Preparation method and application of iron phosphate

A preparation method of iron phosphate, wherein the preparation method comprises steps of:

• step (1):
• subjecting iron phosphate waste to calcination to obtain calcinated waste, dissolving the calcinated waste in an acid solution, and filtering a resulting solution to obtain filtrate, the filtrate being a solution A containing iron and phosphorus elements;
• step (2):
• stirring a mixed solution of the solution A obtained in step (1) and a first alkali solution, adjusting pH of the mixed solution to acidity for reaction, and after washing and filtering to obtain second filter residue, the second filter residue being an amorphous yellow iron phosphate filter cake;
• step (3):
• subjecting the yellow iron phosphate filter cake to aging, slurrying and heating, adding orthophosphoric acid and a second alkali solution thereto for reaction, followed by washing and filtering to obtain third filter residue, the third filter residue being a basic ammonium iron phosphate filter cake, then drying the basic ammonium iron phosphate filter cake to obtain basic ammonium iron phosphate crystal powder;
• and
• step (4):
• subjecting the basic ammonium iron phosphate crystal powder to calcination for dehydration and cooling to obtain the iron phosphate;
• wherein
• in step (3), the orthophosphoric acid has a mass concentration of 80% to 90%, and after the orthophosphoric acid is added, a molar ratio of total iron to total phosphorus in a system is 1:(1.1-1.4);
• a formula of the basic ammonium iron phosphate is NH4Fe2(OH)(PO4)2·2H2O, and the basic ammonium iron phosphate has D50 of 1.5 μm-10 μm, tap density of 0.70 g/cm3-1.30 g/cm3, and specific surface area of 40 m2/g-60 m2/g;
• and
• the iron phosphate has D50 of 1 μm-10 μm, tap density of 0.80 g/cm3-1.30 g/cm3, and specific surface area of 5 m2/g-10 m2/g.