Mechanism of measuring ash with low-energy gamma rays for equal coal seam thickness

Abstract

ABSTRACT Considering the issues related to significant fluctuations and errors in the measured data of the dual-energy gamma-ray online ash analyzer caused by various external factors, this study investigates the impact of factors such as the distance between the detector and the radioactive source, coal seam thickness, moisture content, and particle size range on ash measurements. Additionally, a novel low-energy gamma-ray online ash measurement device is proposed, which ensures uniform coal seam thickness. By utilizing this device, the coal samples subjected to measurement exhibit characteristics such as small particle size, a narrow range of particle sizes, a smooth coal flow surface, consistent coal flow density, a fixed distance between the coal seam and the detector surface, and constant coal seam thickness. These conditions collectively provide optimal circumstances for accurate low-energy gamma-ray ash content measurement. Experimental results indicate that during the separation of Suntuan: Tongting raw coal, the average discrepancy between the measured ash content and the assay ash content was only 0.33%, and the standard deviation of the measured ash content was significantly lower than that of the assay ash content. Specifically, when separating Suntuan: Tongting raw coal, the standard deviation reached its minimum at 0.16%. Comparatively, the low-energy gamma-ray online ash measurement device outperforms the dual-energy gamma-ray online ash analyzer, exhibiting enhanced accuracy and stability in ash measurements, thereby better fulfilling the requirements of daily production.