Fly Ash Paste Utilization for Placement as Mine and Landfill Backfill at Great River Energy's Coal Creek Station

摘要

Many coal combustion products (CCPs) have historically been unsuitable for placement as mine backfill because of their physical and geochemical properties and/or regulatory status. However, innovations in paste production and transport of CCPs utilizing the high, fine particle contents of these fine-grained waste materials and their water retention colloidal properties produce a non-segregating, self-cementing material that may be environmentally suitable for placement as mine backfill. Both industry and the regulatory agencies are enthused by the possible cost reductions, both in design and construction of disposal sites, and the reduced environmental impacts of CCP realized by implementation of this new use/disposal technology. Great River Energy (GRE) in association with Golder Associates Inc. (Golder) recently undertook the task of evaluating the feasibility of utilizing engineered fly ash paste as backfill in mine reclamation and for disposal in Inert Waste landfills, with the goal of reducing CCP disposal costs at GRE's Coal Creek Station generation facility. Utilization of paste technology was proposed and a testing and evaluation program was begun in close consultation with various regulatory agencies. Based on the results of the evaluation, Great River Energy submitted a comprehensive report with its request to have fly ash paste reclassified as an inert waste. The program began with complete laboratory analysis of the material, followed by a field-scale demonstration of the technology. Figure 1 provides an example of Fly Ash Paste Placement. All of this was done with the involvement of the state regulatory agencies responsible for overseeing Utility operations. This paper presents a summary of an application of fly ash paste technology that is environmentally sound, reduces disposal costs, and improves mine reclamation efficlencies.