Abstract
Four Pennsylvania anthracites of varied carbon content and mineral matter levels were selected from active mines and heat-treated to increasing temperatures. Carbides formed at ~2200�C and then decomposed at ~2500�C. This carbide formation and decomposition process aided in the global graphitization mechanism of the anthracites, and was the sole graphitization mechanism for at least one of the anthracite samples. The most highly graphitizing anthracite was demineralized and then heat treated to typical graphitization temperatures. X-ray diffraction (XRD) of the heat treated de-mineralized sample showed that the (112) peak, which is indicate of three dimensional ordering, previously observed in the native heat-treated anthracite were no longer present. The demineralized anthracite was re-mineralized by adding four types of minerals back to the demineralized sample. The re-mineralized sample was then heat treated and was then found to exhibit the (112) in XRD. The absence of the (112) XRD peak after removal of minerals and heat-
treatment, followed by re-appearance of the peaks after re-mineralization and heat treatment strongly suggests that the anthracite was only graphitizable if mineral matter was present. Mineral matter associated with anthracite must have some beneficiary role in the global graphitization mechanism, and may explain why some anthracites are more graphitizable than others.