Coal Age

JUN 2013

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coarse coal continued where p is the composite density of particles passing through the separator. Typically, this density value would correspond to specific gravity values of 1.5 to 1.9 SG for ash levels observed in typical eastern feed coals. A plot of the theoretical sorter capacity as a function of particle diameter for different feed densities is provided in Figure 10. The plot was generated using a nominal belt velocity of 10 ft/sec. According to the plot, the theoretical maximum capacity for the larger 2-inch particles would fall in the range of 60 to 120 tph per foot of scanner belt width, depending on the specific density of the feed solids. The theoretical capacity would fall sharply to 7-14 tph per foot of belt width for particles smaller than ¼ inch in diameter. These finer particles can be easily missed when intermixed with coarser particles that are being separated at much higher production rates. Conclusions Several series of experimental test runs were conducted to evaluate the potential of an electronic coal sorter for upgrading of run-of-mine coal from an eastern U.S. mining operation. The test data indicate that this novel sorting technology can effectively remove unwanted mineral matter impurities contained in coarse (2 x ¼ inch) coal feeds. Due to inherently low capital and operating costs, this unique technology has the potential to serve as a viable coal cleaning alternative for sites that are water constrained or that have too low tonnage to justify a fullscale coal preparation facility (e.g., highwall miner applications, small contract mines with long truck haulage routes, etc.). More importantly, as a dry process, this method of separation avoids issues related to water usage and waste disposal that typically occur using traditional water-based separation processes. The compact footprint of this process may also allow the technology to be integrated into mining production units in underground mines, thereby reducing the demand for transporting and disposing wastes in dedicated surface refuse areas. The process is moving rapidly into the commercial sector as evidenced by a recent production-scale installation of this new technology (see Figure 11). Kiser and Luttrell are from the Mining & Minerals Engineering Department at Virginia Tech. Roos is with Mineral Separation Technologies. They presented this paper at Coal Prep 2013. Acknowledgment The authors would like to acknowledge the Appalachian Research Initiative for Environmental Science and the industrial participants for supporting this work. References Akers, D. J., 1996. "Coal Cleaning Controls HAP Emissions," Power Engineering, June. Figure 10: Theoretical maximum sorter capacity for mono-sized particles of different densities. Couch, G.R., 1995. Power From Coal—Where To Remove Impurities?, IEA Coal Research, London IEACR/82, 87 pp.. Couch, G.R., 2000. "Opportunities for Coal Preparation to Lower Emissions," International Energy Agency (IEA), CCCr30, London, 46 pp. Gardner, JS, Houston, KE and Campoli, A (2003) Alternatives analysis for coal slurry impoundments. SME Annual Meeting, Feb. 24.–26, Cincinnati, OH, Preprint 03-032, 1-5. Luttrell, G.H., 2008. "Coal Preparation," Chapter 4, in Meeting Projected Coal Production Demands in the USA: Upstream Issues, Challenges, and Strategies, M. Karmis (Chair), National Commission on Energy Policy, Published by Virginia Center for Coal and Energy Research (VCCER) of Virginia Tech, December, 2008, pp. 106-143. Meenen, G., 2005. "Implications of New Dewatering Technologies for the Coal Industry,"Invited Lecture, Center for Advanced Separation Technologies (CAST) Workshop, July 26-28, 2005, Virginia Tech, Blacksburg, Virginia, 14 pp. Figure 11: Photograph of a recent production-scale installation of the DriJet sorter technology. June 2013 Orr, F.M. (Committee Chair), 2002. "Coal Waste Impoundments: Risks, Responses and Alternatives," Committee on Coal Waste Impoundments, National Research Council, National Academy Press, Washington, D.C., 230 pp. 51

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