Utilization of lightweight materials made from coal gasification slags. Quarterly report, September--November 1994

Coal gasification technologies are finding increasing commercial applications for power generation or production of chemical feedstocks. The integrated-gasification-combined-cycle coal conversion process has been demonstrated to be a clean, efficient, and environmentally acceptable method of generating power. However, the gasfication process produces relatively large quantities of a solid waste termed slag. Regulatory trends with respect to solid waste disposal, landfill development costs, and public concern make utilization of slag a high-priority issue. Therefore, it is imperative that slag utilization methods be developed, tested, and commercialized in order to offset disposal costs. In previous projects, Praxis investigated the utilization of ``as-generated`` slags for a wide variety of applications in road construction, cement and concrete production, agricultural applications, and landfill. We determined that it would be extremely difficult for ``as-generated`` slag to find acceptance in the marketplace even at no cost because the materials it could replace were abundantly available at very low cost. It became apparent that a more promising approach would be to develop a variety of value-added products from slag that would meet specific industry requirements. This approach was made feasible by the discovery that slag could be made into a lightweight material by heating it to between 1600 and 1900{degree}F in a kiln, which indicated the potential for using such materials as substitutes for lightweight aggregates. Between 1987 and 1993, the technologies to produce these materials from slag were developed by Praxis with funding from the Electric Power Research Institute, Illinois Clean Coal Institute, and internal resources