At about 6.30 am local time (10.30 GMT) on Thursday 10 November 2011 miners at the Sizhuang Coal Mine near Qujing in Shizong County, Yunnan encountered a pocket of pressurized methane gas, causing an explosion that trapped 43 workers underground, according to the Yunnan Provincial Emergency Response Office. Twenty-one of the trapped miners have now been confirmed dead, and the State Administration of Work Safety and State Administration of Coal Mine Safety are overseeing efforts to rescue the remaining workers, in conjunction with the local fire service and emergency medical teams. These efforts are being hampered by the (flammable) gas remaining in the mine.
Map of Yunnan Province, showing the location of Quijing, to the east of Kunming, the state capital.
The Shizhuang Coal Mine has a poor safety record; in 2005 another gas explosion, followed by a fire, killed five workers and in November last year the Yunnan Administration of Coal Mine Safety revoked the mine's license on safety grounds, since when it has apparently operating illegally. China's coal industry has expanded rapidly as the country has industrialized, with production trebling in the last ten years, but this expansion has been plagued by safety problems, with Chinese mines gaining a reputation as the most dangerous in the world. However the authorities have been making efforts to remedy this situation, introducing safety regulations and closing (or at least attempting to close) mines that fail to comply. Annual deaths in Chinese mines have steadily fallen from 6995 in 2002 to 2433 in 2010, and while this is clearly still far too many (as is one) it is definitely progress.
The expansion in Chinese coal mining in the last 50 years.
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.
Rescue workers trying to identify dead miners at the Shizhuang Mine.
See also Disaster at Gleision Colliery, Godre'r Graig, West Glamorgan.