STRUCTURAL FEATURES OF COALS OF A LOW STAGE OF METAMORPHISM WITH A TENDENCY TO SPONTANEOUS COMBUSTION.

The structural features of Donets coals of a low stage of metamorphism (C**d**a**f equals 75-80%) with and without a tendency to undergo spontaneous combustion have been investigated. The coals studied differed substantially in their physicochemical and structural parameters and were characterized by different elementary compositions, different degrees of aromaticity and structural orderedness of the organic matter, and different types of changes of the paramagnetic characteristics and of the nature of the paramagnetic centers. In coals with different tendencies to undergo spontaneous combustion, the organic sulfur was present in different forms. In the process of metamorphism, the structural differences are smoothed out.