American Rare Earths Ltd (ASX:ARR)’s latest metallurgical test work from its La Paz rare earths deposit continues to prove the potential of the project.
The test work has resulted in the design of a simplified concentrator flow sheet for mine planning and has confirmed that the ore responds positively to conventional processing.
Reduced operating and capital costs
The company commissioned Wood Australia Pty Ltd to manage and interpret the test work program on supplied composites of split diamond drill core produced in a drilling program conducted in early 2021 at the Paz Rare Earths Project in Arizona USA.
The work follows on from test work conducted on drill chip samples taken by the Saskatchewan Research Council (SRC) in Canada during 2020 under Wood’s direction, which provided preliminary guidance on processing routes to treat this ore.
The new results support this previous test work, pointing to opportunities to reduce operating and capital costs.
Test work
Cores were subjected to the following test work elements:
- mineralogical characterisation;
- comminution;
- low-intensity magnetic separation (LIMS);
- wet high-intensity magnetic separation (WHIMS);
- flotation – sighter rougher tests (both direct allanite flotation and reverse silica flotation); and
- leaching – Watts & Fisher’s proprietary modified phosphoric acid leaching process, testing WHIMS concentrate.
The company believes capital and operating costs will be reduced with 75% of the gangue material removed through magnetic separation.
Results also confirm very low thorium and uranium penalty elements.
The conceptual flowsheet developed maximises the recovery of rare earth metals, particularly high-value magnet metals neodymium and praseodymium, which the company has been targeting.
Valuable insight was gained into accelerating the technical development of the Halleck Creek project, given its similarities to La Paz.
Flow sheet design
As part of the latest metallurgical testing campaign, the company requested Wood Australia Pty Ltd (Wood) use the results to develop a conceptual flowsheet for the La Paz concentrator.
The company also sought guidance for its annual processing capacity based on a single processing line using the most capital-intensive equipment, which assists with mine planning.
Work in the pipeline will build upon these results to refine the processes developed throughout the flowsheet to maximise the recovery of rare earth metals, particularly high-value magnet metals neodymium and praseodymium, which are the focus at La Paz.
"These latest metallurgical results are extremely encouraging and continue to advance the La Paz Project in the right direction in its development,” CEO and managing director Chris Gibbs said.
“We acknowledge the great work industry leaders Wood Australia, Nagrom and Watts & Fisher have been conducting on our behalf.
'Game-changer'
“With its high levels of rare earth metals extraction and rapid dissolution times, Watts and Fisher's leaching technology could be a game-changer in developing La Paz and Halleck Creek, given the projects share similar mineralogy," Gibbs said.
“They also have ongoing contracts with the US Department of Defense, with which we are linked through our collaboration with the Defense Advanced Research Projects Agency EMBER R&D program aiming to develop a clean rare earths supply chain for the US.
“Also very pleasing is the ongoing confirmation that La Paz has very low levels of penalty elements thorium and uranium.
“This is beneficial from an environmental and handling perspective and makes our company more likely to be invited to be involved with additional US Government-supported supply chain R&D programs.
“I thank all our partners in this test work for the significant progress that's been made, and we look forward to the next round of work to refine the learnings and take the flowsheet to the next stage of development."
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