A new, integrated low-emission steelmaking process could improve the prospects of the Australian steel industry by increasing productivity and slashing carbon dioxide emissions, water and energy use around the world.
Traditional steelmaking is energy-intensive
The Australian iron and steel industry produces about six million tonnes of steel and 14 million tonnes of greenhouse gases (mostly carbon dioxide) a year. This is about 2.5 per cent of Australia’s total annual emissions.
Most of the iron and steel industry’s emissions occur during production of iron in the blast furnace, where coal and coke are used as fuel and as a reducing agent.
The steelmaking process also creates large volumes of slag, a stony waste material. A plant producing one million tonnes of steel a year also produces 300,000 tonnes of slag and globally this amounts to hundreds of millions of tonnes of slag each year.
The Australian steel industry is seeking ways to work smarter and sustainably by lowering its energy and water use, carbon dioxide emissions and waste.
Integrating two new technologies
Working with industry partners BlueScope Steel and Arrium, we have developed a low-emission integrated steelmaking process based on two technologies.
Using charcoal to replace a portion of the coal and coke used in steelmaking is the first way to significantly reduce carbon dioxide emissions without substantially modifying the steelworks. An innovative technique to produce charcoal has been developed and produces ‘designer biochar’ which can be made to meet the demands of eight potential applications involved in steelmaking.
Secondly, we have developed a new ‘dry’ method for granulating slag. It allows waste heat to be captured and used onsite for drying, preheating or steam and electricity generation. Dry granulation saves a significant amount of water when compared to ‘wet’ granulation methods.
Halving emissions and slashing water use
Together, the technologies would save about 24 petajoules of energy, reduce greenhouse gas emissions by about 100 million tonnes, and save up to 25 gigalitres of water for the world’s steel industry each year, with just 10 per cent of global market penetration.
The processes produce valuable by-products and enable the industry to make ‘carbon lite’ steel, differentiating it from other producers including low-cost importers.
Assuming 10 per cent market penetration by 2030, these technologies have a potential risk-adjusted net present value of $22 billion.
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