Laying the foundation for cement production

Kiln: Company hopes expansion will make it the continent's premier maker of the concrete component.

March 19, 2001|By Sheridan Lyons | Sheridan Lyons,SUN STAFF

It looks like a science-fiction set, with a geodesic dome the size of a football field and a strange tower rising nearby. At this site, on the edge of the tiny town of Union Bridge, Lehigh Portland Cement Co. is assembling a state-of-the-art cement kiln.

When the house-sized sections of the kiln paraded slowly from Baltimore last year, people lined the streets to see them. Now the seven sections of Spanish steel are being welded into one 265-foot tube. When completed, the kiln is expected to double the amount of cement manufactured at the plant and, as a result, become the largest-producing single kiln in North America.

"Construction's just buzzing along," said David H. Roush, manager of the Lehigh plant on Main Street in Union Bridge. "It will be the most modern cement kiln anywhere - not the biggest, but the most modern. We'll also expand our customer base [because] we'll make twice as much."

The kiln is expected to be operating by September, part of a $265 million plant expansion that will continue into fall 2002, he said. Lehigh's expansion was undertaken to meet a demand for cement so high that the company has had to import some in recent years.

The kiln plays a central role in cement making: It bakes the basic ingredients at thousands of degrees Fahrenheit until physical and chemical changes transform them into cement.

Cement, when mixed with water and sand, becomes concrete.

Limestone quarried at the site is pulverized and stirred to minimize variations in the rock from layer to layer, resulting in a powder finer than sand but not as fine as cement, Roush said. Sand, ash and a dash of mill scale - concentrated iron flakes - are added before baking.

The 126-foot-high geodesic dome at the site, called a stacker, holds about 50,000 tons of crushed limestone - a week's supply for the Union Bridge plant, he said.

Near the dome, a 460-foot tower is about three-quarters built. Here, the raw mixture is heated to about 2,000 degrees, Roush said. Then, it will go to the new kiln, which will blast it with temperatures of about 3,000 degrees.

This pre-heater tower is the real star of the new operation, Roush said. Because of it, one shorter, wider kiln will replace the existing four, three dating from 1957 and one from 1971. Put another way, he said, the tower will do in 1 1/2 minutes what takes an old kiln 1 1/2 hours to do.

The finished cement is stored in silos, where trucks and train cars can pull underneath to load up.

Raw materials - sand, ash and mill scale - come in by truck, except the coal to fire the kiln, which comes by rail, he said. Most of the finished cement goes out by truck, with 25 percent to 30 percent by rail - a percentage that will increase.

Trains carry the cement from Union Bridge to company terminals in Baltimore and Norfolk, Va., where ships carry it overseas. "We ship out about a million tons a year now," Roush said, with trucks and trains carrying the cement primarily to Baltimore, Washington and Northern Virginia.

"We'll be able to sell 50 percent more right away," he said, "and eventually 2 million tons a year."

Because Lehigh has sold more cement than the plant can make the past few years, about 30 percent of its supply has been purchased overseas, mainly from Greece, Roush said.

"That is a major factor in our expansion," he said.

Maryland and Carroll County plan to build a road and rail spur to divert truck and train traffic from the town's Main Street. An additional 100 trucks are expected to leave the plant each day.

The Union Bridge plant started producing cement in 1910 as Tidewater Portland Co., which was acquired in 1925 by Lehigh and became its largest plant in the United States. Lehigh, whose headquarters are in Allentown, Pa., later became a subsidiary of Heidelberger Zement AG of Germany.

Union Bridge has provided cement for numerous area projects, including both of Baltimore's new stadiums and the replacement of the four 16-ton concrete lions at the William Howard Taft Bridge in Washington.

Although two plants in western Canada claim the biggest North American cement production, Roush said, "Next year, we'll be reclaiming it with a vengeance: We will have the largest-capacity kiln in North America."

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