NO133135B

1371270 Phosphate fertilizer KALI-CHEMIE AG 20 April 1972 [5 June 1971] 18439/72 Heading C1A A calcined alkali metal phosphate fertilizer is made by reacting, in a rotary kiln, a natural calcium phosphate feed with optionally extra added silica with alkali metal hydroxide, the hydroxide being introduced such that it contacts the phosphate feed when the latter has been heated to a temperature of at least 400‹ C., the rotary motion of the kiln effecting homogenization and passage of the product to the calcining zone at 900-1300‹ C., the proportion of reactants being such that 1À1 to 1À5 moles of alkali metal oxide are present per mole of P2O5 and the total amount of silica present being such that calcium orthosilicate forms by reaction of the silica with one mole of CaO from each mole of the tricalcium phosphate present and with any free lime present.