MINERAL DIVERSITY AND ALTERNATIVE RESOURCE POTENTIAL OF WYOMING COAL BY-PRODUCTS

Despite continued reductions in domestic coal use, the U.S. has a large economic incentive to identify and develop industries that support and utilize coal by-products. As the dominant coal producing state in the U.S., contributing approximately 42% of all U.S. coal stocks (Luppens, et al. 2015*), Wyoming coal by-products offer a long-term sustainable supply of alternative resource materials. This investigation provides a foundational analysis that is crucial for the utilization of fresh and legacy coal by-products including alternative trace metal ore stocks (including REEs), alumina-silicate materials, and potential industrial mineral synthesis (zeolites). Coal by-products were collected at six individual coal-fired power stations, both in the Powder River Basin (PRB) and Green River Basin (GRB) of Wyoming. Based on initial geochemical and element characterization of major, minor, and trace components, individual samples were evaluated by X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). PRB and GRB samples are different in geochemical composition and related mineral behaviors. PRB samples are calcium dominated, while GRB samples are silica dominated, with Fe-enrichment in some locations. Major cation and trace element abundances also vary between the two basins. This strong heterogeneity results in a variety of mineral species and several possible alternative resource uses for the two stocks. Geochemical variation coupled with the sheer volume of available material makes these potential resources particularly interesting for future utilization.

*Luppens, J.A., Scott, D.C., Haacke, J.E., Osmonson, and L.M., Pierce, P.E. (2015). Coal Geology and Assessment of Coal Resources and Reserves in the Powder River Basin, Wyoming and Montana. U.S. Geological Survey Professional Paper 1809.