ASX-listed Northern Minerals has progressed its potentially game changing ore sorting initiative with the successful testing of the sorter system at its Browns Range rare earths pilot operation in the north of WA. The company is now producing sorted material and converting this to a 30 percent total rare earth oxide concentrate at its Browns Range pilot beneficiation plant in the north of WA. Processing of the ore sorted material has resulted in remarkably better recoveries in the magnetic separation and flotation plants according to management.
Northern Minerals commenced the production of heavy rare earth carbonate in late 2018 as part of pilot assessment of the economic and technical feasibility of a larger scale development at its flagship Browns Range project.
A two-metre wide Steinert sorter which uses X-ray transmission and laser detectors to separate the rare earth mineralisation from the waste ore was chosen for the test work. The ore sorter system was constructed during 2020 and 2021 and commissioned in June 2021. The sorter has been run over two test campaigns which included 41 test runs processing 5,300
tonnes of ore from stockpiles largely from ore from the company’s Wolverine deposit.
Additionally, five test runs were performed on 285 tonnes of Banshee ore bulk sampled from a surface costean.
Significantly, the tests have confirmed simultaneous sorting of two size fractions is possible on the sorter.
The sortable fraction of Wolverine ore can be successfully sorted to give an impressive 90 per cent total rare earth oxide recovery. When combined with non-sortable fines this achieves a whopping 45 per cent grade increase to the mill and over 95 per cent total rare earth oxide recovery when feeding a 0.9 per cent total rare earth oxide ore.
Initial sorting tests of the Banshee deposit ore have indicated the highly oxidised surface material contains a large fines fraction and the grade of the sortable fraction can be doubled, recovering more than 60 per cent total rare earth oxide in 25 per cent of the mass. The company is extracting an additional bulk sample from deeper in the costean and three diamond drill holes are planned for further test work.
Northern Minerals Chief Executive Officer, Mark Tory, said: “The construction, commissioning and testing of the ore sorter circuit marks another milestone in the development of the Browns Range Project. The positive bulk sample tests confirm the effectiveness of the ore sorting circuit on the Wolverine ore to significantly increase the head grade to the mill which is expected to result in higher production rates and lower operating costs for a full-scale operation at Browns Range”
Tory added “It’s also pleasing to see the initial ore sorting tests the Banshee ore showing promise which, if shown to be effective in future tests, has potential to significantly increase the Browns Range Mineral
Resource Estimate.”
The ore sorter system is now being run to produce feed for the beneficiation plant and so far, 4,479 tons of Wolverine ore were processed through the circuit to the end of August.
Importantly, processing of the ore sorted material has resulted in remarkably better recoveries in the magnetic separation and flotation plants compared to feeding unsorted ore.
A bulk sample of 50 tonnes of 30 per cent total rare earth oxide concentrate has been produced for test work by other processing plants identified with likely future capability and capacity to process the heavy rare earth xenotime concentrate produced at Browns Range.
The company says being able to test and operate the ore sorting circuit in conjunction with the pilot beneficiation plant is providing extremely valuable data which will feed into its feasibility study for a potential commercial scale heavy rare earth operation at Browns Range.
Northern’s wholly owned Browns Range project in WA’s East Kimberley region has several deposits and prospects containing high value dysprosium and other heavy rare earth elements hosted in the mineral xenotime. Demand for heavy rare earth elements, in particular dysprosium and terbium, continues to be driven by strong growth in the high-performance dysprosium neodymium-iron-boron magnet sector. Applications for the permanent magnets are numerous and include the renewable energy, transport electrification, military, and high-tech industries.
Northern Minerals says it is looking to finalise the feasibility study on the potential development of a full-scale beneficiation plant at Browns Range around the middle of next year.
Through the development of its flagship Browns Range project, Northern has its sights set on building its West Australian operation into the most significant world producer of dysprosium outside of China, which currently supplies 98 per cent of the global market.
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By Matt Birney
