The Bushveld Complex in South Africa is a geological formation that hosts approximately
87% of all the known world platinum group metal (PGM) resources and reserves. It produces
about 77% of the world’s primary platinum production. However, the sheer size of the
resources and reserves obscures the fact that the PGM mineral resources are a wasting
asset, and should therefore be extracted optimally in order to ensure sustainable production.
In addition, a 2006 survey of research and development (R&D) needs of the South African
platinum mining companies by the CSIR-Miningtek, noted that out of 19 possible R&D areas,
layout optimisation is one of the top four priority R&D focus areas. Section 51 of the Mineral
and Petroleum Resources Development Act (MPRDA) of 2002, of South Africa, also
emphasises that owners of mining rights should optimally extract mineral resources. About
70% of the platinum production from the Bushveld Complex is extracted using conventional
mining methods, while the remainder comes from hybrid and mechanised mining methods. It
was therefore prudent to focus on optimising conventional mining layouts.
Optimisation in mining broadly requires extracting the maximum amount of ore by excavating
and moving the minimum amount of waste in the shortest possible time and in the safest and
most environmentally acceptable manner. In open-pit mine planning, this broadly requires
minimising the waste stripping ratio, while in underground mine planning it principally
requires minimising the metres of waste development. A literature review revealed that
minimising waste development in conventional breast mining is predominantly achieved by
increasing level and raise spacing. However, when level and raise spacing are increased,
other factors such as productivity are negatively affected, thus requiring a delicate trade-off
of contradicting factors. This characterises the problem as a multi-criteria optimisation
process that should be solved using multi-criteria decision analysis (MCDA) techniques.
The Analytic Hierarchy Process (AHP) was the most appropriate MCDA methodology for
solving the problem of optimising level and raise spacing. By using real geological data on
the orebody code-named OB1 that was typical of Bushveld Complex platinum reef deposits,
the optimal range of vertical level spacing derived was 30m-50m, while the optimal range of
raise spacing was 180m-220m. The layout designs and schedules were done in Mine2-4D®
and EPS® software suite, which is one of the mine design and planning software currently
used by the South African platinum mining industry for long-term mine planning. The
research methodology used in this thesis and the results obtained were received positively
by the South African platinum mining industry because for the first time in several decades, a
holistic methodology and practically acceptable solution had been obtained for the
controversial debate of optimising level and raise spacing for conventional mining layouts.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/8291 |
| Date | 15 July 2010 |
| Creators | Musingwini, Cuthbert |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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