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Out-of-seam dilution: Economic impacts and control strategies 175

9.4.2.6 Pick force CID

This CID method measures changes in the force exerted on one or more of the picks on
a continuous miner cutterhead. The energy required to break differing types of rock
results in varying forces being applied to any given pick. This phenomenon can be
used to determine when the mining machine cuts into a different type of strata. This
type of system can be conveniently integrated into the mining machine keeping com-
ponents compact and protected. It is also capable of instantaneous feedback. To date, a
commercial unit of this type has not been developed for advanced testing [19].

9.4.2.7 Application of CID technology in the Illinois Basin
One of the newest underground coal mines in the Illinois Basin supplies fuel to an
electric-power-generating plant that is located on the same property and was designed
to burn ROM coal. Control OSD is critical to the operating and economic success of
this operation. To achieve target levels of OSD, mine engineers in collaboration with
equipment manufacturers have tested CID technology combined with artificial intel-
ligence (AI) to the control continuous miner’s cutterhead height. CID sensors capture
data on coal-roof interface profiles, which are remembered by AI systems and used to
constrain machine control functions within established tolerances. A commercial CID
sensor is mounted on the mining machine together with a set of inclinometers that
identify the cutterhead position at any given point in time. Graphic displays of the
cutterhead position and coal-rock interfaces in the roof and floor enable the machine
operator to selectively mine coal while minimizing dilution.

9.5 Conclusions and recommendations

This chapter presents novel data describing OSD impacts on both clean coal quality
and on costs attributable to OSD including the cost of quality impacts, which are sum-
marized in the following conclusions:
1. OSD has a significant impact on clean coal product quality. This impact can be variable from
mine to mine, but on average, results will not differ much from those obtained in the study
described earlier. That study found that for five Illinois Basin mines, OSD’s average impact
on clean coal product quality was an 8% increase in ash content and a 2% increase in sulfur
content over inherent content of these variables in the coal seam.
2. Analysis of channel samples revealed that roof and floor strata contained significantly con-
centrated levels of mercury and most trace elements of note to the coal industry. Mercury
was used as a surrogate for all trace elements, and the study determined that OSD’s average
impact on clean coal product quality was a 4% increase in mercury content. Increases in
several other trace element concentrations were also measured, some of which were star-
tling, for example, cadmium (Cd) and chromium (Cr) registering 850% and 150% increase,
respectively.