Application of dialkyl phosphinic acid compound as extracting agent

Abstract

The invention belongs to the technical field of extraction agents, and particularly relates to application of a dialkyl phosphinic acid compound as an extraction agent. According to the application of the dialkyl phosphinic acid compound as the extraction agent, the dialkyl phosphinic acid compound has a structure as shown in a formula 1: # imgabs0 #, R1 to R4 are independently-H or first alkyl, and R1 and R2 cannot be-H at the same time; r5 and R6 are independently a second alkyl group; the total number of C atoms in the dialkyl phosphinic acid compound is 16 to 40. Alpha-C of a P atom in the dialkyl phosphinic acid compound has a branched chain, so that adjacent positions of polar groups P = O and P-OH have high steric hindrance, water molecules are difficult to approach the polar group part of the compound, and the extractant has good fat solubility and is not easy to form a water-in-oil emulsion. Polymers are not easy to form among molecules of the dialkyl phosphinic acid compound, and the dialkyl phosphinic acid compound does not need to be heated to 40 DEG C or above in the using process.

Description

Technical Field

[0001] The invention belongs to the technical field of extractants, and particularly relates to the application of a dialkylphosphinic acid compound as an extractant. Background Art

[0002] The non-ferrous metal industry mainly uses solvent extraction to separate, purify and enrich metals. The basic principle is that hydrophobic extractants containing specific functional groups have different binding abilities with various metal ions in aqueous solutions. The extractants selectively complex certain metal ions and transfer them from the aqueous phase to the organic phase, thereby achieving separation from other metal ions in the aqueous solution. The existing hydrometallurgical extractants mainly include acidic extractants, neutral extractants, alkaline extractants, and chelating extractants; among them, organic phosphorus (phosphonic) acid extractants are the most widely used, mainly di(2-ethylhexyl) phosphate (P204), 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507) and di(2,4,4-trimethylpentane)phosphonic acid (C272). Among them, C272 has become the main extractant in the field of hydrometallurgy due to its advantages such as high selectivity for certain metal ions, easy stripping, and high chemical stability.

[0003] With the continuous development of the power battery industry, the demand for cobalt-nickel-manganese ternary positive electrode materials is increasing, and thus the demand for its raw material high-purity manganese sulfate is also increasing. Most manganese slurries contain calcium. In the extraction metal sequence of P204 and P507, calcium is extracted before manganese, and the two are relatively close, so they cannot be separated; while in the extraction metal sequence of C272, manganese extraction takes precedence over calcium extraction, and the manganese line and calcium line are far apart, with a high Mn / Ca separation capacity, so fewer extraction, washing, and back extraction stages can achieve the separation of manganese and calcium and enrichment of manganese concentration, reducing the energy consumption of subsequent evaporation, concentration, and crystallization. However, C272 also has the following problems during use: (1) It needs to be used above 40°C, otherwise the extraction phase separation is very slow; (2) If the saponification rate is higher than 40%, the extraction process is very easy to emulsify and the phase separation is very slow, resulting in low saturation capacity and insufficient extraction capacity. In actual application, more extraction stages are often required, the amount of extractant used is large, and the investment cost is high. Summary of the invention

[0004] In view of this, the present invention provides an application of a dialkyl phosphinic acid compound as an extractant. The dialkyl phosphinic acid compound provided by the present invention is used as a hydrometallurgical extractant to efficiently separate and enrich metals in an extract at room temperature.

[0005] In order to solve the above technical problems, the present invention provides a dialkyl phosphinic acid compound as an extractant, wherein the dialkyl phosphinic acid compound has a structure shown in Formula 1:

[0006]

[0007] Wherein, R1 to R4 are independently -H or the first alkyl group, and R1 and R2 cannot be -H at the same time;

[0008] R5 and R6 are independently a second alkyl group;

[0009] The total number of C atoms in the dialkylphosphinic acid compound is 16-40.

[0010] Preferably, the extractant is a hydrometallurgical extractant.

[0011] Preferably, the temperature for extracting the dialkylphosphinic acid compound as a hydrometallurgical extractant is room temperature, and the room temperature is 15-30°C.

[0012] Preferably, the metal ions contained in the extracted solution include any two or more of nickel ions, cobalt ions, manganese ions, calcium ions and magnesium ions.

[0013] Preferably, the number of C atoms in the first alkyl group is 1-7.

[0014] Preferably, the first alkyl group includes methyl, propyl, butyl, heptyl or isopropyl.

[0015] Preferably, the second alkyl group includes butyl, pentyl, hexyl, heptyl or nonyl.

[0016] Preferably, the dialkylphosphinic acid compounds include di(1-methylheptyl)phosphinic acid, di(1-butylhexyl)phosphinic acid, di(1-propylpentyl)phosphinic acid, di(1-heptylnonyl)phosphinic acid, (1-methylheptyl)(1-butylhexyl)phosphinic acid, (1-methylheptyl)(1-propylpentyl)phosphinic acid, (1-methylheptyl)(1-heptylnonyl)phosphinic acid, (1-butylhexyl)(1-propylpentyl)phosphinic acid, (1-butylhexyl)(1-heptylnonyl)phosphinic acid, (1-propylpentyl)(1-heptylnonyl), di(1,2-dimethylpentyl)phosphinic acid, di (1,2-diethylbutyl)phosphinic acid, (1,2-dimethylpentyl) (1,2-diethylbutyl) phosphinic acid, (1-methylheptyl) (2-isopropylhexyl) phosphinic acid, (1-butylhexyl) (2-isopropylhexyl) phosphinic acid, (1-propylpentyl) (2-isopropylhexyl) phosphinic acid, (1-heptylnonyl) (2-isopropylhexyl) phosphinic acid, (1-methylheptyl) (2-ethylhexyl) phosphinic acid, (1-butylhexyl) (2-ethylhexyl) phosphinic acid, (1-propylpentyl) (2-ethylhexyl) phosphinic acid, (1-heptylnonyl) (2-ethylhexyl) phosphinic acid, (1-methylheptyl)(2,4,4-trimethylpentyl)phosphinic acid, (1-butylhexyl)(2,4,4-trimethylpentyl)phosphinic acid, (1-propylpentyl)(2,4,4-trimethylpentyl)phosphinic acid, (1-heptylnonyl)(2,4,4-trimethylpentyl)phosphinic acid, (1,2-dimethylpentyl)(1-methylheptyl)phosphinic acid, (1,2-diethylbutyl)(1-methylheptyl)phosphinic acid, (1,2-dimethylpentyl)(1-butylhexyl)phosphinic acid, (1,2-diethylbutyl)(1-butylhexyl)phosphinic acid, (1,2-dimethylpentyl)(1 -propylpentyl)phosphinic acid, (1,2-diethylbutyl)(1-propylpentyl)phosphinic acid, (1,2-dimethylpentyl)(1-heptylnonyl)phosphinic acid, (1,2-diethylbutyl)(1-heptylnonyl)phosphinic acid, (1,2-dimethylpentyl)(2-ethylhexyl)phosphinic acid, (1,2-diethylbutyl)(2-ethylhexyl)phosphinic acid, (1,2-dimethylpentyl)(2-isopropylhexyl)phosphinic acid, (1,2-dimethylpentyl)(2,4,4-trimethylpentyl)phosphinic acid or (1,2-diethylbutyl)(2,4,4-trimethylpentyl)phosphinic acid.

[0017] Preferably, the preparation method of the dialkylphosphinic acid compound comprises the following steps:

[0018] When R1 is the same as R2, R3 is the same as R4, and R5 is the same as R6, the preparation method of the dialkylphosphinic acid compound comprises the following steps;

[0019] Mixing hypophosphorous acid, compound 1 and a first initiator to perform a first addition reaction to obtain the dialkyl phosphinic acid compound;

[0020] When R1 and R2 are different, R3 and R4 are different, or R5 and R6 are different, the preparation method of the dialkylphosphinic acid compound comprises the following steps;

[0021] The hypophosphorous acid, compound 1 and a second initiator are mixed to carry out a second addition reaction to obtain a monoalkyl phosphinic acid compound;

[0022] The monoalkyl phosphinic acid, compound 2 and a third initiator are mixed to perform a third addition reaction to obtain the dialkyl phosphinic acid compound;

[0023]

[0024] Preferably, the temperature of the first addition reaction is 130-140°C and the time is 25-35h;

[0025] The temperature of the second addition reaction is 130-140° C. and the time is 7-9 hours;

[0026] The temperature of the third addition reaction is 130-140° C., and the time is 25-35 hours.

[0027] The present invention provides an application of a dialkyl phosphinic acid compound as an extractant, wherein the dialkyl phosphinic acid compound has a structure shown in Formula 1: Wherein, R1 to R4 are independently -H or the first alkyl group, and R1 and R2 cannot be -H at the same time; R5 and R6 are independently the second alkyl group; and the total number of C atoms in the dialkyl phosphinic acid compound is 16 to 40. The dialkyl phosphinic acid compound provided by the present invention has a hydrophobic and electron-repelling alkyl side chain on the α-C or on the α-C and β-C of the P atom. The introduction of such an alkyl side chain will bring the following advantages to the performance of the extractant: (1) the positions adjacent to the polar groups P=O and P-OH have a higher hydrophobic steric hindrance, making it difficult for water molecules to approach the polar group part of the extractant molecule, so that it is not easy to form an oil-in-water emulsion during the extraction process, and further the dialkyl phosphinic acid compound has a higher saponification rate and a larger saturation capacity; (2) the steric hindrance caused by the hydrophobic alkyl chain on the α-C also weakens the attraction and hydrogen bonding between adjacent extractant molecules, making it difficult to form polymers, thereby reducing the viscosity of the dialkyl phosphinic acid compound, so there is no need to increase the extraction system during use. of the temperature to improve the fluidity of the extractant; (3) the electron-repelling alkyl side chain on the α-C will increase the electron cloud density on the polar group (which is also the functional group that complexes with specific metal ions), thereby further weakening the acidity of the entire dialkyl phosphinic acid compound. This not only improves the selectivity of the dialkyl phosphinic acid compound as an extractant for metal ions, but also makes it easier to strip the loaded organic phase, thereby significantly improving its comprehensive extraction and separation performance; (4) the hydrophobic alkyl side chain on the α-C further increases the hydrophobicity of the dialkyl phosphinic acid compound itself and the extractant, reduces its solubility in water and the loss of the extractant, and also reduces the organic COD of the raffinate wastewater. At the same time, it increases the solubility of the extractant in the alkane diluent with very low polarity, so that a higher concentration of extractant can be prepared in the actual extraction production process. Therefore, the dialkyl phosphinic acid compounds provided by the present invention effectively solve the problems of the C272 extractant in the extraction process, such as high water solubility of the extraction system, difficult phase separation, easy emulsification, low capacity, and the need for heating during the extraction process. The compounds provided by the present invention can replace all application scenarios of C272, overcoming the inherent defects of the C272 extractant. DETAILED DESCRIPTION

[0028] The present invention provides an application of a dialkyl phosphinic acid compound as an extractant, wherein the dialkyl phosphinic acid compound has a structure shown in Formula 1:

[0029]

[0030] Wherein, R1 to R4 are independently -H or the first alkyl group, and R1 and R2 cannot be -H at the same time;

[0031] R5 and R6 are independently a second alkyl group.

[0032] In the present invention, the number of C atoms in the first alkyl group is preferably 1 to 7, more preferably 3 to 7; the first alkyl group is preferably methyl, propyl, butyl, heptyl or isopropyl. In the present invention, the second alkyl group preferably includes butyl, pentyl, hexyl, heptyl or nonyl. In the present invention, the total number of C atoms in the dialkylphosphinic acid compound is preferably 16 to 40, more preferably 16 to 24.

[0033] In the present invention, the dialkylphosphinic acid compound preferably has structures as shown in A to E:

[0034]

[0035] In the present invention, the dialkyl phosphinic acid compound having the structure shown in formula A preferably includes di(1-methylheptyl)phosphinic acid, di(1-butylhexyl)phosphinic acid, di(1-propylpentyl)phosphinic acid, di(1-heptylnonyl)phosphinic acid, (1-methylheptyl)(1-butylhexyl)phosphinic acid, (1-methylheptyl)(1-propylpentyl)phosphinic acid, (1-methylheptyl)(1-heptylnonyl)phosphinic acid, (1-butylhexyl)(1-propylpentyl)phosphinic acid, (1-methylheptyl)(1-heptylnonyl)phosphinic acid, (1-butylhexyl)(1-propylpentyl)phosphinic acid, (1-butylhexyl)(1-heptylnonyl)phosphinic acid or (1-propylpentyl)(1-heptylnonyl), more preferably di(1-methylheptyl)phosphinic acid.

[0036] In the present invention, the dialkylphosphinic acid compound having the structure shown in formula B preferably includes di(1,2-dimethylpentyl)phosphinic acid, di(1,2-diethylbutyl)phosphinic acid or (1,2-dimethylpentyl)(1,2-diethylbutyl)phosphinic acid, more preferably di(1,2-diethylbutyl)phosphinic acid.

[0037] In the present invention, the dialkyl phosphinic acid compound having the structure shown in formula C preferably includes (1-methylheptyl)(2-isopropylhexyl)phosphinic acid, (1-butylhexyl)(2-isopropylhexyl)phosphinic acid, (1-propylpentyl)(2-isopropylhexyl)phosphinic acid, (1-heptylnonyl)(2-isopropylhexyl)phosphinic acid, (1-methylheptyl)(2-ethylhexyl)phosphinic acid, (1-butylhexyl)(2-ethylhexyl)phosphinic acid, (1-propylpentyl)(2-isopropylhexyl)phosphinic acid, The phosphinic acid may be any of the following: (1-propylpentyl) (2-ethylhexyl) phosphinic acid, (1-heptylnonyl) (2-ethylhexyl) phosphinic acid, (1-methylheptyl) (2,4,4-trimethylpentyl) phosphinic acid, (1-butylhexyl) (2,4,4-trimethylpentyl) phosphinic acid, (1-propylpentyl) (2,4,4-trimethylpentyl) phosphinic acid or (1-heptylnonyl) (2,4,4-trimethylpentyl) phosphinic acid, more preferably (1-propylpentyl) (2-ethylhexyl) phosphinic acid.

[0038] In the present invention, the dialkyl phosphinic acid compound having the structure shown in formula D preferably includes (1,2-dimethylpentyl) (1-methylheptyl) phosphinic acid, (1,2-diethylbutyl) (1-methylheptyl) phosphinic acid, (1,2-dimethylpentyl) (1-butylhexyl) phosphinic acid, (1,2-diethylbutyl) (1-butylhexyl) phosphinic acid, (1,2-dimethylpentyl) (1-propylpentyl) phosphinic acid, (1,2-diethylbutyl) (1-propylpentyl) phosphinic acid, (1,2-dimethylpentyl) (1-heptylnonyl) phosphinic acid or (1,2-diethylbutyl) (1-heptylnonyl) phosphinic acid, more preferably (1,2-diethylbutyl) (1-heptylnonyl) phosphinic acid.

[0039] In the present invention, the dialkyl phosphinic acid compound having the structure shown in Formula E preferably includes (1,2-dimethylpentyl) (2-ethylhexyl) phosphinic acid, (1,2-diethylbutyl) (2-ethylhexyl) phosphinic acid, (1,2-dimethylpentyl) (2-isopropylhexyl) phosphinic acid, (1,2-dimethylpentyl) (2,4,4-trimethylpentyl) phosphinic acid or (1,2-diethylbutyl) (2,4,4-trimethylpentyl) phosphinic acid, more preferably (1,2-dimethylpentyl) (2,4,4-trimethylpentyl) phosphinic acid.

[0040] The present invention also provides a method for preparing the dialkylphosphinic acid compound described in the above technical solution, comprising the following steps:

[0041] When R1 is the same as R2, R3 is the same as R4, and R5 is the same as R6, the preparation method of the dialkylphosphinic acid compound comprises the following steps;

[0042] Mixing hypophosphorous acid, compound 1 and a first initiator to perform a first addition reaction to obtain the dialkyl phosphinic acid compound;

[0043] When R1 and R2 are different, R3 and R4 are different, or R5 and R6 are different, the preparation method of the dialkylphosphinic acid compound comprises the following steps;

[0044] The hypophosphorous acid, compound 1 and a second initiator are mixed to carry out a second addition reaction to obtain a monoalkyl phosphinic acid compound;

[0045] The monoalkyl phosphinic acid compound, compound 2 and a third initiator are mixed to perform a third addition reaction to obtain the dialkyl phosphinic acid compound;

[0046]

[0047] In the present invention, when R1 is the same as R2, R3 is the same as R4, and R5 is the same as R6, the preparation method of the dialkylphosphinic acid compound comprises the following steps:

[0048] Hypophosphorous acid, compound 1 and a first initiator are mixed to perform a first addition reaction to obtain the dialkylphosphinic acid compound. In the present invention, the first initiator is preferably di-tert-butyl peroxide. In the present invention, the molar ratio of the hypophosphorous acid to compound 1 is preferably 1:2 to 5, more preferably 1:2.5 to 3. In the present invention, the mass ratio of the hypophosphorous acid to the first initiator is preferably 2 to 10:1, more preferably 3 to 5:1.

[0049] In the present invention, the mixing preferably includes the following steps: after the hypophosphorous acid, compound 1 and part of the first initiator are mixed for the first time, the remaining first initiator is added during the first addition reaction. In the present invention, the number of additions is preferably 2 to 4 times, more preferably 3 times; the interval between adjacent additions is preferably 7 to 9 hours, more preferably 8 hours. The present invention adopts the method of adding the first initiator during the first addition reaction to facilitate the completion of the first addition reaction.

[0050] In the present invention, the temperature of the first addition reaction is preferably 130-140°C, more preferably 135°C; the time of the first addition reaction is preferably 25-35h, more preferably 30-32h. In the present invention, the first addition reaction is preferably carried out in a closed reactor with a polytetrafluoroethylene liner.

[0051] In the present invention, after the first addition reaction, the method preferably further comprises: subjecting the system after the first addition reaction to a first water wash, a first alkali wash, a first acidification, a second water wash, water removal and a first concentration in sequence to obtain the dialkylphosphinic acid compound. In the present invention, the water used for the first water wash is preferably deionized water; the number of the first water wash is preferably 2 to 4 times, more preferably 3 times. The present invention removes water-soluble impurities by the first water wash.

[0052] In the present invention, the first alkali washing solvent is preferably a sodium hydroxide solution, and the molar concentration of the sodium hydroxide solution is preferably 0.8 to 1.2 mol / L, more preferably 1 mol / L; the number of the first alkali washing is preferably 2 to 4 times, more preferably 3 times. The present invention utilizes alkali washing to react monoalkyl phosphinic acid with sodium hydroxide to form sodium monoalkyl phosphinate, and utilizes the high water solubility of sodium monoalkyl phosphinate to remove the monoalkyl phosphinic acid.

[0053] In the present invention, the first acidification solvent is preferably a sulfuric acid solution, and the molar concentration of the sulfuric acid solution is preferably 1.8 to 2.2 mol / L, more preferably 2 mol / L. In the present invention, the pH value of the system after the first acidification is preferably 2.0 to 3.0. In the present invention, the dialkyl sodium hypophosphite generated in the first alkaline washing process is converted into dialkyl phosphinic acid by the first acidification.

[0054] In the present invention, the second water washing water is preferably deionized water. The present invention has no particular limitation on the number of times of the second water washing as long as the pH value of the washing liquid after the second water washing is neutral.

[0055] In the present invention, the organic phase after the second water washing is preferably mixed with anhydrous magnesium sulfate to remove water.

[0056] In the present invention, the first concentration is preferably vacuum distillation, the temperature of the vacuum distillation is preferably 80-100° C., more preferably 80-90° C.; the time of the vacuum distillation is preferably 0.5 h to 3 h, more preferably 1 h to 2 h.

[0057] In the present invention, when R1 and R2 are different, R3 and R4 are different, or R5 and R6 are different, the preparation method of the dialkylphosphinic acid compound comprises the following steps:

[0058] The hypophosphorous acid, compound 1 and a second initiator are mixed to carry out a second addition reaction to obtain a monoalkyl phosphinic acid compound;

[0059] The monoalkyl phosphinic acid compound, compound 2 and a third initiator are mixed to carry out a third addition reaction to obtain the dialkyl phosphinic acid compound.

[0060] The present invention mixes hypophosphorous acid, compound 1 and a second initiator to carry out a second addition reaction to obtain a monoalkyl phosphinic acid compound. In the present invention, the second initiator is preferably di-tert-butyl peroxide. In the present invention, the molar ratio of the hypophosphorous acid and compound 1 is preferably 1.5 to 4:1, and more preferably 2 to 3:1. In the present invention, the mass ratio of the hypophosphorous acid and the second initiator is preferably 20 to 60:1, and more preferably 35 to 45:1. In the present invention, the temperature of the second addition reaction is preferably 130 to 140°C, and more preferably 135°C; the time of the second addition reaction is preferably 7 to 9h, and more preferably 8h. In the present invention, the second addition reaction is preferably carried out in a closed reactor with a polytetrafluoroethylene liner.

[0061] In the present invention, after the second addition reaction, the method preferably further comprises: subjecting the system after the second addition reaction to a third water wash, extraction, second acidification, and second concentration of the organic phase after the second acidification to obtain the monoalkylphosphinic acid compound. In the present invention, the water used for the third water wash is preferably deionized water; the present invention has no particular limitation on the number of times of the third water wash, as long as the pH value of the washing liquid after the third water wash is neutral. In the present invention, the organic phase after the third water wash is subjected to extraction.

[0062] In the present invention, the extraction agent is preferably a mixture of petroleum ether and sodium hydroxide solution. In the present invention, the mass concentration of the sodium hydroxide solution is preferably 8-12%, more preferably 10%. In the present invention, the volume ratio of the petroleum ether to the sodium hydroxide solution is preferably 1.5-2.5:1, more preferably 2:1. The present invention is divided into three phases of upper, middle and lower through the extraction system, and the middle organic phase and the lower aqueous phase are collected for the second acidification.

[0063] In the present invention, the second acidification solvent is preferably a mixture of petroleum ether and sulfuric acid solution. In the present invention, the molar concentration of the sulfuric acid solution is preferably 2.5-3.5 mol / L, more preferably 3 mol / L. In the present invention, the volume ratio of the petroleum ether to the sulfuric acid solution is preferably 3:1-1:3, more preferably 1:2. In the present invention, the pH value of the aqueous phase after the second acidification is preferably 2.0-3.0. In the present invention, the organic phase after the second acidification is subjected to a second concentration.

[0064] In the present invention, the second concentration is preferably vacuum distillation. The present invention has no particular limitation on the vacuum distillation, as long as the petroleum ether can be removed.

[0065] After obtaining the monoalkyl phosphinic acid compound, the present invention mixes the monoalkyl phosphinic acid compound, compound 2 and a third initiator to perform a third addition reaction to obtain the dialkyl phosphinic acid compound. In the present invention, the third initiator is preferably di-tert-butyl peroxide. In the present invention, the molar ratio of the monoalkyl phosphinic acid compound to compound 2 is preferably 1:1.4 to 2, and more preferably 1:1.5. In the present invention, the mass ratio of the monoalkyl phosphinic acid compound to the third initiator is preferably 8 to 10:1.2, and more preferably 8.9 to 9:1.2.

[0066] In the present invention, the mixing preferably includes the following steps: after the monoalkylphosphinic acid compound, compound 2 and part of the third initiator are mixed for the second time, the remaining third initiator is added during the third addition reaction. In the present invention, the number of additions is preferably 2 to 4 times, more preferably 2 times; the interval between adjacent additions is preferably 9 to 11 hours, more preferably 10 hours. The present invention adopts the method of adding the third initiator during the third addition reaction to facilitate the completion of the third addition reaction.

[0067] In the present invention, the temperature of the third addition reaction is preferably 130-140°C, more preferably 135°C; the time of the third addition reaction is preferably 25-35h, more preferably 30-32h. In the present invention, the third addition reaction is preferably carried out in a closed reactor with a polytetrafluoroethylene liner.

[0068] In the present invention, after the third addition reaction, the method preferably further comprises: subjecting the system after the third addition reaction to a fourth water wash, a second alkali wash, a third acidification, a fifth water wash and a third concentration in sequence to obtain the dialkylphosphinic acid compound. In the present invention, the water used for the fourth water wash is preferably deionized water; the number of the fourth water wash is preferably 2 to 4 times, more preferably 3 times. The present invention removes water-soluble impurities in the system through the fourth water wash.

[0069] In the present invention, the second alkali washing solvent is preferably a sodium hydroxide solution, and the molar concentration of the sodium hydroxide solution is preferably 0.8 to 1.2 mol / L, more preferably 1 mol / L; the number of the second alkali washing is preferably 2 to 4 times, more preferably 3 times. In the present invention, the generated monoalkyl phosphinic acid is reacted with sodium hydroxide to form sodium monoalkyl phosphinate by alkali washing, and the monoalkyl phosphinic acid is removed by utilizing the high water solubility of sodium monoalkyl phosphinate.

[0070] In the present invention, the third acidification solvent is preferably a sulfuric acid solution, and the molar concentration of the sulfuric acid solution is preferably 1.8 to 2.2 mol / L, more preferably 2 mol / L. In the present invention, the pH value of the aqueous phase after the third acidification is preferably 2.0 to 3.0. The present invention converts the dialkyl sodium hypophosphite generated in the second alkaline washing process into dialkyl phosphinic acid through the third acidification.

[0071] In the present invention, the water used for the fifth water washing is preferably deionized water. The present invention has no particular limitation on the number of times of the fifth water washing as long as the pH value of the washing liquid after the fifth water washing is neutral. In the present invention, after the fifth water washing, the organic phase after the fifth water washing is preferably mixed with anhydrous magnesium sulfate for dehydration.

[0072] In the present invention, the third concentration is preferably vacuum distillation, the temperature of the vacuum distillation is preferably 80-90°C, more preferably 83-85°C; the time of the vacuum distillation is preferably 1h-3h, more preferably 2h.

[0073] In the present invention, the extractant is preferably a hydrometallurgical extractant. In the present invention, the dialkylphosphinic acid compound is used as a hydrometallurgical extractant for extraction at room temperature, which is preferably 15 to 30°C, more preferably 20 to 25°C.

[0074] The method of extracting a solution containing metal ions using a dialkylphosphinic acid compound as an extractant of the present invention preferably comprises the following steps:

[0075] mixing the extractant and the diluent to obtain an extracted organic phase;

[0076] The extracted organic phase and the alkaline solution are mixed for saponification reaction, and then mixed with the liquid to be extracted for multi-stage countercurrent extraction to obtain an organic phase;

[0077] The organic phase is subjected to acid stripping to obtain an aqueous solution of extracted metal ions.

[0078] The present invention mixes an extractant and a diluent to obtain an extracted organic phase. In the present invention, the extractant preferably includes any one structure or multiple structures of the dialkylphosphinic acid compounds described in the above technical solution. In the present invention, the diluent is preferably an alkane-based inert solvent oil, and the alkane-based inert solvent oil is preferably Exxsol D110 solvent oil, 260# solvent oil, sulfonated kerosene or light white oil, more preferably 260# solvent oil or Exxsol D110 solvent oil. In the present invention, the extracted organic phase preferably also includes a synergist, and the synergist preferably includes a phosphate (phosphonate) ester compound, a long-chain phenol compound or a long-chain alcohol compound, more preferably tributyl phosphate, trialkylphosphine oxide, nonylphenol, dodecylphenol, isooctyl alcohol, sec-octanol, propylheptyl alcohol or isotridecanol.

[0079] In the present invention, the volume percentage of the extractant in the extracted organic phase is preferably 5-50%, more preferably 10-40%, and further preferably 15-20%.

[0080] The present invention has no special requirements for the mixing, as long as the mixing can be uniform.

[0081] After obtaining the extracted organic phase, the present invention mixes the extracted organic phase with an alkaline solution for saponification reaction and then mixes it with the extract to be extracted for multi-stage countercurrent extraction to obtain an organic phase. In the present invention, the alkaline solution preferably includes sodium hydroxide solution or ammonia water, more preferably sodium hydroxide solution. In the present invention, the mass concentration of the alkaline solution is preferably 28-32%, more preferably 30%. In the present invention, the saponification rate of the saponification reaction is preferably 10-60%, more preferably 25-40%, and further preferably 30-35%.

[0082] In the present invention, the metal ions contained in the extracted solution preferably include any two or more of nickel ions, cobalt ions, manganese ions, calcium ions and magnesium ions. In the present invention, the extracted solution is preferably the acid-dissolved solution after nickel and cobalt precipitation in laterite nickel ore, a high-concentration nickel sulfate solution containing a certain amount of cobalt sulfate, a solution in a certain process section of the positive electrode material recovery of retired lithium-ion batteries, or a solution after acid leaching and impurity removal of manganese ore.

[0083] In the present invention, the temperature of the multi-stage countercurrent extraction is preferably room temperature, and the room temperature is preferably 15 to 30° C., more preferably 20 to 25° C. In the present invention, the volume ratio (O / A) of the organic phase to the aqueous phase of the multi-stage countercurrent extraction is preferably 0.2 to 5:1, more preferably 0.5 to 1.5:1, and further preferably 0.8 to 1:1. In the present invention, the number of stages of the multi-stage countercurrent extraction is preferably 3 to 5, more preferably 4.

[0084] After obtaining the organic phase, the present invention performs acid stripping on the organic phase to obtain an aqueous solution of extracted metal ions. In the present invention, the solvent for acid washing is preferably an acid solution, and the acid solution is preferably a sulfuric acid solution or a hydrochloric acid solution, more preferably a sulfuric acid solution; the mass concentration of the acid solution is preferably 10 to 20 g / L, more preferably 15 g / L. In the present invention, the volume ratio of the organic phase and the aqueous phase of the acid washing is preferably 5 to 40:1, more preferably 10 to 15:1. In the present invention, the acid washing is preferably multi-stage countercurrent washing, and the number of stages of the multi-stage countercurrent washing is preferably 2 to 4, more preferably 3.

[0085] In the present invention, the stripping solvent is preferably an acid solution, and the acid solution preferably includes a hydrochloric acid solution or a sulfuric acid solution, more preferably a sulfuric acid solution; the mass concentration of the acid solution is preferably 200-300 g / L. In the present invention, the volume ratio of the organic phase and the aqueous phase of the stripping is preferably 2-40:1, more preferably 5-20:1, and further preferably 10-15:1. In the present invention, the stripping is preferably a multi-stage countercurrent stripping, and the number of stages of the multi-stage countercurrent stripping is preferably 2-3. The present invention preferably repeatedly recycles the blank organic phase after stripping.

[0086] The high steric hindrance dialkyl phosphinic acid extractant provided by the present invention can extract and separate cobalt, magnesium and manganese from a solution containing nickel, cobalt, magnesium and manganese. The source and specific type of the solution containing nickel, cobalt, magnesium and manganese are not limited. For example, it can be any one of nickel laterite leaching solution, waste lithium ion battery positive and negative electrode material leaching solution, electroplating waste liquid or nickel sulfide ore leaching solution, or other slurry containing nickel, cobalt, magnesium and manganese. The high steric hindrance dialkyl phosphinic acid extractant provided by the present invention can extract all manganese from a solution containing manganese, calcium and magnesium into an organic phase, while leaving calcium and magnesium in an aqueous phase, thereby achieving the purpose of manganese / calcium and manganese / magnesium separation, and preparing a high-purity manganese compound. The source and specific type of the solution containing manganese, calcium and magnesium are not limited. For example, manganese ore leaching impurity removal liquid, waste lithium ion battery positive and negative electrode material leaching solution, or other slurry containing manganese, calcium and magnesium.

[0087] The high steric hindrance dialkylphosphinic acid extractant provided by the present invention effectively solves the problems of high water solubility, difficult phase separation, easy emulsification, low capacity, and heating required during the extraction process of the C272 extraction system. The extractant can replace all application scenarios of C272 and overcome the inherent defects of the 272 extractant. The extractant provided by the present invention can replace C272 for nickel laterite ore, ternary lithium battery recovery, nickel / cobalt separation, nickel / magnesium separation, manganese / calcium and manganese / magnesium separation in the production process of high-purity manganese, etc., greatly simplifying the extraction process, reducing reagent consumption, reducing equipment investment, reducing energy consumption, and reducing production costs.

[0088] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0089] Example 1

[0090] 7.76 g (0.1 mol) of 85% hypophosphorous acid solution, 29 g (0.26 mol) of 2-octene, and 0.63 g of di-tert-butyl peroxide were placed in a 50 mL closed reactor lined with polytetrafluoroethylene, and subjected to addition reaction at 135° C. for 32 h, with 0.37 g of di-tert-butyl peroxide added once every 8 h for three times; after the addition reaction, the reaction system was transferred to a separatory funnel, washed with deionized water for 3 times (30 mL×3), then washed with 10 mL of 1 mol / L NaOH solution for 3 times, then acidified with 2 mol / L H2SO4 solution to a pH value of 2.5 for the aqueous phase, and finally washed with deionized water to a pH value of neutral for the aqueous phase, the washed organic phase was mixed with anhydrous MgSO4 to remove water, and then subjected to reduced pressure distillation at 85° C. for 1 h to obtain 23.8 g of di(1-methylheptyl)phosphinic acid, the structural formula of which is The NMR characterization data of the product are as follows:

[0091] 1 H-NMR (CDCl3, 600MHz): δ12.35 (s, 1H), δ1.68 (m, 2H), δ1.29-1.33 (m, 20H), δ0.92-1.06 (m, 12H).

[0092] 13 C-NMR (CDCl3, 600MHz): δ39.67, 35.95, 33.57, 32.46, 30.72, 27.01, 19.26, 16.89.

[0093] 31 P-NMR (CDCl3, 600MHz): δ64.75.

[0094] The acid-dissolved feed liquid after nickel and cobalt precipitation from laterite nickel ore was treated with P204 to remove impurities as the extraction liquid, which was recorded as L1. The prepared di(1-methylheptyl)phosphinic acid was used as an extractant to extract and separate cobalt, manganese and magnesium from L1, to achieve nickel / cobalt, nickel / manganese and nickel / magnesium separation, to obtain a high-purity nickel solution, and then further recover the valuable metal cobalt.

[0095] Extraction conditions: room temperature (20°C); 260# solvent oil as diluent, extractant concentration (v / v) is 20%; saponification with 32% sodium hydroxide solution, saponification rate 35%; extraction O / A is 1:1; 20g / L sulfuric acid is used as detergent, washing O / A is 10:1; 300g / L sulfuric acid is used as stripping agent, stripping O / A is 10:1.

[0096] Results: The operation was very smooth at room temperature (20°C), and the phase separation was very good throughout the process. After 4-stage extraction, 2-stage washing, and 3-stage stripping, the Co, Mg, and Mn in the pre-extraction solution were removed to below 0.01 g / L to obtain a high-purity nickel solution. The Co, Mg, and Mn in the stripping solution were enriched for subsequent further separation and recovery. The specific data are shown in Table 1.

[0097] Table 1 Extraction test results of di(1-methylheptyl)phosphinic acid on L1

[0098]

[0099] Example 2

[0100] Di(1,2-diethylbutyl)phosphinic acid was prepared according to the method of Example 1, except that 2-octene was replaced by 3-ethyl-3-hexene. The structural formula of di(1,2-diethylbutyl)phosphinic acid is

[0101]

[0102] The NMR characterization data of di(1,2-diethylbutyl)phosphinic acid are as follows:

[0103] 1 H-NMR (CDCl3, 600MHz): δ11.68 (s, 1H), δ1.75 (m, 4H), δ1.26-1.34 (m, 12H), δ0.95-1.08 (m, 18H).

[0104] 13 C-NMR (CDCl3, 600MHz): δ49.6, 32.96, 26.86, 25.85, 15.37, 13.26.

[0105] 31 P-NMR (CDCl3, 600MHz): δ 64.49

[0106] In this embodiment, the pre-extraction feed liquid is a feed liquid of a certain process section of the recycling of retired lithium-ion battery positive electrode materials, which is recorded as L2. The prepared di(1,2-diethylbutyl)phosphinic acid is used as an extractant to extract and separate cobalt and magnesium from L2, thereby achieving the separation of nickel / cobalt and nickel / magnesium, and obtaining a high-purity nickel sulfate solution, and then further recovering cobalt.

[0107] Extraction conditions: room temperature (20°C); Exxsol D110 solvent oil as diluent, extractant concentration (v / v) of 15%; saponification with 32% liquid alkali, saponification rate of 30%; extraction O / A of 0.8:1; 15g / L sulfuric acid as detergent, washing O / A of 15:1; 200g / L sulfuric acid as stripping agent, stripping O / A of 20:1.

[0108] Results: The operation was very smooth at room temperature (20°C), and no heating or insulation was required. The phase separation was very good during the whole process. After 4-stage extraction, 3-stage washing, and 3-stage stripping, the Co and Mg in the pre-extraction solution were reduced to below 0.01 g / L to obtain a high-purity nickel solution, and the valuable metal cobalt was further recovered later. The specific data are shown in Table 2.

[0109] Table 2 Extraction test results of di(1,2-diethylbutyl)phosphinic acid on L2

[0110]

[0111] Example 3

[0112] 23.3 g (0.3 mol) of 85% hypophosphorous acid solution, 11.2 g (0.1 mol) of 4-octene, and 0.55 g of di-tert-butyl peroxide were placed in a 50 mL closed reactor lined with polytetrafluoroethylene, and subjected to addition reaction at 135°C for 8 h. The mixture was transferred to a separatory funnel, and the organic phase was washed with deionized water until the pH value of the aqueous phase was neutral. The aqueous phase was discarded. 20 mL of petroleum ether and 40 mL of 10% NaOH solution were added to the washed organic phase. , fully mixed, after standing, the system is divided into three phases, the middle organic phase and the lower aqueous phase are collected, and transferred to another separatory funnel, 10mL of petroleum ether and 20mL of 3mol / L sulfuric acid solution (the volume ratio of petroleum ether to sulfuric acid solution is 1:2) are added to the separatory funnel until the pH value of the aqueous phase is about 2.5, the system is divided into two phases, and the aqueous phase is discarded; the upper organic phase is distilled under reduced pressure at 85°C for 2h to remove petroleum ether to obtain 1-propylpentylphosphinic acid (15.6g);

[0113] 8.9 g (0.05 mol) of 1-propylpentylphosphinic acid, 8.4 g (0.075 mol) of 2-ethyl-1-hexene, and 0.4 g of di-tert-butyl peroxide were added to a 50 mL closed reactor lined with polytetrafluoroethylene, placed in a homogeneous reactor, and subjected to addition reaction at 135°C for 30 h, during which 0.4 g of di-tert-butyl peroxide was added every 10 h for 2 times; after the addition reaction, the product was transferred to a separatory funnel and washed with deionized water for 3 times (30 m L×3), then washed three times with 10mL of 1mol / L NaOH solution, then acidified with 10mL of 2mol / L H2SO4 solution to a pH value of about 2.5, and finally washed with deionized water to a neutral pH value of the aqueous phase. The organic phase after washing was mixed with anhydrous MgSO4 and dehydrated, and then distilled under reduced pressure at 85°C for 2h to obtain 13.8g of the product (1-propylpentyl) (2-ethylhexyl) phosphinic acid, with the structural formula

[0114] The NMR characterization data of the product are as follows:

[0115] 1 H-NMR (CDCl3, 600MHz): δ11.95 (s, 1H), δ1.56 (m, 2H), δ1.46 (d, 2H), δ1.25-1.33 (m, 18H), δ0.93-1.07 (m, 12H).

[0116] 13C-NMR (CDCl3, 600MHz): δ38.6, 38.15, 36.33, 33.95, 34.13, 33.29, 32.99, 32.65, 29.45, 26.50, 25.91, 24.75, 17.78, 14.56.

[0117] 31 P-NMR (CDCl3, 600MHz): δ62.56.

[0118] The pre-extraction liquid in this embodiment is the same as the pre-extraction liquid in Example 2. The prepared (1-propylpentyl) (2-ethylhexyl) phosphinic acid is used as an extractant to extract and separate cobalt and magnesium from L2, thereby achieving separation of nickel / cobalt and nickel / magnesium, and obtaining a high-purity nickel sulfate solution, which is then used to recover the valuable metal cobalt.

[0119] Extraction conditions: room temperature (15°C); Exxsol D110 solvent oil as diluent, extractant concentration (v / v) of 15%; saponification with 32% liquid alkali, saponification rate of 40%; extraction O / A of 1:1; 10 g / L sulfuric acid as detergent, washing O / A of 10:1; 200 g / L sulfuric acid as stripping agent, stripping O / A of 20:1.

[0120] Results: The operation was very smooth at room temperature (15°C), and no heating or insulation was required. The phase separation was very good during the whole process. After 3-stage extraction, 2-stage washing, and 3-stage stripping, the Co and Mg in the pre-extraction solution were reduced to below 0.01 g / L to obtain a high-purity nickel solution. The specific data are shown in Table 3.

[0121] Table 3 Extraction test results of L2 by (1-propylpentyl) (2-ethylhexyl) phosphinic acid

[0122]

[0123] Example 4

[0124] (1,2-diethylbutyl)(1-heptylnonyl)phosphinic acid was prepared according to the method of Example 3, except that 4-octene was replaced by 7-hexadecene, and 2-ethyl-1-hexene was replaced by 4-ethyl-3-hexene;

[0125] The structural formula of (1,2-diethylbutyl)(1-heptylnonyl)phosphinic acid is

[0126]

[0127] The NMR characterization data of the product are as follows:

[0128] 1H-NMR (CDCl3, 600MHz): δ11.56 (s, 1H), δ1.53 (m, 3H), δ1.0-1.35 (m, 32H), δ0.95-1.05 (m, 15H).

[0129] 13 C-NMR (CDCl3, 600MHz): δ 53.89, 37.61, 36.92, 35.25, 33.73, 32.89, 32.53, 31.92, 31.05, 30.54, 26.01, 18.25, 17.36, 15.24.

[0130] 31 P-NMR (CDCl3, 600MHz): δ65.67.

[0131] In this embodiment, the feed liquid before extraction is the feed liquid after the manganese ore is acid-leached and impurities are removed, which is recorded as L3. (1,2-diethylbutyl)(1-heptylnonyl)phosphinic acid is used as an extractant to extract the main element manganese from L3 into the organic phase, and the impurity elements magnesium and calcium are left in the raffinate, thereby achieving the separation of manganese / calcium and manganese / magnesium to obtain a high-purity manganese solution.

[0132] Extraction conditions: room temperature (25°C); Exxsol D110 solvent oil as diluent, extractant concentration (v / v) is 40%; extraction O / A is 1.5:1; saponification with 30% liquid alkali, saponification rate is 60%; 10 g / L sulfuric acid is used as detergent, washing O / A is 15:1; 300 g / L sulfuric acid is used as stripping agent, stripping O / A is 5:1.

[0133] Results: The operation was very smooth at room temperature (25°C), and no heating or insulation was required. All processes had good phase separation. After 5-stage extraction, 4-stage washing, and 4-stage stripping, the manganese extraction rate reached 99.1%, and Mg and Ca remained in the raffinate and the washing liquid. The Mn concentration in the stripping liquid reached 101.8 g / L, and the purity reached 99.99%, achieving deep separation of Mn from Ca and Mg. The specific data are shown in Table 4.

[0134] Table 4 Extraction test results of L3 by (1,2-diethylbutyl) (1-heptylnonyl) phosphinic acid

[0135]

[0136] Example 5

[0137] (1,2-dimethylpentyl)(2,4,4-trimethylpentyl)phosphinic acid was prepared according to the method of Example 3, except that 4-octene was replaced by 3-methyl-2-hexene, and 2-ethyl-1-hexene was replaced by diisobutylene; the structural formula of (1,2-dimethylpentyl)(2,4,4-trimethylpentyl)phosphinic acid is

[0138]

[0139] The NMR characterization data of the product are as follows:

[0140] 1 H-NMR (CDCl3, 600MHz): δ12.13 (s, 1H), δ1.58-1.72 (m, 3H), δ1.45 (d, 2H), δ1.15-1.35 (m, 6H), δ0.92-1.07 (m, 21H).

[0141] 13 C-NMR (CDCl3, 600MHz): δ54.65, 40.39, 37.03, 35.86, 34.79, 32.92, 32.32, 24.93, 22.51, 21.94, 18.08, 17.71, 13.15.

[0142] 31 P-NMR (CDCl3, 600MHz): δ62.82.

[0143] The pre-extraction feed liquid of this embodiment is the same as the pre-extraction liquid of Example 4. The prepared (1,2-dimethylpentyl) (2,4,4-trimethylpentyl) phosphinic acid is used as the extractant to extract the main element manganese from L3 into the organic phase, and the impurity elements magnesium and calcium are left in the raffinate to achieve the separation of manganese / calcium and manganese / magnesium, and obtain a high-purity manganese solution.

[0144] Extraction conditions: room temperature (20°C); 260# solvent oil is used as the diluent, and the extractant concentration (v / v) is 35%; the extraction O / A is 2:1; 30% liquid alkali is used for saponification, and the saponification rate is 60%; 10g / L sulfuric acid is used as the detergent, and the washing O / A is 20:1; 250g / L sulfuric acid is used as the stripping agent, and the stripping O / A is 8:1.

[0145] Results: The operation was very smooth at room temperature (20°C), and no heating or insulation was required. All processes had good phase separation. After 5-stage extraction, 4-stage washing, and 4-stage stripping, the manganese extraction rate reached 99.0%, and Mg and Ca remained in the raffinate and the washing liquid. The Mn concentration in the stripping liquid reached 101.8 g / L, and the purity reached 99.99%, achieving deep separation of Mn from Ca and Mg. The specific data are shown in Table 5.

[0146] Table 5 Extraction test results of L3 by (1,2-dimethylpentyl) (2,4,4-trimethylpentyl) phosphonic acid

[0147]

[0148] Comparative Example 1

[0149] The structural formula purchased from Solvay China Ltd. C272 was used as the extractant.

[0150] The pre-extraction liquid of this comparative example is the same as the pre-extraction liquid of Example 1. The extraction was carried out under the same conditions as Example 1. The results showed that the saponification and extraction processes were obviously emulsified, the organic phase had poor fluidity, and the entire extraction and separation process could not be carried out;

[0151] Under the same conditions as in Example 1, the temperature of the saponification and extraction system was heated to 40°C, the fluidity of the organic phase was significantly improved, and the emulsification completely disappeared. Under these conditions, after 4-stage extraction, 2-stage washing, and 3-stage stripping, the Co, Mg, and Mn in the pre-extraction solution were removed to less than 0.01 g / L to obtain a high-purity nickel solution, and the Co, Mg, and Mn in the stripping solution were enriched for subsequent further separation and recovery. The specific data are shown in Table 6.

[0152] Table 6 Extraction test results of C272 on L1

[0153]

[0154] Comparative Example 2

[0155] C272 was used as the extractant, and the pre-extraction liquid of Example 2 was used as the pre-extraction liquid. The extraction was carried out under the same conditions as Example 2. The results showed that the saponification and extraction processes were obviously emulsified, and the entire extraction and separation process could not be carried out;

[0156] Under the same conditions as in Example 2, the temperature of the saponification and extraction system was raised to 45°C, the fluidity of the organic phase was good, and the emulsification disappeared completely. Under these conditions, after 4-stage extraction, 3-stage washing, and 3-stage stripping, the Co and Mg in the pre-extraction solution were reduced to less than 0.01 g / L to obtain a high-purity nickel solution, and the valuable metal cobalt was subsequently recovered. The specific data are shown in Table 7.

[0157] Table 7 Extraction test results of C272 on L2

[0158]

[0159] Comparative Example 3

[0160] C272 was used as the extractant, and the pre-extraction liquid of Example 4 was used as the pre-extraction liquid. The extraction was carried out under the same conditions as Example 4. The results showed that the saponification and extraction processes were obviously emulsified, and the entire extraction and separation process could not be carried out;

[0161] Under the same other conditions as in Example 4, the temperature of the saponification and extraction system was raised to 40°C, but the emulsification of the organic phase was still not eliminated;

[0162] Under the condition of saponification and extraction temperature of 40°C, the saponification rate of the extractant was reduced to 40%, and other conditions were the same as those in Example 4. The emulsification of the organic phase was significantly improved, the emulsification basically disappeared, and the fluidity became better. Under these conditions, after 9 levels of extraction, 5 levels of washing, and 4 levels of stripping, the impurity elements magnesium and calcium were left in the raffinate, and the separation of manganese / calcium-based manganese / magnesium was achieved to obtain a high-purity manganese solution. The specific data are shown in Table 8.

[0163] Table 8 Extraction test results of C272 on L3

[0164]

[0165] It can be seen from the extraction results of Examples 1 to 5 and Comparative Examples 1 to 3 that the use of the highly hindered dialkylphosphinic acid of the present invention as an extractant at room temperature and a high saponification rate exhibits excellent phase separation performance, and the separation performance of metal ions is not lower than that of C272, while C272 is very easy to emulsify at room temperature and a high saponification rate, has poor fluidity, and must be used above 40° C. Therefore, the extractant of the present invention can reduce energy consumption, reduce the amount of extractant used, and reduce equipment investment during application, and has good economic and environmental benefits.

[0166] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A use of a dialkylphosphinic acid compound as an extractant, characterized in that: The dialkylphosphinic acid compound has a structure shown in Formula 1: Wherein, R1 to R4 are independently -H or the first alkyl group, and R1 and R2 cannot be -H at the same time; R5 and R6 are independently a second alkyl group; The total number of C atoms in the dialkylphosphinic acid compound is 16-40.

2. The application according to claim 1, characterized in that: The extractant is a hydrometallurgical extractant.

3. The application according to claim 2, characterized in that: The dialkylphosphinic acid compound is used as a hydrometallurgical extractant for extraction at room temperature, which is 15-30°C.

4. The use according to claim 3, characterized in that: The metal ions contained in the extraction solution include any two or more of nickel ions, cobalt ions, manganese ions, calcium ions and magnesium ions.

5. The use according to claim 1, characterized in that: The number of C atoms in the first alkyl group is 1-7.

6. The use according to claim 5, characterized in that: The first alkyl group includes a methyl group, a propyl group, a butyl group, a heptyl group or an isopropyl group.

7. The use according to claim 1, characterized in that: The second alkyl group includes butyl, pentyl, hexyl, heptyl or nonyl.

8. The use according to claim 1, 5, 6 or 7, characterized in that: The dialkylphosphinic acid compounds include di(1-methylheptyl)phosphinic acid, di(1-butylhexyl)phosphinic acid, di(1-propylpentyl)phosphinic acid, di(1-heptylnonyl)phosphinic acid, (1-methylheptyl)(1-butylhexyl)phosphinic acid, (1-methylheptyl)(1-propylpentyl)phosphinic acid, (1-methylheptyl)(1-heptylnonyl)phosphinic acid, (1-butylhexyl)(1-propylpentyl)phosphinic acid, (1-propylpentyl)(1-heptylnonyl)phosphinic acid, (1-butylhexyl)(1-propylpentyl)phosphinic acid, (1-butylhexyl)(1-heptylnonyl)phosphinic acid, (1-propylpentyl)(1-heptylnonyl), di(1,2-dimethylpentyl)phosphinic acid, di(1, 2-diethylbutyl)phosphinic acid, (1,2-dimethylpentyl) (1,2-diethylbutyl) phosphinic acid, (1-methylheptyl) (2-isopropylhexyl) phosphinic acid, (1-butylhexyl) (2-isopropylhexyl) phosphinic acid, (1-propylpentyl) (2-isopropylhexyl) phosphinic acid, (1-heptylnonyl) (2-isopropylhexyl) phosphinic acid, (1-methylheptyl) (2-ethylhexyl) phosphinic acid, (1-butylhexyl) (2-ethylhexyl) phosphinic acid, (1-propylpentyl) (2-ethylhexyl) phosphinic acid, (1-heptylnonyl) (2-isopropylhexyl) phosphinic acid, (1 -methylheptyl)(2,4,4-trimethylpentyl)phosphinic acid, (1-butylhexyl)(2,4,4-trimethylpentyl)phosphinic acid, (1-propylpentyl)(2,4,4-trimethylpentyl)phosphinic acid, (1-heptylnonyl)(2,4,4-trimethylpentyl)phosphinic acid, (1,2-dimethylpentyl)(1-methylheptyl)phosphinic acid, (1,2-diethylbutyl)(1-methylheptyl)phosphinic acid, (1,2-dimethylpentyl)(1-butylhexyl)phosphinic acid, (1,2-diethylbutyl)(1-butylhexyl)phosphinic acid, (1,2-dimethylpentyl)(1- propylpentyl)phosphinic acid, (1,2-diethylbutyl)(1-propylpentyl)phosphinic acid, (1,2-dimethylpentyl)(1-heptylnonyl)phosphinic acid, (1,2-diethylbutyl)(1-heptylnonyl)phosphinic acid, (1,2-dimethylpentyl)(2-ethylhexyl)phosphinic acid, (1,2-diethylbutyl)(2-ethylhexyl)phosphinic acid, (1,2-dimethylpentyl)(2-isopropylhexyl)phosphinic acid, (1,2-dimethylpentyl)(2,4,4-trimethylpentyl)phosphinic acid or (1,2-diethylbutyl)(2,4,4-trimethylpentyl)phosphinic acid.

9. The use according to claim 1, characterized in that: The preparation method of the dialkylphosphinic acid compound comprises the following steps: When R1 is the same as R2, R3 is the same as R4, and R5 is the same as R6, the preparation method of the dialkylphosphinic acid compound comprises the following steps; Mixing hypophosphorous acid, compound 1 and a first initiator to perform a first addition reaction to obtain the dialkyl phosphinic acid compound; When R1 and R2 are different, R3 and R4 are different, or R5 and R6 are different, the preparation method of the dialkylphosphinic acid compound comprises the following steps; The hypophosphorous acid, compound 1 and a second initiator are mixed to carry out a second addition reaction to obtain a monoalkyl phosphinic acid compound; The monoalkyl phosphinic acid, compound 2 and a third initiator are mixed to perform a third addition reaction to obtain the dialkyl phosphinic acid compound; 10. The use according to claim 9, characterized in that: The temperature of the first addition reaction is 130-140° C. and the time is 25-35 hours; The temperature of the second addition reaction is 130-140° C. and the time is 7-9 hours; The temperature of the third addition reaction is 130-140° C., and the time is 25-35 hours.

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