• Download centre
• Email this page
• Add/ View print basket

Zinc
estimates as at 31 December 2009

The Ore Reserve and Mineral Resource estimates were compiled in accordance with the Australasian Code for Reporting of Mineral Resources and Ore Reserves (The JORC Code, 2004) as a minimum standard. THE MINERAL RESOURCES ARE REPORTED AS ADDITIONAL TO ORE RESERVES.

The figures reported represent 100% of the Ore Reserves and Mineral Resources, the percentage attributable to Anglo American plc is stated separately. Rounding of figures may cause computational discrepancies.

Mining method: OP = Open Pit, UG = Underground. LOM = Life of Mine in years based on scheduled Ore Reserves.
For the polymetallic deposits, the tonnage figures apply to each metal.
Due to the uncertainty that may be attached to some Inferred Mineral Resources, it cannot be assumed that all or part of an Inferred Mineral Resource will necessarily be upgraded to an Indicated or Measured Resource after continued exploration.

⁽¹⁾

Black Mountain - Deeps: Broken Hill and the Deeps Ore Reserves and Mineral Resources are combined for reporting purposes as both deposits are geologically connected and make use of the same mining infrastructure. The decrease in Ore Reserves due to production has been partially offset through changed economic assumptions and updated resources modelling based on new information. The definition of Mineral Resources for Broken Hill and the Deeps is based on the same 2009 economic and financial parameters as used for the definition of Ore Reserves. Measured and Indicated Resources are estimated to contain 13.1Mt of material grading 41.3 g/t silver as a by-product. Inferred Resources are estimated to contain 7.3Mt of material grading 25.9 g/t silver as a by-product.

⁽²⁾

Lisheen: Changes are largely attributable to production as well as changes in the resource model (re-classification of Indicated Resources to Inferred Resources which are now not available for conversion to Ore Reserves) and sterilisation of ore due to back-filling on a retreat mining sequence. Mineral Resources are constrained by geological parameters (total sulphide content and ore thickness) and are quoted above a 6% ZnEq cut-off.

⁽³⁾

Skorpion: Production has been partially off-set by additional Ore Reserves derived through improved metal price assumptions and further geological information. An update of the geotechnical model for pit slope design is in progress. Mineral Resources are constrained by geological contacts and are defined using economic values and a cut-off grade (4% Zn). A major Mineral Resource model update, based on recent drilling information, is in progress.

⁽⁴⁾

Black Mountain - Swartberg: The Swartberg mine was placed on care and maintenance from January 2007. The Ore Reserves were removed from the mine plan and converted to Mineral Resources. Indicated Resources are estimated to contain 17.3Mt of material grading 35.0 g/t silver as a by-product. Inferred Resources are estimated to contain 24.5Mt of material grading 41.0 g/t silver as a by-product.

⁽⁵⁾

Gamsberg - North: The Gamsberg deposit has been renamed Gamsberg North to distinguish it from the recently discovered Gamsberg East deposit.

⁽⁶⁾

Gamsberg - North:The Ore Reserves published in 2008 were based on the 2000 Feasibility Study. In the period between 2000 and 2007 substantial change took place in the techno-economic environment of the Gamsberg project. Market, cost and exchange rate outlooks were considerably different while substantial changes had been made to the understanding of the resource and the mineral exploration potential of the greater Gamsberg environ. Advances in the understanding of the chemistry of manganese removal and improved leaching technology led to more technically robust and efficient metallurgical process design options, which needed investigation. Changes to the regulatory (mineral rights) and socio-economic environment (power, social costs, etc.) in South Africa needed to be incorporated into the project studies. A pre-feasibility study, which was initiated in late 2008, is not yet complete and therefore no Ore Reserves are reportable in 2009.

⁽⁷⁾

Gamsberg - North: Mineral Resource estimates have been updated following infill drilling campaigns carried out during 2008 and 2009 to both validate historic data as well as increase confidence in the Mineral Resources. Mineral Resources are constrained within mineralized horizons and within a pit shell and are reported above a cut-off grade of 3% Zn. During 2009, some 11kt of material with an average grade of 8% Zn were mined via the exploration adit and processed at the Black Mountain concentrator.

⁽⁸⁾

Gamsberg - East: Gamsberg East is located 4 km south east of Gamsberg North. Mineral Resources are constrained by geology and are quoted above a 7% Zn cut-off and are supported by a positive concept study for an underground mine undertaken in 2009. This study has recommended that Gamsberg East is incorporated in the Gamsberg North pre-feasibility study. As that study has not yet been completed, no Ore Reserves are currently reportable.

Audits related to the generation of the Ore Reserve and Mineral Resource statements were carried out by independent consultants during 2009 at the following operations: Black Mountain, Skorpion

Back to top