Compound extracting agent for lithium-containing solution and method for extracting lithium in solution

Abstract

The invention relates to a compound extraction agent of a lithium-containing solution and an extraction method of lithium in the solution, in particular to the field of lithium resource utilization, and the compound extraction agent comprises a neutral phosphine extraction agent, a phenolic ketone extraction agent and a beta-diketone extraction agent in a volume ratio of (3-5): 1: (1-5). According to the compound extracting agent provided by the invention, efficient extraction of the lithium element in a solution is realized through the synergistic effect of the extracting agents, the utilization effect of lithium is ensured, the extraction rate of lithium is greater than or equal to 99%, and the reverse extraction rate of lithium is greater than or equal to 99%.

Description

Technical Field

[0001] The present invention relates to the field of lithium resource utilization, and specifically designs a compound extraction agent for lithium-containing solutions and a method for extracting lithium from the solutions. Background Art

[0002] Clay-type lithium ores, also known as sedimentary lithium ores, are characterized by wide distribution, large reserves, and great enrichment difficulty. With the rapid increase in lithium demand, the development and utilization of clay-type lithium ores have received extensive attention. Clay-type lithium ores are often associated with bauxite and coal mines, and contain various associated elements such as aluminum, silicon, iron, titanium, calcium, and potassium, having high comprehensive development value.

[0003] Currently, the development and utilization of clay-type lithium ores mainly focus on laboratory research. Existing extraction methods mainly include ion exchange method, direct acid leaching method, acidification roasting - water leaching method, roasting activation - acid leaching method, and additive roasting - water leaching / acid leaching method.

[0004] For example, CN110358934A discloses a method for extracting lithium from carbonate clay-type lithium ores by the ion exchange method, proposing a new process of roasting activation - lithium exchange with iron salt solution, and the lithium extraction rate can reach over 90%.

[0005] CN116477858A discloses a method for preparing battery-grade lithium carbonate by pressure leaching of clay-type lithium ores, proposing a new process of pressure leaching of lithium with nitric acid, and separating and extracting lithium and aluminum by membrane separation method to finally obtain battery-grade lithium carbonate and industrial-grade alumina.

[0006] CN117926032A proposes a new process of sulfuric acid roasting and ripening - water leaching for lithium extraction, and obtaining lithium carbonate products by using sodium carbonate precipitation method, with the overall comprehensive recovery rate of Li reaching over 90%. CN118062865A discloses a method for extracting lithium by low-temperature acidification reaction of clay-type lithium ores, and finally obtaining lithium carbonate products by precipitation method, with the comprehensive lithium recovery rate of this method being above 85%.

[0007] CN116240399A discloses a method for selectively leaching lithium from clay-type lithium ores, proposing a new process of roasting activation - fluoride salt leaching for lithium, and obtaining a relatively pure lithium-containing leaching solution.

[0008] However, although the above research methods are diverse, there are still problems such as high cost, harsh leaching conditions, large acid consumption, complex filtrate composition, difficult extraction, and poor extraction effect. In addition, the existing technologies mainly focus on the extraction of lithium from clay-type lithium ores, and do not conduct comprehensive resource utilization of clay-type lithium ores, with low utilization efficiency of valuable elements in the original ore and tailings, and the comprehensive value of clay-type lithium ores not being fully exerted.

[0009] Therefore, it is particularly crucial to develop a technology that can comprehensively utilize clay-type lithium ores. This not only helps to achieve the efficient extraction of lithium resources, promote the sustainable and healthy development of the lithium-ion battery and energy storage industries, but also improves the synchronous extraction and comprehensive utilization efficiency of associated elements. Summary of the Invention

[0010] In view of the problems existing in the prior art, the purpose of the present invention is to provide a compound extraction agent for lithium-containing solutions and a method for extracting lithium from the solution, so as to solve the defect of poor extraction effect in the lithium recovery process.

[0011] To achieve this purpose, the present invention adopts the following technical solutions:

[0012] In the first aspect, the present invention provides a compound extraction agent for lithium-containing solutions, and the compound extraction agent includes:

[0013] A neutral phosphine extractant, a phenone extractant, and a β-diketone extractant with a volume ratio of (3-5):1:(1-5);

[0014] The phenone extractant has a structure shown in Formula I:

[0015]

[0016] In Formula I, R1 is selected from one of aryl groups with C6-C 12 , linear alkyl groups or branched alkyl groups with C1-C5, R2 is selected from one of hydrogen, linear alkyl groups or branched alkyl groups with C1-C3, R3 is selected from hydrogen or nitro, R4 is selected from one of hydrogen, hydroxyl groups, alkoxy groups with C1-C8, linear alkyl groups or branched alkyl groups with C1-C8, and R5 is selected from one of hydrogen, linear alkyl groups or branched alkyl groups with C1-C3;

[0017] The β-diketone extractant has a structure shown in Formula II:

[0018]

[0019] In Formula II, R x is selected from one of aryl groups with C6-C 12 , heteroaryl groups with C3-C 12 , linear alkyl groups or branched alkyl groups with C1-C8, R y is selected from substituted or unsubstituted aryl groups with C6-C 12 , substituted or unsubstituted linear alkyl groups or branched alkyl groups with C1-C 12 , and the substituents of the substituted ones are each independently selected from at least one of fluorine, linear alkyl groups or branched alkyl groups with C1-C 12 , and aryl groups with C6-C 12 .

[0020] The compound extractant provided by the present invention realizes the efficient extraction of lithium elements in the solution through the synergistic cooperation effect among the extractants, ensures the utilization effect of lithium, and is conducive to the comprehensive utilization of clay-type lithium ore resources.

[0021] As a preferred technical solution of the present invention, the neutral phosphine extractant includes one or a combination of at least two of tributyl phosphate, trioctylphosphine oxide or trialkylphosphine oxide.

[0022] As a preferred technical solution of the present invention, the phenone extractant includes one or a combination of at least two of 2-hydroxy-5-nitro-4-n-octyloxybenzophenone, o-hydroxyacetophenone or 2,4-dihydroxyacetophenone.

[0023] As a preferred technical solution of the present invention, R in the β-diketone extractant y is selected from phenyl, phenyl substituted by C1-C 12 linear alkyl or branched alkyl, phenyl substituted by C1-C 12 linear alkyl or branched alkyl, C1-C substituted by fluorine 12 linear alkyl or branched alkyl, C1-C substituted by phenyl 12 linear alkyl or branched alkyl.

[0024] Preferably, the β-diketone extractant includes one or a combination of at least two of dodecylphenyl-methyl-β-diketone, benzoyltrifluoroacetone or 2-thienoyltrifluoroacetone.

[0025] In a second aspect, the present invention provides a method for extracting lithium in a solution. The extraction method includes: extracting the lithium-containing solution with the compound extractant as described in the first aspect.

[0026] As a preferred technical solution of the present invention, the volume ratio of the compound extractant to the diluent used in the extraction is 1:(1-4).

[0027] Preferably, the pH value of the lithium-containing solution at the beginning of the extraction is 12-13.

[0028] Preferably, the phase ratio of the organic phase to the lithium-containing solution in the extraction is 1:(1-10).

[0029] As a preferred technical solution of the present invention, the temperature of the extraction is 15-30°C.

[0030] Preferably, the number of extraction stages ≥ 2.

[0031] As a preferred technical solution of the present invention, the extraction time ≥ 1 min.

[0032] As a preferred technical solution of the present invention, after the extraction is completed, phase separation is carried out to obtain a loaded organic phase, and the loaded organic phase is subjected to back extraction, which includes: mixing the loaded organic phase and the aqueous phase according to a volume ratio of (1-30):1 and introducing a gas phase until the back extraction equilibrium pH value is 6-8.

[0033] Preferably, the back extraction solution obtained by back extraction is heated at a temperature of 70-90°C for 0.5-2 h to obtain a lithium carbonate product.

[0034] As a preferred technical solution of the present invention, the lithium-containing solution includes the leaching solution of clay-type lithium ore.

[0035] Preferably, the leaching solution is obtained by subjecting the clay-type lithium ore to calcination roasting, followed by leaching and solid-liquid separation.

[0036] Preferably, the calcium additives used in the calcination roasting include one or a combination of at least two of calcium oxide, calcium hydroxide, calcium bicarbonate or calcium carbonate.

[0037] Preferably, the mass ratio of the clay-type lithium ore to the calcium additive in the calcination roasting is 1:(0.1-0.5).

[0038] Preferably, the temperature of the calcination roasting is 600-800°C.

[0039] Preferably, the time of the calcination roasting is 0.5-2 h.

[0040] Preferably, the leaching medium used in the leaching includes water.

[0041] Preferably, the mass ratio of the solid phase to the liquid phase in the leaching is 1:(3-7).

[0042] Preferably, the temperature of the leaching is 70-100°C.

[0043] Preferably, the time of the leaching is 0.5-3 h.

[0044] Preferably, the slag phase obtained by the solid-liquid separation is subjected to alkali leaching to obtain a sodium aluminate solution and a calcium-silicon tailing slag.

[0045] Preferably, the mass ratio of the solid phase to the liquid phase in the alkali leaching is 1:(3-8).

[0046] Preferably, the concentration of the alkali solution used in the alkali leaching is 100-300 g / L.

[0047] Preferably, the temperature of the alkali leaching is 180-260°C.

[0048] Preferably, the time of the alkali leaching is 0.5-3 h.

[0049] Compared with the existing technical solutions, the present invention has the following beneficial effects:

[0050] (1) The compound leaching agent provided by the present invention realizes the efficient extraction of lithium in the solution by virtue of the synergistic effect of each extractant. The extraction rate is ≥95.18%, and the extraction rate can reach more than 99% under the preferred extractant formula. The efficient stripping is realized by means of gas-liquid-liquid three-phase stripping, and the stripping rate of lithium is ≥99%.

[0051] (2) The method provided by the present invention can obtain a lithium-containing solution and leaching residues by adding a calcium-containing auxiliary agent and mixing and roasting with clay-type lithium ore and then using a one-step water leaching method. At the same time, elements such as Al and Si are fixed in the residues, realizing the efficient selective leaching of lithium. The obtained leaching solution is a weakly alkaline solution with a pH of 12-13, and battery-grade lithium carbonate can be directly obtained through extraction, CO2 stripping, and heating. The leaching residues can obtain a sodium aluminate solution with a relative dissolution rate of Al of 97% after high-pressure alkali leaching. The solution basically does not contain Si and can be directly used for the subsequent extraction of Al, and the tailings can be used as raw materials for building cement, realizing the efficient separation, extraction, and comprehensive utilization of valuable elements in clay-type lithium ore.

[0052] (3) The method provided by the present invention does not use strong acids during the leaching and extraction processes, is not easy to corrode equipment, and is green and environmentally friendly. In addition, introducing a calcium-containing auxiliary agent in the front-end roasting process can not only fix Si in the solid phase instead of Na during the alkali leaching process but also reduce the dissolution temperature and alkali consumption of high-pressure alkali leaching, obtaining tailings mainly composed of calcium aluminosilicate instead of sodium aluminosilicate, which can be directly used as building cement materials; the entire process flow is simple, environmentally friendly, low-cost, and has good industrial application prospects. Description of the Drawings

[0053] Figure 1 is the process flow diagram of the method for clay-type lithium ore in the embodiment of the present invention.

[0054] The present invention will be further described in detail below. However, the following examples are merely simple examples of the present invention and do not represent or limit the scope of the patent protection of the present invention. The scope of protection of the present invention shall be subject to the claims. Detailed Embodiments

[0055] To better illustrate the present invention and facilitate understanding of the technical solutions of the present invention, the typical but non-limiting embodiments of the present invention are as follows:

[0056] This embodiment provides a compound extractant for a lithium-containing solution. The compound extractant includes:

[0057] A neutral phosphine extractant, a phenol ketone extractant, and a β-diketone extractant with a volume ratio of (3-5):1:(1-5).

[0058] In the present invention, the volume ratio of the neutral phosphine extractant, the phenol-ketone extractant, and the β-diketone extractant in the composite extractant is (3 - 5):1:(1 - 5). For example, it can be 3:1:1, 3.5:1:1, 4:1:1, 3:1:2, 3:1:3, 3:1:4, 3:1:5, 3.5:1:2, 3.5:1:3, 3.5:1:4, 3.5:1:5, 4:1:2, 4:1:3, 4:1:4, 4:1:5, 3:1:5, 4:1:5, 5:1:5, 5:1:1, 5:1:2, 5:1:3, or 5:1:4, etc. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0059] Among them, the structural formula of the neutral phosphine extractant is as follows:

[0060]

[0061] In the formula, A1, A2, and A3 are each independently selected from one of C1 - C5 alkoxy groups, C1 - C8 straight-chain alkyl groups, or branched-chain alkyl groups. Exemplarily, it can be one or a combination of at least two of tributyl phosphate (TBP), trioctylphosphine oxide (TOPO), or trialkylphosphine oxide (TRPO).

[0062] In the present invention, the number of carbon atoms in the C1 - C5 alkoxy group is C1, C2, C3, C4, or C5, etc. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0063] In the present invention, the number of carbon atoms in the C1 - C8 straight-chain alkyl group or branched-chain alkyl group is C1, C2, C3, C4, C5, C6, C7, or C8, etc. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0064] Exemplarily, the combinations of neutral phosphine extractants are: a combination of tributyl phosphate and trioctylphosphine oxide, a combination of trioctylphosphine oxide and trialkylphosphine oxide, a combination of tributyl phosphate and trialkylphosphine oxide, etc.

[0065] Among them, the structural formula of the phenol-ketone extractant is as follows:

[0066]

[0067] In the formula, R1 is selected from C6 - C 12R2 is selected from one of hydrogen, C1-C3 straight chain alkyl or branched chain alkyl, R3 is selected from hydrogen or nitro, R4 is selected from one of hydrogen, hydroxyl, C1-C8 alkoxy, C1-C8 straight chain alkyl or branched chain alkyl, R5 is selected from one of hydrogen, C1-C3 straight chain alkyl or branched chain alkyl; illustratively, such as: 2-hydroxy-5-nitro-4-n-octyloxybenzophenone, o-hydroxyacetophenone or 2,4-dihydroxyacetophenone, one or a combination of at least two.

[0068] In the present invention, C6-C 12 The number of carbon atoms in the aromatic group is C6, C7, C8, C9, C 10 , C 11 , C 12 The above values are not limited to the above values, and other values not listed in the above values are also applicable.

[0069] In the present invention, the carbon number of the C1-C5 straight-chain alkyl or branched-chain alkyl is C1, C2, C3, C4 or C5, etc., but is not limited to the listed values, and other unlisted values within the range are also applicable.

[0070] In the present invention, the carbon number of the C1-C3 straight chain alkyl or branched chain alkyl is C1, C2 or C3, etc., but is not limited to the listed values, and other unlisted values within the range are also applicable.

[0071] In the present invention, the carbon number of the C1-C8 alkoxy group is C1, C2, C3, C4, C5, C6, C7 or C8, but is not limited to the listed values, and other unlisted values within the range are also applicable.

[0072] Illustratively, the combination of phenolic ketone extractants is: a combination of 2-hydroxy-5-nitro-4-octyloxybenzophenone and o-hydroxyacetophenone, a combination of o-hydroxyacetophenone and 2,4-dihydroxyacetophenone, a combination of 2-hydroxy-5-nitro-4-octyloxybenzophenone and 2,4-dihydroxyacetophenone, and the like.

[0073] Wherein, the structural formula of the β-diketone extractant is as follows:

[0074]

[0075] In the formula, R x Selected from C6-C 12 Aryl, C3-C 12 A heteroaryl group, a C1-C8 straight-chain alkyl group or a branched-chain alkyl group, R y Selected from substituted or unsubstituted C6-C 12 Aryl, substituted or unsubstituted C1-C 12One of a linear alkyl group or a branched alkyl group, wherein each of the substituted substituents is independently selected from fluorine, C1-C 12 a linear alkyl group or a branched alkyl group, C6-C 12 at least one of an aryl group, preferably R y selected from a phenyl group, C1-C 12 a phenyl group substituted with a linear alkyl group or a branched alkyl group, C1-C 12 a linear alkyl group or a branched alkyl group, a C1-C linear alkyl group or a branched alkyl group substituted with fluorine 12 a linear alkyl group or a branched alkyl group, a C1-C linear alkyl group or a branched alkyl group substituted with a phenyl group 12 One of a linear alkyl group or a branched alkyl group; for example, one or at least two combinations of dodecylphenyl-methyl-β-diketone, benzoyltrifluoroacetone or 2-thienoyltrifluoroacetone.

[0076] In the present invention, the number of carbon atoms of the heteroaryl group of C3-C 12 is C3, C4, C5, C6, C7, C8, C9, C 10 , C 11 , C 12 etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0077] In the present invention, the number of carbon atoms of the linear alkyl group or the branched alkyl group of C1-C 12 is C1, C2, C3, C4, C5, C6, C7, C8, C9, C 10 , C 11 , C 12 etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0078] In the present invention, the number of carbon atoms of the fluorine-substituted linear alkyl group or the branched alkyl group of C1-C8 is C1, C2, C3, C4, C5, C6, C7 or C8, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0079] Exemplarily, the combinations of β-diketone extractants are: the combination of dodecylphenyl-methyl-β-diketone and benzoyltrifluoroacetone, the combination of benzoyltrifluoroacetone and 2-thienoyltrifluoroacetone, the combination of dodecylphenyl-methyl-β-diketone and 2-thienoyltrifluoroacetone, etc.

[0080] As a preferred embodiment, when the complex extraction is selected as trialkylphosphine oxide, 2-hydroxy-5-nitro-4-n-octyloxybenzophenone and dodecylphenyl-methyl-β-diketone with a volume ratio of (4-5):1:(4-5), it has a more excellent extraction effect on the lithium solution, and the extraction rate ≥ 99%.

[0081] Further, this embodiment provides an extraction method based on the aforementioned compound extractant, and the overall process is as follows Figure 1 as shown, specifically as follows:

[0082] Use the aforementioned compound extractant to extract the lithium-containing solution.

[0083] Among them, the lithium-containing solution refers to a solution containing lithium element. Exemplarily, it can be a leaching solution, a recovery solution, a configured solution, or other lithium-containing liquids.

[0084] Among them, the leaching solution refers to the liquid phase obtained by directly leaching lithium-containing materials (such as raw ore, recovered materials, waste residues, calcined slag, etc.), or leaching after calcination, or leaching after being treated by conventional treatment methods in this field, and then through solid-liquid separation.

[0085] Exemplarily, the process of obtaining the leaching solution is as follows:

[0086] Perform calcification roasting on the clay-type lithium ore, and then obtain it through leaching and solid-liquid separation.

[0087] Among them, the calcium additives used in the calcification roasting include: one or a combination of at least two of calcium oxide, calcium hydroxide, calcium bicarbonate, or calcium carbonate.

[0088] Exemplarily, the combination of calcium additives can be selected as the combination of calcium oxide and calcium hydroxide, the combination of calcium hydroxide and calcium bicarbonate, the combination of calcium bicarbonate and calcium carbonate, the combination of calcium oxide and calcium carbonate, etc.

[0089] Among them, the mass ratio of the clay-type lithium ore to the calcium additive in the calcification roasting is 1:(0.1 - 0.5). For example, it can be 1:0.1, 1:0.2, 1:0.3, 1:0.4, or 1:0.5, etc., but it is not limited to the listed values, and other unlisted values within this range are also applicable.

[0090] Among them, the temperature of the calcification roasting is 600 - 800 °C. For example, it can be 600 °C, 650 °C, 700 °C, 750 °C, or 800 °C, etc., but it is not limited to the listed values, and other unlisted values within this range are also applicable.

[0091] Among them, the time of the calcification roasting is 0.5 - 2 h. For example, it can be 0.5 h, 1.0 h, 1.5 h, or 2.0 h, etc., but it is not limited to the listed values, and other unlisted values within this range are also applicable.

[0092] Among them, the leaching medium used in the leaching includes water.

[0093] Among them, the mass ratio of the solid phase to the liquid phase in the leaching is 1:(3 - 7). For example, it can be 1:3, 1:4, 1:5, 1:6 or 1:7, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0094] Among them, the temperature of the leaching is 70 - 100 °C. For example, it can be 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 95 °C or 100 °C, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0095] Among them, the time of the leaching is 0.5 - 3 h. For example, it can be 0.5 h, 1.0 h, 1.5 h, 2.0 h, 2.5 h or 3.0 h, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0096] Among them, the slag phase obtained by solid-liquid separation is subjected to alkali leaching to obtain sodium aluminate solution and calcium-silicon tailings.

[0097] Among them, the mass ratio of the solid phase to the liquid phase in the alkali leaching is 1:(3 - 8). For example, it can be 1:3, 1:4, 1:5, 1:6, 1:7 or 1:8, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0098] Among them, the concentration of the alkali solution used in the alkali leaching is 100 - 300 g / L. For example, it can be 100 g / L, 150 g / L, 200 g / L, 250 g / L or 300 g / L, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0099] Among them, the temperature of the alkali leaching is 180 - 260 °C. For example, it can be 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C or 260 °C, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0100] Among them, the time of the alkali leaching is 0.5 - 3 h. For example, it can be 0.5 h, 1.0 h, 1.5 h, 2.0 h, 2.5 h or 3.0 h, but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0101] Among them, the recycled liquid refers to the lithium-containing liquid recovered from the lithium utilization end, such as the process of preparing lithium solution, lithium materials, electrolyte, electrode liquid, etc.

[0102] Among them, the prepared solution refers to the solution obtained by dissolving existing lithium materials such as lithium salts in water, acid solution, or alkali solution.

[0103] Among them, the volume ratio of the compound extraction agent to the diluent used in the extraction is 1:(1 - 4). For example, it can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5 or 1:4, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0104] In the present invention, the diluent used for the compound extraction agent in the extraction can be selected from diluents of commonly used extraction agents in the art, such as sulfonated kerosene, kerosene, etc.

[0105] Among them, the pH value of the lithium-containing solution at the beginning of the extraction is 12 - 13. For example, it can be 12, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9 or 13, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0106] Among them, the phase ratio of the organic phase to the lithium-containing solution in the extraction is 1:(1 - 10). For example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0107] In the present invention, the organic phase in the extraction refers to the material after mixing the compound extraction agent and the diluent.

[0108] Among them, the temperature of the extraction is 15 - 30 °C. For example, it can be 15 °C, 16 °C, 18 °C, 20 °C, 22 °C, 24 °C, 26 °C, 28 °C or 30 °C, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0109] Among them, the number of extraction stages ≥ 2. For example, it can be 2 stages, 3 stages, 4 stages, 5 stages, 6 stages, 7 stages, 8 stages, 9 stages or 10 stages, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0110] In the present invention, the extraction method can be selected as co-current extraction or counter-current extraction, etc.

[0111] Among them, the extraction time ≥ 1 min. For example, it can be 1 min, 2 min, 4 min, 6 min, 8 min, 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, 25 min or 30 min, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0112] After extraction, phase separation is carried out to obtain a loaded organic phase, and the loaded organic phase is subjected to back-extraction. The back-extraction includes: mixing the loaded organic phase and an aqueous phase at a volume ratio of (1 - 30):1 and introducing a gas phase until the back-extraction equilibrium pH value is 6 - 8.

[0113] In the present invention, the gas phase used in the back-extraction process is a commonly used gas phase in the art, such as carbon dioxide.

[0114] In the present invention, the volume ratio of the mixed loaded organic phase to the aqueous phase is (1 - 30):1. For example, it can be 1:1, 2:1, 4:1, 6:1, 8:1, 10:1, 15:1, 20:1, 25:1 or 30:1, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0115] In the present invention, the back-extraction equilibrium pH value is 6 - 8. For example, it can be 6, 6.5, 7, 7.5 or 8, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0116] Among them, the back-extraction solution obtained by back-extraction is heated at a temperature of 70 - 90 °C for 0.5 - 2 h to obtain a lithium carbonate product.

[0117] Among them, the heating temperature for preparing the lithium carbonate product from the back-extraction solution is 70 °C, 72 °C, 74 °C, 76 °C, 78 °C, 80 °C, 82 °C, 84 °C, 86 °C, 88 °C or 90 °C, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0118] Among them, the heating time for preparing the lithium carbonate product from the back-extraction solution is 0.5 - 2 h. For example, it can be 0.5 h, 0.6 h, 0.8 h, 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h or 2 h, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0119] Furthermore, in order to illustrate the extraction effect that can be achieved by the provided complex extraction agent of the present invention, the following actual examples are used for exemplary illustration, specifically as follows:

[0120] The clay-type lithium ore used in the following examples comes from a certain area in Yunnan, China. The specific chemical composition is shown in Table 1 below in mass percentage.

[0121] Table 1

[0122] Component <![CDATA[Al2O3]]> <![CDATA[SiO2]]> <![CDATA[Fe2O3]]> <![CDATA[TiO2]]> CaO <![CDATA[K2O]]> MgO <![CDATA[Li2O <!-- 7 -->]]> Content (wt%) 57.12 13.64 6.93 2.68 1.06 1.86 0.88 0.84

[0123] Example 1

[0124] This example provides a specific usage example of the aforementioned complex extraction agent. The flowchart is as Figure 1 shown, specifically as follows:

[0125] (1) The clay-type lithium ore powder and calcium oxide were fully mixed in a mass ratio of 2:1 and placed in a muffle furnace, heated to 800° C. for 2 h, and then naturally cooled and taken out;

[0126] (2) mixing the roasted ore powder obtained in step (1) with water at a solid-liquid ratio of 1:3, leaching at 90° C. for 3 h, and filtering to obtain a lithium-containing solution and leached residue;

[0127] (3) extracting the leaching solution (pH=12.8) obtained in step (2), wherein the ratio of the leaching solution to the extraction system is 3:1, the extraction level is 2, and the mixing time is 2 min; the extraction system is composed of a composite extractant trialkylphosphine oxide (TRPO), 2-hydroxy-5-nitro-4-n-octyloxybenzophenone, dodecylphenyl-methyl-β-diketone and a diluent kerosene, the volume ratio of trialkylphosphine oxide, 2-hydroxy-5-nitro-4-n-octyloxybenzophenone and dodecylphenyl-methyl-β-diketone in the composite extractant is 5:1:5, and the volume ratio of the composite extractant to kerosene is 3:7;

[0128] (4) adding water to the loaded organic phase obtained in step (3) and performing gas-liquid-liquid three-phase back extraction, using CO2 as the gas phase, the ratio of the loaded organic phase to the aqueous phase is 20:1, and the back extraction equilibrium pH = 8;

[0129] (5) heating the stripping solution obtained in step (4) at 90° C. for 2 h, filtering, and obtaining a lithium carbonate product;

[0130] (6) subjecting the leached residue obtained in step (2) to high-pressure alkali leaching, wherein the alkali leaching temperature is 240° C., the alkali leaching time is 2 h, the alkali leaching solid-liquid mass ratio is 1:3, and the NaOH solution concentration is 160 g / L.

[0131] Example 2

[0132] The only difference from Example 1 is that the composite extractant used is replaced with equal amounts of tributyl phosphate (TBP), o-hydroxyacetophenone, and benzoyltrifluoroacetone in a volume ratio of 3:1:1;

[0133] During the extraction process, the volume ratio of the compound extractant to the diluent was 3:5, the pH value of the lithium-containing solution at the beginning of the extraction was 12, the ratio of the leaching solution to the extraction system was 6:1, and the extraction level was 3.

[0134] Example 3

[0135] The only difference from Example 1 is that the composite extractant used is replaced with equal amounts of trialkylphosphine oxide (TRPO), 2,4-dihydroxyacetophenone, and 2-thenoyltrifluoroacetone in a volume ratio of 3:1:5;

[0136] During the extraction process, the volume ratio of the compound extractant to the diluent is 1:1. The pH value of the lithium-containing solution at the beginning of extraction is 13. The phase ratio of the leaching solution to the extraction system is 10:1, and the number of extraction stages is 4.

[0137] Example 4

[0138] The difference from Example 1 is only that the compound extractant used is replaced with an equal amount of trialkylphosphine oxide (TRPO), o-hydroxyacetophenone, and dodecylphenyl-methyl-β-diketone with a volume ratio of 4:1:3.

[0139] During the extraction process, the volume ratio of the compound extractant to the diluent is 1:4. The pH value of the lithium-containing solution at the beginning of extraction is 12.4. The phase ratio of the leaching solution to the extraction system is 1:1, and the number of extraction stages is 5.

[0140] Example 5

[0141] The difference from Example 1 is only that the volume ratio of trialkylphosphine oxide (TRPO), 2-hydroxy-5-nitro-4-n-octyloxydibenzoyl methane, and dodecylphenyl-methyl-β-diketone in the compound extractant is 3:1:5.

[0142] Example 6

[0143] The difference from Example 1 is only that the volume ratio of trialkylphosphine oxide (TRPO), 2-hydroxy-5-nitro-4-n-octyloxydibenzoyl methane, and dodecylphenyl-methyl-β-diketone in the compound extractant is 5:1:3.

[0144] Comparative Example 1

[0145] The difference from Example 1 is only that the compound extractant used is replaced with an equal amount of trialkylphosphine oxide (TRPO), 2-hydroxy-5-nitro-4-n-octyloxydibenzoyl methane, and dodecylphenyl-methyl-β-diketone with a volume ratio of 6:1:5.

[0146] Comparative Example 2

[0147] The difference from Example 1 is only that the compound extractant used is replaced with an equal amount of trialkylphosphine oxide (TRPO), 2-hydroxy-5-nitro-4-n-octyloxydibenzoyl methane, and dodecylphenyl-methyl-β-diketone with a volume ratio of 5:1:6.

[0148] Comparative Example 3

[0149] The difference from Example 1 is only that the compound extractant used is replaced with an equal amount of trialkylphosphine oxide (TRPO) and 2-hydroxy-5-nitro-4-n-octyloxydibenzoyl methane with a volume ratio of 5:1.

[0150] Comparative Example 4

[0151] The difference from Example 1 is only that the compound extraction agent used is replaced with an equal amount of dodecylphenyl-methyl-β-diketone and 2-hydroxy-5-nitro-4-n-octyloxybenzophenone with a volume ratio of 5:1.

[0152] Comparative Example 5

[0153] The difference from Example 1 is only that the compound extraction agent used is replaced with an equal amount of trialkylphosphine oxide (TRPO) and dodecylphenyl-methyl-β-diketone with a volume ratio of 1:1.

[0154] Comparative Example 6

[0155] The difference from Example 1 is only that the compound extraction agent used is replaced with an equal amount of dodecylphenyl-methyl-β-diketone.

[0156] Comparative Example 7

[0157] The difference from Example 1 is only that the compound extraction agent used is replaced with an equal amount of trialkylphosphine oxide (TRPO).

[0158] Comparative Example 8

[0159] The difference from Example 1 is only that the compound extraction agent used is replaced with an equal amount of 2-hydroxy-5-nitro-4-n-octyloxybenzophenone.

[0160] Comparative Example 9

[0161] The difference from Example 1 is only that the compound extraction agent used is replaced with an equal amount of trialkylphosphine oxide (TRPO), 2-hydroxy-5-nitro-4-n-octyloxybenzophenone, and dodecylphenyl-methyl-β-diketone with a volume ratio of 1:5:1.

[0162] Comparative Example 10

[0163] The difference from Example 1 is only that the trialkylphosphine oxide is replaced with an equal amount of D2EHPA.

[0164] Comparative Example 11

[0165] The difference from Example 1 is only that the 2-hydroxy-5-nitro-4-n-octyloxybenzophenone is replaced with an equal amount of methyl isobutyl ketone.

[0166] Comparative Example 12

[0167] The difference from Example 1 is only that the dodecylphenyl-methyl-β-diketone is replaced with an equal amount of ferric chloride.

[0168] Comparative Example 13

[0169] The difference from Example 1 is only that dodecylphenyl-methyl-β-diketone is replaced with an equal amount of sodium perchlorate.

[0170] The results of the leaching rates of lithium, aluminum, silicon, magnesium, and iron, the extraction rate of lithium, the stripping rate, the total recovery rate, and the relative dissolution rate of aluminum in the leaching residue in the above-mentioned examples and comparative examples are shown in Table 2.

[0171] Table 2

[0172]

[0173]

[0174] From the results of the above examples, it can be seen that the method provided by the present invention, on the basis of efficiently and selectively extracting lithium from clay-type lithium ore, the obtained leaching solution does not need to adjust the pH, and can directly obtain a lithium-rich solution through solvent extraction-CO2 stripping method, and then obtain battery-grade lithium carbonate by heating the lithium-rich solution. In addition, after high-pressure alkaline leaching of the leaching residue, a sodium aluminate solution with a relative dissolution rate of aluminum of 97% can be obtained. The solution basically does not contain Si and can be directly used for the subsequent extraction of Al, and the calcium-silicon tailings can also be reused as raw materials for building cement, realizing the comprehensive utilization of clay-type lithium ore as a whole.

[0175] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0176] In addition, it should be noted that, among the various specific technical features described in the above specific embodiments, they can be combined in any appropriate manner without conflict. In order to avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0177] Furthermore, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, it should also be regarded as the content disclosed by the present invention.

Claims

1. A compound extraction agent for lithium-containing solution, characterized in that, The compound extraction agent includes: A neutral phosphine extraction agent, a phenolic ketone extraction agent, and a β-diketone extraction agent with a volume ratio of (3-5):1:(1-5); The phenolic ketone extraction agent has a structure shown in Formula I: In formula I, R1 is selected from one of aryl groups having C6-C 12 , a straight-chain or branched alkyl group having C1-C5, R2 is selected from one of hydrogen, a straight-chain or branched alkyl group having C1-C3, R3 is selected from hydrogen or nitro, R4 is selected from one of hydrogen, hydroxy, an alkoxy group having C1-C8, a straight-chain or branched alkyl group having C1-C8, and R5 is selected from one of hydrogen, a straight-chain or branched alkyl group having C1-C3; The β-diketone extraction agent has a structure shown in Formula II: In formula II, R x is selected from an aryl group having 6 to 12 carbon atoms, a heteroaryl group having 3 to 12 carbon atoms, a straight-chain alkyl group or a branched-chain alkyl group having 1 to 8 carbon atoms, and R y is selected from a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, a substituted or unsubstituted straight-chain alkyl group or a branched-chain alkyl group having 1 to 12 carbon atoms, and the substituents of the substituted groups are each independently selected from at least one of fluorine, a straight-chain alkyl group or a branched-chain alkyl group having 1 to 12 carbon atoms, and an aryl group having 6 to 12 carbon atoms.

2. The compound extraction agent according to claim 1, wherein The neutral phosphine extraction agent includes one or a combination of at least two of tributyl phosphate, trioctylphosphine oxide, or trialkylphosphine oxide.

3. The compound extraction agent according to claim 1, wherein The phenolic ketone extraction agent includes one or a combination of at least two of 2-hydroxy-5-nitro-4-n-octyloxybenzophenone, o-hydroxyacetophenone, or 2,4-dihydroxyacetophenone.

4. The compound extraction agent according to claim 1, characterized in that, R in the β-diketone extractant y is selected from phenyl, C1-C 12 phenyl substituted with linear or branched alkyl, C1-C 12 linear or branched alkyl, C1-C substituted with fluorine 12 linear or branched alkyl, C1-C substituted with phenyl 12 one of linear or branched alkyl; Preferably, the β-diketone extraction agent includes one or a combination of at least two of dodecylphenyl-methyl-β-diketone, benzoyltrifluoroacetone, or 2-thienoyltrifluoroacetone.

5. A method for extracting lithium in a solution, characterized in that, The extraction method includes: extracting a lithium-containing solution with the compound extraction agent described in any one of claims 1-4.

6. The extraction method according to claim 5, wherein The volume ratio of the compound extraction agent to the diluent used in the extraction is 1:(1-4); Preferably, the pH value of the lithium-containing solution at the start of the extraction is 12-13; Preferably, the phase ratio of the organic phase to the lithium-containing solution in the extraction is 1:(1-10).

7. The extraction method according to any one of claims 5-6, characterized in that, The temperature of the extraction is 15-30 °C; Preferably, the number of extraction stages ≥ 2.

8. The extraction method according to any one of claims 5-7, characterized in that, The extraction time ≥ 1 min.

9. The extraction method according to any one of claims 5-8, characterized in that, After the extraction, phase separation is carried out to obtain a loaded organic phase, and the loaded organic phase is subjected to stripping. The stripping includes: mixing the loaded organic phase and the aqueous phase according to a phase ratio of (1-30):1 and introducing a gas phase until the stripping equilibrium pH value is 6-8; Preferably, the stripping solution obtained by stripping is heated at a temperature of 70-90 °C for 0.5-2 h to obtain a lithium carbonate product.

10. The extraction method according to any one of claims 5-8, characterized in that, The lithium-containing solution includes the leaching solution of clay-type lithium ore; Preferably, the leaching solution is obtained by subjecting the clay-type lithium ore to calcination roasting, followed by leaching and solid-liquid separation; Preferably, the calcium additives used in the calcination roasting include one or a combination of at least two of calcium oxide, calcium hydroxide, calcium bicarbonate, or calcium carbonate; Preferably, the mass ratio of the clay-type lithium ore to the calcium additive in the calcination roasting is 1:(0.1-0.5); Preferably, the temperature of the calcination roasting is 600-800 °C; Preferably, the time of the calcination roasting is 0.5-2 h; Preferably, the leaching medium used in the leaching includes water; Preferably, the mass ratio of the solid phase to the liquid phase in the leaching is 1:(3-7); Preferably, the temperature of the leaching is 70-100 °C; Preferably, the time of the leaching is 0.5-3 h; Preferably, the solid residue obtained by the solid-liquid separation is subjected to alkali leaching to obtain a sodium aluminate solution and a calcium-silicon tailing; Preferably, the mass ratio of the solid phase to the liquid phase in the alkali leaching is 1:(3-8); Preferably, the concentration of the alkali solution used in the alkali leaching is 100-300 g / L; Preferably, the temperature of the alkali leaching is 180-260 °C; Preferably, the time of the alkali leaching is 0.5-3 h.

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