Comparative study of the grinding aid effects for dry fine grinding of different materials

Abstract

The production of fine particles within the lower micron range by dry grinding processes is an industrially widely used but energy intensive unit operation. Thereby, the grinding efficiency is often enhanced by applying so-called grinding aids. Even though this class of additives is established in various industrial processes, the impacts of these chemicals on the properties of the product powder as well as on the grinding process are still not understood sufficiently. Especially product-specific grinding aid effects are described very rarely within the literature. For this reason, this study presents a systematic grinding aid investigation with a special regard to different ground materials. It was shown how additives from different substance classes influence the surface energies of different particulate products, and thus, their particle and powder properties. As a result, most of the investigated grinding aids indeed act highly solid-specific. It is further discussed how additive-induced changes of the powder behavior affect the stressing conditions inside the mill as well as the grinding result. While flowability-assisting additives mostly enhance the grinding efficiency within the used lab-scale vibration mill, rather low flowabilities may be beneficial for other mill types and combinations of process parameters. This study will therefore help to understand how to optimize grinding aid applications in terms of powder properties and grinding conditions.