Highlights

• Rainbow Rare Earths successfully developed a cerium rejection step that reduces material volume by 27% and improves processing efficiency.
• Phalaborwa project leverages unique phosphogypsum waste feedstock to create a high-purity mixed rare earth product with >55% TREO.
• The company aims to produce NdPr oxide and a heavy rare earth stream by Q4 2025.
• Targeting critical minerals for EV, wind turbine, and defense technologies.

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Rainbow Rare Earths Limited (opens in a new tab) (LSE: RBW) has announced a major technical advancement at its flagship Phalaborwa project in South Africa: the successful incorporation of a cerium (Ce) rejection step in its processing flowsheet. This innovation enhances the quality of Rainbow’s high-grade Mixed Rare Earth Product (MREP) by cutting Ce content by about 65%—a critical improvement since cerium is low-value yet highly abundant in rare earth ore streams.

So, why does this Matter?

Cerium rejection is not just a chemistry tweak—it fundamentally reshapes project economics. By removing Ceearly, Rainbow reduces the volume of material entering the final separation circuit by roughly 27% and cuts the flow to only 2% of the original pregnant leach solution. That means smaller, more efficient separation plants with lower capital and operating costs. CEO George Bennett called the move “a major achievement” that positions Phalaborwa as one of the world’s most efficient producers of both light and heavy rare earths.

The project is unique in its feedstock: phosphogypsum stacks, a waste product of fertilizer production. Unlike traditional mining, Phalaborwa’s resource is already chemically cracked, reducing both cost and lead time. Earlier test work confirmed an exceptionally pure MREP averaging >55% TREO (total rare earth oxides) with >93% purity. The latest cerium rejection step further strengthens the case for delivering high-value neodymium, praseodymium, dysprosium, and terbium—core inputs for permanent magnets in EVs, wind turbines, and defense systems.

Rainbow expects to finalize the separation stage of its flowsheet by Q4 2025, with commercial products to include NdPr oxide and a SEG+ heavy rare earth stream rich in dysprosium and terbium.

Key Questions for Investors:

• Will Rainbow’s flowsheet scale beyond laboratory and pilot levels, maintaining Ce rejection efficiency at industrial volumes?
• Can the company secure offtake partners for its NdPr and SEG+ products, particularly in Western markets seeking “China-free” supply?
• With cerium volumes reduced, will there be any long-term strategy to monetize Ce, or is it strictly treated as waste?
• How quickly can Phalaborwa move from test success to full commercial operation—and how might permitting, financing, or separation technology hurdles delay timelines?

Rainbow has consistently marketed Phalaborwa as the “highest margin rare earth project outside China.” With this technical milestone, the company strengthens that claim—but execution risk remains the defining factor.

Source: Rainbow Rare Earths Limited (opens in a new tab), RNS No. 1279A, September 22, 2025

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