Steeping Coal in Lime Solution to Modify the Surface Wettability and Mineralization

This research is part of a cycle devoted to establishing scientific principles for the control of coal’s physicochemical state in the exploitation of beds using injective grouting of cracks by active suspensions. The deactivating mixtures are filtrates of lime suspensions with different concentrations. The samples to which these suspensions are applied consist of long-flame coal of limited metamorphic development, which is highly susceptible to oxidation and self-ignition. Change in its surface wettability is assessed by liquid filtration through a layer of coal powder in a soil model. Steeping coal with suspension filtrates of pH 12.5 is found to produce uniform passivation of the coal surface, with change in its oxidative properties. This is accompanied by increase in wettability and mineralization of the coal surface. That must be taken into account in choosing the parameters of the suspension and the methods of bed deactivation.