Performance regulation of biomass-derived coke for metallurgical applications based on the fractional utilization of biomass pyrolysis oil

The high reactivity and low mechanical strength of conventional biochar and biocoke are the main factors limiting their addition rate to substitute the coal coke in metallurgical applications. In this work, coupled with the fractional utilization of biomass pyrolysis oil, a novel regulation method of biocoke without exogenous substance has been proposed and comprehensively studied. Acidic light oil and high-viscosity heavy oil were respectively used for acid leaching and briquetting pretreatments of biochar before the final coking. The addition of 20 wt% heavy oil has increased the biocoke yield by 16.6 % and improved the compressive strength of biocoke to 5.3 MPa, approaching that of coal coke. In addition, the combustion and gasification reactivity of biocoke was strongly decreased due to the effective removal of 41.6 % alkali and alkaline earth metal by light-oil leaching and the increased particle size through briquetting. Through further adding re-pyrolysis of briquetted biochar before coking to control the release rate of heavy oil, lower combustion reactivity and higher gasification reactivity of biocoke were achieved compared to coal coke. Finally, the optimized biocoke has 38.3 % coke reactivity index and 40.2 % coke strength after reaction, closing gap with metallurgical coke, enhancing replacement potential.