The reduction kinetics of hematite particles in H2 and CO atmospheres

The reduction characteristics of hematite particles (i.e., Fe2O3) in H2 and CO atmospheres were experimentally investigated using isothermal thermo-gravimetric analysis (TGA). The mean diameter of the hematite powder (dP,m) was about 0.74 μm. A mixture of pure hydrogen (H2) and carbon monoxide (CO) gases was used as a reductant at a fixed flow rate of 0.1 lpm. Nitrogen (N2) was used as a diluent gas to control the mole fraction of the reductive mixture. The temperature for hematite particle reduction in the TGA (TR) was varied from 550 to 1300 °C. Experimental results showed an increase in the reduction rate of iron oxide particles with an increase in the reductant mole fraction and surrounding temperature. The reduced particles displayed a sticking behavior at TR = 1050 and 1300 °C. The phenomenon of particle swelling was observed in a CO atmosphere. The global activation energy of the iron oxide particles was measured as 43.5 kJ/mol for a H2 atmosphere and 2.3 kJ/mol for a CO atmosphere at TR = 800-1300 °C.