To provide a method for the purification or recovery of orthophosphoric acid rich streams by suspension-based melt crystallization.

The orthophosphoric acid is crystallized as the hemi-hydrate form and subsequent separation of such crystals in a wash-column produces a high purity acid/water solution that has been deleted of most of the metals and impurities other than water, thereby separating an orthophosphoric acid rich feed liquor into an ultra-pure orthophosphoric acid hemi-hydrate and a mother liquor containing almost all impurities originally present in the feed. The orthophosphoric acid rich feed liquor typically contains 15 mass% water and 1 mass% other impurities. Individual metal ion composition in the purified orthophosphoric acid product is in the range of 100-1,000 ppb of each metal ion. The metal ion composition of the resulting purified product is thus typically below the detection limit of typical analysis equipment.