Adhesion of a coal grain to a coal grain in an alcohol

Abstract

Measurements of the destruction time of the coal sediment column structure formed from the following fractions of coal grains: (1) +100-200 μm, (2) +200-300 μm, (3) +300-400 μm, and (4) +400-500 μm have been carried out. Using the relationship between the reciprocal of the destruction time and the average diameter of the size fractions of coal grains, the critical diameter of the grains was determined. Next, using the critical diameter and surface free energy components and parameters of the coal and alcohols, the correlation between the stability of the coal-alcohol-coal system and the work of adhesion of coal to coal and alcohol to coal, and the viscosity, density, and surface tension of alcohols were investigated. From the measurements and the calculations it was found that the destruction time depended on the size of the coal fractions and the nature of the alcohol, but the critical diameter of the coal grains did not depend on these parameters. It was also found that the detachment a coal grain from another coal grain in an alcohol occurred by disruption of the alcohol film present between the two coal grains and that the increase in the attachment forces between the two coal grains as a function of the molecular length of alcohols was caused by an increase in the perimeter of the contact plane.