Tinley Park firm turns coal byproduct into granules for roofing, blasting industries

Granted, the phrase "coal slag" isn't likely mentioned many times in your office.

Michael Johnston knows that too well, as he finds himself explaining the term when he discusses his business with others.

"Most people say, 'You do what?'" the president and CEO of Tinley Park-based U.S. Minerals quipped.

In simple terms, coal slag is the hard, black, crystallized by-product created in coal burning furnaces, such as those in power plants.

Slag's unique properties are created after the burned material at the bottom of the furnace is cooled by water, and it's those properties that make it a core of U.S. Minerals' product line.

The company, which also operates seven plants in the central region of the U.S., processes and crushes the slag and turns it into materials that make up the firm's two main product lines: granules used in roofing shingles and variable-sized grains that are used the in blast abrasive cleaning industry.

In the roofing business, Johnston says six of the eight major manufacturers of roofing shingles use U.S. Minerals' products, including GAF, CertainTeed, Atlas and Tamko.

"Because coal slag is typically a black material, they use it for black shingles and shadow lines shingles that create more of an architectural effect," he said.

"But it's primarily used as headlap - the section of the shingle underneath the overlap of the shingle above it - because it's less expensive than the colored granules that make up the wide variety of colors you can put on your roof."

While it can vary among markets, Johnston estimates up to 30 percent of the homes in the Chicago area use roofing shingles that contain his company's materials.

On the other side of U.S. Minerals' product line is its Black Diamond abrasives used in blast cleaning of large iron or steel structures, ranging from bridges and water towers to railcars and farm equipment. Abrasives are a custom-fit, Johnston said, as the company can create the abrasive material to be as fine or coarse to handle a customer's projects, and quantities can be as specific as the customer needs.

"We ship anything from 50 pound bags to railcars of 100 tons to our customers," Johnston said, adding the railcar-load customers are "typically folks who are doing major structures, like a painting contractor who does water towers as their primary market niche."

While the vast majority of customers are businesses, Black Diamond abrasives are available for retail customers in 50 pound bags through a few supply store chains.

The prime customers in that niche are typically farmers who use the material to clean and repaint farm equipment, Johnston noted.

While coal slag is a major ingredient in U.S. Minerals product line, the company also provides roofing and abrasive products that use iron silicate, and the Black Diamond line also provides specialty abrasive materials, from glass beads to corn cobs.

U.S. Minerals processes between 400,000 to 500,000 tons of coal slag a year, Johnston said. He adds the repurposed use of slag also keeps the material from becoming waste.

"Would we not do this processing and make it usable by our customers, it might end up in a landfill," Johnston said. "It's a significant diversion of materials going into landfills."

In fact, Johnston notes the company works to be environmentally responsible by finding uses for slag that they obtain but cannot use.

"We're always looking for ways to sell everything we create and use everything we buy in some productive way," he said. For example, unused material may be sold to an asphalt company that would blend the particles into a top coat of a driveway or parking lot to make the surface less slippery.

He said, "We do look aggressively to get as much it sold as we can."

U.S. Minerals

<b>18635 West Creek Drive </b><b>Tinley Park, IL 60477</b><b>(800) 803-2803</b><b>www.us-minerals.com</b>Top Official: Michael Johnston, president and CEO

Employees: 100

Annual revenue: $20-$40 million

Best known product: Roofing granules and Black Diamond abrasives

Other locations: Processing plants in Coffeen and Baldwin, IL; Harvey LA; Galveston TX; La Cygne KS: Roberts, WI and Anaconda, MT.