Isotropic pitch-derived carbon fiber from waste coal

Abstract

Traditionally, waste coal impoundments have been viewed as environmental liabilities. However, the results presented herein take advantage of the aromatic chemistry of the coal component and offer an attractive path towards the utilization of waste coal in value-added products. The solid material stored in waste coal impoundments is largely comprised of fine coal particles and mineral matter. This work focuses on separating and recovering the waste coal fraction from the other materials. Once isolated, the waste coal was subjected to direct coal liquefaction (DCL) to produce a coal extract liquid, which was subsequently filtered. The filtered coal extract was then vacuum distilled forming an isotropic pitch bottom product, which was then recovered and melt spun to produce green fibers. Thermal oxidation and carbonization produced isotropic carbon fibers from waste coal, which showed mechanical properties in-line with other general purpose carbon fibers.