Steel is the world’s most widely recycled material, but its high embodied energy is roughly equivalent to that of concrete. A new method to extract iron from virgin resources might give the metal alloy the environmental edge after all.
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.”
Read more of Blaine Brownell’s article “Iron Man” in Architect magazine.