Susceptibility of some WCL and NECL coal with respect to spontaneous heating

Abstract

The auto oxidation of coal ultimately leads to spontaneous combustion which is the major root cause for the disastrous of coal mine. It is a slow process and the heat evolved is carried away by air. This process of self heating of coal or other carbonaceous material resulting eventually in its ignition is termed as “spontaneous heating” or “auto oxidation”. The autooxidation of coal is a complex physico-chemical process which is accompanied by the absorption of oxygen, formation of coal oxygen complexes and their decomposition leading to the liberation of heat. Therefore the assessment for this combustion is very much necessary. It depends upon different characteristics and properties of coal. Coal mine fire is a major problem worldwide and has been a great concern both for the industry and researchers
in this field. Majority of fires existing today in different coalfields are mainly due to spontaneous combustion of coal. . It has been a major problem in the leading producing coal countries like Australia, India and China. Of the total coal inventory of 276.81 billion tonnes,
only 40 per cent, or 110 billion tonnes, falls into the proven category. Of this, around 55 billion tonnes is considered extractable, which the Coal Ministry says would last for about 100 years at the current production rate of 550 million tonnes. Coal India, the world's largest
coal miner, has said it will likely miss a government-set production target of 460.5 million tonnes for 2010/11 due to inadequate transport infrastructure, which has led to a stocks pileup. The spontaneous heating susceptibility of different coals varies over a wide range and it is important to assess their degree of proneness for taking preventive measures against the occurrence of fires to avoid loss of lives and property, sterilization of coal reserves and environmental pollution and raise concerns about safety and economic aspects of mining etc.
Although much research has been done on the subject, a proper assessment of the spontaneous heating susceptibility of coal needs to be done so that mine operators are notified well in advance and plan the working properly. Therefore, the determination of susceptibility of coals to spontaneous heating and their classification is essential to plan the production activities and optimise coal mine production within the incubation period. The project deals
with the assessment of various parameters of coal with the spontaneous heating tendency of coal. Ten coal samples were collected from western coalfield limited(WCL), of Coal India Limited and another six samples were collected from NECL .The project deals with susceptibility of different coal samples determined by experimental techniques. The intrinsic properties as well as susceptibility indices of the coal samples have historically been considered to be prediction of self heating liability. Most of the methods are based on the measurement of the oxidation rate and ignition temperature. The propensity of different coal to self heating has been studied in the laboratory were determined by experimental techniques: bomb caloriemeter ,Differential thermal analysis, olpinski index ,proximate analysis,wet oxidation potential.