Rainbow Rare Earths commences separation work at US pilot plant

This back-end plant process utilises continuous ion exchange (CIX) and continuous ion chromatography (CIC) to produce separated rare earth oxides. The innovative application of this established technology has been pioneered by K-Tech in the rare earth space and replaces traditional solvent extraction which uses toxic and flammable solvents and diluents and requires more than 100 separate stages. The process will produce all four of the critical rare earths used within permanent magnets, beingneodymium and praseodymium (together NdPr), dysprosium (Dy) and terbium (Tb).

Bench scale testwork carried out by K-Tech is already showing positive rare earth oxide separation in line with expectations. The continuous run of the CIX / CIC pilot plant has also now commenced. The first separated oxides to be delivered will be the NdPr, expected within the coming weeks, while the Dy and Tb will follow thereafter due to their presence in smaller volumes within the rare earth basket.

The front-end pilot plant, which is situated at the Johannesburg facilities of the Council for Mineral Technology (Mintek), a global leader in mineral processing, extractive metallurgy, and related fields, has successfully completed the first two of three planned campaigns, from which ca. 5.75 kg of mixed rare earth carbonate have been shipped to K-Tech in five batches to date.

The front-end will start running on a continuous basis from the week commencing 15 January 2024. This integrated, whole-circuit campaign will produce increasing volumes of mixed rare earth carbonate to ship to K-Tech over the course of 1Q24.

The pilot plant process is an iterative process that allows for continual optimisation in order to deliver the most efficient final flowsheet for commercial scale operations. As part of this process, Rainbow has worked with its partner K-Tech to establish the optimal mixed rare earth product for the back-end CIX / CIC system. Having first successfully produced a mixed rare earth sulphate, it was decided to further beneficiate the product, removing certain unwanted elements, with the optimal end product for separation agreed as a cerium-depleted mixed rare earth carbonate, providing a higher-grade feedstock to the back-end separation circuit.

The inclusion of this extra processing step into the front-end process does not add any significant capital or operating expenditure to the front-end flowsheet, but reduces the quantity of mixed rare earths to be processed in the CIX / CIC circuit by approximately 40%, with resultant capital and operating cost benefits.

The four rare earths that will be produced at Phalaborwa – NdPr, Dy and Tb – are all designated as critical minerals further to their important role in the transition to the green economy. As vital components of permanent magnets, these rare earth elements are used within electric vehicles and wind turbines, as well as many other advanced technologies including those required for strategic defence purposes, such as guided missiles, drones, electronic displays, sonar, and jet fighter engines.

George Bennett, CEO of Rainbow, commented: “Whilst we have experienced some delays from the original timetable due firstly to the further beneficiation of the mixed rare earth sulphate to produce a cerium-depleted mixed rare earth carbonate as the optimal feedstock for the K-Tech CIX and CIC circuits, plus two key mechanical issues at K-Tech, which took longer to resolve than anticipated due to the Christmas period, this has in no way affected the integrity of the process flowsheet which is progressing as planned. During this time, we have continued with front-end plant optimisation work in order to deliver the most efficient final flowsheet for commercial operations, as well as ongoing shipments of mixed rare earth carbonate to K-Tech. We look forward to providing updates on the pilot plant milestones during 1Q24.”

Tom Baroody, President and CEO of K-Tech, commented: “We are delighted to have commenced operations, and separation of the Phalaborwa material is progressing as planned. The delivery of all four separated rare earth oxides, neodymium, praseodymium, dysprosium, and terbium, on US soil will be a major milestone in the development of an independent and ethical supply chain of critical rare earths for the West and we are very excited about the role our technology can play in making this happen.”

Read the article online at: https://www.globalminingreview.com/mining/12012024/rainbow-rare-earths-commences-separation-work-at-us-pilot-plant/