Rio2 hits afterburners for final Chilean gold mine push

Rio2 Limited has picked up the pace at its flagship Fenix Gold project in Chile’s Atacama Region, revealing that the final mine build phase is well and truly underway. 

With construction pegged at 63 per cent complete as of the end of September, the new mine remains firmly on track for a first gold pour in January next year. Every long-lead item has now been delivered, so the project can move quickly from build to production early next year.

The TSX-listed company says the US$235 million (A$355 million) development remains both on time and on budget. To date US$86.7 million has been spent on the mine and processing facilities in line with the budgeted US$86.6 million - an increasingly rare feat in the current construction climate.

Perched high in Chile’s legendary Maricunga gold belt at a lofty 4500 metres, the Fenix Gold project is already a monster in the making. The deposit spans 2000 hectares and hosts a staggering 389 million tonnes of ore grading 0.38 grams per tonne (g/t) gold, for a total of 4.8 million measured and indicated ounces.

The operation will run on a simple, low-cost heap leach setup designed to deliver serious returns. Heap leaching is a system of piling ore on a thick polyethylene pad and spraying it with a chemical solution to dissolve and extract the gold.

During its first 12 years, Fenix is tipped to produce about 91,000 ounces of gold a year at 0.54g/t gold, before averaging 82,000 ounces annually at 0.48g/t across its full 17-year life. A 2023 feasibility study valued the project at US$210 million (A$333 million) after tax, based on a conservative US$1750 (A$2643) per ounce gold price and a tidy 3.5-year payback.

Updated modelling in 2024 assuming a US$2250 (A$3400) per ounce gold price shows the project’s net present value soaring to US$546 million (A$824 million) and the internal rate of return ballooning to 64 per cent. However, with the gold price now north of US$4000 (A$6000) an ounce - and almost double the newer assumptions - the numbers are now looking nothing short of explosive.

On the ground, the project’s centre piece - the heap leach pad – has now been lined with 12.7 hectares of high-density polyethylene, which is enough to handle the first six months of operations, while another 10 hectares are on the way before year’s end. Almost 22,000 cubic metres of crushed rock has also now been spread across the pad as over liner material, cloaking 8.5 hectares of pad.

Mining kicked off in August from the company’s Fenix Central and Fenix South starter pits, with 87,000 tonnes of the first ore already sitting on the pad at an average grade of 0.45 grams per tonne gold, equating to 1,260 ounces in inventory.

Meanwhile, the project’s pregnant leach solution (PLS) pond has been completed and water filling began in late September. Pressure testing and leach circuit commissioning is expected to follow next month. Haul road 1 has been fully built and haul road 4 is all but complete, connecting the southern orebodies directly to the processing area.

At the adsorption-desorption-recovery (ADR) plant all the electrical sand diesel generators have been installed along with the key acid wash and desorption reactors. 

The ADR is the heartbeat of production and where a complex gold extraction circuit turns the liquid gold into a solid metal. The pregnant cyanide solution, which is laden with gold, is run through tanks filled with activated carbon. The gold molecules stick onto the surface of the carbon particles, while the barren solution exits the circuit to be reused.

From there the fully loaded carbon is then “washed” with a hot caustic solution that strips the gold into a more concentrated form, which is then sent to the electrowinning tank to be plated on steel wool. The plated wool is finally smelted in a furnace to produce solid gleaming doré bars.

Rio2 says more than 1,500 of its people - including contractors - are overwhelmingly Chilean, with 44 per cent hailing from the local Atacama region and 13 per cent women, underscoring the project’s strong regional engagement credentials. 

Almost 1.9 million work hours have now been clocked on site, with only three lost-time incidents across the 11-month build window.

Beyond the build, exploration and grade-control drilling at the company’s Fenix South wrapped up in July, with early reconciliation showing the new grade-control model lining up almost perfectly with the reserve model.

Upcoming milestones include leach commissioning in November, plant commissioning by December and the first gold pour in January 2026, followed by a pre-feasibility study on the mine’s expansion plans in the first quarter of next year.

In September, Rio2 made a game-changing move, inking deals with two separate desalinated water providers – the rarest of commodities in the Atacama Desert – that could unlock the key to tripling output at its Fenix Gold mine to a massive 300,000 ounces of gold a year. 

Under the twin agreements, each supplier will roll out concept studies to explore supply options and map the pipeline infrastructure needed to pump desalinated water up to the mine. Once the studies are complete, Rio2 will choose its preferred partner to push ahead with a full feasibility program and a joint development plan.

With the finish line now in sight, Rio2 looks to be roaring into 2026 with the wind at its back and gold in its sights. The combination of disciplined project delivery, high-grade starter pits and a simple, proven heap leach circuit has the company poised to hit production without missing a beat or blowing the budget. 

And with gold prices smashing record highs, the economics of Fenix Gold appear to be shifting from impressive to extraordinary.

Is your ASX-listed company doing something interesting? Contact: matt.birney@businessnews.com.au