Method for comprehensive recovery of potassium, sodium and lithium resources in lithium ore lithium extraction mother liquor

Abstract

This invention belongs to the field of chemical production technology and discloses a method for the comprehensive recovery of potassium, sodium, and lithium resources from lithium extraction mother liquor from lithium ore. The method includes the following steps: evaporating and concentrating the lithium extraction mother liquor to obtain sodium sulfate slurry, which is then separated to obtain sodium sulfate product and concentrated mother liquor; cooling the concentrated mother liquor to obtain cold precipitated salt and cold precipitated mother liquor; mixing the cold precipitated mother liquor with a soda ash solution to precipitate lithium to obtain lithium carbonate product and lithium precipitation mother liquor; mixing the cold precipitated salt with water to obtain a cold precipitated salt solution, evaporating and concentrating the precipitated salt to obtain hot precipitated salt; mixing the hot precipitated salt with water, heating until the solid dissolves, and cooling to obtain potassium sulfate product and potassium sulfate mother liquor. This invention utilizes the crystallization characteristics of sodium and potassium salts to efficiently separate sodium, potassium, and lithium from lithium extraction mother liquor from high-sodium, low-potassium lithium ore without adding other reagents. It can recover 99% of lithium in a single process, and the obtained sodium sulfate and potassium sulfate meet the requirements for superior products.

Description

Technical Field

[0001] This invention relates to the field of chemical production technology, and in particular to a method for the comprehensive recovery of potassium, sodium and lithium resources from lithium ore mother liquor. Background Technology

[0002] Lithium ore is a common raw material for the preparation of basic lithium salts. Batteries have a lifespan of approximately 8 years, and with the increasing number of batteries being retired in recent years, these used batteries can also be used as lithium sources. Basic lithium salt products such as lithium carbonate and lithium hydroxide are widely used in fuels, chemical raw materials, glass manufacturing, ceramics, food, semiconductors, national defense, nuclear energy, and catalysts. Lithium carbonate and lithium hydroxide can also be used as raw materials for the preparation of other lithium salt products. With continuous innovation and development in lithium salt materials, they are being applied in various fields, and the market demand for lithium materials is growing daily.

[0003] Lithium extraction by roasting and water leaching of lithium sulfate is widely used in lithium ore and lithium extraction from waste batteries. The lithium extraction residue contains high levels of sodium and potassium as well as a small amount of lithium. In recent years, with social development and the awakening of environmental awareness, the comprehensive utilization of resources has become a research hotspot, and the resource utilization of lithium extraction mother liquor has become a research hotspot.

[0004] Patent CN105174290A discloses a process for separating sodium and potassium salts. This process involves heating and concentrating sodium chloride to precipitate it, and then cooling and precipitating potassium chloride. However, the product obtained by this method has a low purity.

[0005] Patent CN116462262A discloses a resource recovery process for high-salinity wastewater from the lithium industry. This method requires the external addition of NaCl and KCl during the sodium-potassium separation process. Its main products are NaCl and K₂SO₄. Cl₂ is present in the system. - Higher content requires higher quality equipment materials.

[0006] Although the aforementioned literature discloses some methods for separating mixed salts, they still suffer from drawbacks such as high energy consumption, complex processes, and insufficient product purity. Therefore, developing a mixed salt separation method with a simple process flow, low cost, and high product purity remains of great significance. Summary of the Invention

[0007] The purpose of this invention is to provide a method for the comprehensive recovery of potassium, sodium and lithium resources from lithium ore mother liquor, solving the problems of high energy consumption, complex process and low product purity in existing mixed salt separation processes.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] This invention provides a method for the comprehensive recovery of potassium, sodium, and lithium resources from lithium extraction mother liquor from lithium ore, comprising the following steps:

[0010] The lithium extraction mother liquor from lithium ore is first evaporated and concentrated to precipitate salt, resulting in sodium sulfate slurry, which is then separated to obtain sodium sulfate product and concentrated mother liquor.

[0011] The concentrated mother liquor is cooled to precipitate salt and then separated to obtain cold precipitated salt and cold precipitated mother liquor;

[0012] The cold precipitation mother liquor is mixed with a soda ash solution to precipitate lithium, resulting in lithium carbonate product and lithium precipitation mother liquor.

[0013] The cold-precipitated salt is mixed with water to obtain a cold-precipitated salt solution, which is then concentrated by a second evaporation and separated to obtain hot-precipitated salt.

[0014] The hot salt is mixed with water and heated until the solid dissolves, then cooled first, and then separated to obtain potassium sulfate product and potassium sulfate mother liquor;

[0015] The potassium sulfate mother liquor is returned and mixed with the cold precipitated salt;

[0016] The lithium precipitation mother liquor is adjusted to neutral and then mixed with the lithium extraction mother liquor from lithium ore.

[0017] Preferably, in the above-mentioned method for comprehensive recovery of potassium, sodium and lithium resources in lithium extraction mother liquor from lithium ore, the temperature of the first evaporation and concentration is 80-110°C.

[0018] The first evaporation and concentration should be stopped when the density of the sodium sulfate slurry is 1 to 1.8 g / mL.

[0019] Preferably, in the above-mentioned method for comprehensive recovery of potassium, sodium and lithium resources in lithium ore mother liquor, the final temperature of cooling and salt precipitation is 20-28°C.

[0020] Preferably, in the above-mentioned method for comprehensive recovery of potassium, sodium and lithium resources in lithium ore mother liquor, the molar ratio of soda ash in the soda ash solution to lithium ions in the cold precipitation mother liquor is 1 to 2:1.

[0021] Preferably, in the above-mentioned method for comprehensive recovery of potassium, sodium and lithium resources in lithium ore mother liquor, the mass ratio of cold-precipitated salt to water is 1:3.5 to 4.5.

[0022] Preferably, in the above-mentioned method for comprehensive recovery of potassium, sodium and lithium resources in lithium ore mother liquor, the temperature of the second evaporation and concentration is 80-110°C.

[0023] The second evaporation and concentration should be stopped when the density of the cold salt solution is 1 to 1.8 g / mL.

[0024] Preferably, in the above-mentioned method for comprehensive recovery of potassium, sodium and lithium resources in lithium ore mother liquor, the mass ratio of thermally precipitated salt to water is 1:3.6-5.

[0025] Preferably, in the above-mentioned method for comprehensive recovery of potassium, sodium and lithium resources in lithium ore mother liquor, the final temperature of the first cooling is 20-30°C.

[0026] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0027] This invention utilizes the relationship between the solubility of sodium and potassium salts and temperature, as well as their crystallization patterns in phase diagrams. The crystallization phase diagrams of potassium sulfate and sodium sulfate are shown below. Figure 2 As shown, after the lithium extraction mother liquor from lithium ore is evaporated and concentrated, the solvent continuously evaporates, and the ion concentration in the system continuously increases. First, it reaches the sodium sulfate saturation state, and sodium sulfate precipitates out, followed by potassium sulfate. Without adding other chemicals, lithium, sodium, and potassium in the lithium extraction mother liquor can be efficiently separated through a simple process. About 85% of the potassium in the solution precipitates out as salt, and the total lithium loss during the separation process is about 0.1%. 99% of the lithium can be recovered in a single process, producing high-value-added industrial-grade lithium carbonate, high-quality sodium sulfate, and high-quality potassium sulfate products. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0029] Figure 1 This is a process flow diagram of the present invention;

[0030] Figure 2 This is a crystallographic phase diagram of potassium sulfate and sodium sulfate. Detailed Implementation

[0031] A method for comprehensive recovery of potassium, sodium, and lithium resources from lithium extraction mother liquor from lithium ore includes the following steps:

[0032] The lithium extraction mother liquor from lithium ore is first evaporated and concentrated to precipitate salt, resulting in sodium sulfate slurry, which is then separated to obtain sodium sulfate product and concentrated mother liquor.

[0033] The concentrated mother liquor is cooled to precipitate salt and then separated to obtain cold precipitated salt and cold precipitated mother liquor;

[0034] The cold precipitation mother liquor is mixed with a soda ash solution to precipitate lithium, resulting in lithium carbonate product and lithium precipitation mother liquor.

[0035] The cold-precipitated salt is mixed with water to obtain a cold-precipitated salt solution, which is then concentrated by a second evaporation and separated to obtain hot-precipitated salt.

[0036] The hot salt is mixed with water and heated until the solid dissolves, then cooled first, and then separated to obtain potassium sulfate product and potassium sulfate mother liquor;

[0037] The potassium sulfate mother liquor is returned and mixed with the cold precipitated salt;

[0038] The lithium precipitation mother liquor is adjusted to neutral and then mixed with the lithium extraction mother liquor from lithium ore.

[0039] In this invention, the temperature of the first evaporation and concentration is preferably 80-110°C, more preferably 85-105°C, and even more preferably 90-100°C;

[0040] The first evaporation and concentration is stopped when the density of the sodium sulfate slurry is preferably 1 to 1.8 g / mL, more preferably 1.2 to 1.6 g / mL, and even more preferably 1.4 to 1.5 g / mL.

[0041] In this invention, the specific process of obtaining sodium sulfate product and concentrated mother liquor by separation is as follows: sodium sulfate wet material and concentrated mother liquor are obtained by centrifugation, and the sodium sulfate wet material is dried to obtain sodium sulfate product.

[0042] In this invention, the final temperature of the cooling salt precipitation is preferably 20-28°C, more preferably 22-26°C, and even more preferably 23-25°C.

[0043] In this invention, the molar ratio of soda ash in the soda ash solution to lithium ions in the cold precipitation mother liquor is preferably 1 to 2:1, more preferably 1.2 to 1.8:1, and even more preferably 1.4 to 1.5:1.

[0044] In this invention, the concentration of the soda ash solution is preferably 210-230 g / L, more preferably 215-225 g / L, and even more preferably 218-220 g / L.

[0045] In this invention, the specific process of obtaining lithium carbonate product and lithium precipitation mother liquor by lithium precipitation is as follows: lithium carbonate wet material and lithium precipitation mother liquor are obtained by lithium precipitation, and the lithium carbonate wet material is dried to obtain lithium carbonate product.

[0046] In this invention, the mass ratio of the cold-precipitated salt to water is preferably 1:3.5 to 4.5, more preferably 1:3.8 to 4.2, and even more preferably 1:4.

[0047] In this invention, the cold-precipitated salt and the water in the water are preferably secondary steam condensate, which can save water resources.

[0048] In this invention, the temperature of the second evaporation and concentration is preferably 80-110°C, more preferably 85-105°C, and even more preferably 90-110°C;

[0049] The second evaporation and concentration is stopped when the density of the cold-precipitated salt solution is preferably 1 to 1.8 g / mL, more preferably 1.2 to 1.6 g / mL, and even more preferably 1.3 to 1.5 g / mL.

[0050] In this invention, the mass ratio of the pyrolysis salt to water is preferably 1:3.6 to 5, more preferably 1:4 to 4.8, and even more preferably 1:4.2 to 4.5.

[0051] In this invention, the water in the pyrolysis salt and water is preferably secondary steam condensate, which can save water resources.

[0052] In this invention, the final temperature of the first cooling is preferably 20-30°C, more preferably 22-28°C, and even more preferably 24-26°C.

[0053] In this invention, the specific process for separating the potassium sulfate product and the potassium sulfate mother liquor is as follows:

[0054] Potassium sulfate wet material and potassium sulfate mother liquor were obtained by centrifugation. The potassium sulfate wet material was dried to obtain potassium sulfate product.

[0055] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] The specific components of the lithium ore lithium extraction mother liquor in the following embodiments are shown in Table 1.

[0057] Table 1. Components of lithium extraction mother liquor from lithium ore

[0058] Test Project <![CDATA[Li + ]]> <![CDATA[Na + ]]> <![CDATA[K + ]]> <![CDATA[SO4 2- ]]> Lithium extraction mother liquor from lithium ore (g / L) 3.29 68.22 22.27 189.72

[0059] Example 1

[0060] This invention provides a method for the comprehensive recovery of potassium, sodium, and lithium resources from lithium extraction mother liquor from lithium ore, comprising the following steps:

[0061] 4L of lithium ore mother liquor was evaporated and concentrated at 100℃ until the solution density was 1.2g / mL. Evaporation was stopped and the solution was separated by centrifugation while hot to obtain 187.1g of wet sodium sulfate and 1.8L of concentrated mother liquor. The wet sodium sulfate was dried to obtain sodium sulfate product.

[0062] The concentrated mother liquor was cooled to 26°C and centrifuged to obtain 51.5g of cold-precipitated salt and 1.76L of cold-precipitated mother liquor;

[0063] 1.76 L of cold precipitation mother liquor was mixed with 210 g / L soda ash solution (the molar ratio of soda ash to lithium ions in the cold precipitation mother liquor was 1.08:1) to precipitate lithium, yielding 62.53 g of wet lithium carbonate and 1.8 L of precipitation mother liquor. The precipitation mother liquor was adjusted to neutral and then mixed with lithium ore extraction mother liquor. The wet lithium carbonate was dried to obtain the lithium carbonate product.

[0064] 51.5g of cold-precipitated salt was mixed with secondary steam condensate at a mass ratio of 1:4 to obtain a cold-precipitated salt solution. The solution was then concentrated by evaporation at 100℃ until the density of the cold-precipitated salt solution reached 1.5g / mL. After solid-liquid separation, 38.6g of hot-precipitated salt was obtained.

[0065] The hot-precipitated salt and secondary steam condensate were mixed at a mass ratio of 1:5, heated until the solid dissolved, and then cooled to 30°C. After centrifugation, 15g of wet potassium sulfate and 0.18L of potassium sulfate mother liquor were obtained. The wet potassium sulfate was dried to obtain the potassium sulfate product. The potassium sulfate mother liquor was returned to be mixed with the cold-precipitated salt.

[0066] The specific components of sodium sulfate products, cold-precipitated salts, and cold-precipitated mother liquor are shown in Table 2.

[0067] Table 2. Components of wet sodium sulfate, cold-precipitated salt, and cold-precipitated mother liquor.

[0068]

[0069]

[0070] The specific components of the wet lithium carbonate feedstock and the lithium precipitation mother liquor are shown in Table 3.

[0071] Table 3. Components of wet lithium carbonate feed and lithium precipitation mother liquor

[0072] Test Project <![CDATA[Li + ]]> <![CDATA[Na + ]]> <![CDATA[K + ]]> <![CDATA[SO4 2- ]]> <![CDATA[CO3 2- ]]> Lithium carbonate wet material (%) 16.72 0.21 0.19 0.046 68.15 Lithium precipitation mother liquor (g / L) 1.14 115.29 60.6 22.57 11.83

[0073] The specific components of the pyrolysis salt and potassium sulfate wet material are shown in Table 4.

[0074] Table 4. Components of pyrolyzed salt and potassium sulfate wet material

[0075] Test Project <![CDATA[Li + ]]> <![CDATA[Na + ]]> <![CDATA[K + ]]> <![CDATA[SO4 2- ]]> Heat-exposed salt (%) 0.025 7.48 36.02 48.61 Potassium sulfate wet material (%) ND 0.48 44.24 54.38

[0076] Example 2

[0077] This invention provides a method for the comprehensive recovery of potassium, sodium, and lithium resources from lithium extraction mother liquor from lithium ore, comprising the following steps:

[0078] 4L of lithium ore mother liquor was evaporated and concentrated at 90℃ until the solution density was 1.25g / mL. Evaporation was stopped, and the solution was separated by centrifugation while hot to obtain 177.5g of wet sodium sulfate and 1.9L of concentrated mother liquor. The wet sodium sulfate was dried to obtain sodium sulfate product.

[0079] The concentrated mother liquor was cooled to 23°C and centrifuged to obtain 48.9g of cold-precipitated salt and 1.85L of cold-precipitated mother liquor;

[0080] 1.85 L of cold precipitation mother liquor was mixed with 210 g / L soda ash solution (the molar ratio of soda ash in the soda ash solution to lithium ions in the cold precipitation mother liquor was 1.05:1) to precipitate lithium, yielding 63 g of wet lithium carbonate and 1.9 L of lithium precipitation mother liquor; the lithium precipitation mother liquor was adjusted to neutral and then mixed with lithium ore extraction mother liquor, and the wet lithium carbonate was dried to obtain lithium carbonate product;

[0081] 48.9g of cold-precipitated salt was mixed with secondary steam condensate at a mass ratio of 1:4.5 to obtain a cold-precipitated salt solution. The solution was then concentrated by evaporation at 110℃ until the density of the cold-precipitated salt solution reached 1.5g / mL. After solid-liquid separation, 35.7g of hot-precipitated salt was obtained.

[0082] The hot-precipitated salt and secondary steam condensate were mixed at a mass ratio of 1:4, heated until the solid dissolved, and then cooled to 30°C. After centrifugation, 14.6g of potassium sulfate wet material and 0.16L of potassium sulfate mother liquor were obtained. The potassium sulfate mother liquor was returned to be mixed with the cold-precipitated salt, and the potassium sulfate wet material was dried to obtain the potassium sulfate product.

[0083] The specific components of sodium sulfate products, cold-precipitated salts, and cold-precipitated mother liquor are shown in Table 5.

[0084] Table 5. Components of wet sodium sulfate, cold-precipitated salt, and cold-precipitated mother liquor

[0085] Test Project <![CDATA[Li + ]]> <![CDATA[Na + ]]> <![CDATA[K + ]]> <![CDATA[SO4 2- ]]> Sodium sulfate wet material (%) 0.01 30.49 0.75 67.19 Cold-precipitated salt (%) 0.087 10.23 30.12 55.99 Cold precipitation mother liquor (g / L) 7.23 107.6 40.71 333.24

[0086] The specific components of the wet lithium carbonate feedstock and the lithium precipitation mother liquor are shown in Table 6.

[0087] Table 6. Components of wet lithium carbonate feed and lithium precipitation mother liquor

[0088] Test Project <![CDATA[Li + ]]> <![CDATA[Na + ]]> <![CDATA[K + ]]> <![CDATA[SO4 2- ]]> <![CDATA[CO3 2- ]]> Lithium carbonate wet material (%) 16.77 0.36 0.15 0.05 69.19 Lithium precipitation mother liquor (g / L) 1.17 83.43 30.76 21.59 7.97

[0089] The specific components of the pyrolysis salt and potassium sulfate wet material are shown in Table 7.

[0090] Table 7 Composition of pyrolysis salt and potassium sulfate wet material

[0091] Test Project <![CDATA[Li + ]]> <![CDATA[Na + ]]> <![CDATA[K + ]]> <![CDATA[SO4 2- ]]> Heat-exposed salt (%) 0.025 7.48 32.02 36.61 Potassium sulfate wet material (%) 0.00011 0.64 44.09 52.85

[0092] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for comprehensive recovery of potassium, sodium and lithium resources in a lithium ore lithium extraction mother liquor, characterized in that, Includes the following steps: The lithium extraction mother liquor from lithium ore undergoes a first evaporation and concentration process to precipitate salt, yielding a sodium sulfate slurry. This slurry is then separated to obtain sodium sulfate product and concentrated mother liquor. The temperature of the first evaporation and concentration process is 80–110°C. The first evaporation and concentration process is stopped when the density of the sodium sulfate slurry reaches 1–1.8 g / mL. The concentrated mother liquor is cooled and precipitated to obtain cold precipitated salt and cold precipitated mother liquor; the final temperature of the cooled precipitated salt is 20-28℃. The cold precipitation mother liquor is mixed with a soda ash solution to precipitate lithium, resulting in lithium carbonate product and lithium precipitation mother liquor. The cold-precipitated salt is mixed with water to obtain a cold-precipitated salt solution, which is then subjected to a second evaporation to concentrate the salt, and then separated to obtain a hot-precipitated salt; the temperature of the second evaporation and concentration is 80-110℃; the second evaporation and concentration is stopped when the density of the cold-precipitated salt solution is 1-1.8 g / mL; The hot salt is mixed with water and heated until the solid dissolves, then subjected to a first cooling, and then separated to obtain potassium sulfate product and potassium sulfate mother liquor; the final temperature of the first cooling is 20-30℃. The potassium sulfate mother liquor is returned and mixed with the cold precipitated salt; The lithium precipitation mother liquor is adjusted to neutral and then mixed with the lithium extraction mother liquor from lithium ore.

2. The method for comprehensive recovery of potassium, sodium and lithium resources in lithium ore lithium extraction mother liquor according to claim 1, characterized in that, The molar ratio of soda ash to lithium ions in the cold precipitation mother liquor in the soda ash solution is 1 to 2:

1.

3. The method for comprehensive recovery of potassium, sodium, and lithium resources from lithium ore mother liquor according to claim 1 or 2, characterized in that, The mass ratio of the cold-precipitated salt to water is 1:3.5 to 4.

5.

4. The method for comprehensive recovery of potassium, sodium, and lithium resources from lithium ore mother liquor according to claim 1, characterized in that, The mass ratio of the pyrolysis salt to water is 1:3.6 to 5.

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