Cyclosizer pumps up Goldfields rare earths for Larvotto

Larvotto Resources says new testwork shows it can simply and efficiently upgrade rare earths samples from its Eyre multi-element project in Western Australia’s Goldfields region by using a hydrometallurgical cyclosizer.

Previous metallurgical testing on air-core (AC) drill samples from the company’s Merivale South prospect revealed that screening to minus-25 micron more than doubled the sample grade.

However, recently completed testwork by Independent Metallurgical Operations (IMO) that focused on the upgraded fraction revealed further upgrading is possible using a simple hydrometallurgical cyclosizer. A cyclosizer creates a vortex effect to separate particles.

The sample analysed during testwork had an average rare earth oxides (REO) grade of more than 5000 parts per million total rare earth oxides (TREO). In April, AC drilling at Merivale South returned impressive TREO results of up to 1.26 per cent, or 12,611ppm, including 3787ppm magnetic rare earth oxides (MREO). 

Larvotto says a cyclosizer can be used for the rapid and accurate determination of particle size distribution within the sub-sieve range that efficiently creates accurately-sized sample fractions. The recent cyclosizer testwork divided the minus-25 micron sample into six further size ranges and 82 per cent of the rare earths reported were in the finest fraction, which was analysed by a scanning electron microscope.

Results show the majority of the mineralisation containing rare earths was contained in fluorcarbonate minerals from the bastnäsite group, which is one of the biggest sources of cerium and other rare earths. Further analysis of the individual minerals within the finest fraction revealed liberation rates of more than 91 per cent of the bastnäsite, making it easily accessible for leaching.

Management says now that the minerals containing the majority of the REO have been identified and can be easily upgraded, studies will begin on the best method of extracting the rare earths from the mineralisation. It will include testwork to determine leach amenability and reagent consumption to determine if a viable process path exists, with testing to kick off this month.

Larvotto Resources managing director Ron Heeks said: “This recent round of testwork has added significantly to our knowledge of the deposit and its mineralogy. A highlight is the simple and efficient upgrading of REO by hydrometallurgical processes. A good understanding of the exact mineralogy gained from TIMA studies will now allow us to target extractive metallurgical processes in the next phase of testwork. The significant reduction in calcite, which is a high acid consuming mineral, during upgrading is also extremely positive.”

Heeks said the company was anxious to see results from the next phase of extractive testwork that is due to begin this month.

Larvotto holds a significant patch of ground in WA’s renowned Goldfields region, as the Eyre project covers 580 square kilometres about 30km east of Norseman and is considered prospective for rare earths, gold, lithium, base metals and platinum group elements (PGE).

A recent 2383m reverse-circulation (RC) drill campaign identified a significant nickel-copper anomalism at the company’s Mt Norcott prospect, with an ultramafic nickel anomaly intersected on the western side of Merivale. Assay highlights show a 100m section at 675ppm nickel from surface, including 4m grading 0.178 per cent nickel and 913ppm copper.

Thick pegmatites were also drilled at Merivale with anomalous results for lithium, while multiple pegmatite swarms have been located throughout the Eyre project.

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