A METHOD OF CRYSTALLISING ALUMINIUM SULPHATE SOLUTION TO DUST-FREE GRANULES

摘要

A method of crystallizing a solution of aluminium sulphate to form crystal agglomerates having an essentially uniform grain size and being in the form of granules having a characteristic appearance and good storage properties. A solution having a temperature of 105 DEG -115 DEG C. and a concentration of 14.5-16.8% by weight of Al2O3 is brought to crystallize onto a bed of crystalline aluminium sulphate in a drum, the length of which is considerably larger than the diameter, a temperature of 70 DEG -95 DEG C. being maintained in the bed. Part of the crystalline product discharged from the drum is ground and recycled to the drum in an amount of 40-200 percent by weight of added solution and air is passed through the drum to remove moisture evolved by the crystallization so as to form a final product with more than 75% by weight present in the crystalline state and containing 15.0-18.0% by weight of Al2O3.