Brazilian Critical Minerals Ltd Achieves Excellent Column Leach Results at Ema Project

Overview of Test Results

The recent column leach tests at the Ema Rare Earths Project have shown a 63% recovery rate for key magnet rare earth oxides (Nd/Pr/Dy/Tb) after just 18 days of leaching, followed by washing to recover residual material using magnesium sulfate. These results were calculated as an average of two extraction methodologies, suggesting a simpler and lower-risk process flow sheet from mine to final product compared to traditional methods.

The tests were conducted by Australia's Nuclear Science and Technology Organisation (ANSTO) using a 50 kg master composite collected from 12 holes and 62 samples. The results indicate the possibility of constructing a low CAPEX rare earth heap leach operation at Ema, which could significantly reduce the number of processing steps and associated risks.

Heap Leach Amenability

Column leach liquor results using magnesium sulfate returned recovery values of 42% for Nd, 41% for Pr, 30% for Dy, and 34% for Tb after 4 days. These values increased to 52%, 51%, 36%, and 41% respectively after 6 days, and further to 57%, 55%, 40%, and 45% after 11 days. The final recovery after 18 days of leaching followed by washing recorded a combined recovery of 63% for MREO (Nd/Pr/Dy/Tb).

The ore agglomerated readily in the test liquor without the need for additional acid, and the agglomerated ore remained competent in the column test. The permeability of the column bed was good, with minimal bed slump of 1% calculated. Test conditions involved REE desorption utilizing 0.5 M magnesium sulfate or 0.3 M ammonium sulfate at ambient temperature and pH of 4.5. Acid consumption was calculated to be less than 1 kg/t.

Future Plans

Following these promising results, Brazilian Critical Minerals Ltd intends to fully explore the possibilities of in-situ leaching of the Ema mineralization, which would involve even fewer processing steps from mine to final product than heap leaching. This approach could further reduce CAPEX and OPEX costs, making the Ema project one of the greenest and environmentally friendliest mines ever constructed.

Andrew Reid, Managing Director of BCM, commented on the results, stating, 'These results are quite stunning in their simplicity. To be able to desorb the rare earths so quickly at a high rate of recovery is quite remarkable. The physical and chemical characteristics of the mineralization at Ema have now been thoroughly tested, giving similar results for both slurry (tank leaching) and now heap leaching.'

The company is confident that high recoveries can be achieved with in-situ leaching, with the only unknown element being clay permeability. Field and lab work to demonstrate the permeability of the Ema mineralization to in-situ leaching is now being planned.