Hematite (α-Fe₂O₃) nanoparticles were synthesized by a solvent-free homogeneous precipitation method using urea hydrolysis via dry mechanical treatment of urea and ferric nitrate nonahydrate for activation. This novel method consists of high-energy ball milling of the raw materials and subsequent heating of the activated liquid precursor, which can provide smaller-sized nanoparticles than conventional methods. The milling and heating conditions were systematically investigated in detail. It was found that the hematite formation can be promoted by milling ferric nitrate nonahydrate and urea simultaneously under dry conditions even when relatively gentle milling and heating treatments were employed. The hematite nanoparticles had a similar crystallite size and particle diameter regardless of the conditions. This method can contribute to large-scale environmentally-friendly synthesis of fine hematite nanoparticles.

The vibration mode of bend pipe and the choking prevention effect in dense-phase pneumatic conveying has been investigated experimentally. The vibration mode has been showed that it has four antinodes for longitudinal direction, and eight for pipe cross section as designed, and the vibration amplitude has increased as increasing the input voltage. Therefore, it is possible to adjust the vibration amplitude easily by changing the input voltage. Then, the frictional force between the packed bed and pipe wall has been increased with increasing particle diameter. However, it has been reduced with ultrasonic vibration in spite of kinds of particles and pipe diameter. This means the possibility of choking can be removed with ultrasonic vibration in bend pipe as well as in horizontal pipe.

A numerical study of the tableting process using a finite element method (FEM) is important to quantitatively understand the structural change inside the tablet and the mechanism of tableting failures such as capping, picking, lamination, and sticking. In the pharmaceutical field, the Drucker-Prager Cap (DPC) model is used most widely to demonstrate the mechanical behavior of the powder during tableting. The DPC model, however, cannot consider compaction speed, although the compaction speed has a large impact on the tablet strength and tableting failures. In our present study, a DPC–Perzyna model, which incorporates a visco-plastic behavior considering the compression speed, was proposed. Here, the DPC–Perzyna model was outlined and typical results obtained by the DPC–Perzyna model was presented.