Method for recycling iron-aluminum slag

Abstract

The invention provides an iron and aluminum slag resource recycling method which comprises the following steps: carrying out microwave treatment on iron and aluminum slag, then carrying out acid dissolution to obtain an acid solution, and carrying out neutralization precipitation reaction on the acid solution to obtain a neutralized mother solution and first solid-phase slag; performing waste gas treatment on the first waste gas generated by the microwave treatment to obtain a sulfuric acid solution and fluoride; the neutralization mother liquor is subjected to neutralization nickel and cobalt precipitation treatment, nickel and cobalt precipitation and nickel and cobalt precipitation mother liquor are obtained, the nickel and cobalt precipitation mother liquor is subjected to ammonium phosphate precipitation treatment, and an ammonium phosphate compound is obtained; the first solid-phase slag is subjected to alkaline leaching treatment, and alkaline leaching liquid and second solid-phase slag are obtained; carrying out neutralization aluminum precipitation treatment on the alkaline leaching solution to obtain aluminum hydroxide and an aluminum precipitation mother solution; the second solid-phase slag is subjected to acid leaching treatment, and acid leaching liquid and ferric hydroxide are obtained; and the acid leaching solution is subjected to neutralization manganese precipitation treatment, and manganese hydroxide and manganese precipitation mother liquor are obtained. By means of the method, iron, aluminum, nickel, cobalt, manganese, phosphorus, sulfur, fluorine and other elements in the iron-aluminum slag can be fully recycled, and harmless and recycling treatment of solid waste is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of battery recycling, and relates to a method for recycling iron-aluminum slag. BACKGROUND

[0002] With the improvement and maturity of new energy automobile technology, the number of lithium ion battery power vehicles continues to rise. Limited by the service life of power batteries, the number of scrapped power batteries is also increasing, making the power battery recycling industry grow rapidly. The waste battery recycling process generally adopts a wet process, including pretreatment, leaching, impurity removal and extraction steps. A large amount of iron-aluminum slag is generated in the leaching and impurity removal stage. At present, the iron-aluminum slag is mainly treated by landfill. However, on the one hand, the landfill treatment occupies land resources, and on the other hand, valuable metal elements such as iron, aluminum, nickel, cobalt and manganese are not fully recycled and utilized.

[0003] Therefore, it is urgent to provide a method for recycling iron-aluminum slag, so as to realize the recycling of valuable metal elements such as iron, aluminum, nickel, cobalt and manganese, and reduce the disposal cost of iron-aluminum slag. SUMMARY

[0004] The purpose of the application is to provide a method for recycling iron-aluminum slag, which aims to solve the disposal problem of iron-aluminum slag generated in the lithium battery recycling process, fully recycle elements such as iron, aluminum, nickel, cobalt, manganese, phosphorus, sulfur and fluorine in the iron-aluminum slag, and realize the harmless and resourceful disposal of solid waste.

[0005] To achieve this application purpose, the following technical solutions are adopted:

[0006] The application provides a method for recycling iron-aluminum slag, which comprises the following steps:

[0007] (1) The iron-aluminum slag is treated by microwave and then subjected to acid dissolution to obtain an acid solution, and the acid solution is subjected to neutralization precipitation to obtain a neutralization mother liquor and a first solid phase slag;

[0008] The first waste gas generated by the microwave treatment is subjected to waste gas treatment to obtain a sulfuric acid solution and a fluoride;

[0009] (2) The neutralization mother liquor in step (1) is subjected to nickel-cobalt precipitation treatment to obtain a nickel-cobalt precipitate and a nickel-cobalt precipitation mother liquor, and the nickel-cobalt precipitation mother liquor is subjected to phosphorus-ammonium precipitation treatment to obtain a crystallization mother liquor and an ammonium phosphate compound;

[0010] The first solid phase slag in step (1) is subjected to alkali leaching treatment to obtain an alkali leaching solution and a second solid phase slag;

[0011] (3) The alkali leaching solution in step (2) is subjected to aluminum precipitation treatment to obtain aluminum hydroxide and an aluminum precipitation mother liquor;

[0012] The second solid phase residue in step (2) is subjected to acid leaching treatment to obtain an acid leaching liquid and a third solid phase residue;

[0013] (4) The third solid phase residue in step (3) is dried to obtain iron hydroxide;

[0014] The acid leaching liquid in step (3) is subjected to neutralization and manganese precipitation treatment to obtain manganese hydroxide and a manganese precipitation mother liquor, and the recovery of iron, aluminum, phosphorus, sulfur, fluorine, nickel, cobalt and manganese elements in the iron and aluminum residue is completed.

[0015] The present application realizes the resource utilization of the iron and aluminum residue through microwave treatment, acid dissolution, acid leaching, neutralization and precipitation and alkali leaching, reduces the disposal cost of the iron and aluminum residue in the lithium battery recycling process, and reduces the occupation of land resources; and the present application recovers nickel, cobalt and manganese elements while recovering iron, aluminum, phosphorus, sulfur and fluorine elements, and basically realizes the full element recovery of the iron and aluminum residue.

[0016] Preferably, the temperature of the microwave treatment in step (1) is 500-700 DEG C, for example, it can be 500 DEG C, 525 DEG C, 550 DEG C, 575 DEG C, 600 DEG C, 625 DEG C, 650 DEG C, 675 DEG C or 700 DEG C, and the time is 2-6 h, for example, it can be 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h or 6 h, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0017] The present application can realize the removal of 1-5% of fluorine and sulfur in the iron and aluminum residue by using microwave treatment decomposition technology; the microwave treatment includes the following main reaction equation:

[0018] H2SO4=SO3↑+H2O↑;

[0019] 2AlF3+6H2O=Al2O3+6HF↑+3H2O↑.

[0020] Preferably, the acid solvent used in the acid dissolution in step (1) includes a first water solvent and a first acid liquid.

[0021] Preferably, the first water solvent includes any one or a combination of at least two of production water, distilled water or washing water.

[0022] The method of the present application realizes the cyclic use of distilled water and washing water, no waste water is generated, and zero waste water discharge is achieved.

[0023] Preferably, the mass ratio of the microwave-treated iron-aluminum slag obtained by microwave treatment of iron-aluminum slag in step (1) to the acid solvent is 1:(5-10), for example, it can be 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5 or 1:10, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, the first acid solution comprises industrial hydrochloric acid with a concentration of 15wt% to 30wt%, for example, it may be 15wt%, 18wt%, 20wt%, 25wt% or 30wt%, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0025] Preferably, the pH of the acid dissolution in step (1) is 0.5 to 1, for example, it can be 0.5, 0.6, 0.7, 0.8, 0.9 or 1, and the time is 2 to 4 hours, for example, it can be 2 hours, 2.5 hours, 3 hours, 3.5 hours or 4 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] Preferably, after the acid dissolution in step (1) is completed, a first solid-liquid separation is performed to obtain the acid solution.

[0027] The main reaction equation for acid dissolution in step (1) of this invention is as follows:

[0028] 3HCl + FePO4 = FeCl3 + H3PO4;

[0029] 3HCl + AlPO4 = AlCl3 + H3PO4;

[0030] 6HCl+Mn3(PO4)2=3MnCl2+2H3PO4;

[0031] 6HCl+Co3(PO4)2=3CoCl2+2H3PO4;

[0032] 6HCl+Ni3(PO4)2=3NiCl2+2H3PO4;

[0033] 6HCl + Al₂O₃ = 2AlCl₃ + 3H₂O.

[0034] Preferably, in step (1), the acid solution is subjected to the neutralization and precipitation reaction using an ammonia-based substance under a protective atmosphere.

[0035] Preferably, the ammonia-like substance includes ammonia water and / or ammonia gas, wherein the ammonia water is industrial ammonia water with a concentration of 20wt% to 28wt% (for example, it can be 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt% or 28wt%).

[0036] Preferably, the protective atmosphere comprises nitrogen.

[0037] Preferably, the pH of the neutralization precipitation reaction in step (2) is 10.5 to 11, for example, it can be 10.5, 10.6, 10.7, 10.8, 10.9 or 11, and the time is 0.5h to 2h, for example, it can be 0.5h, 0.8h, 1.1h, 1.4h, 1.7h or 2h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] Preferably, after the neutralization and precipitation reaction in step (1) is completed, a second solid-liquid separation is performed to obtain the neutralization mother liquor and the first solid residue.

[0039] The main reaction equation for the neutralization-precipitation reaction in this invention is as follows:

[0040] NH3 + H2O = NH4OH (ammonia gas is introduced);

[0041] 3NH4OH+AlCl3=Al(OH)3↓+3NH4Cl;

[0042] 3NH4OH+FeCl3=Fe(OH)3↓+3NH4Cl;

[0043] 2NH4OH+MnCl2=Mn(OH)2↓+2NH4Cl;

[0044] 6NH4OH+NiCl2=Ni(NH3)6Cl2+6H2O;

[0045] 6NH4OH+CoCl2=Co(NH3)6Cl2+6H2O.

[0046] This invention cleverly utilizes the characteristic that ammonia reacts with nickel and cobalt ions to form soluble complexes, while forming insoluble substances with other metal elements. Ammonia is added to the filtrate to carry out a neutralization and precipitation reaction, and then a second solid-liquid separation is used to separate nickel and cobalt elements from other metal elements.

[0047] Preferably, the waste gas treatment in step (1) includes passing the first waste gas generated by microwave treatment into a first absorbent liquid, the first absorbent liquid including concentrated sulfuric acid solution, to obtain the sulfuric acid solution and the second waste gas in step (1), the second waste gas being passed into a second absorbent liquid for absorption to obtain an alkaline absorbent liquid, the second absorbent liquid including alkaline solution, the alkaline absorbent liquid being subjected to a first evaporation crystallization treatment to obtain distilled water and fluoride;

[0048] Preferably, the first absorbent comprises a concentrated sulfuric acid solution with a concentration of 70wt% to 95wt%, for example, it may be 70wt%, 75wt%, 80wt%, 85wt%, 90wt%, or 95wt%, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0049] In this invention, the concentration of the first absorbent is maintained in the range of 70wt% to 95wt%. If it exceeds this range, the first absorbent is replaced, and the replaced sulfuric acid solution is sold as a by-product.

[0050] Preferably, the second absorbent comprises industrial liquid alkali with a concentration of 30wt% to 32wt% (e.g., 30wt%, 30.5wt%, 31wt%, 31.5wt%, or 32wt%) or industrial liquid alkali with a concentration of 40wt% to 42wt% (e.g., 40wt%, 40.5wt%, 41wt%, 41.5wt%, or 42wt%).

[0051] Preferably, when the pH of the alkali absorption solution is < 8.5, the alkali absorption solution is subjected to a first evaporation and crystallization treatment to obtain distilled water and sodium fluoride. The distilled water can be reused as production water, and the obtained sodium fluoride can be sold as a by-product.

[0052] The first waste gas generated by microwave treatment in this invention includes sulfur trioxide and hydrogen fluoride. Utilizing the strong hygroscopic properties of concentrated sulfuric acid and the near insolubility of hydrogen fluoride in concentrated sulfuric acid, the first waste gas is passed through concentrated sulfuric acid. The sulfur trioxide and water in the first waste gas react to form sulfuric acid, and excess water is absorbed by the concentrated sulfuric acid, effectively achieving the separation and purification of hydrogen fluoride, sulfur trioxide, and water. The resulting sulfuric acid solution can be sold as a byproduct. The main reaction equation for the absorption of the second waste gas by passing it through an alkaline solution is as follows: NaOH + HF = NaF + H₂O.

[0053] Preferably, hydrochloric acid is added to perform the neutralization and nickel-cobalt precipitation treatment described in step (2).

[0054] Preferably, the pH of the neutralization treatment of nickel and cobalt in step (2) is 8 to 9, for example, 8, 8.2, 8.4, 8.6, 8.8 or 9, and the time is 0.5h to 2h, for example, 0.5h, 0.75h, 1h, 1.25h, 1.5h, 1.75h or 2h, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0055] Preferably, after the neutralization and nickel-cobalt precipitation treatment in step (2) is completed, a third solid-liquid separation is performed to obtain the nickel-cobalt precipitate and the nickel-cobalt precipitate mother liquor.

[0056] The main reaction equation for the neutralization of nickel-cobalt immersion treatment described in this invention is as follows:

[0057] 3Ni(NH3)6 2+ +18H + +2PO4 3- =Ni3(PO4)2↓+18NH4 + ;

[0058] 3Co(NH3)6 2+ +18H + +2PO4 3- =Co3(PO4)2↓+18NH4 + Phosphate ions are derived from iron and aluminum slag.

[0059] This invention neutralizes the soluble complexes of nickel and cobalt with acid to form insoluble phosphate precipitates. After a third solid-liquid separation process, solid residue (nickel phosphate and cobalt phosphate) and nickel-cobalt mother liquor are obtained. The nickel phosphate and cobalt phosphate can be returned to the front-end battery recycling process for further recovery of nickel and cobalt.

[0060] Preferably, magnesium chloride is added to perform the ammonium phosphate precipitation treatment in step (2).

[0061] Preferably, the amount of magnesium chloride added is 0.9 to 1 times the theoretical amount required to convert all phosphate ions into magnesium ammonium phosphate. For example, it can be 0.9 times, 0.92 times, 0.94 times, 0.96 times, 0.98 times or 1 times, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0062] Preferably, the ammonium phosphate precipitation treatment time in step (2) is 0.5h to 2h, for example, it can be 0.5h, 0.75h, 1h, 1.25h, 1.5h, 1.75h or 2h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0063] Preferably, after the ammonium phosphate precipitation treatment in step (2) is completed, a fourth solid-liquid separation is performed to obtain the crystallization mother liquor and magnesium ammonium phosphate.

[0064] The main reaction equation for the ammonium phosphate precipitation treatment described in this invention is as follows:

[0065] Mg 2+ +NH4 + +PO4 3- +6H2O=MgNH4PO4·6H2O↓.

[0066] This invention generates a sparingly soluble complex salt by reacting magnesium ions, ammonium ions, and phosphate ions. After a fourth solid-liquid separation process, a crystallization mother liquor and magnesium ammonium phosphate complex salt are obtained. The magnesium ammonium phosphate complex salt can be sold as a product.

[0067] Preferably, the mother liquor from step (2) undergoes a second evaporation crystallization process to obtain ammonium chloride and distilled water. The distilled water can be reused as production water, and the obtained ammonium chloride can be sold as a by-product.

[0068] Preferably, before the second evaporation crystallization treatment, the mother liquor of the crystallization process in step (2) is first treated with industrial hydrochloric acid with a concentration of 15wt% to 30wt%, for example, 15wt%, 18wt%, 20wt%, 25wt%, or 30wt%, to adjust the pH to 5.5 to 6.5, for example, 5.5, 5.7, 5.9, 6.1, 6.3, or 6.5, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0069] Preferably, the temperature of the second evaporation crystallization process is ≤100℃, for example, it can be 100℃, 90℃, 80℃, 70℃, 60℃ or 50℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0070] Preferably, the alkaline leaching agent used in step (2) includes a second aqueous solvent and liquid alkali, wherein the liquid alkali includes industrial liquid alkali with a concentration of 30% to 32% (e.g., 30wt%, 30.5wt%, 31wt%, 31.5wt%, or 32wt%) or a concentration of 40wt% to 42wt% (e.g., 40wt%, 40.5wt%, 41wt%, 41.5wt%, or 42wt%).

[0071] Preferably, the second aqueous solvent includes any one or a combination of at least two of production water, distilled water, or washing water.

[0072] Preferably, in step (2), the mass ratio of the first solid residue to the alkaline leaching agent is 1:(5-8), for example, it can be 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5 or 1:8, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0073] Preferably, the pH of the alkaline leaching treatment in step (2) is 12.5 to 13.5, for example, it can be 12.5, 12.8, 13, 13.3 or 13.5, and the time is 2h to 5h, for example, it can be 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0074] Preferably, after the alkaline leaching treatment in step (2) is completed, a fifth solid-liquid separation is performed to obtain the alkaline leaching solution and the second solid residue.

[0075] The main reaction equation for the alkaline leaching treatment described in this invention is as follows: NaOH + Al(OH)3 = NaAlO2 + 2H2O. This invention utilizes the amphoteric properties of aluminum, which can be converted into soluble aluminate solution under a strongly alkaline environment, and then achieves the separation of aluminum from other metal elements through the fifth solid-liquid separation process.

[0076] Preferably, the pH of the neutralization and aluminum precipitation treatment in step (3) is 6 to 8, for example, it can be 6, 6.4, 6.8, 7.2, 7.6 or 8, and the time is 0.5h to 2h, for example, it can be 0.5h, 0.75h, 1h, 1.25h, 1.5h, 1.75h or 2h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0077] Preferably, the neutralization and aluminum precipitation treatment in step (3) uses industrial hydrochloric acid with a concentration of 15wt% to 30wt% to adjust the pH, for example, it can be 15wt%, 18wt%, 20wt%, 25wt% or 30wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0078] Preferably, after the neutralization and aluminum precipitation treatment in step (3) is completed, a sixth solid-liquid separation is performed to obtain the aluminum hydroxide and the aluminum precipitation mother liquor.

[0079] The main reaction equation for the neutralization and aluminum precipitation treatment described in this invention is as follows:

[0080] H + +AlO2 - +H2O=Al(OH)3↓.

[0081] This invention converts soluble aluminates into insoluble aluminum hydroxide precipitates by adding acid. After a sixth solid-liquid separation, aluminum mother liquor and aluminum hydroxide are obtained, and the aluminum hydroxide can be sold as a product.

[0082] Preferably, the acid leaching agent used in step (3) includes a third aqueous solvent and a second acid solution.

[0083] Preferably, the third water solvent includes any one or a combination of at least two of production water, distilled water, or washing water.

[0084] Preferably, in step (3), the mass ratio of the second solid residue to the acid leaching agent is 1:(5-10), for example, it can be 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5 or 1:10, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0085] Preferably, the second acid solution comprises industrial hydrochloric acid with a concentration of 15wt% to 30wt%, for example, it may be 15wt%, 18wt%, 20wt%, 25wt% or 30wt%, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0086] Preferably, the pH of the acid leaching treatment in step (3) is 3.5 to 4.2, for example, it can be 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1 or 4.2, and the time is 2h to 4h, for example, it can be 2h, 2.5h, 3h, 3.5h or 4h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0087] Preferably, after the acid leaching treatment in step (3) is completed, a seventh solid-liquid separation is performed to obtain the acid leaching solution and the third solid residue.

[0088] The main reaction equation for the acid leaching treatment in step (3) of this invention is as follows:

[0089] HCl + Mn(OH)2 = MnCl2 + 2H2O.

[0090] This invention cleverly utilizes the different pH precipitation ranges of manganese ion and iron ion hydroxides. Within a certain pH range, manganese hydroxide dissolves into manganese ions, while iron ions remain as insoluble hydroxides. Through the seventh solid-liquid separation, the separation of iron and manganese elements is effectively achieved, thus realizing the purpose of iron purification.

[0091] Preferably, the drying temperature of the third solid slag in step (3) is 120℃~200℃, for example, it can be 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃ or 200℃, and the time is 1h~4h, for example, it can be 1h, 1.5h, 2h, 2.5h, 3h, 3.5h or 4h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0092] The main reaction equation for the drying treatment of the third solid slag of this invention is as follows:

[0093] Fe(OH)3·nH2O=Fe(OH)3+nH2O↑.

[0094] Preferably, the pH of the neutralization and manganese precipitation treatment in step (4) is 8 to 9, for example, it can be 8, 8.2, 8.4, 8.6, 8.8 or 9, and the time is 0.5h to 2h, for example, it can be 0.5h, 0.75h, 1h, 1.25h, 1.5h, 1.75h or 2h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0095] Preferably, the neutralization and precipitation of manganese in step (4) uses industrial liquid alkali with a concentration of 30wt% to 32wt% (e.g., 30wt%, 30.5wt%, 31wt%, 31.5wt%, or 32wt%) or 40wt% to 42wt% (e.g., 40wt%, 40.5wt%, 41wt%, 41.5wt%, or 42wt%) to adjust the pH.

[0096] Preferably, after the neutralization and precipitation of manganese in step (4) is completed, an eighth solid-liquid separation is performed to obtain the manganese hydroxide and the manganese precipitation mother liquor.

[0097] The main reaction equation for the neutralization and manganese precipitation treatment described in this invention is as follows:

[0098] Mn 2+ +2OH - =Mn(OH)2↓.

[0099] This invention converts manganese ions into manganese hydroxide precipitate by adding alkali. After the eighth solid-liquid separation process, manganese mother liquor and manganese hydroxide are obtained. The manganese hydroxide can be returned to the front-end battery recycling process for further manganese recovery.

[0100] Preferably, after the manganese precipitation mother liquor in step (4) and the aluminum precipitation mother liquor in step (3) are mixed, a third evaporation crystallization treatment is carried out to obtain distilled water and sodium chloride.

[0101] After the manganese precipitation mother liquor and the aluminum precipitation mother liquor of the present invention are mixed, a third evaporation and crystallization treatment is carried out to obtain distilled water and sodium chloride. The distilled water can be reused as production water, and the obtained sodium chloride can be sold as a by-product.

[0102] The apparatus used in the first, second, third, fourth, fifth, sixth, seventh, and eighth solid-liquid separation processes of this invention includes centrifugal filters and / or pressure filters. Furthermore, the solid residues obtained after each of these separation processes must be washed with production water or distilled water to improve the purity of the product and by-products. The wash water is then returned to the previous process or used in the next process along with the separated liquid phase, replacing the production water or distilled water.

[0103] Compared with the prior art, the present invention has the following beneficial effects:

[0104] (1) The method described in this invention realizes the resource utilization of iron and aluminum slag through microwave treatment, acid dissolution, acid leaching, neutralization precipitation, alkali dissolution and evaporation crystallization, which reduces the outsourced disposal cost of iron and aluminum slag in the lithium battery recycling process and reduces the occupation of land resources; in addition, while recovering iron, aluminum, phosphorus, sulfur and fluorine elements, this invention also recovers metal elements such as nickel, cobalt and manganese, which basically realizes the recovery of all elements of iron and aluminum slag;

[0105] (2) The method described in this invention utilizes the characteristic of ammonia forming soluble complexes with nickel and cobalt to achieve the separation of nickel and cobalt elements from other elements;

[0106] (3) The method described in this invention adopts the waste gas treatment process of "concentrated sulfuric acid + sodium hydroxide", which realizes the recovery and purification of sulfur and hydrogen fluoride, converting them into by-products and ensuring that the waste gas meets the emission standards.

[0107] (4) The method of the present invention realizes the recycling of distilled water and washing water, without generating wastewater, and achieves zero wastewater discharge. Attached Figure Description

[0108] Figure 1 This is a flowchart of the method described in Embodiment 1 of the present invention. Detailed Implementation

[0109] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0110] Example 1

[0111] This embodiment provides a method for the resource recovery of iron-aluminum slag, the flowchart of which is shown below. Figure 1 As shown, the method includes the following steps:

[0112] (1) The iron-aluminum slag is sent to an industrial microwave oven and microwaved at 550°C for 6 hours to obtain microwave treated material. Microwave treated material and acid solvent with a mass ratio of 1:6 are added to a reaction tank A with stirring. The acid solvent is prepared by mixing production water with 30wt% industrial hydrochloric acid. Stirring is turned on for acid dissolution for 3 hours. The pH of acid dissolution is 0.5. After acid dissolution, it is pumped to plate and frame filter press A for the first solid-liquid separation. After filtration, production water is introduced to wash the solid slag. The wash water is returned to the acid dissolution process to replace the production water to obtain an acid solution. The acid solution is transferred to a reaction tank B with stirring. Under nitrogen protection, 28wt% ammonia water is added to adjust the pH to 10.5 and neutralization precipitation reaction is carried out for 1 hour. After the reaction is completed, the solid-liquid mixture is sent to plate and frame filter press B for the second solid-liquid separation. After filtration, neutralization mother liquor and the first solid slag are obtained. Production water is introduced to wash the solid slag. The wash water is carried into the next process along with the neutralization mother liquor.

[0113] The first waste gas generated by the microwave treatment is treated by a three-stage absorption tower before being discharged in compliance with standards. Both the first and second stage absorption towers use 78wt% concentrated sulfuric acid as the first absorbent for the first waste gas treatment, while the third stage absorption tower uses 30wt% industrial liquid alkali as the second absorbent for the second waste gas treatment. The treated waste gas is then discharged in compliance with standards. During the operation of the first and second stage absorption towers, the concentration of the first absorbent is controlled within the range of 70% to 95%, while the third stage absorption tower controls the pH of the second absorbent to be ≥8.5. If the absorbent exceeds these ranges, it is replaced. The replaced sulfuric acid solution is sold as a byproduct, while the replaced second absorbent enters evaporation system A for first-stage evaporation and crystallization to obtain distilled water and sodium fluoride. The distilled water is reused as production water, and the sodium fluoride is sold as a byproduct.

[0114] (2) The neutralization mother liquor and washing water mentioned in step (1) are neutralized and treated with hydrochloric acid in a reaction tank E with stirring. The pH of the neutralization and nickel-cobalt treatment is controlled to be 9. The reaction is stirred for 1 hour. After the reaction is completed, the solid-liquid mixture is sent to a plate and frame filter press E for the third solid-liquid separation. Production water is introduced to wash the solid slag. The washing water enters the reaction tank F with stirring along with the nickel-cobalt mother liquor. The solid slag obtained by the plate and frame filter press E is a mixture of nickel phosphate and cobalt phosphate, which is sent to the battery recycling section for further recovery of nickel and cobalt.

[0115] Stirring is started in reaction tank F. Magnesium chloride is added to the nickel-cobalt precipitate mother liquor at 0.94 times the theoretical dosage according to the phosphate content. The ammonium phosphate precipitation reaction is carried out for 2 hours. After the reaction is completed, the solid-liquid mixture is sent to centrifuge A for the fourth solid-liquid separation treatment. The obtained solid crystal is magnesium ammonium phosphate, which is sold as a product. The resulting crystal mother liquor is adjusted to pH 6.5 with 30wt% industrial hydrochloric acid and then enters the evaporation crystallization system B for the second evaporation crystallization (temperature is 90℃) to obtain ammonium chloride and distilled water. Ammonium chloride is sold as a by-product and distilled water is reused as production water. When the concentration of diammonium phosphate in the evaporation mother liquor is close to saturation, it is returned to reaction tank F and treated together with the nickel-cobalt precipitate mother liquor for ammonium phosphate precipitation.

[0116] The first solid slag in step (1) is unloaded into a reaction tank C pre-filled with an alkaline leaching agent and equipped with a stirrer for alkaline leaching treatment. The alkaline leaching agent is prepared by mixing production water with 30 wt% industrial liquid alkali. Stirring is turned on, and the alkaline leaching agent is added according to the mass ratio of solid slag to alkaline leaching agent of 1:6. The pH of the alkaline leaching treatment is controlled at 13.3, and the alkaline leaching is carried out for 4 hours. After the alkaline leaching is completed, the solid-liquid mixture is sent to a plate and frame filter press C for the fifth solid-liquid separation. After the filter press is completed, production water is introduced to wash the solid slag. The wash water is returned to the alkaline leaching process to replace the production water, and the alkaline leaching liquid and the second solid slag are obtained.

[0117] (3) The alkaline leaching solution described in step (2) is neutralized and treated with 30wt% industrial hydrochloric acid in a reaction tank G with stirring, the pH is controlled at 7.5, and the reaction is stirred for 0.5h. After the reaction is completed, the solid-liquid mixture is sent to a plate and frame filter press F for the sixth solid-liquid separation. After the filter press is completed, production water is introduced to wash the solid residue. The wash water is returned to the reaction tank C to replace the production water. After the water washing is completed, the solid residue obtained by filtration is aluminum hydroxide, which is sold as a product. The aluminum precipitation mother liquor obtained by filtration is sent to the evaporation crystallization system C for treatment.

[0118] Step (2) The second solid residue is unloaded into a reaction tank D pre-filled with acid leaching agent and equipped with a stirrer for acid leaching treatment. Stirring is turned on, and acid leaching agent is added until the mass ratio of the second solid residue to the acid leaching agent is 1:6. The acid leaching agent is prepared by mixing production water with 30wt% industrial hydrochloric acid. The pH is controlled at 3.7 during the acid leaching process, and the reaction is carried out for 2 hours. After the acid leaching is completed, the solid-liquid mixture is sent to the plate and frame filter press D for the seventh solid-liquid separation. After the filter press is completed, production water is introduced to wash the solid residue. The wash water is returned to the acid leaching process to replace the production water. After the water washing is completed, the filter residue is sent to the dryer and dried at 200℃ for 3 hours to obtain ferric hydroxide.

[0119] (4) The acid leaching solution obtained in step (3) is neutralized and manganese is precipitated in a reaction tank H with stirring using 30wt% industrial liquid alkali. The pH is controlled at 8 and the reaction is stirred for 0.5h. After the reaction is completed, the solid-liquid mixture is sent to a plate and frame filter press G for the eighth solid-liquid separation. After the filter press is completed, production water is introduced to wash the solid slag. The wash water is returned to the reaction tank D to replace the production water. After the water washing is completed, the solid slag obtained by filtration is manganese hydroxide, which is sent to the battery recycling section for further manganese recovery. The manganese precipitating mother liquor obtained by filtration is sent to the evaporation crystallization system C to be treated with aluminum precipitating mother liquor for the third evaporation treatment to obtain sodium chloride and distilled water. Sodium chloride is sold as a by-product and distilled water is reused as production water.

[0120] Example 2

[0121] This embodiment provides a method for the resource recovery of iron and aluminum slag, the method comprising the following steps:

[0122] (1) The iron-aluminum slag is sent to an industrial microwave oven and microwaved at 700°C for 2 hours to obtain microwave treated material. Microwave treated material and acid solvent with a mass ratio of 1:10 are added to a reaction tank A with stirring. The acid solvent is prepared by distilled water and 15wt% industrial hydrochloric acid. Stirring is turned on for acid dissolution for 2 hours. The pH of acid dissolution is controlled at 1. After acid dissolution, it is pumped to plate and frame filter press A for the first solid-liquid separation. After filtration, distilled water is introduced to wash the solid slag. The wash water is returned to the acid dissolution process to replace the distilled water to obtain an acid solution. The acid solution is transferred to a reaction tank B with stirring. Under nitrogen protection, 20wt% ammonia water is added to adjust the pH to 11 and neutralization precipitation reaction is carried out for 2 hours. After the reaction is completed, the solid-liquid mixture is sent to plate and frame filter press B for the second solid-liquid separation. After filtration, neutralization mother liquor and the first solid slag are obtained. Distilled water is introduced to wash the solid slag. The wash water is carried to the next process along with the neutralization mother liquor.

[0123] The first waste gas generated by the microwave treatment is treated by a three-stage absorption tower before being discharged in compliance with standards. Both the first and second stage absorption towers use 90wt% concentrated sulfuric acid as the first absorbent for the first waste gas treatment, while the third stage absorption tower uses 32wt% industrial liquid alkali as the second absorbent for the second waste gas treatment. The treated waste gas is then discharged in compliance with standards. During the operation of the first and second stage absorption towers, the concentration of the first absorbent is controlled within the range of 70%–95%, while the third stage absorption tower controls the pH of the second absorbent to be ≥8.5. If the absorbent exceeds these ranges, it is replaced. The replaced sulfuric acid solution is sold as a byproduct, while the replaced second absorbent enters evaporation system A for first-stage evaporation and crystallization to obtain distilled water and sodium fluoride. The distilled water is reused as production water, and the sodium fluoride is sold as a byproduct.

[0124] (2) The neutralization mother liquor and washing water mentioned in step (1) are neutralized and treated with hydrochloric acid in a reaction tank E with stirring. The pH of the neutralization and nickel-cobalt treatment is controlled at 8. The reaction is stirred for 2 hours. After the reaction is completed, the solid-liquid mixture is sent to a plate and frame filter press E for the third solid-liquid separation. Distilled water is introduced to wash the solid residue. The washing water is introduced into the reaction tank F with stirring along with the nickel-cobalt mother liquor. The solid residue obtained by the plate and frame filter press E is a mixture of nickel phosphate and cobalt phosphate. It is sent to the battery recycling section for further recovery of nickel and cobalt.

[0125] Stirring is started in reaction tank F. Magnesium chloride is added to the nickel-cobalt precipitate mother liquor at 1 times the theoretical dosage according to the phosphate content. The ammonium phosphate precipitation reaction is carried out for 0.5 hours. After the reaction is completed, the solid-liquid mixture is sent to centrifuge A for the fourth solid-liquid separation treatment. The obtained solid crystal is magnesium ammonium phosphate, which is sold as a product. The resulting crystal mother liquor is adjusted to pH 5.5 with 15wt% industrial hydrochloric acid and then enters the evaporation crystallization system B for the second evaporation crystallization (temperature is 100℃) to obtain ammonium chloride and distilled water. Ammonium chloride is sold as a by-product, and distilled water is reused as production water. When the concentration of diammonium phosphate in the evaporation mother liquor is close to saturation, it is returned to reaction tank F and treated together with the nickel-cobalt precipitate mother liquor for ammonium phosphate precipitation.

[0126] The first solid residue from step (1) is unloaded into a reaction tank C pre-filled with an alkaline leaching agent and equipped with a stirrer for alkaline leaching treatment. The alkaline leaching agent is prepared by mixing distilled water with 30 wt% industrial liquid alkali. Stirring is turned on, and the alkaline leaching agent is added according to the mass ratio of solid residue to alkaline leaching agent of 1:8. The pH of the alkaline leaching treatment is controlled at 12.5, and the alkaline leaching is carried out for 2 hours. After the alkaline leaching is completed, the solid-liquid mixture is sent to a plate and frame filter press C for the fifth solid-liquid separation. After the filter press is completed, distilled water is introduced to wash the solid residue. The wash water is returned to the alkaline leaching process to replace the distilled water, and the alkaline leaching liquid and the second solid residue are obtained.

[0127] (3) The alkaline leaching solution described in step (2) is neutralized and treated with 15wt% industrial hydrochloric acid in a reaction tank G with stirring, the pH is controlled at 6, and the reaction is stirred for 2 hours. After the reaction is completed, the solid-liquid mixture is sent to a plate and frame filter press F for the sixth solid-liquid separation. After the filter press is completed, distilled water is introduced to wash the solid residue. The wash water is returned to the reaction tank C to replace the distilled water. After the water washing is completed, the solid residue obtained by filtration is aluminum hydroxide, which is sold as a product. The aluminum precipitation mother liquor obtained by filtration is sent to the evaporation crystallization system C for treatment.

[0128] Step (2) The second solid residue is unloaded into a reaction tank D pre-filled with acid leaching agent and equipped with a stirrer for acid leaching treatment. Stirring is turned on, and acid leaching agent is added until the mass ratio of the second solid residue to the acid leaching agent is 1:10. The acid leaching agent is prepared by distilled water and 15wt% industrial hydrochloric acid. The pH is controlled at 4.2 during the acid leaching process and the reaction is carried out for 4 hours. After the acid leaching is completed, the solid-liquid mixture is sent to the plate and frame filter press D for the seventh solid-liquid separation. After the filter press is completed, distilled water is introduced to wash the solid residue. The wash water is returned to the acid leaching process to replace the distilled water. After the water washing is completed, the filter residue is sent to the dryer and dried at 120℃ for 1 hour to obtain iron hydroxide.

[0129] (4) The acid leaching solution obtained in step (3) is neutralized and manganese is precipitated in a reaction tank H with stirring using 32wt% industrial liquid alkali. The pH is controlled at 9 and the reaction is stirred for 2 hours. After the reaction is completed, the solid-liquid mixture is sent to a plate and frame filter press G for the eighth solid-liquid separation. After the filter press is completed, distilled water is introduced to wash the solid residue. The wash water is returned to the reaction tank D to replace the distilled water. After the water washing is completed, the solid residue obtained by filtration is manganese hydroxide, which is sent to the battery recycling section for further manganese recovery. The manganese precipitating mother liquor obtained by filtration is sent to the evaporation crystallization system C to be treated with the aluminum precipitating mother liquor for the third evaporation treatment to obtain sodium chloride and distilled water. Sodium chloride is sold as a by-product and distilled water is reused as production water.

[0130] Comparative Example 1

[0131] This comparative example provides a method for the resource recovery of iron and aluminum slag, the method comprising the following steps:

[0132] Add 3 parts alkaline washing water and 1 part iron-aluminum slag to stirred mill A, and start stirring for 1 hour to make a slurry. After slurry making, transfer the slurry to reaction tank A and add industrial liquid alkali. Control the reaction temperature with steam at 60℃ and react for 4 hours, controlling the pH of the reaction process at 13. After the reaction is complete, pump the solid-liquid mixture to plate and frame filter press A for filtration. After filtration, unload the filter residue into stirred mill B pre-filled with production water, start stirring, and add production water until the solid-liquid ratio is 1g:3mL. Wash with water for 1 hour. After washing with water, send the solid-liquid mixture to plate and frame filter press B for filtration. After filtration, unload the filter residue into stirred mill C pre-filled with acidic washing water, start stirring, and add production water or acid washing water until the solid-liquid ratio is 1g:3mL. Add industrial hydrochloric acid with a concentration of 30wt%, and react for 4 hours, controlling the pH of the reaction process at 3.7. After the reaction is complete, the solid-liquid mixture is pumped to a plate and frame filter press C for filtration. After filtration, the filter residue is discharged into a stirred mill D pre-filled with production water. Stirring is started, and production water is added to bring the solid-liquid ratio to 1 g:3 mL. The mixture is then washed for 1 hour. After washing, the solid-liquid mixture is sent back to the plate and frame filter press D for filtration. After filtration, the filter residue is fed into a kiln and calcined at 550℃ for 3 hours to obtain iron oxide. In the above process, the alkaline wash water is returned to the alkaline leaching process to replace the production water, and the acidic wash water is returned to the acid leaching process to replace the production water.

[0133] The filtrate obtained from plate and frame filter press A is an alkaline leaching solution, which is transferred to reaction tank B equipped with a stirrer. Based on the F in the alkaline leaching solution... - SO4 2- PO4 3- The amount of Ca was calculated 2+ The theoretical addition amount was calculated, and then 1.25 times the theoretical addition amount of a purification agent, composed of calcium chloride and calcium hydroxide, was added. The reaction process was controlled at pH=13 and the reaction time was 0.5h. After the reaction was completed, the solid-liquid mixture was sent to plate and frame filter press E for filtration. After filtration, the filtrate was transferred to a reaction tank C with stirring, and industrial hydrochloric acid was added to adjust the pH to 8.5. The reaction was carried out for 1h. After the reaction was completed, the solid-liquid mixture was sent to plate and frame filter press H for filtration. After filtration, the filter residue was aluminum hydroxide, which was sold as a by-product.

[0134] The filtrate obtained from the plate and frame filter press C is an acid leaching solution, which is transferred to the reaction tank D with stirring. Industrial liquid alkali is added to adjust the pH to 8.5, and the reaction is carried out for 1 hour. After the reaction is completed, the solid-liquid mixture is sent to the plate and frame filter press F for filtration. After filtration, the filter residue is mainly composed of nickel, cobalt and manganese hydroxides, which are returned to the battery recycling process for further processing to recover and utilize precious metal elements such as nickel, cobalt and manganese.

[0135] In the methods described in the above embodiments and comparative examples, the recovery rates of iron, aluminum, phosphorus, sulfur, fluorine, nickel, cobalt, and manganese are calculated as follows: element recovery rate = element content in the recovered target material / element content in the input iron and aluminum slag × 100%. As shown in Table 1, since nickel, cobalt, and manganese were recovered simultaneously in Comparative Example 1, Table 1 shows the total recovery rate of nickel, cobalt, and manganese.

[0136] Table 1

[0137]

[0138]

[0139] As shown in Table 1, the present invention can recover iron, aluminum, phosphorus, sulfur, fluorine, nickel, cobalt and manganese elements, and the recovery rate is relatively high.

[0140] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for the resource recovery of iron and aluminum slag, characterized in that, The method includes the following steps: (1) After microwave treatment of iron-aluminum slag, acid dissolution is performed to obtain an acid solution. The acid solution is then subjected to a neutralization and precipitation reaction to obtain a neutralization mother liquor and a first solid phase slag. The first waste gas generated by the microwave treatment is treated to obtain sulfuric acid solution and fluoride. (2) The neutralization mother liquor in step (1) is subjected to neutralization and nickel-cobalt precipitation treatment to obtain nickel-cobalt precipitate and nickel-cobalt precipitation mother liquor. The nickel-cobalt precipitation mother liquor is subjected to ammonium phosphate precipitation treatment to obtain crystallization mother liquor and ammonium phosphate compound. The first solid residue from step (1) is subjected to alkaline leaching to obtain an alkaline leaching solution and a second solid residue. (3) Neutralize the alkaline leaching solution described in step (2) to obtain aluminum hydroxide and aluminum precipitation mother liquor; The second solid residue from step (2) is subjected to acid leaching to obtain an acid leaching solution and a third solid residue. (4) After drying the third solid slag described in step (3), ferric hydroxide is obtained; The acid leaching solution described in step (3) is neutralized and manganese is precipitated to obtain manganese hydroxide and manganese precipitate mother liquor, thus completing the recovery of iron, aluminum, phosphorus, sulfur, fluorine, nickel, cobalt and manganese elements from the iron-aluminum slag.

2. The method according to claim 1, characterized in that, The microwave treatment in step (1) is performed at a temperature of 500℃ to 700℃ for 2 hours to 6 hours. Preferably, the acid solvent used in step (1) includes a first aqueous solvent and a first acid solution; Preferably, the mass ratio of the microwave-treated iron-aluminum slag obtained by microwave treatment of iron-aluminum slag in step (1) to the acid solvent is 1:(5-10); Preferably, the first acid solution comprises industrial hydrochloric acid with a concentration of 15wt% to 30wt%; Preferably, the pH of the acid dissolution in step (1) is 0.5 to 1, and the time is 2 to 4 hours; Preferably, after the acid dissolution in step (1) is completed, a first solid-liquid separation is performed to obtain the acid solution.

3. The method according to claim 1 or 2, characterized in that, In step (1), the acid solution is subjected to a neutralization and precipitation reaction using ammonia-based substances under a protective atmosphere. Preferably, the ammonia-like substances include ammonia water and / or ammonia gas; Preferably, the protective atmosphere includes nitrogen; Preferably, the pH of the neutralization precipitation reaction in step (2) is 10.5 to 11, and the time is 0.5 h to 2 h; Preferably, after the neutralization and precipitation reaction in step (1) is completed, a second solid-liquid separation is performed to obtain the neutralization mother liquor and the first solid residue.

4. The method according to any one of claims 1-3, characterized in that, The waste gas treatment in step (1) includes passing the first waste gas generated by microwave treatment into the first absorbent liquid, the first absorbent liquid including concentrated sulfuric acid solution, to obtain the sulfuric acid solution and the second waste gas in step (1). The second waste gas is passed into the second absorbent liquid for absorption to obtain an alkaline absorbent liquid, the second absorbent liquid including alkaline solution. The alkaline absorbent liquid is subjected to a first evaporation crystallization treatment to obtain distilled water and fluoride. Preferably, the first absorbent comprises a concentrated sulfuric acid solution with a concentration of 70 wt% to 95 wt%; Preferably, the second absorbent comprises industrial liquid alkali with a concentration of 30wt% to 32wt% or industrial liquid alkali with a concentration of 40wt% to 42wt%. Preferably, when the pH of the alkali absorption solution is < 8.5, the alkali absorption solution is subjected to a first evaporation and crystallization treatment to obtain distilled water and sodium fluoride.

5. The method according to any one of claims 1-3, characterized in that, Add hydrochloric acid to perform the neutralization and nickel-cobalt precipitation treatment described in step (2); Preferably, the pH of the neutralization treatment of nickel and cobalt in step (2) is 8 to 9, and the time is 0.5 h to 2 h; Preferably, after the neutralization and nickel-cobalt precipitation treatment in step (2) is completed, a third solid-liquid separation is performed to obtain the nickel-cobalt precipitate and the nickel-cobalt precipitate mother liquor.

6. The method according to any one of claims 1-4, characterized in that, Magnesium chloride is added to perform the ammonium phosphate precipitation treatment described in step (2); Preferably, the amount of magnesium chloride added is 0.9 to 1 times the theoretical amount required to convert all phosphate ions into magnesium ammonium phosphate; Preferably, the ammonium phosphate precipitation treatment time in step (2) is 0.5h to 2h; Preferably, after the ammonium phosphate precipitation treatment in step (2) is completed, a fourth solid-liquid separation is performed to obtain crystallization mother liquor and magnesium ammonium phosphate; Preferably, the mother liquor from step (2) undergoes a second evaporation crystallization treatment to obtain ammonium chloride; Preferably, before the second evaporation crystallization treatment, the mother liquor in step (2) is first adjusted to pH 5.5 to 6.5 using industrial hydrochloric acid with a concentration of 15wt% to 30wt%; Preferably, the temperature of the second evaporation crystallization treatment is ≤100℃.

7. The method according to any one of claims 1-6, characterized in that, The alkaline leaching agent used in step (2) includes a second aqueous solvent and liquid alkali; Preferably, in step (2), the mass ratio of the first solid residue to the alkaline leaching agent is 1:(5-8); Preferably, the pH of the alkaline leaching treatment in step (2) is 12.5 to 13.5, and the time is 2 to 5 hours. Preferably, after the alkaline leaching treatment in step (2) is completed, a fifth solid-liquid separation is performed to obtain the alkaline leaching solution and the second solid residue.

8. The method according to any one of claims 1-6, characterized in that, The pH of the neutralization and aluminum precipitation treatment in step (3) is 6-8, and the time is 0.5h-2h; Preferably, the neutralization and aluminum precipitation treatment in step (3) uses industrial hydrochloric acid with a concentration of 15wt% to 30wt% to adjust the pH; Preferably, after the neutralization and aluminum precipitation treatment in step (3) is completed, a sixth solid-liquid separation is performed to obtain the aluminum hydroxide and the aluminum precipitation mother liquor.

9. The method according to any one of claims 1-8, characterized in that, The acid leaching agent used in step (3) includes a third aqueous solvent and a second acid solution; Preferably, in step (3), the mass ratio of the second solid residue to the acid leaching agent is 1:(5-10); Preferably, the second acid solution comprises industrial hydrochloric acid with a concentration of 15wt% to 30wt%; Preferably, the pH of the acid leaching treatment in step (3) is 3.5 to 4.2, and the time is 2 to 4 hours; Preferably, after the acid leaching treatment in step (3) is completed, a seventh solid-liquid separation is performed to obtain the acid leaching solution and the third solid residue.

10. The method according to any one of claims 1-7, characterized in that, The drying temperature of the third solid slag in step (3) is 120℃~200℃, and the time is 1h~4h; Preferably, the pH of the neutralization and manganese precipitation treatment in step (4) is 8-9, and the time is 0.5h-2h; Preferably, the neutralization and precipitation of manganese in step (4) uses industrial liquid alkali with a concentration of 30wt% to 32wt% or 40wt% to 42wt% to adjust the pH. Preferably, after the neutralization and precipitation of manganese in step (4) is completed, an eighth solid-liquid separation is performed to obtain the manganese hydroxide and the manganese precipitation mother liquor; Preferably, after the manganese precipitation mother liquor in step (4) and the aluminum precipitation mother liquor in step (3) are mixed, a third evaporation crystallization treatment is carried out to obtain distilled water and sodium chloride.

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