How Red Metal’s Sybella Tests Unlock Low-Cost Rare Earth Extraction at Mild pH
Red Metal Limited’s latest leach test results from the Sybella rare earths discovery confirm promising low-cost processing potential using mild acid conditions, significantly reducing impurities and acid consumption. The findings pave the way for definitive column leach tests and expanded resource evaluation.
- Optimised leach tests achieve strong rare earth extraction at pH 2.0–2.5
- Significant reduction in iron impurities through natural precipitation in heap leach
- Lower acid consumption rates improve economic viability
- Upcoming column leach tests to provide definitive processing data
- Expanded drilling increases near-surface resource potential
Optimising Rare Earth Extraction at Sybella
Red Metal Limited has announced a significant advancement in the processing potential of its Sybella rare earths discovery, located near Mount Isa in Queensland. Recent optimisation leach tests on drill samples from the eastern Kary Zone demonstrate that ambient temperature sulphuric acid at a relatively mild pH range of 2.0 to 2.5 can effectively extract key magnet rare earth oxides (MREO) such as neodymium, praseodymium, terbium, and dysprosium. This is a notable improvement over earlier test work which suggested stronger acid conditions were necessary.
The company’s research also uncovered a natural mechanism within the heap leach process that precipitates iron impurities as iron oxides, specifically goethite, thereby significantly reducing downstream purification costs. This iron removal occurs as the leach liquor gradually neutralises, allowing the acid strength to be lowered over time without compromising rare earth extraction efficiency.
Economic and Processing Implications
The optimised pH conditions not only maintain strong rare earth recoveries, ranging from 76% to 81% for neodymium and praseodymium, but also reduce acid consumption to between 17 and 22 kilograms of sulphuric acid per tonne of ore. Aluminium and iron impurity extractions are kept low, with iron extraction dropping from 13% in previous tests to around 2% at the optimised pH. This combination of lower acid use and impurity removal enhances the economic feasibility of heap leach processing for the weathered granite ores at Sybella.
Red Metal’s Managing Director, Rob Rutherford, highlighted the importance of these findings, noting the potential for a low-cost, scalable heap leach operation that leverages the deposit’s unique granite-hosted mineralogy. The company plans to commence definitive column leach tests on recently drilled diamond core samples to better simulate heap leach conditions and refine processing parameters.
Expanding Resource Potential and Next Steps
In addition to metallurgical advances, geological mapping has expanded the interpreted surface area of the Kary Zone from approximately 3.5 to 8.2 square kilometres, suggesting a larger near-surface resource than previously understood. Follow-up drilling and heritage surveys are underway to confirm this extension.
Further bottle roll tests on the western Templeton Zone and column leach tests on weathered Kary Zone ores are scheduled to begin shortly. These studies will provide more definitive data to support early-stage mine scoping and economic modelling. Red Metal is also investigating dynamic acid management strategies during heap leaching to maximise rare earth recovery while minimising costs.
Overall, the Sybella project continues to demonstrate characteristics of a potentially large-scale, low-cost rare earth operation, with processing innovations that could set it apart in the global rare earths market.
Bottom Line?
Red Metal’s Sybella project advances towards economic viability with promising low-cost processing and expanding resource potential, but upcoming column leach results will be critical to confirm these gains.
Questions in the middle?
- Will the upcoming column leach tests confirm the bottle roll test optimisations under more realistic conditions?
- How will spatial variability in ore response, especially in the SMS12 composite, affect overall resource processing?
- What are the projected capital and operating cost savings from reduced acid consumption and impurity removal in heap leach processing?
