Instrumental method for nuclear-physical determination of coal quality

Abstract

The invention relates to nuclear physics methods for coal analysis. The objective of the invention is to improve the accuracy of ash content determination under conditions of variable coal composition. An instrumental method for nuclear-physical determination of coal quality, consisting of the selection of point samples and their preparation, characterized in that additional primary samples are taken depending on the mass of the coal batch being tested and its size, the combined sample is crushed to a class of -10 mm, averaged and the variation in coal quality (heterogeneity) is calculated based on the value of the standard deviation of ash content in laboratory samples of class -10 mm, weighing 6 kg, the prepared representative sample is uniformly irradiated over the entire surface with gamma radiation with energy E0, ensuring the depth of investigation h according to the condition h≥3·dmax, the intensity of scattered gamma radiation is measured with optimal probe parameters (energy of scattered gamma radiation, probe length, angular and collimation characteristics, probe-surface distance), providing maximum relative sensitivity to ash content SA and minimum error in determining ash content σA depending on the calculated variation in coal quality σН (heterogeneity error) at the sample preparation stage according to the condition (σН / SA=σA=min), and the ash content of coal in prepared laboratory samples of class – 10 mm is determined by the intensity of scattered gamma radiation measured at the selected energy E0 and the achieved sensitivity to ash content SA. The technical result of the invention consists in increasing the accuracy of determining the ash content of coal due to the additional finding of the quality variation of laboratory samples of class -10 mm, the selection of the optimal energy E0 taking into account the size of the coal, the depth of the study and the parameters of the probe, ensuring the maximum sensitivity SA and the minimum error σA depending on the calculated quality variation σH.