A REVIEW PAPER ON MINE FIRE IN INDIA INTRODUCTION The problem of mine fire is as old as the history of the mine. The fires in coal mines are posing great hazard due to its increasing trend in the world and much more so in our country while mining of thick and thin seams under difficult geo-mining conditions. Due to fires in underground as well as surface mines, not only a considerable amount of resources is lost, but the entire mine environment is badly affected. So long as the fires are restricted to underground working only, these do not pose very serious threat because of their comparative case in tackling but once these become surface fire, impacts are very severe and the control measures are very difficult. Due to the increasing demand of coal in various sectors mainly the power sector (coking coal since it is trapped in fire), it has become necessary to analyze critically the fire problems in Indian coal mines. Jharia coalfield which is the store house of prime coking coal in India, has severely being affected by fires. The first mine fire was reported in this coalfield in 1916. Over the years, the number of such fires has increased to an alarming 70 odd locations covering a cumulative area of 17 sq. km. It is estimated that nearly 50 million tonnes of superior quality of coking coal have been lost and about 200 Mt of coal are blocked due to fire. Besides this, the mine fires are also polluting the environment by releasing large volume of CO and SO2 gases. Hence, precise mappings as well as monitoring of fires are pre-requisites for effective implementation of any action plan for firefighting operations.
CONCEPT OF MINE FIRES It is well known that mine fires are associated mostly with coal mines, though fires in pyrite mines and occasional timber fires in certain metal mines are not unknown. An analysis of the causes of coal mine fires reveal that they may start either from an open fire over the external mining agencies or originate due to very nature of coal. The propensity of coal liberating heat when coming in contact with oxygen of air and its poor thermal conductivity favors heat accumulation, may give rise to latter kind of heating. The former type of fire formed from external agencies is known as Exogenous Fires and the latter type i.e. due to self-heating characteristics of coal is called Endogenous Fires or Spontaneous Combustion. CAUSES OF MINE FIRES The exact cause of mine fires is till date unknown. Researchers proposed the following factors: (A) Geological factor (Seam thickness, seam gradient, caving characteristics, faulting, coal outbursts, friability, rider seams, depth of cover, geothermic gradient etc.). (B) Mining factors (mining methods, rate of advance, pillar conditions, roof conditions, packing, leakage, multi-seam working, coal losses, main-roads, worked-out areas, heat from machines, Ventilation pressure, differential barometric pressure, changes in humidity etc.).
A REVIEW PAPER ON MINE FIRE IN INDIA (C) Seam factors (rank, petrographic composition, temperature, available air, particle size, moisture, sulphur, interfering minerals, Physical properties, effect of previous oxidation, Heat due to earth movement, bacterial effect etc.) The importance of each factor is yet to be analyzed. Jharia coalfield result show that factors like shallow depth working, thick seam mining, and multi-seam contiguous panel working had created very complex situations which not only initiated the start of the fires but also speeded up their spread. The unscientific and slaughter mining had taken a toll of the reserves particularly before nationalization of Indian coal industry. FIRE IDENTIFICATION There are several methods through which fires can be detected in the underground mines. They are: a) Production of toxic gases: A fire produces CO, CO2 and reduces 2 degree content in the ventilating air. b) Thermal effect: The heating of ventilating current by the fire may cause thermal damage to the walls and...
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