Preparation of Li2CO3 from high Mg2+/Li+ brines based on selective-electrodialysis with feed and bleed mode

Extracting lithium from brines is challenging due to the high Mg 2+ /Li + ratio and low Li + concentration. In this paper, a selective electrodialysis process (S-ED) with feed and bleed mode was developed to extract Li + continuously from brines. Take the system performance including the recovery ratio of Li + ( R Li ), leakage ratio of Mg 2+ ( L Mg ), migration rate ( M r ), specific energy consumption ( E SEC ), current efficiency ( η ) and separation coefficient of Li + and Mg 2+ ( F Li-Mg ) as evaluation parameters, the typical factors such as applied voltage, supplementary feed flow rate, and linear flow velocity were investigated. In addition, the Li + extraction parameters of different feed solution species in the S-ED process were compared under optimization operating conditions and Li 2 CO 3 was obtained from Li-rich solution by precipitation reaction. The results showed that the increase of voltage could promote R Li , but the excessive voltage caused a decrease in F Li-Mg . The increase of the linear flow velocity could increase M r but hardly affected F Li-Mg and E SEC . The increase in the supplementary feed flow increased F Li-Mg . For different feeding solutions, it was found that extracting Li + from bittern had good economic value and high purity Li 2 CO 3 was obtained after S-ED. Compared with the traditional process, the S-ED process with the “feed and bleed” mode proposed in this article has the advantages of simple operation, continuity, and environmental friendliness. It is a promising technology that can continuously enrich Li + from brines. SYNOPSIS Selective-electrodialysis(S-ED) with feed and bleed mode was proposed to prepare battery-grade lithium carbonate continuously from high Mg 2+ /Li + brines. • A selective electrodialysis process (S-ED) with feed and bleed mode was developed. • The continuous S-ED can extract Li + continuously from high Mg 2+ /Li + ratio brines. • The continuous S-ED process has better industrialization potential than batch S-ED. • Typical factors that affect the continuous S-ED process were investigated. • Extracting Li + from bittern by continuous S-ED process had good economic value.