fluidized bed boilers are operating on waste coal for electricity or process steam generation.
Improved coal processing also offers potential for responding to future environmental requirements. For example, the development of new or modified flotation processes permit fuel oil to be replaced as a froth flotation collector if it is prohibited because of disposal concerns.
There are two technical areas where the development of improved coal processing technologies offers the greatest potential to increase resource recovery (Peterson et al., 2001; NRC, 2002b; CAST, 2003):
The use of improved information technology, perhaps in conjunction with improved online analysis capabilities, to optimize the performance and efficiency of existing unit operations; and
The development and deployment of better materials with which to construct vessels, separation devices, and conduits.
The primary needs for research in the broad environmental area are to support the regulation of existing and future mining operations and to mitigate the effects of past mining practices.
Existing Mine Operations. There is still an incomplete understanding of how strata behave after coal is extracted from both surface and underground mines, and the hydrologic consequences of mining are not fully understood. For surface mining, the properties of the altered subsurface—particularly the leaching and permeability characteristics—are likely to be different compared to those existing prior to mining. For underground mining, the collapse of strata above a coal seam into the mined void can propagate all the way to the surface, damaging buildings and disrupting the quantity and quality of surface and subsurface water flows.
Disposal of mine waste can be a significant problem, particularly where the coal has to be cleaned before shipment (e.g., see NRC, 1975; 1981; 2002a; 2006). There is a need for enhanced understanding of the physical and chemical behavior of spoil stored in valleys or waste—from coal combustion or coal preparation plants—that is disposed in surface or underground mines. Waste management is a major problem where land either is not available or is more valuable for other productive uses. Increased research to develop productive uses of mine waste offers considerable potential to reduce waste disposal issues.
Mine Decommissioning and Closure. Federal regulations for decommissioning and closure of mining operations are administered by the Mine Safety and Health Administration (MSHA), the Office of Surface Mining Reclamation and Enforcement (OSM), and the EPA—in some cases state and local governments