A method for selective extraction of lithium from a lithium ore alkaline leach solution

Abstract

The present application relates to a kind of selective extraction method of lithium in lithium ore alkali leaching solution.The selective extraction method includes: mixing lithium ore alkali leaching solution with composite extractant, extraction, obtain loaded organic phase;The loaded organic phase is sequentially eluted and back extraction, and back extraction solution is obtained;Precipitant is added to the back extraction solution, precipitation reaction, solid-liquid separation, and lithium carbonate product is obtained;The composite extractant includes extractant and diluent, and the extractant includes salicylate compound and phosphate compound.The present application uses salicylate compound and phosphate compound as extractant, and forms composite extractant with diluent, and the composite extractant system has the advantages of high selectivity, no alkali consumption, fast phase separation, no emulsification, can be recycled and reused, and the yield of lithium carbonate prepared is high, which is very suitable for large-scale industrialization of lithium extraction.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal separation technology, specifically to the selective extraction of lithium, and more particularly to a method for the selective extraction of lithium from alkaline leaching solutions of lithium ore. Background Technology

[0002] Lithium is a strategically important new energy source and strategic metal. Li₂CO₃ is the main raw material for preparing other high-purity lithium alloys and lithium compounds, and is the most widely used lithium compound in the lithium salt industry. Lithium ore refining or brine lake lithium extraction processes first obtain a lithium-containing solution. After impurity removal, it undergoes a precipitation reaction with carbonates. After washing and drying, lithium carbonate is obtained. In existing technologies, extraction is commonly used to remove impurities and extract lithium from the lithium-containing solution.

[0003] CN111099641A discloses a method for extracting lithium ions to prepare high-purity lithium carbonate. The method employs an extraction-crystallization process to extract lithium ions and prepare high-purity lithium carbonate, specifically using phosphate ester-type extractants, ketone extractants, or macrocyclic polyether extractants. A diluent is added and mixed to prepare a low-viscosity organic phase for extraction. Extraction is then performed. Alkaline metal bicarbonates and their carbonates, carbonic acid, and ammonium bicarbonate brine are used as back-extraction agents to obtain an aqueous solution of lithium bicarbonate. The solution is then heat-sinked, crystallized, and washed and dried to obtain lithium bicarbonate crystals with a purity of over 99.9%.

[0004] CN111304462A discloses a compound extractant and a method for extracting lithium from lithium ore leachate. The compound extractant includes a primary extractant and a co-extractant. The primary extractant is p204, and the co-extractant is selected from any one or more of TBP, TOPO, and TRPO. The volume ratio of the primary extractant to the co-extractant is (4-6):(1-3). GV-18A is used as the diluent, which has the advantages of high extraction efficiency.

[0005] CN118206141A discloses a process for preparing battery-grade lithium carbonate by extracting mother liquor after lithium precipitation. The process uses a mixture of organic phosphoric acid compounds and organic sulfoxide compounds as a composite extractant. The composite extractant is added to the mother liquor after lithium precipitation, and the mixture undergoes four stages of countercurrent continuous extraction and separation to obtain a loaded organic phase and raffinate. The loaded organic phase is then subjected to two stages of countercurrent continuous back-extraction to obtain a lithium-containing lithium sulfate back-extraction solution. After removing oil from the lithium sulfate back-extraction solution using an oil removal system, lithium is precipitated, centrifuged, and dried to obtain battery-grade lithium carbonate.

[0006] Existing extraction systems for lithium extraction from lithium-containing solutions often require large amounts of organic solvents as diluents, leading to significant solvent losses. Furthermore, some techniques involve lengthy extraction times and require further improvement in extraction efficiency, hindering the rapid separation capabilities needed for industrial production. Additionally, some methods rely on diketone or ionic liquid extractants, resulting in high costs that are difficult to meet the requirements for large-scale, low-cost industrial applications.

[0007] Therefore, it is of great significance to provide a lithium extraction method that is fast, uses low amounts of organic solvents, has low extraction agent costs, and is easy to industrialize. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a selective extraction method for lithium from alkaline leaching solutions of lithium ore. This invention employs a combination of salicylates and phosphates as extractants, which, together with a diluent, form a composite extractant system. This composite extractant system offers advantages such as high selectivity, no alkali consumption, rapid phase separation, and non-emulsification. It can be recycled repeatedly, and the resulting lithium carbonate yield is high, making it highly suitable for large-scale industrial lithium extraction.

[0009] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for selective extraction of lithium from an alkaline leaching solution of lithium ore, the selective extraction method comprising: A mixed lithium ore alkaline leaching solution is extracted with a composite extractant to obtain a loaded organic phase; the loaded organic phase is then eluted and back-extracted sequentially to obtain a back-extracting solution; a precipitant is added to the back-extracting solution, a precipitation reaction is initiated, and solid-liquid separation is performed to obtain a lithium carbonate product; the composite extractant includes an extractant and a diluent, and the extractant includes salicylates and phosphates.

[0010] This invention uses salicylates and phosphates as extractants, which together with a diluent form a composite extractant system. This composite extractant system has the advantages of high selectivity, no alkali consumption, fast phase separation, and no emulsification. It can be recycled and reused repeatedly, and the resulting lithium carbonate yield is high, making it very suitable for large-scale industrial lithium extraction.

[0011] In this invention, O / A mentioned during extraction, elution, or back-extraction refers to the volume ratio of the oil phase to the aqueous phase.

[0012] Preferably, the salicylate ester compound includes any one or a combination of at least two of phenyl salicylate, isoamyl salicylate, isooctyl salicylate, benzyl salicylate, isodecanyl salicylate, or phenethyl salicylate.

[0013] Preferably, the phosphate ester compound includes any one or a combination of at least two of the following: tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, di(2-ethylhexyl)phenyl phosphate, or 2-ethylhexyl diphenyl phosphate.

[0014] Preferably, in the composite extractant, the molar ratio of salicylate esters to phosphate esters is (0.5~2):1.

[0015] Preferably, the diluent comprises any one of kerosene, sulfonated kerosene, liquid paraffin, D80, 260# solvent oil, Escaid110, butyl benzoate, heptyl acetate, octanol, dodecyl alcohol, 4-methyl-2-pentanone, diisobutyl ketone, S150, or toluene, or a combination of at least two that are miscible in any volume ratio.

[0016] Preferably, the concentration of the composite extractant is 0.1 mol / L to 1 mol / L.

[0017] Preferably, the O / A ratio of the extracted material is (0.1~5):1.

[0018] Preferably, the extraction temperature is 20℃~60℃.

[0019] Preferably, the extraction time is 5 min to 60 min.

[0020] Preferably, the extraction is performed using a 1- to 5-stage countercurrent extraction process.

[0021] Preferably, the eluent used for elution includes any one or a combination of at least two of hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, oxalic acid, acetic acid, citric acid, and tartaric acid.

[0022] Preferably, the concentration of the eluent used in the elution is 0 mol / L to 1 mol / L.

[0023] Preferably, the elution O / A ratio is (1~20):1.

[0024] Preferably, the elution temperature is 20℃~60℃.

[0025] Preferably, the elution time is 5 min to 60 min.

[0026] Preferably, the elution process employs a 1-5 stage countercurrent elution method.

[0027] Preferably, the back-extraction agent used in the back-extraction includes any one or a combination of at least two of hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, oxalic acid, acetic acid, citric acid and tartaric acid.

[0028] Preferably, the concentration of the back-extraction agent used in the back-extraction is 1 mol / L to 5 mol / L.

[0029] Preferably, the O / A ratio of the back-extraction is (1~20):1.

[0030] Preferably, the back-extraction temperature is 20℃~60℃.

[0031] Preferably, the back-extraction time is 5 min to 60 min.

[0032] Preferably, the back-extraction is performed using 1- to 5-stage countercurrent back-extraction.

[0033] Preferably, the precipitant comprises any one or a combination of at least two of sodium carbonate, ammonium carbonate, sodium bicarbonate, or ammonium bicarbonate.

[0034] Preferably, the concentration of the precipitant added to the back-extraction solution is 0.1 mol / L to 2.5 mol / L.

[0035] Preferably, the precipitation reaction is carried out at a temperature of 80°C to 100°C.

[0036] Preferably, the precipitation reaction time is 60 min to 120 min.

[0037] Preferably, the temperature for solid-liquid separation is 70℃~100℃.

[0038] Preferably, the Na in the lithium ore alkaline leaching solution is used. + K + and Li + Mass concentration meter, c(Na) + ):c(Li + )≤40, c(K) + ):c(Li + )≤20.

[0039] Preferably, the pH of the lithium ore alkali leaching solution is 10-14.

[0040] Compared with the prior art, the present invention has the following beneficial effects: This invention employs a combination of salicylates and phosphates as extractants, which, together with a diluent, form a composite extractant system. This composite extractant system offers advantages such as high selectivity, no alkali consumption, rapid phase separation, and non-emulsification. It can be recycled repeatedly, and the resulting lithium carbonate yield is high, making it highly suitable for large-scale industrial lithium extraction. Detailed Implementation

[0041] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0042] The scope of this invention can be defined by lower and upper limits. The selected lower and upper limits define the boundaries of a specific range. The range defined in this way can be defined by the inclusion or exclusion of endpoints. Any endpoint can be independently selected for inclusion or exclusion, and all lower and upper limits can be arbitrarily combined to form new ranges. That is, any lower limit can be combined with any upper limit to form an effective range. For example, if the ranges of 60~120 and 80~110 are listed for specific parameters, it should be understood that the ranges of 60~110 and 80~120 also fall within the scope of this invention. In addition, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are also listed, then all ranges of 1~3, 1~4, 1~5, 2~3, 2~4 and 2~5 fall within the scope of this invention. In this invention, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between 0 and 5 have been fully listed in this document, and "0~5" is only a shortened representation of this set of numerical combinations. When a parameter is expressed as an integer ≥2, it is equivalent to listing positive integers that meet the requirements, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. When a parameter is expressed as an integer selected from "2~10", it is equivalent to listing any integer among 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0043] In this invention, "a combination of at least two" refers to a quantity greater than or equal to 2 unless otherwise specified. For example, "any one or a combination of at least two" means that any one of the listed items can be selected, or a combination of at least two of the listed items formed in a manner that does not conflict and enables the implementation of this invention. In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" cover any one of two or more related listed items, as well as any and all combinations of the related listed items. The arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" means a set consisting of A, B, and combinations of A and B, where "containing A and / or B" can be understood, depending on the context of the statement, as containing A, containing B, or simultaneously containing both A and B. In this invention, "optional" means that the corresponding feature, component, step or solution is not necessary, that is, it is selected from either "with" or "without". If there are multiple "optional" limitations in a technical solution, unless otherwise specified and there is no technical conflict or mutual constraint, each "optional" limitation is independent and does not affect the others.

[0044] In this invention, technical features or solutions described using open-ended terms such as "comprising" or "including" do not exclude additional non-conflicting elements beyond the listed elements unless otherwise specified. They are considered to disclose both closed-ended features or solutions consisting solely of the listed elements and open-ended features or solutions that may include additional non-conflicting elements beyond the listed elements. For example, if A includes a1, a2, and a3, unless otherwise specified, this means that A can consist only of a1, a2, and a3, or it can include other non-conflicting elements based on a1, a2, and a3. This corresponds to the disclosure of technical solutions such as "A consists of a1, a2, and a3," "A is selected from a1, a2, and a3," and "A not only includes a1, a2, and a3, but may also include other non-conflicting elements." All embodiments and optional embodiments of this invention, unless otherwise specified and without technical conflict, can be combined to form new technical solutions, and such combinations fall within the scope of this invention. The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various locations throughout the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this invention can be combined with other embodiments that do not conflict with the technology. The ordinal numbers "first," "second," "third," and "fourth," etc., used in the expressions "first aspect," "second aspect," "third aspect," and "fourth aspect" in this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly specifying the importance or quantity of the indicated technical features. They serve only as a non-exhaustive enumeration and do not constitute a closed limitation on quantity.

[0045] In this invention, the order in which the steps are written in the methods described in each embodiment does not imply a strict execution order. The actual execution order of each step should be determined based on its function and possible internal logic. Unless otherwise specified, all steps of this invention can be executed in the order they are written, or in any order without technical conflict. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) executed sequentially, or it may include steps (b) and (a) executed sequentially. If the method also includes step (c), then step (c) can be added to the method in any order without conflict, including but not limited to the execution order of steps (a), (b), and (c), steps (a), (c), and (b), steps (c), (a), and (b), etc.

[0046] In one specific embodiment, the present invention provides a method for selective extraction of lithium from an alkaline leaching solution of lithium ore, the selective extraction method comprising: A mixed lithium ore alkaline leaching solution is extracted with a composite extractant to obtain a loaded organic phase; the loaded organic phase is then eluted and back-extracted sequentially to obtain a back-extracting solution; a precipitant is added to the back-extracting solution, a precipitation reaction is initiated, and solid-liquid separation is performed to obtain a lithium carbonate product; the composite extractant includes an extractant and a diluent, and the extractant includes salicylates and phosphates.

[0047] This invention uses a combination of salicylates and phosphates as extractants. The salicylates act as the primary extractant, selectively extracting lithium from the alkaline leaching solution of lithium ore. The phosphates act as co-extractants; they do not have extraction properties on their own, but when used in combination with the salicylates, they significantly improve the extraction efficiency and selectivity of lithium. Furthermore, the compound system exhibits a significant decrease in viscosity, an increase in organic phase loading capacity, improved phase separation performance, and a synergistic intermolecular solubilization effect, eliminating the need for large amounts of inert diluents to reduce viscosity, solubilize, and improve phase separation.

[0048] The extractant and diluent constitute a composite extractant system. The composite extractant system has the advantages of high selectivity, no alkali consumption, fast phase separation, and no emulsification. It can be recycled and reused repeatedly, and the lithium carbonate yield obtained is high, making it very suitable for large-scale industrial lithium extraction.

[0049] In some embodiments, the salicylate ester compound includes any one or a combination of at least two of phenyl salicylate, isoamyl salicylate, isooctyl salicylate, benzyl salicylate, isodecanyl salicylate, or phenethyl salicylate.

[0050] In some embodiments, the phosphate ester compound includes any one or a combination of at least two of the following: tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, di(2-ethylhexyl)phenyl phosphate, or 2-ethylhexyl diphenyl phosphate.

[0051] In some embodiments, the molar ratio of salicylates to phosphates in the composite extractant is (0.5~2):1, for example, 0.5:1, 0.75:1, 1:1, 1.25:1, 1.5:1, 1.75:1, or 2:1. When the molar ratio of salicylates to phosphates in the composite extractant is within a suitable range, it can significantly improve the lithium extraction efficiency and ensure high selectivity for lithium extraction, while keeping costs under control to meet the requirements of industrial-scale lithium extraction.

[0052] In some embodiments, the diluent comprises any one of kerosene, sulfonated kerosene, liquid paraffin, D80, 260# solvent oil, Escaid 110, butyl benzoate, heptyl acetate, octanol, dodecyl alcohol, 4-methyl-2-pentanone, diisobutyl ketone, S150, or toluene, or a combination of at least two that are miscible in any volume ratio.

[0053] In some embodiments, the concentration of the composite extractant is 0.1 mol / L to 1 mol / L, for example, it can be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L or 1 mol / L.

[0054] In some embodiments, the extracted O / A ratio is (0.1~5):1, for example, it can be 0.1:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1 or 5:1.

[0055] In some embodiments, the extraction temperature is 20°C to 60°C, for example, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C.

[0056] In some embodiments, the extraction time is 5 min to 60 min, for example, 5 min, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min.

[0057] In some embodiments, the extraction employs a 1- to 5-stage countercurrent extraction process, for example, a 1-stage, 2-stage, 3-stage, 4-stage, or 5-stage extraction.

[0058] In some embodiments, the eluent used for elution includes any one or a combination of at least two of hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, oxalic acid, acetic acid, citric acid, and tartaric acid.

[0059] In some embodiments, the concentration of the eluent used for elution is 0 mol / L to 1 mol / L, for example, it can be 0 mol / L, 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L or 1 mol / L.

[0060] In some embodiments, the elution O / A ratio is (1~20):1, for example, it can be 1:1, 2:1, 4:1, 6:1, 8:1, 10:1, 12:1, 14:1, 16:1, 18:1 or 20:1.

[0061] In some embodiments, the elution temperature is 20°C to 60°C, for example, it can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C.

[0062] In some embodiments, the elution time is 5 min to 60 min, for example, it can be 5 min, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min.

[0063] In some embodiments, the elution is performed using 1 to 5 stages of countercurrent elution, for example, it can be 1, 2, 3, 4 or 5 stages.

[0064] In some embodiments, the back-extraction agent used includes any one or a combination of at least two of hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, oxalic acid, acetic acid, citric acid, and tartaric acid.

[0065] In some embodiments, the concentration of the back-extraction agent used in the back-extraction is 1 mol / L to 5 mol / L, for example, it can be 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L.

[0066] In some implementations, the O / A ratio of the back-extraction is (1~20):1, for example, it can be 1:1, 2:1, 4:1, 6:1, 8:1, 10:1, 12:1, 14:1, 16:1, 18:1 or 20:1.

[0067] In some embodiments, the back-extraction temperature is 20°C to 60°C, for example, it can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C.

[0068] In some embodiments, the back-extraction time is 5 min to 60 min, for example, it can be 5 min, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min.

[0069] In some implementations, the back-extraction employs 1 to 5 stages of countercurrent back-extraction, for example, it can be 1 stage, 2 stages, 3 stages, 4 stages or 5 stages.

[0070] In some embodiments, the precipitant includes any one or a combination of at least two of sodium carbonate, ammonium carbonate, sodium bicarbonate, or ammonium bicarbonate.

[0071] In some embodiments, the concentration of the precipitant added to the back-extraction solution is 0.1 mol / L to 2.5 mol / L, for example, it can be 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L or 2.5 mol / L.

[0072] In some embodiments, the temperature of the precipitation reaction is 80°C to 100°C, for example, 80°C, 85°C, 90°C, 95°C or 100°C.

[0073] In some embodiments, the precipitation reaction time is 60 min to 120 min, for example, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min or 120 min.

[0074] In some embodiments, the temperature for solid-liquid separation is 70°C to 100°C, for example, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C.

[0075] In some embodiments, Na in the lithium ore alkaline leaching solution + K + and Li + Mass concentration meter, c(Na) + ):c(Li + )≤40, for example, it can be 20, 25, 30, 35 or 40, c(K) + ):c(Li + )≤20, for example, it can be 5, 10, 15 or 20.

[0076] In this invention, unless otherwise specified, the Na in the lithium ore alkaline leaching solution is... + K + and Li + The unit of mass concentration is g / L.

[0077] In some embodiments, the pH of the lithium ore alkaline leaching solution is 10 to 14, for example, it can be 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5 or 14.

[0078] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0079] Example 1 This embodiment provides a method for selective extraction of lithium from an alkaline leaching solution of lithium ore. The selective extraction method includes: (1) A composite extractant with a concentration of 0.3 mol / L was prepared by mixing phenyl salicylate and tributyl phosphate in a molar ratio of 1:1 as extractants and sulfonated kerosene as a diluent.

[0080] (2) The lithium ore alkali leaching solution and the composite extractant were mixed at an O / A ratio of 1:1 and subjected to three-stage countercurrent extraction at a temperature of 25°C for 10 min. After the extraction reached equilibrium, the mixture was allowed to stand, and the aqueous phase and the supported organic phase were separated. The lithium ore alkali leaching solution contained 2.13 g / L of Li. + 40.65 g / L Na + 10.93 g / L of K + The pH value is 14. (3) The loaded organic phase was mixed with 0.1 mol / L hydrochloric acid at an O / A ratio of 5:1 and subjected to three-stage countercurrent elution. The elution temperature was 25℃ and the time was 10 min. After the elution reached equilibrium, the mixture was allowed to stand and the eluted organic loaded phase and the eluted aqueous phase were separated. (4) According to the O / A ratio of 10:1, the organic supported phase after elution was subjected to two-stage countercurrent back-extraction using hydrochloric acid with a concentration of 5 mol / L. The back-extraction temperature was 25℃ and the time was 10 min. After the back-extraction reached equilibrium, the mixture was allowed to stand and the phases were separated to obtain the back-extraction solution. (5) Add sodium carbonate to the back-extraction solution. The concentration of sodium carbonate is 2.13 mol / L. The precipitation reaction is carried out under stirring. The precipitation reaction temperature is 95℃ and the time is 70 min. Then filter at 90℃, wash the solid product with saturated lithium carbonate solution, and dry to obtain lithium carbonate product.

[0081] Example 2 This embodiment provides a method for selective extraction of lithium from an alkaline leaching solution of lithium ore. The selective extraction method includes: (1) A composite extractant with a concentration of 0.4 mol / L was prepared by mixing isoamyl salicylate and triphenyl phosphate in a molar ratio of 0.5:1 with toluene as a diluent.

[0082] (2) The lithium ore alkali leaching solution and the composite extractant were mixed at an O / A ratio of 1:1 and subjected to three-stage countercurrent extraction at a temperature of 25°C for 10 min. After the extraction reached equilibrium, the mixture was allowed to stand, and the aqueous phase and the supported organic phase were separated. The lithium ore alkali leaching solution contained 1.76 g / L of Li. + 30.43 g / L Na + 13.25 g / L of K + The pH value is 12; (3) The loaded organic phase was mixed with 0.01 mol / L hydrochloric acid at an O / A ratio of 2:1 and subjected to three-stage countercurrent elution. The elution temperature was 25℃ and the time was 10 min. After the elution reached equilibrium, the mixture was allowed to stand and the eluted organic loaded phase and the eluted aqueous phase were separated. (4) According to the O / A ratio of 15:1, the organic supported phase after elution was subjected to three-stage countercurrent back-extraction using hydrochloric acid with a concentration of 3 mol / L. The back-extraction temperature was 25℃ and the time was 10 min. After the back-extraction reached equilibrium, the mixture was allowed to stand and the phases were separated to obtain the back-extraction solution. (5) Add sodium carbonate to the back-extraction solution. The concentration of sodium carbonate is 1.91 mol / L. The precipitation reaction is carried out under stirring. The precipitation reaction temperature is 95℃ and the time is 80 min. Then filter at 95℃, wash the solid product with saturated lithium carbonate solution, and dry to obtain lithium carbonate product.

[0083] Example 3 This embodiment provides a method for selective extraction of lithium from an alkaline leaching solution of lithium ore. The selective extraction method includes: (1) A composite extractant with a concentration of 0.4 mol / L was prepared by mixing isooctyl salicylate and tributyl phosphate in a molar ratio of 2:1 with toluene as a diluent.

[0084] (2) The lithium ore alkali leaching solution and the composite extractant were mixed at an O / A ratio of 1:1 and subjected to three-stage countercurrent extraction at a temperature of 25°C for 10 min. After the extraction reached equilibrium, the mixture was allowed to stand, and the aqueous phase and the supported organic phase were separated. The lithium ore alkali leaching solution contained 2.35 g / L of Li. + 48.50 g / L Na + 11.20 g / L of K + The pH value is 14. (3) The loaded organic phase was mixed with 0.2 mol / L hydrochloric acid at an O / A ratio of 10:1 and subjected to three-stage countercurrent elution. The elution temperature was 25℃ and the time was 10 min. After the elution reached equilibrium, the mixture was allowed to stand and the eluted organic loaded phase and the eluted aqueous phase were separated. (4) According to the O / A ratio of 20:1, the organic supported phase after elution was subjected to three-stage countercurrent back-extraction using hydrochloric acid with a concentration of 4 mol / L. The back-extraction temperature was 25℃ and the time was 10 min. After the back-extraction reached equilibrium, the mixture was allowed to stand and the phases were separated to obtain the back-extraction solution. (5) Add sodium carbonate to the back-extraction solution. The concentration of sodium carbonate is 1.91 mol / L. The precipitation reaction is carried out under stirring. The precipitation reaction temperature is 80℃ and the time is 120 min. Then filter at 80℃, wash the solid product with saturated lithium carbonate solution, and dry to obtain lithium carbonate product.

[0085] Example 4 This embodiment provides a method for selective extraction of lithium from an alkaline leaching solution of lithium ore. The selective extraction method includes: (1) A composite extractant with a concentration of 0.3 mol / L was prepared by mixing isoamyl salicylate and trioctyl phosphate in a molar ratio of 1:1 with toluene as a diluent.

[0086] (2) The lithium ore alkali leaching solution and the composite extractant were mixed at an O / A ratio of 1:1 and subjected to three-stage countercurrent extraction at a temperature of 25°C for 10 min. After the extraction reached equilibrium, the mixture was allowed to stand, and the aqueous phase and the supported organic phase were separated. The lithium ore alkali leaching solution contained 1.80 g / L of Li. + 54.20 g / L Na + 11.50 g / L of K + The pH value is 12; (3) The loaded organic phase was mixed with 0.01 mol / L hydrochloric acid at an O / A ratio of 4:1 and subjected to three-stage countercurrent elution. The elution temperature was 25℃ and the time was 10 min. After the elution reached equilibrium, the mixture was allowed to stand and the eluted organic loaded phase and the eluted aqueous phase were separated. (4) According to the O / A ratio of 10:1, the organic loaded phase after elution was subjected to five-stage countercurrent back-extraction using hydrochloric acid with a concentration of 4 mol / L. The back-extraction temperature was 25℃ and the time was 10 min. After the back-extraction reached equilibrium, the mixture was allowed to stand and the phases were separated to obtain the back-extraction solution. (5) Add sodium carbonate to the back-extraction solution. The concentration of sodium carbonate is 2.48 mol / L. The precipitation reaction is carried out under stirring. The precipitation reaction temperature is 100℃ and the time is 60 min. Then filter at 100℃, wash the solid product with saturated lithium carbonate solution, and dry to obtain lithium carbonate product.

[0087] Example 5 This embodiment provides a selective extraction method for lithium in an alkaline leaching solution of lithium ore. Except for step (2), in which the alkaline leaching solution of lithium ore is mixed with the composite extractant at an O / A ratio of 0.5:1 and subjected to four-stage countercurrent extraction, the selective extraction method is the same as in Example 1.

[0088] Example 6 This embodiment provides a selective extraction method for lithium in an alkaline leaching solution of lithium ore. Except for step (2), in which the alkaline leaching solution of lithium ore and the composite extractant are mixed at an O / A ratio of 1.5:1, the selective extraction method is the same as in Example 2.

[0089] Example 7 This embodiment provides a selective extraction method for lithium from an alkaline leaching solution of lithium ore. The selective extraction method is the same as that in Example 3, except that the pH of the alkaline leaching solution of lithium ore is 10.

[0090] Example 8 This embodiment provides a selective extraction method for lithium from an alkaline leaching solution of lithium ore. The selective extraction method is the same as that in Example 4, except that the pH of the alkaline leaching solution of lithium ore is 14.

[0091] Example 9 This embodiment provides a selective extraction method for lithium in the alkaline leaching solution of lithium ore. Except for step (3), in which the loaded organic phase is mixed with 0.01 mol / L hydrochloric acid at an O / A ratio of 3:1 and subjected to three-stage countercurrent elution, the selective extraction method is the same as in Example 4.

[0092] Example 10 This embodiment provides a selective extraction method for lithium in the alkaline leaching solution of lithium ore. Except for step (4), in which hydrochloric acid with a concentration of 2 mol / L is used to perform five-stage countercurrent back-extraction on the eluted organic supported phase, the selective extraction method is the same as in Example 4.

[0093] Example 11 This embodiment provides a selective extraction method for lithium in an alkaline leaching solution of lithium ore. Except for step (5) where the concentration of sodium carbonate is 1.62 mol / L, the selective extraction method is the same as in Example 4.

[0094] Example 12 This embodiment provides a selective extraction method for lithium in an alkaline leaching solution of lithium ore. Except for step (1), in which the molar ratio of isoamyl salicylate to trioctyl phosphate in the extractant is 2.5:1, the selective extraction method is the same as in Example 4.

[0095] Comparative Example 1 This comparative example provides a selective extraction method for lithium in an alkaline leaching solution of lithium ore. Except for step (1), in which only isoamyl salicylate is used as the extractant, the selective extraction method is the same as in Example 4.

[0096] Comparative Example 2 This comparative example provides a selective extraction method for lithium in the alkaline leaching solution of lithium ore. Except for step (1), which uses only trioctyl phosphate as the extractant, the selective extraction method is the same as that in Example 4.

[0097] Performance testing: In the selective extraction method for lithium from the alkaline leaching solution of lithium ore provided in all the above embodiments and comparative examples, the Li in the extraction aqueous phase obtained in step (2) is... + Na+ and K + The concentration of Li was tested and the concentration of Li was calculated. + Na + and K + The extraction rate was measured, and the test results are shown in Table 1.

[0098] In the selective extraction method for lithium from the alkaline leaching solution of lithium ore provided in all the above embodiments and comparative examples, the Li in the eluted aqueous phase obtained in step (3) is... + Na + and K + The concentration of Li was tested and the concentration of Li was calculated. + Na + and K + The elution rate was measured, and the test results are shown in Table 2.

[0099] In the selective extraction method for lithium from the alkaline leaching solution of lithium ore provided in all the above embodiments and comparative examples, the Li in the back-extraction solution after step (4) is... + The concentration of lithium carbonate was tested, and the yield of the lithium carbonate product obtained in step (5) was also tested. The yield = mass of lithium in the lithium carbonate product / mass of lithium in the lithium ore alkali leaching solution × 100%. The test results are shown in Table 3.

[0100] Table 1 Table 2 Table 3 Based on the test results of Examples 1 to 11 in Tables 1 to 3, compared with the single type of extractant in Comparative Example 1, the present invention uses a combination of salicylates and phosphates as extractants, which together with a diluent form a composite extractant. The composite extractant system has the advantages of high selectivity, no alkali consumption, fast phase separation, and no emulsification. It can be recycled and reused repeatedly, and the yield of lithium carbonate obtained is high, making it very suitable for large-scale industrial lithium extraction.

[0101] According to the test results of Comparative Example 2, phosphate esters do not have the function of extracting lithium on their own. However, when used as an extractant in combination with salicylate ester extractants, they can significantly improve the extraction efficiency and selectivity of lithium.

[0102] Based on the test results of Examples 4 and 12 in Table 1, this invention not only uses salicylate compounds and phosphate compounds in combination, but also adjusts their molar ratio to further improve the yield and extraction efficiency of lithium carbonate.

[0103] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for selective extraction of lithium from an alkaline leaching solution of lithium ore, characterized in that, The selective extraction method includes: A mixed lithium ore alkaline leaching solution is extracted with a composite extractant to obtain a loaded organic phase; the loaded organic phase is then eluted and back-extracted sequentially to obtain a back-extract; a precipitant is added to the back-extract, a precipitation reaction is carried out, and solid-liquid separation is performed to obtain a lithium carbonate product; The composite extractant includes an extractant and a diluent, wherein the extractant includes salicylate compounds and phosphate compounds.

2. The selective extraction method as described in claim 1, characterized in that, The salicylate esters include any one or a combination of at least two of the following: phenyl salicylate, isoamyl salicylate, isooctyl salicylate, benzyl salicylate, isodecanyl salicylate, or phenethyl salicylate. And / or, the phosphate ester compounds include any one or a combination of at least two of the following: tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, di(2-ethylhexyl)phenyl phosphate, or 2-ethylhexyl diphenyl phosphate; And / or, in the composite extractant, the molar ratio of salicylate esters to phosphate esters is (0.5~2):1; And / or, the diluent comprises any one of kerosene, sulfonated kerosene, liquid paraffin, D80, 260# solvent oil, Escaid 110, butyl benzoate, heptyl acetate, octanol, dodecyl alcohol, 4-methyl-2-pentanone, diisobutyl ketone, S150 or toluene, or a combination of at least two that are miscible in any volume ratio; And / or, in the composite extractant, the concentration of the extractant is 0.1 mol / L to 1 mol / L.

3. The selective extraction method as described in claim 1, characterized in that, The O / A ratio of the extracted material is (0.1~5):1; And / or, the extraction temperature is 20℃~60℃; And / or, the extraction time is 5 min to 60 min; And / or, the extraction is performed using stage 1 to stage 5 countercurrent extraction.

4. The selective extraction method as described in claim 1, characterized in that, The eluent used for elution includes any one or a combination of at least two of hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, oxalic acid, acetic acid, citric acid, and tartaric acid. And / or, the concentration of the eluent used in the elution is 0 mol / L to 1 mol / L.

5. The selective extraction method as described in claim 1, characterized in that, The elution O / A ratio is (1~20):1; And / or, the elution temperature is 20°C to 60°C; And / or, the elution time is 5 min to 60 min; And / or, the elution is performed using stage 1 to stage 5 countercurrent elution.

6. The selective extraction method as described in claim 1, characterized in that, The back-extraction agent used in the back-extraction includes any one or a combination of at least two of hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, oxalic acid, acetic acid, citric acid and tartaric acid. And / or, the concentration of the back-extraction agent used in the back-extraction is 1 mol / L to 5 mol / L.

7. The selective extraction method as described in claim 1, characterized in that, The O / A ratio of the back-extraction is (1~20):1; And / or, the back-extraction temperature is 20°C to 60°C; And / or, the back-extraction time is 5 min to 60 min; And / or, the back-extraction adopts 1-5 stage countercurrent back-extraction.

8. The selective extraction method as described in claim 1, characterized in that, The precipitant includes any one or a combination of at least two of sodium carbonate, ammonium carbonate, sodium bicarbonate or ammonium bicarbonate. And / or, the concentration of the precipitant added to the back-extraction solution is 0.1 mol / L to 2.5 mol / L.

9. The selective extraction method as described in claim 1, characterized in that, The precipitation reaction is carried out at a temperature of 80℃~100℃; And / or, the precipitation reaction time is 60 min to 120 min; And / or, the temperature for solid-liquid separation is 70℃~100℃.

10. The selective extraction method as described in claim 1, characterized in that, Na in the alkaline leaching solution of the lithium ore + K + and Li + Mass concentration meter, c(Na) + ):c(Li + )≤40, c(K) + ):c(Li + )≤20; And / or, the pH of the lithium ore alkali leaching solution is 10-14.

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