Resources in South Africa
The PGM resources of the Bushveld Igneous Complex (BIC) were
discovered by Hans Merensky and Andries Lombaard in 1924. Within
the complex, three horizons, the Merensky Reef, UG2 Chromitite and
the Platreef are mined for PGMs and make the BIC the largest PGM
resource in the world. Platinum and palladium production from the
BIC represents approximately 75% and 40% of annual global
Estimated platinum & palladium resources
In 1999, Professor Grant Cawthorn, the Platinum Industry's
Professor of Igneous Petrology at the University of Witwatersrand,
South Africa, published a new estimate of the platinum and
palladium resources of the BIC.
For his calculations, Cawthorn assumed a maximum mineable depth
of 2km, close to the current maximum depth of extraction. Where
possible, estimate calculations were based on 1998 geological data
from mining companies. These were extrapolated for other areas of
the BIC where data was scarce or non-existent. The calculations
could be made with the necessary level of confidence due to the
remarkable continuity and uniformity of the PGM bearing
Working under the guidelines of the SAMREC Code Professor
Cawthorn estimated proven and probable reserves of platinum and
palladium at 203.3 million troy ounces, (6,323 tonnes) and 116.1
million troy ounces (3,611 tonnes), respectively. In addition to
these reserves, inferred resources were estimated at 939 million
troy ounces (29,206 tonnes) of platinum and 711 million troy ounces
(22,115 tonnes) of palladium.
In 2010, Professor Cawthorn published a supplementary paper in
which he demonstrated the level of confidence which can be applied
to his earlier estimates.
There is potential for these PGM resource estimates to be
increased further, both by mining the currently exploited ore
bodies at depths below 2 kilometres and by mining other PGM bearing
horizons in the BIC.
It can be inferred from the uniformity of the PGM reefs in the
upper 2 kilometres of the BIC that these ore bodies will continue
for considerable distance downwards, yielding similar grades of
PGM. Already, drilling programs are investigating the Merensky Reef
and UG2 horizons below 3 kilometres in depth, although considerable
exploration work will have to be performed before these potential
down-dip extensions can be classified as a PGM resource.
The additional investment necessary to work these deposits would
also be considerable, as working temperatures and transportation
costs increase with depth. However, technological advances in the
South African gold industry have now made deposits viable at a
depth of 4 kilometres and it is reasonable to expect that this
technology will be transferred to the PGM mines over time.
PGMs are also present in horizons which underlie the Merensky
and UG2 reefs in the BIC. These could be exploited when
shallower horizons have been worked out.
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