Process for extracting lithium in salt lake brine through phosphate ion liquid to produce lithium carbonate

Abstract

The invention provides a process for extracting lithium in salt lake brine to produce lithium carbonate. An extraction system comprises an extraction agent, a co-extraction agent and a diluent, wherein the extraction agent is phosphate ionic liquid containing lithium extraction functional groups, and sodium carbonate is added into solution subjected to extraction and oil removal for primary magnesium removal, after filtering, sodium hydroxide is added into the filtrate for secondary deep magnesium removal, the filtrate is concentrated, sodium carbonate is added for lithium precipitation, filtering is carried out to obtain a filter cake, washing with hot water is carried out, then drying is carried out, and the lithium carbonate is obtained. According to the extraction system, the saturation capacity of the extraction agent is increased by 1 time compared with that of an existing extraction agent and reaches 4 g / L, dilute hydrochloric acid can be used for back extraction, an organic phase is only washed with pure water so that the extraction agent can be regenerated, the process route is simplified, and the production cost is greatly reduced; and according to the process, a soap chemical sequence and an iron removal process are eliminated, so that industrial large-scale production is better facilitated.

Description

technical field

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

[0002] As a new strategic energy source, lithium is mainly used in fields such as batteries, nuclear power generation, aerospace, and medicine. Lithium resources exist in the form of solid ore and salt lake brine. my country's salt lake lithium resources are rich, especially in the Qaidam Basin in Qinghai, with reserves of 24.47 million tons (LiCl). Due to the high content of associated magnesium, magnesium in brine The / lithium ratio (mass ratio) is as high as 40-1200, which makes it very difficult to separate and extract lithium. Extraction method is one of the most promising methods for extracting lithium from brine. The system with better effect is tributyl phosphate-ferric chloride-kerosene system. In 1979, Qinghai Salt Lake Research Institute of Chinese A...

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