Measurement of Electromagnetic Field Component Emissions as a Precursor of Emerging Hazard in Coal Mines

Abstract

The article presents the results of research concerning electromagnetic (EM) field emitted by rocks during the process of their destruction. The paper describes a measuring stand designed for subjecting rock samples to axial crushing. During the destruction of rock samples, both components of the electromagnetic field emitted by the rock were recorded. The paper presents the results of research on hard coal samples, presenting the obtained time domain waveforms and frequency spectrum of the emitted EM field components. Further potential uses of tests concerned with EM emitted by rocks are determined. Applications registering EM field in mine environments may provide an early mine collapse warnings.

Autonomous Instrumentation for Measuring Electromagnetic Radiation from Rocks in Mine Conditions—A Functional Analysis

“…In order to compensate for unevenness of the specimens and uniform distribution of compressive forces, soft wood was placed between the tested specimen and the jaws of the press. The computer on the measuring stand recorded the amplitudes of the obtained signals of the EM field components [27]. In the further analysis, the spectral distribution of the signals was established.…”

“…These statements are preceded by laboratory tests of electromagnetic field emissions from rock samples subjected to destructive axial pressure [25,26]. For different types of rock samples tested, frequency bands of increased EM emission can be distinguished, and the time courses of EM field components have the character of fading pulses whose frequency spectrum is continuous [27,28].…”

“…sors 2022, 21, x FOR PEER REVIEW field components[27]. In the further analysis, the spectral distribution established.…”

Bulletin of the Polish Academy of Sciences: Technical Sciences

“…In order to compensate for the unevenness of the samples and evenly distribute the compressive forces, soft wood was placed between the test sample and the jaws of the press. The computer on the test stand recorded the amplitudes of the obtained signals of the EM field components [13]. The spectral distribution of the signals was further analyzed.…”

“…In each case, frequency bands of enhanced EM emission can be distinguished for each rock sample tested [13]. As a result of an increase in the internal mechanical stresses of the rock mass, spontaneous emission of weak EM fields occurs.…”