Electromagnetic Emission From Fracture of Coal Saturated With Gas

ABSTRACT: A combined study of acoustic emission and electromagnetic emission of coal saturated with gases was performed in laboratory, in an attempt to characterize the electromagnetic behaviors of coal mass long and shortly before disastrous outbursts. It was proved experimentally that while saturated with gas, all coal samples, either normal or disturbed, emit both acoustic and electromagnetic pulses accompanying their deformation and final failure, regardless of gas species or saturating equilibrium pressure. Nevertheless, gases and their pressure do have substantial influence on the intensity of electromagnetic emission (EME). It was also discovered that the observed EME and acoustic emission occur synchronously, which indicates that they are phenomena initiated by the same events. EME activity intensifies while the loaded coal samples approach the final failure. The EME mechanism is discussed in terms of the fracture electrification and accelerating movement of charge. Results indicate the possibility of developing a portable system to forecast outbursts.