Statistical assessment of the indicator yield of volatile matter for forecasting hazardous properties of coal seams

Abstract

The article studies statistical models of the mass yield of volatile matter during the thermal decomposition of coals without air access with the aim (V^daf) with the aim of using this indicator to assess the degree of metamorphism (coalification) and forecast the hazardous properties of coal seams.

It is shown that the classification indicator of the yield of volatile matter, which is used in regulatory documents on the safe conduct of mining operations, is not sufficiently justified for these purposes. It was adopted in the absence of reliable knowledge about the structural and chemical composition of the organic part of the coal seam. The indicator V^daf characterizes the state of dry ash free organic (combustible) mass, and the composition of fossil coal, in addition, includes mineral impurities and moisture.

Purpose.To determine the probable relative errors in the measurement of absolute values indicator of the yield of volatile matter using statistical models. This will allow the indicator V^daf to be used with a given accuracy as the main classification criterion for the metamorphism (coalification) of coal seams to forecast their hazardous properties during mining operations.

The methodology is based on the use and statistical processing of experimental data from previous years, as well as on the formation of several sets of values V^daf, which have certain characteristic features. Further statistical analysis and assessment of these sets allows us to establish differences or similarities between statistical models of the criterion V^daf.

Results. It is shown that one of the significant factors of non-compliance with the normal law of distribution of the yield of volatile matter V^daf, as a random variable, is the different accuracy of its determination depending on the absolute values. The validity of using V^daf in engineering calculations of the forecast of hazardous properties of coal seams is proven only when its values are more than 15-20%.

For the first time, based on statistical models, ambiguous possible errors in determining the yield of volatile matter and the inexpediency of its use for forecasting are established. The need to use other indicators of the degree of metamorphism to improve the regulatory framework for safe mining operations, which directly reflect the content and properties of coal in the process of geological transformations, is proven.