With a manufacturing process responsible for 7 percent of the world’s carbon-dioxide emissions, concrete often gets a bad rap. But steel, frankly, is no better. Steel production is the second-largest industrial consumer of energy.
To improve steel’s track record in this area, researchers at the University of Utah have developed a flash-forming reduction technique that produces iron—the primary component of steel—in a more efficient manner. Typically, liquid iron is smelted from a mixture of iron ore, limestone, and coke (a high-carbon fuel made from coal) in a blast furnace, requiring a lot of heat and forced air. Instead of using coke, the Utah researchers’ flash iron-making process uses hydrogen or natural gas to extract the iron particles through reduction. “These gases?…?have a greater affinity to oxygen than iron,” says Hong Yong Sohn, a professor of metallurgical engineering and an adjunct professor of chemical engineering at the university. “Thus, they remove oxygen from iron oxide in iron ore, leaving iron in the metallic state.”
This approach can leverage the large quantity of iron ore concentrate—particles smaller than 0.1 millimeter—that is produced in the United States and other countries, and bypass the intermediate step of forming the particles into ½-inch pellets before ironmaking. Steel producers could streamline the process further by making steel in the same vessel as the molten iron and foregoing the blast furnace altogether.
The technology, which may require another three to five years to reach commercialization, would slash the energy requirements needed to make iron by half, Sohn says. It would also emit only 0.04 metric tons of CO2 per metric ton of iron—a 97.5 percent improvement over using the conventional blast furnace.
Note: This article expounds on the Dec. 26, 2013, Mind & Matter post. Blaine Brownell, AIA, is a regularly featured columnist whose stories appear on this website each week. His views and conclusions are not necessarily those of ARCHITECT magazine nor of the American Institute of Architects.