Alvo Minerals Limited (ASX: ALV)(“Alvo” or the “Company”) is pleased to announce results from initial metallurgical testwork undertaken on auger drill samples from the Bluebush Ionic Clay Rare Earth Project (“Bluebush” or “The Project”). Bluebush is located on the northern half of the Serra Dourada granite, the same host rock of the Serra Verde Ionic Clay REE deposit (“Serra Verde”), believed to be the only ionic clay project currently being commissioned outside of China.
HIGHLIGHTS
- Initial metallurgical testwork on auger samples shows excellent extractions of rare earth elements (REE) using industry standard ammonium sulphate solution (AMSUL) .
- High-value magnet rare earths (MRE) recovery rates using weakly acidic (pH 4) AMSUL at ambient temperatures achieved the following extractions (after 30 minutes):
- Neodymium (Nd): up to 89% averaging 60%.
- Praseodymium (Pr): up to 86%, averaging 57%.
- Dysprosium (Dy): up to 53%, averaging 37%.
- Terbium (Tb): up to 69%, averaging 48%.
- Total MRE (Nd,Pr,Dy +Tb): up to 83%, averaging 56%.
- The results show that excellent REE desorption was achieved across samples taken from the Boa Vista and Sao Bento prospects using industry standard conditions and crucially confirms that the Bluebush Project is an ionic (adsorption) clay REE project.
- Metallurgical samples will be tested from current diamond drilling to target high-grade zones and further optimise recovery ratios.
- Diamond drilling continues at the highest grade MRE zones, to test the depth profile and extent of the ionic clay. Auger results include results up to 3m @ 3,415ppm TREO at EOH.
- Truck mounted auger drilling continues to test extents of the mineralisation (open in all directions) and some handheld auger is also underway to test for new regional prospects.
The results confirm the status of Bluebush as an ionic clay (adsorption) REE project, important due to the simpler potential mining and processing costs with associated lower capital and operating costs than other hard rock or simple clay hosted REE prospects.
Rob Smakman, Alvo’s Managing Director commented on this critical step:
“This is a significant step forward for Bluebush with the confirmation of Ionic clay adsorption hosted mineralisation at both Boa Vista and Sao Bento. The results are outstanding for initial metallurgical testwork with individual samples of MRE’s recovering up to 83%.
We have said from when we acquired this exciting project, there were three things we wanted to clearly demonstrate during the due diligence period: Scale, Grade, and Ionic Clay (Adsorption) Mineralisation. Our results released to date have demonstrated high grades of TREO and MREO near surface and over broad areas at both Boa Vista and Sao Bento prospects, covering the potential size and grade questions. The final, and possibly the most important factor, was establishing the presence of ionic clay adsorption hosted mineralisation. The testwork released today shows this.
With samples from over 130 auger holes still in the lab, ongoing diamond drilling, regional exploration through handheld auger drilling and the initiation of the Loupe geophysical surveys, we expect there will be plenty to report leading into the end of CY2023 from the Bluebush Ionic REE Project.”
Bluebush Metallurgical Results
The results reported here are from auger drilling at the Boa Vista and Sao Bento prospects, part of the larger Bluebush Project (see Figure 1). Samples were collected at 1-2m intervals and sent to the SGS GEOSOL lab in Goiania and Belo Horizonte, Brazil.
Standard sample preparation at the lab (see Appendix 1) was undertaken before a sample was screened to - 4mm. The ionic adsorption clay-hosted rare earth element leach test used a diluted solution of 0.5 molar ammonium sulphate at room temperature and a pH 4 for 30 minutes. Recoveries above 30% are considered by Alvo to confirm the ionic nature of the mineralisation.
Future metallurgical investigations will be designed using the follow-up auger drilling and diamond drilling samples to improve the overall MREO recoveries and develop a more complete understanding of the nature of the clays. It is important to note that the results of the AMSUL desorption stage are un-optimised, and further work to seek to further improve REE extractions is being planned.
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