Battery-grade lithium carbonate preparation method based on phase transformation

The invention relates to a battery-grade lithium carbonate preparation method based on phase transformation, belonging to the technical field of the preparation of inorganic chemical materials. The preparation method comprises the following steps: by taking lithium concentrate as a raw material, first mixing the lithium concentrate and water to prepare 10 to 50% serous fluid, then adding a phase transformation agent, and reacting for 0.5 to 5 hours at 10 to 100 DEG C to obtain a high-concentration lithium salt solution; then mixing the lithium salt solution and inorganic alkali, and reacting to obtain a high-concentration causticization solution; introducing the causticization solution into a cation exchange column to obtain a refined causticization solution, and then introducing carbon dioxide into the refined causticization solution to obtain crude lithium carbonate; and finally mixing the crude lithium carbonate and an appropriate amount of composite refined impurity removal agent in water, and reacting to obtain a battery-grade lithium carbonate product with a main content more than or equal to 99.5 percent by weight. By adopting the phase transformation method, the concentration of the lithium salt solution is remarkably increased, the high-concentration causticization and carbonization can be realized, the preparation efficiency of the battery-grade lithium carbonate is increased, and a novel way is provided for the industrialized preparation of the battery-grade lithium carbonate.