OPERATIONS Australia Region
ST IVES | AGNEW | GRANNY SMITH | GRUYERE | |||||||
Mining method | Open pit and underground | Underground | Underground | Open pit | ||||||
Operational infrastructure | St Ives has four underground mine areas and seven open pits contributing to the Mineral Reserve. There are seven underground mines and 16 open pits contributing to the Mineral Resource. Current ore stockpiles contribute 4.6% of the Mineral Reserve at the reporting date. There is a centralised administrative office and engineering workshop complex. | Agnew operates two underground mines, namely Waroonga and New Holland, now amalgamated into the Agnew One Mine
Complex. At Waroonga, ore is sourced from the Waroonga North, Kath, Fitzroy Bengal Hastings (FBH), Main and Kim lodes, accessed
via declines. New Holland mining occurs in four primary areas: Sheba South, Sheba, Cinderella and Himitsu. These areas are
accessed via declines. There are also centralised administrative offices, engineering workshops at Waroonga and New Holland, and
one active CIP processing plant (1.3Mtpa capacity). The plant capacity was increased to 1.35Mtpa at the end of 2022.
A hybrid renewable power plant was commissioned in 2019/2020 including solar, wind turbine, gas generator, battery power storage and diesel back-up power solutions. |
Granny Smith has one underground mine contributing to the Mineral Reserves and Mineral Resources. The Mineral Reserves do not include any open pits but one open pit contributes to the Mineral Resources. The mine has one ore stockpile in the LOM plan. Granny Smith has centralised administrative offices and engineering workshops. | The Gruyere JV Mineral Reserve comprises five open pits plus ore stockpiles. The Mineral Resource includes seven open pits and one underground deposit. The operation has a processing plant with a TSF and is supported by a power station with gas pipeline and power distribution lines. Borefields and water supply infrastructure, centralised administrative offices, engineering workshops, accommodation village, airstrip and road networks are all developed. Construction of a 12MW solar farm was completed in early 2022. | ||||||
Mineral processing and TSFs |
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The Agnew processing plant consists of a tertiary crushing circuit, followed by a two-stage ball milling circuit with gravity and a
conventional leach/CIP gold recovery circuit (1.3Mtpa capacity). The plant capacity was increased to 1.35Mtpa at the end of 2022.
Agnew's TSFs 1 and 2, and an adjoined above-ground paddock storage facility, are decommissioned. TSF 3 is an in-pit facility at the Redeemer pit, operational since it was commissioned in 2004. TSF 3 has been irregularly topped up since commissioning TSF 4. TSF 4 is an in-pit facility located at the Songvang pit and has a remaining LOM storage capacity of ~6.5Mt. All the Lawlers TSFs are closed and rehabilitated. |
Ore is processed at the milling/leach/carbon in pulp (CIP) processing plant under campaign milling conditions located 15km north-east of the Wallaby underground mine. Granny Smith operates a single TSF complex that comprises three compartments, known as cells 1, 2 and 3. Construction on a fourth cell (cell 4) was commenced in early 2022 next to cell 3 to provide additional tailings capacity for the rest of the LOM. Cell 1 has a High B ANCOLD consequence rating and was raised to its final permitted crest elevation of 448m relative level (mRL) in late 2016. It has a remaining LOM storage capacity of ~0.80Mt and is currently active. Cell 2 was raised to its final permitted crest elevation of 448.5mRL in 2012. This cell has a High B ANCOLD consequence rating, is filled to capacity and is harvested for paste fill. Cell 3 has a High B ANCOLD consequence rating and is currently being raised to an elevation of 434mRL (final permitted elevation of 437mRL). The cell 3F lift will be completed by March 2022 and will provide 1.97Mt capacity. |
All ore mined is processed in the Gruyere plant, which consists of primary crushing, semi-autogenous grind (SAG)/ball milling, gravity and carbon in leach (CIL) circuits. The processing plant was designed to 7.5Mtpa but subsequent work shows this can be increased to 9.5Mtpa for 2023 and then increased to 10Mtpa by 2024. The TSF perimeter embankment is constructed in a downstream manner (in stages) to enclose a surface area of ~203ha at stage 1 (starter) and 231ha at stage 6 (final). The TSF has a High B ANCOLD consequence rating and a remaining LOM storage capacity of ~78Mt. Studies are in progress to extend the existing TSF to increase capacity by 29Mt – 34Mt. |
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Brief history and regional geology | Orogenic greenstone gold deposits (hydrothermal) are hosted in several different styles of lodes. Although all Agnew deposits broadly occur at the intersections between structures and stratigraphy, there are subtle differences in alteration and mineralisation that are controlled in part by the local host rock chemistry. Mineralisation zones are discontinuous with short range predictability. | |||||||||
Exploration | The Australian mines continued to see the real benefits of consistent annual investment in extensional and near-mine exploration (US$56.6m invested in 2022 and between US$48m and US$76m invested per year over the past seven years). |
St Ives, Agnew, Granny Smith and Gruyere JV gold mines located in Western Australia
The Australia region operates a portfolio of predominantly low-cost, relatively long-life mines and has a strong pipeline of projects configured to drive Reserve replacement and life extension. The Gruyere JV, Granny Smith, St Ives and Agnew gold mines are located in Western Australia. The region’s summary Mineral Resource and Mineral Reserve estimates have been presented in the Group highlights section.
The Australian mines continued to see the real benefits of consistent annual investment in extensional and near-mine exploration (US$56.6m invested in 2022 and between US$48m and US$76m invested per year over the past seven years). Agnew and St Ives increased Mineral Resources and Mineral Reserves net of depletion, while Granny Smith provided an important offset to depletion despite a net Reserve reduction. Gruyere posted a net reduction in Mineral Reserves largely due to depletion with a small increase in costs also contributing to the reduction. The region is well positioned to deliver on near to medium-term growth options over time. The region again exceeded 1Moz gold production in 2022, repeating the achievement of 2021.
Far Southeast – Philippines
Gold Fields' 50% ownership in the Gruyere mine is held by Gruyere Mining Company Proprietary Limited, a wholly owned Australian subsidiary of Gold Fields. In 2022, Gruyere mined a combination of oxide, transitional and fresh rock, the latter becoming a major portion of the processing plant feed, and completed production with 315koz of gold produced. The attributable Gruyere JV Reserve decreased year-on-year by 0.2Moz (-9%), predominantly due to annual production depletion with an additional impact from cost increases.
Salient points
ATTRIBUTABLE MINERAL RESERVES
Measured and indicated
ATTRIBUTABLE MINERAL RESOURCES (EMR)
Proved and probable
Inferred
AUSTRALIA REGION MINERAL RESOURCES AND RESERVES 2022 – PDF 8MB |
Stuart J. Mathews
Executive Vice President:
Australasia Region
Stuart Mathews is an international mining professional with 26 years' experience having worked in Australia (Queensland, NSW, WA), Mexico and New Zealand. He has progressed through geology ranks to Geology Manager level and in the last 12 years worked in project development and general operations management to COO level. Stuart joined Gold Fields in mid-2013 initially at St. Ives, as then General Manager at Granny Smith Mine after which he became Vice President Operations: Australia. From February 1, 2017 Stuart took over the position of Executive Vice President: Australasia.