Page 77 - Advances In Productive, Safe, and Responsible Coal Mining

Optimization of coal recovery 5

and production rate as a
function of panel dimensions

‡,§ ¶
†
Kwame Awuah-Offei*, Angelina Anani , Joseph C. Hirschi , Emmanuel Ewusie
†
*Missouri University of Science and Technology, Rolla, MO, United States, Pontifical
‡
Catholic University of Chile, Santiago, Chile, Smart Solutions, Komatsu Mining
§
Corporation, Mt. Vernon, IL, United States, Mining and Mineral Resources Engineering,
¶
Southern Illinois University, Carbondale, IL, United States, Chevron Corporation, Houston,
TX, United States

5.1 Introduction

It is estimated that at least 60% of coal production from underground mining comes
from room-and-pillar (R&P) mines [1]. Despite many advantages that make it popu-
lar, one of the disadvantages of R&P mining is the low recovery that results from leav-
ing pillars to support overlying material. Typical coal recovery in R&P mines ranges
from 30% to 60%, with higher recovery possible only with pillar extraction. Geotech-
nical properties of coal and overlying material determine the size of pillars required to
support the mine and, therefore, coal recovery. Design parameters such as panel width
also affect recovery as they dictate how many barrier pillars will be required and their
dimensions. Additionally, panel dimensions affect the production rate possible during
mine operations.
Production panels are separated from each other by barrier pillars, which are
designed to reduce the likelihood of progressive failures from adjacent workings.
The width of barrier pillars separating two panels depends on the size of the panels
and the integrity of pillars within the panels. However, barrier pillars, like pillars
within a panel, reduce coal recovery. It is desirable then to reduce the amount of coal
left in place in barrier pillars, if it is possible to do so without reducing safety. For
panels containing the same size rooms and pillars, larger (wider) panels are likely
to result in higher coal recovery because they result in fewer barrier pillars.
For most R&P mines, panel width is specified by the number of entries that are
mined. The number of entries affects the production rate during mining operations
in the panel. For example, mines with smaller panel widths (fewer entries) require
fewer haulage units to minimize congestion and to ensure adequate ventilation. This
can result in lower overall production rates despite faster advance rates associated
with smaller panel widths. On the contrary, mines with larger panel widths (more
entries) can use more haulage units because congestion and ventilation concerns
are not as constraining. Also, more haulage units may be required to maintain produc-
tion rates since haulage travel distances are longer. Otherwise, the utilization of the
Advances in Productive, Safe, and Responsible Coal Mining. https://doi.org/10.1016/B978-0-08-101288-8.00013-4
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