New technology for cleaner greener steel
Dr Alfonso Chinnici, from the University of Adelaide’s School of Electrical and Mechanical Engineering is leading a project through the Heavy Industry Low Carbon Transition (HILT) CRC to increase the quality of Australian iron ore, whilst reducing emissions.
Dr Alfonso Chinnici presents his work in emerging thermal pre-treatment technology at the 2024 HiTeMP-4 Forum.
Australia is the biggest iron ore exporter in the world and produces close to 1 billion tonnes of iron ore per year, particularly for markets like China, Japan and South Korea. But there are challenges faced by the industry, with much of the iron ore available today being of poor quality and not suitable for green steel production.
Traditionally steel has been made by melting iron ore in a blast furnace that uses fossil fuel as an energy source, creating a significant source of carbon emissions for the industry. Today a shift has begun to a greener pathway by using direct reduced iron (DRI) in an electric arc furnace (EAF) for making steel. The challenge with this pathway is that a high-quality feed stock is needed to make DRI, which requires high-quality iron ore.
“While Australia is still blessed with relatively high-grade material, the grades or our iron ore are declining because we have been mining iron for over 50 years,” says Dr Chinnici.
“Our minerals are changing in terms of their properties and their overall grade, that is, the iron content in our iron ore is reducing and the number of impurities, particularly silica, aluminium and phosphorus is increasing,” he explains.
Green steel making requires high grade iron ore, between 64 – 67% iron by mass, higher than Australia currently exports for use in blast furnaces, which can operate with an iron ore content between 58 – 62% iron: 62% iron by mass being the standard.
“We have been working, through the HILT CRC, on a novel beneficiation technology to clean and and upgrade Australian iron ore,” says Dr Chinnici.
Australia’s main region for mining iron ore is in the Pilbara in Western Australia. While iron ore sourced from other regions around the world responds well to traditional beneficiation, Pilbara ore, due to its complex mineralogy, does not.
“Because we have been mining for many years, the majority of our iron ore mines are below sea level and the ore is very sticky, with impurities locked together with the iron at the microscale,” Dr Chinnici says.
Dr Chinnici’s research is aimed at developing novel beneficiation technology to clean and upgrade the low-grade resource of iron ore in Australia, typically anything that contains less than 58% iron by mass. Currently, any material extracted from the ground less than 58% iron by mass is left there, as it can’t be sold to overseas markets.
We want to tap into the huge potential we have in Australia for low-grade iron ore as a source, to clean it and produce higher grade ore, using low-carbon, or ideally, net-zero carbon inputs and low water inputs.Dr Alfonso Chinnici, School of Electrical and Mechanical Engineering, The University of Adelaide & HILT CRC
His research team tested a series of iron ore samples, about 10 different types of iron ore from different areas of Australia that had different quality iron and mineralogy to ensure that the beneficiation technology was successful in upgrading the quality of ore regardless of the physical properties of the materials and were able to prove the success of the technology at lab scale.
The beneficiation technique used high flux radiation, a very fast form of heating, to heat treat the iron ore samples. Typically roasting of iron ore is a slow and inefficient process, whereby the material is roasted for hours in a rotary kiln, burning fossil fuels and creating carbon emissions. This flash heating technique allows the rock samples to heat up within minutes or seconds, using a renewable energy source to provide the radiation, reducing emissions, capital expenditure and operating cost.
Another benefit of using flash heating is the material being roasted undergoes thermal stress, any water trapped within the rock is released as steam and breaks the rock up as the steam is released, making the material easier to grind, which is the next step in the beneficiation process. Once the material is ground finely it is put through a magnetic separator and the impurities are separated out.
“Grinding is a very energy intensive process, very expensive, so by making the material more fragile, softening the material we able to demonstrate that we are able to save up to 30% of energy in the grinding step, to produce iron concentrates of above 60% when magnetically separated,” Dr Chinnici says.
The high flux radiation technique also makes the material more porous, which makes it more pliable for processing downstream for green steel making, through methods such as chemical leaching.
At lab-scale, Dr Chinnici’s team heated, ground and separated low grade iron ores, anything from 50 – 57% iron and were able to produce concentrates of above 60% iron. In certain conditions 64% iron by mass was achieved, which is a really high-grade iron that can be used to produce green steel.
To move the research out of the lab and to sub-pilot scale, Dr Chinnici has teamed with industry partner and machinery manufacturers, Magaldi Power, based in Salerno, Italy. Magaldi have invented a unique conveyor belt system that the team can use to experiment with bulk materials, rock materials in the sizes of milimeters or centimetres, with high through-put.
“Imagine this technology looks like a huge pizza oven and there are heaters, such as hydrogen burners on the top and the sides, and there is technology to recover the heat. Before you can grind the rocks you have to cool them down again”, Dr Chinnici explains.
Dr Chinnici has been working with Magaldi, to design a bespoke conveyor belt that could incorporate high flux radiation to roast iron, processing up to 2,000 tonne of iron ore per hour.
“So you can imagine that you take a low-grade iron ore resource, you treat it in this new UoA/Magaldi system, you grind and magnetically separate the ore and then this new material can be utilised to make DRI, which is the first step to produce green steel,” Dr Chinnici says.
This technology has been evaluated in 2 sub-projects within the HILT CRC, with a new flagship project about to commence, to move the research from producing high-quality green iron at lab-scale to sub-pilot scale. The research team are in discussions about how the next step to a pilot-scale demonstration may occur in future, to understand the technology more and maintain efficiency at large scale.
“In order to unlock green steel making for Australia, a pathway on how to cost effectively produce green iron needs to be identified. In addition, if reduced iron could be produced in Australia for export, rather than just shipping the raw material, there would be benefits in overall reduction of carbon emissions and increases in profit for the country,” Dr Chinnici says.
The work of Dr Chinnici and his team promises to ensure a positive future for the green steel making industry in Australia.
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Lead University of Adelaide Researchers: Dr Alfonso Chinnici (CI), Dr Woei Saw, Prof Gus Nathan, Prof Peter Ashman, Prof Nigel Cook Industry partners: HILT CRC, Fortescue Metals Group, Roy Hill, Liberty GFG, Grange, Magaldi, FCT Combustion and Calix Research organisation partners: HILT CRC, University of Adelaide, ANU, Victoria University of Wellington and Curtin University.
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Further reading
Current HILT CRC project:
Completed HILT CRC projects:
Green pyromet/hydromet beneficiation pathways