Geology Reference
In-Depth Information
for burning fine coal waste. Gasification technologies are also promising for
coal water slurries, because they operate more efficiently, and emerging
technologies can utilize the water from the slurry as a steam source needed for
the gasifier. DOE is already promoting advanced combustion technologies
through research and demonstration projects. Further research is needed on the
use of fine coal waste slurries as feeds, and 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 management of coal combustion waste from these
advanced combustion technologies should be studied further.
ALTERNATIVES TO DISPOSAL IN IMPOUNDMENTS
While impoundments are widely used in the Eastern U.S. coalfields for the
disposal of slurry from the preparation plant, there are several alternative
methods of slurry disposal. Some of these methods are already in practice
wherever applicable. These methods are discussed here as surface and
underground methods.
Surface Methods
Throughout the United States and in other countries a number of
alternative surface disposal methods have been used that do not rely on a typical
cross-valley impoundment structure. Some methods are designed for slurry
only, others for dewatered fine refuse, and still others for a combination of fine
and coarse refuse ( Table 7.2 ). These methods are influenced by topography,
geology, and mining and coal preparation characteristics and are therefore not
universally applicable.
Incised ponds function as normal slurry impoundments and are considered
to be a form of impoundment. Unlike other impoundments, incised ponds do
not rely on a structure (i.e., an embankment) to contain the slurry. Incised ponds
can accept any form of coal waste but are commonly used to contain slurry.
This method of surface disposal is most common in regions where surface
mining is practiced. In the United States, their use is limited primarily to the
Interior Coal Basin (specifically, Illinois, Indiana, Ohio, Pennsylvania, and
western Kentucky). Surface mining produces long end-cuts and inclines, which
are usually allowed to fill with water to form a permanent lake. These lakes are
at or below the level of surface drainage and
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