AVL’s mechanical water leach circuit has been shown to be a viable, cost-effective design, maximising onshore Australian extraction of high-value critical mineral vanadium products.
This marks a major milestone in final pilot test-work programs and allows the company to conclude final work activities for the bankable feasibility study (BFS), including final processing designs, mass balances and detailed costings.
The water-leach and wash processes impressively removed 99% of soluble vanadium from the iron-titanium co-product, enhancing its value for direct use in steelmaking.
This demonstrates AVL’s mechanical water leach circuit to be a viable, cost-effective design, maximising onshore Australian extraction of high-value critical mineral vanadium products.
The work was conducted at ALS testing facilities in Perth – a research partner in AVL’s Australian Government’s Cooperative Research Centre Projects scheme entitled: ‘Production of 99.95% Pure Vanadium Pentoxide and Vanadium Electrolytes’.
Results compare favourably
Speaking to the results, managing director Vincent Algar said: “The success of this phase of the water-based leach of AVL’s pelletised concentrate compares very favourably to other global operations that process vanadium from vanadium titanium magnetite deposits.
“Combined roast and leach extractions reported elsewhere are generally under 90%, with extractions usually in the low to mid-80s, supporting a significant advantage for the Australian Vanadium Project, having demonstrated overall vanadium extraction of 92%.
“These latest positive outcomes finalise key technical aspects of the BFS flowsheet design.
“A robust and well-supported process engineering design pushes AVL further ahead towards the successful commencement of the project.”
Pilot process
The AVL water-based leach process is divided into two stages – the first pilot stage was run in May 2021 and comprised a rotating drum leach on a salt-roasted vanadium concentrate. This recovered the majority of the vanadium in the plant feed.
Leach residue from stage-1 was then tested in 1-metre columns to simulate a counter-current washing process, where the remaining vanadium and soluble metals are removed from the FeTi coproduct for an overall soluble vanadium extraction of 99%.
These and ongoing scaled up column water-wash test results will be used to model the final circuit design.
This full-scale design will be a series of water irrigated stockpiles of iron-titanium coproduct, arranged in a counter-current format.
Next steps
Current results demonstrate an overall vanadium roast-leach extraction of 92% is achievable, with the unrecovered vanadium locked in silicates and iron oxides.
Work has also begun on open circuit testing of a 5.5-metre column leach and will soon be followed by testing in counter-current mode.
These additional tests are designed at the full scale proposed heap height to confirm optimised leach conditions and scale-up relationships from the 1-metre column counter-current program.
This subsequent phase of leaching test-work will allow the AVL team to finalise the mass, energy and water balance for the project’s vanadium leach extraction process to a higher level of certainty.
The vanadium leachate from the test-work is being used simultaneously for selective vanadium salt precipitation, de-ammoniation and barren solution treatment test work programs.
This work will finalise the BFS design of the full-scale circuit and produce a high-purity V2O5 product to generate final marketing samples.
Significant amounts of AVL’s iron-titanium coproduct have been generated by the pilot leach program, samples of which are destined for blast furnace customer testing in Asia.
Vanadium pentoxide (V2O5) products will be analysed and used for specific customer testing in vanadium redox flow battery and specialty chemical applications.
