Method for preparing battery-grade lithium hydroxide monohydrate through lithium hydroxide mother liquor multiple crystallization
Through multiple crystallization processes and the method of recycling filtrate, the impurity control problem in the production of single water lithium hydroxide is solved, and the preparation of high-purity lithium hydroxide is realized, meeting the requirements of lithium batteries for high purity.
Patent Information
- Application Number
- CN202411325640.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-23
- Publication Date
- 2024-12-27
AI Technical Summary
In the production of monowater lithium hydroxide, the prior art is difficult to effectively control the impurity content and cannot meet the requirements of lithium batteries for high purity.
Multiple crystallization processes are adopted, and the separation is separated by evaporation concentration and suction filtration, combined with the filtrate to improve the purity of lithium hydroxide, including multi-step evaporation and cooling treatment, using deionized water and water bath rotary evaporation method, and controlling process parameters such as temperature, Pressure and stirring speed, triple crystallization is performed to achieve high purity.
It significantly improves the purity of lithium hydroxide, can meet the requirements of more stringent process scenarios, and ensures that the product meets the high purity standards of battery-grade single-water lithium hydroxide.
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Figure CN119191318A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of lithium hydroxide purification and preparation, and specifically relates to a battery-grade lithium hydroxide monohydrate purification and preparation process. Background Art
[0002] With the continuous development of the new energy industry, the demand for lithium hydroxide monohydrate as an important raw material for lithium batteries is increasing. At the same time, the quality requirements of various material and battery manufacturers for lithium hydroxide monohydrate are getting higher and higher. In the production of lithium hydroxide monohydrate, controlling the content of its impurities is an important step in preparing battery-grade lithium hydroxide monohydrate. Therefore, a battery-grade lithium hydroxide purification process that can solve the above problems is needed. Summary of the invention
[0003] The purpose of the present invention is to provide a method for preparing and purifying battery-grade lithium hydroxide monohydrate, thereby effectively improving the product purity and output of lithium hydroxide monohydrate.
[0004] The present invention provides the following technical solutions:
[0005] A method for preparing battery-grade lithium hydroxide monohydrate from lithium hydroxide mother liquor comprises the following steps:
[0006] Step 1: Add lithium hydroxide raw material and solvent in corresponding proportions into a container and mix them evenly to obtain a mixed solution;
[0007] Step 2: Evaporate and concentrate the mixed solution in step 1 to obtain a solid solution mixture I of a certain proportion, and separate by suction filtration to obtain a crystalline product A and a filtrate a;
[0008] Step 3: dissolving the crystalline product A obtained in step 2 with deionized water, evaporating and concentrating to obtain a solid solution mixture II of a certain proportion, and filtering and separating to obtain the crystalline product B and the filtrate b;
[0009] Step 4: dissolving the crystalline product B obtained in step 3, evaporating and concentrating to obtain a certain proportion of solid solution mixture III, and filtering and separating to obtain crystalline product C and filtrate c;
[0010] In a possible design, experiment 4 should also include the recovery and purification of part of the filtrate:
[0011] Step 5: reflux the filtrate b obtained in step 3 and the filtrate c obtained in step 4 to the evaporation device in step 2 for recycling, thereby increasing the yield of lithium hydroxide;
[0012] Preferably, in step 1, the mass ratio of the solvent deionized water to industrial lithium hydroxide is (5-10):1, the stirring speed is 300-700 r / min, and the temperature is 50-60°C.
[0013] Preferably, a water bath rotary evaporation method is used in the entire preparation process, and a round-bottom flask is selected as the container to increase the contact area.
[0014] Preferably, the mass ratio of the crystallized product to the filtrate in the solid solution mixture of step 2 is 1:(1.5-2).
[0015] Preferably, the mass ratio of the crystallized product to the filtrate in the solid solution mixture of step three is 1:(1-1.5).
[0016] Preferably, the mass ratio of the crystallized product to the filtrate mother liquor in the solid solution mixture of step 4 is 1:(0.5-1).
[0017] Preferably, the water bath temperature of the rotary evaporator is 70-80°C.
[0018] Preferably, the rotation speed of the rotary evaporator is 40-80 r / min.
[0019] Preferably, the absolute pressure inside the rotary evaporator is maintained at about 40-100 hPa.
[0020] Preferably, the high-temperature solid solution mixture should be cooled to improve the crystallization yield, wherein the cooling operation uses oil bath cooling, the temperature of the oil bath pot is controlled at 20-30° C., and the stirring speed is 200-500 r / min.
[0021] Preferably, the separation operation of the evaporated crystallized solid solution mixture is performed by suction filtration.
[0022] Preferably, the crystal product obtained by filtration should be dried. The drying operation can be carried out by vacuum drying operation, with a temperature of 70-100° C., an oven pressure of 10-30 Pa, and a drying time of 12-24 h.
[0023] The technology of the present invention achieves the purity requirement through a triple crystallization process. If other technicians can perform purity analysis on the obtained crystalline product in actual operation, they can judge whether it is necessary to add a crystallization step.
[0024] Compared with the prior art, the technology provided by the present invention can further improve the purity of lithium hydroxide when the impurities contained in the raw materials are already very low. Through the simplest physical crystallization method and using appropriate process parameters, a higher quality lithium hydroxide crystalline product can be prepared, which can be applicable to more stringent process scenarios. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 The present invention is a lithium hydroxide purification process flow chart.
[0026] Figure 2 This is a diagram of the third-stage lithium hydroxide crystallization product. Specific implementation methods
[0027] See also Figure 1 The present invention aims to further purify the already high-purity lithium hydroxide raw material to obtain a higher purity lithium hydroxide product to meet more stringent process requirements. In the present invention, the number of multiple crystallizations depends on the purity requirements for lithium hydroxide in actual production. When the crystallization product meets the purity requirements, it can be stopped. Figure 2 The third-stage lithium hydroxide crystal product diagram is shown; if the purity requirement is not met, further steps may be added. The process of the present invention is described below through specific examples.
[0028] Example 1
[0029] A method for preparing battery-grade lithium hydroxide monohydrate by multiple crystallization of lithium hydroxide mother liquor, specifically comprising the following steps:
[0030] (1) Using a 1000 ml round-bottom flask as a container, weigh 70 g of lithium hydroxide raw material, add 400 ml of deionized water to the raw material, heat the oil bath to 55° C., and stir continuously until the lithium hydroxide raw material is completely dissolved to obtain solution A.
[0031] (2) The homogeneous solution A is placed in a round-bottom flask, and the raw material is pretreated using a rotary evaporator to obtain a uniformly mixed lithium hydroxide raw material.
[0032] (3) Dissolving the lithium hydroxide raw material in step (2) again, subjecting the obtained lithium hydroxide raw material to a first evaporation crystallization, heating the round-bottom flask in a water bath at 70° C., rotating the flask at 80 rpm, and evacuating the entire device at the same time, maintaining the absolute pressure of the system at approximately 100 hPa.
[0033] (4) Rotary evaporation of the lithium hydroxide solution for about 40 minutes, when the mass ratio of the crystallized product to the concentrated mother liquor in the solid solution mixture is 1:1.5, the rotary evaporation is stopped.
[0034] (5) The obtained solid solution mixture was cooled to 30° C. in an oil bath, and the crystallized product A and the filtrate a were separated by suction filtration.
[0035] (6) The crystalline product A was placed in a vacuum oven at 70°C for 12 hours to obtain a dry product.
[0036] (7) Weigh 35 g of the primary crystal product A, use a 500 ml round-bottom flask as a container, add 200 ml of deionized water to the raw material, raise the oil bath temperature to 55° C., and stir continuously until the lithium hydroxide raw material is completely dissolved to obtain solution B.
[0037] (8) Solution B was subjected to secondary evaporation crystallization. The round-bottom flask was kept heated in a water bath at 75° C. The flask rotation was set at 80 r / min. At the same time, the entire device was evacuated and the absolute pressure of the system was maintained at around 80 hPa.
[0038] (9) The lithium hydroxide solution was rotary evaporated for about 30 minutes. When the mass ratio of the crystallized product to the concentrated mother liquor in the solid solution mixture was 1:1, the rotary evaporation was stopped.
[0039] The subsequent treatment is the same as that of the primary crystallization product of lithium hydroxide, and the secondary crystallization product B and the filtrate b are obtained after cooling, filtration and drying.
[0040] (10) Weigh 20 g of the primary crystal product B, use a 250 ml round-bottom flask as a container, add 150 ml of deionized water to the raw material, raise the oil bath temperature to 55 °C, and stir continuously until the lithium hydroxide raw material is completely dissolved to obtain solution C.
[0041] (11) Solution C was subjected to secondary evaporation crystallization. The round-bottom flask was kept heated in a water bath at 75°C. The flask rotation was set at 80 r / min. At the same time, the entire device was evacuated and the absolute pressure of the system was maintained at approximately 40 hPa.
[0042] (12) The lithium hydroxide solution was rotary evaporated for about 20 min. When the mass ratio of the crystallized product to the concentrated mother liquor in the solid solution mixture was 1:0.5, the rotary evaporation was stopped.
[0043] (13) The subsequent treatment of the primary crystal product of lithium hydroxide is the same as that of the secondary crystal product of lithium hydroxide, and after cooling, filtration and drying, a tertiary crystal product C and a filtrate c are obtained.
[0044] (14) The filtrate b and the filtrate c are retained and added to the lithium hydroxide solution for the next multiple evaporation and crystallization operation to carry out a cyclic evaporation and crystallization operation.
[0045] Example 2
[0046] A method for preparing battery-grade lithium hydroxide monohydrate by multiple crystallization of lithium hydroxide mother liquor, specifically comprising the following steps:
[0047] (1) Using a 1000 ml round-bottom flask as a container, weigh 70 g of lithium hydroxide raw material, add 400 ml of deionized water to the raw material, heat the oil bath to 55° C., and stir continuously until the lithium hydroxide raw material is completely dissolved to obtain solution A.
[0048] (2) The homogeneous solution A is placed in a round-bottom flask, and the raw material is pretreated using a rotary evaporator to obtain a uniformly mixed lithium hydroxide raw material.
[0049] (3) Dissolving the lithium hydroxide raw material in step (2) again, subjecting the obtained lithium hydroxide raw material to a first evaporation crystallization, heating the round-bottom flask in a water bath at 65° C., rotating the flask at 80 rpm, and evacuating the entire device at the same time, maintaining the absolute pressure of the system at approximately 100 hPa.
[0050] (4) Rotary evaporation of the lithium hydroxide solution for about 40 minutes, when the mass ratio of the crystallized product to the concentrated mother liquor in the solid solution mixture is 1:2, the rotary evaporation is stopped.
[0051] (5) The obtained solid solution mixture was cooled to 30° C. in an oil bath, and the crystallized product A and the filtrate a were separated by suction filtration.
[0052] (6) The crystalline product A was placed in a vacuum oven at 70°C for 12 hours to obtain a dry product.
[0053] (7) Weigh 35 g of the primary crystal product A, use a 500 ml round-bottom flask as a container, add 165 ml of deionized water to the raw material, raise the oil bath temperature to 55° C., and stir continuously until the lithium hydroxide raw material is completely dissolved to obtain solution B.
[0054] (8) Solution B was subjected to secondary evaporation crystallization. The round-bottom flask was kept heated in a water bath at 70° C. The flask rotation was set at 80 r / min. At the same time, the entire device was evacuated and the absolute pressure of the system was maintained at approximately 80 hPa.
[0055] (9) The lithium hydroxide solution was rotary evaporated for about 30 minutes. When the mass ratio of the crystallized product to the concentrated mother liquor in the solid solution mixture was 1:1.5, the rotary evaporation was stopped.
[0056] The subsequent treatment is the same as that of the primary crystallization product of lithium hydroxide, and the secondary crystallization product B and the filtrate b are obtained after cooling, filtration and drying.
[0057] (10) Weigh 20 g of the primary crystal product B, use a 250 ml round-bottom flask as a container, add 150 ml of deionized water to the raw material, raise the oil bath temperature to 55 °C, and stir continuously until the lithium hydroxide raw material is completely dissolved to obtain solution C.
[0058] (11) Solution C was subjected to secondary evaporation crystallization. The round-bottom flask was kept heated in a water bath at 70°C. The flask rotation was set at 80 r / min. At the same time, the entire device was evacuated and the absolute pressure of the system was maintained at approximately 40 hPa.
[0059] (12) The lithium hydroxide solution was rotary evaporated for about 20 min. When the mass ratio of the crystallized product to the concentrated mother liquor in the solid solution mixture was 1:1, the rotary evaporation was stopped.
[0060] (13) The subsequent treatment of the primary crystal product of lithium hydroxide is the same as that of the secondary crystal product of lithium hydroxide, and after cooling, filtration and drying, a tertiary crystal product C and a filtrate c are obtained.
[0061] (14) The filtrate b and the filtrate c are retained and added to the lithium hydroxide solution for the next multiple evaporation and crystallization operation to carry out a cyclic evaporation and crystallization operation.
[0062] Example 3
[0063] A method for preparing battery-grade lithium hydroxide monohydrate by multiple crystallization of lithium hydroxide mother liquor, specifically comprising the following steps:
[0064] (1) Using a 1000 ml round-bottom flask as a container, weigh 70 g of lithium hydroxide raw material, add 400 ml of deionized water to the raw material, heat the oil bath to 55° C., and stir continuously until the lithium hydroxide raw material is completely dissolved to obtain solution A.
[0065] (2) The homogeneous solution A is placed in a round-bottom flask, and the raw material is pretreated using a rotary evaporator to obtain a uniformly mixed lithium hydroxide raw material.
[0066] (3) Dissolving the lithium hydroxide raw material in step (2) again, evaporating and crystallizing the obtained lithium hydroxide raw material once, heating the round-bottom flask in a water bath at 80° C., rotating the flask at 80 rpm, and evacuating the entire device at the same time, maintaining the absolute pressure of the system at approximately 100 hPa.
[0067] (4) Rotary evaporation of the lithium hydroxide solution for about 40 minutes, when the mass ratio of the crystallized product to the concentrated mother liquor in the solid solution mixture is 1:1, the rotary evaporation is stopped.
[0068] (5) The solid solution mixture obtained in step (4) is cooled to 30° C. in an oil bath, and the crystalline product A and the filtrate a are separated by suction filtration.
[0069] (6) The crystalline product A was placed in a vacuum oven at 70°C for 12 hours to obtain a dry product.
[0070] (7) Weigh 35 g of the primary crystal product A, use a 500 ml round-bottom flask as a container, add 200 ml of deionized water to the raw material, raise the oil bath temperature to 55° C., and stir continuously until the lithium hydroxide raw material is completely dissolved to obtain solution B.
[0071] (8) Solution B was subjected to secondary evaporation crystallization. The round-bottom flask was kept heated in a water bath at 80° C. The flask rotation was set at 80 r / min. At the same time, the entire device was evacuated and the absolute pressure of the system was maintained at around 80 hPa.
[0072] (9) The lithium hydroxide solution was rotary evaporated for about 30 minutes. When the mass ratio of the crystallized product to the concentrated mother liquor in the solid solution mixture was 1:1, the rotary evaporation was stopped.
[0073] The subsequent treatment is the same as that of the primary crystallization product of lithium hydroxide, and the secondary crystallization product B and the filtrate b are obtained after cooling, filtration and drying.
[0074] (10) Weigh 20 g of the primary crystal product B, use a 250 ml round-bottom flask as a container, add 150 ml of deionized water to the raw material, raise the oil bath temperature to 55 °C, and stir continuously until the lithium hydroxide raw material is completely dissolved to obtain solution C.
[0075] (11) Solution C was subjected to secondary evaporation crystallization. The round-bottom flask was kept heated in a water bath at 80° C. The flask rotation was set at 80 r / min. At the same time, the entire device was evacuated and the absolute pressure of the system was maintained at approximately 40 hPa.
[0076] (12) The lithium hydroxide solution was rotary evaporated for about 20 min. When the mass ratio of the crystallized product to the concentrated mother liquor in the solid solution mixture was 1:1, the rotary evaporation was stopped.
[0077] (13) The subsequent treatment of the primary crystal product of lithium hydroxide is the same as that of the secondary crystal product of lithium hydroxide, and after cooling, filtration and drying, a tertiary crystal product C and a filtrate c are obtained.
[0078] (14) The filtrate b and the filtrate c are retained and added to the lithium hydroxide solution for the next multiple evaporation and crystallization operation to carry out a cyclic evaporation and crystallization operation.
[0079] The content of the battery-grade lithium hydroxide product obtained by purifying battery-grade lithium hydroxide monohydrate by the dissolution crystallization method of the present invention is measured below.
[0080] Comparative Example
[0081] The present invention illustrates a traditional lithium hydroxide evaporation crystallization purification method
[0082] (1) Using a 500 ml round-bottom flask as a container, weigh 35 g of industrial-grade lithium hydroxide raw material and dissolve it in 200 ml of deionized water. Heat the oil bath to 50° C. and stir continuously until it is completely dissolved.
[0083] (2) The solution was transferred to an evaporation container for rotary evaporation. The round-bottom flask was heated in a water bath at 70°C. The rotation of the flask was set at 80 r / min. At the same time, the entire device was evacuated and the absolute pressure of the system was maintained at around 100 hPa.
[0084] (3) After rotary evaporation for 40 min, the obtained solid solution mixture was cooled and stirred at room temperature until the crystallization was completely precipitated;
[0085] (4) The obtained solid solution mixture is filtered to obtain a crystalline product, which is then transferred to a vacuum oven and dried at 80° C. for 12 h to obtain a purified lithium hydroxide product.
[0086] Table 1 Battery grade lithium hydroxide monohydrate D-1 content standard and Example 1-3, comparative example content determination
[0087]
[0088] As can be seen from Table 1, the battery-grade lithium hydroxide product obtained by the process of purifying battery-grade lithium hydroxide monohydrate by the dissolution crystallization method of the present invention can meet the standard requirements of battery-grade lithium hydroxide monohydrate D-1 level. When the test temperature of Example 3 is too high and the solid solution ratio content is reduced, the content of the product content will be increased. At the same time, it can be seen from the comparative example that the impurity content of the product obtained by the traditional lithium hydroxide evaporation crystallization process is too high and cannot meet the standard requirements of battery-grade lithium hydroxide monohydrate D-1 level.
[0089] Obviously, the above examples of the present invention are only used as illustrations to explain the present invention, and are not intended to limit the methods of the present invention. All obvious extensions or changes made on the basis of the present invention are within the scope of protection of the present invention.
Claims
1. A method for preparing battery-grade lithium hydroxide monohydrate by multiple crystallization of lithium hydroxide mother liquor, characterized in that: The process steps include: Step 1: Add lithium hydroxide raw material and solvent in corresponding proportions into a container and mix them evenly to obtain a mixed solution; Step 2: Evaporate and concentrate the mixed solution in step 1 to obtain a solid solution mixture I of a certain proportion, and separate by suction filtration to obtain a crystalline product A and a filtrate a; Step 3: dissolving the crystalline product A obtained in step 2 with deionized water, evaporating and concentrating to obtain a solid solution mixture II of a certain proportion, and filtering and separating to obtain the crystalline product B and the filtrate b; Step 4: dissolving the crystalline product B obtained in step 3, evaporating and concentrating to obtain a certain proportion of solid solution mixture III, and filtering and separating to obtain crystalline product C and filtrate c; In a possible design, experiment 4 should also include the recovery and purification of part of the filtrate: Step 5: Reflux the filtrate b obtained in step 3 and the filtrate c obtained in step 4 into the evaporation device in step 2 for recycling, thereby increasing the yield of lithium hydroxide.
2. The method for preparing battery-grade lithium hydroxide monohydrate by multiple crystallization of lithium hydroxide mother solution according to claim 1, characterized in that: In step 1, the mass ratio of lithium hydroxide to deionized water is 1:(5-10), the stirring speed is 300-700 r / min, and the temperature is 50-60°C.
3. The method for preparing battery-grade lithium hydroxide monohydrate by multiple crystallization of lithium hydroxide mother solution according to claim 1, characterized in that: The mass ratio of the crystalline product A of the solid solution mixture I obtained in step 2 to the filtrate a is 1:(1.5-2).
4. The method for preparing battery-grade lithium hydroxide monohydrate by multiple crystallization of lithium hydroxide mother solution according to claim 1, characterized in that: The ratio of the crystalline product B of the solid solution mixture II obtained in step three to the filtrate b is 1:(1-1.5).
5. The method for preparing battery-grade lithium hydroxide monohydrate by multiple crystallization of lithium hydroxide mother solution according to claim 1, characterized in that: The mass ratio of the crystalline product C of the solid solution mixture III obtained in step 4 to the filtrate c is 1:(0.5-1).
6. The method for preparing battery-grade lithium hydroxide monohydrate by multiple crystallization of lithium hydroxide mother solution according to claim 1, characterized in that: The water bath temperature of the rotary evaporator used in this method is 70-80°C, the rotation speed is 40-80r / min, and the internal absolute pressure is maintained at about 40-100hPa.