University of Toronto Develops Breakthrough Steel Recycling Method to Cut Carbon Emissions

University of Toronto researchers introduce a pioneering way to recycle steel that could revolutionize the industry and help achieve global net-zero emission goals.

Researchers at the University of Toronto have made a groundbreaking advance in steel recycling that promises to substantially cut down the steel industry’s carbon emissions. Their innovative method, detailed in a new paper published in Resources, Conservation & Recycling, aims to revolutionize how steel is recycled, potentially paving the way for a more sustainable and circular steel economy.

Led by Gisele Azimi, a professor in the Department of Materials Science & Engineering, the team developed an electrochemical process that removes impurities such as copper and carbon from molten steel, producing liquid iron and sulfur as by-products.

“Our study is the first reported instance of electrochemically removing copper from steel and reducing impurities to below alloy level,” Azimi said in a news release.

The implications of this work are significant. Currently, only a quarter of the world’s steel is recycled, and the demand for greener steel continues to rise as countries strive to meet their net-zero emission targets. Traditional steel production, which involves reacting iron ore with coke and blowing oxygen through the metal, is a major carbon emission contributor, releasing almost two tons of CO2 for every ton of steel produced.

Conventional recycling methods rely on electric arc furnaces to melt scrap steel, which often contains copper impurities that degrade the quality of the recycled steel. This restricts recycled steel’s use to lower-grade products, like construction rebar.

“The concentration of copper adds up as you add more scrap metals to be recycled, and when it goes above 0.1 weight percentage (wt%) in the final steel product, it will be detrimental to the properties of steel,” added Azimi.

The team’s novel technique employs an electrochemical cell, capable of withstanding temperatures up to 1600 degrees Celsius, that uses a slag-based oxysulfide electrolyte to remove copper and other impurities. This process can produce high-quality steel suitable for advanced applications in the automotive and transport sectors.

“Our method can expand the secondary steel market into different industries,” said Jaesuk (Jay) Paeng, a doctoral candidate and co-author of the study.

The innovative process not only promises higher-grade recycled steel but also offers a way to make the steel industry more sustainable by utilizing a common waste product — slag — as part of the recycling process.

In collaboration with Tenova Goodfellow Inc., a global provider of technologies for the metals and mining sectors, the team is now looking to refine their method further, aiming to eliminate other metal contaminants such as tin.

“Iron and steel are the most widely used metals in the industry, and I think the production rate is as high as 1.9 billion tonnes per year,” Azimi said. “Our method has great potential to offer the steelmaking industry a practical and easily implementable way to recycle steel to produce more of the demand for high-grade steel globally.”

This breakthrough could herald a new era for the steel industry, reducing its carbon footprint and contributing significantly to global sustainability efforts.