Preparation method of high-grade lithium chloride
By using barium chloride and oxalic acid to remove impurities from the mixed lithium solution, the problems of low lithium ion concentration and impurity introduction in the traditional lithium chloride preparation were solved, realizing efficient and convenient preparation of high-grade lithium chloride.
Patent Information
- Application Number
- CN202511439236.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-10
- Publication Date
- 2025-11-18
AI Technical Summary
Traditional lithium chloride preparation processes suffer from low lithium-ion concentrations, low production efficiency, complex impurity removal processes that easily introduce impurities, and reduced product purity.
The mixture formed by the first lithium-containing solution, the second lithium-containing solution, and the third lithium-containing solution was purified by barium chloride and oxalic acid, followed by solid-liquid separation and drying to prepare high-grade lithium chloride with a lithium content of not less than 99 wt%.
It achieves continuous impurity removal, broadens the scope of lithium resource utilization, efficiently recovers lithium resources, has a simple process, is easy to operate, introduces virtually no new impurities, and obtains high-grade lithium chloride.
Smart Images
Figure CN120964848A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of lithium chloride production, in particular to a preparation method of high-grade lithium chloride. BACKGROUND
[0002] With the continuous growth of the new energy vehicle industry, the demand for energy storage is booming due to the large-scale application of renewable energy, and the consumer electronics market is continuously expanding with the upgrading of intelligence, and these fields have a sustained and rapid growth in demand for lithium batteries, and the demand for metal lithium has increased rapidly. Metal lithium is usually prepared from lithium chloride by molten salt electrolysis (usually using a LiCl-KCl eutectic mixture), so the demand for lithium chloride has also increased significantly.
[0003] The traditional lithium chloride preparation process converts lithium carbonate into LiCl lithium liquid by reaction with hydrochloric acid, then adds an appropriate amount of barium chloride and sodium carbonate solid to the LiCl solution to remove sulfate and calcium ion impurities, filters, adjusts the pH of the filtrate with sodium hydroxide, and then uses spray drying to obtain anhydrous lithium chloride. The low concentration of lithium ions in the reaction process leads to low production efficiency, and the impurity removal process is complex, which can easily introduce other impurities and affect the purity of the product.
[0004] In view of this, the present application is proposed. SUMMARY
[0005] The present application aims to provide a preparation method of high-grade lithium chloride to solve or improve the above technical problems.
[0006] The present application can be achieved as follows: In a first aspect, the present application provides a preparation method of high-grade lithium chloride, comprising the following steps: using a decontamination reagent to decontaminate a mixed solution formed by a first lithium-containing solution, a second lithium-containing solution and a third lithium-containing solution, then performing solid-liquid separation, drying the separated liquid, and obtaining high-grade lithium chloride with a lithium content of not less than 99wt%; The first lithium-containing solution is obtained by dissolving a solid lithium salt other than lithium carbonate, lithium chloride, lithium sulfate and lithium hydroxide in water, and then removing at least part of Ca, Al, Fe and Si; The second lithium-containing solution is obtained by dissolving lithium carbonate in hydrochloric acid; The third lithium-containing solution is obtained by dissolving lithium chloride in water; The decontamination reagent includes barium chloride and oxalic acid.
[0007] In an optional embodiment, the preparation of the first lithium-containing solution comprises: dissolving the solid lithium salt in water, then performing a first reaction under the condition of a pH value of 8-10, then performing solid-liquid separation to obtain an intermediate solution; performing a second reaction on the intermediate solution under the condition of a pH value of 2-4, then performing solid-liquid separation to obtain the first lithium-containing solution.
[0008] In an optional embodiment, hydrochloric acid is used to adjust the pH value in the preparation of the first lithium-containing solution.
[0009] In an optional embodiment, the lithium content of the solid lithium salt is 30wt%-50wt%; and / or, the lithium content of the lithium carbonate is no more than 98wt%; and / or, the lithium content of the lithium chloride is no more than 99wt% In an optional embodiment, the preparation of the mixed solution comprises: mixing the first lithium-containing solution with the second lithium-containing solution, then heating and keeping warm, and adding the third lithium-containing solution.
[0010] In an optional embodiment, the volume ratio of the first lithium-containing solution, the second lithium-containing solution and the third lithium-containing solution is (1-2):(5-7):(2-3).
[0011] In an optional embodiment, the volume ratio of the first lithium-containing solution, the second lithium-containing solution and the third lithium-containing solution is 1:6.5:2.5.
[0012] In an optional embodiment, the heating temperature is no less than 95℃, and the keeping warm time is 20min-30min.
[0013] In an optional embodiment, the impurity removal is performed at a temperature of 60℃-100℃ and a pH value of 9-11 for 40min-120min.
[0014] In an optional embodiment, the impurity removal is performed at a temperature of 60℃-100℃ and a pH value of 9-11 for 80min-120min.
[0015] In an optional embodiment, the impurity removal is performed by first adding barium chloride to the mixed solution and reacting for 40min-60min, and then adding oxalic acid and reacting for 40min-60min.
[0016] In an optional embodiment, the substance used to adjust the pH value in the impurity removal process comprises at least one of sodium hydroxide and lithium hydroxide.
[0017] The beneficial effects of the present application include: The application forms a first lithium-containing solution by using low-grade solid lithium salt, a second lithium-containing solution by using lithium carbonate, and a third lithium-containing solution by using lithium chloride, and then the three solutions are mixed together, and the mixed solution is then purified by using barium chloride and oxalic acid. The method can realize continuous purification and preparation of lithium chloride without intermittent operation process. In addition, the method has strong adaptability to raw materials, widens the utilization range of lithium resources, realizes efficient recovery and comprehensive utilization of lithium resources. In addition, the method is simple and convenient to operate, basically does not introduce new impurities in the preparation process, and has a high impurity removal rate, so that high-purity lithium chloride can be obtained. BRIEF DESCRIPTION OF DRAWINGS
[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.
[0019] Figure 1 The process flow chart of the preparation method of high-purity lithium chloride provided by the present application. DETAILED DESCRIPTION
[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely. The specific conditions not mentioned in the embodiments are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be purchased in the market.
[0021] The preparation method of high-purity lithium chloride provided by the present application will be described in detail below.
[0022] The present application provides a preparation method of high-purity lithium chloride, as shown in Figure 1 The preparation method of high-purity lithium chloride provided by the present application will be described in detail below. The first lithium-containing solution is obtained by dissolving solid lithium salt other than lithium carbonate, lithium chloride, lithium sulfate, lithium hydroxide in water, and then removing at least part of Ca, Al, Fe and Si; The second lithium-containing solution is obtained by dissolving lithium carbonate in hydrochloric acid; The third lithium-containing solution is obtained by dissolving lithium chloride in water; The impurity removal reagent includes barium chloride and oxalic acid.
[0023] In some alternative embodiments, the content of lithium in the solid lithium salt can be 30wt%, 35wt%, 40wt%, 45wt% or 50wt%, or other values within the range of 30wt%~50wt%. The solid lithium salt can be some industrial lithium-containing waste, so as to achieve the transformation of waste into treasure.
[0024] In some alternative embodiments, the preparation of the first lithium-containing solution comprises: after dissolving the solid lithium salt in water, performing a first reaction under the condition of pH value of 8~10, and then performing solid-liquid separation to obtain an intermediate solution; performing a second reaction under the condition of pH value of 2~4, and then performing solid-liquid separation to obtain the first lithium-containing solution.
[0025] Exemplarily, the solid-liquid ratio of the solid lithium salt to water can be 1kg:13L~1kg:20L.
[0026] The first reaction can be performed under the condition of pH value of 8, 8.5, 9, 9.5 or 10. The first reaction is mainly used for removing Ca, Si, Al and part of Fe (divalent) in the solid lithium salt.
[0027] The second reaction can be performed under the condition of pH value of 2, 2.5, 3, 3.5 or 4. The second reaction is mainly used for removing part of Fe (trivalent) in the solid lithium salt.
[0028] The pH value involved in the above-mentioned first reaction and second reaction can be adjusted by hydrochloric acid.
[0029] It should be noted that the “removing” in the text means that it can be removed and can be removed, and does not mean that complete removal is achieved.
[0030] In some alternative embodiments, the pH value of the second lithium-containing solution is 2~4.
[0031] The lithium content of lithium carbonate forming the second lithium-containing solution is not more than 98wt%, such as 90wt%~98wt%. The molar ratio of lithium carbonate to hydrochloric acid can exemplarily be 1moL:2mol.
[0032] In some alternative embodiments, the content of Li in the third lithium-containing solution is 12.8g / L~16g / L (calculated by Li).
[0033] The lithium content of lithium chloride forming the third lithium-containing solution is not more than 99wt%, such as 98wt%~99wt%.
[0034] In some alternative embodiments, the preparation of the mixed solution can comprise: mixing the first lithium-containing solution with the second lithium-containing solution, then heating and keeping warm, and then adding the third lithium-containing solution, so that the content of Li in the lithium solution is 12.8 g / L to 21 g / L (calculated as Li).
[0035] It should be noted that if the first lithium-containing solution, the second lithium-containing solution and the third lithium-containing solution are mixed directly and then heated and kept warm, it is easy to cause violent reaction and thus the tank is likely to be broken, which may cause safety accidents, and colloidal precipitates are generated, which are difficult to filter and have low impurity removal efficiency. If the first lithium-containing solution, the second lithium-containing solution and the third lithium-containing solution are mixed directly without heating, it is easy to cause uneven mixing and insufficient impurity removal reaction, which cannot achieve the purpose of efficient purification and impurity removal (Al, Si, etc.).
[0036] In some alternative embodiments, the volume ratio of the first lithium-containing solution, the second lithium-containing solution and the third lithium-containing solution is (1-2):(5-7):(2-3). In some typical embodiments, the volume ratio of the first lithium-containing solution, the second lithium-containing solution and the third lithium-containing solution is 1:6.5:2.5.
[0037] In some alternative embodiments, the heating temperature is not less than 95°C, for example, it can be 95°C to 100°C. The keeping warm time can be 20 min to 30 min, such as 20 min, 25 min or 30 min, etc.
[0038] By mixing the first lithium-containing solution with the second lithium-containing solution under acidic conditions and then heating and keeping warm, a part of carbonate ions can be removed.
[0039] In some alternative embodiments, the content of Ca 2+ <1g / L, SO4 2- <1g / L, Ba 2+ <0.1g / L.
[0040] In some alternative embodiments, the impurity removal can be performed at a temperature of 60°C to 100°C (such as 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C, etc.), and a pH value of 9 to 11 (such as 9, 9.5, 10, 10.5 or 11, etc.) for 40 min to 120 min (such as 40 min, 60 min, 80 min, 100 min or 120 min, etc.).
[0041] Preferably, the impurity removal is performed at a temperature of 60-100℃ and a pH of 9-11 for 80-120 minutes, for example, barium chloride can be added to the mixture first and reacted for 40-60 minutes, and then oxalic acid is added and reacted for 40-60 minutes. In this way, the impurity removal rate is higher than when barium chloride and oxalic acid are added at the same time or when oxalic acid is added first and then barium chloride is added.
[0042] If the temperature for impurity removal is too low, small crystals are generated, which are difficult to filter, and the precipitation reaction is slow. If the temperature for impurity removal is too high, the energy consumption increases and water evaporates, which causes the equipment to be easily scaled. If the pH for impurity removal is too low, it is not conducive to effectively removing impurities (Fe, SO4 2- If the pH for impurity removal is too high, side reactions are easily generated, and reagents are wasted and the solution is diluted.
[0043] The substance used to adjust the pH in the above impurity removal process includes at least one of sodium hydroxide and lithium hydroxide. The sodium hydroxide and lithium hydroxide can be configured into a solution with a concentration of 5-20% to adjust the pH.
[0044] The reaction equations involved in the above impurity removal process include: SO4 2- + Ba 2+ → BaSO4; C2O4 2- + Ca 2+ → CaC2O4; C2O4 2- + Ba 2+ → BaC2O4; Ca 2+ + SO4 2- → CaSO4.
[0045] After impurity removal, the Ca 2+ The removal rate of SO4 2- The removal rate of SO4 2- is ≥90% (preferably ≥90.2%).
[0046] In some optional embodiments, after impurity removal, a filtration method can be used for solid-liquid separation, and the obtained liquid can be concentrated, crystallized and dried to obtain high-purity lithium chloride with a lithium content of not less than 99wt% (preferably not less than 99.15wt%).
[0047] As described above, the preparation method of high-purity lithium chloride provided by the present application is simple and convenient to operate, does not introduce new impurities during the preparation process, can have a high impurity removal rate, and can obtain high-purity lithium chloride.
[0048] The features and performance of the present application are further described in detail below with reference to the embodiments.
[0049] Embodiment 1 The embodiment provides a preparation method of high-grade lithium chloride, and comprises the following steps: S1: preparing a mixed solution.
[0050] S1-1: preparing a first lithium-containing solution.
[0051] A solid lithium salt with a lithium content of 37wt% (specifically recovered from lithium oxide, lithium nitride, etc.) is added into a first reaction kettle, and pure water is added for dissolution according to a solid-liquid ratio of 1kg:20L, so that a lithium salt solution is obtained. A large amount of bubbles are generated in the dissolution process, and the ammonia smell is heavy. After dissolution, the lithium salt solution is black.
[0052] The lithium salt solution is filtered to obtain a yellow filtrate and a black filter residue.
[0053] The filtrate is added into a second reaction kettle, industrial hydrochloric acid is added to adjust the pH to 9 for the first reaction, and a yellow intermediate solution is obtained. A large amount of heat is generated in the reaction process, and the temperature is about 80℃.
[0054] The intermediate solution is aged, and after aging for 30min, there is obvious yellow precipitation in the lower layer. Then, the yellow filter residue and colorless transparent filtrate are obtained after filtration, and the filtrate is transferred to a third reaction kettle.
[0055] Hydrochloric acid is added into the third reaction kettle to adjust the pH to 3 for the second reaction, and then aged for 30min. After aging, the blue filter residue and anhydrous transparent filtrate (i.e., the first lithium-containing solution) are obtained after filtration.
[0056] S1-2: preparing a second lithium-containing solution.
[0057] Low-grade lithium carbonate with a lithium content of 93wt% is placed in a fourth reaction kettle, and hydrochloric acid is slowly added until completely dissolved according to a molar ratio of lithium carbonate to hydrochloric acid of 1mol:2mol, so that the second lithium-containing solution is obtained.
[0058] S1-3: preparing a third lithium-containing solution.
[0059] Lithium chloride with a lithium content of 98wt% is placed in a fifth reaction kettle, and pure water is added for dissolution according to a solid-liquid ratio of 1kg:2L, so that the third lithium-containing solution with a concentration of 14g / L (calculated by Li) is obtained.
[0060] S1-4: the first lithium-containing solution is mixed with the second lithium-containing solution, then heated and kept, and then the third lithium-containing solution is added. After mixing, the lithium content in the lithium solution is 14.6g / L (calculated by Li).
[0061] The first lithium-containing solution is transferred into the second lithium-containing solution and stirred and mixed, heated to generate a large amount of bubbles (at this time, the temperature is greater than or equal to 95°C), and kept for 25 minutes, and then the kept solution is transported to the sixth reaction kettle, and the third lithium-containing solution is transported to the sixth reaction kettle and stirred and mixed to obtain a mixed solution. In the mixed solution, the volume ratio of the first lithium-containing solution, the second lithium-containing solution and the third lithium-containing solution is 1:6.5:2.5.
[0062] S2: Impurities in the mixed solution are removed by using a removal reagent, and solid-liquid separation is performed.
[0063] The temperature of the mixed solution in the sixth reaction kettle is controlled to be 80°C, and a sodium hydroxide solution with a concentration of 10wt% is added to adjust the pH value to 10, then an oxalic acid with an equal molar ratio is added and stirred and reacted for 50 minutes, and then barium chloride with an excess of 15% compared to the equal molar ratio is added and stirred and reacted for 50 minutes. After the reaction is completed, filtration is performed to obtain white filter residue and colorless transparent filtrate (i.e. lithium liquid after impurity removal).
[0064] S3: The colorless transparent filtrate in S2 is concentrated and crystallized to obtain high-grade lithium chloride with a lithium content of 99.19wt%.
[0065] The content of part of the chemical components in the mixed solution in S2 and the lithium liquid after impurity removal in S3 is shown in Table 1.
[0066] Table 1 Chemical component content
[0067] Example 2 The difference between this example and Example 1 is that in the impurity removal process of S2, barium chloride is added first, and then oxalic acid is added.
[0068] The content of part of the chemical components in the mixed solution in S2 and the lithium liquid after impurity removal in S3 is shown in Table 2.
[0069] Table 2 Chemical component content
[0070] S3: The colorless transparent filtrate in S2 is concentrated and crystallized to obtain high-grade lithium chloride with a lithium content of 99.24wt%.
[0071] Example 3 The present example provides a preparation method of high-grade lithium chloride, comprising the following steps: S1: Preparing a mixed solution.
[0072] S1-1: Preparing a first lithium-containing solution.
[0073] A solid lithium salt with a lithium content of 30wt% (specifically recovered from lithium oxide, lithium nitride, etc.) is added to a first reaction kettle, and pure water is added to dissolve it at a solid-liquid ratio of 1 kg:18 L to obtain a lithium salt solution.
[0074] The lithium salt solution is filtered to obtain a yellow filtrate and a black filter residue.
[0075] The filtrate is added to a second reaction kettle, industrial hydrochloric acid is added to adjust the pH to 8 for the first reaction, and a yellow intermediate solution is obtained.
[0076] The intermediate solution is aged, and after 30 minutes of aging, there is a clear yellow precipitate at the bottom, which is then filtered to obtain a yellow filter residue and a colorless transparent filtrate, which is transferred to a third reaction kettle.
[0077] Hydrochloric acid is added to the third reaction kettle to adjust the pH to 2 for the second reaction, and then aged for 30 minutes. After aging, filtration is performed to obtain a blue filter residue and a colorless transparent filtrate (i.e., a first lithium-containing solution).
[0078] S1-2: Preparation of a second lithium-containing solution.
[0079] Low-grade lithium carbonate with a lithium content of 93wt% is placed in a fourth reaction kettle, and hydrochloric acid is slowly added at a molar ratio of lithium carbonate to hydrochloric acid of 1 mol:2 mol until complete dissolution to obtain a second lithium-containing solution.
[0080] S1-3: Preparation of a third lithium-containing solution.
[0081] Lithium chloride with a lithium content of 99wt% is placed in a fifth reaction kettle, and pure water is added at a solid-liquid ratio of 1 kg:2 L to dissolve it, obtaining a third lithium-containing solution with a concentration of 13 g / L (calculated as Li).
[0082] S1-4: The first lithium-containing solution is mixed with the second lithium-containing solution, then heated and kept warm, and the third lithium-containing solution is added. After mixing, the lithium content in the lithium solution is 17 g / L (calculated as Li).
[0083] The first lithium-containing solution is transferred into the second lithium-containing solution and stirred to mix. Heating is performed until a large amount of bubbles are generated (at this time, the temperature is ≥95°C), and the mixture is kept warm for 20 minutes. Then, the heated mixture is transferred to a sixth reaction kettle, and the third lithium-containing solution is also transferred to the sixth reaction kettle and stirred to mix, obtaining a mixed solution. In the mixed solution, the volume ratio of the first lithium-containing solution, the second lithium-containing solution, and the third lithium-containing solution is 1.5:5.5:3.
[0084] S2: Impurity removal reagent is used to remove impurities from the mixed solution, and solid-liquid separation is performed.
[0085] The temperature of the mixed solution in the sixth reaction kettle was controlled at 80°C, and a 10wt% sodium hydroxide solution was added to adjust the pH value to 9, then an equal molar ratio of oxalic acid was added and stirred for 40 minutes, and then an excess of 15% barium chloride was added and stirred for 40 minutes. After the reaction was completed, filtration was performed to obtain white filter residue and colorless transparent filtrate (i.e. lithium liquid after impurity removal).
[0086] S3: The colorless transparent filtrate in S2 was concentrated and crystallized to obtain high-grade lithium chloride with a lithium content of 99.17wt%.
[0087] The chemical component content of the mixed solution in S2 and the lithium liquid after impurity removal in S3 is shown in Table 3.
[0088] Table 3 Chemical component content
[0089] Example 4 The present embodiment provides a method for preparing high-grade lithium chloride, comprising the following steps: S1: Preparation of a mixed solution.
[0090] S1-1: Preparation of a first lithium-containing solution.
[0091] A solid lithium salt with a lithium content of 43wt% (specifically recovered from lithium oxide, lithium nitride, etc.) was added to a first reaction kettle, and pure water was added to dissolve it at a solid-liquid ratio of 1kg:15L to obtain a lithium salt solution.
[0092] The above lithium salt solution was filtered to obtain a yellow filtrate and black filter residue.
[0093] The above filtrate was added to a second reaction kettle, industrial hydrochloric acid was added to adjust the pH to 10 for the first reaction, and a yellow intermediate solution was obtained.
[0094] The intermediate solution was aged, and after aging for 30 minutes, there was a clear yellow precipitate at the bottom, then filtered to obtain a yellow filter residue and colorless transparent filtrate, and the filtrate was transferred to a third reaction kettle.
[0095] Hydrochloric acid was added to the third reaction kettle to adjust the pH to 4 for the second reaction, then aged for 30 minutes, and after aging, filtration was performed to obtain blue filter residue and anhydrous transparent filtrate (i.e. first lithium-containing solution).
[0096] S1-2: Preparation of a second lithium-containing solution.
[0097] Low-grade lithium carbonate with a lithium content of 92wt% was placed in a fourth reaction kettle, and hydrochloric acid was slowly added at a molar ratio of lithium carbonate to hydrochloric acid of 1mol:2mol until complete dissolution to obtain a second lithium-containing solution.
[0098] S1-3: Preparation of a third lithium-containing solution.
[0099] Lithium chloride with a lithium content of 98 wt% was placed in a fifth reaction kettle, and pure water was added at a solid-liquid ratio of 1 kg:2 L to dissolve it, obtaining a third lithium-containing solution with a concentration of 15.5 g / L (calculated as Li).
[0100] S1-4: Mixing the first lithium-containing solution with the second lithium-containing solution, followed by heating and holding, and then adding the third lithium-containing solution, and after mixing, the lithium liquid has a Li content of 13.8 g / L (calculated as Li).
[0101] The first lithium-containing solution was transferred into the second lithium-containing solution and stirred and mixed, heated until a large amount of bubbles were generated (at this time, the temperature was ≥95°C), and held for 30 min, and then the held liquid was transported to a sixth reaction kettle, and the third lithium-containing solution was transported to the sixth reaction kettle and stirred and mixed, obtaining a mixed solution. In the mixed solution, the volume ratio of the first lithium-containing solution, the second lithium-containing solution, and the third lithium-containing solution was 1:7:2.
[0102] S2: Impurity removal of the mixed solution using a removal reagent, and solid-liquid separation.
[0103] The temperature of the mixed solution in the sixth reaction kettle was controlled at 90°C, and a sodium hydroxide solution with a concentration of 15 wt% was added to adjust the pH value to 11, and then an excess of 15% of barium chloride in equimolar ratio was added and stirred for 30 min, and an equimolar amount of oxalic acid was added and stirred for 30 min. After the reaction was completed, filtration was performed, obtaining white filter residue and colorless transparent filtrate (i.e., lithium liquid after impurity removal).
[0104] S3: Concentration and crystallization of the colorless transparent filtrate in S2, obtaining high-grade lithium chloride with a lithium content of 99.22 wt%.
[0105] The content of part of the chemical components of the mixed solution in S2 and the lithium liquid after impurity removal in S3 is shown in Table 4.
[0106] Table 4 Chemical component content
[0107] Comparative Example 1 The difference between this comparative example and Example 2 is that in the impurity removal process of S2, the barium chloride and oxalic acid were added and reacted for 25 min, respectively.
[0108] The content of part of the chemical components of the mixed solution in S2 and the lithium liquid after impurity removal in S3 is shown in Table 5.
[0109] Table 5 Chemical component content
[0110] Comparative Example 2 The difference between the present comparative example and Example 2 is that the temperature of the mixed solution in the sixth reactor is controlled at 25°C during the impurity removal process of S2.
[0111] The chemical component contents of the mixed solution in S2 and the lithium solution after impurity removal in S3 are shown in Table 6.
[0112] Table 6 Chemical component contents
[0113] Comparative Example 3 The difference between the present comparative example and Example 2 is that the pH value is 8 during the impurity removal process of S2.
[0114] The chemical component contents of the mixed solution in S2 and the lithium solution after impurity removal in S3 are shown in Table 7.
[0115] Table 7 Chemical component contents
[0116] Comparative Example 4 The difference between the present comparative example and Example 2 is that the pH value is 5.5 during the impurity removal process of S2.
[0117] The chemical component contents of the mixed solution in S2 and the lithium solution after impurity removal in S3 are shown in Table 8.
[0118] Table 8 Chemical component contents
[0119] Test Example The Ca 2+ and SO4 2- removal rates and the lithium content of the high-purity lithium chloride obtained by the above Examples 1-4 and Comparative Examples 1-4 are compared, and the results are shown in Table 9.
[0120] Table 9 Comparison results
[0121] As can be seen from Table 7, the method provided by the present application has a high Ca 2+ removal rate and SO4 2- removal rate, and high-purity lithium chloride can be obtained. Among them, the effect of Example 2 is the best.
[0122] As can be seen by comparing Comparative Examples 1-4 and Example 2, if the impurity removal conditions are not properly set, the Ca 2+ removal rate and / or the SO4 2- removal rate will be reduced, and the Ca 2+ removal rate and SO42- The removal rate has the effect of reducing the grade of the obtained lithium chloride product.
[0123] In summary, the preparation method of high-grade lithium chloride provided by the present application has simple process and convenient operation, does not introduce new impurities in the preparation process, can have a high impurity removal rate, and obtains high-grade lithium chloride.
[0124] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A method for preparing high-grade lithium chloride, characterized in that, Includes the following steps: The mixture formed by the first lithium-containing solution, the second lithium-containing solution and the third lithium-containing solution was purified by a purification reagent, followed by solid-liquid separation. The separated liquid was dried to obtain the high-grade lithium chloride with a lithium content of not less than 99 wt%. The first lithium-containing solution is obtained by dissolving solid lithium salts other than lithium carbonate, lithium chloride, lithium sulfate, and lithium hydroxide in water and then removing at least a portion of Ca, Al, Fe, and Si. The second lithium-containing solution is obtained by dissolving lithium carbonate in hydrochloric acid; The third lithium-containing solution is obtained by dissolving lithium chloride in water; The impurity removal reagents include barium chloride and oxalic acid.
2. The preparation method according to claim 1, characterized in that, The preparation of the first lithium-containing solution includes: dissolving the solid lithium salt in water, carrying out a first reaction at a pH of 8-10, followed by solid-liquid separation to obtain an intermediate solution; carrying out a second reaction at a pH of 2-4 in the intermediate solution, followed by solid-liquid separation to obtain the first lithium-containing solution; Preferably, hydrochloric acid is used to adjust the pH value during the preparation of the first lithium-containing solution.
3. The preparation method according to claim 1, characterized in that, The lithium content of the solid lithium salt is 30wt%~50wt%; And / or, the lithium content of the lithium carbonate does not exceed 98 wt%; And / or, the lithium content of the lithium chloride does not exceed 99 wt%.
4. The preparation method according to any one of claims 1 to 3, characterized in that, The preparation of the mixture includes: mixing the first lithium-containing solution with the second lithium-containing solution, then heating and keeping it at a certain temperature, and then adding the third lithium-containing solution.
5. The preparation method according to claim 4, characterized in that, The volume ratio of the first lithium-containing solution, the second lithium-containing solution, and the third lithium-containing solution is (1~2):(5~7):(2~3).
6. The preparation method according to claim 5, characterized in that, The volume ratio of the first lithium-containing solution, the second lithium-containing solution, and the third lithium-containing solution is 1:6.5:2.
5.
7. The preparation method according to claim 4, characterized in that, The heating temperature should not be lower than 95℃, and the holding time should be 20min~30min.
8. The preparation method according to claim 1, characterized in that, Impurity removal is carried out at a temperature of 60℃~100℃ and a pH value of 9~11 for 40min~120min; Preferably, the impurity removal is carried out at a temperature of 60℃~100℃ and a pH value of 9~11 for 80min~120min.
9. The preparation method according to claim 8, characterized in that, The impurity removal process involves first adding barium chloride to the mixture and reacting for 40 to 60 minutes, then adding oxalic acid and reacting for another 40 to 60 minutes.
10. The preparation method according to claim 8 or 9, characterized in that, The substances used to adjust the pH value during the impurity removal process include at least one of sodium hydroxide and lithium hydroxide.