Near-mine (brownfields) exploration is key to Gold Fields' strategy as it offers one of the lowest-cost opportunities for adding ounces and growing cash-flow, particularly on a per share basis. The value in nearmine exploration lies in:
We believe brownfields exploration provides a robust platform for regional growth. In addition to growing Gold Fields' Mineral Resource and Mineral Reserve base, near-mine exploration also extends the life of the Group's existing assets and ensures that each region can continue leveraging its infrastructure.
In 2021, Gold Fields spent US$97m on near-mine exploration (excluding Asanko; 2020: US$75m), which supported a total of 335km of near-mine drilling (2020: 325km). We incurred the majority of this spending – US$59m (A$79m) (2020: US$50m (A$72m)) at our Australian mines, while US$10m was spent at Tarkwa and Damang.
Looking ahead to 2022, we have budgeted US$119m for near-mine exploration and Mineral Resource conversion across the business (excluding Asanko). Of this US$66m (A$86m) is budgeted to be spent at our Australian operations, US$31m at Salares Norte in Chile and US$11m at our Ghanaian mines, including study costs at Damang.
Following are details of the nearmine exploration activities at our managed operations:
ST IVES MINERAL RESERVES
At St Ives, total 2021 near-mine exploration spend amounted to A$35.1 (US$26.4m). A total of 114,330m were drilled during the year. The mine’s Mineral Reserves decreased by 9% to 2.4Moz and Mineral Resources declined by 2% to 4.9Moz. In 2021, extensional exploration targeted additions to the Invincible, Neptune and Hamlet complexes, with significant growth in both Mineral Resources and Mineral Reserves in the Invincible complex.
AGNEW MINERAL RESERVES
We spent A$24.5m (US$18.4m) on near-mine exploration at Agnew during 2021, drilling 80,517m. The mine's Mineral Reserves increased by 10% to 1.0Moz while Mineral Resources increased by 7% to 3.4Moz. Exploration at Agnew successfully targeted extensions of both the Waroonga and New Holland mineralised systems. The commitment to exploration at Agnew, particularly over the past six years, has contributed to the site exceeding 1Moz of Mineral Reserves for the first time since 2012.
GRANNY SMITH MINERAL RESERVES
Total near-mine exploration spend at Granny Smith amounted to A$17m (US$12.7m) in 2021, with a total of 72,947m drilled during the year. The mine's Mineral Reserves increased by 2% to 2.2Moz and Mineral Resources also improved by 2% to 8.1Moz. Drilling activity focused on infill and extensions to Zones 135 and 150 at Wallaby.
GRUYERE MINERAL RESERVES (100%)
Gold Fields spent A$2.4m (US$1.8m) on near-mine exploration at Gruyere during the year, drilling 12,425m.
The mine's attributable Mineral Reserves (50% basis) increased by 28% to 2.2Moz while attributable Mineral Resources increased by 10% to 3.7Moz. A two-phase exploration deep drilling programme beneath the Gruyere pit was completed in 2021. We also completed 13 diamond holes, totalling 12,425m. Drilling was designed to test for depth and strike extensions of the Gruyere porphyry 400m below the Stage 5 pit design.
TARKWA MINERAL RESERVES
Gold Fields spent US$3.0m in nearmine exploration at Tarkwa during the year, drilling 9,801m. Tarkwa's Mineral Reserves decreased by 5% to 5.8Moz, while Mineral Resources declined by 8% to 9.8Moz.
Exploration activities in 2021 focused on palaeoplacer potential, delineating new Mineral Resources and upgrading known Mineral Resource areas. This will continue into 2022.
DAMANG MINERAL RESERVES
The Group spent US$3.6m on nearmine exploration at Damang during the year, drilling 10,461m. The mine's Mineral Reserves decreased by 38% to 637koz and Mineral Resources declined by 20% to 4.6Moz. Most of the exploration focused on earlystage (target definition) programmes at Epieso and Tomento East, as well as infill drilling of the Damang Mini- Cutback volume in support of the mine's next-pit expansion study.
SOUTH DEEP MINERAL RESERVES
Gold Fields spent US$0.5m on near-mine exploration at South Deep in 2021, drilling 3,117m. The mine's Mineral Reserves decreased by 8% to 32.2Moz and Mineral Resources declined by 2% to 61.2Moz. Exploration drilling at the mine focused on underground areas ahead of the destress echelon.
CERRO CORONA MINERAL RESERVES
US$3.4m was spent on nearmine exploration at Cerro Corona during the year, drilling 8,005m. The mine's Mineral Reserves decreased by 19% to 1.1Moz and Mineral Resources declined by 11% to 1.7Moz. We completed two in-pit diamond drilling campaigns in 2021, focusing on geology, geotechnical, geometallurgical and deep drilling exploration holes.
SALARES NORTE MINERAL RESERVES
Gold Fields spent US$27.7m on near-mine exploration at Salares Norte during the year, drilling 23,848m. The mine's gold Mineral Reserves maintained at 3.5Moz while gold Mineral Resources increased by 4% to 4.1Moz. Most of the spend was on district scale exploration and primarily focused over the Horizonte Project, where 13,808m of diamond drilling was executed over multiple targets.