The application provides a method for preparing
lithium manganese iron phosphate from iron hydroxyphosphate, wherein
ferrous sulfate is purified to form a
ferrous sulfate solution,
hydrogen peroxide,
phosphoric acid,
ammonium dihydrogen
phosphate solution,
titanium sulfate and
ammonia are sequentially added into the solution to form a mixed
slurry after reaction, the mixed
slurry is heated to a certain temperature and kept for a certain time, and then
water washing and pressure
filtration are performed to form iron hydroxyphosphate precursors with different iron-
phosphorus ratios; the iron hydroxyphosphate precursors are subjected to flash
drying and high-temperature
sintering and crushing to obtain iron hydroxyphosphate precursors with different iron-
phosphorus ratios and different specific surface areas; the iron hydroxyphosphate precursors are crushed and mixed to obtain iron hydroxyphosphate finished products; high-iron-
phosphorus-ratio iron hydroxyphosphate and low-iron-phosphorus-ratio iron hydroxyphosphate are mixed according to a certain proportion, and
lithium source,
manganese source and phosphorus source are proportioned according to a certain proportion, and
carbon source and additives are added to form a mixture; and after processes such as ball milling, sand milling,
spray drying,
sintering, crushing, screening, batching and packaging are performed on the mixture,
lithium manganese iron phosphate finished products are obtained.