Magnesium Sulphate Migration Lowers pH to Target Rare Earth Leaching at Ema
Brazilian Critical Minerals has achieved a significant milestone in its Ema project by successfully demonstrating magnesium sulphate migration and pH reduction in field trials, validating its in-situ recovery method for rare earth elements.
- Magnesium sulphate tracer detected in multiple extraction holes
- pH levels lowered to below 4.0, enabling rare earth leaching
- Permeability through clay zones exceeds laboratory estimates
- Impermeable basement rock confirmed, supporting solution retention
- Extracted solutions sent for laboratory analysis to confirm rare earth content
Field Trial Breakthrough at Ema Project
Brazilian Critical Minerals Ltd (ASX – BCM) has reported a pivotal technical achievement at its Ema rare earth elements (REE) project in Brazil. The company’s recent field trials successfully tracked the migration of magnesium sulphate, a tracer reagent, from injection points to extraction wells. This movement confirms the feasibility of their in-situ recovery (ISR) process, a low-impact extraction method that could revolutionize how rare earths are mined from ionic adsorbed clay deposits.
Crucially, the pH of the solution in extraction holes dropped to or below 4.0, the threshold necessary to leach rare earth elements into solution. This milestone indicates that the chemical environment required for efficient ISR has been achieved in real-world conditions, not just in laboratory settings.
Permeability and Geological Integrity Confirmed
The trials also revealed that solution flow rates through the clay horizon exceeded previous laboratory estimates, suggesting better-than-expected permeability. Monitoring wells showed a steady rise in solution levels, implying that the underlying basement rock is largely impermeable. This impermeability is vital as it prevents solution loss, ensuring that the leaching process remains contained within the mineralized zone.
Such geological conditions are essential for ISR success, as they allow the injected solution to percolate through the target clay layers effectively while minimizing environmental risks associated with fluid migration beyond the deposit.
Next Steps and Industry Implications
Extracted solutions containing potentially leached rare earths are currently en route to laboratories for detailed analysis. These results will be critical in confirming the economic viability of the ISR method at Ema. The field trial was independently supervised by WSP Brazil, adding credibility to the findings and reinforcing confidence in the project’s technical approach.
Managing Director Andrew Reid emphasized the significance of these developments, describing them as a major de-risking milestone that advances the project closer to commercial production. The company plans to incorporate this data into hydrogeological models for its upcoming bankable feasibility study and environmental permitting processes, which are overseen by Brazilian regulatory body CERN.
With a defined mineral resource of 943 million tonnes at promising grades and metallurgical recoveries averaging 68%, BCM’s progress with ISR technology could position the Ema project as a leading source of rare earth elements with a comparatively low environmental footprint.
Bottom Line?
BCM’s ISR field trial success marks a critical step toward unlocking sustainable rare earth production at Ema, with assay results and feasibility studies next to watch closely.
Questions in the middle?
- Will laboratory assays confirm economically viable rare earth concentrations in extracted solutions?
- How will ISR scalability impact the timeline and cost of commercial production at Ema?
- What environmental safeguards will be implemented during full-scale ISR operations?
