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Bentonite booms in Wyoming, Montana

Geologist Gretchen Hurley with the Bureau of Land Management walks through a bentonite bed east of Greybull, Wyo., in May. (Associated Press)
Geologist Gretchen Hurley with the Bureau of Land Management walks through a bentonite bed east of Greybull, Wyo., in May. (Associated Press)

GREYBULL, Wyo. – Applications to mine “the clay of 1,000 uses” are pouring into the Bureau of Land Management as companies look to capitalize on the bentonite boom and keep pace with the nation’s economic rebound.

From mines at Frannie, Wyo., to Bearcreek, Mont., companies have ramped up production, racing to extract a commodity that was deposited millions of years ago as volcanic ash and chemically reworked in a shallow, inland seaway.

At M-I Swaco’s mine east of Greybull, Wyo., BLM geologist Gretchen Hurley holds a lump of bentonite in her hand. With the consistency of Play-Doh, the damp product is easily shaped, rolled and squeezed.

“I think the new applications are a result of companies trying to get ahead of the permitting curve, because it takes a while to permit one of these mines,” Hurley said. “If we can get them approved for a 500-acre mine, that’ll keep them supplied in bentonite for 10 to 30 years.”

Bentonite has the ability to swell to 16 times its original size and absorb 10 times its weight in water. It’s used in cat litter and beauty supplies and as a binding agent in animal feed. It’s also used in foundry work and in oil drilling.

The clay’s industrial uses tie it directly to the nation’s energy and auto industries. With the economy slowly on the mend, the bentonite industry has followed suit, restoring jobs lost in 2008 while creating an increase in mining applications across the region.

At the American Colloid plant east of Lovell, Wyo., plant manager Steve Wilkerson said that at the height of the recession, around 42 employees lost their jobs. Around 30 of those jobs have been restored and production has increased, surpassing pre-recession figures.

“Before the recession we were running at around 650,000 to 700,000 tons a year,” Wilkerson told the Billings Gazette. “In 2008, we dropped off to around 280,000 tons. At the present moment, the way things are going right now, we should be back at around 750,000 to 780,000 tons.”

The life of a bentonite mine depends on market conditions, and it’s Lyndon Bucher’s job at American Colloid to ensure that a steady flow of clay is available to keep pace with customer demands, including the oil industry, General Motors and Caterpillar.

Bucher, who works in American Colloid’s permitting and reclamation department, said that like all mining operations, clay is subject to booms and busts. Business lately has been up.

“Bentonite is considered an industrial mineral, and so it goes into a number of different products,” Bucher said. “You could say we’re something of a bellwether for the national economy. For the most part, as the economy goes, so goes the bentonite industry.”

Wyoming’s annual bentonite production has risen from 1,400 tons in 1927 to more than 4.5 million tons. Five companies are engaged in 19 active mining plans across several counties in Montana and Wyoming, according to the BLM.

“I’m supposed to maintain at least five years of permitted reserves in every grade of bentonite,” Bucher said. “We’ll do the exploration drilling to locate and grade the product. Once the exploration is done, we know where we need to permit.”

This arid region of the basin, which extends down the western front of the Pryor and Bighorn mountains in Montana and Wyoming, is considered one of the world’s top producers of high-swelling, sodium-type bentonite clay, representing nearly 70 percent of the world’s known supply.

It wasn’t until 1888 that the first commercial shipment of bentonite was made. The clay earned its name from discoveries in Montana’s Fort Benton Formation. It’s been sought after ever since.

On the hood of her truck, Hurley lays out a map with the mines designated in red. The bentonite sought by companies lies in a north-south trend along the eastern rim of the basin.

Hurley said an inland sea once covered this region while mountain-building volcanoes to the west spewed ash. The ash settled into the sea, where it was chemically worked over time.

Buried by sand, pressurized and compressed, it became the product rolling by the ton into the basin’s plants. There, it’s dried, processed and packaged in powder and granular forms to meet customer needs.

“There are several different beds, and each bed has its own unique properties,” said Jason Schneider, the mining operations manager with American Colloid. “We’re trying to select different beds to meet the demands for the final product.”

Standing at a cross-cut at the Frannie mine on the state line, Schneider notes the striated layers of shale and the bed of bentonite below. Even here in this small pit, no more than an acre in size, the bentonite comes in yellow and blue.

Schneider said each bed of clay is given to a different set of qualities suited for a variety of industrial uses. It’s up to the companies to extract and process the right clay for the job.

“For this location, it’s a lot of drilling mud,” Schneider said. “With the activity in North Dakota, in the Bakken, that increases the demand for drilling mud. Foundry work has been real strong as well – the auto market. Those things are coming back, and when the economy starts to pick up, you see it on this end.”

Estimates vary on how much accessible bentonite remains here in the ground. A 1989 report by the American Institute of Mining Engineers suggests that around 1.1 billion tons have yet to be mined.

A 1980 edition of the U.S. Bureau of Mines, Minerals, Facts and Problems lists bentonite reserves of around 200 million tons. Either way, it’s enough to keep the bentonite industry supplied for years to come.

“If it’s oil and gas drilling, we’ll target a specific clay for that, and if it’s cat litter, we’ll target another clay for that,” Bucher said. “We have many different customers, and we’ll try to meet the market demand by mining in these different areas and getting the right quality of clay into the plant.”


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