The Effect of Presence of SiO2, Al2O3 and P2O5 on the Reduction Behaviour of Fe2O3 Nuggets with Coke Fines

A detailed investigation is made to study the effect of the presence of gangue materials like SiO2, Al2O3 and P2O5 on the reducibility of iron ores in the blast furnace and sponge iron/DRI plants. The shatter index and abrasion index are found to improve marginally with increased content of the gangue materials, though the improvement is not significant. The rate of reduction decreases with time, and interfacial chemical reaction is identified as the rate-controlling resistance. The apparent activation energy is determined from the slope of the plot \({1-(1-f)^{0.5 }}\) versus time, where f denotes the extent of reduction. At a high temperature (1373 K), a little deviation from linearity is observed, indicating greater contribution of diffusion. The apparent activation energy is found to vary between 125.82 and 149.49 kJ/mol for different composition of the nuggets. The presence of SiO2 and Al2O3 is found to reduce the apparent activation energy, E, while the presence of P2O5 increases the value of E. The average decrease in the apparent activation energy is found to be 1.63 and 1.33 kJ/mol per unit mass% increase in SiO2 and Al2O3, respectively, and the average increase in the apparent activation energy is 2.69 kJ/mol per unit mass% increase in P2O5.