Enhanced Combustion of Bituminous Coal and Semicoke Mixture by Ferric Oxide with Thermographic and Kinetic Analyses.

Abstract

We study the specific catalytic effect of the catalyst on the combustion process of pulverized coal of increasing the proportion of semicoke in the mixture of semicoke and bituminous coal, and reducing the cost of blast-furnace coal injection. A combination of thermogravimetric and kinetic analyses were used to study the catalytic effect of Fe2O3 on semicoke and bituminous coal, and to improve the amount of semicoke in the mixed coal powder of bituminous coal and semicoke. Experimental results showed that Fe2O3 had a catalytic effect on both semicoke and bituminous coal, but there were differences in the catalytic stages of the same catalyst for different pulverized coal types. The addition of 2 wt % Fe2O3 to semicoke and bituminous coal each led to the ignition temperature and maximal burning rate temperature of the semicoke decreasing, indicating that the catalyst promoted the precipitation of a volatile fraction from the semicoke. The maximal burning rate temperature and burnout temperature of the bituminous coal decreased, and maximal weight loss rate increased, indicating that the catalyst promoted the combustion of the fixed carbon of bituminous coal. The optimal proportioning amount of semicoke in the mixed coal powder without the addition of a catalyst was 25%. After adding 2 wt % Fe2O3, the proportional amount of semicoke increased by 10%. The addition of the catalyst resulted in even lower activation energy for the same conversion rate. When the conversion rate was in the ranges of 0.1–0.2 and 0.5–0.7, the activation energy decreased by 22% and 26%, respectively, compared with that without a catalyst. Fe2O3 promoted the combustion of bituminous coal and semicoke. This enhanced the combustion performance of the pulverized coal mix and increased the proportion of semicoke in the mix, which has certain guiding significance in reducing the cost of blast-furnace iron making.