Study of hierarchical structure of fossil coals by small-angle scattering of thermal neutrons

Abstract

The problem of safety and prevention of sudden gas and rock outbursts during coal mining remains relevant today. One of the factors characterizing the outburst hazard of a coal seam is the structure and petrographic composition of coal. Then we aimed to use small-angle neutron scattering (SANS) to characterize 27 coals to draw relationships between SANS results and seam outburst behavior and other characteristics of coals.Non-destructive method such as SANS of thermal neutrons makes it possible to study the structure in the volume of the samples. Fractal dimensions and their correlation with the specific surface of the pore space, the degree of coalification, the depth of coal-seam and the propensity of the seam to coal-gas-outbursts are determined for coals of the Donets Basin.The outburst hazardous coals were found to have the following characteristics: the surface fractal dimension Ds close to 2.9–3.0 or the mass fractal that are formed by conglomerates of various mineral inclusions containing iron and sulfur. Contrary to this case less outburst-prone coal structure is characterized by more “smooth” pore space surfaces at Ds < 2.9 and by a higher content of silicon and aluminum.