Recovery of SiC powder from sintered DPF using hydrothermal treatment combined with ball-milling technique

In the present work, hydrothermal treatment combined with ball-milling technique (HTBT) was attempted to recover SiC powder from bulk sintered DPF. Various parameters including the material and size of the milling-ball, the type of the solvent medium, the rotation speed, the ratio of solvent/DPF, the treatment temperature and time were optimized. The pulverization rate, impurity content and the particle size of the recovered SiC powder were investigated to assess the effect of HTBT. Dilute HF solution was selected as the main solvent and SiC milling-ball was the most suitable for pulverization of the sintered DPF. The rotation speed played a significant role for the pulverization rate and more than 90% of bulk sintered DPF was recovered as SiC powder using SiC balls (5 mm in diameter) in the mixed aqueous solutions of HF (0.05 mol/dm3) and H2O2 (0.25 mol/dm3) with rotation speed ≥ 275 rpm and solvent/DPF = 1.5 at 200°C after 20 h HTBT . Generally the average grain size of the recovered SiC powder was less than 1.5 μm and decreased with the extended treatment time and the increased rotation speed. The result of purity analysis showed that the recovered SiC powder totally met the demand of the raw SiC powder for DPF production under the optimized conditions.