source:Mining review
RRainbow Rare Earths has achieved group separation of rare earth elements through initial ion exchange test work ongoing in the USA.
This achievement marks a significant leap forward in the rare earth oxide separation process, opening doors to the production of individual rare earth oxides. With a primary focus on delivering high-purity neodymium and praseodymium (NdPr) oxide, Rainbow’s back-end piloting campaign sets the stage for further advancements in separating dysprosium (Dy) and terbium (Tb) oxides.
Additionally, the potential for group separation of samarium (Sm), europium (Eu), and gadolinium (Gd) elements presents a promising opportunity for generating a combined oxide and diversifying revenue streams.
The 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.
As previously announced, Rainbow and K-Tech have identified a cerium-depleted mixed rare earth carbonate as the optimal feedstock for the back-end process, offering a higher-grade feedstock for the separation circuit.
The Phalaborwa project’s phosphogypsum has successfully produced mixed rare earth carbonate for initial separation at the back-end pilot plant. Cerium, a material shipped to K-Tech from the Council for Mineral Technology’s Johannesburg plant, is currently under test at both K-Tech and Mintek. The cerium-depleted carbonate, once available, is expected to yield better results in the CIX and CIC separation circuits. The back-end plant process comprises three main stages.
George Bennett, CEO of Rainbow, commented:
“I am very pleased with the continued progress to date in validating our front-end process flow sheet and the K-Tech CIX/CIC process flow sheet for the back end. The back-end process is on track to deliver separated high-purity rare earth oxides of NdPr, Dy, and Tb, the four most economically important rare earth elements due to their crucial role in the green energy transition.
“It is also notable that we have achieved positive separation in the chromatography circuit of the SEG group of rare earth oxides, which could add another very saleable product and revenue stream to Rainbow at minimal cost,” said Bennett.
The current focus of the pilot plant test work at K-Tech aims to optimise the second stage of chromatography to produce a 99.5% NdPr product, followed by CIC testing to separate and purify Dy and Tb oxides.
In addition, the production of a separated and purified SEG oxide product will be evaluated and followed up. Initial indications are that Phalaborwa could produce 500 tonnes per of a saleable SEG product annually, in addition to the previously announced residual gypsum off-take, which presents an additional revenue stream with minimal capital and operating costs.