Microwave Steel: Faster, Cleaner, Cheaper

Newswise — The same couch-potato technology that pops your popcorn during a TV commercial can now be used to make steel.

You shouldn't try it at home, however, since it involves heating the raw materials up to 1,000 degrees Celsius, about the same temperature as molten lava.

The feat was accomplished by Michigan Tech researcher Jiann-Yang (Jim) Hwang, who wired together the magnetrons from six garden-variety microwaves into one super-heavy-duty oven and added an electric arc furnace. He then put iron oxide and coal inside. In a matter of minutes, the microwave energy reduced the iron ore to iron, and the electric arc furnace smelted the iron and coal into steel.

The process could give the steel industry the same benefits that a microwave gives the typical family, says Hwang, an associate professor of materials science and engineering and director of Michigan Tech's Institute of Materials Processing.

It's really cheap, and it's really fast.

"With a blast furnace, most of the heat escapes," Hwang says. "It's like the stove in your home, where most of the heat warms your kitchen. It's inefficient. In our microwave, iron oxides can be heated to 1,000 degrees Celsius in one minute, compared to hours for conventional heating."

Microwave technology could cut production costs by as much as 50 percent, Hwang says. In addition to energy savings, it uses coal, eliminating the need for high-cost coke. And the manufacturing process is simple, cutting the number of steelmaking steps in half.

It's also friendlier to the environment, with significant reductions in greenhouse gases and sulfur dioxide emissions.

Industry officials aren't ready to throw their existing technology out the window just yet, but they are taking a close look at the Hwang's invention.

"This could be a promising technology, particularly for helping us reuse byproducts that are currently being discarded," said Mark Conedera, a senior environmental engineer with US Steel Corporation. "We've been supportive of the concept for these value-added uses, and it has significant environmental benefits."

Hwang believes his new technology has the potential to benefit U.S. heavy industry, particularly in the Great Lakes region, where the steel and auto industries are centered.

"A low-cost steelmaking technology would take advantage of U.S. iron and coal resources and could help keep manufacturing jobs in Michigan and throughout the Great Lakes," he said.

Hwang's microwave steelmaking research was supported by a grant from the U.S. Department of Energy.