CAPILLARY-LIKE CONDENSATION OF SORBED GASES IN COALS

The influence of force fields acting in the pores of coal on condensation of matter sorbed from the gaseous phase and the resulting changes in pore structure were studied. It was found that capillary-like condensation, i.e. type-2 capillary phenomena, can occur in the fine structure of the pore volume. The sorbate, when condensed as described, forms numerous spatially distributed inclusions similar to very thin films or to liquid interlayers. The bursting pressure acting therein weakens the pore structure and reduces the strength of the coal. The evidence for such phenomena is provided by data on changes in deformational, strength, electrophysical, optical, and carrier properties, resulting from the interaction of the coal with carbon dioxide, methane or their mixtures.