Using a horizontal batch dry bead mill newly developed by our company, talc raw material was ground in air, and its grinding performance and mechanochemical effect on the sample were evaluated from various perspectives. First, the average diameter of the ground product as a grinding performance decreases with the increase in grinding time or power source unit, reaching the submicron size. In addition, when mill operation is continued, talc changes fine particle aggregation and crystal structure change due to mechanochemical effects, and the phenomenon of detachment of the (OH) group around Mg in the crystals becomes remarkable. The flowability of the ground product is inhibited by the withdrawal of (OH) from the talc crystal, but this flowability is restored when it is dried. When the power source unit in the grinding approaches 3 kWh/kg, it asymptotes to the maximum value of 9% in the weight reduction percentage.

In the vacuum system of pneumatic conveying, the authors have proposed that a suction nozzle equipped with an injection pipe at the center would provide a highly dense, highly efficient method of transporting powder and particles. In this paper, we examined the effects of suction velocity and particle diameter on the loading ratio and the suction nozzle efficiency by attaching the injection port on the outer part of the suction nozzle. As a result, in the case of coarse particles within this experimental condition, the effect of suction velocity differs in both cases (the injection ports positioned at the center and outer part). This characteristic is explainable by the difference between fluidization phenomenon and aeration phenomenon. Under conditions that are not affected by the suction velocity, neither is affected by the particle diameter in both cases.

We conducted research aimed at developing a novel method for synthesis of MgF₂ hollow nanoparticles that is simpler than the conventional synthetic method. First, Mg(OH)₂ raw material nanoparticles were contact with hydrofluoric acid vapor in a gas-solid reactor at 473 K. As a result, the surfaces of the Mg(OH)₂ nanoparticles were fluorinated to obtain Mg(OH)₂-MgF₂ core-shell particles. Next, the MgF₂ hollow nanoparticles were synthesized by soaking the core-shell particles in 1.0 mol/L hydrochloric acid to dissolve only the Mg(OH)₂ core portion. We have succeeded in developing a method for synthesizing MgF₂ hollow nanoparticles with different MgF₂ shell thicknesses by controlling the surface fluorination reaction period of Mg(OH)₂ raw material nanoparticles.

Discrete element method (DEM) is well known as a promising approach for various particle processes such as separation and mixing. To establish effective these processes, it is essential to understand and control particle behavior. The present review gives brief descriptions of DEM and a wall boundary model based on singed distance functions. Two typical simulation results obtained from the DEM simulation are presented. One is density segregation associated with the stratification of particles between riffles on a shaking table. The other is particle mixing in a pot blender which rotates and swings simultaneously.