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Heavy rare earths hits continue at ABx Group Tasmanian project

Rare-earths from ABx Group’s Deep Leads-Rubble Mound project in Tasmania. Credit: File

ABx Group (ASX: ABX) latest assay results have further expanded the rare earths zone at its Deep Leads-Rubble Mound project in northern Tasmania, showing mineralisation enriched in the valuable heavy rare earths, dysprosium and terbium.

The company says the results prove the site west of Launceston retains the highest proportion of the two elements of any clay-hosted rare earths resource in Australia.

ABx has received high-grade rare earths assay results from 19 more holes flowing from its 97-hole drill campaign at the Rubble Mound high-grade rare earth zone. It says results for a total of 85 holes have been received, with 12 holes remaining.

The latest bunch of assays showed several one-metre intersections of total rare earths oxides exceeding 1500 parts per million with results including 2261ppm and 1872ppm. Promisingly, assays highlighted  six one-metre intersections of the heavy rare earths that include dysprosium and terbium, to be greater than 4.5 per cent of total rare earths, including 5.8 per cent and 5.2 per cent results.

The company says the dysprosium-terbium levels average about 4.5 per cent of the total rare earth oxides. It says ratios above 5 per cent are rare anywhere in the world, making the resource a valuable source of heavy rare earths. An added benefit to the resource is the low levels of thorium and uranium.

ABx’s distinctively high proportion of dysprosium and terbium with high extraction rates under relatively neutral conditions is rare. We look forward to announcing a resource update soon, which will include Wind Break for the first time but will still only cover a fraction of ABx’s northern Tasmanian rare earth exploration target area of over 100 square kilometres.
ABx Group managing director and chief executive officer Mark Cooksey

Management says the zone is proving to be significantly larger than estimated in its 52 million tonne rare earth resource that was reported last year. The results also extend the high-grade rare earth mineralisation south-west towards its Alluvial Flats zone that has some especially thick mineralisation, with previous results up to 3865ppm.

Encouragingly, it was the first time ABx had aimed drilling specifically at rare earths within the high-grade Rubble Mound zone that was previously only targeted for bauxite in shallow zones.

The company has found there is typically a low-grade, rare earths-depleted surface layer of 2m to 5m that overlays an enriched layer of about 4m to 17m in thickness.

Management also says that once the outstanding assays have been received, expected to be in April, a resource update will be undertaken that will include its Wind Break deposit for the first time. A recent 30-hole drilling campaign at Wind Break produced a series of 1m intersections grading higher than 2000 ppm total rare earths and elevated levels of dysprosium-terbium in line with the levels encountered across the full resource.

The company revealed a mineral resource estimate for its Deep Leads-Rubble mound project in November last year, using a statistical “block-modelling” method that is widely employed within the industry. It provides the benefit of mapping the distribution of high-grade sections within the deposit.

The resource contained 52 million tonnes at 817ppm total rare earths and 26 per cent magnet rare earth oxides. Dysprosium-terbium made up 4.4 per cent of the total rare earths.

Australia’s Nuclear Science and Technology organisation (ANSTO),  Australia’s leading scientific organisation for the testing of rare earths last year conducted metallurgical testing on the clay deposits found at the project site.

It found the samples tested to be of the ionic-clay variety, with the clay-rich samples producing the highest extraction rates up to 83 per cent. 

Ionic clay rare earth projects have many advantages over their hard-rock counterparts. Despite lower grades and lower recoveries, the extraction of ionic-adsorption clays is levels cheaper from an operational and capital perspective.

Benefits include mineralisation occurring at surface, minimal stripping, clay-hosted soft material requiring no blasting, no crushing and milling and a simple one-step leaching process. There is also no requirement for a tailings dam, low levels of uranium and thorium and no radioactive tailings.

Due to the attractive levels of both magnet and heavy rare earths contained within the resource, ABx’s strategy is to produce a mixed rare earths carbonate that it can sell to existing refineries to increase their production. The fact that the carbonate is expected to be high in the valuable heavy rare earths and low in radioactive elements, is almost certain to be attractive to many prospective customers.

The company says its existing focus is on creating an ionic adsorption clay rare-earths project in northern Tasmania, in addition to establishing a plant to produce hydrogen fluoride and aluminium fluoride from recycled industrial waste, via its subsidiary company Alcore, which it owns an 83 per cent stake in.

With one of Australia’s few truly ionic-clay rare earths deposits on its hands, if Abx can continue to build the resource into an economic proposition, it may find industry players knocking on its door instead of the door of its Chinese competitors and wouldn’t that be ironic.

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