procedure was repeated as the oven temperature was
increased at intervals of 20–50 K. Included in the figure
are also the data on bituminous coal obtained by von
Raczeck [23] using a similar experimental procedure. The
results show that the devolatilization of the coffee (mbuni
and parchment) husks and the wood chips starts (upon
completion of drying) at low temperatures of 160–2008C.
Around 2008C, the devolatilization is rapid and significant
weight loss is recorded whereas above 5008C, the weight
remains more or less constant. For the bituminous coal,
devolatilization starts at 350–4008C and a constant weight
loss is observed at temperatures higher than 6508C, whereas
the coffee charcoal exhibits a characteristic between coal
and the biomass. Similar results were obtained for rice
husks of Guyanese origin, analysed in a TGA [24]. The
weight loss time histories of the 1.0 mg rice husk samples
were recorded on a Bascom-Turner microprocessor. The
evolution of the volatiles was observed at around 190–
3008C depending on the heating rate and at around 5308C,
no further changes in weight were observed. The results of
these experiments show that complete devolatilization of the
agricultural residues as well as the combustion of the char