Burnt coal field detection via magnetic exploration

The spontaneous combustion of coal seams is a common problem in coal-producing countries. Coal fires cause wastage of coal resources and land subsidence. Moreover, they pollute the environment by releasing toxic gases. Knowledge of the location of fire sources is critical for coal fire monitoring and environmental remediation. Magnetic data were collected from an open-pit coal mine in the Ordos Basin, an important coal-bearing basin in Northern China. Multiple quality control methods were adopted to ensure data quality. This study first analyzed how coal fires cause magnetic anomalies and then reinterpreted how different magnetic anomaly features indicate coal fires which may help refine the correspondence between magnetic anomalies and coal fire regions. In addition, these analyses indicate that magnetic anomalies in coal mines can indicate the distribution of coal fires indirectly, because magnetic exploration target the overburden rather than the coal fires. Furthermore, magnetic correlation imaging was applied to locate the depth of the burnt rocks, and their elevation ranges were given based on the imaging results. Some observations support the results of the analysis and calculations in this paper.