Heavy Rare Earths (ASX:HRE) has delivered a 2-fold increase and up to 91.3% extraction of magnet rare earths through metallurgical testwork at its Cowalinya Project in Western Australia.
Perth-based Strategic Metallurgy subjected rare earth fine fractions from 13 previously tested composites to diagnostic leaching tests to determine the efficiency with which the rare earths are brought into the solution, using weak hydrochloric acid, sulphuric acid, and ammonium sulphate.
In all cases, the tests using hydrochloric acid delivered ‘superior’ rare earth solubility and acid consumption results, with 8 of the 13 composites demonstrating a ‘high’ leachability of over 75% of the magnetic rare earths praseodymium, neodymium, terbium, and dysprosium.
This testing also demonstrated a ‘low’ acid consumption of less than 40kg per tonne of fines, with an average of 82.9%, and 18.1kg respectively. Considering the rare earths-containing fines fraction accounts for an average of 42.1% of the saprolite feed mass, hydrochloric acid consumption is expected to average 7.6kg per tonne of saprolite feed.
Heavy Rare Earths reports these results justify an accelerated metallurgical testwork program over the coming months which will focus on optimising leach conditions, extending the diagnostic program, and starting a bench-scale program to develop a flowsheet to a Mixed Rare Earth Carbonatite (MREC) product.
Subject to the outcome of the program, the company plans to make MREC samples available to refiners in Europe, Asia, the US, and Australia to determine marketability.
Heavy Rare Earths expects to report new mineral resources and a maiden exploration target for Cowalinya in Q3 2024, while Strategic Metallurgy expects to complete the accelerated testwork program in Q4 2023.
Heavy Rare Earths’ shares closed 10% higher at $0.11 on Wednesday afternoon following this news.
Commenting on the results, Heavy Rare Earths Executive Director Richard Brescianini says: “We are making excellent progress on our metallurgical program to establish an optimal process route for the rare earth resources at Cowalinya.
Our earlier reported sizing work gave us confidence that simple, low-cost screening is capable of delivering a 2-fold increase in rare earth concentration for leaching. More recent diagnostic leaching of this upgraded material has yielded a number of highly promising magnet rare earth extractions with low acid consumption, both of which are central to technical and commercial viability.
“our forward program now has its sights firmly set on producing samples of a Mixed Rare Earth Carbonatite”
Whilst we acknowledge some variability in these results and the need to further optimise leach performance, our forward program now has its sights firmly set on producing samples of a Mixed Rare Earth Carbonatite, the first possible entry point by HRE into the rare earth supply chain.”
Initial sizing testwork in 2022 conducted on the 13 composites from across Cowalinya demonstrated an average of 78.5% of the rare earths was hosted in the fine fraction, which comprises 37.2% of the bulk saprolite feed mass.
Heavy Rare Earths is an Australian rare earths explorer and developer focused on its ‘key’ Cowalinya Project near Norseman in Western Australia. Cowalinya is a clay-hosted rare earth project with an inferred resource of 28 million tonnes @ 625 parts per million (ppm) Total Rare Earth Oxide (TREO).
The company had $2.605 million cash at hand on 31 March 2023, according to its latest quarterly report published on 27 April 2023.
Write to Harry Mulholland at Mining.com.au
Images: Heavy Rare Earths Ltd