Limestone quarry still rockin’ after one year |

Limestone quarry still rockin’ after one year

Heidi Rice
Special to the Post Independent
Glenwood Springs, CO Colorado
Jury Jerome Post Independent

GLENWOOD SPRINGS, Colorado – It’s been nearly one year since CalX Minerals began producing limestone products after taking over the mothballed Mid-Continent Quarry in north Glenwood.

Mid-Continent opened the quarry in the mid-1980s to supply rock dust for its Coal Basin mines. Rock dust is powdered limestone that is applied to the walls and floor of an underground coal mine to control methane and prevent explosions.

When the Mid-Continent Coal Mine near Redstone shut down in 1991, the Glenwood Springs quarry remained mostly idle until 2008, when CalX Minerals bought it from the Delaney family.

“Between 2008 and 2009, we were mostly taking care of environmental aspects,” said Ben Miller, mine manager and an owner of the company. “The permits were still in place, but we expanded them.”

On July 12, 2010, the rock dust mill came online and CalX began shipping its products.

The mineral deposit at CalX quarry is the Leadville Limestone Formation, approximately 200 feet thick and composed of 98 percent calcium carbonate.

According to Miller, a graduate of the Colorado School of Mines, most chemical grade limestone deposits are closer to 95 percent calcium carbonate, so the Glenwood Springs quarry is a very high quality.

The limestone is blasted off the southfacing mountain, put into stock piles and stored in a silo. It is then transferred as needed into the mill where it is crushed and ground, packaged and loaded onto pallets for delivery. The process is done through an enclosed, computerized system typically run by three of the company’s 10 employees at any one time.

Of course, the whole operation is under the scrutiny of Miller’s dog, Houditch, who is hard at work with him every day.

The green-painted mill is hidden from view about two miles up Transfer Trail, cutting noise or view impacts to a minimum.

“The only place you can see the top of the mill from is from the Target parking lot,” Miller said. “And that means there are very few complaints,” he said, particularly from residents.

The quarry is capable of operating 24 hours a day, but bases its production on the demand.

“The mill can generally produce about 20 tons per hour,” said Justin Olin, mine superintendent. “And we use it all. Our principal is to create no waste.”

The pulverized limestone products have several uses:

• Rock dust in the coal industry

• To reduce soil acidity in agricultural operations

• As feed supplements for livestock and poultry

• In stack gas scrubbers used in coal and gas-fired power plants

• As an essential component in drilling mud

• As a manufacturing additive for glass, roofing materials, paper, paint and resins.

The company is also exploring sales of finely-ground limestone as hand chalk for rock climbers.

The majority of CalX Minerals customers are regional coal mines.

“There’s been a resurgence of coal mining in Colorado,” Miller said. “Mining is a lucrative industry that wasn’t really affected by the downturn.”

CalX has customers locally and throughout Colorado, Utah, New Mexico and the Four Corners area, he said.

More information about CalX Minerals is online at

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