Novel method for preparing battery grade lithium carbonate by using tantalum niobium tailings lithium mica

The invention provides a novel method for preparing battery grade lithium carbonate by using tantalum niobium tailings lithium mica. The method is characterized by comprising the following steps of: crushing lithium mica powder until granularity is 100 to 200 meshes, adding the crushed lithium mica powder and 30 to 70 percent sulfuric acid solution in a solid and liquid mass ratio of 1:(2-8) into a reaction device, reacting at the temperature of between 60 and 200 DEG C for 3 to 10 hours to obtain the sulfuric acid solution which contains Li , and separating to remove fluorine-containing solution; performing filtering separation on the sulfuric acid solution which contains the Li , and fully washing the filter residue with water to remove the filter residue and obtain filtrate which serves as mother liquor 1; changing the temperature of the mother liquor to be between 10 and 100 DEG C with stirring, separating solids, namely rubidium, caesium and alum, performing filtering separation, washing the filter residue, and recovering the filtrate as mother liquor 2; adding calcium hydroxide into the mother liquor 2, and controlling the pH value of the solution to between 2 and 7 to obtain solid and liquid mixed solution of neutralization reaction; performing filtering separation on the solid and liquid mixed solution, washing and filtering the filter residue, and recovering the filtrate as mother liquor 3; performing evaporation concentration on the mother liquor 3, controlling the concentration of the Li in the solution to be between 40 and 65g/l, and filtering to obtain the filtrate serving as mother liquor 4; and blowing carbon dioxide into the mother liquor 4 at the temperature of between 95 and 105 DEG C under 2 atmospheres and performing lithium-sinking reaction for 40 to 100 minutes, filtering and mechanically separating to obtain lithium carbonate, washing with water, and drying to obtain the battery grade lithium carbonate product.