Pulverization of rice husks and the changes of husk densities

Abstract

Well-dried rice husks were pulverized using a rotating knife cutter, and then classified using sieve separation technique. Most of the milled rice husks, which were screened by a 40-mesh sieve at the bottom of the cutter, were found to be in the range of −50/+100 mesh. Morphology of the milled rice husks drastically changed with size from a flake-like shape at +70 mesh to a dust-like shape at −325 mesh. Tap density of unmilled raw rice husks was about 0.1 while that of milled rice husks was over 0.4. True densities of milled rice husks were higher than 1.4, and increased with decreasing milled husk sizes. Compared to bulky raw rice husks, the pulverized rice husks can be handled as a powdery material for further industrial processing.