Effect of the addition of waste sawdust on thermoplastic properties of a coal

Abstract

Three different sawdusts obtained as wastes from the furniture and flooring industry were selected to study their influence on coal thermoplastic properties. A bituminous coal with a high volatile matter content was chosen as base coal. To investigate the effect of reducing the oxygen content of the sawdusts upon the coal’s properties, the sawdusts were heat treated to 250 °C. Blends of the coal with the three as-received and then heat-treated sawdusts were tested. In order to gain a better insight into the subject, the sawdusts were pyrolyzed at 400 °C to determine the effect of the resulting char and bio-oil upon the plastic properties of the base coal. The Gieseler curves corresponding to the coal–sawdust blends were calculated from the curves corresponding to the coal-char and coal-bio-oil blends. The errors obtained were in all six cases lower than the repeatability allowed by the ASTM standard for the Gieseler test. Considering that the effect of the additives is the sum of both chemical and physical effects, it was possible to evaluate the contribution of each of these to the reduction of coal fluidity. In all cases it was found that the physical effects were more important. The textural properties of the chars obtained at 400 °C from the biomass were found to be important for determining the influence of biomass on the coal fluidity.