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January 19, 2004--When Michigan Technological University's Jiann-Yang (Jim) Hwang (pronounced "wong") wanted to try out a new idea for making steel, the first place he went was Wal-Mart.
Hwang, an associate professor of materials science and engineering and director of MTU's Institute of Materials Processing, picked up six microwave ovens at the local discount store and brought them back to his lab. He took them apart, wired the magnetrons together into one super-heavy-duty microwave, and added an electric arc furnace. Then he zapped a mixture of iron oxide and coal.
When he was done, he had a nugget of pure steel.
As gee-whiz as it is, Hwang's innovation is not just a high-end parlor trick. The microwave energy reduces the iron oxide to iron, and the electric arc furnace smelts the iron into steel, all in one device. The process may have the potential to revolutionize America's troubled steel industry, plagued as it is by high costs and foreign
The savings would come first in the form of lower energy costs. Just as a microwave oven use less electricity than a conventional oven because it heats only the food, microwave steelmaking uses less energy than a blast furnace because it heats only the ore and coal.
"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. Iron oxides can be heated to 1,000 degrees Celsius in one minute, compared to hours for conventional heating."
The electric arc furnace is currently used in state-of-the-art smelting processes and is more efficient than conventional oxygen furnaces used in most big plants to convert iron into steel.
In addition, the microwave steelmaking process is simple, with fewer than half the steps used in conventional steel manufacturing. And it uses coal, eliminating the need for high-cost coke.
Microwave technology's energy savings and manufacturing efficiency could cut production costs by as much as 50 percent, Hwang says. Plus, it's friendlier to the environment, since the process releases half the greenhouse gases (primarily carbon dioxide) of conventional steelmaking, and much less of the pollutant sulfur dioxide.
The new technology has the potential to breathe new life into U.S. heavy industry, particularly in the Great Lakes region, where the steel and auto industries are centered.
More than 30 steel mills have gone bankrupt in the last four years even with tariff protection. The resulting high domestic steel prices have hit American automakers hard, since they are forced to pay more for steel--the main ingredient of all cars and trucks--than their foreign competitors.
"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," Hwang said.
Hwang's research was funded by a grant from the U.S. Department of Energy.