Production of fine Sr-ferrite particles in a vertical stirred grinding mill under various grinding conditions

Grinding studies using a vertical stirred mill were carried out in order to produce fine Srferrite particles. Laboratory tests were conducted in dry and wet conditions, and dry condition using methanol as a grinding aid. The operational variables in the stirred mill were the grinding ball size, the feed mass of sample, and the volume of water (wet condition). The size distribution of ground products was measured by the microscopic method, and could be expressed by a modified Gaudin-Schuhmann equation. The products were evaluated by the median particle size and the ratio of 10% and 90% cumulative weight passing sizes in the undersize distribution. The results of testing showed that the grinding ball size affected especially the fine grindability of the Sr-ferrite particles at each grinding condition. The product size of the Sr-ferrite particle in the stirred mill was finer than that in the ball mill; particles with a median particle size of 0.2-0.4μm were obtained in wet grinding.