CONTROLLED COOLING CRYSTALLIZATION OF (NH4)2SO4 IN THE TERNARY-SYSTEM (NH4)2SO4-NH4NO3-H2O

The maximum allowable undercoolings of ammonium sulfate in the ternary system ammonium sulfate-ammonium nitrate-water were measured. The nucleation parameters, which may be obtained from maximum allowable undercooling measurements, are shown to be dependent on the saturation temperature of the solution in the ternary system. These data were employed along with a supersaturation balance to calculate the optimum cooling curves in a batch cooling crystallizer. The results show that controlled cooling that takes into account the effect of the cooling rate on the maximum allowable undercooling improves the product crystal size distribution.