The potential use of coal mine refuse as feedstock for gasification or combustion and concurrent elimination as a source of acid mine drainage

Abstract

The mining and processing of high sulfur coals produce millions of tons of waste rock yearly; mostly shales that are both organic-rich and potentially toxic. The toxicity results from the oxidization of the iron disulfide minerals when exposed to the atmosphere with the subsequent production of acid mine drainage. These rock materials are specially handled and chemically treated in an attempt to prevent the production of acid and the resultant impact upon the quality of surface- and groundwater. Many such reclamation attempts are not successful. As a result, acid mine drainage is the single most serious environmental problem facing the high-sulfur coal industry. The burial and isolation of these materials which attempt to eliminate their toxic potential at the same time, precludes the utilization of the potential energy source represented by their organic content. Many of these materials have organic contents sufficiently high to provide the heat potential of lignite. It is proposed that these waste materials be utilized as feedstock for gasification or combustion. This would allow to take advantage of their energy potential while at the same time rendering the materials environmentally inert due to the thermal decomposition and subsequent oxidation of the iron disulfide minerals. The resultant thermally altered shales could then be used in reclamation as synthetic minesoils. The data presented here evaluate the properties of these materials as conversion feedstock.