The reduction kinetics of hematite particles in H2 and CO atmospheres

The reduction characteristics of hematite particles (i.e., Fe2O3) in H-2 and CO atmospheres were experimentally investigated using isothermal thermo-gravimetric analysis (TGA). The mean diameter of the hematite powder (d(p,m)) was about 0.74 mu m. A mixture of pure hydrogen (H-2) and carbon monoxide (CO) gases was used as a reductant at a fixed flow rate of 0.1 lpm. Nitrogen (N-2) was used as a diluent gas to control the mole fraction of the reductive mixture. The temperature for hematite particle reduction in the TGA (T-R) was varied from 550 to 1300 degrees 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 T-R = 1050 and 1300 degrees 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 H-2 atmosphere and 2.3 kJ/mol for a CO atmosphere at T-R = 800-1300 degrees C. (C) 2017 Elsevier Ltd. All rights reserved.