The Jharia coalfield in Bihar is an exclusive storehouse of prime coke coal in the country, consisting of 23 large underground and nine large open cast mines. The mining activities in these coalfields started in 1894 and had really intensified in 1925. The history of coal-mine fire in Jharia coalfield can be traced back to 1916 when the first fire was detected. At present, more than 70 mine fires are reported from this region.
Coal, a non-renewable source of energy, is found in several parts of the world. The coal layers are mined by two methods: open cast mining and underground mining. Coal is formed from organic matter with a high carbon content, which when exposed to certain conditions (temperature, moisture, oxygen etc.) tends to ignite/ burn spontaneously at rather low temperatures. This may occur naturally or the combustion process may be triggered by other causes.
However, once a coal seam catches fire, and efforts to stop it an early stage fail, it may continue to burn for tens to hundreds of years, depending primarily on the availability of coal and oxygen. Coal fires have occurred in nearly all parts of the world like India, the US, Indonesia, South Africa, Australia, China, Germany and many other countries. However, the nature and magnitude of the problem differs from country to country. In India, the fire in the Jharia coalfield has mainly been due to unscientific mining and extraction of coal in the past.
Fires may occur in coal layers that are exposed to the surface of the earth or areas close to it. These are visible to the naked eye. Also, fires erupt in the underground seams, which have large cracks that serve as channels for oxygen to the burning coal. The main cause of natural coal fires are lightening, forest fires, bush fires, etc. Among human causes are accidents, negligent acts, domestic fires, lighting fires in abandoned underground mines for heating or distilling alcohol etc. Besides, burning away of an important energy resource, it creates problems for exploitation of coal, poses danger to humankind, raises the temperature of the area, and when present underground, can cause land to subside.
The pollution caused by these fires affects air, water, and land. Smoke, from these fires contains poisonous gases such as oxides and dioxides of carbon, nitrogen and sulphur, which along with particulate matter are the causes of several lung and skin diseases. High levels of suspended particulate matter increase respiratory diseases such as chronic bronchitis and asthma, while the gases contribute to global warming besides causing health hazards to the exposed population. Methane emission from coal mining depends on the mining methods, depth of coal mining, coal quality and entrapped gas content in the coal seams. These fires also pollute water by contaminating it and increasing its acidity, which is due to a certain percentage of sulphur that is present in coal. These fires lead to degradation of land and does not allow any vegetation to grow in the area.
The measures for controlling coal mine fires, in the case of Jharia coalfields, include bull dozing, leveling and covering with soil to prevent the entry of oxygen and to stabilize the land for vegetation. Fire fighting in this area requires relocation of a large population, which poses to be a bigger problem than the actual fire fighting operations.