Rare earths miner Rainbow Rare Earths has entered into a memorandum of understanding (MoU) with a diversified chemicals group to investigate extracting rare earth elements from a nitro phosphate process stream at the chemicals group’s phosphoric acid production plant near Johannesburg.

The feedstock for the phosphoric acid production plant originates from the same ore originally mined by South African group Foskor that generated the two gypsum stacks at Phalaborwa.

Direct costs associated with the pilot study conducted by Rainbow, using its exclusive intellectual property (IP) and technology, will be financed by the chemicals group.

Subject to a successful outcome, Rainbow and the chemicals group intend to negotiate terms for a potential joint venture agreement to extract value from the rare earths present in the phosphoric acid processing stream.

Under the terms of the MoU, Rainbow will conduct a rare earths extraction pilot study with the chemicals group, which will involve initial grade test work on processing stream material.

This will be followed by a technical programme to confirm a flowsheet using Rainbow’s knowledge and IP gained from work carried out to date at the miner’s Phalaborwa rare earths project, including the licensed K-Technologies’ separation technology.

To date, Rainbow has completed preliminary sampling of the processing stream, with initial results indicating a total rare earth oxide grade of 0.81%, with a 27% weighting to high-value neodymium and praseodymium, along with economically-viable levels of terbium and dysprosium, similar to Rainbow’s Phalaborwa project.

Rainbow CEO George Bennett says the MoU demonstrates the significance and broader application of Rainbow’s IP and technology at another project in South Africa.

“This is a very exciting opportunity for Rainbow to release additional value from a nitro phosphate processing stream by efficiently producing separated rare earths, which are currently untapped within the phosphoric acid production process.”

As at Rainbow’s Phalaborwa project, the rare earths in the chemical group’s stream are contained within an acid solution in a cracked form, which enables Rainbow to apply the rare earths separation technology, thereby facilitating a simple process with significantly fewer extraction and separation steps than a traditional rare earth mining project.

“Through our processing projects, which have fundamentally different risk profiles to traditional rare earth mining projects, we see enormous potential to facilitate near-term access to sources of critical permanent magnet rare earths, which are required to decarbonise energy systems in an environmentally responsible way,” he says.