Method for enriching lithium from medium- and low-concentration lithium-containing solution without evaporation

Abstract

The present invention relates to the technical field of resource recovery and reuse, and in particular to a method for enriching lithium from a medium- and low-concentration lithium-containing solution without evaporation, comprising the following steps: adding a support and a support activator to a medium- and low-concentration lithium-containing solution, once the stirring and reacting are completed, carrying out solid-liquid separation to obtain a lithium-enriched support and a lithium-depleted solution; fully washing the lithium-enriched support with hot water and then filtering, adding water and a desorption and regeneration agent to a filter cake, once the stirring and reacting are completed, carrying out solid-liquid separation to obtain a lithium-enriched solution having a lithium concentration greater than 10 g / L and a regenerated support. The present invention uses a chemical method to replace conventional evaporation processes for lithium concentration, greatly reduces energy consumption and save costs. The present invention involves a simple process and simple operation. No organic substances are introduced during lithium separation, and thus compared with an extraction process, the present invention will not cause organic contamination. The support in the present invention may be iron phosphate waste residues generated in the process of recovering lithium from lithium iron phosphate, thereby achieving better resource recovery and reuse.

Description

Method for enriching lithium from low-concentration lithium-containing solution without evaporation TECHNICAL FIELD

[0001] The present application belongs to the technical field of resource recycling and reuse, and particularly relates to the field of recycling and reuse of low-concentration lithium-containing solution for lithium extraction and enrichment and the field of recycling and reuse of metal materials. BACKGROUND

[0002] The present application belongs to the technical field of resource recycling and reuse, and particularly relates to the field of recycling and reuse of low-concentration lithium-containing solution for lithium extraction and enrichment and the field of recycling and reuse of metal materials.

[0003] BACKGROUND

[0004] In the production process of lithium carbonate, a solution with low lithium concentration (2-3 g / L) is generated. One source is the solution after lithium precipitation, that is, the solution generated after lithium is precipitated in the form of lithium carbonate by adding sodium carbonate to a lithium-containing mother liquor (lithium content ≥10 g / L); the other source is that the solid raw material itself contains less lithium, resulting in low lithium content in the obtained leaching solution. Depending on the properties of the raw material, the composition of the solution may also differ. Generally, the solution is concentrated to a concentration of ≥10 g / L. How to recycle and reuse the solution with low lithium concentration remains to be solved.

[0005] At present, the solution with low lithium concentration is often concentrated by evaporation. Obviously, this not only consumes a lot of energy, but also the impurities in the solution are concentrated together with lithium, resulting in low purity of the product obtained by subsequent lithium precipitation. Subsequently, an extraction method was developed, in which N523 and TBP are used as extractants to separate lithium from the solution, which plays a good purification role. However, the extractants are organic substances, and flammable substances such as sulfonated kerosene are often used as diluents in the production process, which has high safety requirements. In addition, the organic substances will partially dissolve in the solution system to form organic wastewater, which will increase the difficulty of wastewater treatment. Therefore, the current research direction is more active in inorganic adsorbents. The reported inorganic adsorbents include aluminum-based adsorbents, manganese-based adsorbents, titanium-based adsorbents, etc. Among them, the aluminum-based adsorbents are widely used in large-scale industrial applications, and other adsorbents have not been popularized due to difficulties in preparation, high price, and high dissolution loss rate. However, the aluminum-based adsorbents have a fatal defect, that is, they only have separation function for lithium and have very limited enrichment capacity, and they can only concentrate several hundred milligrams of lithium to 1-2 g / L. In order to achieve further concentration, evaporation is still required. How to economically and efficiently enrich the low-concentration lithium-containing solution is still a big problem in the industry.

[0006] CN118308605A discloses a method and application for enriching lithium, including the following steps: step 1, obtaining a multi-metal solution containing lithium ions; step 2, uniformly mixing the initial extractant with the alkali solution and performing saponification process to obtain the first extractant; step 3, adding the multi-metal solution containing lithium ions into the first extractant to perform lithium transfer saponification process; step 4, recovering lithium ions in the solution after lithium transfer saponification process. Thus, by adding lithium transfer saponification process after saponification process, the metal ions carried by the alkali solution are removed, thereby extracting lithium and improving the recovery rate of lithium. This method realizes enrichment of lithium, but still adds organic extractant, which has the problems of organic pollution and difficult treatment of organic wastewater as described above.

[0007] CN117778751A discloses a system and method for extracting and enriching lithium from a lithium-containing solution. When extracting lithium, the lithium extraction active substance and the electron transfer substance are placed in the lithium-containing solution, and hydrogen gas is introduced into the lithium-containing solution to cause the following reactions: hydrogen gas transfers electrons to the electron transfer substance; the electron transfer substance transfers the received electrons to the lithium extraction active substance; the lithium extraction active substance adsorbs lithium ions in the lithium-containing solution; when de-lithiating, the pre-de-lithiation active substance and the electron transfer substance are placed in the lithium extraction solution, and oxygen gas is introduced into the lithium extraction solution to cause the following reactions: oxygen gas obtains the electrons of the electron transfer substance, the electron active substance obtains the electrons on the pre-de-lithiation active substance, and the pre-de-lithiation active substance releases lithium ions into the lithium extraction solution. The selective lithium extraction and de-lithiation are achieved through a catalytic reaction involving gas, without external potential. The lithium extraction and de-lithiation process driven by the catalytic reaction has low energy consumption, and the gas involved in the lithium extraction and de-lithiation avoids complex chemical substance separation. Although this method realizes enrichment of lithium, it is relatively complex.

[0008] In addition, with the vigorous development of the lithium recovery industry, the retirement rate of waste lithium iron phosphate batteries is gradually increasing, and the amount of waste lithium iron phosphate slag will continue to increase. How to recycle waste lithium iron phosphate slag needs to be studied. Waste lithium iron phosphate slag is usually black, gray or brown, hard in texture, and has strong adhesion, containing a large amount of iron ions and a large amount of phosphate ions, and has high chemical activity. There are many existing technologies for treating waste lithium iron phosphate slag, such as CN118387848A discloses a method for recycling and preparing battery-grade lithium iron phosphate from waste lithium iron phosphate slag, CN116986567B discloses a method for recycling lithium iron phosphate from waste lithium iron phosphate slag, and CN113184821B discloses a method for preparing lithium iron phosphate from iron-containing slag. How to more simply utilize waste lithium iron phosphate slag needs to be studied.

[0009] Therefore, it is of great significance to develop a method for enriching lithium without adding organic matter and evaporation, and to recycle waste lithium iron phosphate slag. SUMMARY

[0010] In view of the deficiencies of the prior art, the purpose of the present application is to provide a method for enriching lithium from a low-concentration lithium-containing solution without evaporation. The process of the present application is simple, does not add organic matter, does not use evaporation concentration techniques, avoids organic pollution, saves energy consumption, and the carrier used in the method of the present application can be iron phosphate waste residue, which is recycled. The method of the present application is mainly aimed at a lithium-containing solution with a lithium ion concentration of less than 10 g / L, and further mainly aimed at a lithium-containing solution with a lithium ion concentration of 1-3 g / L.

[0011] To achieve the purpose of the present application, the technical solution of the present application is:

[0012] A method for enriching lithium from a low-concentration lithium-containing solution without evaporation, comprising the following steps:

[0013] (1) A carrier and a carrier activator are first added to the low-concentration lithium-containing solution, the reaction temperature is controlled at 0-100ºC, and the reaction is carried out for 5 min-24 h. After the reaction is completed, solid-liquid separation is carried out to obtain a lithium-rich carrier and a lithium-extracted solution. The carrier is an insoluble phosphate and / or iron phosphate waste residue, and the carrier activator is an alkaline substance. The lithium ion concentration in the low-concentration lithium-containing solution is less than 10 g / L.

[0014] (2) The obtained lithium-rich carrier is washed to remove impurities and then filtered. Water is added to the obtained filter cake, and a carrier elution regenerating agent is then added. The carrier elution regenerating agent is an acidic substance, the reaction temperature is controlled at 0-100ºC, and the reaction is carried out for 5 min-24 h. After the reaction is completed, solid-liquid separation is carried out to obtain a lithium-rich solution and a regenerated carrier.

[0015] Preferably, the carrier in step (1) comprises one or more of iron phosphate waste residue, iron phosphate, aluminum phosphate, calcium phosphate, magnesium phosphate, and their acid or alkali salts.

[0016] Preferably, the iron phosphate waste residue is the iron phosphate waste residue generated in the process of recovering lithium from lithium iron phosphate.

[0017] Preferably, the carrier activator in step (1) comprises one or more of sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide.

[0018] Preferably, the low-concentration lithium-containing solution in step (1) refers to a solution with a lithium concentration ranging from 1 to 6 g / L.

[0019] Preferably, the low-concentration lithium-containing solution in step (1) refers to a lithium-containing solution with a lithium concentration ranging from 1 to 3 g / L.

[0020] Preferably, the carrier in step (1) is added in a ratio of 5-200 g carrier per 1 L of the low-concentration lithium-containing solution. Further preferably, the ratio is 10-100 g carrier per 1 L of the low-concentration lithium-containing solution. Further preferably, the ratio is 10-50 g carrier per 1 L of the low-concentration lithium-containing solution.

[0021] Preferably, the carrier activator in step (1) is added in a ratio of 5-400 g basic substance per 1 L of the low-concentration lithium-containing solution. Further preferably, the ratio is 10-200 g carrier per 1 L of the low-concentration lithium-containing solution. Further preferably, the ratio is 10-40 g basic substance per 1 L of the low-concentration lithium-containing solution.

[0022] Preferably, the reaction temperature in step (1) is controlled at 60-100ºC for 1-5 h.

[0023] Preferably, the reaction temperature in step (2) is controlled at 60-100ºC for 1-5 h.

[0024] Preferably, the carrier elution regenerant in step (2) comprises one or more of sulfuric acid, nitric acid, and hydrochloric acid.

[0025] Preferably, the impurity removal by washing in step (2) comprises multiple washings with hot water at a temperature of 40ºC-100ºC. The amount of water used for washing is not specifically required and can be adjusted according to actual conditions.

[0026] Preferably, the water in step (2) is added in a ratio of 1:1-5 (m filter cake:m water).

[0027] Preferably, the carrier elution regenerant in step (2) is added in a ratio of 1:0.1-2 (m filter cake:m carrier elution regenerant).

[0028] Preferably, the lithium ion concentration in the lithium-rich solution in step (2) is 10-30 g / L.

[0029] The present application stimulates the reactivity of the carrier (e.g., insoluble phosphate) by adding a carrier activator (e.g., a basic substance) to capture lithium in the solution, and then elutes and regenerates (e.g., acid dissolves) the captured solid phase to make lithium enter the liquid phase, thereby obtaining enrichment. The process of acid dissolving lithium is also a regeneration process of the carrier, and thus the carrier can be reused.

[0030] Compared with the prior art, the present application has the following advantages:

[0031] 1. The method of the present application is simple and easy to operate, and uses chemical method to replace the traditional evaporation process for concentrating lithium, which is different from the traditional high-energy-consumption evaporation concentration method, greatly saving energy consumption.

[0032] 2、The carrier used in the present application is cheap and reusable, and no organic substance is introduced in the process of separating lithium, so no organic pollution is caused compared with the traditional extraction process.

[0033] 3、In the enrichment process of the method of the present application, lithium is separated from other alkali metals such as sodium and potassium, and a high-purity high-lithium solution can be directly obtained.

[0034] 4、The carrier used in the present application is insoluble phosphate, especially iron phosphate, which is easy to obtain; in the process of recovering lithium from lithium iron phosphate, iron phosphate waste residue is produced as waste, and the iron phosphate waste residue has high purity and contains a large amount of iron ions and phosphate radicals, which can be directly used and regenerated as the carrier in the present application. Embodiment of the present application

[0035] The detailed structure of the present application is further described below in combination with specific embodiments. The insoluble phosphate used in the embodiments 1-3 of the present application is a commercially available product.

[0036] Embodiment 1

[0037] A method for enriching lithium from a low-concentration lithium-containing solution without evaporation, 1L of a solution containing 2.13g / L of lithium is taken, 20g of iron phosphate is added, and after stirring uniformly, 16g of sodium hydroxide is added, the temperature is controlled at 80ºC, and the reaction is carried out for 2h, then filtration is performed, 40.94g of filter cake (with a water content of 48.7%) is obtained, the lithium content of the solution after lithium extraction is measured to be 226mg / L, and it is calculated that the apparent loading capacity of lithium in the carrier is 95.2mg / g based on 20g of dry basis; the filter cake is washed with hot water at 95ºC for three times, then 100mL of water is added to the filter cake, stirring is performed to disperse and uniform, then 8mL of concentrated sulfuric acid (concentration 98%) is added, the reaction is continued for 3h, the reaction temperature is controlled at 95ºC, and after completion, filtration is performed, 14.69g / L of lithium-rich solution and regenerated iron phosphate are obtained.

[0038] Table 1 Comparison of components of low-concentration lithium-containing solution and lithium-rich solution

[0039] Solution lithium ion concentration sodium ion concentration potassium ion concentration Raw material 2.13g / L 20.54g / L 2.77g / L Enriched 14.69g / L 0.234g / L 0.032g / L

[0040] The regenerated iron phosphate of embodiment 1 can be repeatedly used as the carrier for the next enrichment of lithium and reused, and after being reused for 8 times by the method of embodiment 1, the apparent loading capacity of lithium in the carrier is still >90mg / g.

[0041] Embodiment 2

[0042] A method for enriching lithium from a low-concentration lithium-containing solution without evaporation, 1 L of a solution containing 2.21 g / L of lithium is taken, 20 g of aluminum phosphate is added, after stirring uniformly, 14 g of sodium hydroxide is added, the temperature is controlled at 60ºC, and the reaction is carried out for 2 h, then filtration is performed, 42.58 g of filter cake is obtained (with a water content of 54.83%), the lithium content of the solution after lithium extraction is 794.9 mg / L, and according to the calculation, the apparent loading capacity of lithium in the carrier is 70.76 mg / g based on 20 g of dry basis; the filter cake is washed with hot water at 80ºC for three times, then 50 mL of water is added to the filter cake, after stirring and uniformly dispersing, 6 mL of concentrated sulfuric acid (concentration 98%) is added, the reaction is continued for 2 h, the reaction temperature is controlled at 95ºC, after completion, filtration is performed, and 17.38 g / L of a lithium-rich solution and regenerated aluminum phosphate are obtained.

[0043] Table 2 Comparison of components of a low-concentration lithium-containing solution and a lithium-rich solution

[0044] Solution lithium ion concentration sodium ion concentration potassium ion concentration raw material 2.21 g / L 11.2 g / L 3.88 g / L after enrichment 17.38 g / L 0.325 g / L 0.07 g / L

[0045] Example 2 The regenerated aluminum phosphate can be repeatedly used as a carrier for the next enrichment of lithium. After being reused for 8 times by the method of Example 1, the apparent loading capacity of lithium in the carrier is still >70 mg / g.

[0046] Example 3

[0047] A method for enriching lithium from a low-concentration lithium-containing solution without evaporation, 1 L of the lithium-containing solution of Example 2 is taken, 10 g of the regenerated iron phosphate of Example 1 is added, then 10 g of the regenerated aluminum phosphate of Example 2 is added, after stirring uniformly, 12 g of sodium hydroxide is added, the temperature is controlled at 90ºC, and the reaction is carried out for 2 h, then filtration is performed, 41.24 g of filter cake is obtained (with a water content of 50.44%), the lithium content of the solution after lithium extraction is 523.3 mg / L, and according to the calculation, the apparent loading capacity of lithium in the carrier is 84.33 mg / g based on 20 g of dry basis; the filter cake is washed with hot water at 95ºC for three times, then 60 mL of water is added to the filter cake, after stirring and uniformly dispersing, 20 mL of hydrochloric acid (concentration 36%) is added, the reaction is continued for 2 h, the reaction temperature is controlled at 95ºC, after completion, filtration is performed, and 16.45 g / L of a lithium-rich solution and a regenerated carrier (including iron phosphate and aluminum phosphate) are obtained.

[0048] Table 3 Comparison of components of a low-concentration lithium-containing solution and a lithium-rich solution

[0049] Solution lithium ion concentration sodium ion concentration potassium ion concentration raw material 2.21 g / L 11.2 g / L 3.88 g / L after enrichment 16.45 g / L 0.284 g / L 0.054 g / L

[0050] Example 4

[0051] Iron phosphate waste residue is used as the carrier of the present application. The iron phosphate waste residue is the iron phosphate waste residue produced in the process of recovering lithium from lithium iron phosphate.

[0052] Table 4: Content detection results of iron and phosphorus elements in iron phosphate waste residue

[0053] Iron element Wt% Phosphorus element Wt% Mass percentage content 32.456% 18.575%

[0054] Specific steps: take 1L of lithium-containing solution of Example 2, add 18g of the above-mentioned iron phosphate waste residue, stir uniformly, then add 16g of sodium hydroxide, control the temperature at 90ºC, react for 3h, then filter to obtain 37.13g of filter cake (water content 48.88%), measure the lithium content of the lithium-extracted solution to be 276.2mg / L, and calculate that the apparent loading capacity of lithium in the carrier is 107.43mg / g based on 18g of dry basis; wash the filter cake with hot water at 98ºC for three times, then add 51mL of water to the filter cake, stir and disperse uniformly, then add 9mL of concentrated sulfuric acid (concentration 98%), continue to react for 3h, control the reaction temperature at 95ºC, and after completion, filter to obtain 24.74g / L of lithium-rich solution and regenerated carrier.

[0055] Table 5: Comparison of components of lithium-containing low-concentration solution and lithium-rich solution

[0056] Solution lithium ion concentration sodium ion concentration potassium ion concentration raw material 2.21g / L 11.2 g / L 3.88 g / L after enrichment 24.74g / L 0.313 g / L 0.032g / L

[0057] In addition to the iron phosphate waste residue produced in the process of recovering lithium from lithium iron phosphate, other iron phosphate waste residues can also be used, mainly to have a high content of iron ions and phosphate ions. The technology for recovering iron phosphate from iron phosphate waste residue is prior art, and any method in the prior art can be used for recovery, for example, the iron phosphate recovered by the method of the patent described in the background can be used as the carrier of the present application. Some iron phosphate waste residues have low impurity content and can be directly used. Comparative Example 1

[0058] The specific steps are the same as those of Example 1, except that the iron phosphate (insoluble phosphate) is replaced by sodium phosphate (soluble phosphate). After adding water and acid, all the lithium phosphate precipitates are dissolved, although the lithium ions are enriched, but the phosphorus is not separated, and the potassium phosphate cannot be reused, i.e. the soluble phosphate cannot play the role of carrier in the present application. Comparative Example 2

[0059] The specific steps are the same as those in Example 1, except that no alkali sodium hydroxide is added, the carrier is not activated, the loading reaction cannot be achieved, and lithium ions cannot be enriched.

[0060] The above are specific embodiments of the present application, but the scope of protection of the present application is not limited thereto, and any skilled person in the art can make equivalent replacements or changes within the technical scope disclosed by the present application according to the technical solutions and concepts of the present application, which should be covered within the scope of protection of the claims of the present application.

[0061] The above are specific embodiments of the present application, but the scope of protection of the present application is not limited thereto, and any skilled person in the art can make equivalent replacements or changes within the technical scope disclosed by the present application according to the technical solutions and concepts of the present application, which should be covered within the scope of protection of the claims of the present application.

Claims

1. A method of evaporation-free lithium enrichment from a low to medium concentration solution containing lithium, characterized in that: The method comprises the following steps: (1) adding a carrier and a carrier activator to a lithium-containing low-concentration solution, controlling the reaction temperature to be 0-100ºC, and reacting for 5 min-24 h, then performing solid-liquid separation after the reaction is completed to obtain a lithium-rich carrier and a solution after lithium extraction; the carrier is insoluble phosphate and / or iron phosphate waste residue, and the carrier activator is an alkaline substance; the lithium ion concentration in the lithium-containing low-concentration solution is less than 10 g / L; (2) filtering the lithium-rich carrier obtained after washing and impurity removal, adding water to the filter cake obtained, and then adding a carrier desorption regenerant, the carrier desorption regenerant being an acidic substance, controlling the reaction temperature to be 0-100ºC, and reacting for 5 min-24 h, then performing solid-liquid separation after the reaction is completed to obtain a lithium-rich solution and a regenerated carrier.

2. The method for enriching lithium from a lithium-containing low-concentration solution without evaporation according to claim 1, wherein the carrier in step (1) comprises one or more of iron phosphate waste residue, iron phosphate, aluminum phosphate, calcium phosphate, magnesium phosphate, and acid or alkali salts thereof.

3. The method for enriching lithium from a lithium-containing low-concentration solution without evaporation according to claim 2, wherein the iron phosphate waste residue is iron phosphate lithium recovery lithium process-generated iron phosphate waste residue.

4. The method for enriching lithium from a lithium-containing low-concentration solution without evaporation according to claim 1, wherein the carrier activator in step (1) comprises one or more of sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide.

5. The method for enriching lithium from a lithium-containing low-concentration solution without evaporation according to any one of claims 1-4, wherein the lithium-containing low-concentration solution refers to a solution with a lithium concentration ranging from 1 g / L to 6 g / L.

6. The method for enriching lithium from a lithium-containing low-concentration solution without evaporation according to claim 5, wherein the lithium-containing low-concentration solution refers to a lithium-containing solution with a lithium concentration ranging from 1 g / L to 3 g / L.

7. The method for enriching lithium from a lithium-containing low-concentration solution without evaporation according to any one of claims 1-4, wherein the carrier in step (1) is added in a proportion of 5-200 g of carrier per 1 L of lithium-containing low-concentration solution.

8. The method for enriching lithium from a lithium-containing low-concentration solution without evaporation according to any one of claims 1-4, wherein the carrier activator in step (1) is added in a proportion of 5-400 g of alkaline substance per 1 L of lithium-containing low-concentration solution.

9. The method for enriching lithium from a lithium-containing low-concentration solution without evaporation according to any one of claims 1-4, wherein the carrier desorption regenerant in step (2) comprises one or more of sulfuric acid, nitric acid, and hydrochloric acid.

10. The method for enriching lithium from a lithium-containing low-concentration solution without evaporation according to any one of claims 1-4, wherein the washing and impurity removal in step (2) comprises multiple times of washing with hot water with a temperature of 40ºC-100ºC.

11. The method for enriching lithium from a lithium-containing low-concentration solution without evaporation according to any one of claims 1-4, wherein the water in step (2) is added in a proportion of filter cake mass: water mass = 1:1-5.

12. The method for enriching lithium from lithium-containing low-to-medium concentration solution without evaporation according to any one of claims 1-4, wherein the carrier desorption regenerant is added in a ratio of filter cake mass to carrier desorption regenerant mass of 1:0.1-2 in step (2).

13. The method for enriching lithium from lithium-containing low-to-medium concentration solution without evaporation according to any one of claims 1-4, wherein the lithium ion concentration in the lithium-enriched solution is 10-30 g / L in step (2).