By Dr Troy Coyle, HERA CEO

In an August episode of the HERA podcast, Stirring the Pot, I spoke to Paihau-Robinson Research Institute junior engineer Megan Girdwood, a chemical and process engineer. Megan recently submitted her Masters thesis on chemical engineering, and her current project is to develop a closed-loop, green process to extract vanadium from a co-product of the New Zealand steel-making process.

Megan described vanadium as the most high-value byproduct, noting there are other companies looking into titanium slags, and making titanium dioxide as a pigment for paints and dyes.

The biggest application of vanadium is in steel alloys, Megan said: “Just a small amount of vanadium added to steel can double its strength. This makes it really good in lightweight and high-strength applications and also titanium alloys. Then the up-and-coming market is vanadium redox flow batteries, which will be used to store renewable energy on a large scale in the future.”

New Zealand steel produces about two percent of the world’s vanadium slag, approximately 14,000 tonnes per year – which is shipped overseas for processing. Most of this is then bought back by steel mills at an average cost (in 2019 figures) of around NZ$30,000 per ton of vanadium pentoxide.

Megan’s research involves finding a sustainable closed-loop process to extract vanadium from steel slags, producing no waste water or toxic waste streams. She told me the research has “been getting really high extraction efficiencies . . . and high purity of vanadium pentoxide, so it’s a great product as well. The only by-product is an iron-rich residue, which can go back to the steel mills” – making it a circular-economy contributor. And as a green process, it can be consented to be done anywhere – including potentially in New Zealand.

The process has been proven in the laboratory, and the next step is a pilot plant to make sure it can work at a commercial steel mill scale. Megan says she is mindful of a future challenge: as the global industry works towards using hydrogen as a reductant in place of coal, a new steel slag will be produced – so a new vanadium extraction method will likely be needed to work with the new steel process. Megan says, “I’m excited for that – to have a fully green steel and vanadium extraction unit.

For my full discussion with Megan, including technical aspects of vanadium extraction and disposal, check out the Stiring the Pot podcast.

Dr Troy Coyle brings more than 20 years’ experience in innovation management across a range of industries including materials science, medical radiation physics, biotechnology, sustainable building products, renewable energy and steel. She is a scientist with a PhD (University of NSW) with training in journalism and communications.