PETROGRAPHIC AND CHEMICAL-PROPERTIES OF CARBONIFEROUS RESINITE FROM THE HERRIN-NO.-6 COAL SEAM

Resinite is a naturally occurring substance found in coal and derived from original plant resins. It is ubiquitous in Noah American coals an d comprises 1 to 4% by volume of most Illinois coals. It has been comm ercially exploited in the western USA for use in adhesives, varnishes and thermal-setting inks. The major objectives of this study were: (1) to separate resinite macerals from the Herrin No. 6 coal seam and to carefully verify, by petrographic and fluorescence microspectrophotome tric methods, that the separated material was indeed resinite; (2) to characterize the chemical composition of the separated resinite by Py- GC-MS techniques; and (3) to confirm the earlier results that show tha t this Carboniferous resinite was a much different chemical substance than the Cretaceous and younger resinites. An additional objective was to compare the separated resinite to the resinite being commercially exploited in the western USA. High purity fractions of resinite concen trates were separated from the Herrin No. 6 coal by a combination of d ensity gradient separation and sink-float techniques. The chemical str ucture of the resinite concentrate indicated by the Py-GC-MS analysis is that of a straight chain aliphatic polymer much like common polyeth ylene. This result confirms the earlier work of Nip et al. [Nip, M. de Leeuw, J.W., Crelling, J.C., 1992. Chemical structure of bituminous c oal and its constituent maceral fractions as revealed by flash pyrolys is, Energy Fuels 6, 125-136.]. The assumption that the resinites in th e Illinois basin were similar in nature to the commercial resinites of the younger coals of the western USA appears invalid in the case of t he resinite in the Herrin No. 6 coal. Although the botanical function of the Carboniferous resinite is at present unclean it is clear that t he cutinite and resinite precursors had not yet evolved to the point w here they had differentiated into significantly different chemical com pounds. (C) 1998 Elsevier Science B.V. All rights reserved.