GRINDING AND FLOWING INVESTIGATION ON DRY STIRRED BALL MILLING IN ORDER TO DETERMINE THE INFLUENCE OF GRINDING AIDS

摘要

Huge difficulties of the great ultra fine ground material production in dry stirred ball mill are therncohesion and agglomeration of the particles. During grinding the material stick on the grinding wallrnand the grinding media furthermore the grinds start cohere, making aggregation and agglomerationrnto appear. Due to these effects the particle size will not decrease after a certain value during grindingrnand the energy demand increases significantly. According to experience on fine grinding in ball mill,rnit is well known that these effects can be reduced with the use of grinding aids. The influence ofrngrinding aids has three different effects: due to the adsorption strength reduction (Rebinder effect) therngrinding resistance of the material decreases; the surface energy diminishes and the agglomerationrnliability decreases; and the flow properties of material improve. The aim of this study is to investigaternthe flow properties of fine grinds and the effect of grinding aids on flow properties in case of dryrnstirred ball milling. In addition, the influence of grinding aids was investigated based on the particlernsize distribution and specific surface area of grinds and the specific energy demand of grinding. Thernexaminations were carried out with three different model materials (limestone, clinker, quartz)rnusing the usually applied grinding aid. The flow properties were measured by the Jenike shear cell;rnthe particle size distribution and specific surface area were measured by laser particle size analyserrn(Fritsch Analysette 22), grinding energy demand was measured with microcomputer controlledrndigital energy meter. It can be said that under certain measuring circumstances the influence ofrngrinding aid on flow properties can be demonstrated by Jenike shear cell, so the grinding result is inrncorrelation with the flow properties of grind.