Characteristics of thermoplastic powder in an aqueous foam carrier for inhibiting spontaneous coal combustion

Abstract

For retarding self-heating of coal, a technique is described by applying a blend of thermoplastic and coal powder (TCP) in a foam carrier. The experimental study includes the behavior, microstructure and evolution of the foam, and the properties of the thermoplastic powder (TP) for inhibiting the spontaneous combustion of coal. It was found that increased TCP concentrations led to decreased foamability, with the detrimental effect on foamability levelling of at concentrations above 30wt.%. The low fusing temperature and high heat of fusion of the TP absorbed the heat generated by the self-heating coal at low temperatures. The liquid fused TP sealed gaps and cracks in the coal dust from oxygen entry. Infrared spectra showed that the TP suppressed alkyl and hydroxyl functional groups in the coal powder (CP) at higher temperatures. It was concluded that TP retarded self-heating in coal, and that the combined thermoplastic and coal powder in a foam carrier has the potential to prevent and control the spontaneous combustion of coal.