Rimfire Resources ASX Announcement

Metallurgical testwork undertaken on Melrose Nickel Cobalt Scandium Prospect

Prior to commencing the testwork program, IMO’s senior metallurgist Dr Andrew Dowling completed a literature review which emphasised that the High-Pressure Acid Leach (HPAL) process is the dominant commercial method used to process nickel laterite- hosted mineralisation, such as that found at Melrose.

The literature review found that instances of Atmospheric Leaching (AL) and Heap Leaching (HL) of lateritic material are extremely rare. However, these two forms of leaching testwork are usually performed prior to HPAL testwork, as they are more economically favourable at full scale (lower CAPEX/OPEX) if metal recoveries are close to the higher recoveries that may be achieved by the HPAL technique.

Consequently, the AL option was undertaken with the aim of obtaining the best metal recoveries and to provide a solid foundation for further studies into commercialising the extraction of mineralised material from Melrose and the surrounding Rimfire critical prospects.

All atmospheric leach tests were performed as whole-of ore leaches and conditions were formulated as reductive acid leach tests. Results showed recoveries of up to 40% scandium, 90% cobalt and 58% nickel at atmospheric pressures.

Rimfire’s MD/CEO David Hutton: “The results of the first pass sighter leach test work are highly encouraging and pave the way for ongoing metallurgical and geological studies at Melrose. […] we believe that further testwork recommended by our metallurgical consultants will meaningfully increase metal recoveries, especially for scandium.”

Scandium’s importance is shown by its inclusion in both Australia’s 2023 Critical Minerals List and the United States Geological Survey’s 2022 List of 50 minerals commodities critical to the economy and national security. Incorporation of scandium in materials has environmental benefits, particularly in decarbonisation of energy.

Encouraged by our testwork results, Rimfire Pacific Resources have decided to undertake an RC and DD drilling program to underpin the estimate of a maiden Mineral Resource Estimate in accordance with the 2012 JORC Code.

IMO and Metallurgy are looking forward to undertaking further leaching tests with a particular emphasis on maximising scandium recovery, as well as optimising energy requirements and reagent consumption.

If you are looking to find out more about your critical minerals’ project, reach out to us today. Our #metallurgical experts are looking forward to assisting you with your project:
imo@indmetops.com.au or +61 (0) 8 9254 6900