Effects of cadmium on the formation of phosphogypsum during phosphoric acid production

Phosphoric acid manufacture by the wet process, which forms the basis of phosphate fertilizer manufacture, results in redistribution of cadmium in the phosphate ore between the phosphoric add and the waste calcium sulphate. We conclude that the maximum amount of cadmium in the calcium sulphate produced in the wet process by sulphuric acid with apatite phosphate is 0,62% and the cadmium amount in phosphoric acid is lower than in the corresponding solids. When the cadmium concentration contained phosphoric acid is lower, the increase of this amounts is affecting the physico-chemical properties without affecting the percent of P2O5. In high concentration of cadmium, this element can be precipitated in the form of a phase CdSO4,H2O and CdHPO4,2H(2)O.