Method for extracting lithium from strong-acidic electrolyte solution system

Abstract

The invention provides a method for extracting lithium from a strong-acidic electrolyte solution system. The method comprises the following steps: (1) preparing an organic phase, wherein the organic phase contains an extracting agent and a diluting agent, the extracting agent is tributyl phosphate (TBP), the diluting agent is dichloromethane (DCM), and the volume ratio of TBP to DCM is (1-8) to 1;(2) preparing a water phase, wherein the water phase is an LiCl-AlCl3-CaCl2-H2O system, the concentration of LiCl is controlled at 50ppm-500ppm, and the molar ratio of Li to Al to Ca is 1 to (20-60)to (5-20); (3) adding HCl into the water phase so as to regulate the acidity to 1M-5M; (4) continuing to add a co-extracting agent FeCl3.6H2O into the water phase, and controlling the molar ratio of iron to lithium at (1-6) to 1; and (5) mixing the organic phase obtained in the step (1) with the water phase obtained in the step (4) in a volume ratio of (0.5-5) to 1, stirring at the room temperature for 3-20 minutes, and standing for separation. By utilizing the method provided by the invention, the once extraction rate of lithium reaches over 60%, the problem that the lithium is difficult to extract under a strong acidic condition is solved, and the method is good in selectivity, simple in operation, easy for two-phase separation and low in cost and can be used for extracting lithium froma coal ash acid leaching solution.

Description

technical field [0001] The invention relates to the extraction of alkali metals, in particular to an extraction system which can be used for separating lithium in fly ash acid leaching solution, and specifically belongs to a method for extracting lithium in a strong acid electrolyte solution system. Background technique [0002] Lithium plays an increasing role in many technologies such as rechargeable batteries, thermonuclear fusion, medicine, grease, dyes, adhesives and electrode welding, making the demand for lithium increase year by year. Lithium resources exist in two forms of minerals and dissolved salts. However, mineral resources are limited, and people pay more attention to the utilization of liquid lithium resources. Fly ash contains a relatively high content of lithium (about 250-1400μg / g), reaching industrial grade. The high-value utilization of fly ash can be achieved by synergistically extracting lithium on the basis of extracting aluminum and silicon from fly...

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Problems solved by technology

Patent CN104404268A invented a new type of co-extraction system and co-extraction method for extracting lithium from brine with high magnesium-lithium ratio. The invention consists of a composite extraction agent composed of imidazole ionic liquid with strong hydrophobicity and TBP, and hexafluorophosphate, etc. Co-extraction agent, the extraction rate of lithium is as high as 96.49%, which overcomes the environmental pollution problem caused by the volatilization of a large amount of organic solvents in the prior art

[0004] The above reports are mainly aimed at extracting lithium from salt lake brine, and its extraction system is suitable for neutral or generally acidic systems (pH=1-7), and the extraction of lithium in systems with stronger acidity has not been reported yet.

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