Torrefaction of biomass wastes: Characterization as potential reducing agents for metallurgical industries

Torrefaction of low-cost poplar biomass was evaluated in this work for manufacturing bio-coal materials as reducing agents for metallurgical applications. Two different severity conditions were used in the multiple hearth furnace of the torrefaction pilot-plant CENTORRE (at an average flow rate of 45 kg h^-1 in dry basis): I) 300°C; ii) 350°C, with a residence time of 45 min, respectively. The raw and torrefied biomasses have been characterized using thermal-gravimetric and elemental analyses (C, H, N, S, O). The kinetic profiles were evaluated using the pseudo-first order rate equation (PFORE). An increase of the carbon/oxygen ratio was obtained as a result of the torrefaction severities. The greater mass losses were evidently obtained at higher temperatures (52% at 300°C, and 67% at 350°C). Additionally, the torrefaction process allows the storage of the feedstock for longer time; it reduces the energy consumption for grinding, and enhances the friability of the biomass for large-scale utilization in metallurgical furnaces.

Abbreviations: CENTORRE: Multiple hearth furnace; PFORE: Pseudo-first order rate equation. © 2021, ETA-Florence Renewable Energies. All rights reserved.