N.m.r. imaging studies of coal samples using solvent permeation

Abstract

The diffusion and permeation of liquids into coal has important ramifications for a wide variety of industrial processes including coal liquefaction, combustion, coal transport in water slurries, and sulfur extraction. Each of these processes depends upon the maximum internal surface area of the coal coming into contact with the permeating liquid. In contrast to other techniques using indirect methods to follow permeation, nuclear magnetic resonance imaging can be used in a completely non-invasive and non-destructive way directly to visualize and measure the changes in internal structure as coal is swollen with organic and inorganic solvents. Two-dimensional and three-dimensional imaging techniques have been used to follow the ingress of a variety of solvents into samples of coal. The images obtained show that considerable inhomogeneities exist within the coal sample with regard to the rate of solvent penetration.