Red Metal has launched a significant phase of metallurgical testwork at its Sybella rare earths project in Queensland, starting six-metre-tall column leach tests designed to replicate the conditions of a full-scale commercial heap leach operation.
The tests are being run on slightly weathered rock and transitional ore from the project's Kary Zone deposit, 20 kilometres south of Mount Isa. The company plans to load crushed ore into 150-millimetre-diameter columns standing six metres high. In heap leaching, a chemical solution is trickled through the crushed ore to dissolve the valuable metals, which are then collected for recovery.
Red Metal managing director Rob Rutherford described the work as an important step toward validation. “This important next step far more closely replicates the compaction, percolation and acid distribution behaviour we expect inside a full-scale commercial heap leach,” he said.
The new program builds on an earlier two-metre column test program that the company said delivered neodymium extraction of up to 76 per cent and praseodymium extraction of up to 78 per cent from transitional ore. The prize for Red Metal is a low-cost processing route for what it describes as a geologically unique and potentially globally significant deposit. The company has defined a 4.795-billion-tonne inferred resource at Sybella, where the scale and potential for zero-strip mining make bulk-tonnage processing methods such as heap leaching an attractive option.
In a concurrent program, the company has also started two-metre column tests to assess a coarser crush size. Management says proving a coarser grind can still deliver strong recoveries could be a game-changer for the project's economics, lowering crushing costs and potentially allowing higher stacking heights on leach pads. Results from both the six-metre and the coarser-crush two-metre tests are expected to be reported as they become available. The work forms part of an ongoing prefeasibility study targeted for completion early next year.
Red Metal is also pursuing a “Big Copper” exploration strategy, targeting iron-oxide-copper-gold discoveries in Queensland's north-west. The company recently lodged 17 new tenement applications around its Gulf and Three Ways projects and is planning two fully-funded drill holes, with the Gulf hole partly funded by a $200,000 Queensland Government grant.