Conclusions and Recommendations - Coal Waste Impoundments: Risks, Responses, and Alternatives - page 154

Fluidized-bed combustion and gasification show promise for recovering
the heat content of fine coal waste while avoiding some of the operational
problems that limit use of coal fines in conventional pulverized coal-fired
boilers. The combustion of fine coal waste in advanced combustion
technologies, such as fluidized-bed combustion and gasification, is an
alternative that also shows considerable long-term promise. Further research is
needed on the use of fine coal waste slurries as feeds; incentives may be needed
if these technologies are to be utilized widely for fine coal waste combustion.
While coal combustion wastes from power plants are already being used for a
number of purposes, the issue of the safe handling of coal combustion waste
from these advanced combustion technologies should be studied further.
Both surface and underground methods are available for the disposal of
coal slurry other than in impoundments. Alternative surface methods include
incised ponds, slurry cells, combined refuse piles, and co-disposal of fine and
coarse refuse. In many instances, these methods are influenced by topography,
geology, and mining and coal preparation characteristics and are therefore site
specific. The two primary methods for injecting fine coal refuse into
underground mines are controlled flushing, where the underground workings
are accessible, and blind or uncontrolled flushing, where the underground
workings are abandoned or have caved in. A number of issues related to
underground injection of slurry—such as adequate supply of water, surface
ownership, permits, surface layout, and surface drainage—are independent of
the method of slurry injection.
Although there are alternatives to disposing of coal waste in
impoundments, no specific alternative can be recommended in all cases.
Furthermore, the alternatives that have been identified are in varying stages of
technological development and implementation. A factor limiting
implementation to this point is the cost associated with the various alternatives.
Additional research is needed to develop these alternatives further and to
evaluate the economics of these processes. The committee recommends that a
screening study be conducted that (1) establishes ranges of costs applicable
to alternative disposal options, (2) identifies best candidates for
demonstration of alternative technologies for coal waste impoundments,
and (3) identifies specific technologies for which research is warranted.
Input from MSHA and OSM regarding regulatory issues will be valuable to
such a study. The committee recommends that the use of economic
incentives be explored as a way of encouraging the development and
implementation of alternatives to slurry impoundments. The development
of incentives should be based on the full range of the portfolio of technologies
as well as the economics of the technologies. The incentives