Modern Mining August 2021

RARE EARTHS

Phalaborwa Rare Earths Project: PEA to Rainbow Rare Earths Ltd has announced the commencement of work on the Preliminary Economic Assessment (PEA) for the Phalaborwa Rare Earths Project in South Africa. The PEA will compare a conventional route to produce a cerium-depleted mixed rare earths carbonate with an alternative flow sheet that bypasses the carbonate stage and delivers three higher value products – neodymium-praseodymium (NdPr) oxide, terbium (Tb) oxide and dysprosium (Dy) oxide. By Mark Botha .

T he project comprises 38,3-mil- lion tonnes (t) of gypsum resulting from historic phosphate hard rock mining and containing rare earth elements with an estimated average in situ grade of 0,43 – 0,45% total rare earths oxide (TREO), based on previous

Rainbow Rare Earths earning 70% on completion of a successful prefeasibility study. The company will enter inro a joint venture with Bosveld Phosphates (Pty) Ltd. The 38,3-million t of gypsum residue resulted from around 60 years of hard rock mining of a phos- phate deposit by South African government-owned mining company Foskor (Pty) Ltd. There are trace elements of RE’s in the hard rock deposit but not in economic quantities. The phosphate rock was concentrated via a flo- tation process to produce a phosphate concentrate slurry (also concentrating the rare earths) which was pumped to a nearby phosphoric acid production plant run by energy and chemical company Sasol Ltd. “In the production of phosphoric acid, which is used in the fertiliser industry, a lot of heat and sulph- uric acid were added, thereby effectively ‘cracking’ the rare earths in their mineral form to now be found in the gypsum residue (the waste stream of the phos- phoric acid production process) as ‘cracked’ rare earths in chemical form,” says Bennett He says the gypsum residue went through three stages in the phosphoric acid production process to

George Bennett, CEO of Rainbow Rare Earths.

sampling campaigns and supported by assay results, of which some 29,1% comprises high-value NdPr. Rainbow Rare Earths CEO George Bennett says the rare earths are contained in chemical form in the gypsum stacks, which he expects will deliver a higher-value rare earth carbonate, with lower oper- ating costs than a typical rare earth mineral project. The results of the PEA, says Bennett, are expected by end-October 2021: “We are a bit behind schedule due to test work delays at the Australian Nuclear Science and Technology Organisation (ANSTO) in Sydney, Australia, having shut down for between two and six weeks due to COVID-19 lock- downs. Failing more delays due to Covid, we should make end October 2021.” Project background He says the project is an earn-in agreement with

The gypsum stacks at the Phalaborwa Rare Earths project.

16  MODERN MINING  August 2021