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Voltaic Strategic Resources Limited (ASX:VSR) is pleased to advise that step one (beneficiation) of the two-step sighter metallurgical test program is complete for the REE-enriched clays identified at the Neo prospect, Paddy’s Well Project, and the results are very encouraging.
Highlights
- Step 1 beneficiation tests show rare earth element (REE) enriched clays at the Neo prospect are highly amenable to upstream beneficiation.
- By selectively removing ‘coarse’ (large) particles from the Neo clay samples, several significant benefits have been demonstrated (see Figures 3 - 6):
- Significant boost in REE grades - up to 67% increase in valuable MREO1 & 66% in TREO;
- Substantial reduction in waste / ‘gangue’, implying likely reduced reagent consumption & equipment requirements for a full-scale REE process plant.
- Encouraging indicators for REE ionic adsorption deposit (IAD) potential (alumina-rich, low iron, low calcium, and halloysite).
- Step 2 leach metallurgical testing now underway to characterise the REE species present.
Voltaic Chief Executive Officer Michael Walshe said the ‘size by assay’ analysis work has demonstrated that the majority of REEs within the clay system at Neo are hosted in the ultrafine (<20µm) size fraction and are highly amendable to upstream beneficiation.
“This presents Voltaic with an opportunity to significantly upgrade REE grade, reduce the quantity of material processed, reduce deleterious elements, and substantially decrease reagent consumption and equipment requirements for full-scale operation,” Mr Walshe said.
“Up to 94% of the valuable magnetic (Nd, Pr, Dy, Tb) REE mass can be recovered in the -20µm size fraction (particles <20µm), whilst removing ~40% of the total mass as waste (see Fig. 4 & 6).
“This represents is a major step forward in proving the economic viability of a REE project at Neo.
“We are eagerly awaiting step two leaching testwork results, which we should have in approximately four weeks,” he said.
Figure 1. Location of the Neo prospect area, Paddys Well project.
There are several encouraging indicators for economic potential at Neo:
- Alumina-rich, low iron kaolinitic clay confirmed with Al2O3 grades up to 36% (by mass) & very high Al2O3 / Fe2O3 ratio (favourable for ionic adsorption deposit potential) (see Table 8).
- Low CaO content within clay (maximum 0.4% by mass) - potentially favourable for reduced acid consumption during leaching stage (see Table 8).
- Halloysite previously identified (favourable for ionic adsorption potential)2.
Favourable IAD test results are critical to the economic viability of REE clay deposits. The key evaluation metric is the recovery of the magnetic REEs under ‘ionic’ test conditions whereby ammonium sulphate is employed as the ion-exchange medium, and the pH is kept mildly acidic (seeFig.2). If very low pH (highly acidic) conditions are required, then the material will likely contain more refractory forms of REEs as opposed to ionically adsorbed species, and unwanted impurity elements such as Al and Fe may also solubilise.
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