Method for preparing lithium phosphate and co-producing basic magnesium carbonate from lithium precipitation mother liquor

A method for preparing lithium phosphate and co-producing basic magnesium carbonate from lithium precipitation mother liquor relates to the technical field of extraction of lithium from brine, and comprises the following steps: heating the lithium precipitation mother liquor: reacting the lithium precipitation mother liquor and a phosphate solution in a ratio of 0.98:1 at 80-85 DEG C for 1.5-2 hours to obtain slurry containing solid lithium phosphate; separating the slurry to obtain a crude lithium phosphate product, wherein the tail liquid is used as a raw material for producing basic magnesium carbonate; carrying out preliminary acid adjustment on the tail liquid through hydrochloric acid; adjusting the pH of the tail liquid, and mixing the tail liquid with nanofiltration concentrated water according to the volume ratio of 3:1 to generate basic magnesium carbonate; carrying out filter pressing dehydration and washing on the basic magnesium carbonate solution; and carrying out flash evaporation drying on the