Old Tires Help Produce Cement
PENROSE, Colo. Old tires -- lots and lots of old tires -- will help cement-giant Holcim cut its reliance on coal by 10 percent this year.
In 2005, the company will roll through 25,000 tons of tires -- 2.5 million tires -- to achieve the goal, managers say. The U.S. Environmental Protection Agency allows Holcim to burn up to 55,000 tons of tires per year.
The remaining 90 percent of the plant's fuel will come from 180,000 tons of coal.
The cement plant's kiln gets hot enough that the tires burn cleaner than most people think, Holcim plant manager Rob Davies said. "It is so hot the tires effectively evaporate," Davies said.
"You've seen a garden bonfire with tires where there is a lot of black smoke and fumes. But at 2,000 degrees, the tires we use evaporate and there is no smoke or fumes."
The plant burns up to one ton of tires per hour.
Not all of the process is invisible.
Unlike past years, the company is now stockpiling tires at the plant, a scene visible from U.S. 50 just east of Penrose. The stockpiling is a recent practice due to a change of contracts among tire suppliers, Davies said.
"We have had to accumulate the tires and stockpile them on-site so we would not run out," Davies said.
"We will start this month to use the stockpile and it should disappear as we deplete that inventory over the next 10 to 12 months," he said.
In the past, the plant received chipped tires from a Denver landfill.
Holcim's new supplier provides whole tires.
Employees will begin chipping the tires on-site later this month.
Chipped tires make up 10 percent of the fuel -- ground coal the remaining 90 percent -- to get the kiln up to 2,000 degrees so it can melt a powdered limestone mixture into clinker.
The clinker is then cooled and ground into the powder that cement customers buy at local hardware stores.
This year, the plant will use roughly 2.5 million tires to fuel the kiln around the clock. "The EPA estimates one resident produces one scrap tire a year.
"And with 4.5 million people in Colorado, we could burn all the scrap tires in the state plus then some. But not all the tires in the state find their way here," Davies said.
Holcim Technical Manager Richard Roush, who oversees the ongoing construction of the tire chipper, said he hopes to arrange a community service day for local residents to drop off their scrap tires at the plant.
To guard against tire fires at the stockpile, the scrap tires are placed in small piles with fire brick between them to prevent spread of fire should one pile go up in flames, managers say.
The tires also are sprayed with insecticide to prevent mosquitoes from breeding in water collected in the tires. So far the weather has been hot enough that the water is evaporating and not accumulating in the tires Davies said.
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Source: Knight Ridder/Tribune Business News