International expertise in low-emission steelmaking promises to help reduce the environmental impacts of Chinese industry.

Inside an electric arc furnace. Electric arc furnaces are replacing blast furnaces as a more environmentally friendly way of producing steel. In this image, a blue filter allows researchers to see the smelting.

Coal-guzzling blast furnaces that burn coke to smelt iron are a key reason steel production is a major emitter of greenhouse gases, responsiblefor around 7% of CO₂ emissions globally. Efforts to decarbonize steel production by reducing dependency on blast furnaces have gathered pace around the world. But China has been slow to adopt new, greener iron-smelting technology with90% of steel still produced using coal to produce coke.

Now, University of Science and Technology Beijing (USTB) metallurgist, Alberto Conejo, wants to speed up China’s transition. After spending decades specializing in a blast furnace alternative called the electric arc furnace (EAF) in his native Mexico, Conejo moved to China in 2018, as professor of metallurgy at USTB.

“The main challenge facing iron and steelmaking today without a doubt is pollution,” says Conejo.EAFs have the potential to slash China’s CO₂  emissions from steelmaking by up to 80%, he says.

The coal-derived coke used in traditional blast furnaces serves two main purposes. It burns at the high temperatures needed to smelt iron ore, and it acts as a reductant, deoxidizing the iron ore to produce iron. This dual purpose makes it particularly difficult to replace coal with electricity for iron smelting.

To help tackle that problem, working at the Morelia Technological Institute in Michoacán, Mexico, Conejo spentdecades developing EAFs for steelmaking. These use high-powered electrical arcs instead of coke to heat the furnace, a process that produces five times less CO2, says Conejo.

Conejo’s team in Mexico dived into the fundamentals of the formation of ‘foamy slag’ during the EAF process, further reducing energy consumption1,2. As iron is smelted, the hot molten iron mixture inside the furnace, or slag, produces gases, which generate a foam at its surface.

Conejo’s team developed a way to direct the foam to coat the high-powered electric arcs that heat the furnace. Left uncovered, the electric arcs lose heat energy through radiation. But a coating of slag foam “drastically lowers energy consumption,” says Conejo, who has designed slag foaming control systems to improve many steelmaking plants in Mexico.

Replacing coke’s second role as a reductant in steel production has proved tricker and is a key reason China has been slow to embrace EAFs. While 80% of Mexico’s steel is now made in cleaner EAFs, in China, the method produces just 10% of steel, partly because China lacks enough high quality steel scrap to feed the EAFs, Conejo explains.

In Mexico, most EAFs use unwanted steel scrap as a source of feedstock. But China does not produce much scrap, so Conejo hopes that an emerging feedstock called direct reduced iron, or sponge iron — which can be produced from iron ore and coke-oven gas generated from heating coal, which is plentiful in China — could help Chinese steelmakers adopt EAFs.

“The steel industry has made huge progress in the last 50 years. Using the best available technologies would facilitate the reduction of CO2emissions,” he says.

Metallurgist Alberto Conejo of the University of Science and Technology Beijing is helping Chinese industry embrace greener iron-smelting technology.

Conejo is now working with the Chinese steel industry on both the EAF and direct reduced iron technologies. In 2023, the second largest steelmaker in China, HBIS Group agreed to open their doors to USTB for collaboration, an exciting moment for Conejo. “This is something I wanted to do since I arrived here,” he says.

Conejo also hopes to connect Chinese steelmakers with other steel manufacturing experts from around the world, through organizations such as the Ferrous Metallurgy Research Institute or FeMRI, which provides global training, consulting and research services.

Meanwhile, Conejo continues to research ways to lower the environmental impacts of steel production while increasing steel quality. But the research methods he now uses have changed — today, metallurgical research can often be done with mathematical and computational techniques, sparing researchers from resource-consuming and sometimes dangerous experimental work, while creating opportunity to improve the 120-year-old EAF technology.

Whatever the approach, USTB is an ideal place for metallurgy research, says Conejo. “Based on the Shanghai Ranking, the metallurgy department is number one in the world. It has an excellent working atmosphere, with plenty of freedom. It is stimulating to be in a place where faculty members and students work very hard.”

Life in Beijing is also good, he says. “The people are kind. The culture is rich. There are many mountains to hike,” he says. “I enjoy my life here every day.”