Successful Completion of Phase I Rare Earth Separation and Processing Test Work

Results Provide Baseline for the Pilot Plant Operation at USA Rare Earth’s Facility in Wheat Ridge, Colorado


May 26, 2020


USA Rare Earth, LLC, the funding and development partner of the Round Top Heavy Rare Earth and Critical Minerals Project in West Texas, together with Texas Mineral Resources Corp. (OTCQB: TMRC), is pleased to announce that it has successfully completed its Phase I bench scale testing at Inventure Renewables, Inc.’s laboratory in Tuscaloosa, Alabama. This phase of work utilized feed solutions produced from pilot heap leach columns processing ore from Round Top.


This important milestone demonstrates the ability to load and concentrate rare earths (REE’s) in the presence of high concentrations of non-REEs, including other critical minerals such as lithium. REE concentrations were increased more than six-fold with a commensurate reduction in impurities. Weak acid rinsing demonstrated enhanced separation of REE’s from non-REE’s.

“This is an important step towards USA Rare Earth’s objective to build the first rare earth and critical minerals processing facility outside China and to bring the Round Top project into full commercial production,” said Pini Althaus, CEO of USA Rare Earth. “Our Colorado pilot plant will have the ability to produce the full range of high purity, separated rare earths as well as other critical minerals such as lithium.


“I especially want to commend our team for maintaining such an aggressive development timetable, even as we all cope with the COVID pandemic,” Mr. Althaus continued.


These results provide the baseline for initiating the Pilot Plant operation at USA Rare Earth’s rare earth and critical minerals processing facility in Wheat Ridge, Colorado. The first of three Continuous Ion Exchange (CIX) Pilot Plant units was delivered in early March and is planned to be commissioned in early June as Covid-19 related travel restrictions are relaxed. The 30-column units readily enable rinsing, washing and solution recycling in a fully automated process which greatly simplifies the optimization of the process now that the base case parameters have been established in the laboratory.


Richard Shaw, principal of Fenix NZ stated, “The success of this first phase of work, concentrating the rare earths and obtaining a clean separation from other minerals, is an important validation of our processing, using CIX. The Ion Exchange process is widely used in other industries and has been used in China and elsewhere to achieve high purity separation of rare earths. In the coming months, we expect to achieve the goal of separated, high purity rare earth compounds and other targeted metals such as lithium as we scale up towards a commercial pilot plant.”


USA Rare Earth has a three-pronged mine-to-magnet strategy to establish a resilient, 100%-domestic supply chain for rare earth magnets, which are essential for modern manufacturing ranging from defense applications, wind turbines, electric vehicles, smart phones, and in many medical devices.


Restoring a 100% U.S.-Based Rare Earth Supply Chain


“Our pilot plant is the second link in a 100% U.S.-based rare earth oxide supply chain, drawing on feedstock from our Round Top deposit. Together with our recently acquired rare earth magnet platform, Round Top and our pilot plant constitute essential links in restoring a mine-to-magnet domestic U.S. rare earth supply chain without the material ever leaving the United States, thereby alleviating the current dependence on China for the both raw materials and mineral processing. Aside from Round Top’s potential to supply a significant amount of material for U.S. defense as well as commercial applications, we believe our initiative will reinvigorate advanced technology manufacturing in the U.S. for companies currently dependent on foreign sources for supply,” Mr. Althaus continued.


Under Defense Logistics Agency (DLA) and Department of Energy (DoE) grants, the CIX/CIC process successfully produced high-purity (99.99% or 99.999%) rare earth compounds from material from Round Top and other sources. The pilot plant work currently underway builds on that expertise and includes the Phase 1 initial process preparation to separate REEs from other minerals, including targeted metals such as lithium.


The CIX/CIC units at the Wheat Ridge pilot facility are capable of processing several thousand liters of leach solution per day. The CIX process concentrates large volumes of leach solution to smaller volumes of higher grade solution. Continuing leach optimization studies have identified improvements through the controlled addition of acid to maximize REE’s in solution while minimizing and separating other elements.


The next phase of USA Rare Earth’s pilot work will focus on group separation into heavy (dysprosium, terbium), middle, and light REE’s (neodymium, praseodymium). The third and final phase of the pilot work will be the further separation of high purity individual REE compounds.


Process work to recover the non-REEs that have been separated from the REEs in the Phase 1 work will continue in parallel. Completion of this work – which will focus on lithium, uranium, beryllium, gallium, zirconium, hafnium and aluminum, all of which are on the U.S. Government Critical Minerals List -- will support a Preliminary Feasibility Study, including non-REE processing that is expected to support upgrading the measured and indicated resources to proven and probable reserves, with no in-fill drilling required.


Summary of Successful Phase I Test Work


USA Rare Earth contracted Inventure Renewables, Inc. to develop continuous ion exchange/chromatography (CIX/CIC) processes for the separation and purification of rare earth elements (REEs) from non-rare earth elements (non-REEs). The development of these processes utilizes pregnant leach solution (PLS) that is generated by Resource Development Inc (RDi) using ore from the Round Top deposit that has been leached using sulfuric acid in columns, simulating heap leach conditions.


Inventure conducted a series of laboratory scale tests across a range of acidities to look at the optimal loading and separation of REE’s from non-REE’s. As expected, higher pH’s resulted in a higher overall mass loading (including non REEs) while lower pH’s improved selectivity for REEs, with pH 1.0 an optimal compromise between mass loading onto the resin and the selectivity of the REEs over the non-REEs. However, the near-optimal operating range is broad, demonstrating the robustness of the process.


40 column bed volumes (BV’s) of the PLS were passed through the resin bed in the column before rinsing and eluting with sulfuric acid. The results of which were plotted below and “normalized”, enabling the data to be plotted on the same scale, so that the relative impact of the REE’s and non-REE’s can be directly compared. In Figure 1, a C/C0 value of 1.0 represents the initial concentration in the PLS and the graph shows the elution was significantly completed after 3 bed volumes with a 6.3-fold increase in REE concentration compared to the PLS feed. This increased concentration is expected to further improve with leach optimization, maximizing loading of the resin by increasing beyond 40 bed volumes of leach solution, and recirculating portions of the REE-rich eluate to crowd off non-REEs in the multi-column pilot plant. As previous laboratory wok demonstrated that effective separation and purification of the REE’s could be achieved directly from the PLS, these upgraded solutions should provide an excellent starting point for the chromatographic separation of specific REE’s.




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