CN117142499A - Method for preparing battery-grade lithium carbonate by strengthening carbonization short distance - Google Patents
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Abstract
The application provides a method for preparing battery-grade lithium carbonate by strengthening carbonization short distance, which comprises the following steps: preparing lithium hydroxide solution, adding a surfactant, and performing microporous filtration to obtain refined lithium hydroxide solution; and (3) introducing industrial carbon dioxide into the refined lithium hydroxide solution at a certain gas flow rate to carry out carbonization reaction, then carrying out solid-liquid separation and washing to obtain carbonized liquid and wet slag, and drying and crushing the wet slag to obtain the battery-grade lithium carbonate. The method can improve carbonization efficiency and carbon dioxide utilization rate, has the advantages of short flow, simple operation, low cost, environmental protection and the like, is favorable for coping with the situation that the demand of the market for battery-grade lithium carbonate is greater than that of battery-grade lithium hydroxide, and has considerable industrial application prospect.
Description
Technical Field
The application belongs to the technical field of preparation of lithium carbonate, and particularly relates to a method for preparing battery-grade lithium carbonate by strengthening carbonization short-range.
Background
Lithium ion batteries are the most important power batteries of new energy automobiles, and the lithium salt related industry is attracting attention. Lithium carbonate and lithium hydroxide are basic industrial products of lithium and have been widely used in the fields of lithium ion batteries, medicine, military aerospace and the like. Currently, the main lithium ion power battery positive electrode materials mainly comprise lithium iron phosphate and high-nickel ternary positive electrode materials, wherein the lithium iron phosphate takes battery-grade lithium carbonate as a lithium source, and the lithium source of the high-nickel ternary positive electrode materials is battery-grade lithium hydroxide. The lithium iron phosphate positive electrode material has a market share exceeding that of the high-nickel ternary positive electrode material by virtue of the safety and the manufacturing cost. Thus, the market demand for battery grade lithium hydroxide is gradually decreasing, while the demand for battery grade lithium carbonate is gradually increasing, and the selling price of battery grade lithium carbonate is reversely higher than that of battery grade lithium hydroxide since 5 months in 2023.
Under the drive of market price, the yield of battery grade lithium carbonate is increased greatly, however, the battery grade lithium carbonate has strict requirements on main content and impurities, and is usually prepared by using industrial grade lithium salt as a raw material. Current methods for industrially producing battery grade lithium carbonate include a hydropyrolysis method, a bipolar membrane carbonization method, and a causticizing carbonization method. Chinese patent document CN 115286017A discloses a method for preparing battery grade lithium carbonate, which uses the carbonization-hydrogenation reaction of carbon dioxide and crude lithium carbonate solution to obtain lithium bicarbonate solution, and pyrolyzes the lithium bicarbonate solution to obtain battery grade lithium carbonate, however, the pyrolysis process of the technology is not easy to control, the lithium loss is large, and the carbonization-hydrogenation efficiency is low. Chinese patent document CN 107298450B discloses a method for preparing lithium hydroxide and lithium carbonate by using a soluble lithium salt solution, in which a bipolar membrane electrodialyzer is used to perform bipolar membrane electrolysis on the soluble lithium salt solution to obtain a lithium hydroxide solution at a cathode, and then high-purity lithium carbonate is obtained by carbonization.
The carbonized liquid still contains lithium, and the current treatment technology of the carbonized liquid mainly comprises lithium precipitation of carbonate and phosphate, extraction, adsorption and the like. The extraction and adsorption method is a technology for selectively extracting lithium from carbonized liquid by utilizing a lithium extractant and a lithium ion sieve, and has high selectivity to lithium, however, the recycling difficulty of the extractant and the ion sieve is high, the investment cost is high, and the industrialized development is hindered. The lithium carbonate precipitation is still the treatment technology with the highest utilization rate at present, and Chinese patent document CN 104925837A discloses a method for preparing lithium salt by recovering battery-grade lithium carbonate precipitation mother liquor, wherein the method utilizes phosphoric acid precipitation lithium, has high lithium yield, but has environmental protection and cost pressure of phosphorus-containing wastewater treatment.
The preparation of battery grade lithium carbonate by carbonization of lithium hydroxide solution is a common method in industry, however, the carbonization process has long time and low efficiency, the utilization rate of carbon dioxide is still to be improved, and the current market has a demand for battery grade lithium carbonate larger than battery grade lithium hydroxide, but lacks a high-efficiency conversion method. Therefore, the development of a new technology for preparing battery-grade lithium carbonate by strengthening carbonization short-range has very important practical significance.
Disclosure of Invention
In order to solve the problems, the application provides a method for preparing battery grade lithium carbonate by strengthening carbonization short-range.
In order to achieve the above object, the present application proposes the following solution:
the method mainly comprises three steps of preparing a refined solution, carbonizing and treating liquid after carbonizing, and the inventor aims at the technical problems of long carbonizing time and low efficiency in the prior art that the lithium hydroxide solution is adopted to prepare lithium carbonate, in the process of carbonizing the lithium hydroxide solution by adopting carbon dioxide, a proper amount of additive is added into the lithium hydroxide solution, and then bubbles are promoted to be generated in the process of introducing the carbon dioxide into the solution at a proper gas introducing flow rate, so that the gas-liquid mass transfer process is enhanced, the time required by carbonizing can be shortened, and the utilization rate of the carbon dioxide can be improved.
Specifically, the application provides a method for preparing battery grade lithium carbonate by strengthening carbonization short distance, which comprises the following steps:
(1) Preparing lithium hydroxide solution, adding a surfactant, and performing microporous filtration to obtain refined lithium hydroxide solution;
(2) And (3) introducing industrial carbon dioxide into the refined lithium hydroxide solution at a gas flow rate of 0.03-0.3L/min per gram of lithium, performing carbonization reaction, performing solid-liquid separation and washing after carbonization to obtain carbonized liquid and wet slag, and drying and crushing the wet slag to obtain the battery-grade lithium carbonate.
In the technical scheme, the reaction formula for preparing lithium carbonate from the carbon dioxide lithium hydroxide solution is as follows:
CO 2 + OH - = HCO 3 - （1）
HCO 3 - + OH - = CO 3 2- + H 2 O（2）
2Li + + CO 3 2- = Li 2 CO 3 （3）
the carbon dioxide is firstly adsorbed into the solution to generate bicarbonate ions, namely a formula (1), when the hydroxyl ions exist in the solution, the bicarbonate ions are generated into carbonate ions, namely a formula (2), and precipitated lithium carbonate is formed, namely a formula (3), compared with the mass transfer between two phases of gas and liquid between the carbon dioxide and water, the three reactions of the formulas (1), (2) and (3) are all rapid, the mass transfer between the carbon dioxide and the water is a speed control step of carbonization reaction, the increase of the flow of the carbon dioxide is beneficial to improving the reaction speed, however, when the carbon dioxide is increased to a certain flow, the gas overflows into the solution without mass transfer, so that the utilization rate of the carbon dioxide is obviously reduced. According to the application, the alkali-resistant water-soluble surfactant is selected to be added into the lithium hydroxide solution, so that a large amount of bubbles are generated when the high-flow-rate carbon dioxide is blown into the lithium hydroxide solution, the gas-liquid mass transfer efficiency is remarkably improved, the overall reaction rate is further improved, the time for reaching the carbonization end point is shortened, and the purpose of strengthening carbonization is realized, namely, the addition of the surfactant can play an obvious role of bubbles under the condition of introducing a certain gas flow, so that the gas-liquid mass transfer is further strengthened, and the upper limit of the carbon dioxide introducing speed can be improved to accelerate the reaction, so that the addition of the surfactant improves the gas utilization rate on the premise of controlling a certain range of high gas flow rate. In addition, a large number of bubbles are generated in the carbonization process, so that the initial particle size of the product is reduced, and the cost of subsequent crushing is obviously reduced.
Preferably, in the step (2), the flow rate of the technical grade carbon dioxide is controlled to be 0.05-0.2L/min per gram of lithium.
Preferably, in the step (1), the surfactant is one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate and sodium laureth sulfate; the addition amount of the surfactant is determined according to the addition amount of 0.01-0.1 g of the surfactant per gram of lithium in the solution.
Preferably, the lithium content in the lithium hydroxide solution is 25 to 35g/L. When the concentration of lithium hydroxide is too low, the addition of the surfactant may reduce the gas utilization rate, and when the low-concentration lithium hydroxide solution is carbonized, the speed control step is a chemical reaction of hydroxyl to generate carbonate, and at the moment, the addition of the surfactant foams, which may aggravate the escape of carbon dioxide.
Preferably, in the step (2), the carbonization temperature is 20-80 ℃, the final pH value of carbonization is 9.5-10.5, and the Li content in the carbonized liquid is 2-6 g/L. The carbonization end point is controlled by the pH value.
In order to utilize lithium in the carbonized liquid, sodium carbonate is firstly utilized to precipitate lithium to prepare lithium carbonate, and as the solubility of lithium phosphate is far lower than that of lithium carbonate, the sodium phosphate is continuously utilized to precipitate lithium to prepare lithium phosphate, so that the lithium content in the carbonized liquid is further reduced. In addition, because the used medicament needs to be excessive, the phosphorus-containing wastewater is great in harm, calcium phosphate precipitation is prepared by using calcium salt to precipitate phosphorus in the phosphorus-containing wastewater, and the residual phosphorus-precipitating solution only contains soluble impurities such as sodium, potassium and the like and can be used as mother solution for recycling, and salt precipitation treatment is carried out after the concentration is increased. Preferably, the method further comprises a step (3), wherein the step (3) comprises: adding sodium carbonate into the carbonized liquid, carrying out solid-liquid separation after full reaction to obtain lithium carbonate, adding sodium phosphate into the liquid obtained by the solid-liquid separation, carrying out secondary centrifugal filtration after full reaction to obtain lithium phosphate, and adding calcium salt into the secondary centrifugal filtrate to obtain calcium slag and phosphorus-precipitating liquid.
Preferably, the addition amount of the sodium carbonate is 1.05 to 1.1 times of the theoretical lithium precipitation amount.
Preferably, the addition amount of the sodium phosphate is 1.05 to 1.1 times of the theoretical lithium precipitation amount; the calcium salt is calcium oxide and/or calcium hydroxide, the dosage of the calcium salt is 1.05-1.1 times of the theoretical phosphorus precipitation dosage, the calcium slag is used as a building filler, and the phosphorus precipitation post-liquid can be used as a mother liquid for recycling.
Preferably, in the step (2), in order to avoid the reaction of a large amount of carbon dioxide and lithium carbonate to generate lithium bicarbonate, the carbon dioxide escaping in the carbonization process is collected to a storage tank through a pipeline, compressed and purified and then recycled;
in the step (2), the solid-liquid separation is preferably centrifugal separation, and other conventional solid-liquid separation methods, such as filtration, may be used.
Preferably, the lithium hydroxide solution is prepared from lithium hydroxide and water; the lithium hydroxide is one or more of battery-grade lithium hydroxide monohydrate, battery-grade anhydrous lithium hydroxide, industrial-grade lithium hydroxide monohydrate and industrial-grade anhydrous lithium hydroxide, and the water is clear water or industrial pure water.
Preferably, in the step (3), the solid-liquid separation is centrifugal filtration.
Preferably, in step (1), the pore size of the microfiltration is not greater than 0.5 μm.
Compared with the prior art, the application has the following beneficial effects:
1. according to the application, the alkali-resistant water-soluble surfactant is added into the solution, and then a certain flow of carbon dioxide is introduced into the lithium hydroxide solution, so that a large number of bubbles are generated in the process of carbonizing the lithium hydroxide solution by adopting the carbon dioxide, the gas-liquid mass transfer of the carbon dioxide is obviously improved, the time for reaching the carbonization end point is obviously shortened, and the utilization rate and the production efficiency of the carbon dioxide are improved.
2. The surfactant used in the application has low cost and good water solubility, the prepared lithium carbonate product meets the requirement of battery level, and the initial particle size of the product is reduced by virtue of the generation of a large amount of bubbles in the carbonization process, so that the cost of subsequent crushing is obviously reduced.
3. The technical scheme provided by the application has the advantages of short flow, simplicity in operation, low cost, environment friendliness and the like, is favorable for coping with the situation that the demand of the market on battery-grade lithium carbonate is greater than that of battery-grade lithium hydroxide, and has considerable industrial application prospect.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a process flow diagram of example 1 of the present application.
FIG. 2 is a process flow diagram for the post-carbonization liquid treatment according to example 2 of the present application.
Detailed Description
The application will be described more fully hereinafter with reference to the accompanying drawings and preferred embodiments in order to facilitate an understanding of the application, but the scope of the application is not limited to the following specific embodiments.
Unless otherwise specifically indicated, the various raw materials, reagents, instruments, equipment and the like used in the present application are commercially available or may be prepared by existing methods.
Example 1:
technical LiOH H was prepared using the process scheme shown in FIG. 1 2 O (LiOH content: 56.6%) and industrial pure water were prepared into a lithium hydroxide solution 4L having a lithium content of 25g/L, wherein 2L of the solution was taken to be added with 0.5g of sodium dodecyl sulfate additive, and the other 2L of the solution was taken to be added with no additive, and was taken as group A, and as group B. A. After the two groups B are subjected to microporous filtration with the aperture of 0.5 mu m, carbon dioxide is respectively introduced into the two groups A under the constant temperature condition of 20 ℃, the air flow speed is 5L/min, and the bubbles generated in the groups A are obviously moreThe remaining group B. The solution of the group A needs to react for 16min to reach the pH value of 9.5, a large amount of white precipitate is generated, and carbonization is finished. The solution in group B needs to react for 27min to reach the pH value of 9.5, a large amount of white precipitate is generated, and carbonization is finished. The two groups of suspension liquid are respectively centrifugally filtered, washed and dried to obtain two groups of lithium carbonate, and the A group of lithium carbonate has the test granularity D 50 Test particle size D for 32 μm, group B lithium carbonate 50 67 μm. The result shows that after the sodium dodecyl sulfate additive is added, the time for reaching the carbonization end point is obviously shortened, and the analysis proves that the existence of the surfactant can improve the upper limit of the gas speed of the traditional carbonization reaction kettle (namely, the available carbon dioxide gas flow), or the upper limit of the gas speed forming speed control step of the traditional carbonization kettle, and after the surfactant is added, the effective upper limit of the gas flow speed is increased, so that the carbonization efficiency is improved. In addition, the initial granularity of the dried lithium carbonate is obviously reduced, and the pressure of the subsequent crushing process is obviously reduced. The concentration of lithium ions in the carbonized liquid is 1.76g/L.
After the A group lithium carbonate airflow is crushed, the granularity D50 of the obtained lithium carbonate product is 4 mu m, the purity is 99.80%, the other indexes are shown in table 1, and the results show that all indexes of the A group lithium carbonate reach the national standard of battery grade lithium carbonate.
Table 1 chemical composition of battery grade lithium carbonate (except for the noted units, the remaining units wt%) of the product obtained in group A of example 1
Example 2:
the carbonized solution of the group A in the embodiment 1 is treated by using the process flow shown in fig. 2, sodium carbonate with the theoretical lithium precipitation amount of 1.05 times is added into the carbonized solution, the reaction is filtered to obtain lithium carbonate solid and filtered solution, sodium phosphate with the lithium precipitation amount of 1.05 times is added into the obtained filtered solution to obtain lithium carbonate and lithium phosphate, the test purity is 98.6% and 98.2%, the standard of industrial grade lithium carbonate and lithium phosphate is reached, and the lithium hydroxide can be sold or used for causticizing to prepare lithium hydroxide. Calcium hydroxide with the theoretical phosphorus precipitation amount of 1.05 times is added into the solution after lithium precipitation to obtain calcium slag with components of calcium phosphate and calcium carbonate, the calcium slag can be used as building filler, and the solution after phosphorus precipitation does not contain phosphorus and can be used as mother solution for recycling.
Example 3:
technical LiOH H was prepared using the process scheme shown in FIG. 1 2 The solution of lithium hydroxide with the lithium content of 35g/L is prepared from 4L of O (LiOH content of 56.6%) and industrial pure water, 7g of sodium dodecyl benzene sulfonate additive is added into 2L of the solution to obtain a group C, and the other 2L of the solution is not added with the additive to obtain a group D. C. And D, after the two groups are subjected to microporous filtration with the aperture of 0.5 mu m, introducing carbon dioxide into the two groups at the constant temperature of 80 ℃ respectively, wherein the air flow speed is 5L/min, and the bubbles generated in the group C are obviously redundant in the group D. The solution of group C needs to react for 21min to reach the pH value of 10.5, a large amount of white precipitate is generated, and carbonization is finished. The solution D needs to react for 32min to reach the pH value of 10.5, a large amount of white precipitate is generated, and carbonization is finished. The two groups of suspension liquid are respectively centrifugally filtered, washed and dried to obtain two groups of lithium carbonate, and the C group of lithium carbonate has the test granularity D 50 Test particle size D of 34 μm, group D lithium carbonate 50 66 μm. The result shows that after the sodium dodecyl benzene sulfonate additive is added, the time for reaching the carbonization end point is obviously shortened, the initial granularity of the dried lithium carbonate is obviously reduced, and the pressure of the subsequent crushing process is obviously reduced. The concentration of lithium ions in the carbonized liquid is 2.04g/L.
After the C group lithium carbonate airflow is crushed, the granularity D50 of the obtained lithium carbonate product is 4 mu m, the purity is 99.62 percent, and the other indexes all reach the national standard of battery-grade lithium carbonate.
Example 4:
technical LiOH H was prepared using the process scheme shown in FIG. 1 2 The solution of lithium hydroxide with the lithium content of 30g/L is prepared from 4L of O (LiOH content of 56.6%) and industrial pure water, wherein 1g of sodium laureth sulfate additive is added into 2L of the solution to obtain the group E, and the other 2L of the solution is not added with the additive to obtain the group F. E. And after the two groups F are subjected to microporous filtration with the pore diameter of 0.5 mu m, introducing carbon dioxide into the two groups F respectively at the constant temperature of 50 ℃, wherein the air flow speed is 5L/min, and the bubbles generated by the groups E are obviously redundant. The solution E needs to react for 20min when the pH value reaches 10, a large amount of white precipitate is generated, and carbonization is finished. The solution of the group F needs to react for 28min when reaching the pH value of 10, a large amount of white precipitate is generated, and carbonization is finished. The two groups of suspension liquid are respectively centrifugally filtered, washed and dried to obtain two groups of lithium carbonate, and the E group of lithium carbonate is used for testing the granularity D 50 Test particle size D for 35 μm, group F lithium carbonate 50 62 μm. The result shows that after the sodium laureth sulfate additive is added, the time for reaching the carbonization end point is obviously shortened, the initial granularity of the dried lithium carbonate is obviously reduced, and the pressure of the subsequent crushing process is obviously reduced. The concentration of lithium ions in the carbonized liquid is 1.84g/L.
After the E group of lithium carbonate airflow is crushed, the granularity D50 of the obtained lithium carbonate product is 5 mu m, the purity is 99.77%, and the other indexes all reach the national standard of battery grade lithium carbonate.
Example 5:
technical LiOH H was prepared using the process scheme shown in FIG. 1 2 2L of lithium hydroxide solution with the lithium content of 30G/L is prepared from O (LiOH content of 56.6%) and industrial pure water, wherein 1L of the solution is taken to be added with 0.5G of sodium dodecyl sulfate additive to form a G group, and the other 1L of the solution is not added with the additive to form an H group. G. And after the two groups of H are subjected to microporous filtration with the aperture of 0.5 mu m, introducing carbon dioxide into the two groups of H respectively at the constant temperature of 50 ℃, wherein the air flow speed is 6L/min, and the bubbles generated by the group G are obviously redundant to the group H. The solution of group G needs to react for 11min when the pH value reaches 10, a large amount of white precipitate is generated, and carbonization is finished. The solution of the H group needs to react for 15min when the pH value reaches 10, a large amount of white precipitate is generated, and carbonization is finished. And (3) respectively centrifugally filtering, washing and drying the two groups of suspension liquid to obtain two groups of lithium carbonate, wherein the test granularity D50 of the group G lithium carbonate is 29 mu m, and the test granularity D50 of the group H lithium carbonate is 52 mu m. The result shows that after the sodium dodecyl sulfate additive is added, the time for reaching the carbonization end point is obviously shortened, the initial granularity of the dried lithium carbonate is reduced, and the pressure of the subsequent crushing process is reduced. The concentration of lithium ions in the carbonized liquid is 1.87g/L.
After the G group of lithium carbonate air flows are crushed, the granularity D50 of the obtained lithium carbonate product is 4 mu m, the purity is 99.67%, and the other indexes all reach the national standard of battery grade lithium carbonate.
It is worth noting that when the gas flow rate reached 0.2L/min per gram of lithium, the additive still had 26.7% reduction in the time to reach the carbonization end point, but the gas flow rate was faster, resulting in a significant reduction in the time of carbon dioxide contact with the solution, and as a result, the carbon dioxide utilization was inferior to that of examples 1, 3 and 4.
Comparative example 1:
technical LiOH H was prepared using the process scheme shown in FIG. 1 2 O (LiOH content: 56.6%) and industrial pure water were prepared into a lithium hydroxide solution having a lithium content of 30g/L, wherein 2L of the solution was taken to be added with 0.5g of sodium dodecyl sulfate additive, and the group g was taken, and the other 2L of the solution was not added with additive, and the group h was taken. g. And (h) after the two groups are subjected to microporous filtration with the pore diameter of 0.5 mu m, introducing carbon dioxide into the two groups at the constant temperature of 50 ℃ respectively, wherein the air flow speed is 1L/min, and the generation of bubbles in the groups g and h is less. The solution in group g needs to react for 128min when the pH value reaches 10, a large amount of white precipitate is generated, and carbonization is finished. The solution in the group h needs to react for 130min when reaching the pH value of 10, a large amount of white precipitate is generated, and carbonization is finished. The two groups of suspension liquid are respectively centrifugally filtered, washed and dried to obtain two groups of lithium carbonate, and the g group of lithium carbonate is used for testing the granularity D 50 Test particle size D for lithium carbonate group h 32 μm 50 74 μm. The results show that when the carbon dioxide feed rate was reduced to 0.017L/min per gram of lithium, the addition of sodium dodecyl sulfate additive did not significantly shorten the time to the carbonization end point, but the initial particle size of the dried lithium carbonate could be reduced.
Compared with examples 1-4, the results show that foaming additives such as sodium dodecyl sulfate and the like can generate a large amount of bubbles under the condition of high air flow speed, and the carbonization time is obviously shortened, but the bubbles during the reaction cannot be obviously increased at low air flow speed, and the carbonization time cannot be obviously shortened. In addition, the surfactant is attached to the surface of the product, so that agglomeration of lithium carbonate is prevented, and the added surfactant has the effect of reducing the particle size.
Comparative example 2:
technical LiOH H was prepared using the process scheme shown in FIG. 1 2 The solution of O (LiOH content 56.6%) and industrial pure water was prepared into a solution of lithium hydroxide 4L having a lithium content of 20g/L, 2L of which was taken to add 0.5g of sodium dodecyl sulfate additive asGroup i, the other 2L solution was free of additives and was group j. i. After the two groups j are subjected to microporous filtration with the aperture of 0.5 mu m, carbon dioxide is respectively introduced into the two groups j under the constant temperature condition of 50 ℃, the air flow speed is 3L/min, the number of bubbles generated by the groups i is obviously more than that of the groups j, and the obvious phenomenon of carbon dioxide escape and waste exists in the reaction of the groups i. The solution in group i needs to react for 32min when the pH value reaches 10, a large amount of white precipitate is generated, and carbonization is finished. The solution in the group j needs to react for 28min when reaching the pH value of 10, a large amount of white precipitate is generated, and carbonization is finished. The two groups of suspension liquid are respectively centrifugally filtered, washed and dried to obtain two groups of lithium carbonate, and the i groups of lithium carbonate have the test granularity D 50 26 μm, group j lithium carbonate test particle size D 50 65 μm.
The result shows that when the lithium content of the solution is 20g/L, the additive does not have the effect of shortening the carbonization time any more when the high-flow carbon dioxide is introduced, because the gas-liquid mass transfer of the carbon dioxide is not a rate control step any more under the condition of the lithium concentration, when the high-flow carbon dioxide is introduced, the carbon dioxide does not react with lithium hydroxide in the solution to generate lithium carbonate, so that the waste of the carbon dioxide is caused, and the existence of the additive can increase the bubble amount, so that a large amount of bubbles generated at the position can not shorten the reaction time, but can cause more escape of the carbon dioxide to reduce the reaction efficiency. In view of productivity, the lithium content should be as high as possible, and in the embodiment of the present application, the lithium content of the lithium hydroxide solution of the present application is preferably 25 to 35g/L because a solution with a low lithium content causes a large amount of bubbles generated during the reaction to cause a large loss of carbon dioxide.
The foregoing is merely a preferred embodiment of the present application and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present application, which are intended to be comprehended within the scope of the present application.
Claims (10)
1. A method for preparing battery grade lithium carbonate by strengthening carbonization short distance, which is characterized by comprising the following steps:
(1) Preparing lithium hydroxide solution, adding a surfactant, and performing microporous filtration to obtain refined lithium hydroxide solution;
(2) And (3) introducing industrial carbon dioxide into the refined lithium hydroxide solution at a gas flow rate of 0.03-0.3L/min per gram of lithium, performing carbonization reaction, performing solid-liquid separation and washing to obtain carbonized liquid and wet slag, and drying and crushing the wet slag to obtain the battery-grade lithium carbonate.
2. The method for preparing battery grade lithium carbonate by enhanced carbonization short-range according to claim 1, wherein the surfactant is one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate and sodium laureth sulfate; the addition amount of the surfactant is determined according to the addition amount of 0.01-0.1 g of the surfactant per gram of lithium in the solution.
3. The method for preparing battery grade lithium carbonate by enhanced carbonization short-range according to claim 1, wherein the lithium content in the lithium hydroxide solution is 25-35 g/L; the industrial grade carbon dioxide is introduced into the reactor according to the flow rate of 0.05-0.2L/min per gram of lithium.
4. The method for preparing battery grade lithium carbonate by enhanced carbonization short-range according to claim 1, wherein in the step (2), the temperature of the carbonization reaction is 20-80 ℃; the final pH value of the carbonization reaction is 9.5-10.5; the Li content in the carbonized liquid is 1.5-6 g/L.
5. The method for preparing battery grade lithium carbonate according to any one of claims 1 to 4, further comprising step (3), wherein the step (3) comprises: adding sodium carbonate into the carbonized liquid, carrying out solid-liquid separation after full reaction to obtain lithium carbonate, adding sodium phosphate into the liquid obtained by the solid-liquid separation, carrying out solid-liquid separation after full reaction to obtain lithium phosphate, adding calcium salt into the solution obtained by the solid-liquid separation, and reacting to obtain calcium slag and phosphorus-precipitating liquid.
6. The method for preparing battery grade lithium carbonate by enhanced carbonization short-range according to claim 5, wherein the addition amount of sodium carbonate is 1.05-1.1 times of the theoretical lithium precipitation amount;
the adding amount of the sodium phosphate is 1.05 to 1.1 times of the theoretical lithium precipitation amount; the calcium salt is calcium oxide and/or calcium hydroxide, and the dosage of the calcium salt is 1.05-1.1 times of the theoretical phosphorus precipitation dosage.
7. The method for preparing battery grade lithium carbonate by enhanced carbonization short-range according to claim 5, wherein the calcium slag is used as a building filler, and the post-phosphorus precipitation solution can be recycled as a mother solution.
8. The method for preparing battery grade lithium carbonate by enhanced carbonization short-range according to claim 5, wherein in the step (3), the solid-liquid separation is centrifugal filtration.
9. The method for preparing battery grade lithium carbonate by enhanced carbonization short-range according to any one of claims 1 to 4, wherein the lithium hydroxide solution is prepared by lithium hydroxide and water; the lithium hydroxide is one or more of battery-grade lithium hydroxide monohydrate, battery-grade anhydrous lithium hydroxide, industrial-grade lithium hydroxide monohydrate and industrial-grade anhydrous lithium hydroxide, and the water is clear water or industrial pure water.
10. The method for preparing battery grade lithium carbonate by enhanced carbonization short-range according to any one of claims 1 to 4, wherein in the step (2), carbon dioxide escaping during the carbonization process is collected to a storage tank through a pipeline, compressed and purified for recycling;
in the step (2), the solid-liquid separation is centrifugal filtration.
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| CN118993002A (en) * | 2024-08-14 | 2024-11-22 | 紫金矿业集团股份有限公司 | Method for directionally separating and recovering lithium sodium in lithium hydroxide evaporation mother liquor |
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|---|---|---|---|---|
| CN118993002A (en) * | 2024-08-14 | 2024-11-22 | 紫金矿业集团股份有限公司 | Method for directionally separating and recovering lithium sodium in lithium hydroxide evaporation mother liquor |
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