EFFECT OF MINERAL MATTER COMPOSITION ON THE GRAPHITIZATION OF ANTHRACITES

摘要

This research was carried out with the aim of evaluating the influence of the mineral matter, amount and composition, on the structural order of the graphite materials prepared from anthracites by high temperature treatment. An Spanish anthracite was separated in density fractions with different mineral matter contents and similar composition and texture of their organic matters, thus reducing the factors which influence the graphitization of the anthracites to the mineral matter. The anthracite and their fractions with ash contents ranging from 2 to 19 wt.% were heated at 2673, 2773 and 2873 K. The crystallinity and orientation of the graphitized samples were estimated by X-ray diffraction and Raman spectroscopy, respectively. The degree of structural order of the graphite materials was found to increase with the mineral matter content of the raw anthracite. The mineral matter of the anthracite preferentially promotes the lateral coalescence of the crystallites during graphitization. Reasonable good linear correlations were found between the ash content of the anthracites and the crystallite size La. Among the different constituents of the coal mineral matter, Al and Si, mainly present as aluminium silicates, act as catalysts during the graphitization of anthracites, their influence being similar to that of the bulk mineral matter. The catalytic effect of Fe seems to depend on its distribution in the anthracite.