Mount Ridley Hits 91.8% Scandium Recovery at Half Reagent Dose
Mount Ridley Mines (ASX: MRD) achieved 91.8% scandium recovery in Selectro Test 3 using half the reagent dose, with HREE ~84% and LREE ~77% at Grass Patch.
Mount Ridley Mines (ASX: MRD) achieved its strongest scandium and rare earth element (REE) recoveries from the Selectro process, with Test 3 delivering 91.8% scandium recovery at half the reagent dose used in earlier tests.
Heavy REE recoveries averaged about 84%, with peaks at 86%. Light REE averages reached about 77%, with highs of 81%. The work used the same unbeneficiated Grass Patch composite as previous testing, without process optimisation.
The halved reagent dose in Test 3 lifted scandium recovery from 80% in Test 2 and increased average HREE recovery from 78.5% to 84%. Gallium recovery fell to about 41.5% from 55.8%, showing different responses among elements.
Mount Ridley attributed the improvement to molecular tuning of the Selectro leaching chemistry, which allows the composition of the leaching molecule to be adjusted towards targeted metals.
Managing director Allister Caird said the results were "particularly encouraging" given they were achieved on unbeneficiated material at an early stage of the test work program. "Combined with the scale of the existing mineral resources at Grass Patch, they give us confidence as we advance Selectro into flotation concentrate and bulk sample testing," he said.
The metallurgical test work was done by Nagrom at its Kelmscott laboratory using a 16.8kg homogenised composite from five historical Grass Patch diamond drill holes. Comparative testing used representative aliquots of about 90 grams, with Selectro and hydrochloric acid baseline tests each conducted over a 24-hour leach period at atmospheric pressure.
The Selectro tests achieved maximum recoveries in under four hours. The company has not yet established the lower limit of reagent concentration that can be used.
Mount Ridley considers the latest work a foundation for further optimisation because it was completed on unbeneficiated material. The balance between scandium, HREE, LREE, and gallium recovery still needs refinement.
Flotation test work on Grass Patch material is underway and will determine the beneficiation approach used before Selectro moves into bulk sample testing. Earlier mineralogical work identified the REE as predominantly hosted in discrete phosphate minerals, including xenotime and crandallite group phosphates.
Mount Ridley plans to incorporate the Test 3 results into updated process economics and scoping assumptions. Further work will test whether lower reagent concentrations can retain or improve targeted recoveries.
Bulk sample testing will then assess both the reduced-reagent approach demonstrated in Test 3 and flotation-beneficiated feed. The company also plans to validate the Selectro process on third-party material.
Drafted by a large language model from the source reporting linked above, then screened by automated publishing checks. It is not read by a journalist before publication. Some articles cite our Alpha Score. Verify prices and figures against the original source. Educational coverage, not personalized advice.