From woody biomass waste to biocoke: influence of the proportion of different tree components

This paper assesses the feasibility of producing a metallurgical quality charcoal (biocoke) through slow high temperature pyrolysis of woody biomass. The samples used for the experiments were different types of olive wood biomass from southern Spain as well as eucalyptus trunks from Uruguay. The experiments were conducted in a two-step process: a pyrolysis semi-batch reaction at 750 °C and 3 °C/min heating rate, followed by a second step of thermal treatment at 900 °C of the pyrolysis vapours. The type of raw material used plays an important role with respect to the amount and quality of the different pyrolysis products. With the operating conditions used, high solid (24–26 wt%) and gas yields (43–54 wt%) were obtained. The solids obtained (biocoke) fulfil the requirements of good metallurgical reducers. However, leaves and bark are detrimental to biocoke quality and should be avoided. Pyrolysis gases are rich in CO and hydrogen, whereas pyrolysis liquids are mainly composed of water.