London-listed Harena Resources says metallurgical test results have confirmed that ionic clay-hosted rare earth elements (REEs) can be efficiently recovered from its 75%-owned Ampasindava project, in Madagascar, using low-impact heap leach processes such as salt water or standard ammonium sulphate solutions.

Harena, which has recently changed its name from Citius Resources, says this supports the company's goal of developing a technically robust, environmentally responsible and geopolitically independent supply of magnet metals essential to the global defence, energy and technology sectors.

The company notes that REEs at Ampasindava are readily recoverable through simple ion desorption, with high extraction rates achieved using an ammonium sulphate leach in low-acid conditions.

Main extractions were about 88% neodymium, 73% dysprosium, 67% yttrium, 86% lanthanum, with low levels of gangue, thorium and uranium supporting a clean environmental profile.

Harena says SGS Lakefield testwork using a pH 5 ammonium sulphate solution delivered strong results, including 87% neodymium, 88% praseodymium, 71% dysprosium, 75% terbium and 63% yttrium.

Encouragingly optimal column heap leach tests, over 218 hours, demonstrated recoveries of 88% neodymium, 86% praseodymium, 73% dysprosium, 79% terbium and 67% yttrium using ammonium sulphate at a pH of four.

Additionally, low-value, high-bulk cerium demonstrated minimal recovery, a significant benefit in production of a high-grade magnet metal concentrates or carbonates.

While early days in the programme, MD Joe Belladonna describes the high rare earth recovery results achieved in the SGS Lakefield testwork as “very encouraging”, demonstrating that the process to be employed at Ampasindava will be environment- and ecologically-friendly.

He says the low-risk process, simple reagents used and no requirement for a tailing storage facility should benefit the economic and technical viability of Ampasindava.

"With the current geopolitical environment, the race to secure heavy rare earth feedstocks for defence and new-energy applications is accelerating. Projects that can demonstrate both technical viability and alignment with Western supply chain priorities are increasingly in focus.

“Ampasindava's combination of critical magnet metals, clean extraction and independence from Chinese processing, gives us a timely opportunity to contribute to a more resilient global supply chain,” he says.