Characterization of noise generated by mining equipment in an underground room and pillar coal mine

摘要

Noise generated by mining equipment in underground room and pillar coal mines isrncomprised mainly from separate spectrums of three major sources: A) Continuous MiningrnMachines (CMM), B) Roof Bolters, and C) Haulage Equipment (cars/vehicles transportingrnpersonnel and/or coal). Spectrums from each of these major sources are also comprisedrnfrom very well defined noise sub spectrums generated by individual components of thernmining equipment. Noise level measurements are often presented in dBA (“A” weightedrnSound Pressure Level - SPL) with frequency ranges from 100 Hz up to 10 kHz. Detailedrnanalysis of mine noise shows that there is a relatively large component of below 100 Hz asrnwell as above 10 kHz. Use of the “A” weighted characteristic is not feasible to measure SPLrnin these frequency ranges. Thus, the “C” weighted (or linear) characteristic has been usedrnin our investigations. It has been observed that the CMM’s cutter head, interacting withrnthe coal seam using considerable thrust force and torque to extract and move coal andrnsometimes the rock above and below it, generates large amounts of low frequency noisern(LFN). Also, during the coal extraction process, very low frequency noise (on the edge ofrnair vibration) with high amplitude had been observed. This noise can be described as arntypical LFN modulated by very low frequency, (often around or less than one hertz) andrnperceived as a flutter or “rambling” noise, or the product of a biting (superposition) ofrnsimilar LFN spectrums. This LFN noise travels long distances in the underground minernstructure. Roof bolters generate a noise spectrum with a very high frequency (above 10rnkHz) component. This paper presents and discusses noise spectra’s in frequency and timerndomains generated by underground mining equipment. These data are useful forrnequipment operating personnel and their supervisors and managers to properly schedulernand control coal extraction and transportation processes for minimizing noise exposure.