The purpose of this study was to investigate the effects of different initial volume fill ratios of the granulator on granular agglomeration in a high-shear mixer. Calcium carbonate powders, with mean granule sizes of 75-150 mu m were used as the raw material. Polyethylene glycol 6000 (PEG 6000) was used as the melting binder. The initial liquid to solid weight ratio was fixed at 0.15. Four different initial granulator fill ratios were used 11%, 14.7%, 18.4% and 22%. The results showed that the granules that formed during the nucleation stage were a little larger when the initial fill ratio was lower than higher. In the rapid-growth stage, the agglomeration growth rate increased as the initial fill ratio increased. The range in granule size at the end of agglomeration also increased as initial fill ratio increased. SEM images of the surface structure of the granules during the nucleation and final stages are shown. (C) 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.