Estimation of product relating energy of wet operated stirred media mills in terms of process transfer to other mill geometries and sizes

Abstract

Wet grinding with stirred media mills is a wide distributed unit operation which occurs in many different industrial areas from milliliter to cubic meter scale. For different applications diverse rotor, stator and grinding media separation systems were developed. The transfer from one scale or mill type to another is a challenge in the process development. Scale-up rules for geometrically similar mills exist but reach fast their boundaries when changing the mill geometry. Besides the mill dependent values each material and particle size needs a certain breakage energy which is provided by colliding grinding media and which has to be considered for those transfer processes as well. Thus the transferred energy depends on the process parameters, the mill geometry and the formulation of the suspension including material and rheological parameters. The introduced energy is reduced to a product relating amount. This product relating energy can be optimized following the stress model, thus an estimation of optimum process parameters for different geometries and materials is possible which offers the chance to transfer processes in an energetically efficient way with a low experimental effort.