Renewed interest in cement production in North Dakota

Associated Press
Published Sunday, March 12, 2006

BISMARCK - Fred Anderson carefully squeezes a drop of hydrochloric acid onto a piece of gray-white shale, setting off a bubbly, fizzy reaction. It means the rock may be suitable to make cement.

Anderson, a geologist who works for the North Dakota Geological Survey, says the reaction shows the rock contains calcium carbonate, a necessary ingredient for cement.

Geologists want to know if enough of the rock can be found in eastern North Dakota to run a profitable cement plant. It's a subject of intense interest in North Dakota's construction industry, which has seen the cost of cement rise sharply because of increased demand.

Greg McCormick, a spokesman for Northern Improvement, one of the region's largest highway construction companies, said the cost of cement has jumped from $100 a ton to about $125 a ton in the last few years.

During last year's construction season, North Dakota companies had trouble getting enough cement to meet their needs, McCormick said.

Ed Murphy, North Dakota's state geologist, said a North Dakota company is interested in building a limestone mine and cement plant in the Red River Valley, near a rock formation called the Niobrara. The Niobrara, which extends into South Dakota and other states, was formed while the land was still under water.

Most of North Dakota's cement now comes from Canada or Iowa, and a closer source may help lower cement prices in the area, Murphy said.

Anderson says rock that can be used to make cement contains many minerals, including calcium, silicon, aluminum and iron. Niobrara rock needs an additional source of calcium carbonate to make cement, he said.

Murphy said the unidentified company that is interested in North Dakota cement manufacturing plans to use urea pellets from animal waste, or carbon dioxide from North Dakota's power plants, to raise the calcium carbonate level in the mix.

In the cement-making process, different components are heated in a kiln, which creates new compounds, said John Melander, director of product standards and technology for the Portland Cement Association. The product is then ground into a fine powder, which hardens when combined with water.

It is not unusual for cement plants to bring in outside materials to supplement their mix, Melander said. Some must import silica sand or iron. Companies must figure out whether they can ship in material and still sell their cement at a profit, he said.

"In reality, it's very seldom that a plant is having what is sometimes classified as a cement rock that has the mix of chemistry that you need to (naturally) produce a Portland cement," he said.

Portland cement is a high-quality cement used in construction. Patti Flesher, an association spokeswoman, said 2005 was the third consecutive year of record cement use in the United States.

Many North Dakota construction and concrete companies get their cement from LaFarge Dakota Inc., a unit of LaFarge North America Inc. of Herndon, Va.

Paul Chale, LaFarge Dakota's general manager, said the company should be able to supply its customers with enough cement this year. Last year, LaFarge Dakota had to limit the amount of cement customers could buy, he said.

Cement producers have tried before to use North Dakota shale to make cement, Murphy said. The state's first cement operation was in the Cavalier County town of Concrete, in the 1890s and early 1900s.

Rocks used at the plant were less than 70 percent calcium carbonate, and it takes 80 percent calcium carbonate to make Portland cement, Anderson said. The company marketed its product as natural cement, but it could not compete and was eventually shut down.

The LeHigh Cement Co. explored putting a cement company in North Dakota in the 1960s. LeHigh decided the shale's calcium carbonate level was too low, and it would be too costly to add outside sources of limestone to meet Portland cement standards, Anderson said.

"We've done a lot of investigative work over the years, but there's so much more we could do," he said. "Typically, the industry drives that need."