SOLVENT SWELLING OF MACERAL CONCENTRATES

The volumetric swelling ratios of three coals and their maceral concen trates in the presence of pyridine were determined by the displacement of a piston and by the measurement of swollen and unswollen particle size distributions using a laser diffraction particle size instrument. The use of particle size distributions allows the measurement of swel ling ratios without the possible problems of changes in particle packi ng associated with the piston apparatus. The piston apparatus, however , has the advantage that the kinetics of solvent uptake can be evaluat ed. Equilibrium swelling ratios were generally found to increase in th e order vitrinite > liptinite > inertinite, which implies that the app arent cross-link density increases in the order inertinite > liptinite > vitrinite. Extracted coals and maceral concentrates were found to h ave greater swelling ratios than raw coal samples.