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

► We studied the effect of waste sawdusts on coal thermoplastic properties. ► The sawdusts was heat-treated to reduce their oxygen content. ► The effect of heat-treated sawdusts was even more deleterious than that of the as received sawdusts. ► The contribution of chemical and physical factors to the reduction of coal fluidity was evaluated. ► In all cases it was found that the physical effects were more important.