Dependence of Surface Wettability and Filtration Capacity of Coals on the Degree of Metamorphism

The property of the coal surface to be wetted with various liquids is important for many technological processes of coal mining, sorting, processing, and transportation. In this work, we used the determination of the contact angle of the coal surface and the filtration of liquid through a layer of coal powder to characterize the wettability. The influence of changes in the chemical composition and porosity of coals in the series of their metamorphism on the wettability characteristics was estimated. It was shown that the wettability and filtration properties of coals exhibited an extreme dependence with a minimum at the middle stage of metamorphism.