Name of the Project
Phalaborwa rare earths project.

Location
Limpopo, South Africa.

Project Owner/s
London-listed Rainbow Rare Earths announced the signing of a binding agreement with Bosveld Phosphates for the co-development of the Phalaborwa rare earths project in November 2020.

On completion of a prefeasibility study (PFS), 70% of the project will be held by Rainbow and 30% by Bosveld, with a mechanism included to allow for Rainbow’s joint venture ownership to vary from 60% to 85%, depending on the results of the PFS.

Project Description
Rainbow Rare Earths and Bosveld Phosphates intend to jointly develop and process rare-earth elements (REEs) from the gypsum contained in two stacks at the project site.

Technical work undertaken to date has confirmed an inferred mineral resource estimate at Phalaborwa of 38.3-million tonnes at 0.43% total rare-earth oxides (REOs) contained within gypsum tailings stacked in unconsolidated dumps, derived from historic phosphate hard-rock mining.

High-value neodymium and praseodymium oxide represent 29.1% of the total contained REOs, with economic dysprosium and terbium oxide credits enhancing the overall value of the rare earth basket contained in the stacks.

Metallurgical testwork has confirmed that the phosphogypsum at Phalaborwa is amenable to direct leaching with acid to extract the contained rare earths.

The reprocessing of these gypsum stacks carries significant environmental benefits, as it will redeposit clean, benign gypsum, which then has the potential for further use in the building and fertiliser industries.

Potential Job Creation
Not stated.

Net Present Value/Internal Rate of Return
Not stated.

Capital Expenditure
Not stated.

Planned Start/End Date
Not stated.

Latest Developments
Rainbow Rare Earths has recorded positive results from the ongoing phased testwork programme at its Phalaborwa project.

The testwork is being conducted in conjunction with Australia-based critical and strategic metals processing expert ANSTO Minerals and US-based processing technology developer K-Technologies (K-Tech).

The results of the testwork are enabling Rainbow to develop an economic rare earths extraction flowsheet as part of the feasibility study for the project.

Results, to date, have provided the company with additional optimisation opportunities to explore.

The next phase of the testwork programme is under way and includes several trade-off and project optimisation studies.

Key findings include strong recoveries and optimisation opportunities.

The testwork by ANSTO has confirmed that a simple acid leaching process is expected to allow for 65% to 70% of the rare earths contained in the Phalaborwa gypsum stacks to be recovered in solution, with an average 66% leach recovery reported from preliminary metallurgical variability testwork.

The K-Tech purification and separation desktop study has confirmed the ability to deliver separated rare earths with more than 99% purity oxides from the leach solution. Phalaborwa will be unique in producing separated neodymium and praseodymium oxide, dysprosium oxide and terbium oxide on site.

This will allow for the full value of the rare earths to be realised – a 47% increase in revenue over the expected sales price for a mixed rare earth carbonate.

Trade-off studies have started at ANSTO and K-Tech to determine the optimal method to maximise the grade of rare-earth elements in the leach solution before the final K-Tech separation step while managing the build-up of impurities in the gypsum stacks that could impact overall rare earth recovery.

Increasing the leach solution grade by recycling the leach solution will significantly reduce operating and capital costs.

Moreover, the testwork has indicated reduced capital and operating costs, with flexibility in terms of project development.

The phosphogypsum will be hydraulically reclaimed from the stacks and pumped into the processing facility, reducing the cost per tonne, compared with traditional hard-rock mining.

Nano filtration will successfully recycle more than 60% of the sulphuric acid required to recover the rare earths to the leach solution, reducing operating and capital costs and minimising leach solution flows into the downstream K-Tech separation circuit.

Potential has been identified for phased development, consequently providing versatility.

Sulphuric acid remains the lixiviant (leaching liquid) of choice following this testwork, owing to the low cost and availability of the reagent in the local area and the simpler materials of construction requirements.

With a slight elevation to the temperature of the sulphuric acid leach solution, recovery is optimised with a 12-hour leach residence period, providing significant operating and capital cost savings compared with the initial 24-hour leach residence period originally envisaged at atmospheric temperature.

The testwork also shows environmental benefits.

Water neutralisation testwork has confirmed the ability to treat the existing water from the stacks and reuse it in a closed circuit as plant process water, thereby reducing the substantial legacy issue of acid water from historic work, and reducing overall freshwater use in the flowsheet.

Very low levels of radioactivity have been confirmed within the gypsum extracted, significantly below the International Atomic Energy Agency guidelines, consequently exempting the project from regulation pertaining to radioactivity.

Key Contracts, Suppliers and Consultants
ANSTO Minerals (flowsheet process optimisation) and ANSTO Minerals K-Tech (testwork programme).

Contact Details for Project Information
Flagstaff Strategic and Investor Communications on behalf of Rainbow Rare Earths, tel +44 207 129 1474 or email rainbowrareearths@flagstaffcomms.com.