On the Issue of Establishing the Stages of Coal Metamorphism for Predicting the Hazardous Properties of Coal Seams

Abstract

The characteristic stages of metamorphic transformations of mines are established according to the increase in the elemental content of carbon and changes in other components of organic matter. Stages of metamorphism transformations with an average carbon content of more than 93.6% can significantly differ in properties due to the unpredictability of the ratio between the components of organic matter. At these stages, even a minimal difference between the components can be the reason for the emergence of new properties of the coal seams. As the influence of the processes of metamorphism increases, the boundaries of the stages, determined by the percentage of carbon, narrow. The established stages of the transformation of reservoirs in terms of the individual proportion of the components in carbonization practically do not differ from the boundaries of the stages determined by the elemental composition of organic matter. It is noted that the average carbon content at the stages of seam metamorphism, determined by the yield of coke, in most cases does not coincide with the ranges of changes in the average carbon content, established by the individual content of the components or their share in carbonization. The inconsistency of the boundaries in the stages of seam metamorphism makes it unacceptable to use the coke yield as the main criterion for assessing the conversion of coal and even more so the manifestation of hazardous properties of coal seams.

Keywords

• coal, metamorphism, elemental composition, coal seams, hazardous properties