ESTIMATION OF COAL HYDROPHILICITY BY FLOW MICROCALORIMETRY

The adsorption heat of methanol on a coal surface was measured by flow microcalorimetry (FMC). Eight coals, each with different oxygen conte nts, were used as adsorbents. Methanol adsorption heat depends on the number of hydrophilic groups on the coal surface, while the amount of methanol adsorbed is independent of the surface chemical composition o f coal. We examined a range of methanol concentrations in n-hexane: 2- 20 g/l, and found that the adsorption heat reaches equilibrium before 20 g/l methanol concentration. The heat of methanol adsorption at 20 g /l is effected neither by the particle size distribution nor by the qu antity of inorganic impurities in the coal adsorbent; however, methano l adsorption heat varies in direct proportion to the coal hydrophilici ty, a parameter affecting the recovery of fine coal in oil agglomerati on and flotation. FMC data for methanol adsorption heat can be used to estimate the coal hydrophilicity. Estimates obtained in this way agre e well with those obtained by Sun's surface-component theory. (C) 1998 Elsevier Science B.V.