Mineral Resource & Ore Reserve
AngloGold Ashanti strives to actively create value by growing its major assets – For further information see Mineral Resource and Ore Reserve – summary.
This drive is based on active, well-defined brownfields and greenfields exploration programmes, innovation in both geological modelling and mine planning, and continual optimisation of the asset portfolio. Ensuring a viable Mineral Resource and Ore Reserve pipeline will enable delivery of sustained value-adding growth in the long term.
For detailed information, refer to AngloGold Ashanti's Mineral Resource and Ore Reserve report 2021 PDF, 34.2MB
Mineral resource – Gold
The AngloGold Ashanti Mineral Resource reduced from 124.5Moz in December 2020 to 123.2Moz in December 2021. This annual net decrease of 1.3Moz includes depletion of 2.9Moz, the relinquishment of the lease for Obuasi’s Anyankyirem open pit of 0.4Moz, changes in economic assumptions of 2.3Moz and other factors of 1.4Moz (including the write-off of 0.6Moz for AGA Mineração Nova Lima Sul). This decrease is partially offset by additions due to exploration and modelling changes of 5.7Moz. The Mineral Resource was estimated using a gold price of $1,500/oz, unless otherwise stated (2020: $1,500/oz).
|Mineral Resource as at 31 December 2020||124.5|
|Disposal||At Obuasi, the Anyankyirem open pit mining lease was relinquished.||(0.4)|
|Silicon||A maiden Mineral Resource was declared after the completion of a positive conceptual study based on the greenfield exploration success.||3.4|
|Geita||Increase due to ongoing grade control and successful exploration activities. Following a review of mining cost for 2021 the resultant reduction in cost led to further increases.||0.9|
|Sunrise Dam||Increase due to ongoing advanced grade control and exploration activities partially offset by minor local changes in gold price and an overall increase in costs||0.7|
|Kibali||Changes were largely as a result of exploration, with gains seen from the open pits, specifically from Oere, Pamao, KCD and Gorumbwa as well as from the initial Inferred Mineral Resource definition of the 11000 lode in the underground.||0.6|
|Other||Additions less than 0.5Moz||0.3|
|Obuasi||Changes primarily due to model changes in the historic mining areas in the north of the mine which accounted for an overall reduction.||(2.2)|
|Iduapriem||New grade control drilling at Block 3W resulted in a decrease in model grade and re-interpretation of the intrusives in the deeper portions of Blocks 7 and 8 resulted in further losses. These were partially offset by lower costs resulting from a new long-term contract resulting in additions.||(0.6)|
|Other||Reductions less than 0.5Moz||(1.1)|
|Mineral Resource as at 31 December 2021||123.2|
The AngloGold Ashanti Ore Reserve increased from 29.7Moz in December 2020 to 29.8Moz in December 2021. This annual net increase of 0.1Moz includes additions due to exploration and modelling changes of 4.1Moz. This increase was partially offset by depletion of 2.6Moz and reductions due to other factors of 1.4Moz. The Ore Reserve was estimated using a gold price of $1,200/oz, unless otherwise stated (2020: $1,200/oz).
|Ore Reserve as at 31 December 2020||29.7|
|Iduapriem||The net increase is primarily due to the decrease in costs resulting from signing a new mining contract and operational changes.||0.9|
|Geita||The significant increase is mainly due to ongoing drilling exploration success resulting in larger pit designs. The open pit shell and underground slope design changes contributed to an increase of 27% and 3% to the Ore Reserve respectively.||0.8|
|Kibali||The increase in Ore Reserve was primarily as a result of the conversion of the 3000 and 9000 lode extensions in the KCD underground, and the addition of the Oere pit and growth in the Pamao pit due to exploration successes. The price used for pit optimisation at Pakaka and Gorumbwa also changed from $1,000/oz to $1,200/oz which contributed to the increase seen.||0.5|
|Sunrise Dam||The increase in the reported Ore Reserve is due to exploration success and a revised methodology for underground stope optimisation offset by more conservative extraction ratios and increased unit costs.||0.4|
|Other||Additions less than 0.3Moz||0.5|
|Obuasi||Operational changes primarily associated with design reviews in historically mined areas to eliminate low confidence stopes resulted in a net decrease which was partially offset by methodology changes.||(0.4)|
|Other||Reductions less than 0.3Moz||(0.0)|
|Ore Reserve as at 31 December 2021||29.8|
The AngloGold Ashanti Mineral Resource of 4.39Mt (9,677Mlb) remained unchanged between December 2019 and December 2020.
|Mineral Resource as at 31 December 2020||4.39||9,677|
|Quebradona||Decreases resulted from the remodelling of the orebody including three new drill holes.||(0.13)||(293)|
|Mineral Resource as at 31 December 2021||4.26||9,384|
The AngloGold Ashanti Ore Reserve increased from 1.39Mt (3,068Mlb) in December 2019 to 1.41Mt (3,105Mlb) in December 2020. This gross annual increase of 0.02Mt is due to optimisation of the production levels.
|Ore Reserve as at 31 December 2020||1.41||3,105|
|Quebradona||Result of an update in the Mineral Resource model due to three new drill holes, in addition to an upgrade in Mineral Resource classification based on conditional simulation.||0.07||145|
|Mineral Resource as at 31 December 2021||1.47||3,250|
For detailed information, refer to AngloGold Ashanti's <RR>21 Mineral Resource and Ore Reserve report 2021