Nano-filtration method for separating magnesium and enriching lithium from salt lake brine

Abstract

The nanofiltration process is suitable for Mg-Li separation and Li enriching of Li containing bittern or Li containing solution from salt lake to prepare lithium carbonate or lithium chloride with the Li enriching bittern. Nanofiltration membrane is used in separating and enriching lithium from lithium containing bittern, which contains Mg, Ca and other cations and sulfate radical and other anions and has Li ion concentration of 0.1-11.5 g / L and Mg / Li ion weight ratio 1-200, to obtain lithium enriched bittern suitable for preparing lithium carbonate or lithium chloride. The said process is effective, and can obtain lithium enriched bittern with Mg / Li ion weight ratio 0.6-5 and Li ion content of 0.6-20 g / L.

Description

technical field [0001] The invention relates to a method for separating magnesium and enriching lithium from salt lake brine by nanofiltration, in particular to a method for separating magnesium and enriching lithium from lithium-containing brine or lithium-containing solution obtained from salt lake. Background of the invention [0002] In the traditional process of extracting lithium from ores, sulfuric acid and spodumene are first roasted together, and then the roasted product is soaked with water, and the obtained lithium sulfate solution is treated with lime and soda ash to remove magnesium and calcium, and then Lithium carbonate precipitated out. Other treatment methods include the so-called alkali method and ion exchange method. The lithium solution obtained by these methods is lithium hydroxide, lithium chloride or lithium sulfate. These methods also include the steps of removing magnesium and calcium from the solution with lime and soda ash. [0003] However, the e...

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Problems solved by technology

Among them, electrolysis and membrane electrolysis are aimed at producing lithium salt compounds, but magnesium and calcium still need to be removed in advance, and a large amount of hydrogen and chlorine will be generated, which is seriously unfavorable to production

The tributyl phosphate extraction method uses concentrated lithium-rich and high-magnesium brine as the production raw material, and the yield is relatively high, but the process is long, the equipment is severely corroded, and the production cost is high, so it is difficult to realize industrialization

The adsorption method uses resin to selectively adsorb lithium ions, but the resin is expensive, has low adsorption capacity, is easily polluted by brine and is difficult to regenerate, and its industrialization is limited by both scale and cost.

The precipitation method is feasible, but the process is long, the yield is low, the turnover of materials is large, the operation is complicated for multiple calcination and filtration, the concentration of lithium in the hydrothermal decomposition or roasting leaching solution is low, and a large amount of water needs to be evaporated when concentrating