AngloGold to Increase Production at Tropicana

AngloGold Ashanti Australia (AGAA) has announced that the joint-venture partners at the Tropicana mine in Western Australia have approved Phase One of a strategy to increase production in the medium term and extend mine life. The strategy involves a strip-mining approach that minimizes waste haulage distances by using in-pit backfill, rather than trucking of material to surface waste dumps. Phase One of the strategy calls for mining of the Havana South pit, south of the existing Tropicana pit, and a cutback of the Boston Shaker pit, north of the Tropicana pit, that will use the completed Tropicana pit as the first backfill location. The Tropicana gold mine is located 330 km east-northeast of Kalgoorlie, Western Australia, and is owned by AGAA (70% and manager) and Independence Group NL (30%).

The new mining strategy adds 2.1 million oz to Tropicana’s business plan and will extend mine life by approximately seven years to 2027. The project value has been enhanced by a decision to install a 6-MW ball mill in the processing plant, enabling throughput to be matched to the increased mining rate. The throughput rate will be lifted to approximately 8.1 million mt/y, and, through a reduction in grind size, baseline metallurgical recovery will be improved by as much as 3% to approximately 92%.

The new mill is scheduled to be commissioned in the fourth quarter of 2018. The site has adequate power generation capacity to cater for the additional mill, and no further infrastructure is required. Tropicana gold production is forecast at between 478,000 oz and 492,000 oz in 2018 and between 530,000 oz and 548,000 oz in 2019. Total gold production over Tropicana’s remaining mine life is forecast at about 4 million oz. This does not include potential future underground production from mineralization at the Boston Shaker orebody, which remains open at depth. A prefeasibility study on underground mining at Boston Shaker will be commissioned in 2018.

The study will include infill drilling and mining studies. Successful development of an underground mine at Boston Shaker has the potential to contribute high-grade ore to the processing plant from 2021 onward. The ore reserve at Tropicana now stands at 66.59 million mt grading 1.91 g/mt for a total of 4.08 million oz. This represents an increase of 280,000 oz over the past year, even after mining depletion of about 550,000 oz. Including gold produced to date, Tropicana has delivered a 72% increase in ore reserves since the project was approved in November 2010.

Mining rates at Tropicana have increased over the past year to more than 90 million mt/y. The mining rate is planned to peak at 107 million mt/y in 2019 and continue at that rate for about four years until the bulk of the Havana pit is mined. To achieve the additional material movement, a second 600-mt shovel and up to five additional Caterpillar 793 trucks and supporting ancillary equipment will be added to the fleet. The additional fleet will be provided by Macmahon Holdings as part of the mining contract at the site.

As featured in Womp 2018 Vol 01 -