Method for co-production of lithium and potassium in salt lake brine

Abstract

The invention belongs to the field of salt lake resource extraction, and particularly relates to a salt lake brine lithium and potassium co-production method. The method comprises the following steps: firstly, mixing an aluminum lithium extraction desorption agent with salt lake brine to complete lithium extraction; then, the sulfate radicals on the lithium extraction desorption agent are eluted with the regeneration solution; lithium in the lithium extraction adsorbent is desorbed by a desorbing agent to obtain lithium-rich qualified liquid, and a lithium salt product is obtained after concentration and impurity removal through reverse osmosis, nanofiltration and the like; washing sulfate radicals in the regenerated liquid through cyclic regeneration, gradually increasing the content of the sulfate radicals, and separating out sodium sulfate through freezing crystallization; adsorbing potassium ions by the adsorbed tail brine through a potassium extraction material; and performing desorption by using sodium sulfate to obtain a potassium-rich solution, evaporating to obtain crude potassium sulfate, and performing salt leaching and drying to obtain the product potassium sulfate. According to the method, lithium and potassium are extracted through the lithium extraction adsorbent and the potassium extraction material respectively, analysis of the potassium extraction process is carried out through the byproduct sodium sulfate of the lithium extraction regeneration process, comprehensive resource utilization of lithium and potassium in the salt lake brine is achieved, and the method has good industrialization prospects.

Description

Technical Field

[0001] This invention relates to a method for the co-production of lithium and potassium from salt lake brine, belonging to the field of salt lake resource extraction. Background Technology

[0002] Potassium is an important salt lake resource, widely used in medicine, petrochemicals, and agriculture, and is a vital fertilizer resource for national agriculture. Lithium is the lightest metallic element in nature, widely used in emerging fields such as battery industry, glass industry, ceramics industry, lubricants, aluminum smelting industry, pharmaceuticals, refrigerants, nuclear industry, and optoelectronics, and has extremely high strategic value.

[0003] In recent years, my country has placed increasing emphasis on the exploitation of salt lake resources. On the one hand, my country is rich in salt lake resources; on the other hand, the exploitation of salt lakes has long been too one-sided, often focusing on the exploitation of only one element, resulting in the underutilization of the tailings brine. Therefore, the coordinated exploitation of multiple resources to achieve comprehensive resource utilization is more in line with the direction of national strategic development.

[0004] Chinese patent application CN119240756A discloses a method for lithium extraction from sulfate-containing brine. However, high sulfate levels can lead to poisoning of aluminum-based adsorbents. The adsorbent's adsorption capacity is restored through chloride regeneration. This method typically uses sodium chloride as the regenerator. After regeneration, the sulfate content in the regenerator increases rapidly. The sodium sulfate can be eluted out by freeze crystallization or nanofiltration. The eluted sodium sulfate-based mixed salt is often wasted, and the adsorbed tail brine is often discharged back into the lake, resulting in waste.

[0005] Furthermore, in existing technologies, lithium and potassium are generally extracted separately. Lithium extraction is generally accomplished using adsorption and concentration methods, while potassium extraction is generally accomplished using the method of sun-drying salt fields. Currently, there is no research on the combined extraction of lithium and potassium. Therefore, there is an urgent need to provide a method for the co-production of lithium and potassium from salt lake brine to achieve a more comprehensive and efficient utilization of salt lake resources. Summary of the Invention

[0006] This invention provides a method for the co-production of lithium and potassium from salt lake brine. By combining a lithium and potassium extraction process, the tail brine from the lithium extraction process is used for potassium extraction, and the sodium sulfate eluted from the regenerated liquid is used as an eluent for the potassium extraction process. This method achieves increased economic benefits from the reuse of salt lake tail brine and the recycling of the regenerated liquid, thus enabling more comprehensive utilization of salt lake resources. This method has the advantages of simple process, independence from topographical factors, complementary advantages between lithium and potassium extraction processes, and reduced process costs.

[0007] The technical solution provided by this invention is as follows:

[0008] A method for co-producing lithium and potassium from salt lake brine includes the following steps:

[0009] Step 1: Mix the salt lake brine with the lithium extraction adsorbent to complete lithium extraction and obtain the tail brine after adsorption is completed;

[0010] Step 2: Use the regeneration solution to wash off the sulfate ions on the lithium extraction adsorbent;

[0011] Step 3: Use a desorption agent to desorb the lithium from the lithium extraction adsorbent to obtain a qualified lithium-rich solution, which is then concentrated and purified by membrane methods to obtain lithium salt.

[0012] Step 4: The regenerated solution is rinsed to remove sulfate ions from the poisoned lithium extraction adsorbent. The regenerated solution is recycled to gradually increase the sulfate content. Sodium sulfate is then precipitated by freeze crystallization.

[0013] Step 5: Mix the adsorbed tail brine with potassium extraction material to adsorb potassium ions.

[0014] Step 6: Use the sodium sulfate obtained in Step 4 to analyze the potassium extraction material to obtain a potassium-rich solution. Evaporate the solution to obtain crude potassium sulfate, and then wash and dry it to obtain potassium sulfate. The lithium extraction adsorbent is an aluminum-based lithium extraction adsorbent.

[0015] Furthermore, the sulfate content in the salt lake brine is greater than 10 g / L, and the ratio of chloride ions to sulfate ions is less than 5.

[0016] Furthermore, the regenerated solution is a sodium chloride solution with a sodium ion concentration of 80 g / L or higher.

[0017] Furthermore, the desorbent can be one or a mixture of pure water, tap water, industrial reverse osmosis water, and lithium-rich solution.

[0018] Furthermore, the concentration and impurity removal employs a membrane method, which can be one or a combination of nanofiltration, reverse osmosis, and electrodialysis.

[0019] Furthermore, the aluminum-based lithium extraction adsorbent is a combination of lithium chloride and aluminum chloride, namely LiAl-LDHS.

[0020] Furthermore, the potassium-extracting material can be a modified natural clinoptilolite, hydrotalcite, or potassium ferrocyanide synthetic material.

[0021] Furthermore, the lithium salt is lithium carbonate.

[0022] Furthermore, the temperature for the analysis is 85~95℃.

[0023] Furthermore, the lithium-rich qualified solution has a lithium ion concentration of 700 mg / L or higher, and the potassium-rich solution has a potassium ion concentration of 500 mg / L or higher.

[0024] Beneficial effects

[0025] This invention first involves mixing an aluminum-based lithium extraction adsorbent with brine from a salt lake to extract lithium. Then, a regenerated solution is used to wash away sulfate ions from the adsorbent. Next, a desorption agent is used to desorb the lithium from the adsorbent, yielding a lithium-rich qualified solution. This solution is then concentrated and purified using reverse osmosis and nanofiltration to obtain the final lithium salt product. The regenerated solution is circulated to wash away sulfate ions, gradually increasing the sulfate content. Sodium sulfate is then precipitated through freeze crystallization. The tail brine after adsorption is completed is then treated with a potassium extraction material to adsorb potassium ions. Sodium sulfate is used for desorption to obtain a primary potassium-rich solution, which is then evaporated to obtain crude potassium sulfate. Finally, the solution is washed and dried to obtain the final product, potassium sulfate. This invention extracts lithium and potassium separately using a lithium-extraction adsorbent and a potassium-extraction material. The lithium-extraction adsorbent maintains its adsorption and desorption performance through elution with a regeneration solution. Without a regeneration step, the adsorption performance of the adsorbent gradually decreases to about 30% of its original value. The potassium-extraction process is desorbed using sodium sulfate, a byproduct of the lithium extraction regeneration process, reducing the cost of the desorbent in the potassium extraction process. This invention is the first to jointly extract lithium and potassium, realizing the comprehensive resource utilization of lithium and potassium in salt lake brine, and has good industrialization prospects. Attached Figure Description

[0026] Figure 1 This is a flowchart of a method for co-producing lithium and potassium from salt lake brine provided in an embodiment of the present invention. Detailed Implementation

[0027] This invention relates to the comprehensive utilization and development of salt lake brine resources, specifically a method for the joint extraction of lithium and potassium from salt lake brine. First, an aluminum-based lithium-extraction adsorbent is mixed with the salt lake brine to complete lithium extraction, yielding a tail brine with complete adsorption. Then, a regenerated solution is used to wash away sulfate ions from the lithium-extraction adsorbent. Next, a descaling agent is used to desorb the lithium from the adsorbent, obtaining a lithium-rich qualified solution. This solution is then concentrated and purified using reverse osmosis and nanofiltration, and finally, lithium carbonate is obtained through precipitation. The regenerated solution is then recycled to wash away poisoned lithium-extraction adsorbent, replacing sulfate ions with chloride ions. The regenerated solution is recycled to gradually increase its sulfate content, and sodium sulfate is precipitated through freeze crystallization. The tail brine with complete adsorption is then processed by a potassium-extraction material to adsorb potassium ions. Sodium sulfate is used for descaling at 90°C to obtain a primary potassium-rich solution, which is then evaporated to obtain crude potassium sulfate. Finally, the solution is washed and dried to obtain the final product, potassium sulfate. This invention extracts lithium and potassium separately using lithium-extraction adsorbents and potassium-extraction materials. Sodium sulfate, a byproduct of the lithium extraction regeneration process, is used to analyze the potassium extraction process. This regeneration process solves the problem of adsorbent poisoning that occurs with conventional aluminum-based lithium-extraction adsorbents in sulfate-rich brine, ensuring the normal operation of the lithium extraction process. The sodium sulfate byproduct from the regeneration tail liquid is configured as an analytical agent for the potassium extraction process, thereby achieving a synergistic production effect and realizing the comprehensive resource utilization of lithium and potassium in salt lake brine, showing good industrialization prospects.

[0028] The lithium extraction adsorbent is an aluminum-based lithium extraction adsorbent, specifically a LiAl-LDHS complex formed from lithium chloride and aluminum chloride. The aluminum-based lithium extraction adsorbent uses lithium chloride and aluminum chloride as raw materials, controlling the molar ratio of lithium to aluminum to approximately 2, and employs a co-precipitation method. The reaction endpoint is controlled at pH 7 using sodium hydroxide solution titration to obtain the aluminum-based lithium extraction adsorbent. The elution process involves passing the regenerated solution through a lithium extraction adsorbent containing brine with high sulfate content. The brine has a sulfate content greater than 10 g / L and a chloride to sulfate ratio less than 5. The regenerated solution is a sodium chloride solution with a sodium ion concentration greater than 80 g / L. The eluent can be one or a mixture of pure water, tap water, industrial reverse osmosis water, and lithium-rich solutions. The concentration and impurity removal employs a membrane method, which can be one or a mixture of nanofiltration, reverse osmosis, and electrodialysis. The poisoned adsorbent is the lithium extraction adsorbent contaminated with sulfate. The potassium extraction material can be one of the following: modified natural clinoptilolite, hydrotalcite, or potassium ferrocyanide synthetic materials. The lithium salt is lithium carbonate. The desorption temperature is 85-95℃. The lithium-ion concentration of the qualified lithium-rich solution is 700 mg / L or higher, and the potassium-rich solution has a potassium-ion concentration of 500 mg / L or higher.

[0029] Example 1

[0030] The brine used in this experiment was a sulfate-type salt lake. The lithium extraction adsorbent used was an aluminum-based adsorbent, and the potassium extraction material was modified sodium-type natural clinoptilolite. The concentrations of the main ions in the brine were 0.3 g / L, 16 g / L, 2 g / L, 0.25 g / L, 2 g / L, and 0.4 g / L, respectively; the sulfate concentration was 10 g / L; and the pH of the brine was 6.2. Lithium extraction was performed on 11BV brine using 50ml (1BV) of aluminum-based adsorbent. The lithium concentration in the tail brine was reduced to 0.03g / L. The aluminum-based adsorbent was regenerated using a 20BV sodium chloride solution with a concentration of 80g / L, and then eluted using 4BV pure water. This yielded a qualified lithium-rich solution with a lithium ion concentration of 700mg / L, an adsorption capacity of 3g / L, and a elution capacity of 2.8g / L. When the sulfate concentration in the regenerated solution reached 12g / L, nanofiltration was used to remove the remaining lithium from the regenerated solution. A potassium-extraction and desorption agent was prepared by using a concentrated solution mainly composed of sodium sulfate. Potassium adsorption material (300 ml (6 BV) of sodium-type natural clinoptilolite) was then used to conduct a potassium adsorption test on 20 BV of tail brine. The potassium concentration in the tail brine was reduced to 0.4 g / L, with an adsorption capacity of 5.5 g / L and a desorption capacity of 5.2 g / L. The potassium-extraction material was then desorbed using a sodium sulfate solution with a sodium ion concentration of 90 g / L obtained by nanofiltration of the regenerated liquid at 90°C, yielding a potassium-rich qualified solution with a potassium ion concentration of 500 mg / L. The lithium-rich qualified solution was purified by reverse osmosis, electrodialysis concentration, nanofiltration, and chelation resin. The final sodium carbonate product obtained by lithium precipitation with sodium carbonate achieved a purity of 99.5%. The potassium-rich qualified solution was further purified by evaporation to precipitate sodium sulfate, increasing the potassium sulfate ratio in the mother liquor. The mother liquor was then mixed with the next potassium-rich qualified solution for further evaporation to precipitate sodium, yielding crude potassium sulfate. The crude potassium sulfate product obtained by salt washing and drying had a purity greater than 96%.

[0031] Example 2

[0032] This experiment used brine from a salt lake. The lithium extraction adsorbent was an aluminum-based adsorbent, and the potassium extraction material was ammonia-type natural clinoptilolite, a hydrotalcite-like material. The concentrations of the main ions in the brine were 0.65 g / L, 24 g / L, 5 g / L, 0.2 g / L, 3 g / L, and 0.4 g / L, respectively; the sulfate concentration was 12 g / L; and the brine pH was 5.5. Lithium extraction was performed on 5.5 BV brine using 50 mL (1 BV) of aluminum-based adsorbent. The lithium concentration in the tail brine was reduced to 0.05 g / L. The aluminum-based adsorbent was then regenerated using a 100 g / L sodium chloride solution (20 BV). After analysis with 160 mL of industrial reverse osmosis water, a lithium-rich solution with a lithium ion concentration of 950 mg / L was obtained. The lithium adsorption capacity was 3.4 g / L, and the desorption capacity was 3 g / L. When the sulfate concentration in the regenerated solution reached 10 g / L, further... The sodium sulfate precipitated from the raw liquid was prepared into a sodium sulfate solution with a sodium ion concentration of 90 g / L as a potassium extraction eluent. Then, 300 ml (6 BV) of ammonia-type natural clinoptilolite was used to conduct a potassium extraction adsorption test on 14 BV tail brine. The potassium in the tail brine was reduced to 1.5 g / L, and the potassium adsorption capacity was 8 g / L. The potassium extraction material was then eluented at 90℃ using a potassium extraction eluent prepared with 40 BV. The eluent capacity was 7.5 g / L, resulting in a qualified potassium-rich solution with a potassium ion concentration of 1.2 g / L. The lithium-rich qualified solution is treated by reverse osmosis, nanofiltration, and chelating resin to obtain a lithium-rich mother liquor with a lithium concentration of 12 g / L. Crude lithium hydroxide is prepared by bipolar membrane, and the final purity of lithium hydroxide reaches 99.2% by recrystallization. The potassium-rich qualified solution is evaporated to precipitate sodium sulfate, increasing the potassium sulfate ratio of the mother liquor. The mother liquor is then mixed with the next potassium-rich qualified solution for evaporation to precipitate sodium again, obtaining crude potassium sulfate. The final potassium sulfate product obtained by washing and drying has a purity greater than 92%.

[0033] Example 3

[0034] This experiment used brine from a salt lake. The lithium extraction adsorbent used was an aluminum-based adsorbent, and the potassium extraction material was sodium-type natural clinoptilolite. The concentrations of the main ions in the brine were 0.4 g / L, 100 g / L, 10 g / L, 0.15 g / L, 15 g / L, and 0.7 g / L, respectively; the sulfate concentration was 40 g / L; and the brine pH was 6. Lithium extraction was performed on 9BV brine using 50ml (1BV) of aluminum-based adsorbent. The lithium concentration in the tail brine decreased to 0.04g / L. The aluminum-based adsorbent was then regenerated using a 20BV sodium chloride solution with a concentration of 110g / L. After analysis with 160ml of pure water, a qualified lithium-rich solution with a lithium ion concentration of 800mg / L was obtained, with a lithium adsorption capacity of 3.1g / L and a desorption capacity of 2.6g / L. When the sulfate concentration in the regenerated solution was enriched to 10g / L, the sodium sulfate obtained by nanofiltration of the regenerated solution was used to prepare a potassium extraction desorption agent. Potassium extraction was then performed on 10BV tail brine using 300ml (6BV) of sodium-type natural clinoptilolite. The potassium concentration in the tail brine decreased to 2g / L, with a potassium adsorption capacity of 13g / L. The potassium extraction desorption agent prepared with 50BV was then used to desorb the potassium extraction material at 90℃, with a desorption capacity of 12.5g / L, resulting in a qualified potassium-rich solution with a potassium ion concentration of 1.5g / L. The lithium-rich qualified solution is treated by reverse osmosis, nanofiltration, chelating resin, etc. to obtain a lithium-rich mother liquor with a lithium concentration of 12g / L. After evaporation to precipitate sodium, cooling to precipitate potassium, and salt washing, the final lithium chloride is obtained with a purity of 98.5%. The potassium-rich qualified solution is evaporated to precipitate sodium sulfate, increasing the potassium sulfate ratio in the mother liquor. The mother liquor is then mixed with the next potassium-rich qualified solution for evaporation to precipitate sodium again, obtaining crude potassium sulfate. After salt washing and drying, the final potassium sulfate product has a purity greater than 95%.

[0035] Comparative Example 1

[0036] The difference from Example 1 is that no regeneration process is performed, and the potassium extraction agent is prepared using sodium sulfate reagent.

[0037] Comparative Example 2

[0038] The difference from Example 2 is that no regeneration process is performed, and the potassium extraction agent is prepared using sodium sulfate reagent.

[0039] Comparative Example 3

[0040] The difference from Example 3 is that no regeneration process is performed, and the potassium extraction agent is prepared using sodium sulfate reagent.

[0041]

[0042] Examples 1-3 used sodium sulfate obtained after treatment of the regenerated liquid. As can be seen from the table above, after 9 cycles of the cyclic experiment, the adsorption capacity of Examples 1-3 remained at 3.1 g / L, 3.4 g / L, and 3.15 g / L, respectively, without a significant downward trend. In contrast, the adsorption capacity of Comparative Examples 1-3 decreased to 1.55 g / L, 1.33 g / L, and 0.85 g / L, respectively, showing a continuous decline. This indicates that the adsorbent was poisoned, demonstrating that the regeneration process during the adsorption and desorption process successfully prevented the poisoning of the lithium extraction adsorbent and maintained its adsorption performance.

[0043] The corresponding sodium sulfate product from the regenerated liquid is used in the potassium extraction and desorption process, which also saves on the amount of sodium sulfate used, reducing the cost of the potassium extraction process alone and the cost of regenerated liquid treatment in the lithium extraction process alone.

Claims

1. A method for co-production of lithium and potassium from salt lake brine, characterized in that, The method comprises the following steps: The lithium extraction is completed by mixing the salt lake brine with the lithium extraction adsorbent, and tail brine after adsorption is obtained; The sulfate on the lithium extraction adsorbent is eluted by the regeneration liquid; The lithium on the lithium extraction adsorbent is eluted by the elution agent to obtain a qualified lithium-rich solution, and the lithium salt is obtained after concentration and impurity removal; The sulfate is washed out from the lithium extraction adsorbent by the regeneration liquid, the sulfate content in the regeneration liquid is gradually increased by recycling the regeneration liquid, and sodium sulfate is precipitated by freezing crystallization; The tail brine after adsorption is mixed with the potassium extraction material to extract potassium ions; The sodium sulfate precipitated by freezing crystallization is used to elute the potassium extraction material to obtain a potassium-rich solution, and the potassium sulfate is obtained by evaporation, washing and drying.

2. The method for co-producing lithium and potassium from salt lake brine according to claim 1, characterized in that, The sulfate content in the salt lake brine is greater than 10 g / L, and the ratio of chloride ions to sulfate is less than 5.

3. The method for co-producing lithium and potassium from salt lake brine according to claim 1, characterized in that, The regeneration liquid is a sodium chloride solution with a sodium ion concentration of more than 80 g / L.

4. The method for co-producing lithium and potassium from salt lake brine according to claim 1, characterized in that, The elution agent is one or a mixture of more than one of pure water, tap water, industrial reverse osmosis water and lithium-rich solution.

5. The method for co-producing lithium and potassium from salt lake brine according to claim 1, characterized in that, The concentration and impurity removal are performed by a membrane method, and the membrane method is one or a mixture of more than one of nanofiltration, reverse osmosis and electrodialysis.

6. The method for co-producing lithium and potassium from salt lake brine according to claim 1, characterized in that, The aluminum-based lithium extraction adsorbent is a combination of lithium chloride and aluminum chloride, LiAl-LDHS.

7. The method for co-producing lithium and potassium from salt lake brine according to claim 1, characterized in that, The potassium extraction material is one of modified natural clinoptilolite, hydrotalcite material and potassium ferrocyanide synthetic material.

8. The method for co-producing lithium and potassium from salt lake brine according to claim 1, characterized in that, The lithium salt is lithium carbonate.

9. The method for co-producing lithium and potassium from salt lake brine according to claim 1, characterized in that, The elution temperature is 85-95 DEG C.

10. The method for co-producing lithium and potassium from salt lake brine according to claim 1, characterized in that, The lithium ion concentration of the qualified lithium-rich solution is 700 mg / L or more, and the potassium ion concentration of the potassium-rich solution is 500 mg / L or more. The lithium extraction adsorbent is an aluminum-based lithium extraction adsorbent.

Images