Thermogravimetric Study of the Effect of Particle Size on the Spontaneous Combustion of Indonesian Low Rank Coal

Abstract

Low-temperature oxidation of two Indonesian low rank coals was characterized by Thermogravimetric analysis (TGA). The effect of particle size on the spontaneous combustion of coal was examined. Coals were classified to-599+299, -299+249, -249-150, -150+76 and-76 μm size groups and through non-isothermal method scanned from 24 to 600°C at heating rate 5°C/min with air flow rate 50 mL/min. DTA thermogram shows that the transition temperatures decrease by decreasing the particle size. Furthermore, the weight loss increases by decreasing particle size. It is indicated that the propensity of coal to spontaneous combustion increase with decreasing particle size. The moisture loss activation energy and oxidation activation energy were calculated by an integral method using the Coats-Redfern formula. The results show that the propensity for spontaneous combustion of two coal samples (judged by the activation energy) increases by decreasing particle size.

Modeling of the Crossing Point Temperature Phenomenon in the Low-temperature Oxidation of Coal

“…Research and publications on the spontaneous combustion of coal have been reported by several researchers (Carras & Young, 1994;Nugroho et al, 1998;Sujanti et al, 1999;Nugroho et al, 2008;Saleh & Nugroho, 2013). Low-temperature oxidation leading to coal spontaneous combustion takes place when the heat generation rate of the coal pile exceeds the rate of heat dissipation to the environment.…”