TBO is located in the highly prospective Yandal Belt and the Agnew-Wiluna Belt in the North Eastern Goldfields of Western Australia. Operations are centred on the Thunderbox Open Pit and CIL gold treatment plant; located 45km south of the town of Leinster in Western Australia and immediately adjacent to the sealed Goldfields Highway.
Thunderbox mineralisation is hosted in an intermediate intrusive porphyry, in the hangingwall of the Thunderbox Shear Zone. The shear zone is over 200m wide and the mineralisation is predominantly confined to the intrusive porphyry, which is upto 80m in width. The mineralisation is cut and offset by a major fault known as the Gap Fault. This fault is what separates the two key domains, Zone A and Zone C.
Saracen acquired TBO in 2014 and commenced commercial production in 2016. TBO includes the Thunderbox Project (comprised of the Thunderbox, Rainbow and Otto Bore gold deposits), the Kailis Project (comprised of the Kailis Stage 1 & 2 gold deposits), the Bannockburn Project (comprised of the Bannockburn and North Well gold deposits) and the Waterloo Project (comprised of the Waterloo and Amorac nickel deposits).
The Thunderbox processing facility, which was recommissioned during 2015, has a nameplate capacity of 2.5Mtpa, although during FY2019 the processing plant operated above nameplate capacity at 2.8Mtpa. Existing infrastructure comprises a ~340 person accommodation village, an airstrip, power infrastructure, a spur to the Goldfields Gas Pipeline, bore field water supply and telecommunication services.
In FY2020, gold production will be principally sourced from the Thunderbox C Zone open pit and Kailis Stage 2 open pit. Some production will be sourced from the developing Thunderbox underground mine and various stockpiles. Production guidance at TBO for FY2020 is 160,000 to 170,000ozs.
Saracen’s business plan for TBO over the next 2 years comprises:
• Delivery aligned to meet or exceed the 7 year production outlook;
• Maintaining base load production from the Thunderbox C Zone open pit whilst assessing opportunities for higher grade satellite top up feed;
• Continuing mining the Kailis Stage 2 open pit contributing higher grade ore feed to optimise ore blending opportunities at the Thunderbox mill;
• Continuing developing the Thunderbox underground mine, deliver the finalised Thunderbox underground Feasibility Study;
• Commencing operations at the nearby Otto Bore satellite open pit; • Commencing pre-strip at the D Zone open pit cutback;
• Continuing working on the Life of Mine strategy of base load feed from various sources adjacent to the TBO mill with bolt on growth options to increase production;
• Pursuing the optimal operation of the Thunderbox mill to maximise production and cash flow generation;
• Funding all project development through internal cash flow generation;
• Commencing major exploration focus on near mine extensions – the best spot to find a new mine is at an existing mine;
• Growing the Reserve base;
• Continuing the trajectory of reduced AISC; and
• Generating sustaining cash flows.