Study on Small Grinding Media for Sub Micron Particle Production in Stirred Media Mills

Fundamental theoretical and experimental works about grinding and crack formation in solids has been done by Schönert [1]. Based on this work he estimates the possible minimum particle size for grinding purposes to be in a range of 10 to 100 nm depending on the physical properties of the material. Investigations of the comminution of fused corundum (Al2O3) should answer the question whether and in which particle size range a lower limit of the grindability exists. During the investigations the increasing particle- particle-interactions with increasing fineness are an essential problem. Due to this interactions the viscosity of the product suspension increases and often spontaneous agglomeration of product particles occurs.

This report shows the experimental setup which allows the measurement of the most important electrochemical properties and the analysis of the particle size distribution of the product suspension as well as an adjustment of the pH-value for stabilization during the comminution process.

First results for comminution of fused corundum with different grinding media materials and grinding media sizes are shown. In addition, the influence of the electrostatic stabilization on the grinding progress is discussed.