Effect of operating variables on the production of nanoparticles by stirred media milling

This paper investigates the effect of major operating variables on the production of stable nanoparticle suspensions in an attritor mill, which can serve as guidelines for the selection of major operating variables for desired comminution. Experimental work has been carried out to study the effect of major operating variables, such as slurry solid mass fraction, grinding media size, density and pin tip velocity on the milling efficiency of silica. The effect of these major operating variables on the variation of width of product size distribution was studied using response surface methodology. Size reduction was found to increase with increasing value of slurry solid mass fraction, until it reached a maximum and then decreased. The use of grinding media of smaller diameter was found to cause higher rates of size reduction and narrower particle size distribution than the use of larger grinding media. Pin tip velocity was found to be an important parameter affecting comminution results. Size reduction was found to increase on the order of increasing pin tip velocity, until it reached a maximum and then decreased. Grinding media of higher density was found to be more effective for size reduction and production of a narrower product size distribution. The results suggest that these variables affect the energy required to achieve a given product size during nanomilling. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.