Resource recycling treatment method for washing water in process of preparing iron phosphate from nickel-iron alloy

Abstract

A resource recycling treatment method for washing water in the process of preparing iron phosphate from a nickel-iron alloy, relating to the technical field of battery resource recovery. The method comprises carrying out precision membrane filtration, electrocoagulation reaction, disc filtration, bag filtration, acidic ultrafiltration, cation exchange, polishing filtration, primary acidic reverse osmosis treatment, etc., on iron phosphate washing water to be treated. By means of the aforementioned treatment, pure water in the iron phosphate washing water can be recycled under acidic conditions during the entire process without adjusting the pH value, thereby solving the problems of discharge and disposal of washing wastewater in iron phosphate. Furthermore, resource recycling cyclic comprehensive utilization can be formed. The entire treatment process does not introduce new ions interfering with the entire production system and is green, environmentally-friendly, and low in cost.

Description

A resource treatment method for washing water in the process of preparing ferrophosphate from nickel-iron alloy Technical Field

[0001] The present disclosure relates to the technical field of battery resource recovery, and in particular to a method for resource recovery of wash water in a process of preparing ferrophosphate from a nickel-iron alloy. Background Art

[0002] Lithium iron phosphate (LiFePO4) batteries are a new type of lithium battery. Iron phosphate is one of the main raw materials for preparing lithium iron phosphate, the positive electrode material for lithium iron phosphate batteries. The production process of iron phosphate often uses large amounts of water for washing and desalination, which produces a large amount of salt-containing washing wastewater (referred to as "wash water" or "iron phosphate wash water").

[0003] The cations in the wash water are mainly nickel salts, which also contain Ni 2+ 、Fe 2+ 、Mn 2+ Plasma, the anions are mainly sulfate, phosphate, etc., and the washing water contains a large number of suspended particles in the micron level.

[0004] If the pure water in the wash water is recovered by adding alkali precipitation first and then filtering it through a membrane, it is easy to cause membrane blockage and make the process difficult to implement. If the pure water in the wash water is not recovered and directly discharged, the water resources cannot be recycled, resulting in resource waste and possible environmental pollution.

[0005] In view of this, the present disclosure is proposed.

[0006] Summary of the Invention

[0007] The purpose of the present disclosure is to provide a resource-recycling method for washing water in the process of preparing ferrophosphate from nickel-iron alloy, so as to improve the above-mentioned technical problems.

[0008] The present disclosure can be implemented as follows:

[0009] The present disclosure provides a method for resource recovery of wash water in a process of preparing ferrophosphate from a nickel-iron alloy, comprising the following steps:

[0010] The iron phosphate wash water to be treated is subjected to precision membrane filtration to obtain the first intermediate wash water; the first intermediate wash water is subjected to electric flocculation reaction to obtain the second intermediate wash water; the second intermediate wash water is subjected to stacking filtration, bag filtration and acid ultrafiltration in sequence to obtain the third intermediate wash water; the third intermediate wash water is subjected to cation exchange to obtain the fourth intermediate wash water; the fourth intermediate wash water is subjected to security filtration and then subjected to primary acid reverse osmosis treatment.

[0011] In an optional embodiment, before performing the precision membrane filtration, the process further includes subjecting the iron phosphate wash water to be treated to a first transition treatment;

[0012] The pH value of the washing water after the first transition treatment is 1.5-3, the conductivity is ≤5000us / cm, SS (suspended matter content) is ≤1000mg / L, Ni 2+ ≤500mg / L, Fe 2+ ≤100mg / L, P≤100mg / L.

[0013] In an optional embodiment, the wash water after the first transition treatment is pressurized and then subjected to precision membrane filtration.

[0014] In an optional embodiment, the filtration accuracy of the precision membrane filter used in the precision membrane filtration process is 0.1 μm-0.5 μm.

[0015] In an optional embodiment, the waste obtained after the precision membrane filtration except the first intermediate wash water is subjected to solid-liquid separation to obtain a first liquid and a first solid;

[0016] The first liquid is used to return to the first transition process; the first solid is used to return to the wet leaching process.

[0017] In an optional embodiment, the flocculation product obtained after the electro-flocculation reaction, excluding the second intermediate wash water, is subjected to solid-liquid separation to obtain a second liquid and a second solid;

[0018] The second liquid is used to return to the first transition process; the second solid is used to return to the wet leaching process.

[0019] In an optional embodiment, the filter pore size of the laminated filter is 200 μm-400 μm, or the filter pore size of the bag filter is 50 μm-100 μm.

[0020] In an optional embodiment, the second intermediate wash water is subjected to a second transition treatment before the laminated filtration is performed.

[0021] In an optional embodiment, the intermediate wash water after the second transition treatment is pressurized and then subjected to laminate filtration.

[0022] In an optional embodiment, the filtration pore size of the acidic ultrafiltration membrane used in the acidic ultrafiltration process is 0.03 μm-0.06 μm.

[0023] In an optional embodiment, the cation exchange resin used for cation exchange has at least one of the following characteristics:

[0024] Feature 1: The cation exchange resin is a hydrogen-type cation exchange resin;

[0025] Feature 2: The resin model is CH-90;

[0026] Feature 3: The amount of resin used is 200L-400L.

[0027] In an optional embodiment, the fourth intermediate wash water is subjected to a third transition treatment before security filtration.

[0028] In an optional embodiment, the intermediate wash water after the third transition treatment is subjected to a pressurization treatment and then to a safety filtration to obtain the fifth intermediate wash water.

[0029] In an optional embodiment, the fifth intermediate wash water is subjected to a pressurization treatment and then to a primary acidic reverse osmosis treatment.

[0030] In an optional embodiment, the reverse osmosis membrane used in the primary acidic reverse osmosis process is of model RO-BW30-4040 or BW30-8040.

[0031] In an optional embodiment, the first-level acidic reverse osmosis treatment is followed by obtaining a sixth intermediate wash water and concentrated water, and the sixth intermediate wash water is subjected to a second-level acidic reverse osmosis treatment to obtain recycled water.

[0032] In an optional embodiment, the sixth intermediate wash water is first subjected to the fourth transition treatment and then subjected to the secondary acidic reverse osmosis treatment to be recycled.

[0033] In an optional embodiment, the reverse osmosis membrane used in the secondary acidic reverse osmosis process is of model RO-BW30LE-4040 or BW30LE-8040.

[0034] In an optional embodiment, the total content of sulfuric acid and phosphoric acid in the recycled water is ≤200 mg / L, and the recycled water does not contain metal ion impurities.

[0035] In an alternative embodiment, the recycled water is used to wash the ferric phosphate slurry.

[0036] In an optional embodiment, the concentrated water obtained after the first-level acidic reverse osmosis treatment is subjected to acidic concentrated water reverse osmosis treatment to obtain the seventh intermediate wash water and intermediate concentrated water. The seventh intermediate wash water is used to return to the security filtration treatment process; the intermediate concentrated water is used to analyze the resin used in the cation exchange process.

[0037] In an optional embodiment, the reverse osmosis membrane used in the reverse osmosis treatment of acidic concentrated water is RO-SW30HR-4040 or SW30HR-8040.

[0038] In an optional embodiment, the concentrated water is subjected to a fifth transition treatment before the acidic concentrated water reverse osmosis treatment.

[0039] In an optional embodiment, the intermediate wash water after the fifth transition treatment is subjected to a pressurization treatment and then to an acidic concentrated water reverse osmosis treatment to obtain the seventh intermediate wash water.

[0040] In an optional embodiment, the intermediate concentrated water is first filtered through a precision filter and then used to analyze the cation exchange resin.

[0041] In an optional embodiment, the intermediate concentrated water is subjected to a sixth transition treatment before being filtered through a precision filter.

[0042] In an optional embodiment, the concentrated water after the sixth transition treatment is pressurized and then filtered through a precision filter.

[0043] In an optional embodiment, part of the intermediate concentrated water obtained by filtration through a precision filter is subjected to desorption on a cation exchange resin, and the desorption liquid obtained by desorption is subjected to selective nickel removal by an ion exchange resin. The remaining intermediate concentrated water obtained by filtration through a precision filter is subjected to desorption on an ion exchange resin for selective nickel removal to obtain a nickel sulfate desorption solution and a nickel-removed liquid; the nickel sulfate desorption solution is evaporated, concentrated, and crystallized to obtain a nickel sulfate product; and the nickel-removed liquid is decontaminated and recycled to a wet leaching process.

[0044] In an optional embodiment, the resin used in the ion exchange resin selective nickel removal process has at least one of the following characteristics:

[0045] Feature 1: The resin model is CH-92;

[0046] Feature 2: The amount of resin used is 200L-400L.

[0047] In an optional embodiment, the analytical solution is subjected to a seventh transition treatment before selective nickel removal.

[0048] In an optional embodiment, the analytical solution after the seventh transition treatment is subjected to a pressurization treatment and then subjected to selective nickel removal using an ion exchange resin.

[0049] The beneficial effects of the present disclosure include:

[0050] The present invention discloses a method for subjecting the iron phosphate wash water to be treated to precision membrane filtration, electrocoagulation reaction, laminated filtration, bag filtration, acidic ultrafiltration, cation exchange, security filtration and primary acidic reverse osmosis treatment. It can effectively recover the pure water in the wash water generated in the iron phosphate preparation process under acidic conditions without adjusting the pH value, thereby forming a resource-based circular comprehensive utilization. The entire treatment process does not introduce new ions to interfere with the entire production system, and is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0052] FIG1 is a process flow chart of a method for recycling wash water in a process for preparing ferrophosphate from a nickel-iron alloy provided in Example 1 of the present disclosure;

[0053] FIG2 is a process flow chart of the method for resource utilization of wash water in the process of preparing ferrophosphate from nickel-iron alloy provided in Comparative Example 1 of the present disclosure. DETAILED DESCRIPTION

[0054] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions in the embodiments of the present disclosure are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer were followed. Reagents or instruments used where the manufacturer is not specified are conventional products that can be purchased commercially.

[0055] The resource recovery treatment method for wash water in the process of preparing ferric phosphate from nickel-iron alloy provided by the present invention is described in detail below. It should be noted that the equipment, instruments and other products involved in the following content can be purchased on the market.

[0056] The present disclosure proposes a method for resource recovery of wash water in the process of preparing ferrophosphate from nickel-iron alloy, comprising the following steps:

[0057] The iron phosphate wash water to be treated is subjected to precision membrane filtration to obtain the first intermediate wash water; the first intermediate wash water is subjected to electric flocculation reaction to obtain the second intermediate wash water; the second intermediate wash water is subjected to stacking filtration, bag filtration and acid ultrafiltration in sequence to obtain the third intermediate wash water; the third intermediate wash water is subjected to cation exchange to obtain the fourth intermediate wash water; the fourth intermediate wash water is subjected to security filtration and then subjected to primary acid reverse osmosis treatment.

[0058] In some embodiments, prior to precision membrane filtration, the ferric phosphate wash water to be treated may be subjected to a first transition treatment. This first transition treatment can ensure that the ferric phosphate wash water subjected to precision membrane filtration contains uniform ion species and ion contents. It should be noted that in other embodiments, the first transition treatment may be omitted, and the ferric phosphate wash water to be treated may be directly subjected to precision membrane filtration.

[0059] For reference, the iron phosphate washing water to be treated can be first passed into a first transition treatment container (such as a treatment box, treatment tank, treatment bottle or treatment barrel, etc.) and stay there for a period of time so that the iron phosphate washing water contains uniform ion types and ion content.

[0060] In some embodiments, the volume of the first transition treatment container can be, for example, 1 m 3 , the processing capacity can be 500L / h. In other embodiments, the volume and processing capacity of the first transition processing container can be adaptively adjusted according to actual needs.

[0061] The washing water after the first transition treatment can have the following characteristics: pH value is 1.5-3, conductivity ≤5000us / cm, SS ≤1000mg / L, Ni 2+ ≤500mg / L, Fe 2+ ≤100mg / L, P≤100mg / L.

[0062] Subsequently, the wash water after the first transition treatment is subjected to a pressurization treatment and then to precision membrane filtration. For reference, the pressurization treatment can be achieved by a booster pump.

[0063] In the present disclosure, precision membrane filtration is performed in a precision membrane filter, and the precision thereof can be 0.1 μm-0.5 μm, such as 0.1 μm, 0.3 μm or 0.5 μm.

[0064] In some embodiments, the processing capacity of the precision membrane filter can be 500 L / h, and the membrane area can be 25 m 2 In other embodiments, parameters such as the processing capacity and membrane area of ​​the precision membrane filter can be adaptively adjusted according to actual needs.

[0065] The above-mentioned precision membrane filter is a low-pressure (positive pressure) backwash liquid filtration device. The filtration method of the filter is positive pressure. It uses a filter membrane with surface filtration performance and absolute precision for filtration. Under acidic conditions, all solid particles and suspended matter in the liquid can be retained on the filter membrane surface. It can retain most particles between 0.1μm-0.5μm and 1μm, as well as most suspended matter, bacteria and high molecular weight colloids larger than 1μm, and thus obtain the first intermediate wash water.

[0066] The bottom of the precision membrane filter can automatically discharge waste (such as sludge, etc.) regularly. The waste obtained after the precision membrane filtration except the first intermediate wash water is further subjected to solid-liquid separation to obtain a first liquid and a first solid.

[0067] The solid-liquid separation described above can be performed using plate-and-frame filtration. Accordingly, this process is performed in a plate-and-frame filter press. Specifically, the waste can be pumped into the plate-and-frame filter press via a sludge pump. After the plate-and-frame filtration, the separated first liquid (which can be understood as the filtrate from the plate-and-frame filtration) is returned to the first transition treatment process, specifically, to the first transition treatment vessel. The first solid matter (which can be understood as the filter cake from the plate-and-frame filtration) is returned to the wet leaching process.

[0068] In the present disclosure, the electrocoagulation reaction may be performed in an electrocoagulation reaction tank.

[0069] For reference, direct current can be connected to at least one set of parallel stainless steel plates in the electric flocculation reaction tank. At this time, an electric field is generated between the plates, and the first intermediate wash water to be treated flows into the gaps between the plates. Under this condition, the energized plates will undergo an electrochemical reaction, and metal cations will be generated through the sacrificial anode. After hydrolysis and polymerization, a series of multi-nuclear hydroxyl complexes and hydroxide microflocs are generated, and then the pollutants are removed through the effects of neutralization of charges, adsorption bridging, and net capture and sweeping. At the same time, a reduction reaction occurs at the cathode to produce H2 bubbles with a tiny structure (diameter 17μm-50μm). The bubbles have good adsorption properties, can adhere to particulate pollutants and bring the particulate pollutants to the water surface, which is beneficial to the removal of particulate pollutants from the water.

[0070] In some embodiments, the flocculation product obtained after the electro-flocculation reaction except the second intermediate wash water can be subjected to solid-liquid separation to obtain a second liquid and a second solid.

[0071] Similarly, the solid-liquid separation described above can also be performed using plate-and-frame filtration. Accordingly, this process is performed in a plate-and-frame filter press. Specifically, the flocculated product can be pumped into the plate-and-frame filter press via a booster pump. After plate-and-frame filtration, the separated second liquid (which can be understood as the filtrate from the plate-and-frame filtration) is returned to the first transition treatment process, specifically, to the first transition treatment vessel. The second solid (which can be understood as the filter cake from the plate-and-frame filtration) is returned to the wet leaching process.

[0072] In some embodiments, the second intermediate wash water may be subjected to a second transition treatment in a second transition treatment vessel before the laminate filtration. Subsequently, the intermediate wash water after the second transition treatment is pressurized before the laminate filtration. It should be noted that in other embodiments, the second intermediate wash water may be directly subjected to the laminate filtration without the second transition treatment. However, the second transition treatment is more conducive to achieving better filtration results.

[0073] Similarly, the second transitional treatment container may also be a treatment box, a treatment tank, a treatment bottle or a treatment barrel, etc., and the pressurization treatment may be achieved by a booster pump.

[0074] In the present disclosure, laminated filtration can be performed in a laminated filter, and the corresponding filtration pore size can be 200μm-400μm. It can intercept impurities such as sand with a particle size larger than 200μm-400μm that most precision membrane filters cannot completely filter out. Bag filtration can be performed in a bag filter, and the corresponding filtration pore size can be 50μm-100μm. It can intercept suspended matter with a particle size larger than 50μm-100μm that the laminated filter cannot completely filter out.

[0075] After bag filtration, large suspended solids with a particle size greater than 50μm-100μm are removed, and the remaining intermediate wash water is subjected to acidic ultrafiltration.

[0076] In the present disclosure, acidic ultrafiltration is performed in an acidic ultrafilter having an acidic ultrafiltration membrane. The filtration pore size of the acidic ultrafiltration membrane can be 0.03 μm-0.06 μm, such as 0.03 μm, 0.04 μm, 0.05 μm or 0.06 μm.

[0077] In some embodiments, the processing capacity of the acidic ultrafiltration device can be 500 L / h, and the membrane area of ​​the acidic ultrafiltration membrane can be 25 m 2 In other embodiments, parameters such as the processing capacity and membrane area of ​​the acidic ultrafilter can be adaptively adjusted according to actual needs.

[0078] Since the intermediate wash water entering the acidic ultrafiltration device is acidic in nature, it is pressurized (such as 0.2 MPa). Under this pressure, small molecular solutes and solvents can pass through the acidic ultrafiltration membrane, while large molecular solutes cannot pass through and remain on one side of the membrane, thereby partially purifying the large molecular substances and obtaining the third intermediate wash water (i.e., the water that passes through the acidic ultrafiltration membrane).

[0079] In some embodiments, backwashing (the water used in this portion can be the water in the third transition treatment vessel described below) can be performed to obtain backwash wastewater containing trapped macromolecular substances. The backwash wastewater can be returned to the first transition treatment process, specifically, to the first transition treatment vessel.

[0080] Furthermore, the third intermediate wash water is subjected to cation exchange, which can be carried out in a cation exchanger using a cation exchange resin.

[0081] In some embodiments, the cation exchange resin is a hydrogen-type cation exchange resin (e.g., a hydrogen-type cation exchange resin from the U.S. Dusheng brand). The resin model may be CH-90 or Zhengguang C107 / H. The amount of the resin used may be 200 L to 400 L, such as 200 L, 250 L, 300 L, 350 L, or 400 L. In other embodiments, the amount of the cation exchange resin and other parameters may be adaptively adjusted according to actual needs.

[0082] Most of the nickel, iron and other cations in the third intermediate wash water can be adsorbed and removed by cation exchange to obtain the fourth intermediate wash water.

[0083] Furthermore, the fourth intermediate washing water is subjected to safety filtration to obtain fifth intermediate washing water.

[0084] Safety filtration can be performed using safety filters. Safety filtration intercepts any remaining particles and impurities exceeding 5μm, reducing the risk of contamination and blockage in the back-end process.

[0085] In some embodiments, the fourth intermediate wash water may undergo a third transition treatment in a third transition treatment vessel before undergoing safety filtration. Subsequently, the intermediate wash water after the third transition treatment is pressurized before undergoing safety filtration. It should be noted that in other embodiments, the fourth intermediate wash water may be directly subjected to safety filtration without undergoing the third transition treatment. However, the third transition treatment is more conducive to achieving better filtration results.

[0086] Similarly, the third transitional treatment container may also be a treatment box, a treatment tank, a treatment bottle or a treatment barrel, etc., and the pressurization treatment may be achieved by an ultrafiltration booster pump.

[0087] In some embodiments, the cation exchanger is backwashed with water from the third transition treatment vessel to obtain exchanger flushing water, which is returned to the first transition treatment process, specifically, to the first transition treatment vessel.

[0088] Furthermore, the fifth intermediate wash water is subjected to a pressurization treatment and then to a primary acidic reverse osmosis treatment to obtain a sixth intermediate wash water and concentrated water.

[0089] The pressurization treatment can be achieved by a high-pressure pump. The primary acidic reverse osmosis treatment can be performed in a primary acidic reverse osmosis system having a reverse osmosis membrane.

[0090] In some embodiments, the reverse osmosis membrane used in the primary acidic reverse osmosis process may be RO-BW30-4040 or BW30-8040; the membrane area of ​​the RO-BW30-4040 reverse osmosis membrane may be 8.7 m 2 / , the membrane area of ​​BW30-8040 reverse osmosis membrane can be 37m 2 In other embodiments, parameters such as the membrane area of ​​the reverse osmosis membrane can be adaptively adjusted according to actual needs.

[0091] The pore size of the above reverse osmosis membrane is very small, and under acidic conditions, it can effectively remove dissolved salts, colloids, microorganisms and organic matter in water.

[0092] In some embodiments of the present disclosure, the sixth intermediate wash water obtained after the primary acidic reverse osmosis treatment can be directly recycled. In some other embodiments, the sixth intermediate wash water obtained above can be subjected to a secondary acidic reverse osmosis treatment to obtain recycled water.

[0093] In some embodiments, the sixth intermediate wash water is first subjected to a fourth transition treatment in a fourth transition treatment vessel, and then subjected to a secondary acidic reverse osmosis treatment. It should be noted that in other embodiments, the sixth intermediate wash water may be directly subjected to a secondary acidic reverse osmosis treatment without undergoing the fourth transition treatment.

[0094] Similarly, the fourth transition processing container may also be a processing box, a processing tank, a processing bottle or a processing barrel, etc.

[0095] The two-stage acidic reverse osmosis treatment may be performed in a two-stage acidic reverse osmosis system having a reverse osmosis membrane.

[0096] In some embodiments, the reverse osmosis membrane used in the secondary acidic reverse osmosis process may be RO-BW30LE-4040 or BW30LE-8040; the membrane area of ​​the RO-BW30LE-4040 reverse osmosis membrane may be 8.7 m 2 / , the membrane area of ​​BW30LE-8040 reverse osmosis membrane can be 37m 2 / branch.

[0097] Through secondary acidic reverse osmosis treatment, further desalination and purification can be achieved to obtain recycled water that meets the requirements of the production line.

[0098] For reference, the total content of sulfuric acid and phosphoric acid in the recycled water is ≤ 200 mg / L, and the recycled water does not contain metal ion impurities (including nickel, iron, etc.). The recycled water can be used, by way of example but not limitation, to wash the iron phosphate slurry.

[0099] In the present disclosure, the concentrated water obtained after the primary acidic reverse osmosis treatment may be subjected to acidic concentrated water reverse osmosis treatment to obtain the seventh intermediate wash water and intermediate concentrated water.

[0100] In some embodiments, prior to the acidic brine reverse osmosis treatment, the brine may undergo a fifth transition treatment in a fifth transition treatment vessel. The brine after the fifth transition treatment is then pressurized and subsequently subjected to the acidic brine reverse osmosis treatment. It should be noted that in other embodiments, the brine may be directly subjected to the acidic brine reverse osmosis treatment without the fifth transition treatment.

[0101] Similarly, the fifth transition processing container can also be a processing box, a processing tank, a processing bottle or a processing barrel, etc., and the pressurization treatment can be achieved by a high-pressure pump.

[0102] The above-mentioned acidic concentrated water reverse osmosis treatment can be carried out in a seawater desalination reverse osmosis membrane system that is acid-resistant and high-pressure-resistant.

[0103] In some embodiments, the reverse osmosis membrane used in the acidic concentrated water reverse osmosis treatment process may be RO-SW30HR-4040 or SW30HR-8040; the membrane area of ​​the RO-SW30HR-4040 reverse osmosis membrane may be 8.7 m 2 / , the membrane area of ​​SW30HR-8040 reverse osmosis membrane can be 37m 2 In other embodiments, parameters such as the membrane area of ​​the reverse osmosis membrane can be adaptively adjusted according to actual needs.

[0104] The above-mentioned seawater desalination reverse osmosis membrane can further concentrate and separate the concentrated water.

[0105] The seventh intermediate wash water obtained by the acidic concentrated water reverse osmosis treatment can be used to return to the security filtration treatment process, specifically, can be returned to the third transition treatment container.

[0106] The intermediate concentrated water obtained by reverse osmosis treatment of acidic concentrated water can be partially used to analyze the resin used in the cation exchange process to obtain an analytical solution, which is a salt solution with high concentrations of nickel and iron ions.

[0107] In some embodiments, the intermediate concentrate may first undergo a sixth transition treatment in a sixth transition treatment vessel, followed by filtration through a precision filter to remove any remaining suspended matter, such as particulate impurities with a particle size of 5 μm or greater. A portion of the intermediate concentrate may then be used for desorption on a cation exchange resin. It should be noted that in other embodiments, the intermediate concentrate may be directly filtered through a precision filter without undergoing the sixth transition treatment.

[0108] Similarly, the sixth transition treatment vessel can also be a treatment box, treatment tank, treatment bottle, or treatment barrel. The intermediate concentrated water after the sixth transition treatment is first pressurized and then filtered through a precision filter. In this process, the pressurization can be achieved by a booster pump. The solution obtained after filtration through the precision filter is a mixed dilute acid of sulfuric acid and phosphoric acid. This dilute acid solution is used to regenerate and resolve the resin (for example, the sulfuric acid in the dilute acid solution can be used primarily to regenerate and resolve the resin), achieving resource utilization.

[0109] Furthermore, the analysis liquid obtained after the analysis by the cation exchange resin is subjected to selective nickel removal by the ion exchange resin.

[0110] For reference, the resin used for selective nickel removal by ion exchange resin may be a selective hydrogen-type ion exchange resin, which can directly selectively adsorb nickel under a suitable acidic environment.

[0111] In some embodiments, the resin used for selective nickel removal by ion exchange resin may be of model CH-92, and its dosage may be 200L-400L, such as 200L, 250L, 300L, 350L or 400L, etc. Its brand may be American Dusheng. The selective adsorption capacity of the ion exchange resin for some cations is as follows: Cu 2+ >Pb 2+ >Ni 2+ >Zn 2+ >Cd 2+ >Fe 2+ >Mn 2+ >Ca 2+ >Mg 2+ >Ba 2+ >>Na + Wherein, “>” means “greater than” and “>>” means “much greater than”. In other embodiments, the amount of the ion exchange resin and other parameters can be adaptively adjusted according to actual needs.

[0112] The remaining intermediate concentrated water (excluding the portion subjected to decomposition by the cation exchange resin) obtained by filtration is subjected to decomposition by the ion exchange resin for selective nickel removal to obtain a nickel sulfate decomposition solution and a nickel-removed solution.

[0113] The nickel sulfate solution is evaporated, concentrated and crystallized to obtain a nickel sulfate product; the nickel-removed solution is impurity-removed and recycled to the wet leaching process.

[0114] In some embodiments, the analytical solution may be subjected to the seventh transition treatment before selective nickel removal. It should be noted that in other embodiments, the analytical solution may be directly subjected to the ion exchange resin for selective nickel removal without the seventh transition treatment.

[0115] Similarly, the seventh transition processing container can also be a processing box, a processing tank, a processing bottle or a processing barrel, etc., and the pressurization treatment can be achieved by a booster pump.

[0116] As mentioned above, in the present disclosure, precision membrane filtration is mainly used to intercept most particles between 0.1μm-0.5μm and 1μm, as well as most suspended matter, bacteria, and high molecular weight colloids larger than 1μm under acidic conditions; the electrocoagulation reaction is mainly used to enhance the flocculation effect, so that smaller particles are flocculated and become larger and then filtered and removed; the laminated filtration is mainly used to intercept impurities such as sand with a particle size larger than 200μm-400μm that most precision membrane filters have not been able to completely filter out, thereby protecting the ultrafiltration membrane system; the bag filtration is mainly used to further intercept suspended matter with a particle size larger than 50μm-100μm that the laminated filter has not been able to completely filter out, thereby protecting the ultrafiltration membrane system; cation exchange is used to adsorb metal ions such as nickel and iron in recycled water; security filtration is used to further intercept possible particles and impurities with a particle size larger than 5μm, thereby protecting the reverse osmosis membrane system; the primary acidic reverse osmosis treatment is used for desalination, so that most ions in the water are intercepted; the secondary acidic reverse osmosis treatment is used for further desalination and purification to obtain pure water without metal ions.

[0117] The features and performance of the present disclosure are further described in detail below with reference to the embodiments.

[0118] Example 1

[0119] This embodiment provides a method for resource recovery of wash water in a process of preparing ferrophosphate from a nickel-iron alloy, as shown in FIG1 , comprising the following steps:

[0120] S1: Collect the iron phosphate washing water to be treated in the first transition treatment box (wash water collection box, volume 1m 3 , processing capacity of 500L / h) for 4h to obtain the iron phosphate washing water to be treated with relatively uniform ion types and ion contents (pH value of 1.5-3, conductivity ≤5000us / cm, SS ≤1000mg / L, Ni 2+ ≤500mg / L, Fe 2+ ≤100mg / L, P≤100mg / L).

[0121] The iron phosphate washing water is the water collected after the iron phosphate slurry is washed with pure water in the iron phosphate synthesis process section and passed through a filter press.

[0122] S2: The iron phosphate wash water to be treated in the first transition treatment box (wash water collection box) is pumped into the precision membrane filter system through a booster pump (raw water booster pump) (the precision filter used in the precision membrane filter system has a processing capacity of 500L / h, a filtration accuracy of 0.1μm, and a membrane area of ​​25m2 ) to obtain the first intermediate wash water. The bottom of the precision membrane filter automatically discharges waste at regular intervals. The discharged waste is pumped into a plate and frame filter press for separation into a first liquid and a first solid. The first liquid is returned to the first transition treatment tank, and the first solid is packaged and returned to the wet leaching process.

[0123] S3: electrify the electrode plates in the electro-flocculation reaction tank (50 cm×50 cm×20 cm), and pass the first intermediate washing water into the gaps between the electrode plates to obtain the second intermediate washing water and flocculation products.

[0124] The flocculated product is pumped into a plate and frame filter press for separation to produce a second liquid (clear liquid) and a second solid (cake); the second liquid is returned to the first transition treatment tank (wash water collection tank), and the second solid is packaged and returned to the wet leaching process section.

[0125] S4: The second intermediate washing water is collected in the second transition treatment tank (pretreatment water tank, volume 1m 3 , processing capacity is 500L / h) for buffering for 2h, then the intermediate washing water after the second transition treatment is pumped into the laminated filter (filtration pore size is 200μm) through the booster pump for laminated filtration, and then filtered in the bag filter (filtration pore size is 50μm).

[0126] S5: The intermediate washing water after bag filter filtration is passed into the acid ultrafiltration system (the processing capacity of the acid ultrafiltration system is 500L / h, the filtration pore size of the acid ultrafiltration membrane is 0.03μm, and the membrane area of ​​the acid ultrafiltration membrane is 25m 2 ) to perform acidic ultrafiltration to obtain a third intermediate wash water.

[0127] S6: The third intermediate wash water is subjected to cation exchange in a cation exchanger (the cation exchange resin is hydrogen-type cation exchange resin CH-90 of the American Dusheng brand; the amount of the resin used is 200 L) to obtain a fourth intermediate wash water.

[0128] S7: Collect the fourth intermediate washing water in the third transition treatment tank (ultrafiltration UF water tank with a volume of 1m 3 , the processing capacity is 500L / h) and buffered for 2h. Subsequently, the intermediate washing water after the third transition treatment is pumped into the safety filter (RO1 safety filter, the filter pore size is 5μm) through a booster pump (ultrafiltration booster pump) for safety filtration to obtain the fifth intermediate washing water.

[0129] The water in the ultrafiltration UF water production tank can be used to backwash the acidic ultrafilter and the cation exchanger, and the backwash drainage obtained from the acidic ultrafilter and the exchanger washing water obtained from the cation exchanger are returned to the first transition treatment tank.

[0130] S8: The fifth intermediate wash water is pumped into the first-stage acidic reverse osmosis system (acidic RO1 reverse osmosis system, the reverse osmosis membrane used in the first-stage acidic reverse osmosis process is RO-BW30-4040; the membrane area of ​​the reverse osmosis membrane is 8.7m 2 / branch) to carry out a primary acidic reverse osmosis treatment to obtain a sixth intermediate wash water and concentrated water.

[0131] S9: The sixth intermediate washing water is collected in the fourth transition treatment tank (RO1 water tank, volume 1m 3 , with a processing capacity of 500 L / h) for 2 hours, and then passed into a secondary acidic reverse osmosis system (RO2 reverse osmosis system, the reverse osmosis membrane used in the secondary acidic reverse osmosis process is RO-BW30LP-4040; the membrane area of ​​the reverse osmosis membrane is 8.7m 2 / branch) to perform secondary acidic reverse osmosis treatment to obtain recycled water (the total content of sulfuric acid and phosphoric acid is ≤ 200 mg / L, and the recycled water does not contain metal ion impurities).

[0132] The recycled water is collected in the RO2 water production tank and then used to wash the iron phosphate slurry through the pure water supply system.

[0133] S10: The concentrated water obtained after the primary acidic reverse osmosis treatment is collected in the fifth transition treatment tank (RO1 concentrated water collection tank, with a volume of 1m 3 , with a processing capacity of 500L / h) for 2h, and then pumped into the acid-resistant and high-pressure resistant seawater desalination reverse osmosis membrane system (acidic concentrated water RO reverse osmosis system, the reverse osmosis membrane used in this system is RO-SW30HR-4040; the membrane area of ​​the reverse osmosis membrane is 8.7m 2 / branch) to carry out reverse osmosis treatment on the acidic concentrated water to obtain the seventh intermediate washing water and intermediate concentrated water.

[0134] S11: The seventh intermediate wash water is collected in the concentrated water RO production tank, and then returned to the third transition treatment container (ultrafiltration UF production tank) as needed.

[0135] S12: Collect the intermediate concentrated water in the sixth transition treatment tank (concentrated water RO concentrated water tank with a volume of 0.5m 3 , processing capacity is 200L / h) and buffered for 1h. Subsequently, it is pumped into a precision filter (with a filter pore size of 5μm) through a booster pump for filtration to obtain a mixed dilute acid of sulfuric acid and phosphoric acid (≈50g / L dilute acid).

[0136] S13: Pump a portion of the mixed dilute acid into the cation exchanger in S6 through a sulfuric acid booster pump to decompose the cation exchange resin to obtain a decomposition solution.

[0137] S14: Collect the analytical solution in the seventh transition treatment box (analytical solution collection box, volume 0.2m 3 , processing capacity is 50L / h) for buffering for 4h, and then pumped into the ion exchange resin selective nickel removal system (the ion exchange resin used is CH-92 from Dusheng of the United States, and its dosage is 200L) through a booster pump (analysis liquid booster pump) for selective nickel removal.

[0138] S15: When the ion exchange resin in S14 is saturated with adsorption, the remaining mixed dilute acid except for the part of the mixed dilute acid used in S13 is used to decompose the saturated ion exchange resin to obtain a nickel sulfate decomposition solution and a nickel-removed solution (iron salt and phosphate solution).

[0139] S16: The nickel sulfate solution is evaporated, concentrated and crystallized (MVR for short) to obtain a nickel sulfate product, which is recovered for later use.

[0140] S17: The nickel-removed liquid is subjected to impurity removal and recycled to the wet leaching process.

[0141] Example 2

[0142] The difference between this embodiment and Example 1 is that the filtration accuracy of the precision membrane filter is 0.5μm, the filtration pore size of the laminated filtration is 400μm, the filtration pore size of the bag filtration is 100μm, the filtration pore size of the acidic ultrafiltration membrane is 0.06μm, the cation exchange resin used for cation exchange is Zhengguang C107 / H and its dosage is 400L, and the dosage of the resin used in the selective nickel removal process of the ion exchange resin is 400L.

[0143] Example 3

[0144] The difference between this embodiment and embodiment 1 is that the filtration accuracy of the precision membrane filter is 0.3 μm, the filtration pore size of the laminated filter is 300 μm, the filtration pore size of the bag filter is 80 μm, the filtration pore size of the acidic ultrafiltration membrane is 0.05 μm, the amount of cation exchange resin used for cation exchange is 300 L, and the amount of resin used in the selective nickel removal process of the ion exchange resin is 300 L. The model of the reverse osmosis membrane used in the first-stage acidic reverse osmosis process is BW30-8040, the model of the reverse osmosis membrane used in the second-stage acidic reverse osmosis process is BW30LE-8040, and the model of the reverse osmosis membrane used in the acidic concentrated water reverse osmosis treatment process is SW30HR-8040. Comparative Example 1

[0145] This comparative example provides a method for resource utilization of wash water in the preparation of ferrophosphate from nickel-iron alloy, as shown in FIG2 , and the method is as follows:

[0146] S1 is the same as Example 1.

[0147] S2: The untreated iron phosphate wash water in the first transition tank (wash water collection tank) is pumped into a sedimentation tank (with sodium hydroxide and calcium hydroxide added, respectively, to a pH of 11.0) via a booster pump (raw water booster pump). Most nickel, iron, and phosphorus ions are precipitated and removed. The supernatant is filtered through a plate and frame filter press, and the filtered water enters the pretreatment water tank. The sediment at the bottom of the sedimentation tank is pumped into a plate and frame filter press for separation, producing a clear liquid and a cake. The clear liquid is returned to the wash water collection tank.

[0148] The water in the pre-treatment water tank is adjusted to pH 7.0 by adding sulfuric acid, and then pumped into the precision membrane filter system through the booster pump (the precision filter used in the precision membrane filter system has a processing capacity of 500L / h, a filtration accuracy of 0.1μm, and a membrane area of ​​25m 2 ) for filtration, and the bottom of the precision membrane filter automatically discharges waste regularly. The discharged waste enters the plate and frame filter press through the sludge pump for separation into the first liquid (clear liquid) and the first solid (cake); the first liquid is returned to the wash water collection tank, and the first solid is packaged and transported out.

[0149] S3: The filtrate from the precision membrane filter enters the bag filter for filtration.

[0150] S4: The liquid filtered by the bag filter is passed into the acid ultrafilter (ultrafiltration system, the processing capacity of the acid ultrafilter is 500L / h, the filtration pore size of the acid ultrafiltration membrane is 0.03μm, and the membrane area of ​​the acid ultrafiltration membrane is 25m 2 ) was subjected to acidic ultrafiltration.

[0151] Subsequently, steps S7 to S10 of Example 1 were performed (the RO1 and RO2 reverse osmosis systems used in this process were both conventional non-acidic reverse osmosis systems). The recovered water obtained in S9 had a conductivity of ≤10 μs / cm and a pH of 6.0-8.0 and was used to wash the ferric phosphate slurry. The pure water obtained from the concentrated water reverse osmosis treatment was returned to the ultrafiltration water tank, and the concentrated water was evaporated, concentrated, and crystallized to obtain sodium sulfate solid.

[0152] Test example

[0153] Comparing some of the data related to the treatment of iron phosphate washing wastewater in Example 1 and Comparative Example 1, the treatment of 1m 3 The iron phosphate washing water solution is calculated according to the market price: electricity fee is 0.65 yuan / KW.H, water fee is 4.5 yuan / t, and the results are shown in Table 1.

[0154] Table 1 Comparison results

[0155] As shown in Table 1, the equipment operating costs and safety risks of Example 1 are low. In Comparative Example 1, because the material is adjusted and precipitated, there is no ion exchanger, and the system is very prone to membrane blockage, resulting in a higher operation and maintenance risk. Example 1 has greater promotion value than Comparative Example 1.

[0156] In summary, the resource recovery treatment method for washing water in the process of preparing ferric phosphate from nickel-iron alloy provided in the present invention can effectively recover the pure water in the ferric phosphate washing water, solve the problem of discharge and disposal of washing water wastewater in ferric phosphate, and form a resource recovery cycle and comprehensive utilization. The entire treatment process does not introduce new ions to interfere with the entire production system, is green and environmentally friendly, and has low cost. Industrial Applicability

[0157] The resource recovery treatment method for wash water in the process of preparing ferric phosphate from nickel-iron alloy provided in the present disclosure is to subject the wash water to be treated in the process of preparing ferric phosphate to precision membrane filtration, electrocoagulation reaction, laminated filtration, bag filtration, acid ultrafiltration, cation exchange, security filtration, primary acidic reverse osmosis treatment and secondary acidic reverse osmosis treatment and other operations. It can effectively recover pure water in the ferric phosphate wash water under acidic conditions throughout the process without adjusting the pH value, thereby solving the problem of discharge and disposal of wash water wastewater in ferric phosphate and forming resource recovery and recycling comprehensive utilization. The entire treatment process does not introduce new ions to interfere with the entire production system, is green and environmentally friendly, and has low cost.

Claims

1. A method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy, characterized in that: The following steps are involved: The iron phosphate wash water to be treated is subjected to precision membrane filtration to obtain the first intermediate wash water; the first intermediate wash water is subjected to electric flocculation reaction to obtain the second intermediate wash water; the second intermediate wash water is subjected to stack filtration, bag filtration and acid ultrafiltration in sequence to obtain the third intermediate wash water; the third intermediate wash water is subjected to cation exchange to obtain the fourth intermediate wash water; the fourth intermediate wash water is subjected to security filtration and then subjected to primary acid reverse osmosis treatment.

2. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to claim 1, characterized in that: Before the precision membrane filtration is performed, the iron phosphate washing water to be treated is also subjected to a first transition treatment; The pH value of the washing water after the first transition treatment is 1.5-3, the conductivity is ≤5000us / cm, the suspended matter content is ≤1000mg / L, Ni 2+ ≤500mg / L, Fe 2+ ≤100mg / L, P≤100mg / L.

3. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to claim 2, characterized in that: The wash water after the first transition treatment is pressurized and then filtered through a precision membrane.

4. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to any one of claims 1 to 3, characterized in that: The filtration accuracy of the precision membrane filter used in the precision membrane filtration process is 0.1 μm-0.5 μm.

5. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to any one of claims 1 to 4, characterized in that: The discarded matter obtained after the precision membrane filtration except the first intermediate washing water is subjected to solid-liquid separation to obtain a first liquid and a first solid matter; using the first liquid to return to the first transition process; The first solids are used to return to the wet leaching process.

6. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to any one of claims 1 to 5, characterized in that: The flocculation products obtained after the electro-flocculation reaction except the second intermediate washing water are subjected to solid-liquid separation to obtain a second liquid and a second solid; using the second liquid to return to the first transition process; The second solids are used to return to the wet leaching process.

7. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to any one of claims 1 to 6, characterized in that: The filter pore size of the laminated filter is 200 μm-400 μm, or the filter pore size of the bag filter is 50 μm-100 μm.

8. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to any one of claims 2 to 7, characterized in that: Before the stacked filtration is performed, the second intermediate wash water is subjected to a second transition treatment.

9. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to claim 8, characterized in that the intermediate wash water after the second transition treatment is pressurized and then subjected to lamination filtration.

10. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to any one of claims 1 to 9, characterized in that: The filtration pore size of the acidic ultrafiltration membrane used in the acidic ultrafiltration process is 0.03 μm-0.06 μm.

11. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to any one of claims 1 to 10, characterized in that: The cation exchange resin used for cation exchange has at least one of the following characteristics: Feature 1: The cation exchange resin is a hydrogen-type cation exchange resin; Feature 2: The resin model is CH-90 or Zhengguang C107 / H; Feature 3: The amount of resin used is 200L-400L.

12. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to any one of claims 8 to 11, characterized in that: Before the security filtration, the fourth intermediate washing water is subjected to a third transition treatment.

13. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to claim 12, characterized in that: The intermediate wash water after the third transition treatment is subjected to pressurization treatment and then safety filtration to obtain the fifth intermediate wash water.

14. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to any one of claims 1 to 13, characterized in that: The fifth intermediate wash water is subjected to a primary acidic reverse osmosis treatment after being subjected to a pressurization treatment.

15. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to any one of claims 1 to 14, characterized in that: The reverse osmosis membrane used in the primary acidic reverse osmosis process is RO-BW30-4040 or BW30-8040.

16. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to claim 15, characterized in that: After the primary acidic reverse osmosis treatment, the sixth intermediate wash water and concentrated water are obtained, and the sixth intermediate wash water is subjected to secondary acidic reverse osmosis treatment to obtain recycled water.

17. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to claim 16, characterized in that: The sixth intermediate wash water is first subjected to the fourth transition treatment and then subjected to the secondary acidic reverse osmosis treatment to obtain recycled water.

18. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to claim 16 or 17, characterized in that: The reverse osmosis membrane used in the secondary acidic reverse osmosis process is RO-BW30LE-4040 or BW30LE-8040.

19. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to any one of claims 16 to 18, characterized in that: The total content of sulfuric acid and phosphoric acid in the recycled water is ≤200 mg / L, and the recycled water does not contain metal ion impurities.

20. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to any one of claims 16 to 19, characterized in that: The recovered water is used for washing the iron phosphate slurry.

21. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to any one of claims 16 to 20, characterized in that: The concentrated water obtained after the primary acidic reverse osmosis treatment is subjected to acidic concentrated water reverse osmosis treatment to obtain the seventh intermediate wash water and intermediate concentrated water. The seventh intermediate wash water is used to return to the security filtration treatment process; the intermediate concentrated water is used to analyze the resin used in the cation exchange process.

22. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to claim 21, characterized in that: The reverse osmosis membrane used in the reverse osmosis treatment of acidic concentrated water is RO-SW30HR-4040 or SW30HR-8040.

23. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to claim 21 or 22, characterized in that: Before the acidic concentrated water is subjected to reverse osmosis treatment, the concentrated water is subjected to a fifth transition treatment.

24. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to claim 23, characterized in that: The intermediate wash water after the fifth transition treatment is subjected to a pressurization treatment and then to an acidic concentrated water reverse osmosis treatment to obtain the seventh intermediate wash water.

25. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to claim 23 or 24, characterized in that: The intermediate concentrated water is first filtered through a precision filter and then used to analyze the cation exchange resin.

26. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to claim 25, characterized in that: Before being filtered through a precision filter, the intermediate concentrated water is subjected to a sixth transition treatment.

27. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to claim 26, characterized in that: The concentrated water after the sixth transition treatment is pressurized and then filtered through a precision filter.

28. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to any one of claims 25 to 27, characterized in that: Part of the intermediate concentrated water obtained by filtering through a precision filter is subjected to analysis with a cation exchange resin, and the analyzed solution is subjected to selective nickel removal with an ion exchange resin. The remaining intermediate concentrated water obtained by filtering through a precision filter is subjected to analysis with an ion exchange resin for selective nickel removal to obtain a nickel sulfate analysis solution and a nickel-removed solution; the nickel sulfate analysis solution is evaporated, concentrated, and crystallized to obtain a nickel sulfate product; the nickel-removed solution is subjected to impurity removal and recovered to a wet leaching process.

29. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to claim 28, characterized in that: The resin used in the selective nickel removal process of the ion exchange resin has at least one of the following characteristics: Feature 1: The resin model is CH-92; Feature 2: The amount of resin used is 200L-400L.

30. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to claim 28 or 29, characterized in that: Before selective nickel removal, the analytical solution is subjected to a seventh transition treatment.

31. The method for recycling wash water in the process of preparing ferrophosphate from nickel-iron alloy according to claim 30, characterized in that: The analytical solution after the seventh transition treatment is subjected to a pressurization treatment and then subjected to ion exchange resin for selective nickel removal.

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