Mesabi Nugget LLC in recent
years began production of a marble-sized iron pellet that
observers call the most revolutionary new iron-making process
in half a century.
"The Mesabi nugget is a really,
really nifty product," said Peter Kakela, professor of resource
development at Michigan State University in East Lansing.
"Larry Lehtinen, who spearheaded the project, always said that
the second most exported commodity from Minnesota is the oxygen
that is locked up in the iron ore pellets. The iron nugget
project simply takes the oxygen out of the pellet."
Fort Wayne, Ind.-based Steel
Dynamics Inc. (SDI), parent of Mesabi Nugget, partnered with
Japanese steelmaker Kobe Steel Ltd. to pioneer the worlds
first commercial-scale iron nugget operation. The $275-million
facility at Hoyt Lakes, on the east end of Minnesotas
Mesabi Iron Range, uses Kobe Steels patented ITmk3
ironmaking process to convert "dry balls" of iron fines,
pulverized coal, fluxes and binders into 3⁄8-inch iron
nuggets using a direct-reduction process in a natural-gas-fired
rotary hearth furnace. The pellets are 96- to 98-percent pure
iron, with the remainder primarily carbon.
"Weve gone from 65-percent
iron with taconite pellets to 97-percent iron with Mesabi
nuggets," Kakela said. "They are able to make steel cheaper and
cleaner with the nuggets. They are shipping a higher-quality
product that can go into the EF (electric-arc furnace) at the
mini-mill as well as into the blast furnace."
Kakela noted that the gain in
sustainability with commercial-grade iron nuggets is equal to
the gains made half a century ago when the steel industry
adopted a pioneer taconite processing technology in the Lake
Superior iron ore fields. For most of the late 19th and early
20th Centuries, the industry had shipped several billion tons
of rich, red natural hematite ore to the open hearth and blast
furnaces that stretched from Chicago to Pittsburgh. By the
1950s, however, the industry was worried about the depletion of
the Minnesota and Michigan iron ranges. Work done at the
University of Minnesota by Edward W. Davis introduced a method
of processing taconite, a plentiful low-grade ore that had
never been utilized in the domestic steel industry. From the
late 1950s to the early 1970s, the industry spent billions of
dollars to build taconite pelletizing facilities in Minnesota
"It was the salvation of the
U.S. iron industry," Kakela said. "The pellets used a little
more energy at the mines but they more than overcompensated on
the blast furnace side."