Investigation of the thermal behavior of Pinus wood pellets during torrefaction for application in metallurgical processes

The aim of this study is to investigate the thermal behavior of Pinus wood pellets during torrefaction under different operational conditions, as well as to evaluate the potential application of the torrefied product in metallurgical processes. Torrefaction tests were carried out in an oxidizing atmosphere (245 °C) and in an inert atmosphere (270 and 290 °C) at residence times of 15 and 60 min. The results of torrefaction in inert atmosphere were also statistically evaluated. To evaluate the potential application of torrefied biomass in metallurgical processes, reactivity tests with CO2 were performed in the temperature range of 200–1000 °C. The results showed that high torrefaction temperature and residence time decreased the mass yield. Statistical analysis showed the possibility of combining high temperatures with low residence times, or vice versa, to obtain satisfactory mass yields. The experimental results showed the highest reactivity for the torrefied biomass obtained in an inert atmosphere, at 290 °C and 60 min. However, considering the mass yield and reactivity with CO2, the best torrefaction conditions for biomass with potential application in metallurgical processes were in an inert atmosphere, at 290 °C and a residence time of 15 min.