Research progress on coal rock recognition technology based on electromagnetic waves

Applying electromagnetic waves to coal rock recognition can effectively improve the resolution capability of coal rock interfaces. Based on the coal rock interface model, the principle of using electromagnetic wave technology for coal rock recognition is explained. The paper introduces six methods for coal rock recognition, including γ–ray method, radar detection method, Terahertz signal method, electron resonance method, X-ray method, and infrared thermal imaging method. The principles of each method are analyzed, and the advantages and disadvantages of each method are compared as well as their applicability in coal mines underground. The research status of each method is analyzed in combination with practical industrial applications. The γ–ray method has significant advantages in detection distance, but it has radiation problems. It is basically eliminated. The radar detection method has the advantage of accurate recognition, but due to its severe signal attenuation and short detection distance, it is currently generally used for thickness measurement in thin coal seams. The Terahertz signal method has a short detection distance and can only be applied when the composition of the underground environment is stable. The electronic resonance method has severe signal attenuation, short detection distance, and high difficulty. It is currently basically abandoned in mines. The X-ray method has strong penetration and clear imaging, but it poses great harm. In the infrared thermal imaging method, the active infrared excitation method requires a lot of time to excite coal and rock, and there are significant safety hazards in high gas mine environments. Although the cutting flash temperature method takes a short time, it is difficult to achieve effective coal rock recognition for situations with multiple cutting teeth and complex layout. It is pointed out that the accuracy of electromagnetic wave coal rock recognition is determined by the echo information of electromagnetic waves, and further in-depth exploration should be carried out.