Kinetics of Voluminal Reduction of Chromium Ore Fines Containing Coal by Microwave Heating

The kinetics of voluminal reduction of chromium ore fines containing coal (COFCC) by microwave heating was studied. When the molar ratio of carbon to oxygen was 0.84 and that of CaO to SiO₂ was 0.39 in COFCC, the temperature-rising rate of COFCC by microwave heating was 62.5 °C/min, 68.75 °C/min, 70.59 °C/min, and 72.22 °C/min at 1000 °C, 1100 °C, 1200 °C, and 1300 °C, respectively. The results show that the voluminal reduction of COFCC by microwave heating at solid-solid phase is first order reaction, with the apparent activation energy of 51.480 kj/mol. The limiting step of reaction rate for the overall reaction is the mass transfer of CO in the reduced product layer between dielectric particles of chromium ore and coal.