Industrial method for preventing scaling during continuous crystallization of lithium carbonate, lithium carbonate crystal and application of lithium carbonate crystal

Abstract

The invention provides a lithium carbonate continuous crystallization anti-scaling industrial method, a lithium carbonate crystal and application. The industrialization method comprises the following steps: S1, providing a lithium carbonate seed crystal solution, and adding the lithium carbonate seed crystal solution into a crystallizer; s2, simultaneously adding the lithium-containing solution and the sodium carbonate solution into the crystallizer, and stirring and mixing the lithium-containing solution and the sodium carbonate solution with the lithium carbonate seed crystal solution to obtain a reaction solution to be crystallized; s3, the solution to be crystallized is subjected to a constant-temperature reaction, and lithium carbonate crystals are obtained; wherein on the basis of the total mass of the lithium element in the lithium carbonate seed crystal solution and the lithium element in the lithium-containing solution, the mass ratio of the lithium element in the lithium carbonate seed crystal solution is 12.5%-30%. According to the lithium carbonate continuous crystallization anti-scaling industrial method provided by the invention, an initial site is provided for crystal nucleation through seed crystal strategy nucleation according to the heterogeneous nucleation characteristic of lithium carbonate, and lithium carbonate particles can be prevented from nucleation at the bottom or four walls of the crystallizer and further deposition and scale formation.

Description

Technical Field

[0001] The invention relates to the technical field of lithium carbonate production, and in particular to an industrial method for preventing scaling of lithium carbonate continuous crystallization, lithium carbonate crystals and applications. Background Art

[0002] Battery-grade lithium salt materials (such as lithium carbonate) are lithium salt raw materials for positive electrode materials and the main component of electrolytes for lithium-powered batteries. Their prices have continued to soar in recent years, and their market demand is extremely strong. Lithium resources are the basic raw materials for the preparation of lithium carbonate and are known as "white oil". Their strategic importance has basically become a global consensus, and countries around the world have listed lithium as a strategic resource. Li2CO3 is one of the most important raw materials in the lithium industry and has been widely used to manufacture positive electrode materials for lithium-ion batteries. This application requires high-quality Li2CO3 crystals with high purity, micron size, and narrow particle size distribution, so as to achieve good charge and discharge performance in the resulting electrode material. Due to the characteristics of inverse solubility, high-temperature reaction lithium precipitation is one of the most commonly used methods for producing Li2CO3 crystals. However, these crystallization methods often cause process scaling, aggravate crystal agglomeration and mother liquor inclusion, and fail to achieve the high yield and high purity required for actual industrial production, and do not meet the strict standards for battery-grade Li2CO3 crystals.

[0003] In the actual industrial production of lithium carbonate products, the more common problem of equipment scaling is: on the one hand, it is determined by the specific lithium carbonate system. Lithium carbonate crystals are easy to nucleate on heterogeneous surfaces, and their nucleation rate is significantly higher than homogeneous nucleation, which makes it easier for crystals to nucleate and grow on rough surfaces, thereby causing equipment scaling; on the other hand, it is caused by unreasonable production processes and equipment design. The reaction precipitation lithium crystallization process often has microscopic uneven mixing, resulting in local supersaturation, a large number of secondary crystal nuclei, crystal agglomeration and serious equipment scaling. At present, there is no mature process method to avoid scaling in the continuous reaction crystallization process of lithium carbonate.

[0004] In summary, finding an effective method to prevent lithium carbonate crystal particles from depositing on the wall of the crystallizer and solving the problems of scaling and low yield during the continuous reaction crystallization process is an urgent problem to be solved in the industrial production of lithium carbonate industry in my country. Summary of the invention

[0005] The main purpose of the present invention is to provide an industrial method for preventing scaling of continuous crystallization of lithium carbonate, lithium carbonate crystals and applications, so as to solve the problem of severe equipment scaling commonly faced in the actual industrial production of existing lithium carbonate products and the inability to achieve the yield and purity required by actual industrial production.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, there is provided an industrial method for preventing scaling of lithium carbonate continuous crystallization, the industrial method comprising: step S1, providing a lithium carbonate seed solution, adding the lithium carbonate seed solution into a crystallizer, wherein a stirring paddle is provided in the crystallizer; step S2, adding a lithium-containing solution and a sodium carbonate solution into the crystallizer at the same time and stirring and mixing with the lithium carbonate seed solution to obtain a reaction solution to be crystallized; step S3, subjecting the solution to be crystallized to a constant temperature reaction to obtain lithium carbonate crystals; wherein, based on the total mass of the lithium element in the lithium carbonate seed solution and the lithium element in the lithium-containing solution, the mass proportion of the lithium element in the lithium carbonate seed solution is 12.5%-30%.

[0007] Further, in step S1, the concentration of the lithium carbonate seed solution is 1×10 -2 g / mL-8×10 -2 g / mL.

[0008] Furthermore, the average particle size of the lithium carbonate seeds in the lithium carbonate seed solution is 5-20 μm.

[0009] Furthermore, the preparation method of lithium carbonate seed crystals includes: adding lithium carbonate seed crystal mother liquor into water at a temperature of 60-90° C., stirring at a constant temperature for 0-10 minutes, and obtaining a lithium carbonate seed crystal solution.

[0010] Furthermore, the water includes at least one of pure water, deionized water or distilled water, and preferably the water is grade tertiary pure water.

[0011] Furthermore, the rotation speed of the constant temperature stirring is 100-200 rpm.

[0012] Furthermore, a jacket is provided on the outside of the crystallizer, and the jacket is connected to a temperature control device.

[0013] Furthermore, in step S2, the molar ratio of carbonate in the sodium carbonate solution to lithium ions in the lithium-containing solution is 1-1.3:2.

[0014] Furthermore, the lithium content in the lithium-containing solution is 6-30 g / L.

[0015] Furthermore, the lithium-containing solution includes at least one of high-lithium brine, lithium chloride solution or lithium sulfate solution.

[0016] Further, the lithium-containing solution and the sodium carbonate solution are mixed with the lithium carbonate crystal solution under stirring at a stirring speed of 100-400 rpm.

[0017] Furthermore, in step S2, the lithium-containing solution is added at a rate of 2-6 mL / min.

[0018] Furthermore, the addition rate of the sodium carbonate solution is 1.5-4.5 mL / min.

[0019] Furthermore, in step S3, the temperature of the isothermal reaction is 60-90° C., and the time of the isothermal reaction is 30-120 min.

[0020] Furthermore, the isothermal reaction is carried out in a closed environment.

[0021] Furthermore, the isothermal reaction is carried out under stirring at a stirring speed of 300-400 rpm.

[0022] Further, in step S1, the distance between the end of the stirring paddle and the lowest end of the bottom of the crystallizer is 0.1%-2% of the length of the stirring paddle;

[0023] Furthermore, in step S2, when the lithium-containing solution and the lithium carbonate solution are added to the crystallizer until the page reaches 1 / 3-1 / 2 of the final liquid level height, the position of the end of the stirring paddle is adjusted so that the distance between the end of the stirring paddle and the lowest end of the bottom surface of the crystallizer is 1 / 3-2 / 3 of the final page height.

[0024] Furthermore, when adjusting the end position of the stirring paddle, the stirring speed is adjusted to 300-400 rpm.

[0025] Furthermore, step S3 includes: subjecting the solution to be crystallized to a constant temperature reaction to obtain a lithium carbonate crystal reaction solution, and filtering, washing, calcining and drying the lithium carbonate crystal reaction solution in sequence to obtain lithium carbonate crystals.

[0026] According to another aspect of the present invention, there is provided a lithium carbonate crystal, which is prepared according to the industrial method of the lithium carbonate crystal provided in the first aspect.

[0027] According to a third aspect of the present invention, there is provided a use of the lithium carbonate crystals in preparing positive electrode materials for lithium ion batteries.

[0028] By applying the technical solution of the present application, the industrial method for preventing the continuous crystallization of lithium carbonate provided by the present application provides an initial site for crystal nucleation through seeding strategy nucleation based on the heterogeneous nucleation characteristics of lithium carbonate, which can prevent lithium carbonate particles from nucleating at the bottom or four walls of the crystallizer and further depositing to form scale. At the same time, the industrial method for preventing the continuous crystallization of lithium carbonate provided by the present application solves the problem of scaling during the crystallization of lithium carbonate, ensures the feasibility of continuous production of lithium carbonate in actual industry, further reduces time cost, and improves production efficiency.

[0029] In addition, after the crystallization is completed, the lithium carbonate crystals obtained in the industrial method for continuous crystallization and anti-scaling of lithium carbonate provided by the present application are suspended in the solution, which is more conducive to reducing the loss of lithium elements and improving the yield and purity of lithium carbonate crystals, so that the single-pass reaction yield reaches more than 85%. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0031] Figure 1 This is a photo of the scaling on the wall of the crystallizer after the crystallization reaction is completed in Example 1;

[0032] Figure 2 This is a photo of the scaling on the wall of the crystallizer after the crystallization reaction is completed in Example 8;

[0033] Figure 3 This is a photo of the scaling on the wall of the crystallizer after the crystallization reaction is completed in Example 9;

[0034] Figure 4 This is a photo of the scaling on the wall of the crystallizer after the crystallization reaction in Comparative Example 1 is completed;

[0035] Figure 5 This is a photo of the scaling on the wall of the crystallizer after the crystallization reaction is completed in Comparative Example 2;

[0036] Figure 6 This is a photograph of the scaling on the crystallizer wall after the crystallization reaction was completed in Comparative Example 3. DETAILED DESCRIPTION

[0037] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0038] As analyzed in the background technology of this application, high temperature reaction lithium precipitation is one of the most commonly used methods for producing lithium carbonate crystals, but these crystallization methods often have serious equipment scaling, crystal agglomeration, and cannot achieve the yield and purity required by actual industrial production in actual industrial production. In order to solve this problem, this application provides an industrial method for continuous crystallization of lithium carbonate and anti-scaling, lithium carbonate crystals and applications.

[0039] In a first typical embodiment of the present application, an industrial method for preventing scaling of lithium carbonate continuous crystallization is provided, and the industrial method comprises: step S1, providing a lithium carbonate seed solution, and adding the lithium carbonate seed solution to a crystallizer, wherein a stirring paddle is provided in the crystallizer; step S2, adding a lithium-containing solution and a sodium carbonate solution to the crystallizer at the same time, stirring and mixing with the lithium carbonate seed solution to obtain a reaction solution to be crystallized; step S3, subjecting the solution to be crystallized to a constant temperature reaction to obtain lithium carbonate crystals, wherein the mass proportion of the lithium element in the lithium carbonate seed solution is 12.5%-30% based on the total mass of the lithium element in the lithium carbonate seed solution and the lithium element in the lithium-containing solution.

[0040] The industrial method for preventing the continuous crystallization of lithium carbonate from scaling provided in the present application provides an initial site for crystal nucleation based on the heterogeneous nucleation characteristics of lithium carbonate through seed strategy nucleation, which can inhibit the nucleation of lithium carbonate particles at the bottom or four walls of the crystallizer and further deposit and scale. At the same time, the industrial method for preventing the continuous crystallization of lithium carbonate provided in the present application solves the problem of scaling during the crystallization of lithium carbonate, ensures the feasibility of continuous production of lithium carbonate in actual industry, further reduces time cost, and improves production efficiency.

[0041] In addition, after the crystallization is completed, the lithium carbonate crystals obtained in the industrial method for continuous crystallization and anti-scaling of lithium carbonate provided by the present application are suspended in the solution, which is more conducive to reducing the loss of lithium elements and improving the yield and purity of lithium carbonate crystals, so that the single-pass reaction yield reaches more than 85%.

[0042] Specifically, in the method for preventing scaling of lithium carbonate continuous crystallization provided in the present application, the mass proportion of lithium element in the lithium carbonate seed solution can be 12.5%, 12.75%, 15%, 18%, 20%, 22%, 25%, 28%, 30% or a range value composed of any two values, based on the total mass of lithium element in the lithium carbonate seed solution and the lithium element in the lithium-containing solution. This is conducive to improving the preparation efficiency and yield of lithium carbonate crystals and reducing the probability of scaling.

[0043] In order to further improve the preparation efficiency of lithium carbonate crystals, in some embodiments, in step S1, the concentration of the lithium carbonate seed solution is 1×10 -2 g / mL-8×10 -2 g / mL. Specifically, the concentration of the lithium carbonate seed solution can be 1×10 -2 g / mL, 1.5×10 -2 g / mL, 2×10 -2 g / mL, 3×10 -2 g / mL, 4×10 -2 g / mL, 5×10 -2 g / mL, 6×10 -2 g / mL, 7×10 -2 g / mL, 8×10 -2 g / mL or a range of any two values.

[0044] In order to further improve the purity and yield of lithium carbonate crystals, the average particle size of lithium carbonate seeds in the lithium carbonate seed solution is preferably 5-20 μm. Specifically, the average particle size of lithium carbonate seeds can be 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, or a range consisting of any two values.

[0045] In order to further improve the purity of lithium carbonate crystals, preferably in the above step S1, the method for preparing the lithium carbonate seed solution includes: adding lithium carbonate seeds to water at a temperature of 60-90°C, stirring at a constant temperature for 0-10 minutes (excluding 0), to obtain a lithium carbonate seed solution.

[0046] The water temperature is controlled at 60-90°C, which is beneficial to uniform dispersion of lithium carbonate seed crystals on the one hand, and is also beneficial to controlling the crystallization rate of lithium carbonate to avoid crystal agglomeration or mother liquor inclusion on the other hand.

[0047] The solvent water in the above lithium carbonate seed solution includes but is not limited to a mixture of any one or more of pure water, deionized water or distilled water. In order to further avoid impurities in the water affecting the purity of the lithium carbonate crystals, the water is preferably grade tertiary pure water.

[0048] In order to further improve the dispersion efficiency of lithium carbonate seeds in water, the rotation speed of the constant temperature stirring is preferably 200-400 rpm. Specifically, the rotation speed of the constant temperature stirring can be 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm or a range consisting of any two values.

[0049] In order to facilitate the control of the crystallization temperature to remain constant, it is preferred that a jacket is provided on the outside of the crystallizer, and the jacket is connected to a temperature control device, so as to facilitate the temperature inside the crystallizer to be kept constant at 60-90°C through the temperature control device, thereby promoting the smooth progress of the crystallization process and reducing the occurrence of scaling.

[0050] In order to further improve the yield of lithium carbonate crystals, in the above step S2, the molar ratio of carbonate in the sodium carbonate solution to lithium ions in the lithium-containing solution is preferably 1-1.3: 2. Specifically, the molar ratio of carbonate to lithium ions is 1: 2, 1.05: 2, 1.1: 2, 1.15: 2, 1.2: 2, 1.25: 2, 1.3: 2 or a range consisting of any two values.

[0051] The amount of carbonate is adjusted so that the molar amount of carbonate ions in the reaction solution to be crystallized is ≥ 2 times the molar amount of lithium ions, so as to promote the full reaction of lithium ions to form lithium carbonate crystals, thereby improving the yield of lithium carbonate crystals.

[0052] In order to further improve the generation efficiency of lithium carbonate crystals, the content of lithium in the lithium-containing solution is preferably 6-30 g / L. Specifically, the content of lithium in the lithium-containing solution can be 6 g / L, 7 g / L, 8 g / L, 10 g / L, 12 g / L, 15 g / L, 18 g / L, 20 g / L, 25 g / L, 30 g / L or a range consisting of any two values.

[0053] The specific type of the above lithium-containing solution is not limited, and any commonly used lithium-containing solution in the art can be used, including but not limited to a mixed solution of any one or more of high-lithium brine, lithium chloride solution or lithium sulfate solution.

[0054] In order to further improve the yield of lithium carbonate crystals, preferably in the above-mentioned step S2, the addition rate of the lithium-containing solution is 2-6mL / min, and the addition rate of the sodium carbonate solution is 1.5-4.5mL / min. Specifically, the addition rate of the lithium-containing solution can be 2mL / min, 2.5mL / min, 3mL / min, 3.5mL / min, 4mL / min, 5mL / min, 6mL / min or the range value composed of any two numerical values. The addition rate of the sodium carbonate solution is such as 1.5mL / min, 1.8mL / min, 2mL / min, 2.5mL / min, 3mL / min, 3.5mL / min, 4mL / min, 4.5mL / min or the range value composed of any two numerical values.

[0055] In the above step S2, preferably stirring is continued during the dropwise addition process, and the stirring speed is 100-400 rpm to facilitate mixing the lithium-containing solution and the sodium carbonate solution evenly, and is more conducive to subsequent isothermal reaction to generate lithium carbonate crystals. Specifically, the stirring speed can be 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm or a range value consisting of any two values.

[0056] In order to avoid the formation of ring-shaped crystal scale as the liquid level rises during the addition of lithium-containing solution and sodium carbonate solution, in some embodiments, in step S1, the position of the end of the stirring paddle in the crystallizer is 0.05%-2% away from the lowest point of the bottom of the crystallizer (the setting method of the conventional stirring paddle varies according to the size of the stirring paddle). In the above step S2, the position of the end of the stirring paddle is adjusted as the liquid level rises when the lithium-containing solution and lithium carbonate solution are added to the crystallizer.

[0057] In some specific embodiments, when the lithium-containing solution and the lithium carbonate solution are added to the crystallizer until the liquid level reaches 1 / 3-1 / 2 of the final liquid level, the position of the end of the stirring paddle is adjusted so that its distance from the lowest end of the bottom surface of the crystallizer is 1 / 3-2 / 3 of the final liquid level.

[0058] In order to further reduce the occurrence of crystal scaling, it is preferred to adjust the speed of the stirring paddle to 300-400 rpm while adjusting the position of the stirring paddle, so as to facilitate more uniform mixing of the lithium-containing solution and the sodium carbonate solution, and further improve the yield of lithium carbonate crystals.

[0059] The industrial method for preventing scale in continuous crystallization of lithium carbonate provided in the present application adjusts the position of the end of the stirring paddle as the liquid level in the crystallizer rises during the mixing of the lithium-containing solution and the sodium carbonate solution with the lithium carbonate seed solution, so that the distance between the end of the stirring paddle and the lowest end of the bottom surface of the crystallizer is 1 / 3-2 / 3 of the final liquid level height, which can further reduce the risk of ring-shaped crystal scale formed by rising liquid level during the addition of lithium solution and sodium carbonate solution, and further improve the yield.

[0060] In the above step S3, in order to further promote the formation of lithium carbonate crystals, the temperature of the isothermal reaction is preferably 60-90°C, and the time of the isothermal reaction is 30-120min. Specifically, the temperature of the isothermal reaction can be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C or a range value consisting of any two values; the time of the isothermal reaction can be 30min, 40min, 50min, 80min, 100min, 120min or a range value consisting of any two values.

[0061] In order to avoid excessive crystal formation and affect the quality of lithium carbonate crystals, the isothermal reaction is preferably carried out under stirring, and the stirring rate is preferably 200-400 rpm. Specifically, the stirring rate during the isothermal reaction can be 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm or a range value composed of any two values.

[0062] In order to avoid the introduction of impurities during the isothermal reaction, it is preferred that the isothermal reaction be carried out in a closed environment.

[0063] In order to further improve the purity of lithium carbonate crystals, the above step S3 preferably includes: subjecting the solution to be crystallized to a constant temperature reaction to obtain a lithium carbonate crystal reaction solution, and filtering, washing, calcining and drying the lithium carbonate crystal reaction solution in sequence to obtain lithium carbonate crystals.

[0064] In some embodiments, the lithium carbonate crystals can be returned to step S1 as lithium carbonate seeds for preparing a lithium carbonate seed solution, thereby achieving continuous preparation of lithium carbonate crystals.

[0065] In a second typical embodiment of the present application, a lithium carbonate crystal is provided. The lithium carbonate crystal is prepared according to the industrial method for continuous crystallization and anti-scaling of lithium carbonate provided in the first typical embodiment.

[0066] The lithium carbonate crystals provided in the present application are prepared by an industrial method of lithium carbonate continuous crystallization and anti-scaling, which not only has a single-pass yield of more than 80%, but also has high purity and can be used to make positive electrode materials for lithium-ion batteries.

[0067] In a third typical embodiment of the present application, there is provided an application of the lithium carbonate crystals provided in the second typical embodiment in the preparation of positive electrode materials for lithium ion batteries.

[0068] As mentioned above, the lithium carbonate crystals prepared by the industrial method for continuous crystallization and anti-scaling of lithium carbonate provided in this application have high purity and can meet the raw material requirements of lithium-ion battery positive electrode materials. It has broad application prospects in the field of preparing lithium-ion battery positive electrode materials.

[0069] The beneficial effects of the present application will be further illustrated below in combination with embodiments and comparative examples.

[0070] Example 1

[0071] This embodiment provides an industrial method for preventing scaling of lithium carbonate continuous crystallization, which comprises the following steps:

[0072] (1) A crystallizer is provided, wherein the crystallizer contains tertiary pure water, and a jacket is provided on the outside of the crystallizer, and the jacket is connected to a temperature control device to control the temperature of the tertiary pure water in the crystallizer to be maintained at 90° C. Lithium carbonate seed crystals with an average particle size of 8 μm are added to the crystallizer, and stirred at a constant temperature at a speed of 200 rpm for 5 minutes to obtain a concentration of 8×10 -2 g / mL lithium carbonate seed solution.

[0073] (2) 24 g / L (in terms of lithium content) of high-lithium brine and 280 g / L of sodium carbonate solution were added dropwise to the crystallizer at a dropping rate of 3 mL / min and 2 mL / min, respectively, and the mixture was mixed with the lithium carbonate seed solution. The stirring rate was 200 rpm.

[0074] (3) When the reaction solution in the crystallizer is dripped to 1 / 2 of the final liquid level, the position of the end of the stirring paddle in the crystallizer is adjusted to 1 / 3 of the final liquid level, and the rotation speed is adjusted to 300 rpm, and high-lithium brine and sodium carbonate solution are continued to be dripped until the final liquid level to obtain a reaction solution to be crystallized. Among them, based on the total mass of lithium element in the lithium carbonate seed solution and the lithium element in the high-lithium brine, the mass proportion of lithium element in the lithium carbonate seed solution is 12.5%.

[0075] (4) The crystallization reaction is continued to be stirred at a constant temperature for 90 minutes to obtain a lithium carbonate crystal reaction solution, and the lithium carbonate crystal reaction solution is filtered, washed, calcined and dried in sequence to obtain lithium carbonate crystals; wherein the lithium carbonate crystals can be crushed and used as lithium carbonate seeds to continue to return to step (1) to prepare a lithium carbonate seed solution, thereby realizing continuous production.

[0076] Example 2

[0077] This embodiment provides an industrial method for preventing scaling of lithium carbonate continuous crystallization, which comprises the following steps:

[0078] (1) A crystallizer is provided, wherein the crystallizer contains tertiary pure water, and a jacket is provided on the outside of the crystallizer, and the jacket is connected to a temperature control device to control the temperature of the tertiary pure water in the crystallizer to be maintained at 75°C. Lithium carbonate seed crystals with an average particle size of 12 μm are added to the crystallizer, and stirred at a constant temperature at a speed of 200 rpm for 5 minutes to obtain a concentration of 7×10 -2 g / mL lithium carbonate seed solution.

[0079] (2) 16.8 g / L (in terms of lithium content) of high-lithium brine and 230 g / L of sodium carbonate solution were added dropwise to the crystallizer at a dropping rate of 3 mL / min and 2 mL / min, respectively, and the mixture was mixed with the lithium carbonate seed solution. The stirring rate was 200 rpm.

[0080] (3) When the reaction solution in the crystallizer is dripped to 2 / 3 of the final liquid level, the position of the end of the stirring paddle in the crystallizer is adjusted to 2 / 3 of the final liquid level, and the rotation speed is adjusted to 300 rpm, and the high-lithium brine and sodium carbonate solution are continued to be dripped until the final liquid level to obtain a reaction solution to be crystallized. Among them, based on the total mass of lithium element in the lithium carbonate seed solution and the lithium element in the high-lithium brine, the mass of lithium element in the lithium carbonate seed solution accounts for 20%.

[0081] (4) continuing the crystallization reaction under constant temperature stirring for 60 minutes to obtain a lithium carbonate crystal reaction solution, filtering, washing, calcining and drying the lithium carbonate crystal reaction solution in sequence to obtain lithium carbonate crystals; wherein the lithium carbonate crystal reaction solution can be used as a lithium carbonate crystal mother liquor and returned to step (1) to prepare a lithium carbonate seed solution, thereby realizing continuous production.

[0082] Example 3

[0083] This embodiment provides an industrial method for preventing scaling of lithium carbonate continuous crystallization, which comprises the following steps:

[0084] (1) A crystallizer is provided, wherein the crystallizer contains tertiary pure water, and a jacket is provided on the outside of the crystallizer, and the jacket is connected to a temperature control device to control the temperature of the tertiary pure water in the crystallizer to be maintained at 80° C. Lithium carbonate seed crystals with an average particle size of 15 μm are added to the crystallizer, and stirred at a constant temperature at a speed of 200 rpm for 5 minutes to obtain a concentration of 6×10 -2 g / mL lithium carbonate seed solution.

[0085] (2) 21 g / L (in terms of lithium content) of high-lithium brine and 240 g / L of sodium carbonate solution were added dropwise to the crystallizer at a dropping rate of 4.5 mL / min and 3 mL / min, respectively, and the mixture was mixed with the lithium carbonate seed solution. The stirring rate was 200 rpm.

[0086] (3) When the reaction solution in the crystallizer is dripped to 2 / 3 of the final liquid level, the position of the end of the stirring paddle in the crystallizer is adjusted to 2 / 3 of the final liquid level, and the rotation speed is adjusted to 300 rpm, and the high-lithium brine and sodium carbonate solution are continued to be dripped until the final liquid level to obtain a reaction solution to be crystallized. Among them, based on the total mass of lithium element in the lithium carbonate seed solution and the lithium element in the high-lithium brine, the mass of lithium element in the lithium carbonate seed solution accounts for 20%.

[0087] (4) continuing the crystallization reaction under constant temperature stirring for 30 minutes to obtain a lithium carbonate crystal reaction solution, filtering, washing, calcining and drying the lithium carbonate crystal reaction solution in sequence to obtain lithium carbonate crystals; wherein the lithium carbonate crystal reaction solution can be used as a lithium carbonate crystal mother liquor and returned to step (1) to prepare a lithium carbonate seed solution, thereby realizing continuous production.

[0088] Example 4

[0089] This embodiment provides an industrial method for preventing scaling of lithium carbonate continuous crystallization, which comprises the following steps:

[0090] (1) A crystallizer is provided, wherein the crystallizer contains tertiary pure water, and a jacket is provided on the outside of the crystallizer, and the jacket is connected to a temperature control device to control the temperature of the tertiary pure water in the crystallizer to be maintained at 75°C. Lithium carbonate seed crystals with an average particle size of 8 μm are added to the crystallizer, and stirred at a constant temperature at a speed of 100 rpm for 5 minutes to obtain a concentration of 6×10 -2 g / mL lithium carbonate seed solution.

[0091] (2) adding 15 g / L (in terms of lithium content) of high-lithium brine and 200 g / L of sodium carbonate solution to the lithium carbonate seed solution at a dropping rate of 4.5 mL / min and 3 mL / min, respectively, and mixing with the lithium carbonate seed solution, and stirring at a speed of 100 rpm;

[0092] (3) When the reaction solution in the crystallizer is added dropwise to 2 / 3 of the final liquid level, the position of the end of the stirring paddle in the crystallizer is adjusted to 1 / 2 of the final liquid level, and the rotation speed is adjusted to 300 rpm, and high-lithium brine and sodium carbonate solution are continued to be added dropwise until the final liquid level to obtain a reaction solution to be crystallized. Among them, based on the total mass of lithium element in the lithium carbonate seed solution and the lithium element in the high-lithium brine solution, the mass proportion of lithium element in the lithium carbonate seed solution is 25%.

[0093] (4) continuing the crystallization reaction under constant temperature stirring for 50 minutes to obtain a lithium carbonate crystal reaction solution, filtering, washing, calcining and drying the lithium carbonate crystal reaction solution in sequence to obtain lithium carbonate crystals; wherein the lithium carbonate crystal reaction solution can be used as a lithium carbonate crystal mother liquor and returned to step (1) to prepare a lithium carbonate seed solution, thereby realizing continuous production.

[0094] Example 5

[0095] The difference between this embodiment and embodiment 1 is that in step (1), the temperature control setting is adjusted so that the temperature inside the crystallizer is 60°C.

[0096] Example 6

[0097] The difference between this embodiment and embodiment 1 is that in step (1), the amount of lithium carbonate seed crystals is adjusted so that the concentration of the prepared lithium carbonate seed crystal solution is 1×10 -2 g / mL.

[0098] Example 7

[0099] The difference between this embodiment and embodiment 1 is that in step (1), the amount of lithium carbonate seed crystals is adjusted so that the concentration of the prepared lithium carbonate seed crystal solution is 14×10 -2 In step (2), the concentration of the sodium carbonate solution used is 380 g / L.

[0100] Example 8

[0101] The difference between this embodiment and embodiment 1 is that, during the preparation process of lithium carbonate crystals, the position of the end of the stirring paddle in the crystallizer is not adjusted from beginning to end.

[0102] Example 9

[0103] The difference between this embodiment and embodiment 1 is that the stirring speed of the stirring paddle is 100 rpm throughout the whole process.

[0104] Example 10

[0105] The difference between this embodiment and embodiment 1 is that the average particle size of the lithium carbonate seed crystals used in step (1) is 50 μm.

[0106] Embodiment 11

[0107] The difference between this embodiment and embodiment 1 is that the average particle size of the lithium carbonate seed crystals used in step (1) is 300 μm.

[0108] Comparative Example 1

[0109] The difference between this comparative example and Example 1 is that in step (1), no lithium carbonate seed crystals are added to the crystallizer.

[0110] Comparative Example 2

[0111] The difference between this comparative example and Example 1 is that, based on the total mass of lithium element in the lithium carbonate seed solution and lithium element in the high-lithium brine, the mass proportion of lithium element in the lithium carbonate seed solution is 5%.

[0112] Comparative Example 3

[0113] The difference between this comparative example and Example 1 is that, based on the total mass of lithium element in the lithium carbonate seed solution and lithium element in the high-lithium brine, the mass proportion of lithium element in the lithium carbonate seed solution is 35%.

[0114] Performance Testing

[0115] (1) The scaling of the crystallizer wall after the continuous crystallization of lithium carbonate crystals provided in the examples and comparative examples was observed, and the scaling rate was calculated. The results are shown in Table 1. The scaling rate was calculated as follows: scaling rate = (crystal scaling mass / carbonate crystal mass) × 100%.

[0116] (2) The yield and purity of lithium carbonate crystals prepared by the industrial methods provided in the examples and comparative examples were tested, and the results are shown in Table 1. The yield of lithium carbonate crystals (one reaction) = the mass of lithium element in lithium carbonate crystals / (the mass of lithium element in lithium carbonate seed crystals + the mass of lithium element in high-lithium brine) × 100%; the purity of lithium carbonate crystals was determined by high performance liquid chromatography.

[0117] Table 1

[0118]

[0119]

[0120] Note: The above yield refers to the yield of lithium carbonate crystals without scale.

[0121] Figure 1 This is a photo of the scaling of the crystallizer wall after the crystallization reaction in Example 1 is completed. Figure 1 It can be seen that there is no scaling on the wall of the crystallizer, which means that no scaling occurs during the entire reaction crystallization process, achieving zero scaling.

[0122] After the crystallization reaction in Example 2-6 was completed, no structure was found on the wall and surroundings of the crystallizer, which indicates that no scaling occurred during the entire reaction crystallization process, achieving zero scaling.

[0123] After the crystallization reaction was completed in Example 7, the crystallizer wall was observed to have a small amount of lithium carbonate particles deposited around the crystallizer wall and at the bottom. This indicates that the concentration of the lithium carbonate seed solution is too high, which will increase the risk of scaling.

[0124] Figure 2 This is a photo of the scaling of the crystallizer wall after the crystallization reaction is completed in Example 8. Figure 2 It can be seen that there is a small amount of ring-shaped crystal scale around the crystallizer wall. This indicates that if the stirring paddle is not adjusted during the addition of the lithium-containing solution and the sodium carbonate solution, there is a risk of generating ring-shaped crystal scale.

[0125] Figure 3 This is a photo of the scaling on the wall of the crystallizer after the crystallization reaction is completed in Example 9. Figure 3 It can be seen that during the dripping process of the lithium-containing solution and the sodium carbonate solution, when the liquid level reaches 1 / 3, there is a risk of generating ring crystal scale if the rotation speed is lower than 200 rpm.

[0126] After the crystallization reaction was completed in Example 10, the crystallizer wall was observed to find that a small amount of agglomerated lithium carbonate particles (not scaled) existed around the crystallizer wall. This indicates that the excessively large particle size of lithium carbonate seed crystals is accompanied by the risk of scaling.

[0127] After the crystallization reaction was completed in Example 11, a small amount of ring-shaped crystal scale was deposited around the crystallizer wall. This indicates that the lithium carbonate seed crystal size is too large and the scaling risk is increased, resulting in slight scaling.

[0128] Figure 4 This is a photo of the scaling of the crystallizer wall after the crystallization reaction in Comparative Example 1 was completed. Figure 4 It can be seen that a large amount of lithium carbonate particles are deposited around the walls and bottom of the crystallizer, and scaling is serious. This shows that without adding seed crystals, lithium carbonate crystals are heterogeneously nucleated and scaling is serious.

[0129] Figure 5 This is a photo of the scaling on the wall of the crystallizer after the crystallization reaction in Comparative Example 2 was completed. Figure 5 It can be seen that there are a lot of lithium carbonate particles deposited around the walls and bottom of the crystallizer, and the scaling is serious. This shows that too little seed is added, and the lithium carbonate crystals will still heterogeneously nucleate and scale seriously.

[0130] Figure 6 This is a photo of the scaling of the crystallizer wall after the crystallization reaction in Comparative Example 3 was completed. Figure 6 It can be seen that a small amount of lithium carbonate particles are deposited around the walls and bottom of the crystallizer. This shows that adding too much seed crystals will also increase the risk of scaling, increase costs, affect product quality, and is not suitable for industrial production.

[0131] From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the following technical effects: the industrial method for preventing the continuous crystallization of lithium carbonate from scaling provided by the present application provides an initial site for crystal nucleation through seed strategy nucleation based on the heterogeneous nucleation characteristics of lithium carbonate, which can prevent lithium carbonate particles from nucleating at the bottom or four walls of the crystallizer and further depositing to form scale. At the same time, the industrial method for preventing the continuous crystallization of lithium carbonate from scaling provided by the present application solves the problem of scaling during the crystallization of lithium carbonate, ensures the feasibility of continuous production of lithium carbonate in actual industry, breaks through the limitations of intermittent kettle reactions, further reduces time costs, and improves production efficiency.

[0132] In addition, after the crystallization is completed, the lithium carbonate crystals obtained in the industrial method for continuous crystallization and anti-scaling of lithium carbonate provided by the present application are suspended in the solution, which is more conducive to reducing the loss of lithium elements and improving the yield and purity of lithium carbonate crystals, so that the single-pass reaction yield reaches more than 85%.

[0133] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An industrial method for preventing scaling of lithium carbonate continuous crystallization, characterized in that: The industrial process comprises: Step S1, providing a lithium carbonate seed solution, and adding the lithium carbonate seed solution into a crystallizer, wherein the crystallizer is provided with a stirring paddle; Step S2, adding the lithium-containing solution and the sodium carbonate solution into the crystallizer at the same time and stirring and mixing with the lithium carbonate seed solution to obtain a reaction solution to be crystallized; Step S3, subjecting the solution to be crystallized to a constant temperature reaction to obtain lithium carbonate crystals; Wherein, based on the total mass of the lithium element in the lithium carbonate seed solution and the lithium element in the lithium-containing solution, the mass proportion of the lithium element in the lithium carbonate seed solution is 12.5%-30%.

2. The industrial method according to claim 1, characterized in that In step S1, the concentration of the lithium carbonate seed solution is 1×10 -2 g / mL-8×10 -2 g / mL; Preferably, the average particle size of the lithium carbonate seeds in the lithium carbonate seed solution is 5-20 μm.

3. The industrial method according to claim 1, characterized in that The step S1, the method for preparing the lithium carbonate seed solution comprises: adding lithium carbonate seed mother solution into water at a temperature of 60-90° C., and stirring at a constant temperature for 0-10 minutes to obtain the lithium carbonate seed solution; Preferably, the water includes at least one of pure water, deionized water or distilled water, and preferably the water is grade tertiary pure water; Preferably, the rotation speed of the constant temperature stirring is 100-200 rpm; Preferably, a jacket is provided on the outside of the crystallizer, and a temperature control device is connected to the jacket.

4. The industrial method according to claim 1, characterized in that In step S2, the molar ratio of carbonate in the sodium carbonate solution to lithium ions in the lithium-containing solution is 1-1.3:2; Preferably, the lithium content in the lithium-containing solution is 6-30 g / L; Preferably, the lithium-containing solution comprises at least one of high-lithium brine, lithium chloride solution or lithium sulfate solution; Preferably, the lithium-containing solution and the sodium carbonate solution are mixed with the lithium carbonate crystal solution under stirring at a stirring speed of 100-400 rpm.

5. The industrial method according to claim 1, characterized in that In step S2, the lithium-containing solution is added at a rate of 2-6 mL / min; Preferably, the sodium carbonate solution is added at a rate of 1.5-4.5 mL / min.

6. The industrial method according to claim 1, characterized in that: In step S3, the temperature of the isothermal reaction is 60-90° C., and the time of the isothermal reaction is 30-120 min; Preferably, the isothermal reaction is carried out in a closed environment; Preferably, the isothermal reaction is carried out under stirring at a stirring speed of 300-400 rpm.

7. The industrial process according to any one of claims 1 to 6, characterized in that In step S1, the distance between the end of the stirring paddle and the lowest end of the bottom of the crystallizer is 0.05%-2% of the length of the stirring paddle; In the step S2, when the lithium-containing solution and the lithium carbonate solution are added to the crystallizer until the liquid level reaches 1 / 3-1 / 2 of the final liquid level, the position of the end of the stirring paddle is adjusted so that the distance between the end of the stirring paddle and the lowest end of the bottom surface of the crystallizer is 1 / 3-2 / 3 of the final liquid level; Preferably, when adjusting the end position of the stirring paddle, the stirring speed is adjusted to 300-400 rpm.

8. The industrial process according to any one of claims 1 to 6, characterized in that The step S3 comprises: subjecting the solution to be crystallized to a constant temperature reaction to obtain the lithium carbonate crystal reaction solution, and filtering, washing, calcining and drying the lithium carbonate crystal reaction solution in sequence to obtain the lithium carbonate crystals.

9. The lithium carbonate crystal prepared by the industrial method according to any one of claims 1 to 8.

10. Use of the lithium carbonate crystal according to claim 9 in preparing positive electrode materials for lithium ion batteries.

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