Possible CO2 mitigation via addition of charcoal to coking coal blends

Processes involving biomass oxidation are considered to be CO2 neutral since the replenishing of the biomass by normal growth will remove CO2 from the atmosphere. Thus the use of charcoal in the production of metallurgical coke, to be used as a reducing agent in the formation of iron, would be a strategy for the reduction of CO2 in the overall ironmaking process. This paper describes experimental attempts to produce industrial grade coke from coking coal blends to which are added amounts of charcoal up to 10%. Coking experiments were carried out partly in a 30 lb coke oven and partly in a sole heated oven. The influence of blend composition, heating rates and charcoal particle size was investigated. Cokes made using fine charcoal addition (-60 mesh) were considerably weaker than cokes made from the base blend. This is interpreted to be the effect of the ash constituents in the charcoal which, among other things, contains much higher calcium than the coals used. However, carefully sized fractions of coarse charcoal (-3/8 + 1/4 in) produced much higher quality coke, possibly the result of a different dispersion of the charcoal mineral components. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.