King River Resources Ltd’s (ASX:KRR) metallurgical results continue to support advancing a new vanadium-titanium-iron development plan for its Speewah Vanadium Project in the East Kimberley of Western Australia.
The company has been conducting sulphuric acid (H2SO4) bottle roll and diagnostic vat leach tests on magnetite-ilmenite concentrate and coarse magnetite gabbro lumps from the high-grade zone of the Central Vanadium deposit.
This test work was designed to assess whether the Speewah magnetite gabbro is best suited for vat or heap leaching prior to completing laboratory diagnostic vat and column leach tests.
Notably, bottle roll sulphuric acid leaches on run of mine (ROM) magnetite gabbro lumps that have been crushed to sizes of 10mm, 5.6mm and 3.35mm report 77%, 84% and 84% vanadium extractions (dissolved) respectively.
Observations and conclusions that can be drawn from the bottle roll test results include the following:
• Vanadium, titanium, iron, magnesium and aluminium leach efficiencies (extractions) are very good and support advancing the test work on lump material; and
• The vanadium and titanium extractions increase as the lump or grain size decreases for the same time interval.
Vat leach test work
King River’s diagnostic heated vat leach test work on 3.35mm and 5.6mm lump samples will allow the critical process parameters to be adjusted and recorded.
The initial diagnostic vat results show:
• Up to 92% vanadium and 61% titanium leach extraction after 10 days (240 hours); and
• Higher leach temperature and maintaining acid at 150-200mg/L have significantly increased the leaching rate of all metals.
King River’s board is encouraged by the bottle roll and vat leach test results to date and will now fast-track the vat and column leach test work.
This will enable the vat leach plant design and costings to be finalised as soon as possible.
A trade-off analysis into the optimum particle size will also be undertaken.
There may prove to be some potential to use a coarse 2mm concentrate for the vat leach operation as it would significantly reduce the amount of material leached and possibly shorten leaching times.
A 2mm concentrate beneficiation plant would also be a simpler design to the facility used in the recently released vanadium scoping study that generated a 106 micron (~1/10th of a mm) concentrate.
Alternatively, if lump ROM material was chosen in the coming months to be the most economical option to be used in the PFS (pre-feasibility study), then there will be no fine grinding or magnetic separation circuit required.
During 2019, KRC aims to present shareholders with the most prudent commercial strategy to develop the Speewah vanadium deposits and advance towards the production of vanadium, titanium and iron products at the lowest possible unit cost.