ies that would reduce underground
coal production cost by 20%. This report documents studies in three areas: 1) industrial
engineering studies of a high-voltage miner and face haulage systems, 2) improved
efficiency of continuous miner wet scrubbers through design modifications and surfactant
use, and 3) control of out-of-seam dilution. The Coal Industry Research Steering
Committee identified these areas as high priority to achieve the desired cost reduction.

Industrial engineering studies involved 1) performing time studies and production
modeling of typical mining layouts and equipment currently in use in Illinois, and 2)
assessing impact of a battery shuttle car and a surge car on production. Studies indicate
that use of battery shuttle cars has the potential to increase a typical section production by
about 15%. Performance characteristics of currently used face haulage systems were
developed to identify needs for advanced face haulage systems.

Improving efficiency of wet scrubbers for dust control involved systematically evaluating
the effect of variables such as spray nozzle type, spray pressure, volume of water,
surfactant concentration, and spatial distribution of sprays. Two-filter, two-spray
concepts for a wet scrubber were tested. Laboratory results indicate that a properly
designed two-filter, two-spray scrubber can reduce dust concentrations by over 50% from
3.58 mg/m
3
to 1.9 mg/m
3
. These results were achieved with a smaller volume of water (5-
gpm) at lower spray pressure (40-psi) with only 50% of the surfactant concentration used
in previous tests.

This study attempted to analyze dilution of run-of-mine coal and its impacts on cost due
to intentional or non-intentional mining of roof and floor strata. A simplified
mathematical model to understand dilution was developed. An analysis of questionnaire
data and personal interviews with mining professionals led to the conclusion that an
education and training program, emphasizing cost impacts of dilution, should be
developed for production workers.

EXECUTIVE SUMMARY

Background

With financial support from the Illinois Clean Coal Institute and coal mine operators
throughout Illinois, the authors have been working on the project Identification of Cost
Cutting Strategies for Underground Coal Mines in Illinois, since October 2000. A 20%
cost cutting goal, with respect to the current typical FOB price of $20 per ton, was
established. The project is being driven by a steering committee, hereby known as the
Coal Industry Research Steering Committee, consisting of representatives from most of
the active coal companies in Illinois as well as other industry partners. The first phase of
the project was completed under a previous ICCI grant. The following four top-priority
areas of focus were identified for future research and development efforts.

1. Potential of high-voltage continuous miners to increase face productivity
2. Development of alternative face haulage systems to optimize production capacity
of continuous miners
3. Improved dust control in face areas
4. Control of out-of-seam dilution

This report documents results of studies performed in these areas.

Area I: Industrial Engineering Studies of High-Voltage Continuous Miner
Performance and Alternate Face Haulage Systems

Industrial engineering studies tasks included: 1) production modeling of high voltage and
standard voltage continuous miners in a room-and-pillar layout, 2) collection of time
studies data in a longwall development section and its production modeling, 3) perform
time studies on face haulage systems currently in use to develop their characteristics, and
4) offer an information transfer workshop to mining professionals in Illinois.

Two time study data collection forms were developed in concert with industry and used
throughout the project. Time study data collection involved two persons; one at the
production face and one at the feeder. Statistical data analysis procedures were utilized to
develop elemental times data, which were then used in the Suboleski-SIU Production
model (SSP) for production estimation.

The SSP is a simplified production model for partial extraction mining layouts. It
estimates expected unit shift production rates by calculating the mining rate averaged
over two or three crosscuts of advance (belt move to belt move). The original model,
developed by Suboleski, has been modified at SIU to improve data input and data output
characteristics.

The results of the industrial engineering studies are summarized below:


The major difference between standard-voltage and high-voltage miners is in load
time during normal cutting operation. In a side-by-side comparison of two
continuous miners at one mine, average load time, change-out time, and reset time
during normal operation for a standard-voltage miner were 0.772, 0.622, and
1.175 minutes, respectively. Similar data for a high-voltage miner were 0.555,
0.628, and 0.917 minutes, respectively. Similar data for the two miners during
clean-up operation (1.461, 0.596, 1.792 and 1.408, 0.595, 1.754 minutes,
respectively) are statistically similar. Therefore, a high-voltage miner has the
potential to increase production by 30% provided coal can be hauled away from
the face, and the roof bolting cycle is matched with the cutting cycle.

Haulage unit capacity is the most important variable affecting production
potential of a mining section followed by loading rate of the continuous miner.
Haulage unit capacity must be suitably designed for continuous miner
characteristics for optimal production.

Continuous haulage may have limited potential in Illinois mines because of
rolling floor structure, and relatively weak roof and floor conditions. Therefore,
battery shuttle cars alone or in conjunction with a surge car may be the best
alternative to increase production potential of standard- or high-voltage
continuous miners.

Tethered shuttle cars limit production potential of a continuous miner since no
more than three such shuttle cars can operate effectively.

Area II: Development of a Modified Wet Scrubber for Improved Dust Control

Improved productivity in the face area requires that respirable dust in the mining areas be
controlled to less than 2 mg/m
3
. Since wet scrubbers on continuous miners represent the
most common technology for dust control, an improved wet scrubber with the use of
surfactants was an important research area in this project. The more specific objectives of
this research were to 1) systematically evaluate the effect of different variables affecting
dust control, and 2) develop and test concepts for an improved wet scrubber.

An industry driven dust control steering committee met three (3) times to provide
oversight and guidance to this research. All studies were performed in the SIUJoy Dust
Control Facility located at the Illinois Coal Development Park in Carterville, IL. The
variables considered here were number of filter layers, type of spray (full-cone or hollow-
cone, vertical or horizontal), spray water volume, surfactant concentration, and number of
sprays and number of filters. Statistical experiment design and data analysis techniques
were utilized. The following is a summary of the results.


Reducing spray pressure from 80-psi to 30-psi for a single filter, single horizontal
spray has negligible effect on dust concentration. Therefore, lower water spray
pressure may be used.

Concepts for a two-filter, two-spray wet scrubber were developed and
incorporated into the scrubber unit provided by Joy. In this design, the first water-
only vertical spray (2-gpm) wets most of the coarse dust. The ultra-fine dust, non-
wettable by water alone, is wetted by the second vertical water-surfactant spray
and removed by the second vertical or inclined filter.

An optimized two-filter, two-spray wet scrubber reduced dust concentrations by
over 50% from 3.58 mg/m
3
to about 1.9 mg/m
3
in the laboratory. This was
achieved with a smaller volume of water (5-gpm) at 40-psi spray pressure with
about 50% of the surfactant concentration used in previous tests.

A dust measurement laboratory was developed at SIU in cooperation with the
Mine Safety and Health Administration (MSHA).

The dust control steering committee recommended that the developed concepts be
incorporated into a commercial scrubber and tested in the field.

Area III: Identification of Best Practices for Reduction in Out-of-Seam Dilution

In Illinois, only 60%-70% of the run-of-mine coal is of marketable quality for power
generation. The remaining 30%-40% has very low heating value ( 1,000 Btu/lb)
because of high ash content related to immediate roof and floor strata associated with a
coal seam. The mining of the immediate roof and floor strata, along with rock bands in
the coal seam, represent in-seam and out-of-seam dilution (OSD).

Since only OSD may be controlled, most of the discussion here refers to OSD only. The
OSD affects production cost and profitability of a mining enterprise since the marketable
coal represents the only revenue stream. The OSD facet of mining and its impacts on
production costs is not well understood. It is only in the last 2-3 years that industry has
considered ways to reduce OSD. The goals of this research were to 1) understand the
impact of OSD on