Preparation method of low-cost iron phosphate

The invention discloses a preparation method of low-cost iron phosphate. The preparation method comprises the following steps: preparing vanadium chloride and ferric chloride into a solution, uniformly stirring to obtain an iron-vanadium mixed solution, uniformly stirring and mixing the iron-vanadium mixed solution and a phosphoric acid solution, then adding into a sealed reaction kettle, communicating the sealed reaction kettle with a vacuum pump, starting the vacuum pump, carrying out reduced pressure evaporation until water is completely evaporated to be dry, carrying out 2-4 stages of countercurrent spraying absorption on the condensed tail gas, discharging the tail gas meeting the standards, pouring out powder obtained after evaporation drying, putting the poured powder into a rotarykiln for calcining until the mass fraction of high-temperature moisture of the material is lower than 0.5%, then carrying out jet milling, screening and iron removal, and then carrying out vacuum packaging to obtain the batte