97/04375 Radiation properties of pulverized coal and ash particles: Liu, L. et al. Ranshao Kexue Yu Jishu., 1996, 2, (2), 127–133. (In Chinese)

Abstract

Geochemical and coal petrographical analyses were undertaken on low-rank Upper Pliocene Balingian coal from Sarawak, Malaysia, in an attempt to reconstruct the conditions during peat accumulation and the subsequent coalification processes. Chemically, the coal in this study is characterised by high moisture, low ash yield and low sulphur content. The low ash yield and low sulphur content, together with the lack of epiclastic partings clearly indicate that it was deposited in ombrotrophic raised bogs. The coal was plotted in the Type III terrigenous kerogen zone of the van Krevelen diagram, with H/C value below 0.9. This shows that the coal was derived from plant materials of terrigenous origin and is still immature for petroleum generation. The petrographical study reveals, nonetheless, the expulsion of early generated hydrocarbons from the disintegration of suberinite, and also from phlobaphinite and cutinite. Petrographically, the coal is dominated by huminite, with low to moderate amounts of liptinite and low amounts of inertinite, pointing to predominantly anaerobic deposition conditions in the paleomires, with limited thermal and oxidative tissue destruction. Most of the studied samples are characterised by low TPI and high GI values, and are plotted on the marsh field of the Diessel's diagram, or it could also originate from decomposed wood in forested swamps. Nevertheless, coals originating from both these sources usually generate high ash yield, which is not the case for the studied coal. This shows that the interpretation as suggested by the Diessel's diagram is not valid for the studied coal. The coal has a mean random huminite reflectance between 0.26 and 0.35%, suggesting a lignite coal rank for the coal. Nevertheless, geochemical classification based on total moisture and calorific value suggests a subbituminous C rank.