Six miners have been confirmed dead and another three are missing following an explosion at a coal mine in the Municipality of El Zulia in the Norte de Santander Department of Colombia, on Friday 31 July 2020. Local authorities are investigating the cause of the explosion, which has not been confirmed at this time, but which is thought likely to have been related to a build-up of methane gas in the mine.
The approximate location of the 31 July 2020 El Zulia coal mine explosion. Google Maps.
Coal is formed when buried organic material, principally wood, in heated and pressurized, forcing off hydrogen and oxygen (i.e. water) and leaving more-or-less pure carbon. Methane is formed by the decay of organic material within the coal. There is typically little pore-space within coal, but the methane can be trapped in a liquid form under pressure. Some countries have started to extract this gas as a fuel in its own right. When this pressure is released suddenly, as by mining activity, then the methane turns back to a gas, expanding rapidly causing, an explosion. This is a bit like the pressure being released on a carbonated drink; the term 'explosion' does not necessarily imply fire in this context, although as methane is flammable this is quite likely.
Coal is also comprised more or less of pure carbon, and therefore reacts freely with oxygen (particularly when in dust form), to create carbon dioxide and (more-deadly) carbon dioxide, while at the same time depleting the supply of oxygen. This means that subterranean coal mines need good ventilation systems, and that fatalities can occur if these break down.
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