Abstract:
Water is a very important component in the production process at
underground coal mines. Current unfavourable economic conditions have
forced the coal mining industry to identify and address every possible
bottleneck preventing optimal production. An increase in water-related
downtime was identified as one of the bottlenecks at Goedehoop Colliery’s
Vlaklaagte Shaft. The purpose of this project was to identify the various
causes that contributed to the high downtime (501 hours in 2013, which led
to a potential profit loss of R12.9 million) and to suggest possible solutions.
After a thorough investigation the main causes of water-related
downtime were identified as low water pressure and low water flow caused
by pipe leakages and bursts. The main root cause for the low water flow
and pressure was identified as being the low pressure resistance (1600
kPa) of the thin-walled galvanized steel pipes used in the underground
inbye water reticulation system. The pipes were selected according to the
previous 1000 kPa pressure requirement for the continuous miner.
However, the pressure requirement changed to 1500 kPa, which resulted in
the pipes being exposed to much higher pressures than designed for.
The water reticulation system was reviewed and current and future
underground pipe layout and water requirements were determined for the
shaft. The time frame in which the water consumption would be the
highest was determined to be between 1 January 2014 and 7 September
2014. Machine and sprayer specifications were used to determine the
water consumption at the shaft.
Three different solutions were considered to solve the water-related
downtime problem and to ensure the efficient supply of water to the newly
open sections. Permanent underground concrete dams, semi-mobile dams,
or new pipe columns with a higher pressure resistance of 3200 kPa were considered. A trade-off study (taking into consideration cost, time to
completion and ease of implementation, maintenance requirements, safety,
and flexibility) was completed to determine which of these solutions would
be most viable.
