UNION BRIDGE - Lehigh Portland Cement Co. is awaiting state approval to burn lumps of carbon waste in its cement-making kilns here and could safely and efficiently burn other kinds of industrial waste, said the plant's manager.
"We believe a cement kiln is a particularly good place to burn waste materials," said manager David H. Roush.
Kiln temperatures of 2,700 to 3,000 degrees Fahrenheit burn more efficiently than standard incinerators at 1,700 degrees, he said.
An air quality and engineering review by the state Department of the Environment found the carbon lumps are similar to coal and would cause no significant changes in the environment or in human health, said John Goheen, a spokesman for the department.
However, the state will give the public an opportunity to seek a hearing before granting Lehigh's request, Goheen said. He said Lehigh will publish a notice in the next week in area newspapers alerting citizens they may request a hearing.
Cement plants around the country have begun burning waste, such as tires, compressed household garbage, sludge and hazardous waste, Roush said.
Lehigh now burns primarily coal, mixed with about 5 percent waste oil and less than 1 percent waste wood chips, Roush said. By mixing waste materials in with the coal, the plant hopes to save money on fuel, he said.
Other industries pay Lehigh to take their waste materials, but Roush said that money doesn't cover the overhead costs of things such as testing each batch to make sure it is safe to burn and meets state regulations. But the amount Lehigh spends on burning waste is still less than for coal, he said.
The "spent" carbon Lehigh wants to start burning will have had an earlier life as activated carbon at CEBA-Giegy, a plastics and dye manufacturer in New Jersey. That factory uses activated carbon to filter hazardous materials and solvents from water used in manufacturing before the water is discharged into the environment, Roush said. The carbon does not absorb the hazardous material, Roush said.
After the carbon burns in a kiln, any ash left over falls into the cement powder and becomes a part of the raw material Lehigh is manufacturing, Roush said.
"Everybody agrees this is not a hazardous material. It's no more dangerous than coal," Roush said.
"It could be landfilled, but lots of municipal landfills refuse bulky industrial waste" because they don't want to run out of space for household garbage, Roush said. "CEBA produces several tons a day, and they need somewhere to put it."
Even though the spent carbon is not a hazardous waste, Lehigh needs approval from the Department of the Environment to make any changes in what it burns, Goheen said.
The spent carbon would become about 1 percent to 2 percent of Lehigh's fuel mix, Roush said. It takes 4 pounds of the spent carbon to equal the heating value of 1 pound of coal, he said.
To make sure employees understand the proposed change, Roush said, he has begun meeting with them in groups.
By burning waste, cement plants can use materials that otherwise would take up precious landfill space. Although Lehigh is looking into using other kinds of waste, plans so far don't include burning anything that is now filling up Carroll landfills, Roush said.
Although the plant could burn most of Carroll's household plastic and paper trash, and possibly tires if a new kiln is built, no such plans are on the table now, he said.
James E. Slater, director of the Carroll Department of Natural Resources Protection, said he and his staff are looking at a number of options for reducing the amount of trash that has to buried but have not talked with Lehigh.