A new ironmaking process that offers a cleaner way to produce oxygen-free iron nuggets is moving from pilot testing to a demonstration stage at a Great Lakes mining plant. If the demonstration proves successful, it could lead to construction of the world's first, full-scale iron nugget production plant. The nuggets could be substituted for pig iron in the steelmaking process.

The ITmk3 Process, developed by Tokyo-based Kobe Steel and its subsidiary Midrex Technologies Inc., Charlotte, N.C., uses a rotary hearth furnace to convert iron ore fines and pulverized coal into iron nuggets of the same quality as blast furnace pig iron. Kobe first tested the process two years ago in Japan at a 3,000-tonne-per-year pilot plant. Midrex and a team of U.S. partners are now retrofitting a portion of a taconite plant in Silver Bay, Minn., to demonstrate the process at 25,000 tons per year.

"It's a technology well suited for the iron ores of Minnesota," says Larry Lehtinen, president of Silver Bay-based Mesabi Nugget, LLC, which is coordinating the $26-million demonstration project. Minnesota mines produce over half of the nation's taconite, a low-grade iron ore with high silica content. Minnesota ores normally are pelletized and shipped to blast furnaces where they are converted to pig iron, which can then be used to make steel. But the ITmk3 process will produce a pig-iron-grade material with the oxygen and silicates already removed, reducing weight and shipping costs by one-third, he says.

The rotary-hearth process also emits 20% less carbon dioxide than blast-furnace operations, says Chris Ravenscroft, a Midrex spokesman. Because of environmental concerns, "blast furnaces are being phased out, so the [Minnesota] iron range needs to find other uses for their product," he says.

Work started this summer to convert an existing 160-ft x 160-ft building into the demonstration plant. Mesabi is acting as owner and general contractor, with Midrex handling engineering. Lakehead Constructors Inc., Superior, Wis., demolished concrete foundations and floors to make way for a new layout to be built by Industrial Maintenance Service, Escanaba, Mich. Several other contracts will be let before the project is complete in early 2003.

Cleveland Cliffs, owner of the taconite plant operated by North Shore Mining Co., is helping fund the project, along with Kobe Steel, Fort Wayne, Ind.-based Steel Dynamics Inc., and the Minnesota state government. The U.S. Dept. of Energy is expected to fund half of the operational costs. After a one-year demonstration, the team will decide whether to build a $150-million-plus commercial-scale plant, says Lehtinen.