, and the degreasing effect did not decrease significantly after 50 consecutive cycles.

[0035] Example 2: Verification of degreasing effect S1 degreasing resin pretreatment: The modified polystyrene-divinylbenzene macroporous adsorption resin was immersed in a 5% sulfuric acid solution for 2 hours, with stirring every 30 minutes during the process. It was then rinsed with deionized water until the pH of the rinsing solution reached 3.8, thus completing the pretreatment. S2 nickel sulfate solution pretreatment: The nickel sulfate solution to be treated originated from the recycling process of waste ternary lithium batteries, in which Ni... 2+ The concentration was 55 g / L, pH=2.2, and the oily impurity content was 18 mg / L (mainly phosphate ester impurities produced by the degradation of the extractant). After filtration through a 5 μm precision filter, the solution temperature was controlled at 32℃ by a plate heat exchanger.

[0036] S3 resin column deep degreasing: The resin column diameter-to-height ratio is 1:9, and the liquid inlet is top-inlet and bottom-outlet. The solution flow rate is 1.5 BV / h, and the adsorption temperature is maintained at 32℃. The content of oily impurities in the outlet solution is detected by offline sampling (sampling once every 1 hour) combined with an infrared oil separator. After 10 hours of operation, the outlet content rises to 0.48 mg / L, and the liquid inlet is stopped. Hot water regeneration of S4 degreasing resin: Deionized water at 82℃ (prepared by heating steam condensate from the factory) was reverse-flowed into the resin column at a flow rate of 2.5 BV / h for 2.2 h of regeneration. During the later stage of regeneration (the last 30 min), the flow rate was reduced to 1.5 BV / h to enhance the contact rate between the hot water and the resin. After regeneration, the resin was forward-washed with deionized water at 32℃ for 1.3 h. The pH of the wash solution stabilized at 3.9, and the resin regained its adsorption capacity. S5 Regenerated Waste Liquid Treatment: The oily impurity content of the recycled waste liquid was 280 mg / L. It was passed into an oil-water separator with stirring function and stirred at low speed (50 r / min) for 10 min at 72℃. After standing for 2.8 h, the stratification effect was better than that of static stratification. After separation, the oil phase accounted for 0.8% of the volume. The water phase was cooled to 32℃ and returned to step S2 as makeup water for solution pretreatment. The single reuse rate reached 85%. Results: The oily impurity content of the treated nickel sulfate solution was 0.45 mg / L, the resin regeneration rate was 99.0%, and after 45 consecutive cycles, the oily impurity content of the outlet solution was still ≤0.5 mg / L, making it suitable for treating recycled nickel sulfate solutions with high impurity content. Example 3: Optimization of degreasing process for high nickel concentration solutions S1 degreasing resin pretreatment: During pretreatment, the resin was soaked in sulfuric acid solution for 2.5 hours and rinsed with deionized water until the pH reached 4.2 to enhance the resin's tolerance to high nickel ion environments.

[0037] S2 nickel sulfate solution pretreatment: The nickel sulfate solution to be treated is a high-nickel leaching solution, Ni 2+ Concentration 78 g / L (close to saturation concentration), pH=2.8, oily impurity content 9 mg / L (mainly mineral oil). Due to the high viscosity of the solution, the filtration accuracy of the precision filter was adjusted to 3μm to prevent the viscous solution from clogging the filter membrane; the solution temperature was controlled at 38℃ by jacket heating to reduce the solution viscosity and improve the resin adsorption efficiency. S3 resin column deep degreasing: The resin column diameter-to-height ratio is 1:12, and a bottom-in, top-out liquid inlet method is adopted (to reduce the retention of high-concentration solutions in the resin column). The solution flow rate is 2.8 BV / h, and the adsorption temperature is 38℃. The online oil analyzer is set to monitor once every 30 minutes. After running for 7 hours, the oil impurity content of the outlet solution rises to 0.49 mg / L, and the liquid inlet is stopped. Hot water regeneration of S4 degreasing resin: Deionized water at 88℃ was used, with a reverse flow rate of 3.5 BV / h and a regeneration time of 1.8h. During the regeneration process, the oily impurity content of the regenerated solution was checked every 40 minutes. When the oily impurity content of the regenerated solution was ≤0.05mg / L, the regeneration was stopped 15 minutes earlier to avoid excessive energy consumption. After regeneration, the solution was rinsed with deionized water at 38℃ for 1.0h in the forward direction, and the rinsing solution volume was controlled at 2 BV (to reduce the dilution of high-nickel solution). S5 Regenerated Waste Liquid Treatment: The recycled waste liquid contains 150 mg / L of oily impurities. Because the solution contains a small amount of nickel ions, after oil-water separation, the aqueous phase is first passed through a cation exchange resin (model 001×7) to remove the nickel. 2+ (Removal rate ≥ 99%), then cool to 38°C and return to step S2 for reuse to avoid nickel ion accumulation. Treatment results: After treatment, the oily impurity content of the nickel sulfate solution was 0.47 mg / L, Ni 2+ With a loss rate of ≤0.1% (far lower than the industry standard of 0.5%), it solves the problems of high viscosity and nickel loss during the degreasing of high-concentration nickel solutions. Example 4: Application of low-energy regeneration technology (waste heat utilization scenario) S1 degreasing resin pretreatment: During pretreatment, the resin was soaked in sulfuric acid solution for 2.5 hours and rinsed with deionized water until pH=4.2. After pretreatment, it was soaked in deionized water at 35℃ for 1 hour to raise the resin temperature to near the adsorption temperature in advance and reduce subsequent solution temperature fluctuations.

[0038] S2 nickel sulfate solution pretreatment: Ni sulfate solution to be treated 2+ The concentration is 62 g / L, pH=2.6, and the oily impurity content is 11 mg / L. The solution temperature is preheated to 35°C using the waste heat from the leaching process, eliminating the need for additional heating and reducing energy consumption. S3 resin column deep degreasing: The resin column diameter-to-height ratio was 1:10, the solution flow rate was 2.2 BV / h, and the adsorption temperature was 35℃ (matched with the waste heat preheating temperature). After 8.5 hours of operation, the oily impurity content of the outlet solution rose to 0.46 mg / L, and the liquid feeding was stopped.

[0039] Hot water regeneration of S4 degreasing resin: The reclaimed water uses hot water heated by waste heat from the factory steam (temperature 79℃, 1℃ lower than the lower limit of the standard regeneration temperature). The effect of insufficient temperature is compensated by extending the regeneration time to 2.5h and reducing the flow rate to 2.0BV / h. No additional heat is added during the regeneration process; the water temperature is maintained only by the insulation layer (temperature fluctuation ≤2℃). After regeneration, deionized water is preheated with waste heat at 35℃ and rinsed for 1.5h to further reduce energy consumption. S5 Regenerated Waste Liquid Treatment: The regenerated waste liquid is kept at 70°C using waste heat and separated into layers after standing for 2.5 hours. The separated aqueous phase directly enters the waste heat preheating system and is preheated to 35°C together with the solution to be treated, thus achieving a dual cycle of heat and water resources. Results: The oily impurity content of the nickel sulfate solution after treatment was 0.48 mg / L, the resin regeneration rate was 98.2%, and the energy consumption in the regeneration stage was reduced by 42% compared with Example 1. It is suitable for industrial plants with a stable source of waste heat, and the overall cost is further reduced.

Claims

1. A method for deep degreasing with nickel sulfate solution resin, comprising the following steps: S1 degreasing resin pretreatment: Modified polystyrene-divinylbenzene macroporous adsorption resin was selected as the degreasing resin, and it was subjected to acid leaching and deionized water rinsing until pH=3.5~4.5 to obtain the pretreated degreasing resin. S2 nickel sulfate solution pretreatment: The nickel sulfate solution to be treated is filtered through a precision filter, and the temperature of the resulting filtrate is controlled at 30~40℃; S3 resin column deep degreasing: The resulting filtrate is passed into a fixed-bed resin column packed with pretreated degreasing resin at a flow rate of 1~3 BV / h, and adsorbed at 30~40℃. The content of oily impurities in the outlet solution is monitored to obtain the treated nickel sulfate solution. Hot water regeneration of S4 degreasing resin: The resin column under saturation was backwashed with deionized water at 80-90℃ as a regenerator, and the oily hot water generated during the regeneration process was collected as regeneration waste liquid. After regeneration, the resin column was rinsed with deionized water at 30-40℃ until the adsorption capacity was restored. S5 Regenerated Waste Liquid Treatment: The recycled waste liquid is separated into oil and water, and the aqueous phase is cooled to 30~40℃ before being returned to step S2 for recycling.

2. The method for deep degreasing with nickel sulfate solution resin as described in claim 1, characterized in that: In step S1, hydroxyl and carboxyl functional groups are grafted onto the surface of the modified polystyrene-divinylbenzene macroporous adsorption resin; the resin has a particle size of 0.3~0.8 mm and a specific surface area of ​​800~1200 m². 2 / g, with a pore volume of 0.8~1.2mL / g.

3. The method for deep degreasing with nickel sulfate solution resin as described in claim 1, characterized in that: In step S1, acid immersion refers to soaking in a 5% sulfuric acid solution for 2 hours.

4. The method for deep degreasing with nickel sulfate solution resin as described in claim 1, characterized in that: In step S2, the Ni in the nickel sulfate solution to be treated 2+ The concentration is 50~80g / L, pH=2.0~3.0, and the content of oily impurities is 5~20mg / L.

5. The method for deep degreasing with nickel sulfate solution resin as described in claim 1, characterized in that: The precision filter in step S2 has a filtration accuracy of 5 μm.

6. The method for deep degreasing with nickel sulfate solution resin as described in claim 1, characterized in that: In step S3, the resin column diameter-to-height ratio is 1:8 to 1:12; when the oily impurity content of the outlet solution is between 0.45 and 0.50 mg / L, the liquid feeding is stopped.

7. The method for deep degreasing with nickel sulfate solution resin as described in claim 1, characterized in that: The oily impurity content of the nickel sulfate solution after treatment in step S3 is ≤0.5mg / L.

8. The method for deep degreasing with nickel sulfate solution resin as described in claim 1, characterized in that: In step S4, the regeneration flow rate is 2~4 BV / h and the time is 1.5~2.5h; the rinsing flow rate is 1~2 BV / h and the time is 1~1.5h.

9. The method for deep degreasing with nickel sulfate solution resin as described in claim 1, characterized in that: The conditions for oil-water separation in step S5 are a temperature of 70~80℃ and standing for 2~3 hours to separate the layers.

10. The method for deep degreasing with nickel sulfate solution resin as described in claim 1, characterized in that: The modified polystyrene-divinylbenzene macroporous adsorption resin in step S1 is recycled ≥50 times.