Effect of H2 addition on the preparation of ZrO2 powder from zircon (ZrSiO4) using a plasma torch.

In this study, the plasma torch is utilized for the preparation of highly pure ZrO 2 from zircon (ZrSiO 4). The incorporation of H 2 into the discharge gas Ar improves the plasma physical parameters and serves as a reducing agent to promote the irreversibility of the pyrolysis reaction of ZrSiO 4. ZrSiO 4 powder is fed internally into a DC arc plasma torch through a powder feeder device. The DC torch generates thermal plasma that can fully heat all the ZrSiO 4 within a short period for pyrolysis, extraction, and separation, eventually producing high-purity ZrO 2. According to the results, the addition of H 2 to the working gas increases the material temperature in the flame by increasing the plasma temperature, thereby promoting the pyrolysis of ZrSiO 4. The temperature of the material is 2500–2600 °C, which is higher than the boiling point of the pyrolysis product SiO 2 while maintaining the high melting points of ZrSiO 4 and ZrO 2. Furthermore, H 2 plasma acts as a reducing agent in the pyrolysis reaction, where it combines with the O of the product to prevent the reversibility of the pyrolysis reaction of ZrSiO 4 and retains only ZrO 2. [ABSTRACT FROM AUTHOR]