Bipolar membrane-assisted ion rectification method for preparing battery-grade lithium product from salt lake brine in one step

Abstract

The invention discloses a bipolar membrane-assisted ion rectification method for preparing a battery-grade lithium product from salt lake brine in one step. Firstly, an ion rectification system is arranged, which consists of a plurality of monovalent and multivalent cation selective membranes and a plurality of monovalent and multivalent anion selective membranes according to the principle of 'same type at the same side'. Chloride ions and lithium ions are selectively screened by a plurality of monovalent and multivalent cation and anion selective membranes,impurity ions are selectively blocked, after n-stage separation, the selectivity coefficient among the chloride ions, the lithium ions and the impurity ions is amplified in stage number, and the chloride ions, the lithium ions and the impurity ions are combined with hydroxyl and hydrogen ions generated by hydrolysis of a bipolar membrane in a rectification chamber of the nth stage, and therefore, a battery-grade lithium hydroxide product and a hydrochloric acid product are obtained. According to the invention, the selectivity coefficient of lithium ions and chloride ions is determined by the plurality of monovalent and multivalent anion and cation selective membranes which are used in an overlapped manner, so that the requirement on the characteristics of a special diaphragm is greatly reduced, and the purity and the quality of a salt lake lithium extraction product are greatly improved.

Description

technical field [0001] The invention belongs to the field of electric-driven membrane separation, in particular to a bipolar membrane-assisted ion rectification method for one-step production of battery-grade lithium products from salt lake brine. Background technique [0002] Special ion separation is an important chemical separation technology, which occupies an important position in the field of lithium extraction from salt lakes. Lithium is the lightest metal with extremely strong electrochemical activity. Its metals and compounds have been rapidly developed in the fields of high-energy lithium batteries, nuclear fusion power generation, aerospace, ceramics, lasers, and medicine. Especially with the continuous development of China's industry, lithium batteries for storing electric energy are developing rapidly, and the demand for high-purity lithium hydroxide necessary for lithium batteries is also increasing. Many countries have considered it as a strategic material re...

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Problems solved by technology

Therefore, in the selective electrodialysis process, the separation performance of special ions still depends on the screening characteristics of the functional membrane itself, and the unsatisfactory screening performance of the functional membrane also limits the separation efficiency of target ions.

[0006] Similar to the traditional special ion separation process, such as ion exchange, solvent extraction, ion sieve adsorption, etc., the industry needs to achieve the target screening of lithium ions through the coupling and integration of multiple selective electrodialysis units. At this time, selective electrodialysis itself The characteristics of continuous operation cannot be effectively reflected

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