Holcim Inc has agreed to limit the amount of slag it uses from Asarco’s idled East Helena, Montana, plant — and will not use any more slag from a Canadian smelter — after tests from the state showed "a slew" of heavy metals in the slag. Holcim, which operates a cement plant near Three Forks, will voluntarily limit the amount of Asarco slag it uses to 15,000 tons per year, Richard Opper, director of the state Department of Environmental Quality, said on Friday. Last year, the company used about 10,000 tons.
"Tests showed arsenic, cadmium, mercury, zinc — a slew of heavy metals — in the slag that could pose a health risk," Opper said. "We need to know what’s coming out of the stacks … and we definitely will be monitoring their emissions." The DEQ determined that 15,000 tons per year meets "negligible risk standards" for the protection of human health and the environment.
Ash Grove in Montana City has utilized Asarco slag in its cement manufacturing process for about 30 years. Last year, the company used about 18,000 tons of Asarco slag, according to plant manager Dick Johnson.
The state may be able to regulate Holcim’s use of slag because it only recently started using it. But the Montana City cement plant’s use is allowed without the type of regulations like Holcim because of Ash Grove’s long-term use of Asarco’s slag. Still, Anne Hedges with the Montana Environmental Information Center believes neither plant should use any of the slag until the emissions, and not just the slag, are tested.
Nicole Prokop, alternative material manager for Holcim, said the company would like a little more flexibility in the amount of slag it can use. But she added that what’s more important than the makeup of the slag is what is emitted through the smokestacks, and emission tests by Holcim show only an increase in nickel. "We want to protect the public’s health and environment and operate safely, and are committed to doing things the right way," Prokop said. "We know what comes out of our stacks."
Prokop also said that she’s pleased Holcim and the DEQ have reached an agreement over the use of slag so that the DEQ can resume work on an Environmental Impact Statement, assessing the plan by Holcim to old burn tires as kiln fuel at the cement plant. "We’re hoping that the EIS can move forward," Prokop said. "They put it on the shelf until the slag issue was resolved." Helena (Montana) Independent.