CN109592699B - Preparation method of battery-grade lithium hydroxide - Google Patents
Preparation method of battery-grade lithium hydroxide Download PDFInfo
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Abstract
The invention provides a preparation method of battery-grade lithium hydroxide, which comprises the following steps: s1, reacting the brine containing lithium chloride with alkali liquor to precipitate lithium, and obtaining a lithium hydroxide crude product and a lithium precipitation mother liquor; and S2, sequentially carrying out primary washing, evaporative crystallization, secondary washing and drying on the crude lithium hydroxide product to obtain the battery-grade lithium hydroxide. The method provided by the invention can be used for preparing the battery-grade lithium hydroxide with the purity meeting the requirement, and particularly has low chloride ion content. Meanwhile, the method has the advantages of high lithium recovery rate, short flow, simple process, low cost, safety, environmental protection, easy industrial production and the like.
Description
Technical Field
The invention relates to the field of inorganic materials, in particular to a preparation method of battery-grade lithium hydroxide.
Background
At present, the methods for preparing lithium hydroxide by using lithium chloride as a raw material mainly comprise the following steps:
(1) causticizing method of lithium carbonate
Adding sodium carbonate into the lithium chloride solution to precipitate lithium carbonate; mixing lime milk with lithium carbonate, regulating the concentration of causticized liquid, heating to boil and stirring strongly, wherein the causticization reaction is as follows
Ca(OH)2+Li2CO3＝CaCO3+2LiOH.H2O
The reaction yielded a lithium hydroxide solution with a concentration of about 3.5% and the removal of insoluble residues (mainly CaCO)3) And after separation, decompressing, concentrating, crystallizing and drying the mother liquor to obtain a lithium hydroxide product. The process is mature at present, and the method is basically adopted for preparing the lithium hydroxide at present. However, the technique adopts sodium carbonate to precipitate lithium and calcium hydroxide to causticizeThe process has the advantages of long flow, large energy consumption, high cost and low conversion rate; the residual quantity of lithium in the causticized slag is large, and the obtained lithium hydroxide has high calcium content and can not be applied to the lithium battery anode material.
(2) Electrolytic process for lithium chloride
Electrolyzing refined bittern (LiCl as main component) as anode solution and lithium hydroxide solution as cathode solution to obtain Li+And (3) obtaining a lithium hydroxide monohydrate solution in a cathode chamber through a cationic membrane, and obtaining a lithium hydroxide monohydrate product through evaporation concentration, cooling crystallization, washing and drying. The lithium hydroxide prepared by the method has high quality and can reach a battery level. However, the whole treatment process of the technology is complex, the flow is long, the number of byproducts is large, and the overall energy consumption of the system is high; meanwhile, the requirement on electrode materials is high due to the corrosivity of lithium chloride; and the matched membrane is immature, the later maintenance cost is high, and the byproduct chlorine or hydrogen chloride is difficult to digest in the salt lake region.
(3) Causticizing method of lithium chloride
Patent CN106006675A discloses a method for preparing lithium hydroxide monohydrate by using lithium chloride solution as raw material, which comprises mixing lithium chloride solution with a certain concentration and alkali liquor with a certain concentration at a certain temperature and under a certain pressure to react, concentrating the reaction solution to obtain lithium hydroxide monohydrate precipitate, filtering, washing and drying the precipitate to obtain lithium hydroxide monohydrate product. However, the lithium hydroxide monohydrate product prepared by the method has low purity, cannot be applied to a lithium battery anode material, and has the defects of large lithium residue in the lithium precipitation mother liquor after causticization, large lithium loss, low single-pass yield and high cost.
(4) Other methods
Patent CN107108245A discloses a method for producing lithium hydroxide, which comprises preparing lithium hydroxide by causticizing sodium hydroxide and lithium chloride, heating to melt lithium hydroxide at 500 deg.c to produce anhydrous lithium hydroxide, filtering, quenching with water, and drying to obtain lithium hydroxide monohydrate. However, the method consumes large energy consumption and is not easy for industrial production.
In summary, the lithium hydroxide prepared by the current method for preparing lithium hydroxide has the problems of low purity, high chlorine content or high preparation cost.
Disclosure of Invention
The invention mainly aims to provide a preparation method of battery-grade lithium hydroxide, which aims to solve the problems of low purity, high chlorine content or high preparation cost of the lithium hydroxide during the preparation of the battery-grade lithium hydroxide in the prior art. In addition, the method has the advantages of short process flow, simple operation process, low production cost, less three wastes, safety, environmental protection and easy industrial production. Particularly, after the process is further optimized, the lithium recovery rate is high and the lithium resource loss is low.
In order to achieve the above object, according to one aspect of the present invention, there is provided a method for preparing battery-grade lithium hydroxide, comprising the steps of: s1, reacting the brine containing lithium chloride with alkali liquor to precipitate lithium, and obtaining a lithium hydroxide crude product and a lithium precipitation mother liquor; and S2, sequentially carrying out primary washing, evaporative crystallization, secondary washing and drying on the crude lithium hydroxide product to obtain the battery-grade lithium hydroxide.
Further, the method also comprises the following steps: s3, introducing a compound capable of introducing carbonate ions into water as a precipitator, and introducing the precipitator into a lithium precipitation mother solution for precipitation reaction to obtain a lithium carbonate crude product and a filtration mother solution; s4, evaporating, concentrating and drying the filtered mother liquor in sequence to obtain chloride.
Further, in step S1, the mass concentration of lithium chloride in the lithium chloride-containing brine is 27 to 35%, and the mass concentration of hydroxide ions in the alkali solution is 10 to 15%.
Further, in step S1, the reaction temperature during the reaction of depositing lithium is 0 to 95 ℃, and the reaction time is 10 to 120 min.
Further, the alkali liquor is sodium hydroxide aqueous solution, potassium hydroxide aqueous solution or ammonia water; when the alkali liquor is sodium hydroxide aqueous solution, the precipitator is sodium carbonate and/or carbon dioxide, and the chloride is sodium chloride; when the alkali liquor is a potassium hydroxide aqueous solution, the precipitator is potassium carbonate and/or carbon dioxide, and the chloride is potassium chloride; when the alkali liquor is ammonia water, the precipitant is ammonium carbonate and/or carbon dioxide, and the chloride is ammonium chloride.
Further, in step S2, the detergents used in the first washing and the second washing are both lithium hydroxide saturated solutions.
Further, in step S2, the temperature of the evaporative crystallization is 50-95 ℃ and the pressure is 0-0.1 MPa.
Further, in step S2, the evaporative crystallization process includes: mixing the lithium hydroxide crude product subjected to the first washing with water and completely dissolving to obtain a dissolved solution; heating the dissolved solution to evaporate part of water and separate out crystals to obtain a residual liquid; and cooling the residual liquid to finish the evaporative crystallization process.
Further, in the evaporation crystallization process, filtering the cooled residual liquid, and returning the filtrate to the first washing process; returning the washing liquid generated in the second washing process to the first washing process; and (4) further evaporating and crystallizing the washing liquid generated in the first washing process, then filtering, returning the obtained filtrate to the step S1 to participate in the lithium precipitation process as part of alkali liquor, and combining the obtained filter residue and the crude lithium hydroxide product to perform the first washing process.
Further, after obtaining the crude lithium carbonate product, step S3 further includes: and washing and drying the crude lithium carbonate in sequence to obtain the battery-grade lithium carbonate.
Further, returning a washing liquid generated in the process of washing the crude lithium carbonate product to the lithium precipitation mother liquid to participate in a precipitation reaction; preferably, after the step of performing evaporation concentration on the filtered mother liquor, the step S4 further includes: carrying out secondary filtration on the filtered mother liquor subjected to evaporation concentration to obtain a chloride crude product; washing the crude chloride product, and then drying to obtain industrial-grade chloride; preferably, the filtrate produced in the secondary filtration step is returned to step S3 for the preparation of a precipitant; preferably, the washing liquid produced during washing of the crude chloride is returned to the evaporative concentration step.
The invention provides a preparation method of battery-grade lithium hydroxide, which comprises the following steps: s1, reacting the brine containing lithium chloride with alkali liquor to precipitate lithium, and obtaining a lithium hydroxide crude product and a lithium precipitation mother liquor; and S2, sequentially carrying out primary washing, evaporative crystallization, secondary washing and drying on the crude lithium hydroxide product to obtain the battery-grade lithium hydroxide. The method provided by the invention can be used for preparing the battery-grade lithium hydroxide with purity meeting the requirement, and particularly has low chlorine content. Meanwhile, the method has the advantages of high lithium recovery rate, short process flow, simple operation process, low production cost, safety, environmental protection and easy industrial production.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
figure 1 shows a flow diagram of a method for preparing battery grade lithium hydroxide according to an exemplary embodiment of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.
As described in the background section, the prior art for preparing battery-grade lithium hydroxide has problems of low purity of lithium hydroxide, or severe loss of lithium, or high preparation cost.
In order to solve the above problems, the present invention provides a method for preparing battery-grade lithium hydroxide, as shown in fig. 1, comprising the following steps: s1, reacting the brine containing lithium chloride with alkali liquor to precipitate lithium, and obtaining a lithium hydroxide crude product and a lithium precipitation mother liquor; and S2, sequentially carrying out primary washing, evaporative crystallization, secondary washing and drying on the crude lithium hydroxide product to obtain the battery-grade lithium hydroxide.
In the step S1, a mixed solution of lithium hydroxide and chloride (such as sodium chloride or potassium chloride) can be obtained by causticizing brine. In the step, because the solubility of lithium hydroxide is very close to that of chloride impurities and the solubility has very small difference with the temperature change, if lithium hydroxide monohydrate is directly separated out through evaporation crystallization, a large amount of chloride is separated out along with the lithium hydroxide, and a large amount of chloride impurities are coated in a lithium hydroxide lattice structure in the process, so that the lithium hydroxide and the chloride impurities are difficult to completely separate even a large amount of washing procedures are adopted in the later stage, the purity of the prepared lithium hydroxide is low, particularly the chlorine content is very high, and the difficulty of preparing battery-grade lithium hydroxide with higher purity by causticizing the lithium hydroxide-containing brine. In the preparation method provided by the invention, before the step of evaporative crystallization in the step S2, chloride impurities in the crude lithium hydroxide product are removed by first washing, and then the battery-grade lithium hydroxide is prepared by evaporative crystallization and second washing, has low chlorine content, and can be directly applied to the lithium battery anode material. In addition, the method has the advantages of high lithium recovery rate, short process flow, simple operation process, low production cost, safety, environmental protection and easy industrial production.
In a preferred embodiment, the above preparation method further comprises the steps of: s3, introducing a compound capable of introducing carbonate ions into water as a precipitator, and introducing the precipitator into a lithium precipitation mother solution for precipitation reaction to obtain a lithium carbonate crude product and a filtration mother solution; s4, evaporating, concentrating and drying the filtered mother liquor in sequence to obtain chloride.
After the reaction is carried out to precipitate lithium, a large amount of chloride (such as sodium chloride or potassium chloride) impurities and part of non-precipitated lithium ions are remained in the obtained lithium precipitation mother liquor. The present invention precipitates the part of lithium ions by using the precipitation reaction in step S3, thereby reducing lithium loss during the preparation process. Then, the filtered mother liquor is evaporated, concentrated and dried to obtain a chloride byproduct. Therefore, the method provided by the invention can be used for preparing the battery-grade lithium hydroxide with the purity meeting the requirement, and effectively recovering the lithium element in the filtered mother liquor through precipitation treatment of the filtered mother liquor, thereby reducing the lithium loss.
In order to wash off the chloride impurities in the crude lithium hydroxide more sufficiently, in a preferred embodiment, in step S2, the detergents used in the first washing and the second washing are both lithium hydroxide saturated aqueous solutions. More preferably, in step S2, the temperature of the evaporative crystallization is 50 to 95 ℃ and the pressure is 0 to 0.1 MPa. The lithium hydroxide obtained under the process condition has higher purity.
In step S1, the lithium chloride-containing brine used in the above step may be prepared by a preparation method commonly used in the art, such as further concentrating the lithium chloride concentrated solution after salt lake adsorption and membrane treatment to form the reaction raw material. In a preferred embodiment, in step S1, the lithium chloride-containing brine has a mass concentration of 27 to 35% of lithium chloride and the alkaline solution has a mass concentration of 10 to 15% of hydroxide ions. Under the above reaction conditions, the efficiency of lithium hydroxide formation is better. Further preferably, in the step S1, the reaction temperature during the reaction for depositing lithium is 0 to 95 ℃, and the reaction time is 10 to 120 min.
Preferably, the alkali liquor is sodium hydroxide aqueous solution, potassium hydroxide aqueous solution or ammonia water. When the alkali liquor is sodium hydroxide aqueous solution, the precipitator is sodium carbonate and/or carbon dioxide, and the chloride is sodium chloride; when the alkali liquor is a potassium hydroxide aqueous solution, the precipitator is potassium carbonate and/or carbon dioxide, and the chloride is potassium chloride; when the alkali liquor is ammonia water, the precipitant is ammonium carbonate and/or carbon dioxide, and the chloride is ammonium chloride. When an aqueous solution of sodium hydroxide is used, the corresponding chloride is sodium chloride, when an aqueous solution of potassium hydroxide is used, the corresponding chloride is potassium chloride, and when aqueous ammonia is used, the corresponding chloride is ammonium chloride.
In a preferred embodiment, in step S2, the evaporative crystallization process includes: mixing the lithium hydroxide crude product subjected to the first washing with water and completely dissolving to obtain a dissolved solution; heating the dissolved solution to evaporate part of water and separate out crystals to obtain a residual liquid; and cooling the residual liquid to finish the evaporative crystallization process. Most impurities are removed in the first washing process, so that the purity of lithium hydroxide crystallized and separated out in the evaporation crystallization process is high. In the process of heating the dissolving solution, lithium hydroxide is crystallized and precipitated, and then the residual solution is cooled, thus completing the step of evaporative crystallization.
In a preferred embodiment, during the evaporative crystallization, the cooled residue is filtered and the filtrate is returned to the first washing. This is beneficial to the recycling of resources and can further reduce the lithium loss. More preferably, the portion of the solution is further concentrated by evaporation before being returned to remove a portion of the water and filtered before returning the filtrate. Preferably, the washing liquid produced in the second washing is returned to the first washing together.
In the first washing process, inevitably part of lithium hydroxide is washed and dissolved in the washing liquid, preferably, the washing liquid generated in the first washing process is further evaporated and crystallized, then filtered, the obtained filtrate is returned to the step S1 to participate in the reaction lithium precipitation process as part of alkali liquor, and the obtained filter residue and the crude lithium hydroxide are combined for the first washing. This is advantageous in further reducing lithium loss.
And after the second washing, preferably drying the lithium hydroxide filter cake after the second washing at the temperature of 50-80 ℃, and removing free water in the filter cake to finally obtain a battery-grade lithium hydroxide monohydrate product.
In order to further purify lithium carbonate, in a preferred embodiment, as shown in fig. 1, after obtaining crude lithium carbonate, step S3 further includes: and washing and drying the crude lithium carbonate in sequence to obtain the battery-grade lithium carbonate. Chloride impurities are remained in the crude lithium carbonate product generated through the precipitation reaction, and battery-grade lithium carbonate with higher purity can be obtained through washing and drying. Preferably, the detergent used in the process of washing the crude lithium carbonate is water.
In order to promote the maximum utilization of resources, in a preferred embodiment, as shown in fig. 1, the washing liquid generated in the process of washing the crude lithium carbonate is returned to the lithium precipitation mother liquid to participate in the precipitation reaction.
In a preferred embodiment, after the step of performing evaporation concentration on the filtered mother liquor, the step S4 further comprises: carrying out secondary filtration on the filtered mother liquor subjected to evaporation concentration to obtain a chloride crude product; washing the crude chloride product, and then drying to obtain the industrial grade chloride. Thus further purifying the chloride to obtain industrial grade chloride. Preferably, the filtrate produced in the secondary filtration step is returned to step S3 for the preparation of a precipitant; preferably, the washing liquid produced during washing of the crude chloride is returned to the evaporative concentration step. Therefore, all the washing liquid and mother liquid generated in the preparation method can be mechanically applied or prepared into original reaction liquid for use, thereby reducing the discharge of waste water and improving the recovery rate of lithium.
The beneficial effects of the present invention are further illustrated by the following examples:
example 1
The flow is shown in figure 1:
take 1m3Refining brine with the lithium content of 20g/L, concentrating until the lithium content is 44.5g/L (the mass concentration of LiCl is reduced to 27%), adding 443kg of sodium hydroxide solution with the mass concentration of 25.8% (the mass concentration of hydroxyl ions is 10.9%), reacting at room temperature for 60min to form a solid-liquid mixture containing lithium hydroxide precipitates, filtering the slurry, and washing with saturated lithium hydroxide solution to remove a large amount of sodium chloride impurities carried in a filter cake to obtain a lithium hydroxide filter cake; under the heating condition, after 300kg of deionized water is used for completely dissolving the lithium hydroxide filter cake, 2/3 water is heated and steamed, cooling crystallization is carried out, the crystallization temperature is controlled at 60 ℃, the pressure is controlled at 0.01MPa, and the lithium hydroxide filter cake with the chlorine content of 150ppm is obtained by filtration; washing the filter cake again to remove a small amount of residual sodium chloride impurities; and (3) drying the lithium hydroxide filter cake for 5h in vacuum at 50 ℃, removing free water in the filter cake, and finally obtaining 30kg of battery-grade lithium hydroxide monohydrate product with the purity of 98.6% and the chlorine content of 7 ppm.
Recovering lithium in the mother liquor: and adding sodium carbonate into the lithium precipitation mother liquor for reaction, washing and drying a filtered filter cake to obtain 70kg of battery-grade lithium carbonate with the purity of 99.8%. Evaporating, concentrating, filtering, washing and drying the filtrate to obtain an industrial-grade sodium chloride product.
And (3) treating a washing solution: combining the washing liquid obtained after the secondary washing of the lithium hydroxide crude product and the filtrate obtained by filtering the cooled residual liquid in the evaporative crystallization process, and then returning the filtrate to the primary washing process together; performing next evaporation crystallization, cooling and filtering on the washing liquid obtained in the first washing process, returning the obtained filtrate to the process for preparing alkali liquor, using the obtained filtrate as part of the alkali liquor to participate in the process of reaction and lithium precipitation, and combining the obtained filter residue and the crude lithium hydroxide product to perform the first washing process; returning the lithium carbonate washing liquid to the lithium precipitation mother liquid to continuously prepare lithium carbonate; returning the sodium chloride washing liquid to the evaporation concentration step; and returning the sodium chloride filtrate to prepare a sodium carbonate solution.
Example 2
The flow is shown in figure 1:
take 1m3Refining brine with the lithium content of 20g/L, concentrating until the lithium content is 44.5g/L (the mass concentration of LiCl is reduced to 27%), adding 443kg of sodium hydroxide solution with the mass concentration of 25.8% (the mass concentration of hydroxide ions is 10.9%), reacting for 120min at 80 ℃ to form a solid-liquid mixture containing lithium hydroxide precipitates, filtering the slurry, and washing with saturated lithium hydroxide solution to remove a large amount of sodium chloride impurities carried in a filter cake to obtain a lithium hydroxide filter cake; under the heating condition, after 300kg of deionized water is used for completely dissolving the lithium hydroxide filter cake, 2/3 water is heated and steamed, cooling crystallization is carried out, the crystallization temperature is controlled at 80 ℃, the pressure is controlled at 0.02MPa, and the lithium hydroxide filter cake with the chlorine content of 180ppm is obtained by filtration; washing the filter cake again to remove a small amount of residual sodium chloride impurities; and (3) drying the lithium hydroxide filter cake for 5h in vacuum at 50 ℃, removing free water in the filter cake, and finally obtaining 30kg of battery-grade lithium hydroxide monohydrate product with the purity of 98.5% and the chlorine content of 10 ppm.
Recovering lithium in the mother liquor: and adding sodium carbonate into the lithium precipitation mother liquor for reaction, washing and drying a filtered filter cake to obtain 70kg of battery-grade lithium carbonate with the purity of 99.8%. Evaporating, concentrating, filtering, washing and drying the filtrate to obtain an industrial-grade sodium chloride product.
And (3) treating a washing solution: combining the washing liquid obtained after the secondary washing of the lithium hydroxide crude product and the filtrate obtained by filtering the cooled residual liquid in the evaporative crystallization process, and then returning the filtrate to the primary washing process together; performing next evaporation crystallization, cooling and filtering on the washing liquid obtained in the first washing process, returning the obtained filtrate to the process for preparing alkali liquor, using the obtained filtrate as part of the alkali liquor to participate in the process of reaction and lithium precipitation, and combining the obtained filter residue and the crude lithium hydroxide product to perform the first washing process; returning the lithium carbonate washing liquid to the lithium precipitation mother liquid to continuously prepare lithium carbonate; returning the sodium chloride washing liquid to the evaporation concentration step; and returning the sodium chloride filtrate to prepare a sodium carbonate solution.
Example 3
The flow is shown in figure 1:
take 1m3Refining brine with the lithium content of 20g/L, concentrating until the lithium content is 52g/L (the mass concentration of LiCl is about 32 percent), adding 370kg of sodium hydroxide solution with the mass concentration of about 30.8 percent (the mass concentration of hydroxyl ions is 13.1 percent), reacting for 60min at 80 ℃ to form a solid-liquid mixture containing lithium hydroxide precipitates, filtering the slurry, and washing by using a saturated lithium hydroxide solution to remove a large amount of sodium chloride impurities carried in a filter cake to obtain a lithium hydroxide filter cake; under the heating condition, after 300kg of deionized water is used for completely dissolving the lithium hydroxide filter cake, 2/3 water is heated and steamed, cooling crystallization is carried out, the crystallization temperature is controlled at 60 ℃, the pressure is controlled at 0.01MPa, and the lithium hydroxide filter cake with the chlorine content of 200ppm is obtained by filtration; washing the filter cake again to remove a small amount of residual sodium chloride impurities; and (3) drying the lithium hydroxide filter cake for 5h in vacuum at 50 ℃, removing free water in the filter cake, and finally obtaining 60kg of battery-grade lithium hydroxide monohydrate product with the purity of 98.4% and the chlorine content of 10 ppm.
Recovering lithium in the mother liquor: and adding sodium carbonate or introducing carbon dioxide into the lithium precipitation mother liquor for reaction, washing and drying a filtered filter cake to obtain 45kg of battery-grade lithium carbonate with the purity of 99.5 percent. Evaporating, concentrating, filtering, washing and drying the filtrate to obtain an industrial-grade sodium chloride product.
And (3) treating a washing solution: combining the washing liquid obtained after the secondary washing of the lithium hydroxide crude product and the filtrate obtained by filtering the cooled residual liquid in the evaporative crystallization process, and then returning the filtrate to the primary washing process together; performing next evaporation crystallization, cooling and filtering on the washing liquid obtained in the first washing process, returning the obtained filtrate to the process for preparing alkali liquor, using the obtained filtrate as part of the alkali liquor to participate in the process of reaction and lithium precipitation, and combining the obtained filter residue and the crude lithium hydroxide product to perform the first washing process; returning the lithium carbonate washing liquid to the lithium precipitation mother liquid to continuously prepare lithium carbonate; returning the sodium chloride washing liquid to the evaporation concentration step; and returning the sodium chloride filtrate to prepare a sodium carbonate solution.
Example 4
The flow is shown in figure 1:
take 1m3The lithium content is 20g/L, the refined brine is concentrated to 52g/L (mass concentration of LiCl is about 32 percent), 370kg of sodium hydroxide solution (mass concentration of hydroxyl ions is 13.1 percent) with mass concentration of about 30.8 percent is added into the refined brine, the mixture reacts for 60min at room temperature to form a solid-liquid mixture containing lithium hydroxide precipitates, the slurry is filtered, and saturated lithium hydroxide solution is used for washing to remove a large amount of sodium chloride impurities carried in a filter cake, so that a lithium hydroxide filter cake is obtained; under the heating condition, after 300kg of deionized water is used for completely dissolving the lithium hydroxide filter cake, 2/3 water is heated and steamed, cooling crystallization is carried out, the crystallization temperature is controlled at 60 ℃, the pressure is controlled at 0.01MPa, and the lithium hydroxide filter cake with the chlorine content of 160ppm is obtained by filtration; washing the filter cake again to remove a small amount of residual sodium chloride impurities; and (3) drying the lithium hydroxide filter cake for 5h in vacuum at 50 ℃, removing free water in the filter cake, and finally obtaining 70kg of battery-grade lithium hydroxide monohydrate product with the purity of 98.6% and the chlorine content of 7 ppm.
Recovering lithium in the mother liquor: and adding sodium carbonate or introducing carbon dioxide into the lithium precipitation mother liquor for reaction, washing and drying a filtered filter cake to obtain 38kg of battery-grade lithium carbonate with the purity of 99.6 percent. Evaporating, concentrating, filtering, washing and washing the filtrate to obtain an industrial-grade sodium chloride product.
And (3) treating a washing solution: combining the washing liquid obtained after the secondary washing of the lithium hydroxide crude product and the filtrate obtained by filtering the cooled residual liquid in the evaporative crystallization process, and then returning the filtrate to the primary washing process together; performing next evaporation crystallization, cooling and filtering on the washing liquid obtained in the first washing process, returning the obtained filtrate to the process for preparing alkali liquor, using the obtained filtrate as part of the alkali liquor to participate in the process of reaction and lithium precipitation, and combining the obtained filter residue and the crude lithium hydroxide product to perform the first washing process; returning the lithium carbonate washing liquid to the lithium precipitation mother liquid to continuously prepare lithium carbonate; returning the sodium chloride washing liquid to the evaporation concentration step; and returning the sodium chloride filtrate to prepare a sodium carbonate solution.
Example 5
Take 1m3Refining brine with the lithium content of 20g/L, concentrating the refined brine to a lithium chloride solution with the lithium content of 57.6g/L (the mass concentration of LiCl is about 35 percent), adding 340kg of a sodium hydroxide solution with the mass concentration of about 33.6 percent (the mass concentration of hydroxyl ions is 14.3 percent), reacting at room temperature for 60min to form a solid-liquid mixture containing lithium hydroxide precipitates, filtering the slurry, and washing by using a saturated lithium hydroxide solution to remove a large amount of sodium chloride impurities carried in a filter cake to obtain a lithium hydroxide filter cake; under the heating condition, after 300kg of deionized water is used for completely dissolving the lithium hydroxide filter cake, 2/3 water is heated and steamed, cooling crystallization is carried out, the crystallization temperature is controlled at 80 ℃, the pressure is controlled at 0.02MPa, and the lithium hydroxide filter cake with the chlorine content of 250ppm is obtained by filtration; washing the filter cake again to remove a small amount of residual sodium chloride impurities; and (3) drying the lithium hydroxide filter cake for 5h in vacuum at 50 ℃, removing free water in the filter cake, and finally obtaining 72kg of battery-grade lithium hydroxide monohydrate product with the purity of 98.3% and the chlorine content of 18 ppm.
Recovering lithium in the mother liquor: and adding sodium carbonate or introducing carbon dioxide into the lithium precipitation mother liquor for reaction, washing and drying a filtered filter cake to obtain 36kg of battery-grade lithium carbonate with the purity of 99.5 percent. Evaporating, concentrating, filtering, washing and drying the filtrate to obtain an industrial-grade sodium chloride product.
And (3) treating a washing solution: combining the washing liquid obtained after the secondary washing of the lithium hydroxide crude product and the filtrate obtained by filtering the cooled residual liquid in the evaporative crystallization process, and then returning the filtrate to the primary washing process together; performing next evaporation crystallization, cooling and filtering on the washing liquid obtained in the first washing process, returning the obtained filtrate to the process for preparing alkali liquor, using the obtained filtrate as part of the alkali liquor to participate in the process of reaction and lithium precipitation, and combining the obtained filter residue and the crude lithium hydroxide product to perform the first washing process; returning the lithium carbonate washing liquid to the lithium precipitation mother liquid to continuously prepare lithium carbonate; returning the sodium chloride washing liquid to the evaporation concentration step; and returning the sodium chloride filtrate to prepare a sodium carbonate solution.
Example 6
Take 1m3Refining brine with the lithium content of 20g/L, concentrating the refined brine to a lithium chloride solution with the lithium content of 57.6g/L (the mass concentration of LiCl is about 35 percent), adding 350kg of a sodium hydroxide solution with the mass concentration of about 37.5 percent (the mass concentration of hydroxyl ions is 15 percent), reacting for 10min at 95 ℃ to form a solid-liquid mixture containing lithium hydroxide precipitates, filtering the slurry, and washing by using a saturated lithium hydroxide solution to remove a large amount of sodium chloride impurities carried in a filter cake to obtain a lithium hydroxide filter cake; under the heating condition, after 300kg of deionized water is used for completely dissolving the lithium hydroxide filter cake, 2/3 water is heated and steamed, cooling crystallization is carried out, the crystallization temperature is controlled at 95 ℃, the pressure is controlled at 0.05MPa, and the lithium hydroxide filter cake with the chlorine content of 230ppm is obtained by filtration; washing the filter cake again to remove a small amount of residual sodium chloride impurities; and (3) drying the lithium hydroxide filter cake for 5h in vacuum at the temperature of 80 ℃, removing free water in the filter cake, and finally obtaining 58kg of a battery-grade lithium hydroxide monohydrate product with the purity of 98.3% and the chlorine content of 16 ppm.
Recovering lithium in the mother liquor: and adding sodium carbonate or introducing carbon dioxide into the lithium precipitation mother liquor for reaction, washing and drying a filtered filter cake to obtain 47kg of battery-grade lithium carbonate with the purity of 99.5 percent. Evaporating, concentrating, filtering, washing and drying the filtrate to obtain an industrial-grade sodium chloride product.
And (3) treating a washing solution: combining the washing liquid obtained after the secondary washing of the lithium hydroxide crude product and the filtrate obtained by filtering the cooled residual liquid in the evaporative crystallization process, and then returning the filtrate to the primary washing process together; performing next evaporation crystallization, cooling and filtering on the washing liquid obtained in the first washing process, returning the obtained filtrate to the process for preparing alkali liquor, using the obtained filtrate as part of the alkali liquor to participate in the process of reaction and lithium precipitation, and combining the obtained filter residue and the crude lithium hydroxide product to perform the first washing process; returning the lithium carbonate washing liquid to the lithium precipitation mother liquid to continuously prepare lithium carbonate; returning the sodium chloride washing liquid to the evaporation concentration step; and returning the sodium chloride filtrate to prepare a sodium carbonate solution.
Example 7
Take 1m3Refining brine with the lithium content of 20g/L, concentrating the refined brine to a lithium chloride solution with the lithium content of 57.6g/L (the mass concentration of LiCl is about 35 percent), adding 350kg of a sodium hydroxide solution with the mass concentration of about 37.5 percent (the mass concentration of hydroxide ions is 15 percent), reacting for 120min at 0 ℃ to form a solid-liquid mixture containing lithium hydroxide precipitates, filtering the slurry, and washing by using a saturated lithium hydroxide solution to remove a large amount of sodium chloride impurities carried in a filter cake to obtain a lithium hydroxide filter cake; under the heating condition, after 300kg of deionized water is used for completely dissolving the lithium hydroxide filter cake, 2/3 water is heated and steamed, cooling crystallization is carried out, the crystallization temperature is controlled at 50 ℃, the pressure is controlled at 0.009MPa, and the lithium hydroxide filter cake with the chlorine content of 260ppm is obtained by filtration; washing the filter cake again to remove a small amount of residual sodium chloride impurities; and (3) drying the lithium hydroxide filter cake for 5h in vacuum at the temperature of 80 ℃, removing free water in the filter cake, and finally obtaining 60kg of battery-grade lithium hydroxide monohydrate product with the purity of 98.3% and the chlorine content of 20 ppm.
Recovering lithium in the mother liquor: and adding sodium carbonate or introducing carbon dioxide into the lithium precipitation mother liquor for reaction, washing and drying a filtered filter cake to obtain 45kg of battery-grade lithium carbonate with the purity of 99.5 percent. Evaporating, concentrating, filtering, washing and drying the filtrate to obtain an industrial-grade sodium chloride product.
And (3) treating a washing solution: combining the washing liquid obtained after the secondary washing of the lithium hydroxide crude product and the filtrate obtained by filtering the cooled residual liquid in the evaporative crystallization process, and then returning the filtrate to the primary washing process together; performing next evaporation crystallization, cooling and filtering on the washing liquid obtained in the first washing process, returning the obtained filtrate to the process for preparing alkali liquor, using the obtained filtrate as part of the alkali liquor to participate in the process of reaction and lithium precipitation, and combining the obtained filter residue and the crude lithium hydroxide product to perform the first washing process; returning the lithium carbonate washing liquid to the lithium precipitation mother liquid to continuously prepare lithium carbonate; returning the sodium chloride washing liquid to the evaporation concentration step; and returning the sodium chloride filtrate to prepare a sodium carbonate solution.
It should be noted that, similar effects can be obtained by replacing the alkali solution in the above embodiments with the potassium hydroxide aqueous solution or the ammonia water, and details are not described herein.
In a word, by the preparation method provided by the invention, the battery-grade lithium hydroxide monohydrate is obtained through reaction, the one-way yield is 25-61%, and the total one-way recovery rate of lithium of the lithium hydroxide monohydrate and lithium carbonate is 91.2-94.3%. The single-pass yield is shown here, and means the single treatment yield after each washing solution and the like are not recycled, and in the actual operation process, because each washing solution is recycled, the lithium yield can be further improved, which is understood by those skilled in the art.
The content/% of each component of the battery-grade lithium hydroxide product in the embodiment 1 of the invention is as follows:
| chemical composition | LiOH.H2O | Na | Cl- | Fe | Ca | Mg | SO4 2- | CO3 2- |
| Mass fractionFraction/%) | ＞98 | 0.0027 | 0.0007 | 0.0001 | 0.0002 | 0.0036 | 0.005 | 0.7 |
| Chemical composition | Li2CO3 | Na | Cl- | Fe | Ca | Mg | SO42- |
| Mass fraction/% | ＞99.5 | 0.0025 | 0.0007 | 0.0001 | 0.001 | 0.007 | 0.02 |
Comparative example 1
The lithium hydroxide is prepared by adopting the refining-washing process in the patent CN106006675A, and compared with the process of the invention, the process lacks the first washing before evaporative crystallization, and the specific flow is as follows:
take 1m3Concentrating the refined brine (the lithium content is 20g/L) until the lithium content is 44.5g/L (the mass concentration of LiCl is reduced to about 27%), adding 243kg of sodium hydroxide solution (the mass concentration of hydroxide ions is 20%) with the mass concentration of about 47.1%, and reacting at room temperature for 30min to form a solid-liquid mixture containing lithium hydroxide precipitates. Heating to concentrate and crystallize the water in the solution to obtain slurry containing certain solid phase, filtering the slurry, and washing the lithium hydroxide filter cake with saturated lithium hydroxide solution three times and four times separately. And (3) drying the lithium hydroxide filter cake for 5h in vacuum at 50 ℃, removing free water in the filter cake, and finally obtaining 30kg of a lithium hydroxide monohydrate product with the purity of 97.8 percent, wherein the chlorine ion content in the lithium hydroxide product is 443ppm and 357ppm respectively, the chlorine content is very high, and the reacted lithium precipitation mother liquor is not treated any more.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A preparation method of battery-grade lithium hydroxide is characterized by comprising the following steps:
s1, reacting the brine containing lithium chloride with alkali liquor to precipitate lithium, forming a solid-liquid mixture containing lithium hydroxide precipitate, and filtering to obtain a lithium hydroxide crude product and a lithium precipitation mother liquor; the mass concentration of lithium chloride in the lithium chloride-containing brine is 27-35%, and the mass concentration of hydroxide ions in the alkali liquor is 10-15%;
s2, sequentially carrying out first washing, evaporative crystallization, second washing and drying on the crude lithium hydroxide product to obtain the battery-grade lithium hydroxide; the detergents adopted in the first washing and the second washing are lithium hydroxide saturated solutions;
in step S2, the evaporative crystallization process includes:
mixing the lithium hydroxide crude product subjected to the first washing with water and completely dissolving to obtain a dissolved solution;
heating the dissolved solution to evaporate part of water and separate out crystals to obtain a residual liquid;
cooling the residual liquid to finish the evaporative crystallization process;
in the evaporation and crystallization process, filtering the cooled residual liquid, and returning the filtrate to the first washing process; returning the washing liquid generated in the second washing process to the first washing process; and further evaporating and crystallizing the washing liquid generated in the first washing process, then filtering, returning the obtained filtrate to the step S1 as part of the alkali liquor to participate in the reaction lithium precipitation process, and combining the obtained filter residue and the crude lithium hydroxide product to perform the first washing process.
2. The method of claim 1, further comprising the steps of:
s3, introducing a compound capable of introducing carbonate ions into water as a precipitator, and introducing the precipitator into the lithium precipitation mother liquor to perform precipitation reaction to obtain a crude lithium carbonate product and a filtration mother liquor;
and S4, sequentially carrying out evaporation concentration, filtration and drying on the filtered mother liquor to obtain chloride.
3. The preparation method according to claim 1, wherein in the step S1, the reaction temperature in the reaction lithium deposition process is 0-95 ℃, and the reaction time is 10-120 min.
4. The production method according to claim 1 or 2, wherein the alkali solution is an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, or aqueous ammonia; when the alkali liquor is sodium hydroxide aqueous solution, the precipitator is sodium carbonate and/or carbon dioxide, and the chloride is sodium chloride; when the alkali liquor is a potassium hydroxide aqueous solution, the precipitator is potassium carbonate and/or carbon dioxide, and the chloride is potassium chloride; when the alkali liquor is ammonia water, the precipitant is ammonium carbonate and/or carbon dioxide, and the chloride is ammonium chloride.
5. The method according to claim 1, wherein in step S2, the temperature of the evaporative crystallization is 50 to 95 ℃, and the pressure is 0 to 0.1 MPa.
6. The preparation method according to claim 2, wherein after obtaining the crude lithium carbonate product, the step S3 further includes: and washing and drying the crude lithium carbonate in sequence to obtain the battery-grade lithium carbonate.
7. The preparation method according to claim 6, wherein a washing liquid generated in the process of washing the crude lithium carbonate is returned to the lithium precipitation mother liquor to participate in the precipitation reaction.
8. The production method according to claim 6, wherein the step S4 further includes, after the step of subjecting the filtration mother liquor to the evaporative concentration:
carrying out secondary filtration on the filtered mother liquor subjected to evaporation concentration to obtain a chloride crude product;
washing the crude chloride product, and then drying to obtain the industrial grade chloride.
9. The method according to claim 8, wherein a filtrate produced in the secondary filtration step is returned to the step S3 for configuring the precipitant.
10. The method according to claim 8, wherein a washing liquid generated during washing of the crude chloride is returned to the evaporation concentration step.
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| WO2022147632A1 (en) * | 2021-01-05 | 2022-07-14 | Sociedad Quimica Y Minera De Chile S.A. | Method for the production of lithium hydroxide (lioh) directly from lithium chloride (lici), without the need for an intermediate production of lithium carbonate or similar |
| US11339481B1 (en) | 2021-08-06 | 2022-05-24 | Lithium Ark Holding B.V. | Production of lithium hydroxide and lithium carbonate |
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