Research on the development of rock-coal interface monitor in top-coal caving mining

摘要

The strong radioactivity such as shale stone is more than 10 times higher than that of coal and even the medium radioactivity such as pelitic sandstone is 5 times higher than that of coal. Therefore, the natural gamma rays in the coal-rock mixture mainly comes from the refuse and it is feasible to make sure the rate of the refuse in coal-rock mixture by means of detecting the content of natural gamma rays. The detecting mechanism of rock-coal interface by natural gamma rays in top-coal drawing process was put forward. The mathematics relationship between the rate of rock in the drawn coal-rock mixture and the radiation intensity of natural gamma rays was established. In accordance with the principle, a detection monitor for rock-coal interface in top-coal drawing process was designed. The hardware frame construction and the software function of the detection monitor were analyzed. At the same time, several ways to improve its measure precision of top-coal drawing degree were found out. The results of ground test established by the author indicate that it is effective to judge top-coal drawing degree with diameter 100mm crystal detection monitor.