Building trades workers and prime contractor Jamar performed a significant amount of maintenance work and pollution control upgrades over the last several months in an effort to further clear the air at the Cliffs Michigan Mining Company's Tilden (West) operation, west of Marquette.

Their efforts were focused on the two coal/gas burning units at the Tilden plant's iron ore pelletizing operation. Following back-to-back three-week shutdowns, Unit One was repaired and placed back into operation in February, and work on Unit Two was complete at the end of March.

"The primary objective was to upgrade the efficiency of the precipitators in both units," said Gary Hedberg, mechanical engineer at the plant for Cliffs Michigan Mining. "We met our objectives on both. We performed extensive work on both units, but the work was different."

On Unit One, the trades' primary task was installation of 105 tons of new carbon steel ductwork, which replaced a fair amount of corroded ductwork. Unit Two received a precipitator conversion rebuild.

The precipitator work will further reduce the volume of particulate from the exhaust stream during the operation of the pelletizing plant. The work will help bring the Tilden plant pelletizing units in line with more stringent federal clean air standards that will soon go into effect. The precipitator upgrades were some of the most extensive work the plant has seen since Unit One was placed in operation in 1973, and Unit Two came online in 1977.

"Work on both units went well," said Cory Bushong, project manager for Jamar, "We made the customer happy, and that's what's important."

The Tilden plant's final product is about 8 million long-tons per year of iron ore pellets, which are shipped to steel mills. Before the ore is formed into the marble-sized pellets, the iron has to be taken from the earth, crushed and separated from waste material. Rotary kilns on each pelletizing unit heat the iron to 2,400 degrees to harden the material into pellets.

Hedberg said Units 1 and 2 run concurrently 24 hours a day until they are individually taken down, usually during the first quarter of the year, for repairs and maintenance. "Normal for us is operating both units at full capacity," he said. "We keep them in good repair throughout the year, but these shutdowns are necessary for major work. Overall for this work the workers and the contractor have done a good job."

Setting up a section of ductwork for placement are Rick and Cal Jenerou of Boilermakers Local 169 and Jamar, working at the Cliffs Michigan Tilden Mine. Photo by Jeff Zdebski