Lithium extraction method based on extraction-back extraction

Abstract

The invention relates to a lithium extraction method based on extraction-back extraction, which comprises the following steps: carrying out extraction and phase separation on a lithium-containing solution by using a composite extraction liquid to obtain a lithium-containing loaded oil phase, the composite extraction liquid comprises an extraction agent and a diluent, and the diluent is selected from 1, 2, 3-trimethyl-1, 3-pentanediol monoisobutyrate or 1, 2, 3-trimethyl-1, 3-pentanediol monoisobutyrate. The crown ether is at least one of 2, 3-dipropoxy crown ether, 15-crown ether-5, dibenzo-18-crown ether-6, calix [4] arene, calix [6] arene, calix [8] arene, tricyclodecenyl acetate, benzothiazole and 7-(4-ethyl-1-methyl octyl)-8-hydroxyquinoline; cO2 is introduced into the lithium-containing loaded oil phase to be mixed, a gas-liquid mixture is obtained, then the gas-liquid mixture is mixed with water to be subjected to reverse extraction and phase separation, and reverse extraction liquid is obtained; and carrying out heat treatment on the strip liquor to obtain lithium carbonate. According to the invention, CO2 is firstly introduced into the lithium-containing loaded oil phase for mixing, so that CO2 gas molecules can be effectively dispersed and adsorbed in pore channels, the utilization rate of CO2 is improved, the energy consumption can be effectively reduced, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium extraction, and particularly to a lithium extraction method based on extraction - back - extraction. Background Art

[0002] CN110240183A, CN110656239A, etc. have all disclosed using CO2 to replace traditional hydrochloric acid, etc. for back - extraction of lithium. Although the introduction methods of CO2 are different, essentially it is the H generated by introducing CO2 into water + exchanging with Li + for exchange.

[0003] Due to the low solubility of CO2 in water, at 25 °C and normal pressure, the solubility of CO2 in every 100 g of water is 0.144 g. When pressurized to 0.2 MPa, the solubility increases to 0.294 g. When pressurized to 0.4 MPa, the solubility increases to 0.583 g. When pressurized to 0.5 MPa, the solubility increases to 0.724 g. Although the solubility is relatively increased by pressurization, the overall dissolved amount is still small, and too high pressure will affect the use of equipment, increase the equipment pressure grade, and increase the equipment cost. Taking the treatment of a lithium - loaded oil phase with a lithium loading of 2.8 g / L in production as an example, when the flow rate of the lithium - loaded oil phase is 10 m 3 / h and the inlet pressure of CO2 is 0.5 MPa, 176 kg of CO2 is required to completely back - extract the lithium in the lithium - loaded oil phase, and 24 tons of water is required to completely dissolve it in water. In addition, when the three phases of CO2, the lithium - loaded oil phase, and water are mixed, too long mixing time will exacerbate the emulsification problem. Therefore, in order to shorten the mixing time and ensure the dissolved amount of CO2, the actual introduction amounts of water and CO2 are generally 2 times the theoretical values, that is, the hourly feed amount is 10 m 3 of the lithium - loaded oil phase, 48 tons of water, and 352 kg of CO2, resulting in relatively low overall production efficiency and large energy consumption. Summary of the Invention

[0004] Based on this, it is necessary to provide a lithium extraction method based on extraction - back - extraction for the above - mentioned problems, which can effectively reduce energy consumption and improve production efficiency.

[0005] A lithium extraction method based on extraction - back - extraction includes the following steps:

[0006] S1. Use a composite extractant to extract and phase-separate the lithium-containing solution to obtain a lithium-loaded oil phase. Among them, the composite extractant includes an extractant and a diluent, and the diluent is selected from at least one of 1,3-dipropoxy crown ether, 15-crown-5, dibenzo-18-crown-6, calix[4]arene, calix[6]arene, calix[8]arene, tricyclodecenyl acetate, 5-methyl-2-(1-methylethyl) cyclohexyl acetate, benzothiazole, 7-(4-ethyl-1-methyloctyl)-8-hydroxyquinoline;

[0007] S2. First, introduce CO2 into the lithium-loaded oil phase for mixing to obtain a gas-liquid mixture, and then mix the gas-liquid mixture with water for back-extraction and phase separation to obtain a back-extracted solution;

[0008] S3. Heat-treat the back-extracted solution to obtain lithium carbonate.

[0009] In one embodiment, the extractant is selected from at least one of trioxythiophene oxide, 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione, 1,1,1,2,2-pentafluoro-6,6-dimethyl-3,5-heptanedione, 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione, benzoyltrifluoroacetone, 1-phenyl-1,3-butadione, 1-benzoyl-2-nonanone, trialkyl phosphate, trialkyl phosphine oxide, trioctyl phosphine oxide, trihexyl phosphine oxide, dialkyl phosphate, methyl isobutyl ketone, 1-phenylazo-2-naphthol, n-octanol, isooctanol, 2-ethylhexanol, 14-crown-4 ether dibutyl butylphosphonate, dibutyl butylphosphate, methylene tetrabutyl bisphosphonate, trioctylamine oxide, 1,10-phenanthroline, quaternary ammonium salt N 263 , dimethyldi(N-octadecyl) ammonium chloride, methyl dioctyl sulfonium chloride, 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide.

[0010] In one embodiment, the extractant includes a first extractant and a second extractant. Among them, the first extractant is selected from at least one of trithiophene oxide, 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione, 1,1,1,2,2-pentafluoro-6,6-dimethyl-3,5-heptanedione, 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione, benzoyltrifluoroacetone, 1-phenyl-1,3-butanedione, and 1-benzoyl-2-nonanone. The second extractant is selected from at least one of trialkyl phosphate, trialkyl phosphine oxide, trioctyl phosphine oxide, trihexyl phosphine oxide, dialkyl phosphate, methyl isobutyl ketone, 1-phenylazo-2-naphthol, n-octanol, isooctanol, 2-ethylhexanol, 14-crown-4 ether dibutyl butylphosphonate, dibutyl butyl phosphate, methylene tetrabutyl bisphosphate, trioctylamine oxide, 1,10-phenanthroline, and quaternary ammonium salt N 263 , at least one of dimethyldi(N-octadecyl)ammonium chloride, methyl dioctyl sulfonium chloride, and 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.

[0011] In one embodiment, the volume ratio of the first extractant to the second extractant is 1:2 - 2:1.

[0012] In one embodiment, the volume fraction of the diluent in the composite extract is 40% - 60%.

[0013] In one embodiment, in the step of introducing CO2 into the lithium-loaded oil phase for mixing, the introduction pressure of CO2 is 0.2 MPa - 0.5 MPa.

[0014] In one embodiment, in the step of introducing CO2 into the lithium-loaded oil phase for mixing, the mixing temperature is 20°C - 30°C, and the mixing time is 1 min - 3 min.

[0015] In one embodiment, in the step of mixing the gas-liquid mixture with water for back extraction, the mixing temperature is 20°C - 30°C, and the mixing time is 2 min - 4 min.

[0016] In one embodiment, step S2 also obtains an empty composite extract, and the empty composite extract is recycled to step S1 for use.

[0017] In one embodiment, step S3 also obtains a mother liquor for lithium precipitation and CO2. The CO2 is recycled to step S2 for use, and the mother liquor for lithium precipitation is recycled to step S1 and / or step S2 for use.

[0018] In the method of the present invention, the diluent used does not affect the original lithium extraction performance of the extractant. At the same time, the composite extraction liquid obtained by compounding with the extractant has pore channel fluidity and can adsorb and capture CO2. Therefore, in the present invention, CO2 is first introduced into the lithium-loaded oil phase for mixing, which can effectively disperse and adsorb CO2 gas molecules in the pores, improve the utilization rate of CO2, and thus effectively reduce energy consumption and improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 It is a process flow schematic diagram of the lithium extraction method based on extraction and back-extraction of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] To facilitate the understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the description of the present invention in this specification are only for the purpose of describing specific embodiments or examples and are not intended to limit the present invention. The optional range of the term "and / or" used herein includes any one of two or more related listed items, as well as any and all combinations of the related listed items. The any and all combinations include any two related listed items, any more related listed items, or all related listed items.

[0023] In the present invention, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0024] Such asFigure 1 As shown in Figure 1 , the lithium extraction method based on extraction - back - extraction provided by the present invention includes the following steps:

[0025] S1. Using a composite extraction solution to extract and phase - separate a lithium - containing solution to obtain a lithium - loaded oil phase. Among them, the composite extraction solution includes an extractant and a diluent, and the diluent is selected from at least one of 1,3 - dipropoxy crown ether, 15 - crown - 5, dibenzo - 18 - crown - 6, calix[4]arene, calix[6]arene, calix[8]arene, tricyclodecenyl acetate, 5 - methyl - 2 - (1 - methylethyl) cyclohexyl acetate, benzothiazole, 7 - (4 - ethyl - 1 - methyloctyl) - 8 - hydroxyquinoline;

[0026] S2. First, introducing CO2 into the lithium - loaded oil phase for mixing to obtain a gas - liquid mixture, and then mixing the gas - liquid mixture with water for back - extraction and phase - separation to obtain a back - extraction solution;

[0027] S3. Heat - treating the back - extraction solution to obtain lithium carbonate.

[0028] The present invention has no special requirements for the lithium - containing solution in step S1. The lithium - containing solution is selected from salt lake brine, lithium ore leaching solution, lithium battery waste leaching solution, or mother liquor of lithium precipitation, etc. Among them, the lithium - containing solution is an alkaline lithium - containing solution, and further preferably a lithium - containing solution with a pH of 10 - 13.

[0029] The composite extraction solution adopted by the present invention includes an extractant and a diluent. Compared with the existing composite extraction solution, mainly the diluents such as kerosene and alkanes are replaced with at least one of 1,3 - dipropoxy crown ether, 15 - crown - 5, dibenzo - 18 - crown - 6, calix[4]arene, calix[6]arene, calix[8]arene, tricyclodecenyl acetate, 5 - methyl - 2 - (1 - methylethyl) cyclohexyl acetate, benzothiazole, 7 - (4 - ethyl - 1 - methyloctyl) - 8 - hydroxyquinoline. On the one hand, these diluents will not affect the original lithium - extraction performance of the extractant, and at the same time, the composite extraction solution obtained by compounding with the extractant has pore channel fluidity and can adsorb and capture CO2.

[0030] Optionally, the extractant is a self-hydrophobic compound, preferably selected from trithiophene oxide, 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione, 1,1,1,2,2-pentafluoro-6,6-dimethyl-3,5-heptanedione, 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione, benzoyltrifluoroacetone, 1-phenyl-1,3-butanedione, 1-benzoyl-2-nonanone, trialkyl phosphate, trialkyl phosphine oxide, trioctyl phosphine oxide, trihexyl phosphine oxide, dialkyl phosphate, methyl isobutyl ketone, 1-phenylazo-2-naphthol, n-octanol, isooctanol, 2-ethylhexanol, 14-crown-4 ether dibutyl butylphosphonate, dibutyl butylphosphate, methylenetetrabutyl bisphosphonate, trioctylamine oxide, 1,10-phenanthroline, quaternary ammonium salt N 263 and at least one of dimethyldi(N-octadecyl)ammonium chloride, methyl dioctyl sulfonium chloride, 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. Among them, the trialkyl phosphate includes tributyl phosphate, etc.

[0031] To better improve the extraction effect and better generate pore fluidity and adsorb and capture CO2 after compounding, preferably, the extractant includes a first extractant and a second extractant. Among them, the first extractant is selected from at least one of trithiophene oxide, 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione, 1,1,1,2,2-pentafluoro-6,6-dimethyl-3,5-heptanedione, 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione, benzoyltrifluoroacetone, 1-phenyl-1,3-butanedione, 1-benzoyl-2-nonanone, and the second extractant is selected from trialkyl phosphate, trialkyl phosphine oxide, trioctyl phosphine oxide, trihexyl phosphine oxide, dialkyl phosphate, methyl isobutyl ketone, 1-phenylazo-2-naphthol, n-octanol, isooctanol, 2-ethylhexanol, 14-crown-4 ether dibutyl butylphosphonate, dibutyl butylphosphate, methylenetetrabutyl bisphosphonate, trioctylamine oxide, 1,10-phenanthroline, quaternary ammonium salt N 263 and at least one of dimethyldi(N-octadecyl)ammonium chloride, methyl dioctyl sulfonium chloride, 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. Further, the volume ratio of the first extractant to the second extractant is preferably 1:2 - 2:1.

[0032] Optionally, the volume ratio of the extractant to the diluent in the composite extractant is not limited and is specifically adjusted according to the selection of the extractant and the diluent. Preferably, the volume fraction of the diluent in the composite extractant is 40% - 60%, which can not only ensure the extraction efficiency of the composite extractant but also ensure the adsorption amount of CO2 by the composite extractant.

[0033] Furthermore, after using the composite extractant to extract and phase-separate the lithium-containing solution to obtain the lithium-loaded oil phase, in step S2, first introducing CO2 into the lithium-loaded oil phase for mixing can effectively disperse and adsorb CO2 gas molecules in the pores of the lithium-loaded oil phase to obtain a gas-liquid mixture, and then mixing the gas-liquid mixture with water and reacting to generate H + ,H + Then exchange with Li + to achieve back-extraction.

[0034] Optionally, in the step of introducing CO2 into the lithium-loaded oil phase for mixing, the introduction pressure of CO2 is preferably 0.2 MPa - 0.5 MPa, and more preferably 0.2 MPa - 0.4 MPa, which helps to improve the reaction efficiency.

[0035] Temperature affects the solubility of CO2 in water. The lower the temperature, the higher the solubility. However, the lower the temperature, the more it will affect the back-extraction efficiency. Optionally, in the step of introducing CO2 into the lithium-loaded oil phase for mixing, the mixing temperature is preferably 20°C - 30°C, and in the step of mixing the gas-liquid mixture with water for back-extraction, the mixing temperature is also preferably 20°C - 30°C, and the overall effect is better.

[0036] Optionally, in the step of introducing CO2 into the lithium-loaded oil phase for mixing, the mixing time is preferably 1 min - 3 min, and in the step of mixing the gas-liquid mixture with water for back-extraction, the mixing time is preferably 2 min - 4 min, which can ensure that CO2 can be fully adsorbed in the lithium-loaded oil phase, and when mixing with water, it can ensure the back-extraction efficiency and avoid emulsification.

[0037] It can be understood that after phase separation in step S2, an empty composite extractant is also obtained, and the empty composite extractant is recycled to step S1 for use in mixing with the lithium-containing solution for extraction to prepare the lithium-loaded oil phase.

[0038] In step S3, the temperature of the heat treatment is preferably greater than or equal to 50°C. Considering efficiency and yield, the temperature of the heat treatment is further preferably 70°C - 100°C.

[0039] It can be understood that after heat-treating the back-extraction liquid in step S3, a lithium precipitation mother liquor and CO2 are also obtained. Preferably, CO2 is recycled to step S2 for mixing with the lithium-loaded oil phase for recycling for back-extraction, and the lithium precipitation mother liquor can be recycled to step S2 for mixing with the gas-liquid mixture for back-extraction, or the lithium precipitation mother liquor can be recycled to step S1 for mixing with the lithium-containing solution for extraction.

[0040] In summary, the composite extraction liquid obtained by compounding the diluent and the extractant used in the present invention has pore fluidity and can adsorb and capture CO2. Therefore, in the present invention, CO2 is first introduced into the lithium-loaded oil phase for mixing, which can effectively disperse and adsorb CO2 gas molecules in the pores, improving the utilization rate of CO2. Specifically, when the temperature is preferably 20°C - 30°C, the pressure is preferably 0.2 MPa - 0.5 MPa, and when the volume fraction of the diluent in the composite extraction liquid is 40% - 60%, the adsorption amount of CO2 in the composite extraction liquid can reach 20 g / L - 24 g / L. During actual production, the feeding amount of CO2 only needs to be 1.13 times - 1.36 times of the theoretical amount, and the feeding amount of water only needs 3.4 m 3 / h - 4 m 3 / h, thus effectively reducing energy consumption.

[0041] In addition, during actual production, the lithium content in the stripping liquid needs to reach 7 g / L - 8 g / L, that is, close to the saturation solubility (8.4 g / L), to carry out heat treatment to prepare lithium carbonate, so as to maximize the yield of lithium carbonate in one pyrolysis on the premise of ensuring no crystallization. In the prior art, due to the high feeding amount of water and the small oil-water ratio (close to 1:5), the lithium content extracted into pure water is low. In actual production, the stripping liquid needs to be continuously pumped to the front end of stripping to mix and recycle with the lithium-loaded oil phase instead of pure water to increase its lithium concentration. However, in the present invention, due to the reduction of the water usage, the lithium concentration in the stripping liquid is relatively high, and the lithium concentration in the stripping liquid can reach 7 g / L - 8 g / L after one stripping, effectively improving the production efficiency.

[0042] Hereinafter, the lithium extraction method based on extraction-stripping will be further described through the following specific examples.

[0043] Example 1

[0044] 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione and 2-ethylhexanol are used as extractants, and 1,3-dipropoxy crown ether is used as a diluent to obtain a composite extraction liquid by mixing. The volume fraction of 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione in the composite extraction liquid is controlled to be 20%, the volume fraction of 2-ethylhexanol is 20%, and the volume fraction of 1,3-dipropoxy crown ether is 60%. The pH of the salt lake brine with a lithium concentration of 1.1 g / L is adjusted to 12, and then it is mixed with the composite extraction liquid for extraction. The volume ratio of the composite extraction liquid to the salt lake brine is controlled to be 1:2.5. After phase separation, a lithium-loaded oil phase with a lithium concentration of 2.72 g / L is obtained, and the lithium extraction rate is 99.01%.

[0045] Control the flow rate of the above-mentioned lithium-loaded oil phase to be 10 m 3 / h (calculated under the conditions of 25°C and 0.2 MPa, theoretically 171 kg of CO2 and 58.4 m 3 / h of water), first introduce 195 kg of CO2 into the lithium-containing loaded oil phase to obtain a gas-liquid mixture. Among them, the pressure of CO2 introduction is 0.2 MPa, the mixing time is 1 min, and the mixing temperature is 25°C. Then mix the gas-liquid mixture with water for back-extraction and phase separation. The mixing time is 2 min, and the mixing temperature is 25°C to obtain a back-extraction solution with a lithium concentration of 7.1 g / L and an empty composite extraction solution. Among them, the flow rate of water is 3.7 m 3 / h, and the empty composite extraction solution is recycled to the extraction section.

[0046] Then heat the back-extraction solution to 80°C to obtain lithium carbonate products, mother liquor for lithium precipitation, and CO2. Among them, the mother liquor for lithium precipitation is recycled to the extraction section, and CO2 is recycled to the back-extraction section.

[0047] In this example, the usage amount of CO2 is only 1.14 times the theoretical value, and the usage amount of water is only 6.3% of the theoretical value. If the traditional process using kerosene as a diluent is adopted, 342 kg of CO2 and 116.8 m 3 / h of water are required. Compared with this, the energy consumption is effectively reduced, and a back-extraction solution with a lithium concentration of 7.1 g / L can be obtained by one extraction, effectively improving the production efficiency.

[0048] Example 2

[0049] Use 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione and isooctanol as extractants, and 15-crown-5 as a diluent, and mix to obtain a composite extraction solution. Control the volume fraction of 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione in the composite extraction solution to be 20%, the volume fraction of isooctanol to be 20%, and the volume fraction of 15-crown-5 to be 60%. Adjust the pH of the salt lake brine with a lithium concentration of 1.1 g / L to 12, and then mix it with the composite extraction solution for extraction. Control the volume ratio of the composite extraction solution to the salt lake brine to be 1:2.5. After phase separation, a lithium-containing loaded oil phase with a lithium concentration of 2.73 g / L is obtained, and the lithium extraction rate is 99.19%.

[0050] Control the flow rate of the above-mentioned lithium-containing loaded oil phase to be 10 m 3 / h (calculated under the conditions of 25°C and 0.2 MPa, theoretically 171.6 kg of CO2 and 58.6 m 3 / h of water), first, 206 kg of CO2 is introduced into the lithium-loaded oil phase to obtain a gas-liquid mixture. Among them, the CO2 introduction pressure is 0.2 MPa, the mixing time is 1.5 min, and the mixing temperature is 25 °C. Then, the gas-liquid mixture is mixed with water for back-extraction and phase separation. The mixing time is 2.5 min, and the mixing temperature is 25 °C, obtaining a back-extraction solution with a lithium concentration of 7.21 g / L and an empty composite extraction solution. Among them, the flow rate of water is 3.72 m 3 / h, and the empty composite extraction solution is recycled to the extraction section.

[0051] Then, the back-extraction solution is heated to 80 °C to obtain lithium carbonate products, mother liquor for lithium precipitation, and CO2. Among them, the mother liquor for lithium precipitation is recycled to the extraction section, and CO2 is recycled to the back-extraction section.

[0052] In this example, the usage amount of CO2 is only 1.20 times the theoretical value, and the usage amount of water is only 6.3% of the theoretical value. If the traditional process using kerosene as a diluent is adopted, 342 kg of CO2 and 117.2 m 3 / h of water are required. Compared with this, the energy consumption is effectively reduced, and a back-extraction solution with a lithium concentration of 7.21 g / L can be obtained by one extraction, effectively improving the production efficiency.

[0053] Example 3

[0054] Using 1-phenyl-1,3-butanedione and dialkyl phosphate as extractants, and dibenzo-18-crown-6 as a diluent, a composite extraction solution is obtained by mixing. The volume fraction of 1-phenyl-1,3-butanedione in the composite extraction solution is controlled to be 27%, the volume fraction of dialkyl phosphate is 13%, and the volume fraction of dibenzo-18-crown-6 is 60%. The pH of the salt lake brine with a lithium concentration of 1.1 g / L is adjusted to 12, and then it is mixed with the composite extraction solution for extraction. The volume ratio of the composite extraction solution to the salt lake brine is controlled to be 1:2.5. After phase separation, a lithium-loaded oil phase with a lithium concentration of 2.732 g / L is obtained, and the lithium extraction rate is 99.36%.

[0055] Controlling the flow rate of the above-mentioned lithium-loaded oil phase to be 10 m 3 / h (calculated under the conditions of 25 °C and 0.2 MPa, theoretically 171.8 kg of CO2 and 58.65 m 3 / h of water are required), first, 223 kg of CO2 is introduced into the lithium-loaded oil phase to obtain a gas-liquid mixture. Among them, the CO2 introduction pressure is 0.2 MPa, the mixing time is 2 min, and the mixing temperature is 25 °C. Then, the gas-liquid mixture is mixed with water for back-extraction and phase separation. The mixing time is 3 min, and the mixing temperature is 25 °C, obtaining a back-extraction solution with a lithium concentration of 7.45 g / L and an empty composite extraction solution. Among them, the flow rate of water is 3.64 m 3 / h, the empty composite extractant is recycled for the extraction section.

[0056] Then, the stripping solution is heated to 80 °C to obtain lithium carbonate product, mother liquor for lithium precipitation and CO2. Among them, the mother liquor for lithium precipitation is recycled to the extraction section, and CO2 is recycled to the stripping section.

[0057] In this example, the usage amount of CO2 is only 1.30 times of the theoretical value, and the usage amount of water is only 6.2% of the theoretical value. Compared with the traditional process using kerosene as the diluent, which requires 343.6 kg of CO2 and 117.3 m 3 / h of water, the energy consumption is effectively reduced, and the stripping solution with a lithium concentration of 7.45 g / L can be obtained by one extraction, effectively improving the production efficiency.

[0058] Example 4

[0059] Benzoyltrifluoroacetone, 1-benzoyl-2-nonanone and dibutyl phosphate are used as extractants, and calix[4]arene is used as the diluent. They are mixed to obtain a composite extractant. The volume fractions of benzoyltrifluoroacetone and 1-benzoyl-2-nonanone in the composite extractant are controlled to be 15% respectively, the volume fraction of dibutyl phosphate is 15%, and the volume fraction of calix[4]arene is 55%. The pH of the salt lake brine with a lithium concentration of 1.1 g / L is adjusted to 12, and then it is mixed with the composite extractant for extraction. The volume ratio of the composite extractant to the salt lake brine is controlled to be 1:2.5. After phase separation, a lithium-loaded oil phase with a lithium concentration of 2.741 g / L is obtained, and the lithium extraction rate is 99.68%.

[0060] Control the flow rate of the above-mentioned lithium-loaded oil phase to be 10 m 3 / h (calculated under the conditions of 25 °C and 0.3 MPa, theoretically 172.3 kg of CO2 and 39.2 m 3 / h of water are required). First, 234 kg of CO2 is introduced into the lithium-loaded oil phase to obtain a gas-liquid mixture. Among them, the introduction pressure of CO2 is 0.3 MPa, the mixing time is 2 min, and the mixing temperature is 25 °C. Then, the gas-liquid mixture is mixed with water for stripping and phase separation. The mixing time is 3 min, and the mixing temperature is 25 °C. A stripping solution with a lithium concentration of 7.79 g / L and an empty composite extractant are obtained. Among them, the flow rate of water is 3.5 m 3 / h, and the empty composite extractant is recycled for the extraction section.

[0061] Then, the stripping solution is heated to 80 °C to obtain lithium carbonate product, mother liquor for lithium precipitation and CO2. Among them, the mother liquor for lithium precipitation is recycled to the extraction section, and CO2 is recycled to the stripping section.

[0062] In this embodiment, the usage amount of CO2 is only 1.36 times of the theoretical value, and the usage amount of water is only 8.9% of the theoretical value. Compared with the traditional process using kerosene as the diluent, which requires 344.6 kg of CO2 and 78.4 m 3 / h of water, the energy consumption is effectively reduced, and a stripping solution with a lithium concentration of 7.79 g / L can be obtained by one extraction, effectively improving the production efficiency.

[0063] Example 5

[0064] Using 1,1,1,2,2-pentafluoro-6,6-dimethyl-3,5-heptanedione and methyl isobutyl ketone as extractants and calix[6]arene as the diluent, a composite extractant solution is obtained by mixing. Control the volume fraction of 1,1,1,2,2-pentafluoro-6,6-dimethyl-3,5-heptanedione in the composite extractant solution to be 20%, the volume fraction of methyl isobutyl ketone to be 30%, and the volume fraction of calix[6]arene to be 50%. Adjust the pH of the salt lake brine with a lithium concentration of 1.1 g / L to 12, and then mix it with the composite extractant solution for extraction. Control the volume ratio of the composite extractant solution to the salt lake brine to be 1:2.5. After phase separation, a lithium-loaded oil phase with a lithium concentration of 2.736 g / L is obtained, and the lithium extraction rate is 99.50%.

[0065] Control the flow rate of the above lithium-loaded oil phase to be 10 m 3 / h (calculated under the conditions of 25 °C and 0.3 MPa, theoretically 172 kg of CO2 and 44.72 m 3 / h of water are required). First, 223.6 kg of CO2 is introduced into the lithium-loaded oil phase to obtain a gas-liquid mixture. Among them, the CO2 introduction pressure is 0.3 MPa, the mixing time is 2 min, and the mixing temperature is 30 °C. Then, the gas-liquid mixture is mixed with water for stripping and phase separation. The mixing time is 3 min, and the mixing temperature is 30 °C. A stripping solution with a lithium concentration of 7.65 g / L and an empty composite extractant solution are obtained. Among them, the flow rate of water is 3.55 m 3 / h, and the empty composite extractant solution is recycled to the extraction section.

[0066] Then, the stripping solution is heated to 80 °C to obtain lithium carbonate products, lithium precipitation mother liquor, and CO2. Among them, the lithium precipitation mother liquor is recycled to the extraction section, and CO2 is recycled to the stripping section.

[0067] In this embodiment, the usage amount of CO2 is only 1.30 times of the theoretical value, and the usage amount of water is only 7.9% of the theoretical value. Compared with the traditional process using kerosene as the diluent, which requires 344 kg of CO2 and 89.44 m 3 / h of water, the energy consumption is effectively reduced, and a stripping solution with a lithium concentration of 7.65 g / L can be obtained by one extraction, effectively improving the production efficiency.

[0068] Example 6

[0069] Using 1,1,1,2,2-pentafluoro-6,6-dimethyl-3,5-heptanedione, 1,10-phenanthroline, and quaternary ammonium salt N 263 as the extractant, calix[8]arene as the diluent, and mixing to obtain a composite extractant solution. Control the volume fraction of 1,1,1,2,2-pentafluoro-6,6-dimethyl-3,5-heptanedione in the composite extractant solution to be 20%, the volume fraction of 1,10-phenanthroline to be 10%, and the volume fraction of quaternary ammonium salt N 263 to be 30%, and the volume fraction of calix[8]arene to be 40%. Adjust the pH of the salt lake brine with a lithium concentration of 1.1 g / L to 12, and then mix it with the composite extractant solution for extraction. Control the volume ratio of the composite extractant solution to the salt lake brine to be 1:2.5. After phase separation, obtain a lithium-loaded oil phase with a lithium concentration of 2.722 g / L, and the lithium extraction rate is 99.00%.

[0070] Control the flow rate of the above lithium-loaded oil phase to be 10 m 3 / h (calculated under the conditions of 25°C and 0.3 MPa, theoretically 171 kg of CO2 and 44.45 m 3 / h of water are required). First, introduce 214 kg of CO2 into the lithium-loaded oil phase to obtain a gas-liquid mixture. Among them, the CO2 introduction pressure is 0.3 MPa, the mixing time is 3 min, and the mixing temperature is 30°C. Then mix the gas-liquid mixture with water for back-extraction and phase separation. The mixing time is 4 min, and the mixing temperature is 30°C. Obtain a back-extraction solution with a lithium concentration of 7.70 g / L and an empty composite extractant solution. Among them, the flow rate of water is 3.52 m 3 / h, and the empty composite extractant solution is recycled to the extraction section.

[0071] Then heat the back-extraction solution to 80°C to obtain lithium carbonate products, lithium precipitation mother liquor, and CO2. Among them, the lithium precipitation mother liquor is recycled to the extraction section, and CO2 is recycled to the back-extraction section.

[0072] In this example, the usage amount of CO2 is only 1.25 times the theoretical value, and the usage amount of water is only 7.9% of the theoretical value. Compared with the traditional process using kerosene as the diluent, which requires 342 kg of CO2 and 88.9 m 3 / h of water, the energy consumption is effectively reduced, and a back-extraction solution with a lithium concentration of 7.7 g / L can be obtained in one extraction, effectively improving the production efficiency.

[0073] Example 7

[0074] Using benzoyltrifluoroacetone and 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide as extractants and tricyclodecenyl acetate as a diluent, a composite extraction solution is obtained by mixing. The volume fraction of benzoyltrifluoroacetone in the composite extraction solution is controlled to be 30%, the volume fraction of 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide is 30%, and the volume fraction of tricyclodecenyl acetate is 40%. The pH of the salt lake brine with a lithium concentration of 1.1 g / L is adjusted to 12, and then it is mixed with the composite extraction solution for extraction. The volume ratio of the composite extraction solution to the salt lake brine is controlled to be 1:2.5. After phase separation, a lithium-loaded oil phase with a lithium concentration of 2.747 g / L is obtained, and the lithium extraction rate is 99.91%.

[0075] Control the flow rate of the above lithium-loaded oil phase to be 10 m 3 / h (calculated under the conditions of 25 °C and 0.4 MPa, theoretically 172.7 kg of CO2 and 33.80 m 3 / h of water are required). First, 215 kg of CO2 is introduced into the lithium-loaded oil phase to obtain a gas-liquid mixture. Among them, the CO2 introduction pressure is 0.4 MPa, the mixing time is 3 min, and the mixing temperature is 30 °C. Then the gas-liquid mixture is mixed with water for back extraction and phase separation. The mixing time is 4 min, and the mixing temperature is 30 °C. A back extraction solution with a lithium concentration of 7.84 g / L and an empty composite extraction solution are obtained. Among them, the flow rate of water is 3.48 m 3 / h, and the empty composite extraction solution is recycled to the extraction section.

[0076] Then the back extraction solution is heated to 80 °C to obtain lithium carbonate products, mother liquor for lithium precipitation, and CO2. Among them, the mother liquor for lithium precipitation is recycled to the extraction section, and CO2 is recycled to the back extraction section.

[0077] In this example, the usage amount of CO2 is only 1.24 times the theoretical value, and the usage amount of water is only 10.3% of the theoretical value. Compared with the traditional process using kerosene as a diluent, which requires 345.4 kg of CO2 and 67.6 m 3 / h of water, the energy consumption is effectively reduced, and a back extraction solution with a lithium concentration of 7.84 g / L can be obtained in one extraction, effectively improving the production efficiency.

[0078] Example 8

[0079] Benzoyltrifluoroacetone, 1-phenyl-1,3-butanedione, dimethyldi(N-octadecyl)ammonium chloride and methyldioctylsulfonium chloride are used as extractants, and 5-methyl-2-(1-methylethyl)cyclohexyl acetate is used as a diluent. They are mixed to obtain a composite extractant solution. The volume fractions of benzoyltrifluoroacetone, 1-phenyl-1,3-butanedione, dimethyldi(N-octadecyl)ammonium chloride, and methyldioctylsulfonium chloride in the composite extractant solution are controlled to be 10% respectively, and the volume fraction of 5-methyl-2-(1-methylethyl)cyclohexyl acetate is 60%. The pH of the salt lake brine with a lithium concentration of 1.1 g / L is adjusted to 12, and then it is mixed with the composite extractant solution for extraction. The volume ratio of the composite extractant solution to the salt lake brine is controlled to be 1:2.5. After phase separation, a lithium-loaded oil phase with a lithium concentration of 2.738 g / L is obtained, and the lithium extraction rate is 99.57%.

[0080] Control the flow rate of the above lithium-loaded oil phase to be 10 m 3 / h (calculated under the conditions of 25 °C and 0.4 MPa, theoretically 172.2 kg of CO2 and 29.54 m 3 / h of water are required). First, 215 kg of CO2 is introduced into the lithium-loaded oil phase to obtain a gas-liquid mixture. Among them, the CO2 introduction pressure is 0.4 MPa, the mixing time is 3 min, and the mixing temperature is 25 °C. Then, the gas-liquid mixture is mixed with water for back-extraction and phase separation. The mixing time is 4 min, and the mixing temperature is 25 °C. A back-extracted solution with a lithium concentration of 7.89 g / L and an empty composite extractant solution are obtained. Among them, the flow rate of water is 3.46 m 3 / h, and the empty composite extractant solution is recycled to the extraction section.

[0081] Then, the back-extracted solution is heated to 80 °C to obtain lithium carbonate products, lithium precipitation mother liquor, and CO2. Among them, the lithium precipitation mother liquor is recycled to the extraction section, and CO2 is recycled to the back-extraction section.

[0082] In this example, the usage amount of CO2 is only 1.25 times of the theoretical value, and the usage amount of water is only 11.7% of the theoretical value. Compared with the traditional process using kerosene as a diluent, which requires 344.4 kg of CO2 and 59.08 m 3 / h of water, the energy consumption is effectively reduced, and a back-extracted solution with a lithium concentration of 7.89 g / L can be obtained by one extraction, effectively improving the production efficiency.

[0083] Example 9

[0084] Using 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione, benzoyltrifluoroacetone, trialkylphosphine oxide and trioctylphosphine oxide as extractants, and benzothiazole as a diluent, a composite extraction solution is obtained by mixing. The volume fractions of 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione, benzoyltrifluoroacetone, trialkylphosphine oxide and trioctylphosphine oxide in the composite extraction solution are controlled to be 10% respectively, and the volume fraction of benzothiazole is 60%. The pH of the salt lake brine with a lithium concentration of 1.1 g / L is adjusted to 12, and then it is mixed with the composite extraction solution for extraction. The volume ratio of the composite extraction solution to the salt lake brine is controlled to be 1:2.5. After phase separation, a lithium-loaded oil phase with a lithium concentration of 2.741 g / L is obtained, and the lithium extraction rate is 99.69%.

[0085] Control the flow rate of the above lithium-loaded oil phase to be 10 m 3 / h (calculated under the conditions of 25 °C and 0.4 MPa, theoretically 172.4 kg of CO2 and 25.72 m 3 / h of water are required). First, 215 kg of CO2 is introduced into the lithium-loaded oil phase to obtain a gas-liquid mixture. Among them, the CO2 introduction pressure is 0.4 MPa, the mixing time is 3 min, and the mixing temperature is 20 °C. Then the gas-liquid mixture is mixed with water for back extraction and phase separation. The mixing time is 4 min, and the mixing temperature is 20 °C. A back extraction solution with a lithium concentration of 7.96 g / L and an empty composite extraction solution are obtained. Among them, the flow rate of water is 3.44 m 3 / h, and the empty composite extraction solution is recycled to the extraction section.

[0086] Then the back extraction solution is heated to 80 °C to obtain lithium carbonate products, lithium precipitation mother liquor and CO2. Among them, the lithium precipitation mother liquor is recycled to the extraction section, and CO2 is recycled to the back extraction section.

[0087] In this example, the usage amount of CO2 is only 1.25 times of the theoretical value, and the usage amount of water is only 13.4% of the theoretical value. Compared with the traditional process using kerosene as a diluent, which requires 342 kg of CO2 and 116.8 m 3 / h of water, the energy consumption is effectively reduced, and a back extraction solution with a lithium concentration of 7.96 g / L can be obtained by one extraction, effectively improving the production efficiency.

[0088] Example 10

[0089] Using 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione, 1-phenyl-1,3-butanedione and 1-phenylazo-2-naphthol as extractants, and 7-(4-ethyl-1-methyloctyl)-8-hydroxyquinoline as a diluent, a composite extraction solution is obtained by mixing. The volume fractions of 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione and 1-phenyl-1,3-butanedione in the composite extraction solution are controlled to be 12.5% respectively, the volume fraction of 1-phenylazo-2-naphthol is 25%, and the volume fraction of 7-(4-ethyl-1-methyloctyl)-8-hydroxyquinoline is 50%. The pH of the salt lake brine with a lithium concentration of 1.1 g / L is adjusted to 12, and then it is mixed with the composite extraction solution for extraction. The volume ratio of the composite extraction solution to the salt lake brine is controlled to be 1:2.5. After phase separation, a lithium-loaded oil phase with a lithium concentration of 2.735 g / L is obtained, and the lithium extraction rate is 99.48%.

[0090] Control the flow rate of the above-mentioned lithium-loaded oil phase to be 10 m 3 / h (calculated under the conditions of 25 °C and 0.2 MPa, theoretically 172 kg of CO2 and 25.66 m 3 / h of water are required). First, 215 kg of CO2 is introduced into the lithium-loaded oil phase to obtain a gas-liquid mixture. Among them, the pressure of CO2 introduction is 0.4 MPa, the mixing time is 2 min, and the mixing temperature is 20 °C. Then, the gas-liquid mixture is mixed with water for back extraction and phase separation. The mixing time is 3 min, and the mixing temperature is 20 °C. A back extraction solution with a lithium concentration of 7.78 g / L and an empty composite extraction solution are obtained. Among them, the flow rate of water is 3.5 m 3 / h, and the empty composite extraction solution is recycled to the extraction section.

[0091] Then, the back extraction solution is heated to 80 °C to obtain lithium carbonate products, mother liquor for lithium precipitation and CO2. Among them, the mother liquor for lithium precipitation is recycled to the extraction section, and CO2 is recycled to the back extraction section.

[0092] In this example, the usage amount of CO2 is only 1.25 times of the theoretical value, and the usage amount of water is only 13.6% of the theoretical value. Compared with the traditional process using kerosene as a diluent, which requires 344 kg of CO2 and 51.32 m 3 / h of water, the energy consumption is effectively reduced, and a back extraction solution with a lithium concentration of 7.78 g / L can be obtained by one extraction, effectively improving the production efficiency.

[0093] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0094] The embodiments described above merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A lithium extraction method based on extraction-strip extraction, characterized in that: The following steps are involved: S1, extracting and phase-separating the lithium-containing solution with a composite extractant to obtain a lithium-loaded oil phase, wherein the composite extractant comprises an extractant and a diluent, and the diluent is selected from at least one of 1,3-dipropoxy crown ether, 15-crown ether-5, dibenzo-18-crown ether-6, calix[4]arene, calix[6]arene, calix[8]arene, tricyclodecenyl acetate, 5-methyl-2-(1-methylethyl)cyclohexyl acetate, benzothiazole, and 7-(4-ethyl-1-methyloctyl)-8-hydroxyquinoline; S2, firstly passing CO2 into the lithium-loaded oil phase for mixing to obtain a gas-liquid mixture, and then mixing the gas-liquid mixture with water for stripping and phase separation to obtain a stripping solution; S3, heat-treating the stripping solution to obtain lithium carbonate.

2. The lithium extraction method based on extraction-strip extraction according to claim 1, characterized in that: The extractant is selected from trioxythiophene oxide, 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione, 1,1,1,2,2-pentafluoro-6,6-dimethyl-3,5-heptanedione, 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione, benzoyltrifluoroacetone, 1-phenyl-1,3-butanedione, 1-benzoyl-2-nonanone, trialkyl phosphate, trialkyl phosphine oxide, trioctyl phosphine oxide, trihexyl phosphine oxide, dialkyl phosphate, methyl isobutyl ketone, 1-phenylazo-2-naphthol, n-octanol, isooctyl alcohol, 2-ethylhexanol, 14-crown-4 ether dibutyl butylphosphonate, dibutyl butyl phosphate, tetrabutyl methylene diphosphate, trioctylamine oxide, 1,10-phenanthroline, quaternary ammonium salt N 263 , dimethyldi(N-octadecyl)ammonium chloride, methyl dioctylsulfonium chloride, and 1-hydroxyethyl-3-methylimidazole bis(trifluoromethylsulfonyl)imide.

3. The lithium extraction method based on extraction-strip extraction according to claim 2, characterized in that: The extractant comprises a first extractant and a second extractant, wherein the first extractant is selected from trioxythiophene oxide, 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione, 1,1,1,2,2-pentafluoro-6,6-dimethyl-3,5-heptanedione, 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione, benzoyl trifluoroacetone, 1-phenyl-1,3-butanedione, 1 -benzoyl-2-nonanone, the second extractant is selected from trialkyl phosphates, trialkyl phosphine oxides, trioctyl phosphine oxide, trihexyl phosphine oxide, dialkyl phosphates, methyl isobutyl ketone, 1-phenylazo-2-naphthol, n-octanol, isooctyl alcohol, 2-ethylhexanol, 14-crown-4 ether butyl phosphonic acid dibutyl ester, butyl phosphate dibutyl ester, methylene tetrabutyl diphosphate, trioctylamine oxide, 1,10-phenanthroline, quaternary ammonium salt N 263 , dimethyldi(N-octadecyl)ammonium chloride, methyl dioctylsulfonium chloride, and 1-hydroxyethyl-3-methylimidazole bis(trifluoromethylsulfonyl)imide.

4. The lithium extraction method based on extraction-strip extraction according to claim 3, characterized in that: The volume ratio of the first extractant to the second extractant is 1:2-2:

1.

5. The lithium extraction method based on extraction-strip extraction according to claim 1, characterized in that: The volume fraction of the diluent in the composite extract is 40%-60%.

6. The lithium extraction method based on extraction-strip extraction according to claim 1, characterized in that: In the step of introducing CO2 into the lithium-loaded oil phase for mixing, the introduction pressure of CO2 is 0.2MPa-0.5MPa.

7. The lithium extraction method based on extraction-strip extraction according to claim 1, characterized in that: In the step of introducing CO2 into the lithium-loaded oil phase for mixing, the mixing temperature is 20°C-30°C and the mixing time is 1 min-3 min.

8. The lithium extraction method based on extraction-strip extraction according to claim 1, characterized in that: In the step of mixing the gas-liquid mixture with water for stripping, the mixing temperature is 20° C.-30° C., and the mixing time is 2 min-4 min.

9. The lithium extraction method based on extraction-strip extraction according to claim 1, characterized in that: Step S2 also obtains an empty composite extract, which is circulated to step S1 for use.

10. The lithium extraction method based on extraction-strip extraction according to claim 1, characterized in that: Step S3 also obtains lithium precipitation mother liquor and CO2, CO2 is circulated to step S2 for use, and the lithium precipitation mother liquor is circulated to step S1 and / or step S2 for use.

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