Preparation method of battery-grade lithium carbonate

Abstract

The invention discloses a preparation method of battery-grade lithium carbonate. The preparation method comprises the following steps: taking a lithium adsorption and desorption eluent as a raw material, performing primary and secondary monovalent ion selective electrodialysis treatment, concentrating and enriching a lithium ion by utilizing the monovalent ion selectivity of a monovalent ion selective cation membrane and a monovalent ion selective anion membrane, and intercepting magnesium ions, sulfate ions and borate ions, thereby realizing efficient separation of lithium and magnesium as well as sulfate and borate ions and other impurity ions and lithium concentration and obtaining a lithium-rich concentrated solution with a lithium content of 10-20 g / L and a ratio of magnesium to lithium of 0.1-1; obtaining the battery-grade lithium carbonate through the steps of deep calcium and magnesium removal, heavy lithium conversion, filtering and washing, drying, cooling and the like. According to the preparation method disclosed by the invention, the preparation process of the battery-grade lithium carbonate is greatly shortened, the process continuity is obviously improved, the cost is reduced, and the bottleneck problem of magnesium removal and concentration by using the salt lake lithium adsorption and desorption eluent with high magnesium-lithium ratio is solved.

Description

technical field [0001] The invention belongs to the technical field of material preparation, and in particular relates to a method for preparing battery-grade lithium carbonate. Background technique [0002] Using salt lake, geothermal, oilfield water, seawater and other high-magnesium-lithium ratio and low-grade liquid lithium ores as raw materials, lithium is extracted by adsorption method, and the concentration of lithium chloride in the obtained lithium-rich eluent is generally lower than 1000mg / L, and entrained There are more magnesium salts and a small amount of impurities such as sulfate and borate, and the ratio of magnesium to lithium is higher than 1, even reaching more than 10. It must be further removed from magnesium and enriched before it can be used for lithium carbonate, lithium chloride, etc. Preparation of basic lithium salts. The existing treatment technology generally adopts precipitation method, cation exchange method or nanofiltration method to remove ...

AI Technical Summary

Problems solved by technology

The repeated use of the eluent is complicated, resulting in long adsorption-regeneration time, low efficiency, and large consumption of adsorbent; the load of cation exchange to remove calcium and magnesium is also high, and the cost of resin regeneration is high; electrodialysis only affects the eluent The lithium in the

The joint application of the three steps has a long process, low overall efficiency and high cost

However, the average concentration of lithium in the enrichment solution obtained by this method is lower than 4g / L, and the resin adsorption and regeneration load is large, and the loss of lithium is relatively large.

[0007] U.S. Patent 6764584 discloses a method for obtaining concentrated lithium solution from seawater or brine. Lithium manganate adsorbent will be used to absorb and extract lithium, and the obtained eluate will be concentrated by two-stage conventional electrodialysis to obtain lithium containing 1.5%. Concentrate of about 1000000000000000000000000000000000000000000000000000000000000000000000s of solution, but the electrodialysis that this method uses is conventional electrodialysis, the magnesium in the eluent that ratio of magnesium lithium is taller does not have separation action to the magnesium

[0008] None of the methods disclosed above achieves the separation of magnesium and lithium and the concentration of lithium by one method. While removing a large amount of magnesium, the lithium is concentrated to more than 10g / L or higher, and at the same time significantly reduces the concentration of lithium in the eluent for adsorption and extraction of lithium. The content of impurities such as sulfate and borate, so as to obtain a lithium-rich concentrated solution that can be directly used to prepare lithium carbonate or lithium chloride with high purity

In actual application, the overall efficiency is low, the continuous production stability is poor, and the purity of lithium carbonate products is difficult to reach more than 99%.

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