Method for preparing battery grade lithium carbonate from sulfate type fluorine-containing brine

Abstract

The invention relates to a method for preparing battery-grade lithium carbonate from sulfate type fluorine-containing brine. The method comprises the following steps: step 1, pretreating the brine; 2, calcium salt is added for preliminary fluorine removal; 3, removing impurities from the brine through calcium and magnesium removal resin; step 4, removing impurities from the brine through fluorine removal resin; and 5, adding a saturated sodium carbonate solution into the brine, and heating to prepare lithium carbonate. Through reasonable arrangement, the problems that the adsorption effect is poor and the cost is high when the sulfate type brine is directly subjected to adsorption lithium extraction through an existing adsorption method are solved; the method is green, environment-friendly and pollution-free, no bad substance is generated in the production process, the process is simple, the used resin can be regenerated and reused, and the cost is low; and the production and processing requirements can be met.

Description

Technical Field

[0001] The present invention relates to the field of preparation of battery-grade lithium carbonate, and particularly to a process method for preparing battery-grade lithium carbonate from sulfate-type brine. Background Art

[0002] With the rapid development of the lithium battery industry, the industrial demand for lithium has gradually increased, and lithium mainly exists in minerals and inorganic salts in nature. At present, the main production processes in domestic salt lakes are mainly adsorption method and membrane method, which have the advantages of high lithium extraction efficiency, low impurities, low cost and environmental protection. However, the adsorption method mainly targets chloride-type brine. For sulfate-type brine, if direct lithium extraction by adsorption is carried out, the effect will be greatly reduced because sulfate has a great influence on the adsorption capacity of the adsorbent, which will cause the attenuation of the adsorption capacity of the adsorbent, thus increasing the cost and making it difficult to be applied industrially. Therefore, for sulfate-type brine, the present invention provides a method for preparing battery-grade lithium carbonate from sulfate-type fluorine-containing brine, which has simple process, low cost, is green and environmentally friendly, and meets the requirements of future industrial production. Summary of the Invention

[0003] Based on this, in order to solve the above problems, it is necessary to provide a method for preparing battery-grade lithium carbonate from sulfate-type fluorine-containing brine, including the following steps:

[0004] Step 1: Pretreat the brine. The lithium content in the brine is 9356 ppm, the sodium content is 31443 ppm, the calcium content is 12 ppm, the magnesium content is 3 ppm, the fluorine content is 750 ppm, and the sulfate content is 31965 ppm. This brine is sulfate-type brine and contains relatively many impurity elements such as calcium, magnesium and fluorine.

[0005] Step 2: Add an appropriate amount of calcium salt to the pretreated brine to generate calcium fluoride precipitate for preliminary defluorination.

[0006] Step 3: First activate the cation resin for removing calcium and magnesium, then pass the brine after preliminary defluorination in Step 2 through the activated cation resin column and perform multiple recirculations. After several recirculations, the calcium and magnesium ions in the brine gradually decrease.

[0007] Step 4: Precisely filter the brine after removing calcium and magnesium in Step 3 to remove insoluble impurities in the brine.

[0008] Step 5: First activate the anion resin for defluorination, then pass the brine treated in Step 4 through the anion resin for defluorination and perform multiple recirculations. After several recirculations, the fluorine ion content in the brine gradually decreases.

[0009] Step 6: Precisely filter the resin after defluorination in Step 5 to remove insoluble impurities in the brine.

[0010] Step 7: Add saturated sodium carbonate solution into the brine processed in Step 6, and heat and stir to react to generate lithium carbonate;

[0011] Step 8: Perform solid-liquid separation on the lithium carbonate after the reaction in Step 7. The crude lithium carbonate is subjected to subsequent steps, and the mother liquor from lithium precipitation is used for subsequent preparation of lithium phosphate and production of lithium phosphate by-products;

[0012] Step 9: Add an appropriate amount of hot water to the crude lithium carbonate produced in Step 8 and wash it twice to remove soluble impurities such as sodium sulfate in the lithium carbonate;

[0013] Step 10: Centrifuge the lithium carbonate washed in Step 8 to separate the lithium carbonate from the washing liquid. The washing liquid can be used for the preparation of lithium phosphate or heated and concentrated and returned to the production line for the preparation of lithium carbonate;

[0014] In one of the embodiments, the brine in Step 1 is pretreated, and insoluble impurities are removed by adsorption and precision filtration.

[0015] In one of the embodiments, an appropriate amount of calcium salt is added in Step 2. The calcium salt should be one of calcium hydroxide and calcium oxide, and the addition amount of calcium hydroxide should be 1.6 times the fluoride ion content. After preliminary defluorination, the fluoride ion content in the brine is reduced to 30 ppm;

[0016] In one of the embodiments, the cation resin for calcium and magnesium removal in Step 3 is a calcium and magnesium chelating resin. After passing through the resin multiple times, the calcium and magnesium ion contents in the brine are reduced to less than 1 ppm;

[0017] In one of the embodiments, after passing through the resin multiple times in Step 5, the fluoride ion content in the brine is reduced to less than 1 ppm;

[0018] In one of the embodiments, the amount of saturated sodium carbonate solution added in Step 7 is 1.3 times the theoretical amount, the heating temperature is 96 °C, and the reaction time is 2 h;

[0019] In one of the embodiments, in Step 9, hot water washing is performed, wherein the addition amount of hot water is added according to a ratio of 1:3 of the solid mass, and the number of hot water washing times is at least twice;

[0020] The above method for preparing battery-grade lithium carbonate from sulfate-type fluorine-containing brine solves the problems of poor adsorption effect and high cost in directly adsorbing and extracting lithium from sulfate-type brine by the current adsorption method through reasonable settings; moreover, this application is green, environmentally friendly and pollution-free, no harmful substances are generated during the production process, the process is simple, the resin used can be regenerated and reused, and the cost is low; it can meet the production and processing requirements. Description of the Drawings

[0021] Figure 1 This is a schematic diagram of the overall process flow of the present invention. Detailed implementation manners

[0022] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following provides a detailed description of the specific implementation manners of the present invention. Many specific details are set forth in the following description to facilitate a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0023] As used herein, the term "prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variation thereof used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus containing the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0024] When an equivalent, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, it should be understood that all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value are specifically disclosed, regardless of whether the ranges are separately disclosed. For example, when the range "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range.

[0025] Furthermore, the indefinite articles "a" and "an" before an element or component of the present invention do not limit the number requirement (i.e., the number of occurrences) of the element or component. Therefore, "a" or "an" should be interpreted to include one or at least one, and the singular form of an element or component also includes the plural form, unless the number clearly refers to the singular form.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific implementation manners and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0027] Example 1

[0028] Step 1: Precisely filter the brine from Party 1. The lithium content in the brine is 9201 ppm, the sodium content is 32104 ppm, the calcium content is 15 ppm, the magnesium content is 1 ppm, the fluorine content is 745 ppm, and the sulfate content is 32156 ppm. This brine is a sulfate-type brine and contains relatively many impurity elements such as calcium, magnesium, and fluorine.

[0029] Step 2: Add 2.34 Kg of calcium hydroxide to the pretreated brine to form calcium fluoride precipitate for preliminary defluorination.

[0030] Step 3: First, activate the cation resin for removing calcium and magnesium, and then pass the brine after preliminary defluorination in Step 2 through the activated cation resin column. After several cycles, the calcium and magnesium ions in the brine gradually decrease to below 1 ppm.

[0031] Step 4: Precisely filter the brine after removing calcium and magnesium in Step 3 to remove the insoluble impurities in the brine.

[0032] Step 5: First, activate the anion resin for defluorination, and then pass the brine processed in Step 4 through the anion resin for defluorination. After several cycles, the fluorine ion content in the brine gradually decreases to below 1 ppm.

[0033] Step 6: Precisely filter the resin after defluorination in Step 5 to remove the insoluble impurities in the brine.

[0034] Step 7: Add 0.37 cubic meters of saturated sodium carbonate solution to the brine processed in Step 6, heat it to 96 °C, and stir and react for 2 h to generate lithium carbonate.

[0035] Step 8: Separate the solid and liquid of the lithium carbonate after the reaction in Step 7. The crude lithium carbonate is subjected to subsequent steps, and the mother liquor from lithium precipitation can be used for subsequent preparation of lithium phosphate to produce lithium phosphate by-products.

[0036] Step 9: Add an appropriate amount of hot water to the crude lithium carbonate produced in Step 8 and wash it twice to remove soluble impurities such as sodium sulfate in the lithium carbonate.

[0037] Step 10: Centrifuge the lithium carbonate after washing in Step 8 to separate the lithium carbonate and the washing liquid. The washing liquid can be used for the preparation of lithium phosphate or heated and concentrated and returned to the production line for the preparation of lithium carbonate.

[0038] Example 2

[0039] Step 1: Precisely filter the brine from Party 1. The lithium content in the brine is 8754 ppm, sodium content is 26540 ppm, calcium content is 16 ppm, magnesium content is 2 ppm, fluorine content is 680 ppm, and sulfate content is 28645 ppm. This brine is of the sulfate type and contains relatively many impurity elements such as calcium, magnesium, and fluorine.

[0040] Step 2: Add 2.13 Kg of calcium hydroxide to the pretreated brine to form calcium fluoride precipitate for preliminary defluorination.

[0041] Step 3: First, activate the cation resin for removing calcium and magnesium, and then pass the brine after preliminary defluorination in Step 2 through the activated cation resin column. After several cycles, the calcium and magnesium ions in the brine gradually decrease to below 1 ppm.

[0042] Step 4: Precisely filter the brine after removing calcium and magnesium in Step 3 to remove insoluble impurities in the brine.

[0043] Step 5: First, activate the anion resin for defluorination, and then pass the brine processed in Step 4 through the defluorination anion resin. After several cycles, the fluorine ion content in the brine gradually decreases to below 1 ppm.

[0044] Step 6: Precisely filter the resin after defluorination in Step 5 to remove insoluble impurities in the brine.

[0045] Step 7: Add 0.35 cubic meters of saturated sodium carbonate solution to the brine processed in Step 6, heat it to 96 °C, and stir and react for 2 h to produce lithium carbonate.

[0046] Step 8: Separate the solid and liquid of the lithium carbonate after the reaction in Step 7. The crude lithium carbonate goes through subsequent steps, and the mother liquor from lithium precipitation can be used for subsequent preparation of lithium phosphate to produce lithium phosphate by-products.

[0047] Step 9: Add an appropriate amount of hot water to the crude lithium carbonate produced in Step 8 and wash it twice to remove soluble impurities such as sodium sulfate in the lithium carbonate.

[0048] Step 10: Centrifuge the lithium carbonate after washing in Step 8 to separate the lithium carbonate and the washing liquid. The washing liquid can be used for the preparation of lithium phosphate or heated and concentrated to return to the production line for the preparation of lithium carbonate.

[0049] Table 1 Partial Element Analysis Results of Lithium Carbonate Finished Product

[0050]

[0051] As can be seen from Table 1, the lithium carbonate prepared according to the method for preparing battery-grade lithium carbonate from a sulfate-type fluorine-containing brine of the present invention meets the industry standards for battery-grade lithium carbonate.

[0052] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as falling within the scope described in this specification.

[0053] The above-described embodiments merely represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed. However, it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent shall be subject to the appended claims.

Claims

1. A method for preparing battery-grade lithium carbonate from sulfate-type fluorine-containing brine, characterized in that: The following steps are involved: Step 1: pretreat the brine. The lithium content in the brine is 9356ppm, the sodium content is 31443ppm, the calcium content is 12ppm, the magnesium content is 3ppm, the fluorine content is 750ppm, and the sulfate content is 31965ppm. The brine is sulfate brine and contains more impurity elements such as calcium, magnesium and fluorine. Step 2: Add an appropriate amount of calcium salt to the pretreated brine to generate calcium fluoride precipitation for preliminary defluorination; Step 3: First, activate the cationic resin for removing calcium and magnesium, then pass the brine after preliminary defluorination in step 2 through the activated cationic resin column and cycle for multiple times; Step 4: finely filter the brine after removing calcium and magnesium in step 3 to remove insoluble impurities in the brine; Step 5: First, the defluoridation anion resin is activated, and then the brine treated in step 4 is passed through the defluoridation anion resin and circulated for multiple times; Step 6: The resin after defluorination in step 5 is subjected to precise filtration to remove the incompatible impurities in the brine; Step 7: adding saturated sodium carbonate solution to the brine treated in step 6, heating and stirring to react to generate lithium carbonate; Step 8: performing solid-liquid separation on the lithium carbonate after the reaction in step 7, and performing subsequent steps on the crude lithium carbonate; Step 9: Add an appropriate amount of hot water to the crude lithium carbonate produced in step 8 and wash it twice to remove soluble impurities such as sodium sulfate in the carbonate; Step 10: Centrifuge the lithium carbonate washed in step 8 to separate the lithium carbonate and the washing liquid.

2. The method for preparing battery-grade lithium carbonate from sulfate-type fluorine-containing brine according to claim 1, characterized in that: In the step 1, the brine is pretreated by adsorption and precision filtration to remove insoluble impurities.

3. The method for preparing battery-grade lithium carbonate from sulfate-type fluorine-containing brine according to claim 1, characterized in that: In the step 2, a proper amount of calcium salt is added. The calcium salt should be one of calcium hydroxide and calcium oxide. The amount of calcium hydroxide added should be 1.6 times the fluoride ion content. After preliminary defluorination, the fluoride ion content in the brine is reduced to 30 ppm.

4. The method for preparing battery-grade lithium carbonate from sulfate-type fluorine-containing brine according to claim 1, characterized in that: The cationic resin for removing calcium and magnesium in step three is a calcium and magnesium removing chelating resin. After multiple passes through the resin, the calcium and magnesium ion content in the brine is reduced to less than 1 ppm.

5. The method for preparing battery-grade lithium carbonate from sulfate-type fluorine-containing brine according to claim 1, characterized in that: In the step 5, after multiple resin passes, the fluoride ion content in the brine is reduced to less than 1 ppm.

6. The method for preparing battery-grade lithium carbonate from sulfate-type fluorine-containing brine according to claim 1, characterized in that: The amount of saturated sodium carbonate solution added in step 7 is 1.3 times the theoretical amount, the heating temperature is 96° C., and the reaction time is 2 h.

7. The method for preparing battery-grade lithium carbonate from sulfate-type fluorine-containing brine according to claim 1, characterized in that: In the step nine, hot water washing is performed, wherein the amount of hot water added is 1:3 of the solid mass, and the hot water washing is performed at least twice.

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