Process for recycling components from alkaline batteries

Abstract

This invention involves the separation and recovery of metals from ground alkaline batteries using anode slime (zinc electrolysis waste) and other materials containing manganese and zinc. The material, commonly known as alkaline black (AKB), is dissolved in a sulfate medium and the manganese to zinc ratio is adjusted. The metal-containing solution is treated using crystallization and ion exchange methods to produce manganese sulfate and zinc sulfate solutions for a variety of possible applications.

Description

Technical Field

[0001] The present invention relates to a method for separating and recovering metals from ground alkaline batteries using anode slime (zinc electrolysis waste) and other materials containing manganese and zinc. The material, commonly known as alkaline black (AKB), is dissolved in a sulfate medium and the manganese to zinc ratio is adjusted. The metal-containing solution is then treated using crystallization and ion exchange methods to produce manganese sulfate and zinc sulfate solutions for a variety of possible applications. Background Art

[0002] The electrification of transport is increasing the demand for electricity storage in terms of volume and capacity. Electricity, for example, used in electric vehicles, is stored in lithium-ion batteries, which typically contain lithium, manganese, nickel, and cobalt. These metals currently come from primary sources, i.e., mining, a process that is energy-intensive and depletes natural resources. As the demand for battery metals increases, the importance of secondary sources of these elements is growing. Effectively utilizing secondary metal sources allows for the cost-effective production of battery metal salts while conserving natural resources. For manganese, several secondary sources are available.

[0003] A large secondary source of manganese comes from the recycling process of zinc-manganese dioxide batteries (i.e., alkaline batteries). "Black lumps" from alkaline batteries (alkaline black, AKB) are produced by crushing the batteries and screening the resulting material to separate the shell and organic matter from the positive and negative electrode materials. Currently, metals are recovered from black lumps by pyrometallurgical routes (smelting) or by combining heat treatment with hydrometallurgy. The hydrometallurgical route typically involves selective solvent extraction and precipitation. According to international patent application WO2013124399A1, alkaline black is first washed with water to separate potassium as a hydroxide solution. The alkaline black is then reduced with hydrogen, followed by an ammonia leaching step that selectively leaches zinc from the material. The ammonia is evaporated, and the zinc is recovered as a hydroxide filter cake. The zinc-poor alkaline black is then subjected to reduction leaching with sulfuric acid and citric acid, which dissolves the manganese as manganese sulfate, which is then separated by filtration. The filtrate is then mixed with sodium carbonate to precipitate manganese as manganese carbonate, which is separated from the sodium sulfate wastewater by filtration.

[0004] During the final stage of the zinc refining process, electrolysis, impurities are deposited as solid waste near the anodes. This mass is called anode slime (AM), and it is often removed from the process. The main components of anode slime are manganese, lead, zinc, and smaller amounts of other elements such as iron and calcium. Anode slime is classified as a hazardous material and needs to be landfilled safely. Current routes of use are generally based on pyrometallurgy. In the hydrometallurgical route, metals can be recovered from anode slime by dissolving it with sulfuric acid, separating the lead sulfate and other major impurities as a solid residue, and further hydrometallurgical steps to purify the dissolved manganese sulfate.

[0005] In a study published in the Journal of Cleaner Production in 2019, S. Lannoo et al. described a process in which ion exchange resins were used to separate trace amounts of zinc from a highly concentrated manganese solution obtained from a solvent exchange process.

[0006] FI127830 discloses a method for pretreating alkaline black slugs from spent alkaline batteries. The pretreated alkaline black slugs are subject to a leaching process for recovering one or more metals from the pretreated alkaline black slugs. The invention also relates to a method, apparatus, and system for treating spent alkaline battery black slugs. In this process, alkaline black is first calcined to remove graphite and organic matter, and the resulting material is then leached with sulfuric and citric acids. Impurities are filtered out, and the resulting manganese sulfate and zinc sulfate solution containing citric acid is used as a fertilizer or the zinc is separated as hydroxide by precipitation and filtration.

[0007] In the process according to the present invention, the expensive solvent exchange step is avoided by directly dissolving AKB with sulfuric acid to obtain a filtrate rich in manganese and zinc. The calcination process is also avoided, which results in a lower CO2 shock and a lower potential for graphite reuse. By using ion exchange as the separation method for manganese and zinc, the filtration step is also avoided. Other manganese-containing materials, such as anode mud, are used to adjust the manganese-zinc ratio so that the final ratio favors manganese. These liquids are then subjected to a thermal crystallization and ion exchange process to separate manganese and zinc by capturing zinc with a chelated ion exchange resin, leaving a purified manganese sulfate solution. The raffinate containing manganese sulfate is then discharged from the chromatography column, and zinc can be eluted from the resin. Furthermore, it has been found that pre-treating the ion exchange resin with a hydroxide solution enhances zinc binding. Summary of the Invention

[0008] The method for recovering metals from ground alkaline batteries according to the present invention comprises the following steps: (a) selectively leaching manganese and zinc from alkaline black under reducing conditions by mixing alkaline black and a material containing manganese oxide and / or manganese sulfate with a sulfuric acid solution at a leaching temperature of 15-40° C. for 1-5 hours to obtain a mixture; (b) filtering the mixture to obtain a filtrate of manganese sulfate and zinc sulfate and Pb / Ca / organic matter as a filter cake; (c) heating the manganese sulfate and zinc sulfate filtrate to a crystallization temperature of 70-100° C. and maintaining the crystallization temperature under reflux cooling for at least 30 minutes to precipitate manganese in the form of sulfate crystals; (d) filtering the sulfate crystals to obtain a manganese-depleted filtrate, and finally; (e) dissolving the sulfate crystals in water to obtain a sulfate solution, and separating manganese and zinc by chelate ion exchange.

[0009] Reducing conditions in the selective leaching step (step a) can be obtained by adding a reducing agent (such as hydrogen peroxide or sulfur dioxide) during mixing until the manganese and zinc are dissolved.

[0010] According to one embodiment, the material containing manganese oxide is manganese dioxide (MnO2), such as anode mud. In another embodiment, the material containing manganese oxide is manganese trioxide.

[0011] According to an embodiment of the recovery method of the present invention, the manganese sulfate and zinc sulfate filtrate obtained in the filtration step (step b) has a manganese to zinc ratio (Mn:Zn ratio) between 10:1 and 3.6:1.

[0012] In another embodiment, the manganese sulfate and zinc sulfate filtrate obtained in the filtering step (step b) has a manganese to zinc ratio (Mn:Zn ratio) between 7:1 and 5:1.

[0013] According to the present invention, manganese sulfate can be added at a stage prior to chelate ion exchange to adjust the manganese-zinc ratio.

[0014] If the feed manganese material contains impurities that precipitate at neutral pH, the pH of the mixture to be filtered in the filtration step (step b) is adjusted to between 1.5 and 7. The pH can be adjusted upwards with a hydroxide solution such as NH4OH, NaOH or KOH, or downwards with sulfuric acid prior to the above-mentioned filtration step (step b).

[0015] According to another embodiment, the pH adjustment can be performed at any stage before the chelate ion exchange in step (e). Thus, before entering the ion exchange stage, the sulfate solution from which manganese and zinc are separated by chelate ion exchange has a pH between 1.5 and 7. The pH can be adjusted upward with a hydroxide solution such as NH4OH, NaOH or KOH, or downward with sulfuric acid.

[0016] The basic black may be washed prior to the selective leaching step (step a) by mixing the basic black with water at a temperature between 5° C. and 100° C. for at least 30 minutes. According to one embodiment, the basic black is mixed with water at a temperature between 20° C. and 25° C. In one embodiment, the basic black is washed by mixing it with water for 1-2 hours.

[0017] In the recovery process according to the present invention, the manganese-depleted filtrate obtained from the filtration of the sulfate crystals (step d) can be returned to the leaching step (step a).

[0018] According to one embodiment of the present invention, in the chelate ion exchange step, a sulfate form of BPA resin is used. The BPA resin can be pretreated with ammonium hydroxide, sodium hydroxide or potassium hydroxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic flow chart of a method for recovering components from alkaline batteries according to the present invention.

[0020] Figure 2 is a schematic flow diagram of an ion exchange cycle according to the present invention.

[0021] definition

[0022] AKB refers to alkaline black, which is crushed alkaline batteries.

[0023] AM refers to anode slime produced as waste in zinc electrolysis.

[0024] BPA is dimethylpyridylamine, which is used, for example, as an ion exchange resin.

[0025] DC refers to dry content.

[0026] ICP-MS refers to inductively coupled plasma mass spectrometry.

[0027] An IEX cycle refers to the complete ion exchange process, including pretreatment, loading, elution, and regeneration.

[0028] Contains Mn x O y The material, ie, the material containing manganese oxide, may be, for example, anode slime or manganese trioxide.

[0029] MP-AES refers to microwave plasma atomic emission spectrometry.

[0030] Room temperature (RT) refers to temperature, which ranges from 20°C to 25°C. DETAILED DESCRIPTION

[0031] Typically, basic black (AKB) is expected to contain 20-40 wt% graphite and organic matter, which are burned off when calcined at temperatures above 600°C. Calcinated AKB is expected to contain 30-45 wt% zinc oxide, 25-30 wt% manganese oxide, and 7-12 wt% potassium hydroxide. It also contains less than 1 wt% of other impurities, such as iron, calcium, and magnesium, also in the form of oxides. The remainder can be assumed to be oxygen in the form of metal oxides, and moisture. Alkaline mud (AM) contains manganese, zinc, and lead in the form of oxides, and calcium in the form of sulfates. AM is expected to contain 25-40 wt% water. In dry form, AM is expected to contain 30-40 wt% manganese, 3-6 wt% lead, 2-4 wt% calcium, and 0.5-1 wt% zinc in the form of oxides. It also contains less than 0.2 wt% of other elements, such as iron and magnesium. The remainder can be assumed to be oxygen in the form of oxides and moisture.

[0032] Now refer to Figure 1 and 2 The schematic flow chart describes the process in detail.

[0033] According to the present invention, the basic black can be washed with water (AKB washing) as an optional pretreatment step in the recovery process. Washing is complete if the manganese sulfate obtained as the final product in this process does not contain potassium. In this optional washing step, potassium hydroxide (KOH) is dissolved from the basic black by mixing the AKB with water at a temperature between 5°C and 100°C (preferably between 20°C and 25°C) for at least 30 minutes (preferably 1-2 hours). The washed AKB is then separated from the washing liquid by filtration, and the washing liquid (potassium hydroxide solution) can be reused to wash another batch of AKB. Depending on the end use of the potassium hydroxide solution (e.g., crystallization), the washing liquid can be recycled to the next batch to increase the KOH concentration.

[0034] The AKB wash step is optional, as can basic black be used.

[0035] In the first step (step a) of the recovery method according to the present invention, manganese and zinc are selectively leached (reduction leaching) from AKB by: reacting AKB with a material containing manganese oxide (containing Mn) with a sulfuric acid solution; x O y The mixture is mixed with anode mud and manganese trioxide (Mn2O3) and / or manganese sulfate. The manganese concentration of the resulting filtrate is 100-180 g / l, preferably 140-150 g / l, and the zinc concentration is 10-50 g / l, preferably 20-30 g / l. The density of the filtrate is 1.38-1.47 g / l, preferably 1.4-1.45 g / l. Therefore, the manganese-zinc ratio (Mn:Zn ratio) is 10:1-3.6:1, preferably 7:1-5:1. A reducing agent (such as hydrogen peroxide or sulfur dioxide) is added during mixing until the manganese and zinc dissolve. This can be determined by measuring the redox potential of the solution. During mixing, the mixture is maintained at 15-40°C, preferably 20-30°C, and mixing is continued for 1-5 hours, preferably 2-3 hours.

[0036] Then, in the second step (step b), the mixture is filtered to obtain a manganese sulfate and zinc sulfate solution with a pH of 1.5-7 (preferably 2-6) as a filtrate (manganese sulfate / zinc sulfate filtrate) and a Pb / Ca / organic matter filter cake. The Pb / Ca / organic matter filter cake can be used as a raw material in graphite production or used in lead smelting to recover lead.

[0037] If the pH is not in the correct range, it can be optionally adjusted upward with a hydroxide solution (e.g., NH4OH, NaOH, or KOH) or downward with sulfuric acid. pH adjustment is performed to ensure that the pH is correct for ion exchange and to precipitate impurities present in the feed. pH adjustment can be performed at any step prior to ion exchange. In an embodiment, pH adjustment can be performed before filtering the Pb / Ca / organic residue, i.e., before step (b). This can be advantageous when the feed manganese material contains impurities that precipitate at neutral pH.

[0038] In the subsequent step (step c) of the recovery process according to the present invention, the manganese sulfate and zinc sulfate filtrate is heated in a process called thermal crystallization and washing, which precipitates manganese in the form of sulfate crystals (crude MnSO4·H2O crystals). During this step, the mixture is heated to 70-100°C, preferably 80-100°C, and maintained at the desired temperature under reflux cooling for at least 30 minutes, preferably 1-2 hours, to avoid water evaporation, which could cause impurities to precipitate in the crystals.

[0039] The crystals are then separated from the process liquor by filtration (step d) to obtain crude MnSO4.H2O crystals as filter cake and a manganese-depleted solution as filtrate, which can be recycled to the reduction leaching step.

[0040] In the following step (step e) of the recovery process according to the invention, MnSO4.H2O crystals are dissolved in water to the desired manganese concentration, preferably 80-100 g / l. Zinc is then separated from the manganese sulfate solution by chelate ion exchange (see Figure 2 First, dimethylpyridylamine (BPA resin; sulfate form) is pretreated with ammonium hydroxide, sodium hydroxide, or potassium hydroxide (hydroxide solution). The ammonium sulfate, sodium sulfate, or potassium sulfate solution (sulfate solution) is then received as the product, and the resin is converted to the free amine form (BPA resin; free amine form). Manganese sulfate containing zinc (manganese sulfate / zinc sulfate solution) is then passed through the resin (BPA resin; loaded with Zn). The manganese sulfate raffinate is received as the product. Zinc is eluted from the resin (BPA resin; sulfate form) using a 10-30 wt% (preferably 15-25 wt%) sulfuric acid solution (sulfuric acid elution), and the zinc sulfate eluate is received as the product. After zinc elution, the resin is ready for another cycle, starting with the pretreatment.

[0041] According to one embodiment of the present invention, in the leaching step, ie the first step of the recovery process, other manganese dioxide is used instead of anode slime.

[0042] In another embodiment of the present invention, manganese sulfate is added in any step prior to ion exchange to increase the concentration of manganese sulfate in the process liquid.

[0043] Next, the present invention will be described with reference to the following examples, which are not intended to limit the scope of the present invention.

[0044] Example

[0045] Table 1 presents the metal compositions of basic black, anode slime, manganese oxide, and manganese sulfate used in the disclosed examples.

[0046] 150.76 g of basic black was slurried in 100 ml of water and stirred at room temperature for 1.5 hours. After leaching, the solid was separated from the liquid by filtration. The washings were analyzed by MP-AES (microwave plasma atomic emission spectrometry, Agilent Technologies) and are presented in Table 2. This washing can be recycled to the next batch to increase the KOH concentration.

[0047] Table 1. Metal compositions of AKB (before and after washing), anode mud (AM), manganese trioxide (Mn2O3) and manganese sulfate (MnSO4·H2O) analyzed by MP-AES. The values are given in mg / kg.

[0048] element AKB AKB, washed AM <![CDATA[Mn2O3]]> <![CDATA[MnSO4·H2O]]> Ca <5000 <5000 20 996 <5000 1 837 K 38 800 8 940 4 669 <5000 620 Mn 311 300 328 600 214 020 652 000 320 000 Pb <200 <200 28 188 <200 <200 Zn 174 100 150 700 6 032 <5000 <500

[0049] Table 2. Composition of AKB washing solution

[0050] element mg / l K 21 500 Mn <5 Pb 23 Zn <250

[0051] Example 1

[0052] 51.79 g of AM and 18.85 g of washed and dried AKB were mixed with 50 ml of water and 40 ml of 95 wt% sulfuric acid. 30 ml of 30 wt% H₂O₂ were gradually added over 2 hours, and the mixture was then dissolved at room temperature for half an hour. The mixture was filtered, and 130 ml of filtrate and 9.9 g of residue were recovered and analyzed by MP-AES. Since lead is difficult to measure by MP-AES due to signal overlap in the presence of large amounts of manganese, ICP-MS was used to ensure that lead was not dissolved in the leachate. In subsequent experiments, it was assumed that lead was not dissolved during this step. The results are presented in Tables 3a and 3b.

[0053] Table 3a. Composition of manganese sulfate / zinc sulfate filtrate

[0054] element mg / l Ca <500 K 3 090 Mn 97 100 Pb <30 Zn 22 900

[0055] Table 3b. Composition of the residue (i.e., Pb / Ca / organic filter cake)

[0056] element mg / kg Ca 32 100 K 612 Mn 8 480 Pb 43 400 Zn 4 040

[0057] 120 ml of the filtrate from the previous step was heated to a boil with constant mixing and reflux cooling. After boiling for 1 hour, the mixture was filtered. The resulting crystals were dried at room temperature and analyzed by MP-AES. The results are presented in Table 4.

[0058] Table 4. Composition of manganese sulfate crystals

[0059] element mg / kg Ca <5 000 K <500 Mn 235 000 Zn 19 100

[0060] 13 g of manganese sulfate crystals were dissolved in 40 ml of water and the pH was raised to 2.5 with 24 wt% NH₄OH. 10 ml of Lanxess MonoPlus TP220 (dimethylpyridinium amine functional group) was washed with 20 ml of 24 wt% NH₄OH and 20 ml of water. The manganese sulfate solution was passed through the resin. Zinc was extracted from the resin using 20 ml of 20 wt% H₂SO₄. The sample was analyzed by MP-AES, and the results are presented in Table 5.

[0061] Table 5. Composition of dissolved manganese sulfate solution, raffinate and eluate

[0062] element liquid Raffinate eluent Ca <500 <500 <60 K 1 040 530 <60 Mn 39 710 27 320 30 Zn 4 900 <50 6 150

[0063] Example 2

[0064] 23.02 g of washed AKB (DC 88.62%) and 13.03 g of manganese trioxide (Mn2O3) were slurried in 55 ml of water and 20 ml of 95 wt% H2SO4. Without additional heating, 30 wt% H2O2 was gradually added over 3.5 hours. The pH of the mixture was adjusted from 4.74 to 5.50 using a slurry of 2.11 g of Ca(OH)2 in water, after which the mixture was filtered. 90 ml of filtrate was recovered and analyzed by MP-AES. The results are presented in Table 6.

[0065] Table 6. Filtrate composition from leaching of AKB and manganese oxide after pH adjustment

[0066] element mg / l Ca <500 K 2 990 Mn 123 000 Zn 29 100

[0067] The filtrate from the previous step was heated to boiling point. After the mixture began to form crystals, the reaction was continued under reflux cooling for 1 hour. By filtering using a hot filter apparatus, 15.24 g of crystals (DC 83.75%) were recovered. The sample was analyzed by MP-AES and the results are presented in Table 7.

[0068] Table 7. Composition of dried manganese sulfate crystals from crystallization

[0069] element mg / l Ca <5 000 K 1 640 Mn 290 000 Zn 27 000

[0070] The crystals from the previous step were dissolved in 50 ml of water to form a 52 ml liquid with a pH of 6.46. Prior to ion exchange, the resin was pretreated with 40 ml of 10 wt% NH₄OH. The solution was circulated through 30 ml of dimethylpyridinium ion exchange resin for 4 hours. After ion exchange, 60 ml of raffinate was collected from the column. Zinc was extracted from the resin using 40 ml of 20 wt% H₂SO₄. The sample was analyzed by MP-AES, and the results are presented in Table 8.

[0071] Table 8. Composition of dissolved manganese sulfate crystals, raffinate, and eluate

[0072] element liquid Raffinate eluent Ca <500 <500 <500 K 392 210 <50 Mn 48 900 31 000 445 Zn 3 490 <50 3 600

[0073] Example 3

[0074] 22.72 g of washed AKB (DC 93.56%) and 13.31 g of manganese trioxide (Mn2O3) were slurried in 55 ml of water and 20 ml of 95 wt% H2SO4. 25 ml of 30 wt% H2O2 were gradually added over three hours. After reduction leaching, the pH of the mixture was 2.27. Residual solids were removed from 92 ml of the solution by filtration. The sample was analyzed by MP-AES, and the results are presented in Table 9.

[0075] Table 9. Composition of AKB and manganese oxide leaching

[0076] element mg / l Ca <500 K 3 100 Mn 126 000 Zn 28 200

[0077] The filtrate from the previous step was heated to boiling point, and excess water was removed by evaporation. After the mixture began to form crystals, the reaction was continued under reflux cooling for 1 hour. 29.97 g of crystals (DC 75.90%) were removed from 30 ml of the mother liquor by filtration using a hot filtration apparatus. A sample was analyzed by MP-AES, and the results are presented in Table 10.

[0078] Table 10. Composition of dried manganese sulfate crystals from crystallization

[0079] element mg / l Ca <5 000 K 2 730 Mn 284 000 Zn 45 600

[0080] The crystals from the previous step were dissolved in 40 ml of water to form a 45 ml liquid with a pH of 3.28. Prior to ion exchange, the resin was treated with 40 ml of 10 wt% NH₄OH. The solution was circulated through a 30 ml Lanxess MonoPlus TP220 for four hours. After ion exchange, 52 ml of raffinate was collected from the column. Zinc was extracted from the resin using 40 ml of 20 wt% H₂SO₄, and a series of eluate samples were collected, with volumes of 17 ml, 38 ml, 40 ml, and 23 ml, respectively. The samples were analyzed by MP-AES, and the results are presented in Table 11.

[0081] Table 11. Composition of dissolved manganese sulfate solution, raffinate and eluate

[0082] element liquid Raffinate Eluent 1 Eluent 2 Eluent 3 Eluent 4 Ca <500 <500 <500 <500 <500 <500 K 655 469 <50 <50 <50 <50 Mn 72 400 49 000 25 68 14 <5 Zn 10 300 <50 3 570 8 350 1 540 <250

[0083] Example 4

[0084] 23.01 g of washed AKB (DC 88.62%) and 30.03 g of technical manganese sulfate hydrate were slurried in 80 ml of water and 10 ml of 95 wt% H₂SO₄. 12 ml of 30 wt% H₂O₂ were gradually added over one hour. After reduction leaching, the pH of the mixture was adjusted from 2.61 to 5.58 using a slurry of 2.18 g of Ca(OH)₂ in water. Residual solids were removed from 100 ml of the solution by filtration. The sample was analyzed by MP-AES, and the results are presented in Table 12.

[0085] Table 12. Leachate composition from AKB leaching in the presence of technical grade manganese sulfate

[0086] element mg / l Ca <500 K 2 810 Mn 120 000 Zn 26 100

[0087] The filtrate from the previous step was heated to boiling point, and after the mixture began to form crystals, the reaction was continued under reflux cooling for 1 hour. 19.09 g of crystals (DC 81.88%) were removed from 49 ml of the mother liquor by filtration using a hot filter apparatus. The sample was analyzed by MP-AES, and the results are presented in Table 13.

[0088] Table 13. Composition of dried manganese sulfate crystals from crystallization

[0089]

[0090]

[0091] The crystals from the previous step were dissolved in 50 ml of water to form a solution with a pH of 6.30 and a volume of 55 ml. The solution was then circulated through a 30 ml Lanxess MonoPlus TP220 for four hours. Prior to ion exchange, the resin was pretreated with 40 ml of 10 wt% NH₄OH. After ion exchange, 63 ml of raffinate was collected from the column. Zinc was extracted from the resin using 40 ml of 20 wt% H₂SO₄, and a series of eluate samples were collected, with volumes of 16 ml, 40 ml, 40 ml, and 45 ml, respectively. The samples were analyzed by MP-AES, and the results are presented in Table 14.

[0092] Table 14. Composition of dissolved manganese sulfate solution, raffinate and eluate

[0093] element liquid Raffinate Eluent 1 Eluent 2 Eluent 3 Eluent 4 Ca <500 <500 <500 <500 <500 <500 K 517 360 <50 <50 <50 <50 Mn 60 700 42 600 14 144 42 5 Zn 4 160 <50 <250 3 970 1 130 <250

[0094] Example 5

[0095] 22.05 g of washed AKB (DC 93.56%) was slurried in 80 ml of water and 10 ml of 95 wt% H2SO4. 12 ml of 30 wt% H2O2 was gradually added over two hours. After reduction leaching, the pH was adjusted from 5.65 to 6.59 using a slurry of 4.35 g of Ca(OH)2 in water. Residual solids were removed from 90 ml of the solution by filtration. 30.89 g of industrial manganese sulfate hydrate was added to the filtrate to obtain a 100 ml volume of solution. The resulting solution was heated to boiling. After the mixture began to form crystals, the reaction was continued under reflux cooling for 1 hour. 19.97 g of crystals (DC 83.89%) were removed from 37 ml of the mother liquor by filtration using a hot filter apparatus. The sample was analyzed by MP-AES, and the results are presented in Table 15.

[0096] Table 15. Composition of the leachate before addition of manganese sulfate and the dried manganese sulfate crystals from crystallization

[0097] element leachate crystals Ca 692 <5000 K 620 1 560 Mn 35 800 326 000 Zn 3 880 4960

[0098] The crystals from the previous step were dissolved in 40 ml of water to form a solution with a pH of 7.01 and a volume of 40 ml. The solution was then circulated through a 30 ml Lanxess MonoPlus TP220 for four hours. Prior to ion exchange, the resin was pretreated with 40 ml of 10 wt% NH₄OH. After ion exchange, 52 ml of raffinate was collected from the column. Zinc was extracted from the resin using 40 ml of 20 wt% H₂SO₄, and a series of eluate samples were collected, with volumes of 17 ml, 40 ml, 45 ml, and 20 ml, respectively. The samples were analyzed by MP-AES, and the results are presented in Table 16.

[0099] Table 16. Composition of dissolved manganese sulfate solution, raffinate and eluate

[0100] element liquid Raffinate Eluent 1 Eluent 2 Eluent 3 Eluent 4 Ca <500 <500 <500 <500 <500 <500 K 606 330 <50 <50 <50 <50 Mn 92 000 49 500 <50 100 <50 <50 Zn 1 140 <50 <250 900 365 <250

[0101] Example 6

[0102] 41.05 g of washed AKB (DC 95%) was slurried in 80 ml of water and 20 ml of 95 wt% H2SO4. 25 ml of 30 wt% H2O2 was gradually added over two hours. After reduction leaching, the pH of the mixture was 4.76. Residual solids were removed from 90 ml of the solution by filtration. The filtrate was heated to boiling point, and excess water was removed by evaporation. After the mixture began to form crystals, the reaction was continued under reflux cooling for 1 hour. 26.24 g of crystals (DC 81.22%) were removed from 30 ml of the mother liquor by filtration using a hot filtration apparatus. A sample was analyzed by MP-AES, and the results are presented in Table 17.

[0103] Table 17. Composition of the leachate of AKB and the resulting crystals from the crystallization

[0104] element leachate crystals Ca <500 <5000 K 4 670 8 030 Mn 81 000 225 000 Zn 47 500 93 800

[0105] 6.30 g of crystals from the previous step and 10.01 g of technical manganese sulfate hydrate were dissolved in 40 ml of water to form a solution with a pH of 6.37 and a volume of 44 ml. The solution was then circulated through a 30 ml Lanxess MonoPlus TP220 for four hours. Prior to ion exchange, the resin was pretreated with 40 ml of 10 wt% NH₄OH. After ion exchange, 52 ml of raffinate was collected from the column. Zinc was extracted from the resin using 40 ml of 20 wt% H₂SO₄, and a series of eluate samples were collected, with volumes of 12 ml, 43 ml, 45 ml, and 26 ml, respectively. The samples were analyzed by MP-AES, and the results are presented in Table 18.

[0106] Table 18. Composition of dissolved manganese sulfate solution, raffinate and eluate

[0107]

[0108]

[0109] Example 7

[0110] 40.50 g of washed AKB (DC 95%) was slurried in 80 ml of water and 20 ml of 95 wt% H2SO4. 25 ml of 30 wt% H2O2 was gradually added over three to four hours. After reduction leaching, the pH of the mixture was adjusted from 4.91 to 5.54 using a slurry of 4.14 g of Ca(OH)2 in water. Residual solids were removed from 95 ml of the solution by filtration. The filtrate was heated to boiling point, and excess water was removed by evaporation. After the mixture began to form crystals, the reaction was continued under reflux cooling for one hour. 17.68 g of crystals (DC 79.36%) were removed from 27 ml of the mother liquor by filtration using a hot filtration apparatus. A sample was analyzed by MP-AES, and the results are presented in Table 19.

[0111] Table 19. Composition of the leachate from AKB leaching and the resulting crystals from crystallization

[0112] element leachate crystals Ca <500 <5000 K 3 710 4 830 Mn 65 400 246 000 Zn 34 100 98 500

[0113] 8.53 g of crystals from the previous step and 8.26 g of technical manganese sulfate hydrate were dissolved in 40 ml of water to form a 40 ml solution with a pH of 6.02. The solution was then circulated through a 30 ml Lanxess MonoPlus TP220 for four hours. Prior to ion exchange, the resin was pretreated with 40 ml of 10 wt% NH₄OH. After ion exchange, 42 ml of raffinate was collected from the column. Zinc was extracted from the resin using 40 ml of 20 wt% H₂SO₄, and a series of eluate samples were collected, with volumes of 15 ml, 41 ml, 38 ml, and 18 ml, respectively. The samples were analyzed by MP-AES, and the results are presented in Table 20.

[0114] Table 20. Composition of dissolved manganese sulfate solution, raffinate and eluate

[0115] element liquid Raffinate Eluent 1 Eluent 2 Eluent 3 Eluent 4 Ca <500 <500 <500 <500 <500 <500 K 920 680 <50 <50 <50 <50 Mn 93 800 64 800 10 110 40 <5 Zn 11 500 <50 500 8 550 1 980 <250

[0116] Example 8

[0117] 24.56 g of AKB and 20.36 g of AM were slurried in 55 ml of water and 20 ml of 95% H₂SO₄. 25 ml of 30 wt% H₂O₂ were gradually added over three to four hours. After reduction leaching, the pH of the mixture was adjusted from 0.17 to 5.77 using a slurry of 8.71 g of Ca(OH)₂ in water. Residual solids were removed from 70 ml of the solution by filtration. The filtrate was heated to boiling point, and excess water was removed by evaporation. After the mixture began to form crystals, the reaction was continued under reflux cooling for one hour. 9.39 g of crystals (DC 84.35%) were removed from 33 ml of the mother liquor by filtration using a hot filtration apparatus. A sample was analyzed by MP-AES, and the results are presented in Table 21.

[0118] Table 21. Composition of the leachate from AKB leaching and the resulting crystals from crystallization

[0119] element leachate crystals Ca <500 <5 000 K 10 700 30 800 Mn 104 000 262 000 Zn 25 100 22 400

[0120] The crystals from the previous step were dissolved in 20 ml of water to form a solution with a pH of 6.46 and a volume of 24 ml. The solution was then circulated through a 30 ml Lanxess MonoPlus TP220 for four hours. Prior to ion exchange, the resin was pretreated with 40 ml of 10 wt% NH₄OH. After ion exchange, 47 ml of raffinate was collected from the column. Zinc was extracted from the resin using 40 ml of 20 wt% H₂SO₄, and a series of eluate samples were collected, with volumes of 14 ml, 30 ml, 40 ml, and 40 ml, respectively. The samples were analyzed by MP-AES, and the results are presented in Table 22.

[0121] Table 22. Composition of dissolved manganese sulfate solution, raffinate and eluate

[0122] element liquid Raffinate Eluent 1 Eluent 2 Eluent 3 Eluent 4 Ca <500 <500 <500 <500 <500 <500 K 6 870 3 050 <50 <50 <50 <50 Mn 54 300 20 900 50 440 230 100 Zn 4 560 <50 <250 2 850 1 310 <250

[0123] Example 9

[0124] 70 mL of the AKB and AM mixture was passed through 40 mL of untreated lutidine ion exchange resin, and 78 mL of solution was recovered from the column. The resin was first rinsed with water, then eluted with 50 mL of 20 wt% H₂SO₄, and a series of approximately 13 mL aliquots were collected. The samples were analyzed by MP-AES, and the results are presented in Table 23.

[0125] Table 23. Composition of dissolved manganese sulfate solution, raffinate and eluate

[0126] element liquid Raffinate Eluent 1 Eluent 2 Eluent 3 Eluent 4 Ca 380 240 <60 <60 <60 <60 K 1 040 500 <60 <50 <50 <50 Mn 39 710 23 870 <5 10 8 <5 Zn 4 900 120 60 3 200 2 390 220

[0127] A summary of the relevant parameter differences among Examples 1 to 8 is provided in Table 24.

[0128] Table 24. Summary of parameters used in the disclosed examples

[0129]

[0130]

[0131] Based on the above experiments, when comparing Examples 1-8 with Example 9 without resin pretreatment, it can be concluded that the process works with or without AKB washing, in several pH ranges, and preferably with resin pretreatment. Similarly, the process is applicable to different manganese sources.

Claims

1. A method for recovering metals from ground alkaline batteries comprising the following steps: a. selectively leaching manganese and zinc from basic black under reducing conditions by: mixing basic black and a material containing manganese oxide and / or manganese sulfate with a sulfuric acid solution at a leaching temperature of 15-40 ℃ for 1-5 hours to obtain a mixture; b. filtering the mixture to obtain a filtrate of manganese sulfate and zinc sulfate and a filter cake of Pb / Ca / organic matter; c. heating the manganese sulfate and zinc sulfate filtrate to a crystallization temperature of 70-100°C and maintaining the crystallization temperature under reflux cooling for at least 30 minutes to precipitate manganese in the form of sulfate crystals; d. filtering the sulfate crystals and obtaining a manganese-depleted filtrate; e. dissolving the sulfate crystals in water to obtain a sulfate solution, and separating manganese and zinc by chelate ion exchange.

2. The recycling method according to claim 1, wherein: The material containing manganese oxide is MnO2.

3. The recycling method according to claim 2, wherein: The material containing manganese oxide is anode mud.

4. The recycling method according to claim 1, wherein: The material containing manganese oxide is manganese trioxide.

5. The recycling method according to claim 1, wherein: The manganese sulfate and zinc sulfate filtrate obtained in the filtration step (step b) has a manganese to zinc ratio between 10:1 and 3.6:

1.

6. The recycling method according to claim 5, wherein: The manganese sulfate and zinc sulfate filtrate obtained in the filtration step (step b) has a manganese to zinc ratio between 7:1 and 5:

1.

7. The recycling method according to claim 5, wherein: Manganese sulfate is added in the stage before the chelate ion exchange to adjust the manganese to zinc ratio.

8. The recycling method according to claim 1, wherein: The mixture to be filtered in the filtration step (step b) has a pH between 1.5 and 7.

9. The recycling method according to claim 1, wherein: The sulfate solution from which manganese and zinc are separated has a pH between 1.5 and 7 before entering the chelate ion exchange in step (e).

10. The recycling method according to claim 8, wherein: Prior to the filtration step (step b), the pH is adjusted upwards with a hydroxide solution or downwards with sulfuric acid.

11. The recycling method according to claim 9, wherein: In the stage prior to the chelate ion exchange, the pH is adjusted upward with hydroxide solution and downward with sulfuric acid.

12. The recovery method according to claim 10 or 11, wherein: The hydroxide includes NH4OH, NaOH or KOH.

13. The recycling method according to claim 1, wherein: Prior to the selective leaching step (step a), the alkaline black is washed by mixing it with water at a temperature between 5°C and 100°C for at least 30 minutes.

14. The recycling method according to claim 13, wherein: The basic black is mixed with water at a temperature between 20°C and 25°C.

15. The recovery method according to claim 13 or 14, wherein: The basic black was mixed with water for 1-2 hours.

16. The recycling method according to claim 1, wherein: The manganese-depleted filtrate obtained from filtering the sulfate crystals is returned to the leaching step (step a).

17. The recycling method according to claim 1, wherein: In the chelate ion exchange step, the sulfate form of the BPA resin was used.

18. The recycling method according to claim 17, wherein: The sulfate form of the BPA resin was pretreated with ammonium hydroxide, sodium hydroxide, or potassium hydroxide.

19. The recycling method according to claim 1, wherein: In the selective leaching step (step a), the reducing agent is added during the mixing until the manganese and zinc are dissolved.

20. The recycling method according to claim 19, wherein: The reducing agent includes hydrogen peroxide or sulfur dioxide.

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