Charcoal as an Additive to Cokemaking: Co2 Reactivity Study

The present work aimed to investigate the influence of charcoal addition of different particle sizes on metallurgical coke reactivity. Thus, an eucalyptus charcoal was added to a prime American medium volatile coking coal in three amounts (3, 5 and 8%) and in two different particle size ranges (below 1 mm and between 3 and 4 mm). Charges of the individual coal and coal/charcoal blends were carbonized in a laboratorial scale coke oven (1 kg). The reactivity of the produced bio-cokes and reference coke were examined and compared using thermal gravimetric analysis in a CO2 atmosphere. Morphological analyses via optical and scanning electronic microscopies using samples from before and after reactivity experiments were also carried out. Charcoal addition showed a tendency to increase coke reactivity and lower the temperature at which carbon gasification started. Morphological observations confirmed that charcoal particles tend to be preferentially consumed compared with the coke matrix. However, bio-cokes produced with charcoal addition up to 3% for both particle sizes and up to 5% for the coarser particle size had a similar behavior in terms of CO2-reactivity as the reference coke. The effects of charcoal addition on coke texture and CO2 surface area appeared to justify the differences in coke reactivity.