St George Mining’s initial beneficiation testwork at its Araxá Project in Brazil has delivered high-grade niobium concentrates and a promising rare earth concentrate, validating its dual commodity approach and underpinning next-stage pilot plant plans.
- Niobium flotation testwork yields up to 40.2% Nb2O5 grade with 54.3% recovery
- Rare earth concentrate graded 15.7% TREO recovered from niobium flotation tailings
- Testwork sample of 5 tonnes reflects near-surface saprolite mineralisation for early mining
- Pilot plant studies scheduled for Q3 and Q4 2026 to optimise processing
- Resource hosts significant magnet and heavy rare earth oxides alongside niobium
High-Grade Niobium Concentrates Confirmed in Early Flotation Tests
St George Mining Limited (ASX:SGQ) has reported encouraging initial metallurgical results from its Araxá Niobium and Rare Earth Project in Brazil, with flotation testwork producing niobium concentrates grading around 40% Nb2O5 and recoveries up to 54.3%. These figures align well with industry standards for Araxá-style pyrochlore mineralisation, where typical flotation grades range between 40% and 50% Nb2O5 and recoveries between 40% and 60%.
The testwork was conducted on a substantial five-tonne bulk sample of near-surface saprolite material, representing the kind of ore likely to be mined in the early years of production. This provides a robust foundation for subsequent development studies. The flotation was performed in open circuit mode, with locked cycle and recycle flotation tests now underway to optimise recovery and concentrate grades further.
Rare Earth Concentrate Emerges from Niobium Flotation Tailings
Beyond niobium, the flotation tailings from the niobium circuit have yielded a rare earth concentrate grading 15.7% total rare earth oxides (TREO), a 1.6-fold upgrade from the 9.8% TREO grade in the original sample. This rare earth concentrate was obtained via reverse flotation of silica minerals, a technique commonly used in iron ore processing.
Approximately 82% of the rare earths were recovered overall, with 59.7% reporting to the niobium flotation concentrate and 33.2% to the silica flotation tails. This dual commodity potential is a distinctive feature of the Araxá Project, which hosts a large, high-grade resource rich in magnet rare earth oxides (Nd-Pr) and meaningful heavy rare earth oxides (HREO) such as yttrium and dysprosium.
Metallurgical Program Accelerates with Pilot Plant Studies
Building on these promising early results, St George is advancing its metallurgical program with locked-cycle and recycle flotation testwork at multiple international laboratories, including SGS Lakefield in Canada. A one-month pilot plant study by CIT-SENAI in Brazil is planned for July 2026, followed by commissioning of St George's large-scale pilot plant at CEFET-MG in Araxá by late Q4 2026. This facility aims to process up to 300kg/hour and produce a range of products including niobium concentrates, ferroniobium, and various rare earth products.
The company has assembled a technical team with deep experience in Brazilian niobium and rare earth processing, including veterans from CBMM, the world’s largest niobium producer, and rare earth operations in Brazil and Australia. This expertise will be critical in refining flotation performance and downstream refining pathways, particularly to manage impurities such as lead oxide associated with the pyrochlore mineralisation.
Resource Scale and Composition Support Strategic Positioning
The Araxá Project's JORC-compliant Mineral Resource Estimate (MRE) defines a substantial 70.91 million tonnes grading 4.06% TREO and 0.62% Nb2O5 at a 2% TREO cut-off, with an additional 24.56 million tonnes at lower TREO grades but significant niobium content. The resource is notable for its rare earth element basket, with magnet rare earth oxides (neodymium and praseodymium) comprising approximately 20% of TREO and heavy rare earth oxides contributing about 2.55%, including yttrium which accounts for 42% of the heavy suite.
Such a composition places Araxá among a select group of global deposits offering both high-grade niobium and rare earths, positioning St George to potentially capitalise on multiple critical metal markets. The project’s proximity to CBMM’s established operations and supportive infrastructure in Minas Gerais further enhances its development prospects.
Regulatory and Operational Considerations Remain in Focus
While the metallurgical results provide a strong technical foundation, St George’s path to production depends on progressing tenement renewals and mining approvals in Brazil. Some project areas are subject to environmental protections and require government permits for mining activities, adding layers of regulatory complexity. Royalties payable on net smelter returns also vary depending on project economics.
With pilot plant operations slated for the second half of 2026 and ongoing optimisation testwork, the company’s next milestones will be critical in translating laboratory success into commercial viability. The dual commodity nature of the Araxá Project offers a compelling narrative in the critical metals sector, but refining processing flowsheets and navigating regulatory hurdles will be key challenges ahead.
Bottom Line?
St George’s initial metallurgical success at Araxá validates its dual niobium-rare earth strategy, but the transition from testwork to commercial production hinges on pilot plant outcomes and regulatory progress.
Questions in the middle?
- How will locked-cycle and recycle flotation tests improve niobium and rare earth recoveries?
- What refining pathways will St George pursue to manage impurities like lead oxide in niobium concentrates?
- How might regulatory approvals and tenement renewals impact the project timeline and development costs?