Taking the Pedal off the Metal: Eco-Alternatives to Mining
By Alexi Freeman
Mining finite resources is like burning the midnight oil – overdo it, and you start running on empty. But without the discovery of metal, humanity would still be rolling around in the Stone Age.
Developed over thousands of years, our ability to smelt iron into tools and infrastructure has offered innumerable advantages, though environmental disadvantages are undeniable.
Previous attempts to decarbonise Australia’s mining industry – such as former prime minister Julia Gillard’s short-lived carbon tax and minerals resources rent tax – sank like lead balloons under lobbying pressure from mining groups.
But the green balloon is rising, buoyed by an emerging generation of eco-miners, unearthing technologies disruptive enough to unsettle iron ore billionaires from their restful slumber.
Through cutting-edge solutions like urban mining, phytomining, biomining, and decarbonising steel, it’s time to strike while the iron is hot via emerging eco-sustainable practices in metal extraction and processing.
Urban Mining
Most base metals are recycled thanks to their high scrap value, including copper, aluminium, steel, lead and brass.
Yet extracting precious metals like gold, silver, platinum and palladium from e-waste remains an untapped resource. Historically, this process has been complex and hazardous, involving toxic chemicals like nitric acid and cyanide.
Enter Veena Sahajwalla, Director of the Centre for Sustainable Materials Research and Technology at the University of New South Wales. Sahajwalla has pioneered the first e-waste microfactory – disruptive technology that extracts precious metals more efficiently.
Similarly, Swiss researchers at ETH Zurich had a breakthrough when they discovered that a waste whey protein could efficiently and sustainably extract gold from e-waste.
With 0.2 grams of gold per laptop, recycling e-waste is worth its weight in gold, especially given that 1,000 laptops containing gold and 65 other valuable minerals are discarded globally every second.
Biomining
Rare earth elements (REEs) are critical components best known for their application in clean energy technologies.
The increase in global demand, high cost and dangerous waste in conventional processing is fuelling the exploration of biomining extraction methods at the Materials Research Institute of Western Australia (MRIWA).
Biomining leverages the green potential of phosphate-solubilising microorganisms (PSM) and fungi to release REEs from phosphate ores and waste mine materials.
MRIWA’s biomining study exploited a fungal species named penicillium to release REEs bound in soil. Recovered REEs – including cerium, lanthanum, neodymium and praseodymium – are critical for producing ubiquitous technologies like batteries, engines and lenses.
Bioleaching is a branch of biomining that uses bacteria to dissolve metals from sulphide ores. Barrick Gold – a Canadian mining company – has commercialised this method to recover gold with an 80% reduction in cyanide consumption whilst maintaining extraction rates comparable to traditional (and more eco-toxic) methods.
Phytomining
Plants embodying the capacity to bio-extract REEs from contaminated soil could also assist the transition from carbon-fuelled mining.
Researchers at the University of Queensland (UQ) Sustainable Materials Institute (SMI) have partnered with the Queensland Government to explore the economic potential at an industrial scale of plants to extract REEs such as cobalt, lithium and zinc.
Native species like selenium weed are exploitable for their ability to act as “hyperaccumulators”, resulting in an innovative eco-mining method known as "phytomining" – a new practice gaining significant ground in academic research and industry circles.
Benchmark Mineral Intelligence forecasts that demand for lithium will outstrip supply by 2030, necessitating the development of alternative extraction methods. Director of SMI, Professor Rick Valenta, said that phytomining is uniquely suited for addressing that role “because it introduces an abundance of new resources that can be unlocked with less invasive methods and allows the sourcing of metals from mine waste.”
Decarbonising Steel
Various methods to decarbonise steel manufacturing include carbon nanotubes, hydrogen plasma and electrolysis.
The CSIRO and Swinburne University of Technology are partnering to tackle global decarbonisation with mineral processing research and development.
Keith Vining, CSIRO Carbon Steel Futures Research Group Leader, stated that to support decarbonisation efforts within the minerals industry, “we need new R&D partnerships that bring together complementary capabilities. We have partnered well with Swinburne for many years but have jointly decided the time is right to amplify our intent and efforts.”
One alternative method of decarbonising steel manufacturing is carbon nanotube and graphene technology, which have potential as greener steel replacements for various industrial and structural applications.
Another promising method for reducing emissions is using hydrogen plasma instead of carbon.
Molten oxide electrolysis, utilising renewable electricity, also offers a greener steel production method, decoupling steel from fossil fuels.
Our obsession with mining finite resources has left Australia in a deep hole in the transition to net zero by 2050.
Australia produces half the world’s iron ore, and turning ore into steel is energy-intensive, aggregating in 8% of all emissions – a hefty chunk of the climate pie.
Like a cat chasing its tail, we use vast amounts of carbon to extract finite metals for infrastructure and renewable energy, creating a linear emissions cycle requiring more mining and renewables.
As discussed, the steps toward circularity include decoupling the mining industry from fossil fuels and implementing eco-mining alternatives like recycling metals, phytomining, biomining and decarbonising steel.
Having ascended these eco-steps, let’s take our collective foot off the emissions pedal and be ‘ore’ inspired by the view of molten metal flowing mercurially through closed-loops as we transition to mining the sustainable future we deserve.