ore reserves and mineral resources 2011 report - Anglo American ...

SECURING OUR FUTURE
ORE RESERVES AND MINERAL RESOURCES
Exploration on prospecting permits awarded in 2007 is progressing
in line with the work-programme schedules and the environmental
management programmes submitted to the Government’s
Department of Mineral Resources. Most of these programmes are in
the fifth year of the five-year completion time frame and a three-year
extension will be sought on several of the prospects.
Foreign exploration continued in 2011, with the ongoing objective
of finding and defining projects of value to the Group. This included
projects in Brazil and Zimbabwe, with watching briefs in a number
of other promising geological provinces. Options to dispose of the
Company’s interests in Russia are being investigated. Greenfield
exploration in Brazil is ongoing, with the investigation of a number
of promising platinum prospects. Extensive exploration continues
on the Great Dyke in Zimbabwe in order to obtain information on
Mineral Resources, specifically in support of the mine extraction
strategy for the Unki Project.
MINERAL RESOURCES
No changes in terms of the basic principles relating to determining
Mineral Resource estimates were implemented during 2011. The
Mineral Resource evaluation and classification are reviewed and
signed off by a team of competent persons. Changes to further align
the minimum Mineral Resource widths with changes in stopesupport
methodology and mining equipment are envisaged for 2012.
Over the past two years exploration drilling results on the Platreef
have indicated a localised down-dip shallowing of the dip of the
orebody in the northern part of Mogalakwena. A conceptual pit
design has demonstrated that these Resources lying below the
current pit shell are economically viable to extract via an expanded
opencast operation. This has justified the extension of the reporting
depth from 450 m to 650 m below surface and results in an increase
of 71 million 4E ounces of Mineral Resources exclusive of Ore
Reserves. A significant proportion of these additional Resources is
classified as Inferred and additional drilling in 2012 is planned to
confirm structural and mineralisation continuity.
Investigations conducted in 2011 to determine maximum mining
depths related to virgin rock temperatures have been concluded.
A virgin rock temperature of 75° Celsius is currently considered to
be the limit to mining given anticipated technology, metal prices
and energy costs. Altogether 26.1 million 4E ounces of the affected
portions of the Inferred Mineral Resources within the mining rights
of Tumela Mine, Twickenham Platinum Mine and Ga-Phasha Project
are therefore reclassified as Mineral Deposit within the Amplats
portfolio. Amplats will review these deposits with changing
geological information, mining technology and metal prices.
As part of its ongoing management process, the Mineral Resource
Management (MRM) Department at Amplats has developed the
Basic Resource Equation to establish a consistent and auditable
6 ANGLO AMERICAN PLATINUM LIMITED 2011