Method for extracting lithium from salt lake brine with high magnesium to lithium ratio

Abstract

The invention provides a method for extracting lithium from salt lake brine with a high magnesium to lithium ratio. An extracting system comprises an extracting agent, a co-extracting agent and a diluent; the extracting agent is a mixture of sulphonamide compounds and tributyl phosphate; the co-extracting agent is ferric trichloride; the diluent is solvent gasoline or sulfonated kerosene. According to the method, the concentration of the tributyl phosphate is reduced, so that the dissolving amount of brine in the tributyl phosphate is reduced; a water-in-oil phenomenon is improved; the product impurity is improved; during a back-extraction process of the materials, the hydrolysis capacity of the materials is reduced by acidity, so that the loss of an oil phase in repeated extracting processes is reduced, and meanwhile, the lithium extraction yield in the prior art is achieved, operation is easy in the extracting process, and industrial production is facilitated.

Description

technical field

[0001] The invention relates to a method for extracting lithium salt from brine of a high-magnesium-lithium ratio salt lake by using a solvent extraction method. Background technique

[0002] my country is a country with a large amount of lithium resources, and its proven reserves of lithium resources rank second in the world, second only to Bolivia. The salt lake lithium resources in the Qaidam Basin in Qinghai are very rich, ranking first in the country. The main feature of the lithium-rich salt lake in Qinghai is the high content of associated magnesium, and the magnesium / lithium ratio in the brine is as high as 40-1200. Because the chemical properties of magnesium and lithium are very similar, it is very difficult to separate and extract lithium, which has long restricted the development of lithium extraction industry in Qinghai brine.

[0003] Solvent extraction is a lithium extraction technology that has been studied more in China. It has the advantag...

Examples

Embodiment 1

[0019] The extractant is TBP and sulfonamide compound N,N-bis-(2-ethylhexyl)ethylsulfonamide, whose structural formula is as follows:

[0020]

[0021] The synthesis method of the above-mentioned N,N-bis-(2-ethylhexyl)ethylsulfonamide: add 0.3mol of N,N-bis-(2-ethylhexyl)amine into a 1000ml three-necked flask, add 0.33mol of Ethylsulfonyl chloride, 200ml dichloromethane, stir to cool down to -5°C~0°C, add dropwise 0.3mol ethylsulfonyl chloride / 150ml methylene chloride solution, keep the system temperature below 5°C during the dropwise addition, and complete the dropwise addition , react at 0°C for 2h, add 220ml of water, extract and keep the organic phase. The organic phase was washed with alkali and acid respectively, dried with anhydrous sodium sulfate, and spin-dried to obtain the target product.

[0022] Add 1 volume of salt lake brine shown in Table 1 into a separatory funnel, add a certain amount of FeCl 3 (FeCl 3 Li in brine + The molar ratio is 1:1) as a co-extr...

Embodiment 2

[0026] The extractant is TBP and sulfonamide compound N-methyl-N-phenylethyl ethyl sulfonamide, and its structural formula is as follows:

[0027]

[0028] Add 1 volume of salt lake brine shown in Table 1 into a separatory funnel, add a certain amount of FeCl 3 (FeCl 3 Li in brine + The molar ratio is 1:1.5) as a co-extraction agent, shake to dissolve it. Add 5 volumes of the organic phase (compared to O / A=5), wherein the volume ratio of N-methyl-N-phenylethylethylsulfonamide, TBP and 200# solvent naphtha is 4:3:3, shake for 10 After 10 minutes rest layered. Determination of Li in the equilibrium aqueous phase + , Calculate the extraction rate of lithium to be 90.96%. After washing, stripping, evaporation, decolorization, cooling, crystallization and drying, the Na in the product is measured + 、K + , Mg 2+ , Ca 2+ , SO 4 2- , B 2 o 3 The percentage contents are 0.0030%, 0.0008%, 0.0016%, 0.0005%, 0.0012%, 0.028%, respectively.

Embodiment 3

[0030] The extractant is TBP and sulfonamide compound N-methyl-N-(2-pyridine) ethyl isopropyl sulfonamide, its structural formula is as follows:

[0031]

[0032] Add 1 volume of salt lake brine shown in Table 1 into a separatory funnel, add a certain amount of FeCl 3 (FeCl 3 Li in brine + The molar ratio is 1:1.3) as a co-extraction agent, shake to dissolve it. Add 2 volumes of organic phase (compared to O / A=2) with N-methyl-N-(2-pyridine)ethylisopropylsulfonamide, TBP and sulfonated kerosene in a volume ratio of 1:3: 6. After shaking for 10 minutes, rest and stratify. Determination of Li in the equilibrium aqueous phase + , Calculate the extraction rate of lithium to be 81.17%. After washing, stripping, evaporation, decolorization, cooling, crystallization and drying, the Na in the product is measured + 、K + , Mg 2+ , Ca 2+ , SO 4 2- , B 2 o3 The percentage contents are 0.0026%, 0.0007%, 0.0014%, 0.0005%, 0.0010%, 0.024%, respectively.

technical field

[0001] The invention relates to a method for extracting lithium salt from brine of a high-magnesium-lithium ratio salt lake by using a solvent extraction method. Background technique

[0002] my country is a country with a large amount of lithium resources, and its proven reserves of lithium resources rank second in the world, second only to Bolivia. The salt lake lithium resources in the Qaidam Basin in Qinghai are very rich, ranking first in the country. The main feature of the lithium-rich salt lake in Qinghai is the high content of associated magnesium, and the magnesium / lithium ratio in the brine is as high as 40-1200. Because the chemical properties of magnesium and lithium are very similar, it is very difficult to separate and extract lithium, which has long restricted the development of lithium extraction industry in Qinghai brine.

[0003] Solvent extraction is a lithium extraction technology that has been studied more in China. It has the advantag...

Examples

Embodiment 1

[0019] The extractant is TBP and sulfonamide compound N,N-bis-(2-ethylhexyl)ethylsulfonamide, whose structural formula is as follows:

[0020]

[0021] The synthesis method of the above-mentioned N,N-bis-(2-ethylhexyl)ethylsulfonamide: add 0.3mol of N,N-bis-(2-ethylhexyl)amine into a 1000ml three-necked flask, add 0.33mol of Ethylsulfonyl chloride, 200ml dichloromethane, stir to cool down to -5°C~0°C, add dropwise 0.3mol ethylsulfonyl chloride / 150ml methylene chloride solution, keep the system temperature below 5°C during the dropwise addition, and complete the dropwise addition , react at 0°C for 2h, add 220ml of water, extract and keep the organic phase. The organic phase was washed with alkali and acid respectively, dried with anhydrous sodium sulfate, and spin-dried to obtain the target product.

[0022] Add 1 volume of salt lake brine shown in Table 1 into a separatory funnel, add a certain amount of FeCl 3 (FeCl 3 Li in brine + The molar ratio is 1:1) as a co-extr...

Embodiment 2

[0026] The extractant is TBP and sulfonamide compound N-methyl-N-phenylethyl ethyl sulfonamide, and its structural formula is as follows:

[0027]

[0028] Add 1 volume of salt lake brine shown in Table 1 into a separatory funnel, add a certain amount of FeCl 3 (FeCl 3 Li in brine + The molar ratio is 1:1.5) as a co-extraction agent, shake to dissolve it. Add 5 volumes of the organic phase (compared to O / A=5), wherein the volume ratio of N-methyl-N-phenylethylethylsulfonamide, TBP and 200# solvent naphtha is 4:3:3, shake for 10 After 10 minutes rest layered. Determination of Li in the equilibrium aqueous phase + , Calculate the extraction rate of lithium to be 90.96%. After washing, stripping, evaporation, decolorization, cooling, crystallization and drying, the Na in the product is measured + 、K + , Mg 2+ , Ca 2+ , SO 4 2- , B 2 o 3 The percentage contents are 0.0030%, 0.0008%, 0.0016%, 0.0005%, 0.0012%, 0.028%, respectively.

Embodiment 3

[0030] The extractant is TBP and sulfonamide compound N-methyl-N-(2-pyridine) ethyl isopropyl sulfonamide, its structural formula is as follows:

[0031]

[0032] Add 1 volume of salt lake brine shown in Table 1 into a separatory funnel, add a certain amount of FeCl 3 (FeCl 3 Li in brine + The molar ratio is 1:1.3) as a co-extraction agent, shake to dissolve it. Add 2 volumes of organic phase (compared to O / A=2) with N-methyl-N-(2-pyridine)ethylisopropylsulfonamide, TBP and sulfonated kerosene in a volume ratio of 1:3: 6. After shaking for 10 minutes, rest and stratify. Determination of Li in the equilibrium aqueous phase + , Calculate the extraction rate of lithium to be 81.17%. After washing, stripping, evaporation, decolorization, cooling, crystallization and drying, the Na in the product is measured + 、K + , Mg 2+ , Ca 2+ , SO 4 2- , B 2 o3 The percentage contents are 0.0026%, 0.0007%, 0.0014%, 0.0005%, 0.0010%, 0.024%, respectively.

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