King River Resources Ltd (ASX:KRR) has produced high purity alumina (HPA) assaying >99.99% aluminium oxide (4N HPA) from metallurgical precipitation test work on material from the Speewah Specialty Metals (SSM) Project in Western Australia.
The company is investigating both vat leach of lump material and agitated tank leach of concentrates using sulphuric acid.
Scoping level capex and opex costings have supported the agitated tank concentrate leach option as the preferred process route to produce vanadium pentoxide (V2O5), titanium dioxide (TiO2) and iron oxide (Fe2O3) products.
In addition, King River has targeted other high value specialty commodities such as high purity alumina (HPA), magnesium oxide and vanadyl sulphate.
A prefeasibility study (PFS) is underway and is examining several process routes to extract these commodities.
Metallurgical refining test work has initially focused on precipitating iron, aluminium and titanium products from the sulphuric acid leach solutions as these metals occur in the highest concentrations.
In the first HPA precipitation test TSW Analytical trialled the hydrogen chloride (HCl) gas sparging method directly on the leach solution from the 5.6mm lump flooded column leach test.
READ: King River Resources achieves high vanadium-titanium extractions in Speewah metallurgical work
This test was designed to demonstrate HPA could be extracted from the sulphate leach solutions before the solution had any other metals removed or had been pre-concentrated.
In the first stage of the process, HCl gas was bubbled through the leach solution to precipitate aluminium chloride hexahydrate (ACH).
This first ACH precipitate was dissolved in water and purified by additional HCl sparging steps to recrystallise purer ACH at each step.
The final ACH precipitate was then calcined and purified to produce high purity alumina assaying >99.99% aluminium oxide (4N HPA) purity.
King River is encouraged by this initial HPA precipitation test result, which has the potential to add a material new revenue stream to the SSM project.
Steps are currently being made to try and include aluminium and magnesium in King River’s JORC resource statements to enable these potential future revenue streams to be included in prefeasibility studies.