Grange Resources has given the green light to a new underground mine at its Savage River iron ore operation in northern Tasmania, a move designed to extend the life of the site and keep its pellet production running into the mid-2030s.
In a filing to the Australian Securities Exchange on Wednesday, the Perth-based miner said its board had made a final investment decision for the North Pit Underground Project. The decision comes as the current open-pit mine plan winds down, and the company expects first ore from the underground operation in the first quarter of 2027.
The project is part of a staged approach to the site's future. Grange says the underground extension could sustain pellet supply until 2035, while a larger “block cave” expansion—a mining method that extracts ore by undercutting a block of rock and letting it collapse—remains a possibility for beyond 2040. That larger option would require significantly more upfront capital, so the company is deferring that decision until later.
What the numbers say
Grange provided key financial metrics for the project, based on a base-case iron ore price of US$90 per metric ton for 62% iron fines—a widely used benchmark grade. At that price, the company estimates an after-tax net present value (NPV) of AU$357 million, discounted at an 8.3% real rate, and an internal rate of return (IRR) of 43%.
In plain English, NPV is a way of measuring whether a project is worth more than it costs, taking into account the time value of money. A positive NPV means the project is expected to generate value above its cost of capital. The IRR is the annualized rate of return the project is expected to earn. A 43% IRR is high, suggesting the project could pay back well above the company's cost of capital—but only if the price and cost assumptions hold up over the life of the mine.
These figures are sensitive to changes in assumptions. Iron ore prices are notoriously volatile, and long-dated price expectations can shift quickly. A small change in the assumed price or in the discount rate can have a large impact on the NPV, because the project's cash flows stretch over many years.
Why the staging matters
Grange's decision to commit to the underground extension now, while deferring the block-cave expansion, is a deliberate strategy to limit risk. By locking in a smaller, more manageable investment today, the company avoids tying up large amounts of capital in a project that might not be viable if iron ore prices weaken before 2027.
At the same time, the staged plan leaves the door open for a longer-life expansion if market conditions remain favorable. This optionality is valuable: it allows Grange to wait and see how prices evolve before making a much bigger bet.
For investors, the key takeaway is that the project's value is highly dependent on iron ore prices and the discount rate used to value future cash flows. While the modeled returns look strong, they are not guaranteed. The company's ability to execute on schedule and control costs will also be critical.
What it means for investors
Grange is essentially asking investors to believe in AU$357 million of value built on a US$90 per ton iron ore price and a long ramp-up to first ore in early 2027. Projects with very high modeled returns can look stable on paper, but their valuation can swing a lot in practice because small changes in assumptions ripple through years of future cash flows.
Investors should also consider the broader context. Iron ore is a key ingredient in steelmaking, and its price is influenced by global demand, particularly from China, the world's largest steel producer. Any slowdown in Chinese construction or manufacturing could weigh on prices, while supply disruptions elsewhere could push them higher.
Grange's move is part of a wider trend in the mining sector, where companies are increasingly looking to extend the lives of existing operations rather than develop new greenfield projects. This approach can be less risky and more capital-efficient, but it also means the company's fortunes remain tied to a single commodity.
For everyday investors, the story is a reminder that mining projects are long-term bets with significant uncertainty. The high IRR looks attractive, but it is based on assumptions that may not hold. As always, diversification is key—investing in a single miner like Grange carries more risk than a broad-based fund that spreads exposure across many companies and commodities.
Grange's announcement comes amid a mixed period for miners, with some miners sliding on inflation data and others seeing renewed interest, such as the gold miners ETF pullback drawing investors back in. The iron ore market itself remains a key watchpoint for the sector.
As the project moves forward, investors will be watching for updates on construction progress, cost overruns, and any changes to the company's price assumptions. The first ore in 2027 is still a few years away, and a lot can change in that time.
