Alternatives for Future Coal Waste Disposal - Coal Waste Impoundments: Risks, Responses, and Alternatives - page 116

burning of low value coals, i.e. coals with a large amount of noncombustible
material (ash). Another technology is the use of coal water slurry as fuel for
traditional combustors or gasifiers.
There are several alternatives to disposing of fine coal waste in
impoundments, such as disposing of it in surface fills and underground
workings. However, these options are often limited by factors such as
topography, cost, and safety.
The ramifications of all potential options may be explored to create a Type
III industrial ecology model for the coal/electric power industry ( Sidebar 7.1 ).
Figure 7.1 shows that through selective mining and other means, coal
preparation needs can be restricted to Level 3 ( Sidebar 7.2 ) and below, thus
producing only limited fine coal waste slurry. If coal is cleaned to Level 4, the
options of waste utilization and alternative disposal locations remain. Finally,
existing ponds can be reclaimed, and the fine waste can be used in a similar
manner.
SIDEBAR 7.1 INDUSTRIAL ECOLOGY
In the past, many industries operated as individual entities; however,
the individual operations can have widespread impacts. The philosophies
and approaches of industrial ecology may be used to integrate an
individual industry, such as coal mining, with natural ecosystems and
other industries. Industrial ecology is defined by Graedel and Allenby
(1995) as a rational way for humans to maintain their existence with
changing economies, cultures, and technological capabilities. Individual
systems must work with each other to optimize the total materials cycle,
including resources, energy, and capital.
In the biological world, metabolism is the key process for life, for
ecological balance, and for providing an increased capacity for living
things. When the ecological balance is disturbed, species perish or mutate
until a new balance is established. Industrial metabolism adapts the
concept to the industrial world. Related industries in the industrial system
are designed to work together to imitate or mimic the metabolic process.
This process does not exist in nature. Jelinski et al. (1992) present three
models of industrial ecosystems based on this analogy (see figure next
page). In Type I, the flow process is unidirectional from resources through
consumption to waste. With time, the system's resources will be depleted,
and its wastes will overwhelm it. In Type II, internal cycling loops are
developed, leading to limited input of resources and limited waste. This
system is also not sustainable because input flows to waste in only one
direction. In the ideal Type III system, industrial processes are similar to
the biological ecosystems model, and full cyclicity is achieved.