Red Metal Limited has stepped up metallurgical work at its Sybella rare earths project in northwest Queensland, with large-scale weak-acid column heap leach tests now underway on coarsely crushed granite-hosted ore.
The test program is designed to replicate real-world heap leach conditions. It follows earlier bottle-roll optimisation studies that delivered encouraging rare earths extraction using low-pH, ambient-temperature sulphuric acid. Results from the column leach trials are expected early next year and will provide critical inputs for mine scoping and economic studies.
Sybella is emerging as a standout rare earths opportunity, targeting the shallow weathered profile of the Sybella Batholith – a large A-type composite granitoid complex located just 20 kilometres from Mt Isa in Queensland’s prolific Cloncurry district. The partially weathered granite extends for more than 12 kilometres in length and three kilometres in width, underscoring the sheer scale of the system.
Notably, Red Metal says the bulk of the rare earth mineralisation tends to occur in soluble fluoro-carbonate minerals that are well suited to heap leach extraction – a processing scenario the company has dubbed “metallurgical nirvana”.
The current column leach tests have been based on nine 85-millimetre diamond core samples recently drilled from the project’s Kary Zone. Alongside the leaching studies, Red Metal is also advancing ion exchange work, detailed comminution testing and planning infill drilling to support future resource upgrades.
Red Metal Limited managing director Rob Rutherford said: “We are excited to be progressing the large column leaching on coarsely crushed Sybella ores. This important next step best simulates a real-world heap leach setting and aims to repeat the strong rare earth extractions shown in earlier bottle roll testing.”
Earlier metallurgical results highlighted the quality of Sybella’s rare earths basket, with about 21 per cent of the project’s in-situ value attributed to high-demand heavy rare earth elements such as dysprosium and terbium. Outside of China, heavy rare earths production is limited, with northern WA’s Browns Range one of the few comparable operations.
The company believes Sybella’s granite-hosted setting is unusual for rare earths deposits, with a natural pH of about 3.5 and low impurity levels. This combination is seen as favourable for scalable, low-cost heap leach mining of the soft weathered material near surface.
Bottle-roll leach testing on weathered granite from the Kary Zone has already identified a pH sweet spot between 2.0 and 2.5, delivering substantial recoveries of high-value magnet rare earth oxides such as neodymium and praseodymium while keeping acid consumption low.
The Sybella granite is no stranger to mining. Historically, parts of the batholith were quarried for dimension stone used in construction and gravestones, with large blocks extracted and later abandoned across the site. Red Metal now sees this legacy as proof of the granite’s favourable mechanical properties and shallow weathering profile – qualities that could support low-cost mining and crushing for heap leach operations.
The project also benefits from excellent infrastructure, with access to power, water and labour thanks to its proximity to Mt Isa. Add in Sybella’s enormous scale – an estimated 4.8 billion tonnes grading 302 parts per million (ppm) neodymium and praseodymium, coupled with 28ppm dysprosium and terbium – and the project has the hallmarks of a long-life, low-cost rare earths operation.
With column leach results on the horizon and pre-feasibility studies targeted for 2026, Red Metal appears to be positioning Sybella as a potential Australian trailblazer in magnet and heavy rare earth production.
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