CRYSTALLIZATION AND AGGLOMERATION KINETICS DURING THE BATCH DROWNING-OUT PRECIPITATION OF POTASH ALUM WITH AQUEOUS ACETONE

Kinetic processes occurring during the batch drowning-out precipitation of potash alum with aqueous acetone achieved by mixing aqueous saturated potash alum solutions with aqueous acetone at 25-degrees-C over a range of supersaturation levels and under different stirring modes are reported. The induction period decreases significantly both with initial supersaturation and stirrer speed. Primary heterogeneous nucleation is predominant, with homogeneous nucleation becoming significant at S > 4.50. Weak secondary nucleation is also detected under the conditions studied. The degree of agglomeration has been assessed and found to be dependent on initial supersaturation.