The effect of temperature and compression during pyrolysis on the density of charcoal made from Australian eucalypt wood

Charcoal produced from sustainably grown biomass can be used to reduce the net CO2 emissions from iron and steel making operations. However careful control of pyrolysis conditions is required to produce charcoal with the necessary properties to optimise substitution for coal and coke in specific applications. The density of charcoal is an important property to control in order to minimise transport and handling costs as well as control of charcoal reactivity and strength. In this work the density of charcoal has been increased through compression of Blackbutt wood chips during pyrolysis. The true density of charcoal prepared under compression of 0.5 MPa and at a heating rate of 2 degrees C/min was found to increase with pyrolysis temperature, especially at temperatures higher than 450 degrees C. This increase in true density is likely to be due to restructuring of the graphitic structure at high temperatures. The true density of charcoal was found to be independent of compressive pressure during pyrolysis (0.056-4.0 MPa). The porosity of charcoal increased linearly with pyrolysis temperature and ranged from 0.24 at 300 degrees C to about 0.46 at 700 degrees C. The apparent density of charcoal prepared under a compressive pressure of 0.5 MPa was about 1000 kg/m(3) and had minimum between 400 and 600 degrees C. This is similar to the apparent density of metallurgical coke. The results suggest that specially prepared charcoal could be a viable substitute for coal and coke in steelmaking applications which require a dense carbon product. (C) 2015 Elsevier Ltd. All rights reserved.