Preparation and combustion behavior of carbon-based synfuel from biomass/coal/CaO by co-carbonization process

An environmentally friendly and low-cost co-carbonization technology has been reported as an effective route for the preparation of carbon-based synfuel for sintering processes employed in the steel industry, in which loaded CaO catalysts promote the synergistic role between sawdust (SD) and bituminous coal (BC). In this work, a series of experiments were conducted to research the effects of the co-carbonization temperature, co-carbonization holding time and addition amount of CaO on synfuel. Finally, a co-carbonization temperature of 550 °C, a co-carbonization holding time of 30 min, and the added amount of CaO at 4 wt% were reasonable preparation conditions based on the biomass/coal of 4/6. According to the above experimental parameters, the solids yield, bulk density and heat value of SD/BC synfuel were 61.07%, 403 kg m −3 and 27.82 MJ kg −1 , respectively. These results showed that adding CaO increases the order and density of synfuel microcrystals. For the surface structure, the addition of CaO could improve the content of aromatic C C and C–O, whereas the content of carbonyl C O decreased in the carbonization process, which demonstrated that the addition of CaO could improve transformation of the graphite-like structure. Additionally, SD/BC synfuel loaded with CaO exhibited a rougher surface and larger pores compared to that without CaO loading, and the number of pores decreased because the formation of CaCO 3 coated the synfuel surface. The above indicators of carbon-based synfuel obtained from this study agree with the practical requirements of sintering operations. This work reveals the mechanism of biomass/coal and CaO interaction on the preparation of carbon-based synfuel.