A membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors.

Abstract

This invention relates to a membrane-based method for the resource recovery of nickel sulfate anolyte in the production of ternary lithium battery precursors, comprising the following steps: S1: Pretreatment of the anolyte. S2: The pretreated effluent enters a primary nanofiltration structure. S3: The permeate from the primary nanofiltration enters a secondary nanofiltration structure. S4: The permeate from the secondary nanofiltration enters a tertiary nanofiltration structure. S5: The concentrate from the primary and secondary nanofiltration processes is mixed and enters a water-washing nanofiltration structure. S6: The permeate from the water-washing nanofiltration enters a first-stage reverse osmosis structure. S7: The concentrate from the first-stage concentration is mixed with the permeate from the secondary nanofiltration process and enters the tertiary nanofiltration structure; the permeate and concentrate from the tertiary nanofiltration enter the concentrate reverse osmosis and secondary nanofiltration structures, respectively. S8: All the permeate from the first-stage reverse osmosis and the concentrate reverse osmosis enters the water-washing nanofiltration structure. This invention achieves the separation of nickel sulfate and sulfuric acid in the anolyte, achieving a nickel sulfate recovery rate of over 99%, without generating wastewater or adding reagents, and increasing the overall permeate flux.

Description

Technical Field

[0001] This invention relates to the field of electrolytic nickel sulfate production technology, specifically to a membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary precursors for lithium batteries. Background Technology

[0002] Nickel sulfate (NiSO4), an important chemical raw material, is widely used in electroplating, batteries, printing and dyeing, pharmaceuticals, construction, and other fields. Currently, the preparation processes of nickel sulfate include, but are not limited to, the following:

[0003] The process involves using high-purity nickel matte as raw material, finely grinding it, then leaching it with air under normal pressure, adding sulfuric acid, and continuously stirring. After leaching, the liquid and solid are separated, and the separated liquid is then vacuum evaporated and crystallized to produce high-purity nickel sulfate.

[0004] The process of producing nickel sulfate by using nickel-containing waste materials as raw materials and through operations such as acid dissolution, hydrolysis, extraction, and back-extraction.

[0005] The process involves using laterite nickel ore as raw material to produce crude nickel hydroxide, which is then dissolved into crude nickel sulfate solution and further purified to produce nickel sulfate products.

[0006] Another method involves using a nickel plate as the anode, electrolyzing it to precipitate nickel onto the cathode, yielding high-purity nickel. This high-purity nickel is then used to prepare nickel sulfate, which is subsequently used in the production of ternary precursors for lithium-ion batteries. In this electrolytic process, the nickel plate dissolves into the nickel sulfate anolyte, which is a nickel sulfate solution, while the cathode solution is a sulfuric acid solution. The anolyte can be recycled by adding electrolyte. This electrolytic method for producing nickel sulfate is short, introduces no impurities, produces high-quality products, and has a high nickel utilization rate. However, as electrolysis progresses, the sulfuric acid concentration gradually increases. When the sulfuric acid concentration reaches a certain limit, it affects the current efficiency, making it impossible to recycle the anolyte. Therefore, the resulting nickel sulfate anolyte is treated as waste.

[0007] Currently, the common method for treating waste anolyte is to add alkali to recover nickel ions as precipitation. This method is costly, the addition of alkali introduces new impurity ions, the recovery efficiency is low, it generates a large amount of nickel-containing wastewater that is difficult to treat, and it also wastes the sulfuric acid resources in the anolyte.

[0008] Therefore, there is a need to provide a resource recovery method for nickel sulfate anolyte generated in the production of ternary precursors for lithium batteries, which separates sulfuric acid and nickel sulfate in the anolyte to reduce resource waste. Summary of the Invention

[0009] (a) Technical problems to be solved

[0010] In view of the above-mentioned technical problems, in order to solve the problem that the increased sulfuric acid concentration in the anolyte during the electrolytic preparation of nickel sulfate in the existing technology affects the circulation of the anolyte and makes the nickel sulfate anolyte a difficult-to-treat waste, the present invention provides a membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary precursors for lithium batteries.

[0011] (II) Technical Solution

[0012] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0013] A membrane-based method for the resource recovery of nickel sulfate anolyte in the production of ternary lithium battery precursors includes the following steps:

[0014] S1: Pretreatment of nickel sulfate anolyte containing sulfuric acid;

[0015] S2: The pretreated effluent obtained in step S1 enters the primary nanofiltration structure for primary nanofiltration treatment;

[0016] S3: The permeate from the primary nanofiltration treatment enters the secondary nanofiltration structure for secondary nanofiltration treatment;

[0017] S4: The permeate from the secondary nanofiltration treatment enters the tertiary nanofiltration structure for further tertiary nanofiltration treatment;

[0018] S5: The concentrate from the primary nanofiltration treatment is mixed with the concentrate from the secondary nanofiltration treatment and then enters the water-washing nanofiltration structure for water-washing nanofiltration treatment;

[0019] S6: The permeate from the water washing nanofiltration treatment enters a reverse osmosis section for a concentration process;

[0020] S7: The concentrated water from the first stage of concentration treatment is mixed with the permeate from the second stage nanofiltration treatment in step S3 and then enters the third stage nanofiltration structure for nanofiltration treatment. The permeate from the third stage nanofiltration treatment enters the concentrated water reverse osmosis structure for concentrated water reverse osmosis treatment. The concentrated water from the third stage nanofiltration treatment enters the second stage nanofiltration structure.

[0021] S8: The permeate from the first stage of reverse osmosis and the concentrated water reverse osmosis treatment is used as wash water and all enters the water washing nanofiltration structure.

[0022] In the membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors as described above, preferably, in step S1, the nickel sulfate anolyte containing sulfuric acid enters the microfiltration structure through a water flow adjustment component, and the microfiltration structure intercepts suspended solids in the nickel sulfate anolyte containing sulfuric acid.

[0023] In the membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors as described above, preferably, in step S2, the primary nanofiltration structure has an interception rate of 50-70% for nickel ions and an interception rate of 4-5% for sulfuric acid. The inlet water pressure of the primary nanofiltration structure is 40-50 bar, the average permeate membrane flux of the primary nanofiltration structure is 16-18 LMH, and the recovery rate of the primary nanofiltration treatment is 60-75%.

[0024] In the membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors as described above, preferably, in step S3, the secondary nanofiltration structure has an interception rate of 95-99% for nickel ions and an interception rate of 8-10% for sulfuric acid. The inlet pressure of the secondary nanofiltration structure is 50-60 bar, the average permeate membrane flux of the secondary nanofiltration structure is 14-15 LMH, and the recovery rate of the secondary nanofiltration treatment is 65-70%.

[0025] In the membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors as described above, preferably, in steps S4 and S7, the three-stage nanofiltration structure has an interception rate of 95-99% for nickel ions and an interception rate of 15-20% for sulfuric acid. The inlet water pressure of the three-stage nanofiltration structure is 10-35 bar, the average permeate membrane flux of the three-stage nanofiltration structure is 16-18 LMH, and the recovery rate of the three-stage nanofiltration treatment is 80-85%.

[0026] In the membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors as described above, preferably, in steps S5 and S8, the water-washing nanofiltration structure has an interception rate of 95-99% for nickel ions and an interception rate of 15-20% for sulfuric acid. The inlet water pressure of the water-washing nanofiltration structure is 30-40 bar, the average permeate membrane flux of the water-washing nanofiltration structure is 16-22 LMH, and during the water-washing nanofiltration treatment, the ratio of the total amount of concentrate from the primary nanofiltration treatment and the secondary nanofiltration treatment to the amount of wash water is 1:3-1:5. The number of water-washing nanofiltration treatments is 2-3 times, and the recovery rate of the water-washing nanofiltration treatment is 75-80%.

[0027] In the membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors as described above, preferably, in step S6, the first-stage reverse osmosis structure has a nickel ion removal rate of 99% and a sulfuric acid removal rate of 85-90%, the inlet water pressure of the first-stage reverse osmosis structure is 30-50 bar, the average permeate membrane flux of the first-stage reverse osmosis structure is 16-18 LMH, and the recovery rate of the first-stage concentration treatment is 65-85%.

[0028] In the membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors as described above, preferably, in step S7, the concentrate reverse osmosis structure has a nickel ion removal rate of 99% and a sulfuric acid removal rate of 80-85%, the feed water pressure of the concentrate reverse osmosis structure is 50-70 bar, the average permeate membrane flux of the concentrate reverse osmosis structure is 15-16 LMH, and the recovery rate of the concentrate reverse osmosis treatment is 50-72%.

[0029] The membrane-based resource recovery method for nickel sulfate anolyte in the production of lithium battery ternary precursors, as described above, preferably includes step S1 in which the nickel ion content in the sulfuric acid-containing nickel sulfate anolyte is 40-60 g / L and the sulfuric acid mass concentration is 5-6%.

[0030] (III) Beneficial Effects

[0031] This invention achieves the separation of nickel sulfate and sulfuric acid in anolyte through the separation effects of a primary nanofiltration structure, a secondary nanofiltration structure, a tertiary nanofiltration structure, and a water-washing nanofiltration structure, as well as the concentration effect of a two-stage reverse osmosis structure. The concentrated water from the reverse osmosis structure is used as the sulfuric acid product, and the concentrated water from the water-washing nanofiltration structure is used as the nickel sulfate product. It can directly produce recyclable nickel sulfate and sulfuric acid. Furthermore, through the combined use of various nanofiltration structures, the recovery rate of nickel sulfate reaches over 99%, and the overall water flux is significantly improved while reducing the system pressure.

[0032] In the recovery method of this invention, the permeate from the first stage of reverse osmosis treatment and the permeate from the concentrated reverse osmosis treatment are all fed into the water-washing nanofiltration structure as wash water to dilute the concentrated water from each stage of the nanofiltration structure. This ensures that the entire process generates no wastewater and requires no wastewater treatment. Furthermore, the nickel sulfate anolyte treatment method of this invention requires no reagent addition, poses no risk of secondary pollution, has a high metal recovery rate, and low operating costs. It can not only be practically applied to the treatment of nickel sulfate anolyte but can also be extended to the resource recovery treatment of other types of waste acids containing high-valence metals. Attached Figure Description

[0033] Figure 1 This is a process flow diagram of the membrane-based resource recovery method for nickel sulfate anolyte in the production of lithium battery ternary precursors according to the present invention. Detailed Implementation

[0034] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] like Figure 1 As shown, this invention provides a membrane-based method for the resource recovery of nickel sulfate anolyte in the production of ternary lithium battery precursors, comprising the following steps:

[0036] S1: Pretreatment of nickel sulfate anolyte containing sulfuric acid.

[0037] S2: The pretreated effluent obtained in step S1 enters the primary nanofiltration structure for primary nanofiltration treatment.

[0038] S3: The permeate from the primary nanofiltration treatment enters the secondary nanofiltration structure for secondary nanofiltration treatment.

[0039] S4: The permeate from the secondary nanofiltration treatment enters the tertiary nanofiltration structure for further tertiary nanofiltration treatment.

[0040] S5: The concentrate from the primary nanofiltration treatment is mixed with the concentrate from the secondary nanofiltration treatment and then enters the water-washing nanofiltration structure for water-washing nanofiltration treatment.

[0041] S6: The permeate from the water washing nanofiltration process enters a reverse osmosis section for a concentration process.

[0042] S7: The concentrate from the first stage of concentration treatment is mixed with the permeate from the second stage of nanofiltration treatment in step S3 and then enters the third stage nanofiltration structure for nanofiltration treatment. The permeate from the third stage nanofiltration treatment enters the concentrate reverse osmosis structure for concentrate reverse osmosis treatment, and the concentrate from the third stage nanofiltration treatment enters the second stage nanofiltration structure.

[0043] S8: The permeate from the first stage of reverse osmosis and the concentrated water reverse osmosis treatment is used as wash water and all enters the water washing nanofiltration structure.

[0044] In the above steps, the concentrate from the reverse osmosis structure is a high-concentration sulfuric acid product, while the concentrate from the water washing nanofiltration structure is a nickel sulfate component.

[0045] In step S1 above, the nickel sulfate anolyte containing sulfuric acid can enter the microfiltration structure through the water flow regulating component. The function of the water flow regulating component is to regulate the amount of anolyte entering the entire system, that is, to regulate the total amount of anolyte processed by the entire system. The microfiltration structure is used to intercept suspended solids in the nickel sulfate anolyte containing sulfuric acid, so as to avoid damage to the nanofiltration structure. Preferably, the microfiltration structure can be a precision filter element. After passing through the microfiltration structure and meeting the standards, the anolyte enters the primary nanofiltration structure.

[0046] In this invention, the entire nanofiltration structure, including the primary nanofiltration structure, the secondary nanofiltration structure, the tertiary nanofiltration structure, and the water-washing nanofiltration structure, serves the following two purposes: 1. to concentrate nickel sulfate and sulfuric acid respectively; 2. to separate sulfuric acid and nickel sulfate in the anolyte.

[0047] Specifically, in step S2, the primary nanofiltration structure uses a special nanofiltration membrane with a nickel ion rejection rate of 50-70% and a sulfuric acid rejection rate of 4-5%. In step S2, by adjusting the anolyte inlet flow rate, inlet water pressure, and the average permeate membrane flux of the primary nanofiltration structure, the recovery rate of the primary nanofiltration treatment is achieved to 60-75%. If the recovery rate of the primary nanofiltration structure is higher than the above range, the concentration of nickel sulfate in the resulting concentrate will be too high, making it difficult to enter the next nanofiltration structure. Preferably, the inlet water pressure of the primary nanofiltration structure is 40-50 bar, which can be controlled within this range using a pump. The average permeate membrane flux of the primary nanofiltration structure is preferably 16-18 LMH.

[0048] In the primary nanofiltration structure, nickel sulfate and sulfuric acid are initially separated. The permeate from the primary nanofiltration process contains sulfuric acid and medium-concentration nickel sulfate, while the concentrate from the primary nanofiltration process contains sulfuric acid and high-concentration nickel sulfate.

[0049] In step S3, the nanofiltration membrane used in the secondary nanofiltration structure has an interception rate of 95-99% for nickel ions and an interception rate of 8-10% for sulfuric acid. In step S3, the recovery rate of the secondary nanofiltration treatment is controlled to 65-70% by adjusting the anolyte inlet flow rate, inlet water pressure, and the average permeate membrane flux of the secondary nanofiltration structure. Specifically, the inlet water pressure of the secondary nanofiltration structure is 50-60 bar, which can be controlled within this range by a pump. The preferred average permeate membrane flux of the secondary nanofiltration structure is 14-15 LMH.

[0050] In a two-stage nanofiltration structure, nickel sulfate and sulfuric acid are further separated in the permeate from the first-stage nanofiltration process. The permeate from the second-stage nanofiltration process contains sulfuric acid and low-concentration nickel sulfate, while the concentrate from the second-stage nanofiltration process contains sulfuric acid and high-concentration nickel sulfate.

[0051] In steps S4 and S7, the three-stage nanofiltration structure achieves a nickel ion rejection rate of 95-99% and a sulfuric acid rejection rate of 15-20%. The recovery rate of the three-stage nanofiltration treatment is controlled to 80-85% by adjusting the anolyte inlet flow rate, inlet water pressure, and the average permeate membrane flux of the three-stage nanofiltration structure. Specifically, the inlet water pressure of the three-stage nanofiltration structure is 10-35 bar, and the inlet water pressure of the two-stage nanofiltration structure can be controlled within this range using a pump. The preferred average permeate membrane flux of the three-stage nanofiltration structure is 16-18 LMH.

[0052] In step S4, within the three-stage nanofiltration structure, nickel sulfate and sulfuric acid continue to separate in the permeate from the second-stage nanofiltration treatment. In step S7, within the three-stage nanofiltration structure, sulfuric acid and nickel sulfate continue to separate in the concentrate from the first-stage concentration treatment. The permeate from the three-stage nanofiltration treatment contains sulfuric acid and very low concentrations of nickel sulfate, while the concentrate from the three-stage nanofiltration treatment contains sulfuric acid and medium concentrations of nickel sulfate.

[0053] In steps S5 and S8, the interception rate of nickel ions by the water-washing nanofiltration structure is 95-99%, and the interception rate of sulfuric acid is 15-20%. The inlet water pressure of the water-washing nanofiltration structure is 30-40 bar, and the average permeate membrane flux is 16-22 LMH. During the water-washing nanofiltration treatment, the ratio of the total amount of concentrate from the primary nanofiltration stage and the concentrate from the secondary nanofiltration stage to the wash water volume is 1:3-1:5, i.e., the volume ratio of inlet water to wash water is 1:3-1:5, and the recovery rate of the water-washing nanofiltration treatment is 75-80%. Preferably, the water-washing nanofiltration treatment is performed 2-3 times. The concentrate from the water-washing nanofiltration treatment contains a small amount of sulfuric acid and a high concentration of nickel sulfate. The sulfuric acid concentration can be adjusted according to the ratio of wash water volume to inlet water volume during the water washing process to further reduce the sulfuric acid content and meet the requirements for anolyte reuse. The permeate from the water-washing nanofiltration treatment contains sulfuric acid and a very low concentration of nickel sulfate.

[0054] The permeate from the water-washing nanofiltration treatment enters a first-stage reverse osmosis structure, where the sulfuric acid is concentrated. In step S6, the first-stage reverse osmosis structure achieves a nickel ion removal rate of 99% and a sulfuric acid removal rate of 85-90%. The recovery rate of the first-stage concentration treatment is controlled at 65-85% by adjusting the influent flow rate, influent pressure, and the average permeate membrane flux of the first-stage reverse osmosis structure. The influent pressure of the first-stage reverse osmosis structure is 30-50 bar, which can be controlled within this range using a pump. The preferred average permeate membrane flux of the first-stage reverse osmosis structure is 16-18 LMH. The permeate from the first-stage concentration treatment can be used as wash water to enter the water-washing nanofiltration structure.

[0055] In step S7, the concentrate reverse osmosis structure achieves a nickel ion removal rate of 99% and a sulfuric acid removal rate of 80-85%. The recovery rate of the concentrate reverse osmosis treatment is controlled at 50-72% by adjusting the influent flow rate, influent pressure, and the average permeate membrane flux of the concentrate reverse osmosis structure. Specifically, the influent pressure of the concentrate reverse osmosis structure is 50-70 bar, which can be adjusted within this range using pumps or similar mechanisms. The preferred average permeate membrane flux of the concentrate reverse osmosis structure is 15-16 LMH. By adjusting the anolyte flow rate using a flow regulating component, all the permeate from the concentrate reverse osmosis treatment can be used as wash water to enter the water-washing nanofiltration structure to dilute the sulfuric acid in the concentrate from each nanofiltration structure. This eliminates the need to add deionized water or tap water as wash water to the entire system, and avoids generating any wastewater. No wastewater treatment is required, enabling material recycling. The concentrate from the concentrate reverse osmosis treatment is concentrated sulfuric acid.

[0056] In this invention, "recovery rate" refers to the ratio of produced water to influent in each structure.

[0057] This invention achieves the separation of nickel sulfate and sulfuric acid in the anolyte through the separation function of various nanofiltration structures and the concentration function of two-stage reverse osmosis structures. It can directly produce recyclable nickel sulfate and sulfuric acid. Furthermore, through the combined use of various nanofiltration structures, the recovery rate of nickel sulfate reaches over 99%, and the overall water production flux is significantly improved while reducing the system pressure.

[0058] The method for treating nickel sulfate anolyte of the present invention does not require the addition of reagents, has no risk of secondary pollution, has a high metal recovery rate, and low operating costs. It can not only be practically applied to the treatment of nickel sulfate anolyte, but can also be extended to the resource recovery treatment of other types of waste acid containing high-value metals.

[0059] The nickel sulfate recovered by this invention can be added to the electrolyte for recycling, or it can be used as a high-purity nickel sulfate product.

[0060] This invention can treat anolytes with a nickel ion content of 40-60 g / L and a sulfuric acid mass concentration of 5-6%, thereby achieving better separation of sulfuric acid and nickel sulfate and high recovery of nickel sulfate.

[0061] To further clarify the present invention and its technological advancements, the following description is provided in conjunction with specific embodiments and technical effects.

[0062] Example 1

[0063] This embodiment provides a membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors. The nickel sulfate anolyte being treated has a nickel ion concentration of 50 g / L and a sulfuric acid mass fraction of 5%. The recovery method includes the following steps:

[0064] S1: The anolyte is collected in the water flow regulating tank and then enters the microfiltration structure to remove suspended solids.

[0065] S2: The effluent from the microfiltration structure enters the primary nanofiltration structure. The inlet pressure of the primary nanofiltration structure is 45 bar, and the average permeate membrane flux is 16 LMH. The primary nanofiltration treatment achieves a recovery rate of 75%. Testing revealed that the permeate from the primary nanofiltration treatment contained 4.6% sulfuric acid and 24.75 g / L nickel ions, while the concentrate from the primary nanofiltration treatment contained 5.4% sulfuric acid and 108.9 g / L nickel ions.

[0066] S3: The permeate from the primary nanofiltration stage enters the secondary nanofiltration stage. The inlet pressure of the secondary nanofiltration stage is 60 bar, and the average permeate membrane flux is 14 LMH. Secondary nanofiltration treatment is performed with a recovery rate of 70%. Testing revealed that the permeate from the secondary nanofiltration stage contains 4.1% sulfuric acid and 0.25 g / L nickel ions, while the concentrate from the secondary nanofiltration stage contains 5.8% sulfuric acid and 81.9 g / L nickel ions.

[0067] S4: The concentrate from the primary nanofiltration treatment is mixed with the concentrate from the secondary nanofiltration treatment and then enters the water-washing nanofiltration structure for washing. The water washing process involves two washes with a dilution factor of three times. The inlet pressure of the water-washing nanofiltration structure is 35 bar, the average permeate membrane flux is 20 LMH, and the recovery rate is 76%. The concentrate from the water-washing nanofiltration treatment contains 1.9% sulfuric acid and 90.7 g / L nickel ions by mass.

[0068] S5: The permeate from the water-wash nanofiltration treatment enters a first-stage reverse osmosis structure to concentrate the sulfuric acid. The feed pressure of the first-stage reverse osmosis structure is 30 bar, the average permeate membrane flux is 18 LMH, and the recovery rate is 76%. The permeate from the first-stage concentration treatment (containing 0.2% sulfuric acid and 0.01 g / L nickel ions) is used as the wash water in step S4 and enters the water-wash nanofiltration structure. The concentrate from the first-stage concentration treatment (containing 3.3% sulfuric acid and 4.39 g / L nickel ions) enters the third-stage nanofiltration structure.

[0069] S6: The concentrate from the first-stage concentration treatment and the permeate from the second-stage nanofiltration treatment are mixed and then enter the third-stage nanofiltration structure to recover nickel sulfate. The inlet pressure of the third-stage nanofiltration structure is 10 bar, the average permeate membrane flux is 18 LMH, and the recovery rate is 85%. The permeate from the third-stage nanofiltration treatment (containing 3.2% sulfuric acid and 0.15 g / L nickel ions) enters the concentrate reverse osmosis structure for concentration, and the concentrate from the third-stage nanofiltration treatment (containing 7% sulfuric acid and 19.12 g / L nickel ions) enters the second-stage nanofiltration structure.

[0070] S7: The feed water pressure of the concentrate reverse osmosis structure is 65 bar, the average permeate membrane flux is 14 LMH, and the recovery rate is 72%. The permeate from the concentrate reverse osmosis treatment (containing 0.6% sulfuric acid and 0.001 g / L nickel ions) is used as the wash water in step S4 and enters the water-washing nanofiltration structure. The concentrate from the concentrate reverse osmosis structure is concentrated sulfuric acid (containing 10% sulfuric acid and 0.53 g / L nickel ions).

[0071] Calculations show that the recovery rate of nickel sulfate in this embodiment is 99.3%.

[0072] Example 2

[0073] This embodiment provides a membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors. The nickel sulfate anolyte being treated has a nickel ion concentration of 60 g / L and a sulfuric acid mass fraction of 6%. The recovery method includes the following steps:

[0074] S1: The anolyte is collected in the water flow regulating tank and then enters the microfiltration structure to remove suspended solids.

[0075] S2: The effluent from the microfiltration structure enters the primary nanofiltration structure. The inlet pressure of the primary nanofiltration structure is 50 bar, and the average permeate membrane flux is 16 LMH. The primary nanofiltration process achieves a recovery rate of 70%. Testing revealed that the permeate from the primary nanofiltration process contained 5.7% sulfuric acid and 29.5 g / L nickel ions, while the concentrate contained 6.7% sulfuric acid and 115.9 g / L nickel ions.

[0076] S3: The permeate from the primary nanofiltration stage enters the secondary nanofiltration stage. The inlet pressure of the secondary nanofiltration stage is 60 bar, and the average permeate membrane flux is 15 LMH. Secondary nanofiltration treatment is performed with a recovery rate of 65%. Testing revealed that the permeate from the secondary nanofiltration stage contains 5.4% sulfuric acid and 1.18 g / L nickel ions, while the concentrate from the secondary nanofiltration stage contains 10% sulfuric acid and 89.9 g / L nickel ions.

[0077] S4: The concentrate from the primary nanofiltration treatment is mixed with the concentrate from the secondary nanofiltration treatment and then enters the water-washing nanofiltration structure for washing. The water washing process involves two washes with a dilution factor of three times. The inlet pressure of the water-washing nanofiltration structure is 40 bar, the average permeate membrane flux is 20 LMH, and the recovery rate is 76%. The concentrate from the water-washing nanofiltration treatment contains 3% sulfuric acid and 109.1 g / L nickel ions by mass.

[0078] S5: The permeate from the water-wash nanofiltration treatment enters a first-stage reverse osmosis structure to concentrate the sulfuric acid. The feed pressure of the first-stage reverse osmosis structure is 40 bar, the average permeate membrane flux is 17 LMH, and the recovery rate is 76%. The permeate from the first-stage concentration treatment (containing 0.7% sulfuric acid and 0.01 g / L nickel ions) is used as the wash water in step S4 and enters the water-wash nanofiltration structure. The concentrate from the first-stage concentration treatment (containing 5.9% sulfuric acid and 5.97 g / L nickel ions) enters the third-stage nanofiltration structure.

[0079] S6: The concentrate from the first-stage concentration treatment and the permeate from the second-stage nanofiltration treatment are mixed and then enter the third-stage nanofiltration structure to recover nickel sulfate. The inlet pressure of the third-stage nanofiltration structure is 15 bar, the average permeate membrane flux is 16 LMH, and the recovery rate is 85%. The permeate from the third-stage nanofiltration treatment (containing 4.1% sulfuric acid and 0.19 g / L nickel ions) enters the concentrate reverse osmosis structure for concentration, and the concentrate from the third-stage nanofiltration treatment (containing 7% sulfuric acid and 25.8 g / L nickel ions) enters the second-stage nanofiltration structure.

[0080] S7: The feed water pressure of the concentrate reverse osmosis structure is 60 bar, the average permeate membrane flux is 15 LMH, and the recovery rate is 60%. The permeate from the concentrate reverse osmosis treatment (containing 0.6% sulfuric acid and 0.002 g / L nickel ions) is used as the wash water in step S4 and enters the water-washing nanofiltration structure. The concentrate from the concentrate reverse osmosis structure is concentrated sulfuric acid (containing 14% sulfuric acid and 0.69 g / L nickel ions).

[0081] Calculations show that the recovery rate of nickel sulfate in this embodiment is 99.5%.

[0082] Example 3

[0083] This embodiment provides a membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors. The nickel sulfate anolyte being treated has a nickel ion concentration of 60 g / L and a sulfuric acid mass fraction of 5.5%. The recovery method includes the following steps:

[0084] S1: The anolyte is collected in the water flow regulating tank and then enters the microfiltration structure to remove suspended solids.

[0085] S2: The effluent from the microfiltration structure enters the primary nanofiltration structure. The inlet pressure of the primary nanofiltration structure is 45 bar, and the average permeate membrane flux is 16 LMH. The primary nanofiltration process achieves a recovery rate of 60%. Testing revealed that the permeate from the primary nanofiltration process contained 7.6% sulfuric acid and 30 g / L nickel ions, while the concentrate contained 8.4% sulfuric acid and 90 g / L nickel ions.

[0086] S3: The permeate from the primary nanofiltration stage enters the secondary nanofiltration stage. The inlet pressure of the secondary nanofiltration stage is 60 bar, and the average permeate membrane flux is 14.5 LMH. Secondary nanofiltration treatment is performed with a recovery rate of 70%. Testing revealed that the permeate from the secondary nanofiltration stage contains 7.5% sulfuric acid and 1.4 g / L nickel ions, while the concentrate from the secondary nanofiltration stage contains 8.7% sulfuric acid and 90 g / L nickel ions.

[0087] S4: The concentrate from the primary nanofiltration treatment is mixed with the concentrate from the secondary nanofiltration treatment and then enters the water-washing nanofiltration structure for washing. The water washing process involves two washes with a dilution factor of four times. The inlet pressure of the water-washing nanofiltration structure is 40 bar, the average permeate membrane flux is 16 LMH, and the recovery rate is 80%. The concentrate from the water-washing nanofiltration treatment contains 2% sulfuric acid and 90.7 g / L nickel ions by mass.

[0088] S5: The permeate from the water-wash nanofiltration treatment enters a first-stage reverse osmosis structure to concentrate the sulfuric acid. The feed pressure of the first-stage reverse osmosis structure is 50 bar, the average permeate membrane flux is 16 LMH, and the recovery rate is 85%. The permeate from the first-stage concentration treatment (containing 0.2% sulfuric acid and 0.01 g / L nickel ions) is used as the wash water in step S4 and enters the water-wash nanofiltration structure. The concentrate from the first-stage concentration treatment (containing 5.8% sulfuric acid and 6.56 g / L nickel ions) enters the third-stage nanofiltration structure.

[0089] S6: The concentrate from the first-stage concentration treatment and the permeate from the second-stage nanofiltration treatment are mixed and then enter the third-stage nanofiltration structure to recover nickel sulfate. The inlet pressure of the third-stage nanofiltration structure is 35 bar, the average permeate membrane flux is 17 LMH, and the recovery rate is 85%. The permeate from the third-stage nanofiltration treatment (containing 6% sulfuric acid and 0.25 g / L nickel ions) enters the concentrate reverse osmosis structure for concentration, and the concentrate from the third-stage nanofiltration treatment (containing 8% sulfuric acid and 28.12 g / L nickel ions) enters the second-stage nanofiltration structure.

[0090] S7: The feed water pressure of the concentrate reverse osmosis structure is 70 bar, the average permeate membrane flux is 15 LMH, and the recovery rate is 68%. The permeate from the concentrate reverse osmosis treatment (containing 1.2% sulfuric acid by mass and 0.002 g / L nickel ions) is used as the wash water in step S4 and enters the water-washing nanofiltration structure. The concentrate from the concentrate reverse osmosis structure is concentrated sulfuric acid (containing 14% sulfuric acid by mass and 0.68 g / L nickel ions).

[0091] Calculations show that the recovery rate of nickel sulfate in this embodiment is 99%.

[0092] Example 4

[0093] This embodiment provides a membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors. The nickel sulfate anolyte being treated has a nickel ion concentration of 55 g / L and a sulfuric acid mass fraction of 6%. The recovery method includes the following steps:

[0094] S1: The anolyte is collected in the water flow regulating tank and then enters the microfiltration structure to remove suspended solids.

[0095] S2: The effluent from the microfiltration structure enters the primary nanofiltration structure. The inlet pressure of the primary nanofiltration structure is 45 bar, and the average permeate membrane flux is 17 LMH. The primary nanofiltration process achieves a recovery rate of 70%. Testing revealed that the permeate from the primary nanofiltration process contained 5.8% sulfuric acid and 27.5 g / L nickel ions, while the concentrate contained 6.8% sulfuric acid and 118.9 g / L nickel ions.

[0096] S3: The permeate from the primary nanofiltration stage enters the secondary nanofiltration stage. The inlet pressure of the secondary nanofiltration stage is 50 bar, and the average permeate membrane flux is 15 LMH. Secondary nanofiltration treatment is performed with a recovery rate of 70%. Testing revealed that the permeate from the secondary nanofiltration stage contains 5.5% sulfuric acid and 1.3 g / L nickel ions, while the concentrate from the secondary nanofiltration stage contains 6.6% sulfuric acid and 91.9 g / L nickel ions.

[0097] S4: The concentrate from the primary nanofiltration treatment is mixed with the concentrate from the secondary nanofiltration treatment and then enters the water-washing nanofiltration structure for washing. The water washing process involves two washes with a dilution factor of three times. The inlet pressure of the water-washing nanofiltration structure is 30 bar, the average permeate membrane flux is 22 LMH, and the recovery rate is 75%. The concentrate from the water-washing nanofiltration treatment contains 2.3% sulfuric acid and 95.7 g / L nickel ions by mass.

[0098] S5: The permeate from the water-wash nanofiltration treatment enters a first-stage reverse osmosis structure to concentrate the sulfuric acid. The feed pressure of the first-stage reverse osmosis structure is 40 bar, the average permeate membrane flux is 16 LMH, and the recovery rate is 76%. The permeate from the first-stage concentration treatment (containing 0.2% sulfuric acid and 0.01 g / L nickel ions) is used as the wash water in step S4 and enters the water-wash nanofiltration structure. The concentrate from the first-stage concentration treatment (containing 4.4% sulfuric acid and 5.4 g / L nickel ions) enters the third-stage nanofiltration structure.

[0099] S6: The concentrate from the first-stage concentration treatment and the permeate from the second-stage nanofiltration treatment are mixed and then enter the third-stage nanofiltration structure to recover nickel sulfate. The inlet pressure of the third-stage nanofiltration structure is 20 bar, the average permeate membrane flux is 16 LMH, and the recovery rate is 85%. The permeate from the third-stage nanofiltration treatment (containing 4.7% sulfuric acid and 0.18 g / L nickel ions) enters the concentrate reverse osmosis structure for concentration, and the concentrate from the third-stage nanofiltration treatment (containing 6% sulfuric acid and 23.12 g / L nickel ions) enters the second-stage nanofiltration structure.

[0100] S7: The feed water pressure of the concentrate reverse osmosis structure is 65 bar, the average permeate membrane flux is 15 LMH, and the recovery rate is 60%. The permeate from the concentrate reverse osmosis treatment (containing 0.5% sulfuric acid and 0.002 g / L nickel ions) is used as the wash water in step S4 and enters the water-washing nanofiltration structure. The concentrate from the concentrate reverse osmosis structure is concentrated sulfuric acid (containing 10% sulfuric acid and 0.49 g / L nickel ions).

[0101] Calculations show that the recovery rate of nickel sulfate in this embodiment is 99.5%.

[0102] Comparative Example 1

[0103] This comparative example provides a membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors. The difference between this method and Example 1 is that a three-stage nanofiltration structure is not included.

[0104] Calculations show that the recovery rate of nickel sulfate in this embodiment is 95.3%.

[0105] In Examples 1-4, the recovery rate of nickel sulfate reached over 99%, although Comparative Example 1 achieved a recovery rate of over 90%. Hundreds of thousands of tons of waste nickel sulfate anolyte are generated annually, containing a large amount of recyclable nickel sulfate. Given the large volume of anolyte requiring treatment, every 1% increase in the nickel sulfate recovery rate significantly increases the amount of nickel sulfate recovered. Therefore, this invention can substantially increase the amount of nickel sulfate recovered, achieving resource-based recycling of anolyte.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A membrane-based method for the resource recovery of nickel sulfate anolyte in the production of ternary lithium battery precursors, characterized in that, Includes the following steps: S1: Pretreatment of nickel sulfate anolyte containing sulfuric acid; S2: The pretreated effluent obtained in step S1 enters a primary nanofiltration structure for primary nanofiltration treatment; the primary nanofiltration structure has a nickel ion rejection rate of 50-70% and a sulfuric acid rejection rate of 4-5%; the inlet pressure of the primary nanofiltration structure is 40-50 bar; the average permeate membrane flux of the primary nanofiltration structure is 16-18 LMH; and the recovery rate of the primary nanofiltration treatment is 60-75%. S3: The permeate from the primary nanofiltration treatment enters the secondary nanofiltration structure for further treatment; the secondary nanofiltration structure has a nickel ion rejection rate of 95-99% and a sulfuric acid rejection rate of 8-10%, the inlet pressure of the secondary nanofiltration structure is 50-60 bar, the average permeate membrane flux of the secondary nanofiltration structure is 14-15 LMH, and the recovery rate of the secondary nanofiltration treatment is 65-70%. S4: The permeate from the secondary nanofiltration treatment enters the tertiary nanofiltration structure for further tertiary nanofiltration treatment; S5: The concentrate from the primary nanofiltration treatment is mixed with the concentrate from the secondary nanofiltration treatment and then enters the water-washing nanofiltration structure for water-washing nanofiltration treatment; S6: The permeate from the water washing nanofiltration treatment enters a reverse osmosis section for a concentration process; S7: The concentrated water from the first stage of concentration treatment is mixed with the permeate from the second stage nanofiltration treatment in step S3 and then enters the third stage nanofiltration structure for nanofiltration treatment. The permeate from the third stage nanofiltration treatment enters the concentrated water reverse osmosis structure for concentrated water reverse osmosis treatment. The concentrated water from the third stage nanofiltration treatment enters the second stage nanofiltration structure. S8: The permeate from the first stage of reverse osmosis and the concentrated water reverse osmosis treatment is used as wash water and all enters the water washing nanofiltration structure; In steps S4 and S7, the three-stage nanofiltration structure has a nickel ion rejection rate of 95-99% and a sulfuric acid rejection rate of 15-20%. The influent pressure of the three-stage nanofiltration structure is 10-35 bar, the average permeate membrane flux of the three-stage nanofiltration structure is 16-18 LMH, and the recovery rate of the three-stage nanofiltration treatment is 80-85%. In steps S5 and S8, the water-washed nanofiltration structure has an interception rate of 95-99% for nickel ions and an interception rate of 15-20% for sulfuric acid. The inlet water pressure of the water-washed nanofiltration structure is 30-40 bar, and the average permeate membrane flux of the water-washed nanofiltration structure is 16-22 LMH. During the water-washed nanofiltration treatment, the ratio of the total amount of concentrate from the primary nanofiltration treatment and the secondary nanofiltration treatment to the amount of wash water is 1:3-1:

5. The number of water-washed nanofiltration treatments is 2-3 times, and the recovery rate of the water-washed nanofiltration treatment is 75-80%. The concentrated water from the reverse osmosis structure is used as a sulfuric acid product, while the concentrated water from the water washing nanofiltration structure is used as a nickel sulfate product.

2. The membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors according to claim 1, characterized in that, In step S1, the nickel sulfate anolyte containing sulfuric acid enters the microfiltration structure through the water flow adjustment component, and the microfiltration structure intercepts the suspended matter in the nickel sulfate anolyte containing sulfuric acid.

3. The membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors according to claim 1, characterized in that, In step S6, the first-stage reverse osmosis structure has a nickel ion removal rate of 99% and a sulfuric acid removal rate of 85-90%. The feed water pressure of the first-stage reverse osmosis structure is 30-50 bar, the average permeate membrane flux of the first-stage reverse osmosis structure is 16-18 LMH, and the recovery rate of the first-stage concentration treatment is 65-85%.

4. The membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors according to claim 1, characterized in that, In step S7, the concentrate reverse osmosis structure removes 99% of nickel ions and 80-85% of sulfuric acid. The feed water pressure of the concentrate reverse osmosis structure is 50-70 bar, the average permeate membrane flux of the concentrate reverse osmosis structure is 15-16 LMH, and the recovery rate of concentrate reverse osmosis treatment is 50-72%.

5. The membrane-based resource recovery method for nickel sulfate anolyte in the production of ternary lithium battery precursors according to claim 1, characterized in that, In step S1, the nickel ion content in the nickel sulfate anolyte containing sulfuric acid is 40-60 g / L, and the mass concentration of sulfuric acid is 5-6%.

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