The invention relates to the technical field of
iron phosphate production, and discloses a battery-grade
iron phosphate production method based on
raffinate acid and a preparation method of
lithium iron phosphate thereof, and the method comprises the following steps: 1) adjusting the pH value of the
raffinate acid with
ammonia water, adding a fluorination auxiliary agent, carrying out heat preservation stirring, and filtering to obtain a filtrate A; (2) taking the preheated and
impurity-removed
ferrous sulfate solution as filtrate B, adding a mixture of the filtrate A and
hydrogen peroxide into the filtrate B, regulating the pH value of the
system by using
ammonia water, preserving heat for at least 30 minutes, and filtering to obtain a primary
filter cake; 3) washing the primary
filter cake until the
conductivity of the washing water is less than 3.5 ms / cm, mixing
phosphoric acid, pure water and the
filter cake for size mixing, aging until the color of the size is changed, continuously keeping the temperature, filtering, washing the secondary filter cake until the
conductivity of the washing water is less than 2.5 ms / cm,
drying, calcining and crushing to obtain battery-grade iron
phosphate; the
raffinate acid is used for replacing monoammonium
phosphate or
diammonium phosphate, the preparation process is shortened, the production efficiency is improved, and the material meeting the requirements of battery-grade iron
phosphate can be directly prepared.