A method for the comprehensive recovery of lithium, rubidium, and cesium from lithium ore leaching solution

Abstract

This invention discloses a method for the comprehensive recovery of lithium, rubidium, and cesium from lithium ore leachate. It employs a combined process of cascade extraction-washing-back-extraction and electrodialysis, which not only efficiently separates valuable metals such as lithium, rubidium, and cesium from alkaline earth metals such as sodium, potassium, and calcium in the lithium ore leachate, but also significantly reduces the amount of water entering the rubidium and cesium extraction stages compared to a single extraction system by initially concentrating the lithium extraction residue. This invention uses cascade extraction-washing-back-extraction after sodium carbonate precipitation to remove calcium from the leachate, thus enriching lithium and avoiding the drawback of low lithium recovery rates caused by lithium entrainment in crystallized salts during traditional evaporation and concentration processes. This invention also employs stepwise extraction of rubidium and cesium, using cascade washing to remove most impurity ions before back-extraction enrichment to obtain high-purity cesium-rich and rubidium-rich solutions, thereby preparing high-purity rubidium and cesium salt products. The method of this invention is simple to operate, has no environmental hazards, and is applicable to the recovery of valuable metals such as lithium, rubidium, and cesium from most lithium ores.

Description

Technical Field

[0001] This invention relates to the fields of non-ferrous metal smelting and environmental protection, specifically to a method for the comprehensive recovery of lithium, rubidium, and cesium from lithium ore leachate. Background Technology

[0002] Lithium, as the lightest and least dense metal, possesses unique physicochemical properties. In recent years, with the rapid development of electrochemical energy storage and electric vehicles, its application in new energy materials has become increasingly apparent, and its development and utilization have received significant attention. Rubidium and cesium often coexist with their chemically similar group members such as lithium, sodium, and potassium, existing mainly in combined forms in nature at relatively low concentrations. Rubidium and cesium have essentially similar physicochemical properties, both exhibiting extremely reactive chemical properties and excellent photoelectric characteristics, leading to their widespread application in electronics, chemical engineering, energy, and medicine, such as in aerospace and defense ion rocket propulsion, optoelectronic materials, and specialty glasses.

[0003] However, due to the current surge in lithium demand, most processes primarily focus on lithium extraction from salt lake brines or lithium ores, with limited research on rubidium and cesium recovery. After lithium extraction, the resulting solution, after recovering other economically valuable metals, is generally treated as solid waste, resulting in a significant waste of these rare metals. Lithium, rubidium, and cesium resources are mainly found in ores and salt lake brines. Processes for the comprehensive extraction of valuable metals from lithium ores primarily include limestone sintering, sulfate extraction, chlorination roasting, and compound salt roasting combined with chemical leaching to transfer lithium, rubidium, and cesium from the minerals into a solution for further processing into lithium salts, rubidium salts, and cesium salts. Lithium extraction from lithium ore leachates is a relatively mature process; industrially, chemical precipitation is commonly used, where the leachate is concentrated by evaporation and then sodium carbonate is added to precipitate lithium and prepare lithium carbonate. Existing rubidium and cesium extraction processes mainly include precipitation, ion exchange, and solvent extraction. Precipitation is a method for extracting rubidium and cesium by stepwise crystallization and precipitation of the lithium-extracting liquid. This method is complex, has a low recovery rate, and may introduce trace impurities, increasing the difficulty of impurity removal. Ion exchange methods utilize organic ion exchangers, whose effectiveness is limited by factors such as temperature when high-valence ions coexist, while inorganic ion exchangers have high solubility in water. Solvent extraction, compared to ion exchange, is simpler, requires less equipment, has higher extraction efficiency, and is suitable for mass production; it is currently the most commonly used method for rubidium and cesium extraction.

[0004] Patent CN113174480A discloses a method for extracting lithium, rubidium, and cesium from lithium-, rubidium-, and cesium-containing silicate minerals. This method involves mixing finely ground mineral powder with calcium chloride and a chlorination agent in a specific ratio and then roasting at high temperature. The roasted calcined ore is then chemically leached to transfer the lithium, rubidium, and cesium metals into a solution. The leachate is then chemically precipitated to obtain lithium salts, and the precipitated lithium solution is then extracted and back-extracted to obtain rubidium and cesium salts. This patent increases the utilization rate of calcium chloride by adding a chlorine-fixing agent, and the roasting process produces no chlorine tail gas, solving the problem of chlorine content in the flue gas of traditional chlorination roasting. However, this technical solution only involves the principle process flow for recovering lithium, rubidium, and cesium from silicate mineral powder. It does not mention issues such as impurity removal from the leaching solution, co-extraction and removal of impurities in the extraction-back-extraction stage, and the disposal of the extraction residue, resulting in insufficient process integrity. This will inevitably lead to low metal recovery rate and low purity of lithium, rubidium, and cesium products. At the same time, this technical solution uses chlorination roasting, and the leaching and extraction are also equivalent to the chloride system, making wastewater treatment more complicated than the sulfuric acid system.

[0005] Patent CN107475537A discloses a method for extracting lithium, rubidium, and cesium from lepidolite raw materials. Using lepidolite as raw material, the method involves mechanical activation treatment, roasting, pressure boiling and acid leaching, addition of alum crystallizing agent, impurity removal and neutralization, and concentration, separation, and extraction to obtain lithium salts, rubidium salts, and cesium salts respectively. This patent combines controlled low-temperature roasting with plasma high-temperature roasting for defluorination and mechanical activation treatment of the roasted sand, enabling the maximum separation and extraction of metal elements from lepidolite ore and deep removal of residual fluorine, significantly improving the utilization rate of lithium, rubidium, and cesium in lepidolite ore. Although this technical solution uses a stepwise extraction method to recover rubidium and cesium from the lithium precipitation mother liquor and reduce the entrainment loss of rubidium during the cesium extraction process, it does not consider the problem of sodium and potassium co-extraction affecting the purity of cesium and rubidium salt products. At the same time, this technical solution uses seed crystal precipitation to recover lithium. Due to solubility limitations, the lithium precipitation mother liquor still contains a considerable amount of lithium (1.5-2 g / L), resulting in a low lithium separation and extraction rate.

[0006] Patent CN115180640A discloses a method for extracting rubidium and cesium salts from a lithium-extraction solution from lepidolite. This method employs a cryogenic purification process, introducing high-purity carbon dioxide gas during back-extraction to achieve rubidium and cesium extraction under weakly acidic conditions. The extraction and back-extraction are performed continuously in a streamlined manner, simultaneously separating and extracting rubidium and cesium. However, this technical solution does not perform stepwise extraction of cesium and rubidium. Although washing removes most of the sodium and potassium from the cesium- and rubidium-loaded organic phase, cesium and rubidium cannot be completely separated, resulting in a mixed cesium and rubidium salt product. Furthermore, this technical solution uses pure water and carbon dioxide for washing and back-extraction of the rubidium- and cesium-loaded organic phase. While this avoids the corrosive effects of strong acids on the equipment, some cesium and rubidium remain in the organic phase, leading to low recovery rates. Additionally, the utilization rate of the weakly acidic carbonic acid formed by carbon dioxide and water is low, requiring more back-extraction stages to achieve rubidium and cesium enrichment. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention aims to provide a method for the comprehensive recovery of lithium, rubidium, and cesium from lithium ore leaching solutions.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for the comprehensive recovery of lithium, rubidium, and cesium from lithium ore leaching solution includes the following steps:

[0010] S1. Add sodium carbonate to the lithium ore leachate after impurity removal to remove calcium;

[0011] S2. The calcium-removed liquid obtained in step S1 is mixed with the extractant and subjected to 1 to 10 stages of countercurrent extraction. After the extraction reaches equilibrium, the phases are separated to obtain the lithium extraction residue and the lithium-loaded organic phase. The lithium-loaded organic phase is transferred to step S2, and the lithium extraction residue is transferred to step S6.

[0012] S3. The lithium-loaded organic phase obtained in step S2 is mixed with the washing solution and then subjected to 1 to 10 stages of countercurrent or crosscurrent washing to obtain a sodium-potassium washing solution and a washed lithium-loaded organic phase. The sodium-potassium washing solution is returned to step S2 for lithium extraction.

[0013] S4. After mixing the washed lithium-loaded organic phase obtained in step S3 with the back-extraction solution, perform 1 to 10 stages of countercurrent or crosscurrent back-extraction. After the extraction equilibrium is reached, separate the phases to obtain lithium-rich back-extraction solution and empty organic phase. The empty organic phase is returned to step S2 as an extractant to participate in the extraction.

[0014] S5. Add sodium carbonate to the lithium-rich back-extraction solution obtained in step S4 to precipitate lithium and obtain lithium precipitation mother liquor and lithium carbonate product. The lithium precipitation mother liquor is returned to step S1 for decalcification of lithium ore leaching solution.

[0015] S6. The lithium extraction residue obtained in step S2 is concentrated by electrodialysis to obtain fresh water and concentrated water.

[0016] S7. After adjusting the pH of the concentrated water obtained in step S6, mix it with the extractant and perform 1 to 10 stages of countercurrent extraction. After the extraction reaches equilibrium, separate the phases to obtain the cesium-loaded organic phase and the cesium extraction residue. The cesium-loaded organic phase is transferred to step S8, and the cesium extraction residue is transferred to step S11.

[0017] S8. After mixing the cesium-loaded organic phase obtained in step S7 with the washing solution, perform 1 to 10 stages of countercurrent or crosscurrent washing to obtain a rubidium-containing washing solution and a washed cesium-loaded organic phase. The rubidium-containing washing solution is returned to step S7 to continue cesium extraction.

[0018] S9. The washed cesium-loaded organic phase obtained in step S8 is mixed with the back-extraction solution and subjected to 1 to 10 stages of countercurrent or crosscurrent back-extraction. After the extraction equilibrium is reached, the phases are separated to obtain a cesium-rich back-extraction solution and an empty organic phase. The empty organic phase is returned to step S7 as an extractant to participate in the extraction.

[0019] S10. Evaporate and crystallize the cesium-rich back-extraction solution obtained in step S9 to obtain the cesium salt product;

[0020] S11. Adjust the pH of the cesium extraction residue obtained in step S7 and then mix it with the extractant for 1 to 10 stages of countercurrent extraction. After extraction equilibrium, separate the phases to obtain rubidium extraction residue and rubidium-supported organic phase. Evaporate and crystallize the rubidium extraction residue to open the sodium and potassium salts.

[0021] S12. The rubidium-carrying organic phase obtained in step S11 is mixed with the washing liquid and then subjected to 1 to 10 stages of countercurrent or crosscurrent washing to obtain a sodium-potassium washing liquid and a washed rubidium-carrying organic phase. The sodium-potassium washing liquid is returned to step S11 for rubidium extraction.

[0022] S13. The washed rubidium-loaded organic phase obtained in step S12 is mixed with the back-extraction solution and subjected to 1 to 10 stages of countercurrent or crosscurrent back-extraction. After the extraction equilibrium is reached, the phases are separated to obtain a rubidium-rich back-extraction solution and an empty organic phase. The empty organic phase is returned to step S11 as an extractant to participate in the extraction.

[0023] S14. Evaporate and crystallize the rubidium-rich back-extraction solution obtained in step S13 to obtain the rubidium salt product.

[0024] Further, in step S2, the extractant and the decalcified liquid are mixed in a volume ratio of 1:10 to 10:1, and the single-stage extraction time is 1 to 30 minutes; the extractant is a combination of diketone compounds, organophosphorus compounds and kerosene.

[0025] Further, in step S3, the lithium-loaded organic phase and the washing solution are mixed in a volume ratio of 1:1 to 20:1, and the single-stage washing time is 1 to 30 minutes; the washing solution is one or more of hydrochloric acid, sulfuric acid or nitric acid solutions with an acid concentration of 0.05 to 0.5 mol / L.

[0026] Further, in step S4, the washing lithium-loaded organic phase and the back-extraction solution are mixed in a volume ratio of 1:1 to 50:1, and the single-stage back-extraction time is 1 to 30 minutes; the back-extraction solution is one or more of hydrochloric acid, sulfuric acid or nitric acid solutions with an acid concentration of 5 to 15 mol / L.

[0027] Further, in step S7, the concentrated water is adjusted to pH 9-13 by adding alkali; the extractant and the pH-adjusted concentrated water are mixed in a volume ratio of 1:10-10:1, and the single-stage extraction time is 1-30 min; the extractant is a mixture of 4-tert-butyl-2-(α-methylbenzyl)phenol and sulfonated kerosene, and the concentration of 4-tert-butyl-2-(α-methylbenzyl)phenol is 0.1-1 mol / L.

[0028] Further, in step S8, the cesium-carrying organic phase and the washing solution are mixed in a volume ratio of 1:1 to 20:1, and the single-stage washing time is 1 to 30 minutes; the washing solution is one or more of hydrochloric acid, sulfuric acid or nitric acid solutions with an acid concentration of 0.5 to 2 mol / L.

[0029] Further, in step S9, the washing cesium-carrying organic phase and the back-extraction solution are mixed in a volume ratio of 1:1 to 50:1, and the single-stage back-extraction time is 1 to 30 minutes; the back-extraction solution is one or more of hydrochloric acid, sulfuric acid or nitric acid solutions with an acid concentration of 0.1-1 mol / L.

[0030] Further, in step S11, the pH of the cesium extraction residue is adjusted to 11-14 by adding alkali; the extractant is a mixture of 4-tert-butyl-2-(α-methylbenzyl)phenol and sulfonated kerosene, and the concentration of 4-tert-butyl-2-(α-methylbenzyl)phenol is 1-5 mol / L; the extractant and the pH-adjusted cesium extraction residue are mixed at a volume ratio of 1:10 to 10:1, and the single-stage extraction time is 1-30 min.

[0031] Further, in step S12, the rubidium-carrying organic phase and the washing solution are mixed in a volume ratio of 1:1 to 20:1, and the single-stage washing time is 1 to 30 minutes; the washing solution is one or more of hydrochloric acid, sulfuric acid or nitric acid solutions with an acid concentration of 0.5 to 5 mol / L.

[0032] Further, in step S13, the washing rubidium-carrying organic phase and the back-extraction solution are mixed in a volume ratio of 1:1 to 50:1, and the single-stage back-extraction time is 1 to 30 minutes; the back-extraction solution is one or more of hydrochloric acid, sulfuric acid or nitric acid solutions with an acid concentration of 0.3-2 mol / L.

[0033] The beneficial effects of this invention are as follows:

[0034] 1) This invention employs a process combining cascade extraction-washing-back-extraction and electrodialysis, which not only efficiently separates valuable metals such as lithium, rubidium, and cesium from alkaline earth metals such as sodium, potassium, and calcium in lithium ore leachate, but also significantly reduces the amount of water entering the rubidium and cesium extraction stages compared to a single extraction system by initially concentrating the lithium extraction residue.

[0035] 2) Unlike the existing lithium extraction process from lithium ore, which uses leaching solution evaporation and concentration followed by sodium carbonate precipitation, this invention uses a cascade extraction-washing-back-extraction method to enrich lithium after calcium removal from the leaching solution via sodium carbonate precipitation. This avoids the drawback of low lithium recovery rate caused by lithium entrainment in the crystallized salt during the traditional evaporation and concentration process.

[0036] 3) This invention addresses the problem that traditional lithium extraction tailings co-extraction of rubidium and cesium leads to difficulty in separating the two, resulting in low purity of rubidium and cesium salt products. The process is optimized to extract rubidium and cesium in steps. To address the problem of other impurity ions being carried over in the cesium- and rubidium-supported organic phases, a cascade washing method is used to wash away most of the impurity ions before back-extraction and enrichment to obtain high-purity cesium-rich and rubidium-rich solutions, thereby preparing high-purity rubidium and cesium salt products.

[0037] 4) The lithium precipitation mother liquor obtained after preparing lithium carbonate from lithium-rich back-extraction solution is returned to the calcium removal stage of the leaching solution, which not only reduces the cost of reagents but also realizes the utilization of alkali and the recovery of residual lithium.

[0038] 5) The method of the present invention is simple to operate, has no environmental hazards, and is applicable to the recovery of valuable metals such as lithium, rubidium, and cesium from most lithium ores. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the method flow of various embodiments of the present invention. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0041] Example 1

[0042] The method and process for the comprehensive recovery of lithium, rubidium, and cesium from lithium ore leaching solution provided in this embodiment are as follows: Figure 1 As shown in Table 1, a leaching solution of roasted lepidolite ore was used as raw material, and its main components are shown in Table 1.

[0043] Table 1. Element content (g / L) of a certain lithium mica roasted sand leachate

[0044] element Li Rb Cs K Na Ca <![CDATA[SO4 2- ]]> pH content 2.21 1.64 0.12 18.4 10.8 0.64 63.64 8.5

[0045] Decalcification of leachate: Sodium carbonate with a lithium equivalent of 60% is added to the leachate for decalcification, with a decalcification rate of over 99.5%. The decalcified solution then enters the lithium extraction section.

[0046] Lithium extraction: The decalcified solution was subjected to a diketone-based extraction system combined with organophosphorus compounds and kerosene. The organic phase was mixed with the decalcified solution at a volume ratio of 1.5:1 and subjected to a three-stage countercurrent extraction. After phase separation and clarification, lithium extraction residue and lithium-loaded organic phase were obtained. The lithium extraction residue was then sent to the electrodialysis concentration section. The diketone extractant showed virtually no extraction of rubidium and cesium, while the extraction rates for lithium, sodium, and potassium were 97.2%, 0.8%, and 0.25%, respectively.

[0047] Lithium-loaded organic phase washing: The lithium-loaded organic phase was subjected to a three-stage countercurrent wash using 0.05 mol / L hydrochloric acid solution. The lithium-loaded organic phase and hydrochloric acid solution were mixed at a volume ratio of 10:1. After phase separation and clarification, sodium-potassium solution and washed lithium-loaded organic phase were obtained, respectively. The sodium-potassium washing rates were 98.2% and 99.8%, respectively, and the lithium loss rate was 5.3%.

[0048] Lithium-loaded organic phase washing and back-extraction: The lithium-loaded organic phase is washed and subjected to three-stage countercurrent back-extraction using 5 mol / L hydrochloric acid solution. The washed lithium-loaded organic phase is mixed with hydrochloric acid solution at a volume ratio of 20:1. After phase separation and clarification, lithium-rich back-extraction solution and empty organic phase are obtained respectively. The obtained empty organic phase is returned to the lithium extraction section as an extractant.

[0049] Lithium precipitation: Lithium carbonate is produced by adding sodium carbonate at 1.5 times the molar amount of lithium to the lithium-rich back-extraction solution. The lithium precipitation mother liquor is returned for decalcification of the leachate.

[0050] Electrodialysis Concentration Section: The lithium extraction residue is initially concentrated using electrodialysis. The produced fresh water is returned for washing the leaching slurry after the ore roasting process, and the concentrated water enters the cesium extraction section.

[0051] Cesium extraction: The concentrated lithium extraction residue was first adjusted to pH 12 using sodium hydroxide, and then a 0.5 mol / L 4-tert-butyl-2-(α-methylbenzyl)phenol (t-bambp)-sulfonated kerosene extraction system was used. The organic phase and concentrated water (i.e., the concentrated lithium extraction residue) were mixed at a volume ratio of 1:5 and subjected to a three-stage countercurrent extraction. After phase separation and clarification, cesium extraction residue and cesium-loaded organic phase were obtained separately. The cesium extraction residue entered the rubidium extraction section. t-bambp showed virtually no extraction for lithium, and the extraction rates for cesium, rubidium, sodium, and potassium were 98%, 6.3%, 0.54%, and 1.0%, respectively.

[0052] Washing of the cesium-loaded organic phase: The cesium-loaded organic phase was washed in a 5-stage countercurrent process using 1.10 mol / L hydrochloric acid solution. The cesium-loaded organic phase and hydrochloric acid solution were mixed at a volume ratio of 10:1. After phase separation and clarification, rubidium-containing washing solution and washed cesium-loaded organic phase were obtained separately. The washing rates of rubidium and sodium were both approximately 98%, the washing rate of potassium was over 99%, and the cesium loss rate was 15%.

[0053] Cesium-loaded organic phase back-extraction: The washed cesium-loaded organic phase was subjected to three-stage countercurrent back-extraction using 0.40 mol / L hydrochloric acid solution. The washed cesium-loaded organic phase and hydrochloric acid solution were mixed at a volume ratio of 30:1. After phase separation and clarification, cesium-rich back-extraction solution and empty organic phase were obtained respectively. The obtained empty organic phase was returned to the cesium extraction section as an extractant.

[0054] Preparation of cesium salt products: Cesium-rich back-extraction solution was evaporated and concentrated using MVR to obtain cesium chloride products.

[0055] Rubidium extraction: The pH of the cesium extraction residue was first adjusted to approximately 14 using sodium hydroxide. Then, a 1 mol / L 4-tert-butyl-2-(α-methylbenzyl)phenol and sulfonated kerosene extraction system was used. The organic phase and the cesium extraction residue were mixed at a 1:1 volume ratio and subjected to a three-stage countercurrent extraction. After phase separation and clarification, the rubidium extraction residue and the rubidium-loaded organic phase were obtained separately. The rubidium extraction residue was concentrated by MVR evaporation to open-circuit sodium and potassium. The extraction rates of rubidium, sodium, and potassium were 99%, 5.3%, and 7.1%, respectively.

[0056] Washing of the rubidium-supported organic phase: The rubidium-supported organic phase was subjected to a three-stage countercurrent wash using 2.60 mol / L hydrochloric acid solution. The rubidium-supported organic phase and hydrochloric acid solution were mixed at a volume ratio of 15:1. After phase separation and clarification, a sodium-potassium solution and the washed rubidium-supported organic phase were obtained, respectively. The sodium-potassium washing rates were 98% and 99%, respectively, and the rubidium loss rate was 15%.

[0057] Back-extraction of washed rubidium-loaded organic phase: The washed rubidium-loaded organic phase was subjected to four-stage countercurrent back-extraction using 0.60 mol / L hydrochloric acid solution. The washed rubidium-loaded organic phase and hydrochloric acid solution were mixed at a volume ratio of 15:1. After phase separation and clarification, rubidium-rich back-extraction solution and empty organic phase were obtained respectively. The obtained empty organic phase was returned to the rubidium extraction section for use.

[0058] Rubidium salt product preparation: Rubidium-rich back-extraction solution was evaporated and concentrated using MVR to obtain rubidium chloride product.

[0059] The elemental analysis results of the solution during the separation process of the above cascade extraction-washing-back-extraction-electrodialysis concentration process are shown in Table 2.

[0060] Table 2

[0061]

[0062]

[0063] Example 2

[0064] The method and process for the comprehensive recovery of lithium, rubidium, and cesium from lithium ore leaching solution provided in this embodiment are as follows: Figure 1 As shown in Table 3, a certain spodumene roasted sand leachate was used as raw material, and its main components are shown in Table 3.

[0065] Table 3

[0066] element Li Rb Cs K Na Ca <![CDATA[SO4 2- ]]> pH content 3.53 2.46 0.38 9.43 15.66 0.86 70.68 9.8

[0067] Decalcification of leachate: Sodium carbonate with a lithium equivalent of 80% is added to the leachate for decalcification, with a decalcification rate of over 99.5%. The decalcified solution then enters the lithium extraction section.

[0068] Lithium extraction: The decalcified liquid was subjected to a diketone-based extraction system combined with organophosphorus compounds and kerosene. The organic phase was mixed with the decalcified liquid at a 1:1 volume ratio and subjected to a three-stage countercurrent extraction. After phase separation and clarification, lithium extraction residue and lithium-loaded organic phase were obtained. The lithium extraction residue was then sent to the electrodialysis concentration section. The diketone extractant showed virtually no extraction of rubidium and cesium, while the extraction rates for lithium, sodium, and potassium were 95.2%, 0.55%, and 0.17%, respectively.

[0069] Lithium-loaded organic phase washing: The lithium-loaded organic phase was subjected to a three-stage countercurrent wash using a 0.05 mol / L sulfuric acid solution. The lithium-loaded organic phase was mixed with hydrochloric acid solution at a volume ratio of 7:1. After phase separation and clarification, a sodium-potassium solution and the washed lithium-loaded organic phase were obtained, respectively. The sodium-potassium washing rates were 99.5% and 99.8%, respectively, and the lithium loss rate was 3.0%.

[0070] Lithium-loaded organic phase washing and back-extraction: The lithium-loaded organic phase is washed and back-extracted in three stages using 5 mol / L sulfuric acid solution. The washed lithium-loaded organic phase is mixed with sulfuric acid solution at a volume ratio of 9:1. After phase separation and clarification, lithium-rich back-extraction solution and empty organic phase are obtained. The empty organic phase is returned to the lithium extraction section for use.

[0071] Lithium precipitation: Lithium carbonate is produced by adding sodium carbonate at twice the molar amount of lithium to the lithium-rich back-extraction solution. The lithium precipitation mother liquor is returned for decalcification of the leachate.

[0072] Electrodialysis Concentration Section: The lithium extraction residue is initially concentrated using electrodialysis. The produced fresh water is returned for washing the leaching slurry after the ore roasting process, and the concentrated water enters the cesium extraction section.

[0073] Cesium extraction: The concentrated water (i.e., the lithium extraction residue) is first adjusted to pH 12.5 with sodium hydroxide. Then, an extraction system of 0.8 mol / L 4-tert-butyl-2-(α-methylbenzyl)phenol (i.e., t-bambp) and sulfonated kerosene is used. The organic phase and concentrated water are mixed at a volume ratio of 1:3 and subjected to a four-stage countercurrent extraction. After phase separation and clarification, the cesium extraction residue and the cesium-loaded organic phase are obtained separately. The cesium extraction residue enters the rubidium extraction section. t-bambp has virtually no extraction effect on lithium, and the extraction rates for cesium, rubidium, sodium, and potassium are 97%, 3.7%, 0.68%, and 1.5%, respectively.

[0074] Washing of the cesium-loaded organic phase: The cesium-loaded organic phase was subjected to an 8-stage countercurrent wash using a 0.5 mol / L sulfuric acid solution. The cesium-loaded organic phase and sulfuric acid solution were mixed at a volume ratio of 5:1. After phase separation and clarification, rubidium-containing washing solution and the washed cesium-loaded organic phase were obtained separately. The washing rates of rubidium and sodium were both approximately 98%, and the washing rate of potassium was over 99%. The cesium loss rate was 13%.

[0075] Cesium-loaded organic phase back-extraction: The washed cesium-loaded organic phase was subjected to four-stage countercurrent back-extraction using 0.20 mol / L sulfuric acid solution. The washed cesium-loaded organic phase and sulfuric acid solution were mixed at a volume ratio of 20:1. After phase separation and clarification, cesium-rich back-extraction solution and empty organic phase were obtained respectively. The obtained empty organic phase was returned to the cesium extraction section for use.

[0076] Preparation of cesium salt products: Cesium-rich back-extraction solution was evaporated and concentrated using MVR to obtain cesium sulfate products.

[0077] Rubidium extraction: The pH of the cesium extraction residue was first adjusted to approximately 13.5 using sodium hydroxide. Then, a three-stage countercurrent extraction system was used, consisting of 2 mol / L 4-tert-butyl-2-(α-methylbenzyl)phenol and sulfonated kerosene. The organic phase was mixed with the cesium extraction residue at a volume ratio of 2:1. After phase separation and clarification, the rubidium extraction residue and the rubidium-loaded organic phase were obtained separately. The rubidium extraction residue was concentrated by MVR evaporation to open-circuit sodium and potassium. The extraction rates of rubidium, sodium, and potassium were 99%, 7.5%, and 10%, respectively.

[0078] Washing of the rubidium-loaded organic phase: The rubidium-loaded organic phase was subjected to a four-stage countercurrent wash using a 0.74 mol / L sulfuric acid solution. The rubidium-loaded organic phase and sulfuric acid solution were mixed at a volume ratio of 10:1. After phase separation and clarification, a sodium-potassium solution and the washed rubidium-loaded organic phase were obtained, respectively. The sodium-potassium washing rates were 98% and 99%, respectively, and the rubidium loss rate was 15%.

[0079] Back-extraction of washed rubidium-loaded organic phase: The washed rubidium-loaded organic phase was subjected to three-stage countercurrent back-extraction using 0.42 mol / L sulfuric acid solution. The washed rubidium-loaded organic phase and sulfuric acid solution were mixed at a volume ratio of 20:1. After phase separation and clarification, rubidium-rich back-extraction solution and empty organic phase were obtained respectively. The obtained empty organic phase was returned to the rubidium extraction section for use.

[0080] Rubidium salt product preparation: Rubidium-rich back-extraction solution was evaporated and concentrated using MVR to obtain rubidium sulfate product.

[0081] The elemental analysis results of the solution during the separation process of the above cascade extraction-washing-back-extraction-electrodialysis concentration process are shown in Table 4.

[0082] Table 4

[0083]

[0084]

[0085] For those skilled in the art, various corresponding changes and modifications can be made based on the above technical solutions and concepts, and all such changes and modifications should be included within the protection scope of the claims of this invention.

Claims

1. A method for the comprehensive recovery of lithium, rubidium, and cesium from lithium ore leaching solution, characterized in that, Includes the following steps: S1. Add sodium carbonate to the lithium ore leachate after impurity removal to remove calcium; S2. The calcium-removed liquid obtained in step S1 is mixed with the extractant and subjected to 1 to 10 stages of countercurrent extraction. After the extraction equilibrium is reached, the phases are separated to obtain the lithium extraction residue and the lithium-loaded organic phase. The lithium-loaded organic phase is transferred to step S3, and the lithium extraction residue is transferred to step S6. S3. The lithium-loaded organic phase obtained in step S2 is mixed with the washing solution and then subjected to 1 to 10 stages of countercurrent or crosscurrent washing to obtain a sodium-potassium washing solution and a washed lithium-loaded organic phase. The sodium-potassium washing solution is returned to step S2 for lithium extraction. S4. After mixing the washed lithium-loaded organic phase obtained in step S3 with the back-extraction solution, perform 1 to 10 stages of countercurrent or crosscurrent back-extraction. After the extraction equilibrium is reached, separate the phases to obtain lithium-rich back-extraction solution and empty organic phase. The empty organic phase is returned to step S2 as an extractant to participate in the extraction. S5. Add sodium carbonate to the lithium-rich back-extraction solution obtained in step S4 to precipitate lithium and obtain lithium precipitation mother liquor and lithium carbonate product. The lithium precipitation mother liquor is returned to step S1 for decalcification of lithium ore leaching solution. S6. The lithium extraction residue obtained in step S2 is concentrated by electrodialysis to obtain fresh water and concentrated water. S7. After adjusting the pH of the concentrated water obtained in step S6, mix it with the extractant and perform 1 to 10 stages of countercurrent extraction. After the extraction reaches equilibrium, separate the phases to obtain the cesium-loaded organic phase and the cesium extraction residue. The cesium-loaded organic phase is transferred to step S8, and the cesium extraction residue is transferred to step S11. S8. After mixing the cesium-loaded organic phase obtained in step S7 with the washing solution, perform 1 to 10 stages of countercurrent or crosscurrent washing to obtain a rubidium-containing washing solution and a washed cesium-loaded organic phase. The rubidium-containing washing solution is returned to step S7 to continue cesium extraction. S9. The washed cesium-loaded organic phase obtained in step S8 is mixed with the back-extraction solution and subjected to 1 to 10 stages of countercurrent or crosscurrent back-extraction. After the extraction equilibrium is reached, the phases are separated to obtain a cesium-rich back-extraction solution and an empty organic phase. The empty organic phase is returned to step S7 as an extractant to participate in the extraction. S10. Evaporate and crystallize the cesium-rich back-extraction solution obtained in step S9 to obtain the cesium salt product; S11. Adjust the pH of the cesium extraction residue obtained in step S7 and then mix it with the extractant for 1 to 10 stages of countercurrent extraction. After extraction equilibrium, separate the phases to obtain rubidium extraction residue and rubidium-supported organic phase. Evaporate and crystallize the rubidium extraction residue to open the sodium and potassium salts. S12. The rubidium-carrying organic phase obtained in step S11 is mixed with the washing liquid and then subjected to 1 to 10 stages of countercurrent or crosscurrent washing to obtain a sodium-potassium washing liquid and a washed rubidium-carrying organic phase. The sodium-potassium washing liquid is returned to step S11 for rubidium extraction. S13. The washed rubidium-loaded organic phase obtained in step S12 is mixed with the back-extraction solution and subjected to 1 to 10 stages of countercurrent or crosscurrent back-extraction. After the extraction equilibrium is reached, the phases are separated to obtain a rubidium-rich back-extraction solution and an empty organic phase. The empty organic phase is returned to step S11 as an extractant to participate in the extraction. S14. Evaporate and crystallize the rubidium-rich back-extraction solution obtained in step S13 to obtain the rubidium salt product. In step S3, the lithium-loaded organic phase and the washing solution are mixed in a volume ratio of 1:1 to 20:1, and the single-stage washing time is 1 to 30 minutes; the washing solution is one or more of hydrochloric acid, sulfuric acid or nitric acid solutions with an acid concentration of 0.05 to 0.5 mol / L.

2. The method according to claim 1, characterized in that, In step S2, the extractant and the decalcified liquid are mixed at a volume ratio of 1:10 to 10:1, and the single-stage extraction time is 1 to 30 minutes; the extractant is a combination of diketone compounds, organophosphorus compounds and kerosene.

3. The method according to claim 1, characterized in that, In step S4, the washing lithium-loaded organic phase and the back-extraction solution are mixed in a volume ratio of 1:1 to 50:1, and the single-stage back-extraction time is 1 to 30 minutes; the back-extraction solution is one or more of hydrochloric acid, sulfuric acid or nitric acid solutions with an acid concentration of 5 to 15 mol / L.

4. The method according to claim 1, characterized in that, In step S7, the concentrated water is adjusted to pH 9-13 by adding alkali; the extractant and the pH-adjusted concentrated water are mixed in a volume ratio of 1:10-10:1, and the single-stage extraction time is 1-30 min; the extractant is a mixture of 4-tert-butyl-2-(α-methylbenzyl)phenol and sulfonated kerosene, and the concentration of 4-tert-butyl-2-(α-methylbenzyl)phenol is 0.1-1 mol / L.

5. The method according to claim 1, characterized in that, In step S8, the cesium-carrying organic phase and the washing solution are mixed in a volume ratio of 1:1 to 20:1, and the single-stage washing time is 1 to 30 minutes; the washing solution is one or more of hydrochloric acid, sulfuric acid or nitric acid solutions with an acid concentration of 0.5 to 2 mol / L.

6. The method according to claim 1, characterized in that, In step S9, the washing cesium-carrying organic phase and the back-extraction solution are mixed in a volume ratio of 1:1 to 50:1, and the single-stage back-extraction time is 1 to 30 minutes; the back-extraction solution is one or more of hydrochloric acid, sulfuric acid or nitric acid solutions with an acid concentration of 0.1-1 mol / L.

7. The method according to claim 1, characterized in that, In step S11, the pH of the cesium extraction residue is adjusted to 11-14 by adding alkali; the extractant is a mixture of 4-tert-butyl-2-(α-methylbenzyl)phenol and sulfonated kerosene, and the concentration of 4-tert-butyl-2-(α-methylbenzyl)phenol is 1-5 mol / L; the extractant and the pH-adjusted cesium extraction residue are mixed at a volume ratio of 1:10 to 10:1, and the single-stage extraction time is 1-30 min.

8. The method according to claim 1, characterized in that, In step S12, the rubidium-carrying organic phase and the washing solution are mixed in a volume ratio of 1:1 to 20:1, and the single-stage washing time is 1 to 30 minutes; the washing solution is one or more of hydrochloric acid, sulfuric acid or nitric acid solutions with an acid concentration of 0.5 to 5 mol / L.

9. The method according to claim 1, characterized in that, In step S13, the washing rubidium-carrying organic phase and the back-extraction solution are mixed in a volume ratio of 1:1 to 50:1, and the single-stage back-extraction time is 1 to 30 minutes; the back-extraction solution is one or more of hydrochloric acid, sulfuric acid or nitric acid solutions with an acid concentration of 0.3-2 mol / L.

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