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United Companies, an Oldcastle division that operates six hot-mix asphalt plants in Colorado, is forging new territory in plant efficiency by turning to an old, reliable fuel source — coal.

Jim Bryan, construction/plant manager for United, says the rising cost of fuel, including waste oil, was a factor in his decision to find a more economical means of producing mix at the company's Grand Junction facility in Western Colorado, but the frequent lack of adequate supply of waste oil played a more dominate role in moving forward to finding a better way.

United's Grand Junction operation consists of a 300-tph Astec Double Barrel™ relocatable plant that was installed in 2000. It was fired by a combination waste oil/natural gas burner and produces between 150,000 and 200,000 tons of HMA annually.

"We purchased another Astec plant last year for one of our other locations and they (Astec) were talking about a new coal burner design they were working on," says Bryan, who's been with United for 20 years. "I was intrigued by the concept of burning coal and so I inquired about the possibility of converting this facility (Grand Junction) to a coal-fired burner. We (United and Astec) did some research (the availability of coal near the facility, as well as cost analysis of burning coal versus other fuel sources) and then we put together a proposal to purchase a coal-fired burner.

"One of the biggest issues that made the coal-fired technology an attractive option was the fact that our supply of waste oil was not reliable," Bryan adds. "It seemed like every year in late summer we were unable to get the used oil we needed to maintain production, and that meant burning other fuel sources at a much higher cost."