Impacts of out-of-seam dilution on clean coal quality

摘要

Out-of-Seam dilution (OSD) is the dilution of coal that occurs due to mining of strata above and below the coal seam. Portions of dilution cannot be prevented. However, there exist opportunities to reduce it significantly. The cost impacts of dilution are not well understood or researched currently. The contemporary view is that since dilution is rejected in coal processing, it does not have any impact on coal quality. However, the authors have conducted studies on thirteen units of five Illinois coal mines and found that OSD profoundly impacts clean coal quality by increasing ash, sulfur, mercury and other trace-elements in the clean coal product. The cost impact of this quality deterioration has been estimated to be approximately 5.63 dollars /ton of mined roof and 1.39 dollars /ton of mined floor material. When the costs incurred in mining, processing and disposal are added, it has been estimated that costs related to OSD are 4.08 dollars/clean ton for an average Illinois coal mine. Even if 50 percent of the OSD can be controlled, cost savings greater than 2.00 dollars/clean ton can be realized which will provide greater competitive advantage to coal as a fuel of choice.