A critical investigation into spontaneous combustion in coal storage bunkers

Abstract

In coal mining, spontaneous combustion can occur in many areas such as stockpiles, underground workings, waste dumps, coal faces, in-pit ramps and backfill areas. Spontaneous combustion has been defined as an oxidation reaction, which occurs without an external heat source. Although not limited to coal, the most significant hazard of spontaneous combustion is the fires that occur in coal mining operations around the world. These fires pose a serious risk to the safety of workers in the coal mines. This phenomenon also has an environmental impact, which can affect the quality of life for future generations. Extensive research work has been done and recorded about spontaneous combustion in coal stockpiles, dumps and coal faces, but very limited work has been conducted on raw coal storage bunkers. This study investigated the occurrence of spontaneous combustion in coal storage bunkers, and established that there is no single document available that addresses the problem adequately. Therefore, a need was identified to create a guideline with decision analyser steps to be able to arrive quickly at a possible solution to the problem. This work does not address spontaneous combustion in underground workings, waste dumps, stockpiles, coal faces, in-pit ramps and backfill areas. It was found that important factors affecting the possibility of SC occurring were the type of coal being supplied to the bunker, the mining practice with regard to the standing time of the loose cubic metres of coal on the mining benches, and the impact of the physical factors around the bunker. The information obtained could be of great significance when designing or trying to solve spontaneous combustion problems in raw coal storage bunkers. The guideline and decision analyser steps can be applied early in the phase of the project in order to minimise or eliminate similar mistakes made in the industry over the years.