Researchers from the University of Birmingham in the United Kingdom say they have designed an adaptation for existing iron and steel blast furnaces that could reduce carbon dioxide (CO2) emissions by nearly 90 percent.
Steelmakers around the world have been investing in different technologies to bring down the carbon footprint of the steel industry. In the United States, electric arc furnace (EAF) mill operators commonly point to their widespread use of ferrous scrap as an emissions reduction technique.
The Birmingham research involves a “closed loop” carbon recycling system for blast furnace/basic oxygen furnace operators. The university says the technique “could replace 90 percent of the coke typically used in current blast furnace/basic oxygen furnace systems and produces oxygen as a byproduct.”
The technique has been devised by Professor Yulong Ding and Dr. Harriet Kildahl from the University of Birmingham’s School of Chemical Engineering. The system has been detailed in a paper published in the Journal of Cleaner Production.
“Current proposals for decarbonizing the steel sector rely on phasing out existing plants and introducing electric arc furnaces powered by renewable electricity," Ding says. "However, an EAF plant can cost over $1 billion to build, which makes this switch economically unfeasible in the time remaining to meet the Paris Climate Agreement. The system we are proposing can be retrofitted to existing plants, which reduces the risk of stranded assets, and both the reduction in CO2, and the cost savings, are seen immediately.”
The university researchers refer to the blast furnace process as “inherently carbon intensive.” The carbon recycling system devised captures the CO2 from the top gas and reduces it to CO using a crystalline mineral lattice known as a “perovskite” material. The material was chosen as the reactions take place within a range of temperatures that can be powered by renewable energy sources and/or generated using heat exchangers connected to the blast furnaces, the researchers say.
Under a high concentration of CO2, the perovskite splits CO2 into oxygen, which is absorbed into the lattice, and CO, which is fed back into the blast furnace. The perovskite can be regenerated to its original form in a chemical reaction that takes place in a low oxygen environment. The oxygen produced can be used in the basic oxygen furnace to produce steel.
The University of Birmingham calls iron and steelmaking “the biggest emitter of CO2 of all foundation industrial sectors,” saying it accounts for 9 percent of global emissions. The university cites the International Renewable Energy Agency (IRENA) as saying the sector must achieve a 90 percent reduction in emissions by 2050 to limit global warming to rising by 1.5 degrees Celsius.
University of Birmingham Enterprise has filed a patent application covering the system and its use in metal production and is looking for long-term partners to participate in pilot studies and otherwise collaborate on further research to develop the system.
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