Effects of increasing rejection temperatures on electricity demand for ventilation and cooling in automated metalliferous underground mines
Date
2014
Authors
Mochubele, Ekgatlamang Mothusi
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Abstract
The South African power crisis and corresponding rising costs experienced
since 2008, created a paradigm shift in terms of electricity use. The mining
sector is the second highest consumer of electricity with metalliferous mines
being accountable for 80% of the total power. Recent studies revealed that
underground ventilation and cooling accounts for 30% to 40% of total electricity
costs in an underground metalliferous mine. Hence the need to look at ways to
reduce electricity consumption in ventilation and cooling.
Work has been done on optimising efficiencies of ventilation and refrigeration
systems of underground mines. Currently, the high energy consumption is
driven by efforts to achieve a thermally acceptable environment for workers
(manned) in deep metalliferous mines which is currently between 27ºC (wb) and
29ºC (wb). However, no detailed study has been done looking at increasing
thermally acceptable environments for deep level metalliferous mine.
In this study the impact of increasing rejection temperature to 40ºC (db) was
assessed in the automated (unmanned) scenario at a maximum depth of 2811
metres. Then the power demand was compared with the manned scenario.
The results proved that automation in an underground mine has the potential of
reducing electricity cost of ventilation and cooling by more than 50%. For
example, the production rate of about 200 kilo-tons per month yield an annual
cost saving of R71 million on electricity. These cost savings can be used to
justify automation systems. Automation removes workers from the hazardous
environment and replaces them with equipment which can withstand harsher
conditions.
The introduction of an automation system in underground mines would not
come risk-free. Currently, automation systems have not yet reached a level of
removing workers completely from underground.There are instances that would
require workers to enter production zones. A Bow-Tie risk analysis was used to
show the hazards that workers would be exposed to and prevention controls
and responses to mitigate the impact the risks.
Description
A research report submitted to the Faculty of Engineering and the Build Environment, University of the Witwatersrand, in partial fulfillment of the requirements for the degree of Master of Science in Engineering
Johannesburg, 2014
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Citation
Mochubele, Ekgatlamang Mothusi (2014) Effects of increasing rejection temperatures on electricity demand for ventilation and cooling in automated metalliferous underground mines, University of the Witwatersrand, Johannesburg, <http://hdl.handle.net/10539/23253>