Processes involving biomass oxidation are considered to be CO₂-neutral, since the replenishment 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, could be a strategy for the reduction of CO₂ emissions in the overall iron-making process.

J.A. MacPhee et al. from the CANMET Energy Technology Centre in Ottawa, Canada have reported 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 more calcium than the coals used. However, carefully sized fractions of coarse charcoal (-3/8 +1/4 inch) produced much higher-quality coke, possibly the result of a different dispersion of the charcoal mineral components. This points the way towards further work in this area.

Fuel Processing Technology, Volume 90, Issue 1, January 2009, Pages 16–20.
DOI: 10.1016/j.fuproc.2008.07.007