US rare earth strategy and Rainbow’s Phalaborwa: cost and metallurgy lens for engineers
Reviewed by Joe Ashwell

First reported on MINING.com
30 Second Briefing
US backing for Rainbow Rare Earths’ Phalaborwa project in South Africa signals a shift from tonnage-led to metallurgy-led rare earth strategy, with $50 million of US equity supporting recovery of Nd and Pr from a 35‑million‑tonne phosphogypsum stack. The project leverages prior mining and fertiliser processing, negligible Thorium/Uranium in the feed, and a proprietary cerium‑depletion step removing about 65% of low‑value Ce to target operating costs below US$30/kg Nd+Pr. Coupled with a US$500 million US‑Africa Strategic Investment Program, this points to supply‑chain resilience built on cost‑competitive, international partnerships rather than purely domestic deposits.
Technical Brief
- Phalaborwa’s 35 Mt phosphogypsum stack is an above-ground “artificial orebody”, avoiding new pit development and primary crushing.
- Historic fertiliser operations already completed ore extraction, comminution and phosphoric acid leaching, shifting capex focus almost entirely to REE recovery circuits.
- Rainbow Rare Earths’ flowsheet targets early cerium rejection via a proprietary depletion step, decoupling economics from natural La–Ce dominance.
- Negligible thorium and uranium in the phosphogypsum sidestep NORM handling, tailings licensing and long-term radiological stewardship typical of many REE projects.
- Ionic adsorption clays are cited as benchmarks because weakly bound REEs enable low-temperature leaching without roasting, cutting energy intensity versus hard-rock carbonatites.
Our Take
Rainbow Rare Earths also appears in our coverage via TechMet’s planned $200 million raise for a broader critical minerals portfolio, signalling that Phalaborwa is being positioned within a multi-asset, multi-jurisdictional supply chain rather than as a standalone bet on South Africa.
With Washington’s $50 million equity into Phalaborwa sitting alongside a $500 million US-Africa Strategic Investment Program envelope, the US is effectively using South African rare earths to complement emerging domestic plays like Rare Earths Americas’ Shiloh/Foothills district, diversifying away from a single-country supply strategy.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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