Self-Heating Risk of Coals and Metal Powders: A Comparison

The self-heating risk of four coal samples (two bituminous and two subbituminous) and five metal powder samples (four industrial and one laboratory-prepared) were studied calorimetrically using oxidation heat at 30 °C. All of the samples were measured in fresh (as-received), vacuum-dried and wetted states. The heat effects of fresh and/or dried coals were found to be significantly higher than those of the metals. On the other hand, wetting the samples markedly increased the oxidation heat mainly of the metals, making their oxidation potential comparable to or even exceeding that of the subbituminous coals. As a practical consequence, a comprehensive index to assess the self-heating risk of the materials in respect to both their oxidation ability and the effect of moisture is proposed.