The Tropicana Mine, the first greenfields gold discovery to be brought into production in Australia for more than a decade, poured first gold on September 26, 2013, ahead of schedule and on budget.
Innovation has been incorporated into the design of Tropicana’s mining and processing systems, from the start of exploration through to environmental management and closure planning.
The mine was officially opened in March 2014 by the then Western Australian Minister for Mines and Petroleum, the Hon. Bill Marmion, and produced its 1 millionth ounce on schedule in December 2015, just over two years after pouring first gold, and its 2 millionth ounce nearly three years later in January 2018.
The large-scale, open pit and soon-to-be combined underground operation, features a modern processing plant which uses conventional carbon-in-leach technology and includes high pressure grinding rolls (HPGR) for energy-efficient comminution. A second ball mill was added to the grinding circuit in 2018 to optimise the circuit, improve metallurgical recovery and match mine output.
Mining is carried out under an alliance-style contract with Macmahon.
Production increased by 5% in 2018 due to higher mill feed grades and higher mill throughput to 625,000oz (AGAA 70%) at 2.01 g/t.
The second 6MW ball mill was commissioned ahead of schedule in November 2018 with full ramp-up achieved within a week.
The additional ball mill is expected to lift annual throughput to 8 Mtpa and, through a reduction in grind size, to improve baseline metallurgical gold recovery by up to 3% to approximately 92%. The Long Island mining sequence was further optimised during 2018, with mining rates stabilising at approximately 95 Mtpa. Grade streaming continued in 2018 with preferential processing of higher grade ore while low-to-medium grade ore was stockpiled. Mining during 2018 focussed on the Havana South, Havana 3 and Tropicana 2 pits. It is anticipated that mining of the Tropicana pit will be completed in the first half of 2019, while mining will begin in the Boston Shaker open pit cutback 4 during the second half of the year.
In late March 2019 the formal go ahead was given to the Boston Shaker Underground Project after a feasibility study confirmed it was technically and financially viable with an anticipated IRR of 39% for a capital investment of $79.3 million (100%).
Boston Shaker will contribute higher grade mill feed, resulting in an improved gold production profile and enhanced cash flow. Importantly, the underground mine will provide improved cash flow during 2021-23 when the mine includes periods of higher waste stripping in the Havana open pit.
Ore from the underground mine will enable Tropicana gold production to be maintained at between 450,000-500,000 ozpa (100%) over the next five years, lifting the average to 480,000 ozpa over the five year period.
The project will commence in the June quarter 2019 and first gold is scheduled for the September quarter in 2020.
The Feasibility Study was based on the mining of 6.58 million tonnes, grading 3.84 g/t, assuming the systematic conversion of Mineral Resources to Ore Reserves over the life of the mine.
The average underground mining rate will be approximately 1.1 Mtpa (including development) over an eight year mine life to 2026 to produce a total of 732,000 oz. Mining methods will comprise conventional mechanised mining and underhand sublevel open stoping.
The proposed mining fleet comprises: two jumbos, two production drills, three remote-capable loaders and four trucks.
An underground mining contract was awarded to Macmahon, the mining alliance partner at Tropicana since commencement of open pit mining in 2012. As Macmahon will operate both the open pit and underground mines significant operational and management synergies will be delivered.
The portal will be located in the completed Tropicana pit, to minimise interaction between the open pit fleet working in the Boston Shaker pit and underground equipment.