Granulation of an insoluble powder in a spouted bed

Abstract Granulation of a finely ground phosphatic rock in a spouted bed has been carried out. Granule size distribution, sphericity and crushing strength have been measured against granulation time, for temperatures between 80 and 140°C and concentrations of corn starch (retention-aid agent) between 0 and 1.8 wt.%. The granule growth rate increased with increasing starch content and was not sensitive to temperature. Particle crushing strength increased with granulation time and starch content. The sphericity of the granules increased with granulation time. The elutriation rate decreased with starch content, but was high in all tests. Particle break-up, and hence generation of new seeds, was negligible in the process. Granule size increased exponentially with granulation time.