Method for extracting lithium from brine

Abstract

The invention discloses a method for extracting lithium from brine. According to the method, tributyl phosphate, an amide compound and a diluent are used as extraction agents and ferric salt as a co-extraction agent to extract the brine. The method comprises the following steps of: (1) preparing the co-extraction agent into a solution to obtain a co-extraction agent solution; carrying out mixed extraction on the co-extraction agent solution, the tributyl phosphate and the diluent, and separating to obtain a first organic phase; (2) adding the amide compound, the tributyl phosphate and the diluent into the first organic phase to obtain a second organic phase; and (3) mixing the second organic phase with the brine, extracting, and separating to obtain a lithium-containing extracting solution. According to the method for extracting the lithium from the brine, an emulsification phenomenon easily occurring during extraction of the tributyl phosphate and the amide compound can be eliminated,smooth operation of an extraction process is ensured, application limitation of an amide extraction agent is reduced, corrosion condition of extraction equipment during extraction can be reduced, andthe industrial application of the tributyl phosphate and the amide compound as the extraction agent is facilitated.

Description

technical field [0001] The invention relates to the field of chemical metallurgy, in particular to a method for extracting lithium from brine. Background technique [0002] The content of lithium in salt lake brine is relatively high, accounting for 66% of the world's lithium reserves and more than 80% of the lithium reserve base. Lithium extraction from salt lake brine has the advantages of rich resources, simple process, low cost, and strong market competitiveness, and has become the main way to develop and produce lithium salts at home and abroad. my country is rich in lithium resource reserves, ranking second in the world's currently proven lithium resource reserves, of which liquid ore lithium resources account for 79% of China's total lithium resources. Lithium-containing salt lake brines in China generally have a high magnesium-lithium ratio of 40 to 1800. How to extract lithium from salt lake brines with high magnesium-lithium ratios is a difficult problem. Domesti...

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Problems solved by technology

However, the concentration of tributyl phosphate in this system is high, which severely corrodes the extraction equipment, and tributyl phosphate degrades in acidic medium, especially its severe swelling effect on plastic materials limits its application. Adding amide compounds to butyl ester and diluent to form a composite extraction system can effectively reduce the amount of tributyl phosphate and reduce its application restrictions, but the amide compounds in the extraction system are weakly alkaline, and the ferric iron in the solution It is easy to hydrolyze ferric iron during contact and emulsify the extraction process, which seriously restricts its industrial application