Electromagnetic response of outburst-prone coal

Electromagnetic response of coal is a phenomenon in which the emission rate of gas from coal is changed by an electromagnetic field. To help further t he knowledge of coal and gas outbursts and explore effective measures for o utburst prevention and control, the electromagnetic response of a variety o f coals was investigated and related to coals' outburst proneness. Laborato ry research was conducted using an experimental system composed of a differ ential pressure gauge and an electromagnetic field generator. Experimental results show that a substantial change in the rate of gas emission occurred when an electromagnetic field was applied to coal particles saturated with gas under a pressure of 0.1 MPa. The amount of change observed in outburst -prone coal is greater than that associated with non-outburst-prone coal. B ased on the experimental results, an electromagnetic emission model for out bursts is put forward. which argues that in typical coal and gas outburst, electromagnetic emission plays an important role in the trigger and develop ment stages, helping destroy the coal mass and enabling rapid energy releas e by gas expansion. It is also possible to use an imposed electromagnetic f ield to improve gas drainage efficiency of outburst-prone coal seams. (C) 2 001 Elsevier Science B.V. All rights reserved.