The adoption of renewable energies (e.g. solar and wind) is gradually increasing as the world continues to decarbonise; however, one limiting factor is its intermittency. This issue can now be readily addressed using vanadium flow batteries (VFBs), which act as a bridge between the fluctuating nature of renewable energy and the stable, predictable energy demands of modern systems. VFB is a type of rechargeable battery known for their scalability, long lifespan, and ability to store large amounts of energy. High purity vanadium (HPV, 99.5% V2O5) is a critical feedstock for the manufacture of VFBs, and their demand is rising alongside the growth of renewable energy technologies.
Australian Vanadium Limited (AVL) is developing the Australian Vanadium Project in Western Australia with complete vertical integration (pit to battery pack) strategy, from vanadium mining and processing (upstream), vanadium electrolyte manufacturing (midstream) to VFB production (downstream). AVL was awarded a federal government grant in 2021 to build a vanadium electrolyte manufacturing plant using HPV feedstocks.
ANSTO has supported AVL to develop and test a continuous solvent extraction process for HPV recovery using a tertiary amine extractant at the mini-pilot plant scale. The aqueous feed to the solvent extraction mini-pilot plant represented the process liquor emanating from heap wash stage of leach solids that was produced from an earlier salt-roast pilot of vanadium titanomagnetite concentrate from the Australian Vanadium Project.
Chromium was the most notable impurity that needed careful management in the solvent extraction process. The enriched (loaded strip) liquors containing high purity ammonium decavanadate was further treated with aqueous ammonia to produce ammonium metavanadate intermediate and then calcined to yield the final product with a purity greater than 99.9% V2O5 (considered as ultra-high purity vanadium, UHPV).
The operational and technical performance of the solvent extraction mini-pilot plant to recover HPV for VFB electrolyte production is reported in this paper.