World Journal of Engineering Research and Technology

Aviv Hassid, Steffen Krzack and Haim Cohen*

ABSTRACT

Coals (Lignite and Bituminous), are a major source of energy worldwide and also its utilization is a source of environmental hazards. Upon exposure to the atmosphere post mining or during storage, these coals undergo exothermic LTO (Low Temperature Oxidation) process by atmospheric oxygen, that diminishes their calorific value and involves emission of toxic and flammable gases, endangering people and environment. It may lead to self-heating and potentially to fire eruptions if the temperature exceeds 300oC. One of the most hazardousreleased gases is H2, released in Bituminous coals but not in Lignite. Thus, unexplained explosions in underground coal mines where no accumulation of coal dust, methane, or carbon monoxide was reported (the common source of explosions), could stem from hydrogen accumulation. It was suggested that H2 release from coal hydroperoxides oxidation of formaldehyde produce unstable dioxirane which decomposes to hydrogen and carbon dioxide. The combined TGA (Thermal Gravimetric Analysis) /DSC (Differential Scanning Calorimetry) unit is a new and unique technique to follow the LTO process, it corroborated the suggested mechanism and provided critical insights into the thermal processes and mechanisms involved in the H2 generation via the LTO process. This emphasizes the importance of the TGA/DSC in studying complex chemical and thermal reactions.

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