The Tropicana partners AngloGold Ashanti Australia (AGAA) and Independence Group have committed to Long Island.
Long Island has been driven by developing a more cost-effective way to mine waste.
It involves using a strip-mining approach that minimizes waste haulage distances by using in-pit backfill, rather than trucking the material long distances to surface waste dumps.
The completed Tropicana pit will be used as the first backfill location.
Phase One of Long Island comprises mining of the Havana South and Boston Shaker pits ahead of the next decision point in 2020, on whether to start stripping the Havana main pit, and the third decision point in 2022, on whether to commence with the final stages of the Havana Main pit.
The phased approach provides optionality and the flexibility to adjust to prevailing economic conditions.
The full Long Island strategy adds 2.1 million oz to Tropicana’s business plan, extending mine life by approximately seven years to 2027.
The project value has been enhanced by the decision to install an additional 6 MW ball mill in the processing plant, enabling throughput to be matched to the increased mining rate and improving gold recovery by up to 3% to approximately 92%.
Grade streaming, which prioritises the processing of higher-grade ore and stockpiling lower-grade material for processing at a later date, has resumed at Tropicana and will continue through 2018 and 2019.
Gold production (100%) is forecast to be between 478,000 oz and 492,000 oz next year and between 530,000 oz–548,000 oz in 2019.
“This project is in line with our approach of developing cost-effective brownfield projects with attractive payback periods that extend life and improve margins,” comments AngloGold Ashanti’s senior VP Australia Michael Erickson.
“The project validates the innovative ideas developed by our site team and technical specialists, and also gives us an excellent base from which we can investigate adding additional value through underground mining opportunities and regional exploration," he continues
Gold production over Tropicana’s remaining life of mine is now forecast to be about 4 Moz.
This does not include potential future underground production from mineralisation at the Boston Shaker ore body, which remains open at depth.
Following a scoping study, which is currently underway, a prefeasibility study on underground mining will begin in 2018.
Tropicana lies about 330 km east-northeast of the Western Australian town of Kalgoorlie.
AGAA, which manages the mine, owns a 70% stake and Independence Group NL has the remaining 30%.
The Long Island strategy is underpinned by continued exploration success, evidenced by another increase in the ore reserve to 66.59 Mt grading 1.91 g/t for a total of 4.08 Moz.
This represents an increase of 280,000 oz over the past year, even after depletion of about 550,000 oz is taken into
Including gold produced to date, Tropicana has delivered a 72% increase in Ore Reserves since the Tropicana project was approved in November 2010.
Mining rates at Tropicana have been successfully increased over the past year to more than 90 Mtpa with the addition last year of a 600 t face shovel, de-risking the increase to the Long Island mining rate of between 95-107 Mtpa.
The mining rate will peak at 107 Mtpa in 2019 and continue at that rate for about four years until the bulk of the Havana pit is mined.
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