Kantra’s Emily Star reserve reshapes Kanmantoo’s growth story

Kanmantoo reserve growth clears the depletion hurdle

Kantra Copper Limited (ASX:KAN) has added 31% to the Ore Reserve at its South Australian Kanmantoo mine despite depleting 1.4 million tonnes through mining over the year. The updated reserve stands at 5.2 million tonnes grading 0.85% copper and 0.20 grams per tonne gold, containing 44,000 tonnes of copper and 33,000 ounces of gold.

The increase includes a maiden 740,000-tonne reserve at Emily Star, grading 0.91% copper and 0.12g/t gold. Emily Star contributes 6,800 tonnes of contained copper and 3,000 ounces of gold, while Kavanagh and Nugent remain the larger components of the reserve base. The company said the estimate supports a positive pre-tax net present value at an 8% discount rate, although it did not disclose the absolute NPV in the announcement.

Emily Star moves from development project to scheduled production

The reserve update gives greater definition to the expansion already under way. Kantra began Emily Star portal construction during the September quarter, as reported in the Emily Star development start, and the new mine plan includes access through the 1010 Emily Star incline and a surface portal. A surface raisebore for ventilation is planned for early 2027.

The 2026 plan runs for 42 production months from July 2026 to December 2029. It schedules 5.69 million tonnes of total feed at 0.80% copper, including unavoidable dilution and material outside the declared reserve, with average feed of roughly 135,500 tonnes a month, or 1.63 million tonnes a year. That is below Kantra’s stated 2 million tonne annual ambition and is explicitly described as an inventory-based reserve schedule rather than a measure of the company’s production goal.

Resource expansion adds longer-term optionality

Kanmantoo’s Mineral Resource rose 22% to 27 million tonnes at 0.71% copper and 0.17g/t gold, containing 190,000 tonnes of copper and 150,000 ounces of gold. The update adds a maiden 520,000-tonne Critchley Resource and reflects 6.4 million tonnes of growth from drilling and resource definition work, partly offset by 1.2 million tonnes of mining depletion and 520,000 tonnes removed for having a low prospect of eventual economic extraction.

Emily Star’s resource increased 114% to 6 million tonnes, while Nugent grew 31% to 7.1 million tonnes. The result follows the Nugent drilling extension, which identified mineralisation below the previous resource model ahead of the estimate. Kantra says the broader resource remains open along strike and at depth, but converting that inventory into future reserves will require more drilling, mine development and economic assessment.

Costs and execution remain the harder part of the story

The reserve plan carries average on-site operating costs of A$82.77 per tonne milled, including A$60.82/t for mining, A$17.53/t for processing and A$4.43/t for general and administrative costs. Compared with the 2025 plan, processed tonnes rise 33%, development metres increase 59% and production drilling rises 24%, while average on-site operating cost per tonne increases 7%.

Kantra identifies copper prices, foreign exchange and mining costs as the main value sensitivities. Its base case uses US$4.20 a pound for copper, US$3,250 an ounce for gold and an exchange rate of US$0.70 per Australian dollar. Emily Star has not yet been mined underground, so its stopes use no operating reconciliation beyond the applied mining factors; the company also flags difficult ground conditions around two stopes beneath the Giant Pit and a pending approval for increased tailings storage capacity.

The enlarged inventory is therefore a useful test of execution, not simply a larger number on a resource table. Kantra must develop Emily Star, establish its ventilation circuit and sustain the existing mine’s productivity while controlling the cost base that the company’s own sensitivity analysis identifies as central to value. The next telling evidence will be whether underground development and production can approach the reserve schedule without the overbreak, approval and cost risks widening.