Red Metal says new test results back its belief that the Sybella rare earth mineralisation near Mount Isa can be extracted by low-cost heap leach processing, providing impetus to fast-track pre-feasibility studies.

Large column leach tests using weak sulphuric acid at ambient temperatures have achieved strong rare earth extractions on representative, coarsely crushed ore samples from the Sybella Kary Zone.

“Our column leach tests on the Kary Zone ores have conclusively shown that we can efficiently extract light and heavy rare earths from the mineralised granite by coarsely crushing it, stacking it and then leaching it with weak sulphuric acid at ambient temperature,” Red Metal managing director Rob Rutherford said.

“Our ongoing studies hope to show Sybella is the Escondida of rare earths, and we will now embark on additional, more detailed mining and metallurgical studies to determine just how low-cost and economic this very large rare earth development could be.”

Between 35 per cent and 55 per cent total rare earth extraction occurred within the first 30 days of column tests, highlighting scope for early cashflow once the heap is set up.

Red Metal said analysis of the inferred mineral resource estimate at a 300ppm NdPr cut-off grade showed the Kary Zone at Sybella contained:

• 182Mt at 331ppm NdPr (neodymium-praseodymium oxide) and 30.8ppm DyTb (dysprosium and terbium) of saprock from surface, and
• 157 Mt at 337ppm NdPr and 31.9ppm DyTb of transitional ores.

The company said this large resource of at-surface, friable rare earth mineralisation – which remains open towards the south-east -would provide many years of early-mine feedstock.