The Uberaba project in Brazil is the subject of an MOU between Rainbow and its owner Mosaic, which was announced post Year-end.

The project is similar to Phalaborwa in that it will entail the processing of a phosphogypsum stack that is the by-product of phosphoric acid production which was originally based on a hard rock carbonatite.

Mosaic’s phosphoric acid operations are ongoing, meaning that new phosphogypsum is deposited on the stacks annually.

Due to the similarities of the feedstock, the Uberaba stack was expected to have a similar grade and rare earth element make-up as those of Phalaborwa and this was confirmed by initial assay analysis, which indicated:

  • an average grade of 0.58% TREO;
  • the basket contains all four of the magnet rare earths NdPr, Dy and Tb, with NdPr representing ca. 25% of the basket.

Rainbow and its partner Mosaic are very encouraged by these results and are therefore planning additional test work at SGS Laboratories in Toronto around the mineralogy to identify the rare earth phases and facilitate the development of a processing test programme. The costs for this initial work programme will be shared by both parties 50:50.

Under the terms of the MOU, Rainbow and Mosaic will look to jointly develop a process flowsheet to extract the rare earth elements from the Uberaba stack. Due to the similarity of the Phalaborwa and Uberaba projects, Rainbow anticipates that the majority of the Phalaborwa front-end process flowsheet (jointly developed by Rainbow and K-Tech to deliver a mixed rare earth sulphate) will be applicable, as well as the Phalaborwa back-end process flowsheet (the patented K-Tech IP which uses CIX and CIC to deliver separated rare earth oxides), which Rainbow has exclusive rights to in Brazil.

Following the production of the process flowsheet, Rainbow and Mosaic will collaborate on the production of a PEA for this opportunity to extract rare earths.

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Key facts

  • 0.58% average grade TREO
  • Nd, Pr, Dy, Tb basket contains all four magnet REEs
  • 25% proportion of NdPr within the basket