The invention belongs to the technical field of inorganic material preparation, and particularly relates to a method for preparing battery-grade
lithium dihydrogen
phosphate by using a waste
lithium molecular sieve, which comprises the following steps:
grinding the waste
lithium molecular sieve, sieving with a 100-mesh
sieve, mixing with a diammonium
hydrogen phosphate solution, adding
oxalic acid solid, adjusting the pH value of
slurry to 5-6, stirring, and filtering to obtain filter residue and filtrate; performing the operations on the filter residue, filtering, and mixing with the first filtrate to obtain a solution 1; adding EDTA (
Ethylene Diamine Tetraacetic Acid) into the solution 1, stirring, adding
lithium hydroxide monohydrate, adjusting the pH value to 12.5-13, heating until boiling, and filtering while hot to obtain a
lithium phosphate wet material; then adding pure water to obtain
slurry, adding the
slurry into
phosphoric acid and
hydrogen peroxide, and dissolving and clarifying to obtain a lithium dihydrogen
phosphate clean solution; and then evaporating, stopping heating when the temperature of the solution reaches 125-130 DEG C, cooling, and then centrifuging and
drying to obtain the battery-grade lithium dihydrogen phosphate. According to the invention, zero
discharge of waste liquid is realized, and the lithium yield is high.