The plant, to be operational within the coming 90 days, is located in Wheat Ridge, a suburb of Denver, and will use continuous ion exchange/continuous ion chromatography (CIX/CIC) processing technology to purify rare earths, lithium and other minerals leached from ore originating at the pair's Round Top project outside El Paso, Texas.

The JV is working in tandem with Inventure Renewables, Fenix NZ Limited, Resource Development and Pro Solv Consulting on the design, with the goal of being able to purify a total of 26 different recoverable elements.

Its ultimate target is to move the pilot facility to Texas and scale it to a full industrial capability. For now, officials said, Denver was ideal.

"The Denver area has long been the centre of mineral technology for the United States and offers excellent infrastructure and support for the mining industry," TMRC CEO and Round Top project manager for USA Rare Earth Dan Gorski said.

"We look forward to being able to efficiently utilise the resources of such diverse institutions as the Colorado School of Mines, the United States Geological Survey (USGS) and other locally based private groups as our project advances."

USA Rare Earth CEO Pini Althaus noted that the plant in Wheat Ridge was the second element of a 100%-US-based rare earth oxide supply chain.

"Taken together, we believe Round Top and our pilot plant constitute essential links in restoring a domestic US rare earth supply chain, extracting rare earths and processing them into individual REE oxides - without the material leaving the United States, thereby alleviating the current dependence on China for both raw materials and mineral processing," he said.

"Aside from Round Top's potential to supply material for US defence, as well as commercial applications, our initiative could reinvigorate advanced domestic technology manufacturing in the US and provide companies currently doing business overseas with a viable alternative."

TMRC chairman Anthony Marchese said the group was in preliminary talks with potential customers currently processing their materials in China, and those discussions are "encouraging"; those outlets are working outside of the US because of the current lack of American capacity and capability for REEs.

Work at the new centre will build upon past applications of the CIX-CIC process, which previously demonstrated the production of highly refined (99.999% purity) rare earth elements from Round Top.

The US is reportedly the third largest rare earths producer in the world, after China and Australia.