AGGLOMERATION DURING PRECIPITATION .1. TRACER CRYSTALS FOR AL(OH)(3) PRECIPITATION

Tracer crystals are developed to study the agglomeration, growth and r esidence time behavior of gibbsite crystals, an industrially important polymorph of Al(OH)(3), in continuous and batch precipitation. Satisf actory tracer crystals contain detectable amounts of Zn and have the c rystal structure of gibbsite. The tracer crystals behave in the same m anner during precipitation as the nontracer Al(OH)(3) crystals. The ap plication of the tracer crystals for investigating, both batch and con tinuous, seeded Al(OH)(3) precipitation is demonstrated. The tracer ex periments provide information on the growth and agglomeration kinetics of different size fractions. The tracers are a useful tool for the qu antitative investigation of solid-phase residence time distributions w ithin a crystallizer.