Granulation in spouted — attrition and other mechanisms

Abstract Experimental measurements of overhead fines from a 150 mm diameter spouted bed granulator are described. When granulating sodium chloride, the main source of overhead fines is attrition rather than spray drying of the overhead spray droplets. Attrition increases with increasing evaporation rate and for a given evaporation rate, pure water feed causes more attrition than does salt solution feed. The existence of an optimum feed rate for minimum fractional loss of solute feed by attrition is demonstrated. Related experiments in a dry spouted bed polydisperse granules show that attrition is size dependent, being lowest for intermediate granule sizes.