Method for preparing battery-grade lithium carbonate from waste ternary lithium battery powder

Abstract

The invention provides a method for preparing battery-grade lithium carbonate from waste ternary lithium battery powder. The method comprises the following steps: performing size mixing on waste ternary lithium battery powder to form slurry, introducing carbon dioxide for primary carbon washing, and filtering to obtain filtrate A and carbon washing slag A; deoiling, defluorinating and pyrolyzing the filtrate A for the first time to obtain crude lithium carbonate A, and grinding the carbon washing slag A for the first time, roasting, grinding for the second time, carbon washing for the second time and filtering to obtain filtrate B and carbon washing slag B; after calcium hydroxide is added into the carbon washing slag B for transformation treatment, crude lithium carbonate B is obtained through lithium extraction, filtration, fluorine and aluminum removal, concentration and precipitation, and then subsequent treatment is conducted. According to the method, the resource recovery efficiency of the waste lithium battery is improved, the targets of reducing the cost and improving the resource utilization rate are achieved by simplifying the process, improving the raw material adaptability and optimizing the lithium recovery process, and the method has relatively high economic and environmental values.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of comprehensive recovery of lithium ion batteries, and particularly relates to a method for preparing battery-grade lithium carbonate from waste ternary lithium battery powder. BACKGROUND

[0002] The disassembly and recycling of waste ternary lithium batteries is an important issue in the field of environmental protection and resource recycling. With the continuous growth of demand for lithium batteries in electric vehicles and consumer electronics, the generation of a large number of waste ternary lithium batteries has brought great pressure on the environment. At the same time, how to efficiently recover valuable elements in waste batteries, especially the extraction of lithium, cobalt, nickel and other metals, has become a technical problem that needs to be solved. The main components of waste ternary lithium batteries include lithium battery positive materials (such as lithium nickel cobalt manganese oxide), negative materials (such as graphite), electrolyte, binder, and a mixture of aluminum powder, copper powder and other metal elements. Due to the differences in chemical properties and the complexity of physical forms between these materials, the disassembly and recycling process is full of technical challenges, especially in the separation process, there are significant processing difficulties.

[0003] In the disassembly process of waste ternary lithium batteries, the separation of aluminum, silicon, fluorine and other impurities is one of the biggest technical difficulties. Aluminum is usually closely combined with the battery shell material, while the electrolyte in the lithium battery contains organic solvents and fluorine elements. In the decomposition and disassembly process of the battery, the volatilization and transfer of fluorine make its content in the disassembly residue relatively high, usually between 1.5%-3.5%. At the same time, the presence of negative materials (such as graphite) and binders in the battery also makes the content of carbon and fluorine elements in the battery relatively high, further increasing the separation difficulty in the recycling process. The high content of fluorine in the battery not only increases the harm to the environment, but also causes great technical problems in the subsequent recycling process. Silicon is usually used in some specific battery types, such as silicon-based negative materials, and its recovery after disassembly also faces great difficulty, usually with a content of 1.0%-2.5%. These factors make the recovery efficiency of waste ternary lithium battery disassembly material not high, and the environmental pollution problem in the processing process is more serious.

[0004] Although the current traditional lithium battery recycling method solves the problem of recycling some metal elements to some extent, the production process is long, and the treatment cost of impurities such as aluminum, silicon and fluorine is high, and the separation is difficult. Most of the traditional recycling processes rely on physical sorting, chemical solvent leaching and other methods, although some useful metal elements can be extracted, but due to the unsatisfactory separation effect, the recovery rate of lithium salt lithium is usually only about 80%, far from the optimal effect of resource recovery. Especially in the face of high-impurity lithium battery positive electrode powder and battery positive electrode scrap, the traditional recycling method has great deficiencies in economy and environmental friendliness. Therefore, how to ensure efficient recovery while reducing the difficulty and cost of processing high-impurity components (such as aluminum, fluorine and silicon) has become a technical problem to be solved. SUMMARY

[0005] The present application aims to at least solve one of the above technical problems in the prior art. To this end, the present application provides a method for preparing battery-grade lithium carbonate from waste ternary lithium battery powder.

[0006] The first aspect of the present application provides a method for preparing battery-grade lithium carbonate from waste ternary lithium battery powder, comprising the following steps:

[0007] The waste ternary lithium battery powder is slurried to form a slurry, carbon dioxide is introduced for the first carbon washing, and after filtration, a filtrate A and a carbon washing residue A are obtained;

[0008] The filtrate A is subjected to deoiling and fluorine removal and first pyrolysis to obtain a crude lithium carbonate A, and the carbon washing residue A is subjected to first grinding, calcination, second grinding and second carbon washing, and after filtration, a filtrate B and a carbon washing residue B are obtained;

[0009] The carbon washing residue B is subjected to lithium extraction, filtration, fluorine and aluminum removal, concentration and precipitation after transformation treatment with calcium hydroxide to obtain a crude lithium carbonate B;

[0010] The filtrate B, the crude lithium carbonate B and the crude lithium carbonate A are mixed, and after carbonization, impurity removal, fine filtration, second pyrolysis, filtration and washing and drying, lithium carbonate is obtained.

[0011] For the comprehensive recovery of high-impurity components in the disassembly products of waste ternary lithium batteries, a new recycling method needs to be developed, which not only improves the recovery efficiency of valuable metals such as lithium, cobalt and nickel, but also effectively treats and separates impurities such as aluminum, silicon and fluorine generated during disassembly. The new recycling process should have the characteristics of high efficiency, low consumption and environmental friendliness, reduce energy consumption and harmful substance emissions in traditional recycling methods, improve resource utilization and reduce recycling costs. How to find a simple and efficient solution when faced with complex disassembly material components has become the main goal of current technical research and development. The solution to this problem will provide a new idea for the resource recovery of waste lithium batteries and promote the sustainable development of the battery recycling industry.

[0012] The present application directly adds water to the ternary battery to make slurry, then carbon wash is carried out by introducing carbon dioxide, most of the fluorine and silicon enter the solution, and then a part of the crude carbon can be prepared by deoiling and removing fluorine. After the carbon leaching and washing of the ternary battery powder, the powder is roasted in the presence of nitrogen (or carbon dioxide) gas, then ground and carbon washed by carbon dioxide, so that part of the lithium is converted into lithium bicarbonate and enters the solution. After the carbon washing, the residue is added into saturated calcium hydroxide water to convert lithium fluoride, lithium fluoroaluminate and the like in the residue into water-soluble lithium hydroxide. After the reaction is completed, sulfur dioxide gas is introduced to convert the lithium that has not been completely dissolved into lithium sulfate and dissolved in water for deep extraction. After the lithium extraction, the solution is defluorinated and concentrated, then carbon dioxide is introduced, sodium hydroxide is used to adjust the pH value, and the lithium is converted into crude lithium carbonate. The pyrolyzed crude lithium carbonate and the precipitated crude lithium carbonate are added into the secondary carbon washing solution, carbon dioxide is introduced to convert the lithium carbonate into lithium bicarbonate solution, then refined, pyrolyzed, filtered and washed, and dried to obtain battery-grade lithium carbonate. The present application has at least the following beneficial effects:

[0013] (1) Battery-grade lithium carbonate can be produced in a short process, and the production cost is reduced by fully utilizing the elements of the material itself.

[0014] (2) The raw material adaptability is stronger, and can be adapted to the production of most of the disassembled powder of the waste ternary lithium battery on the current market.

[0015] (3) The lithium yield is high, and the lithium yield can reach more than 92%.

[0016] The present application not only improves the resource recovery efficiency of waste lithium batteries, but also simplifies the process, improves the raw material adaptability, and optimizes the lithium recovery process, so as to achieve the goals of reducing cost and improving resource utilization, and has high economic and environmental value.

[0017] According to some embodiments of the present application, the method of slurry preparation comprises: adding 3-5 cubic meters of saturated calcium hydroxide solution per ton of waste ternary lithium battery powder, and reacting for 60-120 minutes.

[0018] According to some embodiments of the present application, the method of the first carbon washing comprises: introducing carbon dioxide into the slurry, adjusting the pH value to 6.5-7.4, and washing for 60-120 minutes.

[0019] According to some embodiments of the present application, the method of the second carbon washing comprises: adding 5-8 times the weight of the material of pure water, stirring and slurry preparation, then introducing carbon dioxide, adjusting the pH value to 7.5-7.8, and reacting for 60-90 minutes.

[0020] According to some embodiments of the present application, the method for removing fluorine and oil includes: adding 1-5 g of hydrogen peroxide to each liter of the filtrate A, after 30 min-60 min of reaction, adding calcium hydroxide in an amount of 2.5-3.5 times of the amount of fluorine in the filtrate A, continuing to react for 60 min-90 min, then passing carbon dioxide, adjusting the pH value to 7.5-7.8, and filtering.

[0021] According to some embodiments of the present application, the temperature of the roasting is 650℃-750℃; and / or, the time of the roasting is 120 min-150 min.

[0022] According to some embodiments of the present application, the method for transformation treatment includes: adding saturated calcium hydroxide solution to the carbon washing residue B, after stirring, heating to 90℃-95℃ for transformation reaction for 60 min-120 min, using calcium hydroxide to convert lithium fluoride into insoluble calcium fluoride residue and water-soluble lithium hydroxide.

[0023] According to some embodiments of the present application, the method for lithium extraction includes: after transformation treatment, the transformation liquid is continuously stirred and passed with sulfur dioxide gas while maintaining the temperature at 90℃-95℃, the pH value is adjusted to 5.5-6.5, the pH value is maintained for 60 min-120 min of reaction, after the reaction is completed, the pH value is adjusted to 10.5-12 using sodium hydroxide, and the reaction is continued for 60 min-120 min and then filtered.

[0024] According to some embodiments of the present application, the method for removing fluorine and aluminum includes: adding sulfuric acid to the filtrate after lithium extraction and filtration, adjusting the pH value to 6-7, adding a fluorine removal agent to remove residual fluorine ions, and removing aluminum in the form of aluminum hydroxide precipitation.

[0025] According to some embodiments of the present application, in the waste old ternary lithium battery powder, the content of aluminum is greater than 0.5 wt%, the content of fluorine is greater than 1.5 wt%, and the content of silicon is greater than 1.0 wt%. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a flow chart of a method for preparing battery-grade lithium carbonate from waste old ternary lithium battery powder. DETAILED DESCRIPTION

[0027] The following are specific embodiments of the present application, and the technical solutions of the present application are further described in conjunction with the embodiments, but the present application is not limited to these embodiments.

[0028] In the first aspect, some embodiments of the present application provide a method for preparing battery-grade lithium carbonate from waste old ternary lithium battery powder, and the flow is shown in Figure 1 The method includes the following steps:

[0029] The waste ternary lithium battery powder is slurried to form a slurry, carbon dioxide is introduced for the first carbon washing, and after filtration, a filtrate A and a carbon washing residue A are obtained;

[0030] The filtrate A is subjected to deoiling and fluorine removal and first pyrolysis to obtain a crude lithium carbonate A, and the carbon washing residue A is subjected to first grinding, roasting, second grinding, and second carbon washing, and after filtration, a filtrate B and a carbon washing residue B are obtained;

[0031] After the carbon washing residue B is added with calcium hydroxide for transformation treatment, lithium extraction, filtration, fluorine and aluminum removal, concentration, and precipitation, a crude lithium carbonate B is obtained, and between the fluorine and aluminum removal and concentration and after the precipitation, filtration can be further performed, after the fluorine and aluminum removal, filtration is performed to obtain a fluorine and aluminum residue, before the fluorine and aluminum removal, filtration is performed to obtain a nickel and cobalt residue, and after the precipitation, the mother liquor obtained can be returned to the lithium extraction step;

[0032] After the filtrate B, the crude lithium carbonate B, and the crude lithium carbonate A are mixed, carbonization impurity removal, precision filtration, second pyrolysis, filtration and washing, and drying are performed to obtain lithium carbonate, and the filtrate after the filtration and washing and the pyrolysis mother liquor after the first pyrolysis can be returned to the first carbon washing step.

[0033] It can be understood that for the comprehensive recovery of high-impurity components in the disassembled products of waste ternary lithium batteries, a new type of recovery method needs to be developed, which not only can improve the recovery efficiency of valuable metals such as lithium, cobalt, and nickel, but also can effectively treat and separate impurities such as aluminum, silicon, and fluorine generated during the disassembly process. The new recovery process should have the characteristics of high efficiency, low consumption, and environmental friendliness, reducing energy consumption and harmful substance emissions in traditional recovery methods, improving resource utilization rate and reducing recovery cost. How to find a simple and efficient solution when facing complex disassembled material components has become the main goal of current technical research and development. The solution to this problem will provide a new idea for the resource recovery of waste lithium batteries and promote the sustainable development of the battery recycling industry.

[0034] The present application directly adds water to the ternary battery, then carbon washes it with carbon dioxide, and most of the fluorine and silicon enters the solution. After deoiling and removing fluorine, a part of the crude carbon can be obtained. After the ternary battery powder is washed with carbon, it is roasted in the presence of nitrogen (or carbon dioxide) gas, then ground and carbon washed with carbon dioxide, and part of the lithium is converted into lithium bicarbonate and enters the solution. After carbon washing, the residue is added to saturated calcium hydroxide water to convert lithium fluoride, lithium fluoroaluminate and other substances in the residue into water-soluble lithium hydroxide. After the reaction is completed, sulfur dioxide gas is introduced to convert the undissolved lithium into lithium sulfate and dissolve it in water for deep extraction. After the lithium extraction solution is de-fluorinated and aluminum, it is concentrated and carbon dioxide is introduced, and the pH value is adjusted with sodium hydroxide to convert lithium into crude lithium carbonate. The pyrolyzed and precipitated crude lithium carbonate is added to the secondary carbon washing solution, carbon dioxide is introduced, lithium carbonate is converted into lithium bicarbonate solution, and after filtration, pyrolysis, filtration, and drying, battery-grade lithium carbonate is obtained. The present application has at least the following beneficial effects:

[0035] (1) Battery-grade lithium carbonate can be produced in a short process, and the elements of the material itself are fully utilized to reduce production costs.

[0036] Traditional methods for recycling waste lithium batteries usually require multiple complex steps, including high-temperature treatment, chemical reaction, acid washing, etc., and each step is accompanied by certain energy consumption and emissions. The present application can significantly simplify the entire process through carbon washing and deoiling and fluorine removal pretreatment steps.

[0037] Carbon washing: By reacting ternary battery powder with carbon dioxide, most of the fluorine, silicon and other impurities enter the solution, which can reduce the impurity content in the subsequent steps and reduce the amount of additional reagents required in the later chemical reaction.

[0038] Pyrolysis and secondary carbon washing: The pretreated material is further calcined and ground, and part of the lithium is converted into lithium bicarbonate through the carbonization process of carbon dioxide gas, which helps to improve the solubility of lithium and the efficiency of subsequent lithium extraction.

[0039] Calcium hydroxide transformation treatment: By converting fluorides and other impurities into water-soluble substances with calcium hydroxide, the dependence on acid or strong base in traditional methods is reduced, and environmental pollution is reduced.

[0040] The above technical innovation simplifies the process flow, eliminates the need for complex equipment and multiple process steps, thereby reducing production costs and energy consumption.

[0041] (2) It has stronger adaptability to raw materials and can adapt to most of the disassembled powder of waste ternary lithium batteries on the market.

[0042] The disassembled products of waste lithium batteries have complex and variable compositions, and the internal compositions of batteries produced by different manufacturers on the market may be different. Traditional recycling processes often have high requirements for the composition of raw materials and need to be adjusted according to different battery types. However, the process of the present application can adapt to different types of disassembled powders by designing multiple stages of physical and chemical reaction treatment:

[0043] Carbon washing process: Using carbon dioxide gas treatment can effectively remove fluorides, silicides and other impurities in waste batteries. No matter how the content of these impurities in the raw material changes, carbon washing can effectively remove them.

[0044] Flexible calcium hydroxide transformation treatment: According to different raw materials, the amount of calcium hydroxide can be flexibly adjusted to adapt to the processing needs of different disassembled products.

[0045] Adjustable pH value: In the lithium extraction process, the pH value is adjusted by sodium hydroxide, so that lithium can be converted into lithium carbonate to meet the needs of different raw materials. This makes the process have high adaptability to raw materials and can process most of the disassembled powders of waste ternary lithium batteries on the market.

[0046] (3) High lithium recovery rate, which can reach more than 92%.

[0047] Lithium recovery efficiency is one of the core indicators of battery recycling process, especially for waste ternary lithium batteries, the recovery rate of lithium directly affects the economic and environmental benefits. The present application realizes high-efficiency lithium recovery through a series of precise chemical reaction steps:

[0048] Carbon washing and roasting: The carbon washing process can effectively convert part of the lithium into lithium bicarbonate into the solution, reducing the loss of lithium. After roasting, part of the lithium can also be converted into water-soluble substances, further improving the recovery rate of lithium.

[0049] Lithium extraction and sulfur dioxide treatment: By passing sulfur dioxide gas treatment to the undissolved lithium, it is converted into lithium sulfate and enters the solution, providing more lithium source for the subsequent lithium extraction process.

[0050] Multiple carbon washing and precision filtration: Through secondary carbon washing liquid and precision filtration steps, more lithium can be extracted from solid materials, improving the recovery efficiency of lithium.

[0051] Final conversion of lithium into lithium carbonate: After fine filtration, pyrolysis and drying treatment, the final battery-grade lithium carbonate obtained has high purity, and the recovery rate of lithium is as high as 92% or more, significantly improving the utilization rate of resources.

[0052] In conclusion, the application not only improves the resource recycling efficiency of waste lithium batteries, but also reduces costs and improves resource utilization by simplifying the process, improving raw material adaptability, and optimizing the lithium recovery process, with high economic and environmental value.

[0053] In combination with the first aspect, in some embodiments of the application, the method of sizing includes adding 3-5 cubic meters of saturated calcium hydroxide solution per ton of waste ternary lithium battery powder, and reacting for 60-120 minutes.

[0054] In combination with the first aspect, in some embodiments of the application, the carbon washing is divided into two times, first carbon washing and second carbon washing.

[0055] In combination with the first aspect, in some embodiments of the application, the method of first carbon washing includes introducing carbon dioxide into the slurry, adjusting the pH to 6.5-7.4, and washing for 60-120 minutes.

[0056] After carbon washing, filtration, and defluorination, the filter residue is not dried and is ground before being sent to roasting. Carbon washing can convert fluorine in electrolyte and fluorine in binder into insoluble calcium fluoride into the slag, and can dissolve and remove silicon mixed during battery disassembly. Carbon dioxide can accelerate the dissolution of lithium ions in the negative electrode powder into the solution. The main reaction equations are as follows:

[0057] LiPF6+Ca(OH)2=LiOH+Ca(PF6)2↓

[0058] F - +Ca(OH)2=CaF2↓+OH -

[0059] LiPF6=LiF+PF5

[0060] 2PF5+8Ca(OH)2=Ca3(PO4)2↓+5CaF2↓+8H2O

[0061] PF5+H2O=POF3+HF

[0062] 2PF3+3Ca(OH)2=CaF2↓+Ca3(PO4)2↓+6H2O

[0063] SiO2+4HF=SiF4↑+2H2O

[0064] 2OH - +CO2=CO3 2- +H2O

[0065] LiOH+CO2=LiHCO3

[0066] Li+ + CO2 + CO3 2- + H2O = LiHCO3

[0067] Li + + CO2 + H2O = LiHCO3

[0068] The second carbon washing is carried out after the material is roasted, pure water is added to the material at room temperature, and stirring is started to slurry the material.

[0069] In combination with the first aspect, in some embodiments of the present application, the method of the second carbon washing comprises: adding 5-8 times the weight of the material of pure water, starting stirring to slurry the material, then passing in carbon dioxide, adjusting the pH to 7.5-7.8, and reacting for 60-90 minutes. The main reaction equation is as follows:

[0070] Li2CO3 + CO2 + H2O = 2LiHCO3

[0071] Li2O + 2CO2 + H2O = 2LiHCO3

[0072] In combination with the first aspect, in some embodiments of the present application, the method of the deoiling and defluorination comprises: adding 1-5 g of hydrogen peroxide to each liter of the filtrate A, after reacting for 30-60 minutes, adding calcium hydroxide in an amount of 2.5-3.5 times the amount of fluorine in the filtrate A, continuing to react for 60-90 minutes, then passing in carbon dioxide, adjusting the pH to 7.5-7.8, and filtering. The crude lithium carbonate can be obtained after pyrolysis of the filtrate, and the pyrolysis mother liquor can be returned to the first carbon washing. The hydrogen peroxide oxidizes the organic matter in the filtrate, which is removed from the filtrate by being adsorbed when the calcium hydroxide is added. The specific reaction equation is as follows:

[0073] F - + Ca(OH)2 = CaF2↓ + OH -

[0074] In combination with the first aspect, in some embodiments of the present application, after nitrogen or carbon dioxide gas is passed into the calcining furnace, the ground filter residue after the first carbon washing is added into the calcining furnace, and the temperature is raised to 650-750°C.

[0075] In combination with the first aspect, in some embodiments of the present application, the calcining time is 120-150 minutes.

[0076] After calcining, grinding is performed. In the atmosphere of nitrogen or carbon dioxide, the carbon in the wet battery powder can have a strong reducing effect under high temperature conditions. The specific reaction equation is as follows:

[0077] C + H2O = CO↑ + H2↑

[0078] CO + 2LiNiCoMnO2 = 2Ni + 2Co + 2MnO + Li2O + CO2↑

[0079] H2 + LiNiCoMnO2 = Ni + Co + MnO + LiOH + H2O

[0080] C + 2LiNiCoMnO2 = 2Ni + 2Co2 + MnO + Li2O + CO2↑

[0081] Li2O + CO2 = Li2CO3

[0082] In combination with the first aspect, in some embodiments of the present application, the method for transformation treatment comprises: adding saturated calcium hydroxide solution (3-5 m 3 / ton of filter residue) into the carbon washing residue B, and after starting stirring, heating to 90-95°C for 60-120 min of transformation reaction, using calcium hydroxide to convert lithium fluoride into insoluble calcium fluoride residue and water-soluble lithium hydroxide. The specific reaction equation is as follows:

[0083] Ca(OH)2 + 2LiF = CaF2↓ + 2LiOH

[0084] In combination with the first aspect, in some embodiments of the present application, the method for lithium extraction comprises: after transformation treatment, the transformation liquid is continuously stirred at 90-95°C and sulfur dioxide gas is introduced, the pH value is adjusted to 5.5-6.5, the pH value is maintained for 60-120 min of reaction, after the reaction is completed, sodium hydroxide is used to adjust the pH value to 10.5-12, and after 60-120 min of reaction, filtration is performed. Lithium is dissolved and extracted by using the reduction effect of sulfur dioxide and the deep layer degree of sulfuric acid and sulfuric acid produced after being dissolved in water, and then nickel, cobalt and manganese dissolved in the process are added into sodium hydroxide for precipitation, and the specific reaction equation is as follows:

[0085] SO2 + H2O = H2SO3

[0086] H2SO3 + 1 / 2O2 = H2SO4

[0087] Li2CO3 + H2SO4 = Li2SO4 + CO2 + H2O

[0088] H2SO3 + MnO = MnSO4 + H2↑

[0089] H2SO4 + Ni = NiSO4 + H2↑

[0090] H2SO4 + Co = CoSO4 + H2↑

[0091] MnSO4 + NaOH = Mn(OH)2↓

[0092] NiSO4 + NaOH = Ni(OH)2↓

[0093] CoSO4 + NaOH = Co(OH)2↓

[0094] In combination with the first aspect, in some embodiments of the present application, the method for removing fluorine and aluminum comprises: adding sulfuric acid to the filtrate after lithium extraction and filtration, adjusting the pH value to 6-7, and then adding a fluorine removal agent to remove residual fluorine ions, while removing aluminum in the form of aluminum hydroxide precipitation. After removing fluorine and aluminum, filtration is performed, and after the filtrate is concentrated 5-6 times, sodium carbonate is added for precipitation reaction. After filtration, crude lithium carbonate is obtained, and the filtrate can be returned to the lithium extraction process.

[0095] In combination with the first aspect, in some embodiments of the present application, the content of aluminum in the waste and old ternary lithium battery powder is greater than 0.5wt%, the content of fluorine is greater than 1.5wt%, and the content of silicon is greater than 1.0wt%.

[0096] In combination with the first aspect, in some embodiments of the present application, regarding carbonization impurity removal, the two obtained crude lithium carbonate is added to the second carbon washing filtrate, and when the carbon washing filtrate is insufficient, pure water can be supplemented, stirring is started, and carbon dioxide is introduced at room temperature, the pH value is controlled at 7.5-7.8, the reaction is carried out for 60-120 minutes, and after the reaction is completed, precision filtration is performed. In water, the main component lithium carbonate in the crude lithium carbonate is dissolved by carbon dioxide, while the impurities cannot be dissolved, thereby achieving the removal of impurities. The main reaction equation is as follows:

[0097] Li2CO3 + CO2 + H2O = 2LiHCO3

[0098] In combination with the first aspect, in some embodiments of the present application, regarding pyrolysis, the carbonization impurity removal liquid after precision filtration is stirred, heated to 90-100℃, and pyrolysis is performed, and after the reaction is carried out for 60-120 minutes, filtration is performed to obtain lithium carbonate, and the mother liquor is washed off from the surface of the lithium carbonate, and the mother liquor and the washing water are returned to the first carbon washing cycle for reuse. The filter residue is dried and packaged to obtain battery-grade lithium carbonate. The pyrolysis reaction equation is as follows:

[0099] 2LiHCO3 = Li2CO3 + CO2↑ + H2O

[0100] The concept and technical effects of the present application will be described clearly and completely in combination with the embodiments below, so as to fully understand the purpose, features and effects of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0101] In the description of the application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples.

[0102] Unless otherwise specified, "room temperature" in the present application means 25℃±5℃.

[0103] Unless otherwise specified, "about" in the present application means that the allowable error is within ±2%.

[0104] Unless otherwise specified, the specific conditions in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be purchased on the market.

[0105] In each embodiment, the fluorine agent is purchased from Hunan Aisenik Environmental Technology Co., Ltd.

[0106] Example 1

[0107] The analysis and detection results of the waste ternary battery powder are as follows:

[0108] Li F C Ni Co Mn Si Al 4.35％ 3.05％ 16.82％ 20.43％ 9.58％ 10.54％ 1.61％ 5.26％

[0109] Take 2000g of the above waste ternary lithium battery powder and place it in a reactor, add 10L of saturated calcium hydroxide, and start stirring for 120 minutes. After the reaction is completed, carbon dioxide gas is introduced to adjust the pH value to 6.5, and the process is stabilized at pH 6.5 for 120 minutes. After the reaction is completed, filter to obtain 9500mL of filtrate A, and the analysis results of the filtrate are as follows:

[0110] Li F Si Al 2.74 g / L 0.15 g / L 0.001 g / L 0.0008 g / L

[0111] Take the above filtrate A and place it in a reactor, start stirring, add 47.5g of hydrogen peroxide, and react for 60 minutes. After the reaction is completed, add 4.5g of calcium hydroxide and continue to react for 90 minutes. After the reaction is completed, carbon dioxide gas is introduced to adjust the pH value to 7.8, and after the pH value is stabilized, filter. The filter residue is dried and weighed as 63.3g, and the residual lithium in the residue is 0.091%. The filtrate is heated to 100℃ while stirring, and the temperature is maintained for 120 minutes. After the reaction is completed, filter, and the filter residue is crude lithium carbonate A.

[0112] The first step of the filter residue (i.e. carbon washing residue A) was ground and put into a calcining furnace. Nitrogen was pre-purified in the furnace and the temperature was raised to 750°C and maintained for 150 minutes. After the reaction was completed, the calcined material was cooled and weighed, 1483g. The calcined material was ground.

[0113] The ground material was placed in a reactor, 11.5L of pure water was added, stirring was started, and then carbon dioxide gas was introduced to adjust the pH value to 7.8. The pH value was stabilized for 90 minutes. After the reaction was completed, the filtrate B was obtained by filtration, 11470mL, which was ready for use. The filter residue (i.e. carbon washing residue B) was dried and weighed, 1386g.

[0114] The filter residue was taken and added to a reactor, 6900mL of saturated calcium hydroxide water was added, the temperature was raised to 95°C, and the reaction was maintained for 120 minutes. After the reaction was completed, the heating was stopped and the pH value was adjusted to 6.5 by introducing sulfur dioxide gas. The pH value was maintained for 120 minutes. After the reaction was completed, sodium hydroxide was added to adjust the pH value to 12, and the pH value was maintained for 120 minutes. After the reaction was completed, the filter residue was obtained by filtration, 1335g, and the residual lithium was measured to be 0.36%. The filtrate was adjusted to a pH value of 7 by adding sulfuric acid, and a fluoride removal agent was added for fluoride removal. After filtration, the filtrate was obtained, 6900mL, and the fluoride removal residue was 22.6g. The residual lithium was measured to be 0.088%. After the fluoride removal, the filtrate was concentrated to 1150mL, and sodium carbonate was added for precipitation. After filtration, the filter residue was the crude lithium carbonate B.

[0115] The two obtained crude lithium carbonate was added to the second carbon washing filtrate (i.e. filtrate B), stirring was started, and carbon dioxide gas was introduced at room temperature to adjust the pH value to 7.8. The pH value was stabilized at 7.8 for 120 minutes. After the reaction was completed, the filter residue was obtained by precise filtration through two layers of qualitative filter paper, 23.85g, and the residual lithium was measured to be 0.13%. The filtrate was added to a reactor, stirring was started, and the temperature was raised to 100°C. After the reaction was maintained for 120 minutes, the filter residue was obtained by filtration, and the filter residue was washed in the filter. After drying, the filter residue was the battery-grade lithium carbonate. The sample analysis results are as follows:

[0116] Li2CO3 Li Pb Cu Fe Al Mn Mg Ca 99.44 18.71 0.0002 0.0001 0.0002 0.0005 0.0001 0.0023 0.0031 Na K Si Cl SO4 2- ]]> Ni Co D50 Hydrochloric acid insolubles 0.0018 0.0013 0.002 0.003 0.015 0.0 0.001 9.38 0.0034

[0117] Because the mother liquor and washing water can be recycled, the yield only considers the residual lithium loss in the discharged residue. Therefore, the yield is as follows:

[0118] 1-[(63.3×0.091%)-(1335×0.36%)-(22.6×0.088%)-(23.85×0.13%)] / (2000×4.35%)=94.35%。

[0119] Example 2

[0120] The analysis and detection results of the waste ternary battery powder are as follows:

[0121] Li F C Ni Co Mn Si Al 5.08％ 2.38％ 15.11％ 21.03％ 10.12％ 12.36％ 1.01％ 4.08％

[0122] Take 2000g of the above-mentioned waste ternary lithium battery powder and place it in a reactor, add 6L of saturated calcium hydroxide, and start stirring for 60 minutes. After the reaction is complete, adjust the pH value to 7.4 by passing in carbon dioxide gas, and stabilize the pH value at 7.4 for 60 minutes using carbon dioxide gas. After the reaction is complete, filter to obtain 5500mL of filtrate A, and the analysis results of the filtrate are as follows:

[0123] Li F Si Al 4.54 g / L 0.21 g / L 0.003 g / L 0.0005 g / L

[0124] Take the above-mentioned filtrate A and place it in a reactor, start stirring, add 5.5g of hydrogen peroxide, and react for 30 minutes. After the reaction is complete, add 2.9g of calcium hydroxide and continue to react for 60 minutes. After the reaction is complete, pass in carbon dioxide gas to adjust the pH value to 7.5, and filter after the pH value is stabilized. The filter residue is dried and weighed to be 21.3g, and the residual lithium in the residue is 0.15%. The filtrate is heated to 90°C while stirring, and the temperature is maintained for 60 minutes. After the reaction is complete, filter, and the filter residue is crude lithium carbonate A.

[0125] Grind the filter residue of the first step (i.e., carbon washing residue A) and place it in a forging furnace. The furnace has been pre-filled with nitrogen, and the temperature is raised to 650°C, and the reaction is maintained for 120 minutes. After the reaction is complete, cool and weigh the forged material to be 1512g, and grind the forged material.

[0126] Place the above-mentioned ground material in a reactor, add 7.7L of pure water, start stirring to make a slurry, then pass in carbon dioxide gas to adjust the pH value to 7.5, and stabilize the pH value for 90 minutes. After the reaction is complete, filter to obtain 7450mL of filtrate B for standby use, and the filter residue (i.e., carbon washing residue B) is dried and weighed to be 1439g.

[0127] Take the above-mentioned filter residue and add it to a reactor, add 4400mL of saturated calcium hydroxide water, and raise the temperature to 95°C, and react for 60 minutes. After the reaction is complete, stop heating and maintain the temperature, pass in sulfur dioxide gas to adjust the pH value to 5.5, and maintain the pH value for 120 minutes. After the reaction is complete, add sodium hydroxide to adjust the pH value to 10.5, and maintain the pH value for 60 minutes. After the reaction is complete, filter, and the filter residue is dried and weighed to be 1267g, and the residual lithium is measured to be 0.33%. After adjusting the pH value of the filtrate to 6 using sulfuric acid, add a fluoride removal agent to remove fluoride, filter to obtain 4400mL of filtrate and 18.9g of fluoride removal residue, and the residual lithium is measured to be 0.053%. Concentrate the fluoride removal filtrate to 1150mL, add sodium carbonate to precipitate, and filter to obtain crude lithium carbonate B.

[0128] The two obtained crude lithium carbonate was added to the second carbon washing filtrate (i.e. filtrate B), 5500 mL of pure water was added (due to the solubility of lithium bicarbonate, adding pure water is more conducive to the dissolution of lithium carbonate), stirring was started, carbon dioxide gas was introduced at room temperature, the pH value was adjusted to 7.5, and the pH value was stabilized at 7.5 for 60 minutes. After the reaction was completed, the filtrate was filtered through two layers of qualitative filter paper, and 18.33 g of residue was obtained, with a residual lithium content of 0.16%. The filtrate was added to the reactor, stirring was started, and the temperature was raised to 100°C, and the reaction was carried out for 120 minutes. The filtrate was filtered, and the residue was washed in the filter. The residue was dried to obtain battery-grade lithium carbonate. The sample analysis results are as follows: unit: %

[0129] Li2CO3 Li Pb Cu Fe Al Mn Mg Ca 99.53 18.75 0.0002 0.0001 0.0002 0.0005 0.0001 0.0011 0.00171 Na K Si Cl SO4 2- ]]> Ni Co D50 Hydrochloric acid insolubles 0.0012 0.0008 0.0005 0.001 0.013 0.001 0.001 8.22 0.0022

[0130] Because the mother liquor and washing water can be recycled, the yield only considers the loss of residual lithium in the discharged residue, so the yield is as follows:

[0131] 1-[(21.3×0.15%)-(1267×0.33%)-(18.9×0.053%)-(18.33×0.16%)] / (2000×5.08%)=95.82%。

[0132] Example 3

[0133] The analysis results of the waste ternary battery powder are as follows:

[0134] Li F C Ni Co Mn Si Al 3.63％ 2.88％ 19.74％ 17.11％ 10.09％ 9.38％ 2.28％ 3.75％

[0135] Take 2500g of the above waste ternary lithium battery powder and place it in a reactor, add 7.5L of saturated calcium hydroxide, start stirring and react for 120 minutes. After the reaction is completed, introduce carbon dioxide gas to adjust the pH value to 6.5, and use carbon dioxide gas to stabilize the pH value at 6.5 for 120 minutes. After the reaction is completed, filter the filtrate A 6900mL, and the analysis results of the filtrate are as follows:

[0136] Li F Si Al 3.21 g / L 0.28 g / L 0.003 g / L 0.0005 g / L

[0137] Take the above filtrate A and place it in a reactor, start stirring, add 21.7g of hydrogen peroxide, and react for 60 minutes. After the reaction is completed, add 6.5g of calcium hydroxide and continue to react for 90 minutes. After the reaction is completed, introduce carbon dioxide gas to adjust the pH value to 7.8, and filter after the pH value is stabilized. The residue is dried to weigh 41.8g, and the residual lithium in the residue is 0.11%. The filtrate is stirred and heated to 95°C, and the reaction is carried out for 120 minutes. After the reaction is completed, the filtrate is filtered, and the residue is crude lithium carbonate A.

[0138] The first step of the filter residue (i.e. carbon washing residue A) was ground and put into a calcining furnace. The furnace was pre-filled with nitrogen and heated to 700°C and kept for 150 minutes. After the reaction was completed, the calcined material was cooled and weighed to be 2025g. The calcined material was ground.

[0139] The ground material was put into a reactor and 12.5L of pure water was added. The stirring was started and carbon dioxide gas was introduced to adjust the pH value to 7.7. The pH value was kept stable for 90 minutes. After the reaction was completed, the filtrate B was obtained by filtration. The weight of the filter residue (i.e. carbon washing residue B) was 1782g after drying.

[0140] The filter residue was put into a reactor and 6500mL of saturated calcium hydroxide water was added. The temperature was raised to 92°C and the reaction was kept for 120 minutes. After the reaction was completed, the heating was stopped and sulfur dioxide gas was introduced to adjust the pH value to 6.0. The pH value was kept stable for 120 minutes. After the reaction was completed, sodium hydroxide was added to adjust the pH value to 11 and the pH value was kept stable for 120 minutes. The filter residue was obtained by filtration after the reaction was completed. The weight of the filter residue was 1711g after drying. The residual lithium was 0.38%. The pH value of the filtrate was adjusted to 6.5 using sulfuric acid. Defluorination agent was added to remove fluorine. The filtrate was obtained by filtration. The weight of the defluorination residue was 30.5g. The residual lithium was 0.063%. The filtrate was concentrated to 1100mL after defluorination. Sodium carbonate was added to precipitate and the filter residue was the crude lithium carbonate B.

[0141] The two crude lithium carbonates were added to the second carbon washing filtrate (i.e. filtrate B). The stirring was started and carbon dioxide gas was introduced to adjust the pH value to 7.7 at room temperature. The pH value was kept stable for 120 minutes. The filter residue was obtained by precise filtration using two layers of qualitative filter paper after the reaction was completed. The weight of the filter residue was 19.43g. The residual lithium was 0.18%. The filtrate was put into a reactor and the stirring was started. The temperature was raised to 95°C and the reaction was kept for 120 minutes. The filter residue was washed in the filter. The filter residue was dried to obtain the battery grade lithium carbonate. The sampling analysis results are as follows:

[0142] Li2CO3 Li Pb Cu Fe Al Mn Mg Ca 99.28 18.69 0.0003 0.0002 0.0005 0.0008 0.0005 0.0027 0.0020 Na K Si Cl SO4 2- ]]> Ni Co D50 Hydrochloric acid insolubles 0.0011 0.0017 0.0016 0.0024 0.013 0.002 0.002 10.03 0.0055

[0143] Because the mother liquor and washing water can be recycled, the yield only considers the residual lithium loss in the discharged residue. Therefore, the yield is as follows:

[0144] 1-[(41.8x0.11%)-(1711x0.38%)-(30.5x0.063%)-(193.43x0.18%)] / (2500x3.635%)=92.34%。

[0145] Example 4

[0146] The analysis results of the waste ternary battery powder are as follows:

[0147] Li F C Ni Co Mn Si Al 2.13％ 4.11％ 30.46％ 11.23％ 6.77％ 10.09％ 2.95％ 3.87％

[0148] Take 3000g of the above-mentioned waste ternary lithium battery powder into a reactor, add 14L of saturated calcium hydroxide, and start stirring for 120 minutes. After the reaction is completed, carbon dioxide gas is introduced to adjust the pH value to 7.0, and the pH value is stabilized at 7.0 for 120 minutes. After the reaction is completed, filtration is performed, and 13280mL of filtrate A is obtained. The analysis results of the filtrate are as follows:

[0149] Li F Si Al 4.54 g / L 0.28 g / L 0.0007 g / L 0.001 g / L

[0150] Take the above-mentioned filtrate A into a reactor, start stirring, add 53.5g of hydrogen peroxide, and react for 60 minutes. After the reaction is completed, 11.2g of calcium hydroxide is added, and the reaction is continued for 90 minutes. After the reaction is completed, carbon dioxide gas is introduced to adjust the pH value to 7.6, and filtration is performed after the pH value is stabilized. The dried residue is weighed as 71.5g, and the residual lithium in the residue is 0.11%. The filtrate is heated to 95°C while stirring, and the temperature is maintained for 120 minutes. After the reaction is completed, filtration is performed, and the residue is the crude lithium carbonate A.

[0151] After the first step residue (i.e. carbon washing residue A) is ground, it is put into a sintering furnace. Nitrogen gas has been pre-introduced into the furnace, and the temperature is raised to 680°C, and the reaction is maintained for 150 minutes. After the reaction is completed, the sintered material is cooled and weighed as 2280g. The sintered material is ground.

[0152] The above-mentioned ground material is placed into a reactor, 11.5L of pure water is added, stirring is started, and then carbon dioxide gas is introduced to adjust the pH value to 7.6, and the pH value is stabilized for 90 minutes. After the reaction is completed, filtration is performed, and 11420mL of filtrate B is obtained for standby use, and the residue (i.e. carbon washing residue B) is dried and weighed as 2178g.

[0153] The above-mentioned residue is taken into a reactor, 8500mL of saturated calcium hydroxide water is added, the temperature is raised to 95°C, and the reaction is maintained for 120 minutes. After the reaction is completed, the heating is stopped, sulfur dioxide gas is introduced to adjust the pH value to 6.0, and the pH value is maintained for 120 minutes. After the reaction is completed, sodium hydroxide is added to adjust the pH value to 10.8, and the pH value is maintained for 120 minutes. After the reaction is completed, filtration is performed, and the residue is dried and weighed as 2112g, and the residual lithium is measured as 0.22%. After the pH value of the filtrate is adjusted to 6 with sulfuric acid, a fluoride removal agent is added for fluoride removal, and after filtration, 8500mL of filtrate is obtained, and 30.1g of fluoride removal residue is obtained, and the residual lithium is measured as 0.11%. After the filtrate after fluoride removal is concentrated to 1700mL, sodium carbonate is added for precipitation, and filtration is performed, and the residue is the crude lithium carbonate B.

[0154] The two obtained crude lithium carbonate was added to the second carbon washing filtrate (i.e. filtrate B), stirring was started, carbon dioxide gas was introduced at room temperature, the pH value was adjusted to 7.8, and the pH value was stabilized at 7.8 for 120 minutes. After the reaction was completed, the filtrate was precisely filtered through two layers of qualitative filter paper, and 40.15 g of filter residue was obtained, and the residual lithium was 0.16%. The filtrate was added to the reactor, stirring was started, and the temperature was raised to 95°C, and the reaction was carried out for 120 minutes, and then the filter residue was washed in the filter. The filter residue was dried to obtain battery-grade lithium carbonate, and the sample analysis results were as follows: unit: %

[0155] Li2CO3 Li Pb Cu Fe Al Mn Mg Ca 99.22 18.65 0.0003 0.0002 0.0009 0.0007 0.0008 0.0025 0.0016 Na K Si Cl SO4 2- ]]> Ni Co D50 Hydrochloric acid insolubles 0.0026 0.0022 0.003 0.002 0.018 0.002 0.001 10.58 0.0040

[0156] Because the mother liquor and washing water can be recycled, the yield only considers the residual lithium loss in the discharged residue, so the yield is as follows:

[0157] 1-[(71.5x0.11%)-(2112x0.22%)-(30.1x0.11%)-(40.15x0.16%)] / (3000x2.13%) = 92.50%.

[0158] The above has made a detailed description of the present application in combination with the examples, but the present application is not limited to the above examples, and various changes can be made within the knowledge possessed by those skilled in the art without departing from the purpose of the present application.

Claims

1. A method for preparing battery grade lithium carbonate from spent ternary lithium battery powder, characterized in that, The method comprises the following steps: The waste ternary lithium battery powder is slurried to form a slurry, carbon dioxide is introduced for first carbon washing, and the slurry is filtered to obtain filtrate A and carbon washing residue A; The filtrate A is subjected to deoiling and fluorine removal and first pyrolysis to obtain crude lithium carbonate A, and the carbon washing residue A is subjected to first grinding, roasting, second grinding, and second carbon washing, and is filtered to obtain filtrate B and carbon washing residue B; The carbon washing residue B is subjected to lithium extraction, filtration, fluorine and aluminum removal, concentration, and precipitation after being subjected to transformation treatment by adding calcium hydroxide, to obtain crude lithium carbonate B; The filtrate B, the crude lithium carbonate B, and the crude lithium carbonate A are mixed, and are subjected to carbonization and impurity removal, precision filtration, second pyrolysis, filtration and washing, and drying to obtain lithium carbonate.

2. The method of claim 1, wherein, The slurry method comprises: adding 3-5 cubic meters of saturated calcium hydroxide solution per ton of the waste ternary lithium battery powder, and reacting for 60-120 minutes.

3. The method of claim 1, wherein, The first carbon washing method comprises: introducing carbon dioxide into the slurry, adjusting the pH to 6.5-7.4, and washing for 60-120 minutes.

4. The method of claim 1, wherein, The second carbon washing method comprises: adding 5-8 times the weight of the material of pure water, stirring the slurry, then introducing carbon dioxide, adjusting the pH to 7.5-7.8, and reacting for 60-90 minutes.

5. The method of claim 1, wherein, The deoiling and fluorine removal method comprises: adding 1-5 g of hydrogen peroxide to each liter of the filtrate A, reacting for 30-60 minutes, then adding calcium hydroxide in an amount of 2.5-3.5 times the amount of fluorine in the filtrate A, continuing to react for 60-90 minutes, then introducing carbon dioxide, adjusting the pH to 7.5-7.8, and filtering.

6. The method of claim 1, wherein, The roasting temperature is 650-750 DEG C; and / or, the roasting time is 120-150 minutes.

7. The method of claim 1, wherein, The transformation treatment method comprises: adding saturated calcium hydroxide solution to the carbon washing residue B, stirring, then heating to 90-95 DEG C for transformation reaction for 60-120 minutes, and converting lithium fluoride into insoluble calcium fluoride residue and water-soluble lithium hydroxide by using calcium hydroxide.

8. The method of claim 1, wherein, The lithium extraction method comprises: continuing to stir the transformation liquid after the transformation treatment at a temperature of 90-95 DEG C, introducing sulfur dioxide gas, adjusting the pH to 5.5-6.5, maintaining the pH for 60-120 minutes, adjusting the pH to 10.5-12 by using sodium hydroxide after the reaction is completed, and filtering after reacting for 60-120 minutes.

9. The method of claim 1, wherein, The fluorine and aluminum removal method comprises: adding sulfuric acid to the filtrate after lithium extraction and filtration, adjusting the pH to 6-7, adding a fluorine removal agent to remove residual fluorine ions, and removing aluminum in the form of aluminum hydroxide precipitate.

10. The method of claim 1, wherein, The aluminum content in the waste ternary lithium battery powder is greater than 0.5 wt%, the fluorine content is greater than 1.5 wt%, and the silicon content is greater than 1.0 wt%.

Images