Method for preparing battery-grade lithium carbonate

Abstract

The invention provides a method for preparing battery-grade lithium carbonate based on salt lake old halogen, which comprises the following steps: S1, preliminary magnesium lithium separation of saltlake old brine; S2, reverse osmosis first stage concentration; S3, electrodialysis second stage concentration; S4, deep magnesium removal; and S5, preparation of battery-grade lithium carbonate. Withthe method for preparing battery-grade lithium carbonate with a high magnesium-lithium ratio by magnesium lithium separation, lithium enrichment and deep magnesium removal provided by the invention, the technical problems that conventional methods are complicated, high in cost and unsatisfactory in separation effect of magnesium and lithium can be effectively solved, in the preparation process oflithium carbonate, the process flow is greatly shortened, a plurality of processes such as forced evaporation, adjustment of pH, purification of lithium carbonate and conversion from two-step magnesium removal into one step of magnesium removal are reduced, the cost of preparing battery-grade lithium carbonate is also greatly reduced, and better industrialization prospects are achieved.

Description

technical field [0001] The invention belongs to the technical field of inorganic salt preparation, and in particular relates to a method for preparing battery-grade lithium carbonate. Background technique [0002] Lithium is the lightest metal element in nature, silver-white, with unique physical and chemical properties such as high specific heat, high electrical conductivity and strong chemical activity, and has a wide range of uses. At present, metallic lithium and its compounds are used in glass ceramics, electrolytic aluminum, Applications in traditional industrial fields such as grease, air-conditioning and refrigeration, organic synthesis, metallurgy, chemical industry, medicine, and reagents continue to grow, and applications in energy, military, aerospace, and nuclear industries such as aluminum-lithium alloys, lithium batteries, and nuclear fusion are also increasing. It is rapidly expanding, so it is known as "industrial monosodium glutamate" and is also regarded a...

AI Technical Summary

Problems solved by technology

This patent application enriches the concentration of lithium ions to 16,000ppm through the method of multi-stage reverse osmosis, and the salt content in the enriched solution will reach about 10%. However, under high concentration conditions, using reverse osmosis process for enrichment and concentration will increase investment Cost and equipment energy consumption

[0006] In summary, in the prior art, for the salt lake brine treatment method with high magnesium-lithium ratio, there are generally problems in the following aspects: (1) the existing nanofiltration for magnesium-lithium separation, reverse osmosis and electrodialysis for lithium concentration after lithium concentration The concentration is low, and the conversion and precipitation of lithium cannot be directly prepared to prepare lithium carbonate; (2) after the separation of magnesium and lithium, the deep magnesium removal needs to be carried out in two steps, first adding soda ash, then adding caustic soda, the process is complicated and the cost is high; (3) magnesium removal Finally, the solution needs to be added with hydrochloric acid to adjust the pH, so that the solution is neutral to be evaporated and concentrated, which increases the cost; (4) the obtained magnesium-containing lithium-containing solution needs to be further enriched and concentrated before it can be converted and prepared lithium carbonate. Forced evaporation means, large investment, high energy consumption, and high cost; (5) Lithium carbonate prepared from salt lake brine is mostly industrial grade, in which impurity ions such as chloride ions, sodium ions, and magnesium ions are relatively high, and cannot reach battery-grade lithium carbonate requirements