A high-efficiency coupled method for separating magnesium and lithium in salt lake brine

By combining primary selective electrodialysis, secondary selective electrodialysis, and dual-alkali-chamber bipolar membrane selective electrodialysis with an ammonia stripping step, the cumbersome steps and environmental pollution problems of magnesium-lithium separation in salt lake brine have been solved, achieving efficient and continuous magnesium-lithium separation and the preparation of high-purity lithium hydroxide.

CN116835612BActive Publication Date: 2026-05-29INTELLIGENT MFG INST OF HFUT
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
INTELLIGENT MFG INST OF HFUT
Filing Date
2023-07-21
Publication Date
2026-05-29

AI Technical Summary

Technical Problem

Existing methods for extracting lithium from salt lake brine suffer from problems such as cumbersome procedures, poor economic efficiency, and environmental pollution, making it difficult to achieve efficient and continuous magnesium-lithium separation and purity control.

Method used

A coupled method of primary selective electrodialysis, secondary selective electrodialysis, and dual-alkali-chamber bipolar membrane selective electrodialysis, combined with an ammonia stripping step, was adopted to achieve multi-stage separation of magnesium and lithium through optimization of electrodialysis device and membrane stack configuration, ultimately yielding a high-purity lithium hydroxide solution.

Benefits of technology

This method achieves efficient separation of magnesium and lithium in salt lake brine, significantly reducing the magnesium-to-lithium mass ratio. The process is simple, easy to operate, and can be run continuously. It also reduces the generation of magnesium hydroxide precipitate and membrane fouling, resulting in significant economic benefits.

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Abstract

The application discloses a coupling method for efficiently separating magnesium and lithium in salt lake brine, which comprises the following steps: sequentially processing the salt lake brine through a first selective electrodialysis device, a second selective electrodialysis device and a double-alkali-chamber bipolar membrane selective electrodialysis device, and then feeding the obtained lithium hydroxide and ammonia mixed solution into an ammonia evaporation device to remove ammonia, so as to finally obtain a lithium hydroxide solution. The coupling method provided by the application realizes four-stage separation of the salt lake brine (one-stage magnesium / lithium separation by the first selective electrodialysis device, one-stage magnesium / lithium separation by the second selective electrodialysis device, and two-stage magnesium / lithium separation by the double-alkali-chamber bipolar membrane selective electrodialysis device), so that the magnesium / lithium separation effect is good, the mass ratio of magnesium to lithium in the salt lake brine is greatly reduced, and a lithium hydroxide solution with high purity is obtained.
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