Rare Earths Oxide Produced from Halleck Creek Ore-Major Technical Breakthrough

MREO from Halleck Creek (“the Project”) was produced using the material – a pregnant leach solution (“PLS”) – from the impurity removal testing campaign³. This was achieved through precipitating a mixed rare earth oxalate and then creating MREO powder (see Figure 1). This major technical milestone confirms that rare earths can be extracted into metallic oxides from Halleck Creek ore using the updated preliminary PFS mineral processing flowsheet currently being finalized for the upcoming PFS. Solvent extraction computer simulation is now underway, using the results of these tests.

SGS in Lakefield, Ontario, Canada created the MREO from the Halleck Creek PLS through a two- step process. The first step consists of precipitating the metals in solution using oxalic acid to create a mixed rare earth oxalate. Oxalic acid is highly selective in precipitating rare earth elements (“REE”) from PLS while other elements stay in solution. SGS performed three precipitation tests using variable oxalic acid addition rates. The second step, called calcining, involved SGS heating the combined mixed rare earth oxalates to 1,000oC to oxidize the material into a MREO. A beneficial effect of calcining is that it oxidizes the cerium, converting it from Ce³+ to Ce⁴+. Ce⁴+ is not soluble in the reagent which will be used to dissolve REEs from the MREO for solvent extraction.