Abstract
Roller mills have come to be actively used for the production of fine particles. In this paper, stress conditions in a roller mill were simulated by the slow compression of powder beds between parallel platens, and compressive crushing of brittle materials in powder beds was also carried out to fundamentally study the grinding mechanism of a roller mill. The effect of the feed size on the production of fine particles was investigated when the applied load and the mass of the feed were constant. The crushing energy is defined as the energy input in a powder bed. The specific crushing energy to produce fine particles (the crushing resistance) was experimentally calculated. The samples used were limestone, quartz, and quartz glass.
The following results were obtained:
(1) When the applied load and the mass of feed were constant, the feed size with a minimum deformation of powder beds was observed.
(2) The size distribution of the crushed product changed depending on the kinds of solids, and the difference in the size distributions increased with the decrease in the feed size.
(3) The feed size with the same mass of micronized product was observed and found to have a certain range. This range was enlarged with the decrease in the size of the product.
(4) The specific crushing energy to produce fine particles changed with the kinds of solids and feed size.
(5) Then, in order to produce micronized particles for a higher energy utilization by a roller mill, it is necessary to evaluate the grindability of materials in advance.
