JOHANNESBURG (miningweekly.com) – The rare earths recovery project which is underway in South Africa’s Limpopo province, is seen as one of the world’s most resilient rare earths projects at a time when these elements are in widespread demand in permanent magnets to help the world go green.

Rainbow calculates that it has a highly economic grade of rare earths in the gypsum stacks at Phalaborwa, where the 25-million-tonne resource provides for 16 years of recovery of four of the world’s most sought after rare earth elements (REEs).

Some 150 000 t of these rare earths will be produced at an operating expenditure (opex) believed to be the lowest of any project in the West and probably even below that of the East.

Two months ago, even when the prices of the two key permanent magnet REEs – neodymium and praseodymium –  were at $47/kg to $48/kg, Rainbow would have been profitable had it been in production.

Prices have since recovered to about $60/kg for the two elements, which in 2022 were at $180/kg, all the forecasts are for rising rare earth prices.

“We believe this is one of the most resilient rare earths projects in the world,” George Bennett, the CEO of the London-listed South Africa-led Rainbow Rare Earths, proclaimed at this week’s Mintek@90 event, covered by Mining Weekly. (Also watch the attached Creamer Media video.)

“The fact that we could achieve such a low opex makes this project very resilient. At the moment, no rare earth projects in the world are making money at current rare earth pricing,” he said.

A large-scale pilot plant, which has been built as part of Rainbow’s close collaboration with Mintek since 2022, operated at the high level of 20 kg per hour of feed, making it six to ten times the size of a normal pilot plant. A reclaim trial run on the phosphate gypsum was run in February this year very successfully and the plant will be rerun in January/February to prove up final stage separation.

Involved is the first commercial recovery of REEs from phosphogypsum, which makes Rainbow Rare Earths something of a pioneer.

The availability of phosphogypsum is the result of the mining of a hard-rock phosphate deposit, which has been carried out by Foskor for the last 60 years.

The mined material is concentrated through a flotation process into a phosphate slurry, which over the period has been the feed for a nearby phosphoric acid plant, where two key ingredients were added, namely sulphuric acid and heat to create phosphoric acid.

The rare earths in the phosphate slurry were further upgraded in the phosphoric acid sludge in the phosphoric acid plant and then that phosphoric acid production created a gypsum waste residue that was transported in a concentrated form to the gypsum stacks.

The event was held to mark Mintek’s nine decades of pioneering contributions in the minerals and metallurgy sector by South Africa’s Council for Mineral Technology, which derives its mandate from the Minerals Technology Act.

In conjunction with Mintek, Rainbow has developed a one-of-a-kind flowsheet that enables the commercial extraction of key rare earths out of the phosphogypsum.

Displayed on a large screen was an old opencast mine that had been mined for many years, an old Sasol phosphoric acid plant that had not been operating for ten years and two unlined environmentally hazardous gypsum stacks.

“Rainbow’s project’s going to clean this all up into a very environment-friendly state,” Bennett promised.

The ready-fenced and power-lined site has a high-voltage switch yard, reflecting the considerable advantages of being on a brownfield location.