BINDER SURFACE SEGREGATION DURING SPRAY-DRYING OF CERAMIC SLURRY

Spray-dried granules were observed by a laser microscopy with the imme rsion liquid technique. The binder distribution in the granules was an alyzed from light intensity profiles of the images. The results showed that a surface layer with a large amount of the binder is formed in t he spray-dried granule, and the segregation is influenced by initial b inder concentration and size of atomized droplet. A computer simulatio n for soluble binder segregation during spray drying was conducted by considering simultaneously the solvent evaporation, the relative migra tion between the liquid and the particles, the diffusion, and drying s hrinkage. The simulation coincides with the experimental results. To m ake uniform granules, reducing the amount of binder, liquid content, s ize of atomized droplet, and drying rate is favorable.