Scientists are working hard on developing a way to decarbonise steel using Pilbara iron ores.
The focus on renewable technologies in mining could help Australia’s economy (and our zero-carbon energy transition) to flourish as the country looks to switch to green metals – steel, aluminium and other metals produced without fossil fuels.
Investing in iron
Australia is the world’s largest exporter of iron ore, responsible for roughly 55 per cent of global market share in 2024. Nearly all of this metal is from the Pilbara region in Western Australia, which is also the world’s largest exporter of alumina.
However, iron and steel production accounts for 6 to 8 per cent of global carbon dioxide emissions, while aluminium is responsible for another 2 per cent.
According to projections from the Superpower Institute, switching to “green” iron production using renewable energy could grow the country’s iron ore export earnings from $116 billion in 2025 to $386 billion by 2060.
But before this fossil-free production is possible, there are several challenges that experts need to overcome. The most complex of these challenges is the purity of Pilbara ore, which is around 55 to 62 per cent iron and not pure enough for current low-carbon and carbon-free technologies.
Resolving the purity problem
Iron ore from Pilbara contains silica and alumina, which reduces the ratio of iron content while increasing the ratio of gangue (waste rock and minerals). These impurities are bound to the iron oxide in the rock and can only be removed using high-temperature processing.
In order to remove oxygen and impurities from iron ore in the steelmaking process, it is typical to use coal in blast furnaces. This means there is a large amount of carbon dioxide released into the atmosphere.
More environmentally friendly direct reduction (DRI) options use gas or hydrogen to reduce impurities, however the iron ore content must be over 67 per cent to be effective and this excludes lower-grade Pilbara ore.
Instead of waiting for new technologies to emerge, which could take decades, the CSIRO is currently testing whether existing DRI technology can be enhanced to separate the elements of lower-grade ore.
CSIRO researchers are part of a cross-industry project to determine if DRI operations can be enhanced to include a broader range of materials.
Technological wonders
The main focus at the current stage of development is determining whether Pilbara ore can be adapted for new production processes. When the metal is heated, a structural change occurs and it becomes full of microscopic holes that weaken the material. In a shaft furnace, where the ore is weighed down by other materials, it could break apart.
Luckily, a recent study uncovered a promising method for making pellets to go into the shaft furnace. Researchers are also finding ways to remove unwanted material such as silica and alumina in the initial processing stage, so less ore needs to go through the energy-draining grinding stage. After grinding, classification systems have been enhanced to avoid recycling fine materials back through the technology.
The key to the classification stage is the hydrocyclone, which sorts particles at an industrial scale using water and centrifugal force.
While the hydrocyclone has lower accuracy than simpler methods, it can be scaled up for industry, and a commercialisation partner is now deploying it in operations.
The CSIRO is also building end-to-end pilot-scale capability to simulate the entire process of iron ore production. Coupled with an electric smelting furnace and existing pelletising equipment, successful tests could mean this technology is rolled out in the coming years.
To achieve the ambitious goal of net-zero iron ore production, a massive investment in infrastructure is required, including the construction of an industrial-scale renewables grid. Energy levels will need to drop to competitive levels, which is difficult when the Pilbara region is so remote. Most shipments in or out must go through Fremantle, before taking a 1300 kilometre journey by road.
Solving these problems is the first step towards a renewable future.
A greener future is in sight
Thankfully, there are several projects currently underway that are using reformed natural gas as a bridge fuel.
Gas reforming uses steam heated at 700 to 1000 degrees Celsius to turn methane into hydrogen and carbon monoxide. This process uses 50 per cent less CO2 than a blast furnace.
Importantly, new furnaces designed for gas-based reduction can easily switch from natural gas to renewable hydrogen to kickstart carbon-free iron production. Already, two major companies have announced plans to prepare hydrogen-ready DRI plants for three years of test operations.
Studies have shown that a technology called molten oxide Electrolysis (MOE), which was initially developed by NASA to manufacture iron on the moon using electricity, is another possible pathway for material processing. However, it has not been tested at a large scale.
If experts are able to overcome the current hurdles, Australia could be looking at significant economic benefits.
By ramping up iron production gradually, the country can expect a revenue of around $386 billion by 2060.
Moving away from fossil fuels would also shift Australia from an ore exporter to a value-added producer connecting renewable energy with overseas partners. By switching to green metals, the country could transform its environment and economy.
To read about what Victoria’s Twelve Apostles reveal about Australia’s environment, click here.