Study on pore characteristics of lean coal at different temperature by CT technology

To investigate the micro-pores development of coal under high temperature, experimental studies were performed with fine specimen of lean coal as small as 1 mm in diameter through a micro-CT system mu CT225kVFCB. Through statistic analysis, some fundamental characteristics of pores development are discovered with temperature rising from 1.8 degrees C to 600 degrees C It was demonstrated that the thermal cracking temperature threshold is 300 degrees C for lean coal. From room temperature to 300 degrees C the porosity of coal increased by 0. 5 times. Fractal analysis demonstrates that, most of the original regular small pores become connected and gradually grow to irregular and larger pores as the effect of thermal expansion and cracking with temperature rising. Above 400 degrees C, the size of the pores becomes smaller again while the pore number increases with the complicated effect of pyrolysis of the coal. The study is significant for insight into the micro-structure development of coal under high temperature.