流動下での乳糖粉体の粒径分布に及ぼす加重の影響

抄録

The purpose of the present study is to investigate the effect of loads applied to agitating powder beds on the particle size distribution. Lactose (JP) was used as a test powder bed and was processed under loads ranging from 6.24 to 41.9 g/cm² by a newly developed powder stress mixer. Particle size distribution and flowability of the processed powder was determined. Particle size distribution was determined by an image analysis system that involves optical microscopy. The internal friction coefficient was measured by a direct shear tester. It was found that at the light load (6.24 g/cm²), particles smaller than 74 μm increased and internal friction coefficient slightly increased with an increase of mixing time. At the heavy loads (29.2 g/cm² and 41.9 g/cm²), particles initially smaller than 74 μm became predominant, but further mix processing reduced them. Internal friction coefficient increased initially, but decreased with an increase of mixing time. Under the heavy loads, this is probably due to a quick increase of fine particles and their subsequent agglomeration to form larger particles. Furthermore, it was assumed that there was a critical fine particle size and critical quantity under which the physical properties of the powder bed change significantly.