A method for extracting lithium from waste ternary lithium batteries to prepare lithium carbonate

Abstract

The invention discloses a method for preparing lithium carbonate by extracting lithium from waste ternary lithium batteries, belonging to the technical field of waste ternary lithium battery recycling. The waste ternary lithium batteries are completely discharged and mechanically crushed to obtain ternary lithium battery crushed materials, and primary powder, secondary powder and secondary non-powder solid waste are obtained through two-step screening; the secondary non-powder solid waste is washed with distilled water and the washing wastewater is collected, the primary powder, the secondary powder and the washing wastewater are mixed and then subjected to chemical aluminum removal treatment to obtain wet material; the wet material, distilled water and hydrogen peroxide are prepared into a mixed slurry, and a mixed salt solution is obtained after leaching and extraction; the mixed salt solution is desulfurized to obtain an insoluble salt mixture, and reduction roasting, water leaching and chemical conversion are performed to obtain lithium carbonate; no sulfur-containing smoke is generated during the reduction roasting process, which is more environmentally friendly and safe; after water leaching and chemical conversion operation, the purity of the lithium carbonate is greater than 99.60%, which is conducive to reuse as ternary lithium battery materials.

Description

Technical Field

[0001] The invention belongs to the technical field of ternary lithium battery recycling, and specifically relates to a method for extracting lithium from waste ternary lithium batteries to prepare lithium carbonate. Background Art

[0002] Lithium-ion batteries have many advantages such as high energy density, excellent cycle performance, high charging efficiency, low self-discharge, and no memory effect. They are widely used in power batteries and other energy storage materials to produce new energy electric vehicles and daily consumer electronic products. Ternary polymer lithium batteries refer to lithium batteries whose positive electrode materials use ternary positive electrode materials of lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide. Ternary composite positive electrode materials are made of nickel salt, cobalt salt, and manganese salt. The ratio of nickel, cobalt, and manganese can be adjusted according to actual needs. The ternary composite positive electrode materials are combined with negative electrode materials, electrolytes, diaphragms and other materials to prepare ternary lithium batteries. Batteries with ternary materials as positive electrodes are safer than cobalt oxide lithium batteries.

[0003] The natural reserves of lithium in the earth's crust are 11 million tons, accounting for about 0.0065% of the elements in the earth's crust. In nature, lithium mainly exists in the form of salt lake brine, spodumene, lithium mica and aluminum phosphate ore. Lithium is mainly extracted from lithium-containing ores and salt lake brine. Spodumene ore has low grade, unstable quality, high mining and selection costs, and the ore mainly relies on imports; the lithium content in salt lake brine is low, the magnesium-lithium ratio is high, and impurity removal is complicated, so the recycling of secondary lithium resources is becoming more and more important. The invention patent application with publication number CN108220607A discloses a method for recovering lithium from lithium-containing electrode waste, comprising: calcining the lithium-containing electrode waste in a reducing atmosphere, cooling the reduced material in a protective atmosphere after calcination, leaching the reduced material, and performing solid-liquid separation to obtain a lithium-containing solution and solid slag, and preparing the lithium-containing solution into a lithium-containing product. The protective atmosphere of the method includes sulfur dioxide and nitrogen dioxide atmospheres, and the lithium-containing electrode waste is not treated, which is prone to pollution. Subsequent environmental protection treatment is time-consuming and labor-intensive, so a low-pollution method for extracting lithium to prepare lithium carbonate is proposed. Summary of the invention

[0004] The purpose of the present invention is to provide a method for extracting lithium from waste ternary lithium batteries to prepare lithium carbonate, so as to solve the problems in the background technology.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for extracting lithium from waste ternary lithium batteries to prepare lithium carbonate comprises the following steps:

[0007] Step 1: Immerse the recycled waste ternary lithium battery in a 5% sodium chloride solution for 24-48 hours, remove the fully discharged waste ternary lithium battery and wash it with distilled water for 1-2 times, and then dry it with air at 40-50°C;

[0008] Step 2: Mechanically crush the dried waste ternary lithium battery under the condition of spraying liquid nitrogen to obtain ternary lithium battery crushed materials, transfer the ternary lithium battery crushed materials to a vacuum rake drying equipment while they are still cold, bake them at 0-0.1MPa and 160-180℃ for 15-30min, extract the volatile gas, condense the volatile gas and recover the electrolyte;

[0009] Step 3: Separate the baked ternary lithium battery crushed materials with a vibrating screening device to screen out primary powder and primary non-powder solid waste, perform a second mechanical crushing on the primary non-powder solid waste, and then perform a second separation with a vibrating screening device again to screen out secondary powder and secondary non-powder solid waste;

[0010] Step 4: Wash the secondary non-powder solid waste with distilled water for 2-3 times, filter, separate the washing wastewater and intercept and collect plastic solid waste and metal solid waste; mix the primary powder, secondary powder and washing wastewater, then add distilled water to adjust the solid-liquid ratio to 10g / L, then add sodium hydroxide, adjust the concentration of sodium hydroxide to 40±0.5g / L, stir at 50-60°C for 1.5-3h, filter, and then wash the filter cake with sodium hydroxide solution for 2-3 times, the aluminum therein is removed to form sodium aluminate, and the chemical dealuminization treatment is completed to obtain wet material;

[0011] Step 5: Mix the wet material, distilled water and 20% hydrogen peroxide by mass into a mixed slurry with a solid content of 5-10%, stir and react at 60° C. for 1-1.5 hours, then inject concentrated sulfuric acid into the mixed slurry and stir continuously, adjust the sulfuric acid concentration to 1-1.5 mol / L, extract at 60° C. for 1.5-2 hours, filter and collect the filtrate, wash the filter cake with distilled water for 2-3 times, and mix the washing water and the filtrate to obtain a mixed salt solution;

[0012] Step 6: Add the mixed salt solution and urea into a vacuum stirring kettle, stir for 6-7 hours at 100-110°C and 500-800r / min, filter while hot, collect the filtrate, wash the filter cake with distilled water 2-3 times, vacuum dry, crush, and complete the desulfurization treatment to obtain an insoluble salt mixture; mix the filtrate and washing water to obtain tail water, and recover ammonium sulfate by MVR evaporation and crystallization of the tail water;

[0013] Step 7: reducing and roasting the insoluble salt mixture at 1200-1300° C. in a mixed gas atmosphere for 4-6 hours to obtain a mixed material; stirring and mixing the mixed material with distilled water after vacuum deoxygenation treatment, soaking in water under nitrogen protection for 5-10 hours, filtering, and obtaining a filter residue and a lithium-containing filtrate;

[0014] Step 8: Transfer the lithium-containing filtrate to a vacuum reactor, introduce carbon dioxide gas into the vacuum reactor at 25-30°C to maintain the pressure of the vacuum reactor at 2.5-3MPa, react until the solid-liquid ratio in the vacuum reactor remains unchanged, filter, vacuum dry the filtrate, and complete the chemical conversion treatment to obtain lithium carbonate.

[0015] Furthermore, the dosage ratio of the mixed salt solution to urea is 100 mL: 10-15 g.

[0016] Furthermore, the mixed gas is a mixture of carbon monoxide and hydrogen in a dosage ratio of 4-5 mol:1 mol.

[0017] Beneficial effects of the present invention:

[0018] The method for preparing lithium carbonate from waste ternary lithium batteries of the present invention is more environmentally friendly, is conducive to reducing the release of harmful gases during reduction roasting, and the prepared lithium carbonate has a higher purity. After the waste ternary lithium batteries are fully discharged, they are mechanically crushed under liquid nitrogen conditions, which is conducive to preventing the waste ternary lithium batteries from being squeezed and exploding, and is safer; the electrolyte is removed during the roasting process of the ternary lithium battery crushed materials, which is conducive to the recycling of the electrolyte of the ternary lithium battery; through multi-stage vibration screening and washing of secondary non-powder solid waste, the battery waste containing lithium elements is fully recovered, which is conducive to increasing the recovery rate of lithium; after chemical aluminum removal and desulfurization treatment, no sulfur-containing smoke is generated during the reduction roasting process, which is more environmentally friendly and safe, and the chemical conversion operation combined with water immersion is conducive to improving the purity of lithium carbonate, and the purity of lithium carbonate is greater than 99.60%, which is conducive to reuse in ternary lithium batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the accompanying drawings.

[0020] Figure 1 The present invention is a flow chart of extracting lithium from waste ternary lithium batteries to prepare lithium carbonate. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1

[0023] See also Figure 1 , preparing lithium carbonate by extracting lithium from waste ternary lithium batteries, comprising the following steps:

[0024] Step 1: Immerse the recycled waste ternary lithium battery in a 5% sodium chloride solution for 24 hours, remove the fully discharged waste ternary lithium battery and wash it once with distilled water, and then dry it with air at 40°C;

[0025] Step 2: Mechanically crush the dried waste ternary lithium battery under the condition of spraying liquid nitrogen to obtain ternary lithium battery crushed materials, transfer the ternary lithium battery crushed materials to a vacuum rake drying device while they are still cold, bake them at 0 MPa and 160°C for 15 minutes, extract the volatile gas, condense the volatile gas and recover the electrolyte;

[0026] Step 3: Separate the baked ternary lithium battery crushed materials with a vibrating screening device to screen out primary powder and primary non-powder solid waste, perform a second mechanical crushing on the primary non-powder solid waste, and then perform a second separation with a vibrating screening device again to screen out secondary powder and secondary non-powder solid waste;

[0027] Step 4: Wash the secondary non-powder solid waste twice with distilled water, filter, separate the washing wastewater and intercept and collect plastic solid waste and metal solid waste; mix the primary powder, secondary powder and washing wastewater, then add distilled water to adjust the solid-liquid ratio to 10 g / L, then add sodium hydroxide, adjust the concentration of sodium hydroxide to 40±0.5 g / L, stir at 50°C for 1.5h, filter, and then wash the filter cake twice with sodium hydroxide solution, the aluminum therein is removed to form sodium aluminate, and the chemical dealuminization treatment is completed to obtain wet material;

[0028] Step 5: The wet material, distilled water and 20% by mass of hydrogen peroxide are mixed into a mixed slurry with a solid content of 5%, and the mixture is stirred at 60° C. for 1 hour, and then concentrated sulfuric acid is injected into the mixed slurry and stirred continuously, and the sulfuric acid concentration is adjusted to 1 mol / L, and the mixture is leached and extracted at 60° C. for 1.5 hours, and the filtrate is collected by filtration, and the filter cake is washed twice with distilled water, and the washing water and the filtrate are mixed to obtain a mixed salt solution;

[0029] Step 6: Add the mixed salt solution and urea into a vacuum stirred tank, the ratio of the mixed salt solution to urea is 100mL:10g, stir for 6h at 100°C and 500r / min, the urea solution is converted into ammonia water and carbon dioxide after heating, and the soluble sulfate is converted into insoluble carbonate, filter while hot, collect the filtrate, wash the filter cake twice with distilled water, vacuum dry, crush, complete the desulfurization treatment to obtain an insoluble salt mixture; mix the filtrate and washing water to obtain tail water, and recover ammonium sulfate by MVR evaporation and crystallization of the tail water;

[0030] Step 7: reducing and roasting the insoluble salt mixture at 1200° C. in a mixed gas atmosphere for 4 hours to obtain a mixed material; the mixed gas is a mixture of carbon monoxide and hydrogen in a ratio of 4 mol:1 mol; stirring and mixing the mixed material with distilled water after vacuum deoxygenation treatment, soaking in water under nitrogen protection for 5 hours, filtering, and obtaining a filter residue and a lithium-containing filtrate;

[0031] Step 8: Transfer the lithium-containing filtrate to a vacuum reactor, introduce carbon dioxide gas into the vacuum reactor at 25°C, maintain the pressure of the vacuum reactor at 2.5MPa, react until the solid-liquid ratio in the vacuum reactor remains unchanged, filter, vacuum dry the filtrate, and complete the chemical conversion treatment to obtain lithium carbonate. After component analysis, the purity of lithium carbonate is >99.60%.

[0032] Example 2

[0033] See also Figure 1 , preparing lithium carbonate by extracting lithium from waste ternary lithium batteries, comprising the following steps:

[0034] Step 1: Immerse the recycled waste ternary lithium battery in a 5% sodium chloride solution for 36 hours, remove the fully discharged waste ternary lithium battery and wash it once with distilled water, and then dry it with air at 45°C;

[0035] Step 2: Mechanically crush the dried waste ternary lithium battery under the condition of spraying liquid nitrogen to obtain ternary lithium battery crushed materials, transfer the ternary lithium battery crushed materials to a vacuum rake drying equipment while they are still cold, bake them at 0.05MPa and 170°C for 20min, extract the volatile gas, condense the volatile gas and recover the electrolyte;

[0036] Step 3: Separate the baked ternary lithium battery crushed materials with a vibrating screening device to screen out primary powder and primary non-powder solid waste, perform a second mechanical crushing on the primary non-powder solid waste, and then perform a second separation with a vibrating screening device again to screen out secondary powder and secondary non-powder solid waste;

[0037] Step 4: Wash the secondary non-powder solid waste twice with distilled water, filter, separate the washing wastewater and intercept and collect plastic solid waste and metal solid waste; mix the primary powder, secondary powder and washing wastewater, then add distilled water to adjust the solid-liquid ratio to 10 g / L, then add sodium hydroxide, adjust the concentration of sodium hydroxide to 40±0.5 g / L, stir at 55°C for 2h, filter, and then wash the filter cake twice with sodium hydroxide solution, the aluminum therein is removed to form sodium aluminate, and the chemical dealuminization treatment is completed to obtain wet material;

[0038] Step 5: The wet material, distilled water and 20% by mass of hydrogen peroxide are mixed into a mixed slurry with a solid content of 8%, and the mixture is stirred at 60° C. for 1.2 hours, and then concentrated sulfuric acid is injected into the mixed slurry and stirred continuously, and the sulfuric acid concentration is adjusted to 1.2 mol / L, and the mixture is leached and extracted at 60° C. for 1.8 hours, and the filtrate is collected by filtration, and the filter cake is washed twice with distilled water, and the washing water and the filtrate are mixed to obtain a mixed salt solution;

[0039] Step 6: Add the mixed salt solution and urea into a vacuum stirred tank, the ratio of the mixed salt solution to urea is 100mL:12g, stir at 105°C and 600r / min for 6.5h, the urea solution is converted into ammonia water and carbon dioxide after heating, and the soluble sulfate is converted into insoluble carbonate, filter while hot, collect the filtrate, wash the filter cake twice with distilled water, vacuum dry, crush, complete the desulfurization treatment to obtain an insoluble salt mixture; mix the filtrate and washing water to obtain tail water, and recover ammonium sulfate by MVR evaporation and crystallization of the tail water;

[0040] Step 7: reducing and roasting the insoluble salt mixture at 1250° C. in a mixed gas atmosphere for 5 hours to obtain a mixed material; the mixed gas is a mixture of carbon monoxide and hydrogen in a ratio of 4.5 mol:1 mol; stirring and mixing the mixed material with distilled water after vacuum deoxygenation treatment, soaking in water under nitrogen protection for 8 hours, filtering, and obtaining a filter residue and a lithium-containing filtrate;

[0041] Step 8: Transfer the lithium-containing filtrate to a vacuum reactor, introduce carbon dioxide gas into the vacuum reactor at 28°C, maintain the pressure of the vacuum reactor at 2.8MPa, react until the solid-liquid ratio in the vacuum reactor remains unchanged, filter, vacuum dry the filtrate, and complete the chemical conversion treatment to obtain lithium carbonate. After component analysis, the purity of lithium carbonate is >99.60%.

[0042] Example 3

[0043] See also Figure 1 , preparing lithium carbonate by extracting lithium from waste ternary lithium batteries, comprising the following steps:

[0044] Step 1: Immerse the recycled waste ternary lithium battery in a 5% sodium chloride solution for 48 hours, remove the fully discharged waste ternary lithium battery and wash it twice with distilled water, and then dry it at 50°C with air blast;

[0045] Step 2: Mechanically crush the dried waste ternary lithium battery under the condition of spraying liquid nitrogen to obtain ternary lithium battery crushed materials, transfer the ternary lithium battery crushed materials to a vacuum rake drying device while they are still cold, bake them at 0.1 MPa and 180°C for 30 minutes, extract the volatile gas, condense the volatile gas and recover the electrolyte;

[0046] Step 3: Separate the baked ternary lithium battery crushed materials with a vibrating screening device to screen out primary powder and primary non-powder solid waste, perform a second mechanical crushing on the primary non-powder solid waste, and then perform a second separation with a vibrating screening device again to screen out secondary powder and secondary non-powder solid waste;

[0047] Step 4: Wash the secondary non-powder solid waste with distilled water for 3 times, filter, separate the washing wastewater and intercept and collect plastic solid waste and metal solid waste; mix the primary powder, secondary powder and washing wastewater, then add distilled water to adjust the solid-liquid ratio to 10 g / L, then add sodium hydroxide, adjust the concentration of sodium hydroxide to 40±0.5 g / L, stir at 60°C for 3h, filter, and then wash the filter cake with sodium hydroxide solution for 3 times, the aluminum therein is removed to form sodium aluminate, and the chemical dealuminization treatment is completed to obtain wet material;

[0048] Step 5: The wet material, distilled water and 20% by mass of hydrogen peroxide are mixed into a mixed slurry with a solid content of 10%, and the mixture is stirred at 60° C. for 1.5 hours, and then concentrated sulfuric acid is injected into the mixed slurry and stirred continuously, and the sulfuric acid concentration is adjusted to 1.5 mol / L, and the mixture is leached and extracted at 60° C. for 2 hours, and the filtrate is collected by filtration, and the filter cake is washed with distilled water for 3 times, and the washing water and the filtrate are mixed to obtain a mixed salt solution;

[0049] Step 6: Add the mixed salt solution and urea into a vacuum stirred tank, the ratio of the mixed salt solution to urea is 100mL:15g, stir at 110°C and 800r / min for 7h, the urea solution is converted into ammonia water and carbon dioxide after heating, and the soluble sulfate is converted into insoluble carbonate, filter while hot, collect the filtrate, wash the filter cake with distilled water for 3 times, vacuum dry, crush, complete the desulfurization treatment to obtain an insoluble salt mixture; mix the filtrate and washing water to obtain tail water, and recover ammonium sulfate by MVR evaporation and crystallization of the tail water;

[0050] Step 7: reducing and roasting the insoluble salt mixture at 1300° C. in a mixed gas atmosphere for 6 hours to obtain a mixed material; the mixed gas is a mixture of carbon monoxide and hydrogen in a ratio of 5 mol:1 mol; stirring and mixing the mixed material with distilled water after vacuum deoxygenation treatment, soaking in water under nitrogen protection for 10 hours, filtering, and obtaining a filter residue and a lithium-containing filtrate;

[0051] Step 8: Transfer the lithium-containing filtrate to a vacuum reactor, introduce carbon dioxide gas into the vacuum reactor at 30°C, maintain the pressure of the vacuum reactor at 3MPa, react until the solid-liquid ratio in the vacuum reactor remains unchanged, filter, vacuum dry the filtrate, and complete the chemical conversion treatment to obtain lithium carbonate. After component analysis, the purity of lithium carbonate is >99.60%.

[0052] It should be noted that, in this article, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0053] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for extracting lithium from waste ternary lithium batteries to prepare lithium carbonate, characterized in that: The steps include: Step 1: The used ternary lithium battery is completely discharged and dried, and mechanically crushed to obtain ternary lithium battery scraps, and after baking to recover the electrolyte, the ternary lithium battery scraps are screened in two steps to obtain primary powder, secondary powder and secondary non-powder solid waste; Step 2: washing the secondary non-powder solid waste with distilled water and collecting the washing wastewater, mixing the primary powder, the secondary powder and the washing wastewater and performing chemical aluminum removal treatment to obtain a wet material; Step 3: prepare a mixed slurry with the wet material, distilled water and hydrogen peroxide, stir and react at 60° C. for 1-1.5 hours, add concentrated sulfuric acid to a concentration of 1-1.5 mol / L, extract for 1.5-2 hours, filter and collect the filtrate, wash the filter cake with distilled water for 2-3 times, and mix the washing water and the filtrate to obtain a mixed salt solution; Step 4: desulfurizing the mixed salt solution to obtain an insoluble salt mixture and tail water, evaporating and crystallizing the tail water to recover ammonium sulfate, reducing and roasting the insoluble salt mixture at 1200-1300° C. in a mixed gas atmosphere for 4-6 hours to obtain a mixed material, soaking the mixed material in water under nitrogen protection for 5-10 hours, filtering to obtain a filter residue and a lithium-containing filtrate, and chemically converting the lithium-containing filtrate to obtain lithium carbonate; The specific steps of chemical aluminum removal are as follows: The mixed primary powder, secondary powder and washing wastewater are mixed, and distilled water is added to adjust the solid-liquid ratio to 10 g / L, and then sodium hydroxide is added and the concentration of sodium hydroxide is adjusted to 40±0.5 g / L, and stirred at 50-60°C for 1.5-3h, filtered, and then the filter cake is washed with sodium hydroxide solution for 2-3 times to obtain a wet material; The specific steps of the desulfurization treatment are as follows: The mixed salt solution and urea are stirred at 100-110°C and 500-800r / min for 6-7h, filtered while hot, and the filtrate is collected. The filter cake is washed with distilled water, dried, and crushed to obtain an insoluble salt mixture; the filtrate is mixed with washing water to obtain tail water; The dosage ratio of the mixed salt solution and urea is 100mL:10-15g; The mixed gas in step 4 is a mixture of carbon monoxide and hydrogen in a molar ratio of 4-5:1; The specific steps of the chemical conversion treatment are as follows: The lithium-containing filtrate is transferred to a vacuum reactor, and carbon dioxide gas is introduced into the vacuum reactor at 25-30° C. to maintain the pressure of the vacuum reactor at 2.5-3 MPa, and the reaction is performed until the solid-liquid ratio remains unchanged, and the filtrate is filtered and dried to obtain lithium carbonate.

2. The method for preparing lithium carbonate from waste ternary lithium batteries according to claim 1, characterized in that: The solid content of the mixed slurry in step 3 is 5-10%.

3. The method for preparing lithium carbonate from waste ternary lithium batteries according to claim 1, characterized in that: The specific steps of the two-step screening are as follows: The baked ternary lithium battery crushed materials are separated by a vibrating screening device to separate primary powder and primary non-powder solid waste. The primary non-powder solid waste is mechanically crushed and separated by a vibrating screening device to separate secondary powder and secondary non-powder solid waste.

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