Most people probably don't think of cornrich Iowa as coal country. Compared with such top producers as Pennsylvania and West Virginia, or even neighboring Illinois, it is not.Its half dozen mines produced only a tiny fraction of the 740 millions tons of coal extracted in the United States last year.
But Iowa has coal country potential. Coal deposits underlie as much as-one-third of the state. And important fossil fuel research quietly under way here at Iowa State University has far reaching implications.
One of the major obstacles to more extensive mining of Midwestern coal is its high sulfur content. While some industry proponents have sought relaxation of emissions standards in the 1970 Clean Air Act, researchers involved in the univeritsy's Iowa Coal Project at Ames Laboratory have developed a sophisticated but economical liquid gravitation system that separates heavier, sulfur-laden pyrite from the lighter weight, purer coal before the coal is burned.
Convinced by a nearby demonstration project, Iowa's commercial mines last summer built two similar coal-cleaning plants to do the same "washing" job for them.
"The coal-producing industry in this state had been about to disappear because they weren't able to sell the product without cleaning it," observes Dave Birlingmair, hea d coal preparation engineer at Ames Laboratory.
The project up to now has been financed solely by state energy funds. But now the US Department of Energy has added its support to the project.
Researchers at Ames also are taking a harder look at the crystal structure of coal in the interest of extracting even more sulfur. Some of the sulfur organically bonded to the coal's skeletal structure has long been considered physically impossible to remove.
"We haven't figured a way other than cleaning to get sulfur out cheaply, but we think it may be possible," explains Mr. Birlingmair.
In addition, project researchers at the university's Energy and Mineral Resources Research Institute the trying to find economic ways to make coal dust available to power plants for burning and to cull out valuable mineral oxides from fly ash, a byproduct of the burning that normally is considered waste and buried in landfill. Ames researchers point out that typically 25 percent of the fly ash residue is alumina.
They say the process they are developing, which can also cull out iron, calcium silicate used in cement, and titanium, can remove alumina more cheaply than it can be taken from bauxite ore.
The search is on, too, for new ways to transport and use increasingly common, finely ground coal. The university lab has patented a process it developed for treating powdered coal with acetone to form weather resistant pellets that are not easily destroyed by wind or rain en route to use. The hope now is to make the process economical enough so that power plants may burn the coal dust.
The coal purchased from Iowa's commercial mines and prepared at the university's experimental coal cleaning plant is burned at the power plant on campus and meets much of the university's energy needs.
For two years in the mid-70s the Iowa Coal Project kept open an experimental mine of its own. All layers removed other than the coal itself were carefully replaced, including the drained and fertilized topsoil. Soybean and corn yields on the land have been improving ever since, says Mr. Birlingmair, and the site is considered a model for surface miners and land owners.