A method for recovering valuable metal ions in lithium battery separators

Abstract

The invention discloses a method for recovering valuable metal ions in a lithium battery separator, comprising the following steps: (1) crushing the lithium battery separator and performing three-stage countercurrent acid leaching, solid-liquid separation, and obtaining waste residue and enriched liquid, wherein the acid solution used in the three-stage countercurrent acid leaching is a mixed solution of sulfuric acid and hydrochloric acid; (2) adding alkali liquor to the enriched liquid obtained in step (1) to adjust the pH to 4-6, and after a precipitation reaction, solid-liquid separation is performed to obtain a filter cake and a filtrate; (3) adding alkali liquor to the filtrate obtained in step (2) to adjust the pH to alkaline, and after a precipitation reaction, solid-liquid separation is performed to obtain a solid phase, and the solid phase is washed to obtain nickel-cobalt-manganese hydroxide; (4) after the filter cake obtained in step (2) is roasted, water is added to dissolve it, and filtering is performed to obtain a solution rich in lithium ions and iron-aluminum slag. This method can improve the extraction rate of lithium ions in the separator, and can also extract metal ions of nickel, cobalt, manganese, etc., thereby greatly utilizing the value of waste separators.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery recycling, and in particular relates to a method for recycling valuable metal ions in lithium battery separators. Background Art

[0002] At present, power batteries are mainly lithium batteries. As the use of lithium batteries increases, the amount of waste lithium batteries also gradually increases. A large amount of lithium battery separators will be obtained during the processing of waste lithium batteries. Lithium battery separators contain rich metallic lithium and also contain valuable metal materials such as nickel, cobalt, and manganese. Therefore, the recycling and treatment of lithium battery separators is particularly important.

[0003] Existing lithium battery separators are mainly processed by thermal decomposition, which requires high energy consumption and has a low metal extraction rate. Summary of the Invention

[0004] The present invention aims to address at least one of the technical problems existing in the prior art. To this end, the present invention provides a method for recovering valuable metal ions from lithium battery separators. This method can improve the extraction rate of lithium ions from the separator while also extracting metal ions such as nickel, cobalt, and manganese, thereby maximizing the value of waste separators.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions:

[0006] A method for recovering valuable metal ions in a lithium battery separator comprises the following steps: (1) crushing the lithium battery separator and performing three-stage countercurrent acid leaching, solid-liquid separation, and obtaining waste residue and enriched liquid, wherein the acid used in the three-stage countercurrent acid leaching is a mixed solution of sulfuric acid and hydrochloric acid; (2) adding alkali solution to the enriched liquid obtained in step (1) to adjust the pH to 4-6, causing a precipitation reaction, and then performing solid-liquid separation to obtain a filter cake and a filtrate; (3) adding alkali solution to the filtrate obtained in step (2) to adjust the pH to alkaline, causing a precipitation reaction, and then performing solid-liquid separation to obtain a solid phase, and washing the solid phase to obtain nickel-cobalt-manganese hydroxide; and (4) roasting the filter cake obtained in step (2), dissolving it in water, and filtering to obtain a lithium ion-rich solution and iron-aluminum slag.

[0007] Preferably, in step (1), the acid solution used in the tertiary countercurrent acid leaching is a mixture of 20% sulfuric acid and 20% hydrochloric acid in a volume ratio of (20-40):1.

[0008] Preferably, in step (1), the liquid-to-solid ratio of the acid solution used in the three-stage countercurrent acid leaching to the lithium battery separator is (5-20) mL:1 g.

[0009] Preferably, in step (1), the time of the three-stage countercurrent acid leaching is 1-5 hours.

[0010] Preferably, in step (2) and step (3), the alkali solution is at least one of a sodium hydroxide solution and a potassium hydroxide solution, and the concentration of the alkali solution is 1-3 mol / L.

[0011] Preferably, in step (2), the molar ratio of the metal ions in the enriched solution to the hydroxide ions in the alkaline solution is 1:(1-3).

[0012] Preferably, in step (3), adjusting the pH to be alkaline means adjusting the pH to 10-12.

[0013] Preferably, in step (3), the molar ratio of the metal ions in the filtrate to the hydroxide ions in the alkali solution is 1:(1-4).

[0014] Preferably, in step (4), the calcination temperature is 400-600° C., and the calcination time is 1-3 hours.

[0015] Preferably, in step (4), the mass ratio of the filter cake to the water added for dissolution is 1:(10-100).

[0016] Further preferably, in step (4), the mass ratio of the filter cake to the water added for dissolution is 1:(10-50).

[0017] Preferably, in step (4), the ferroaluminum slag is a mixed solid of iron oxide and aluminum oxide.

[0018] The beneficial effects of the present invention are:

[0019] (1) In the method of recovering valuable metal ions in lithium battery separators of the present invention, a small amount of hydrochloric acid is added to the sulfuric acid used in the three-stage countercurrent acid leaching to quickly dissolve the aluminum foil, while providing chloride ions for the subsequent precipitation of lithium ions. This avoids the direct use of sulfuric acid, which results in poor dissolution of the aluminum foil, the direct use of low-concentration hydrochloric acid, which results in poor leaching effect, and the violent and unsafe reaction of high-concentration hydrochloric acid.

[0020] (2) In the method for recovering valuable metal ions in the lithium battery separator of the present invention, the residual valuable metals in the lithium battery separator are ensured to be fully leached by using three-stage countercurrent acid leaching, while the metal ions in the leachate are enriched;

[0021] (3) In the method for recovering valuable metal ions in the lithium battery separator of the present invention, sodium hydroxide is added to adjust the pH of the leaching solution to 4-6. Under the action of sodium hydroxide, aluminum ions react with lithium ions and chloride ions to form LiCl·2Al(OH)3·nH2O co-precipitates. At the same time, iron ions react with sodium hydroxide to form iron hydroxide precipitates. After filtration, an aqueous solution containing nickel, cobalt and manganese ions is obtained. Sodium hydroxide is further added to adjust the pH to 10-12 to obtain nickel, cobalt and manganese hydroxide precipitates, which can be used as raw materials for ternary precursor production after acid dissolution.

[0022] (4) The method of the present invention for recovering valuable metal ions in lithium battery separators has a high extraction rate for nickel, cobalt, and lithium, and can efficiently recover valuable metals from materials with low valuable metal content. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the process of Example 1 of the present invention;

[0024] Figure 2 This is a flow chart of the three-stage countercurrent acid leaching in Example 1 of the present invention. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to specific embodiments.

[0026] The main components of the lithium battery separators used in Examples 1-13 of the present invention are shown in Table 1 below.

[0027] Table 1: Main components of lithium battery separators (%)

[0028] Separator paper Aluminum foil Copper foil anti-fans 86.30 3.34 2.38 7.98

[0029] The main components of the black powder in Table 1 are shown in Table 2 below.

[0030] Table 2: Main components of black powder (%)

[0031] Fe Ni Co Mn Li Acid-insoluble matter 0.62 0.28 0.10 0.65 0.96 5.37

[0032] Example 1:

[0033] A method for recovering valuable metal ions in lithium battery separators, such as Figure 1 As shown, the following steps are included:

[0034] (1) After the lithium battery separator was crushed, 6 groups of samples were taken, each group of samples was 20g, and 300g of mixed acid prepared by mixing 20% sulfuric acid and 20% hydrochloric acid in a volume ratio of 30:1 was added to perform three-stage countercurrent acid leaching (such as Figure 2As shown), the liquid-solid ratio of the mixed acid to the lithium battery separator is 300:20 (ml:g). If the filtrate is less than 300ml, the mixed acid is added to 300ml. The leaching time for each group of samples is 2h. After enrichment, the waste residue and the enriched liquid are obtained by filtration.

[0035] (2) adding 1 mol / l sodium hydroxide solution to the enriched solution obtained in step (1), adjusting the pH to 5, causing a precipitation reaction, and filtering to obtain a filter cake containing LiCl·2Al(OH)3·nH2O and ferric hydroxide and a filtrate L;

[0036] (3) adding 2 mol / l sodium hydroxide solution to the filtrate L obtained in step (2), adjusting the pH to 11 to produce a precipitation reaction, filtering to obtain a solid phase, and washing the solid phase with clean water to obtain nickel cobalt manganese hydroxide, which can be subsequently used as a raw material for generating a ternary positive electrode material;

[0037] (4) The filter cake obtained in step (2) is washed with clean water, and then placed in an electric furnace and roasted at 500° C. for 2 h to obtain aluminum oxide, iron oxide, and lithium oxide. After the roasted filter cake is cooled, water is added to dissolve it in a mass ratio of 1:20 between the filter cake and water, and a high-purity lithium ion solution and an iron-aluminum slag composed of a mixed solid of iron oxide and aluminum oxide are obtained after filtration.

[0038] Example 2:

[0039] A method for recovering valuable metal ions in lithium battery separators, which differs from Example 1 only in that 20% sulfuric acid is used instead of the mixed acid in step (1).

[0040] Example 3:

[0041] A method for recovering valuable metal ions in a lithium battery separator, which differs from Example 1 only in that the time for the three-stage countercurrent acid leaching in step (1) is 1 hour.

[0042] Example 4:

[0043] A method for recovering valuable metal ions in a lithium battery separator, which differs from Example 1 only in that the time for the three-stage countercurrent acid leaching in step (1) is 3 hours.

[0044] Example 5:

[0045] A method for recovering valuable metal ions in a lithium battery separator, which differs from Example 1 only in that the liquid-solid ratio of the mixed acid to the lithium battery separator in step (1) is 100:20 (ml:g).

[0046] Example 6:

[0047] A method for recovering valuable metal ions in a lithium battery separator, which differs from Example 1 only in that the liquid-to-solid ratio of the mixed acid to the lithium battery separator in step (1) is 200:20 (ml:g).

[0048] Example 7:

[0049] A method for recovering valuable metal ions in a lithium battery separator, which differs from Example 1 only in that the liquid-solid ratio of the mixed acid to the lithium battery separator in step (1) is 400:20 (ml:g).

[0050] Example 8:

[0051] A method for recovering valuable metal ions in a lithium battery separator, which differs from Example 1 only in that the calcination temperature in step (4) is 400°C.

[0052] Example 9:

[0053] A method for recovering valuable metal ions in a lithium battery separator, which differs from Example 1 only in that the calcination temperature in step (4) is 600°C.

[0054] Example 10:

[0055] A method for recovering valuable metal ions in a lithium battery separator, which differs from Example 1 only in that the roasting time in step (4) is 1 hour.

[0056] Example 11:

[0057] A method for recovering valuable metal ions in a lithium battery separator, which differs from Example 1 only in that the roasting time in step (4) is 3 hours.

[0058] Example 12:

[0059] A method for recovering valuable metal ions in a lithium battery separator, which differs from Example 1 only in that water is added in step (4) at a solid-liquid ratio of 1:10.

[0060] Example 13:

[0061] A method for recovering valuable metal ions in a lithium battery separator, which differs from Example 1 only in that water is added in step (4) for dissolution at a mass ratio of filter cake to water of 1:30.

[0062] Test example:

[0063] The filtrate L, the iron oxide and aluminum oxide mixed solid (iron-aluminum slag), and the lithium ion solution obtained in the recovery method of Examples 1-13 were subjected to elemental analysis. The results are shown in Table 3:

[0064] Table 3: Element detection results

[0065]

[0066]

[0067]

[0068]

[0069]

[0070] As can be seen from Table 3, the iron oxide and aluminum oxide mixed solids obtained in Examples 1-13 have a nickel content of less than 0.1%, a cobalt content of less than 0.04%, a manganese content of less than 0.4%, and a lithium content of less than 0.6%. The extraction rate of valuable metals such as nickel, cobalt, manganese, and lithium is high, and the lithium ion solution contains no other metal ions and has a high purity. The present invention achieves efficient recovery of low-content valuable metal ions, and simultaneously recovers metal ions such as nickel, cobalt, and manganese in the process of obtaining a high-purity lithium ion solution, thereby reducing the loss of valuable metals.

[0071] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for recovering valuable metal ions in lithium battery separators, characterized by: The following steps are involved: (1) After the lithium battery diaphragm is crushed, a three-stage countercurrent acid leaching is performed to separate the solid and liquid to obtain waste residue and enriched liquid. The acid used in the three-stage countercurrent acid leaching is a mixed solution of sulfuric acid and hydrochloric acid; (2) adding alkaline solution to the enriched solution obtained in step (1) to adjust the pH to 4-6, causing a precipitation reaction, and then performing solid-liquid separation to obtain a filter cake and a filtrate; (3) adding alkali solution to the filtrate obtained in step (2) to adjust the pH to alkaline, causing a precipitation reaction, and then performing solid-liquid separation to obtain a solid phase, and washing the solid phase to obtain nickel-cobalt-manganese hydroxide; (4) roasting the filter cake obtained in step (2), dissolving it in water, and filtering it to obtain a lithium ion-rich solution and iron-aluminum slag; In step (1), the acid solution used in the three-stage countercurrent acid leaching is a mixture of 20% sulfuric acid and 20% hydrochloric acid in a volume ratio of (20-40):1, the liquid-solid ratio of the acid solution used in the three-stage countercurrent acid leaching to the lithium battery separator is (5-20) mL:1 g, and the time of the three-stage countercurrent acid leaching is 1-5 hours; in step (4), the roasting temperature is 400-600°C, the roasting time is 1-3 hours, and the mass ratio of the filter cake to the water added for dissolution is 1:(10-50); in steps (2) and (3), the alkali solution is at least one of a sodium hydroxide solution and a potassium hydroxide solution, and the concentration of the alkali solution is 1-3 mol / L.

2. The method for recovering valuable metal ions in a lithium battery separator according to claim 1, wherein: In step (2), the molar ratio of the metal ions in the enriched solution to the hydroxide ions in the alkaline solution is 1:(1-3).

3. The method for recovering valuable metal ions in a lithium battery separator according to claim 1, wherein: In step (3), adjusting the pH to alkaline means adjusting the pH to 10-12.

4. The method for recovering valuable metal ions in a lithium battery separator according to claim 1, wherein: In step (3), the molar ratio of the metal ions in the filtrate to the hydroxide ions in the alkali solution is 1:(1-4).

5. The method for recovering valuable metal ions in a lithium battery separator according to claim 1, wherein: In step (4), the ferroaluminum slag is a mixed solid of iron oxide and aluminum oxide.

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