Cut and Dry
In addition, the dry classification has helped reduce manpower and equipment needed to dredge wet pond fines, because it has reduced the amount of washing needed for the site’s screenings.
But the bigger benefit for Tilcon has been the fuel savings that the air classification has indirectly provided downstream at the company’s on-site asphalt plants. According to Rebecca Guardino, quality manager at Mount Hope, the manufactured sand that feeds the asphalt plants now has much lower moisture content than it previously did.
“We’ve seen a big difference in fuel savings at the asphalt plant now that we have drier sand going into the mix,” she says. “Previously, feeding the asphalt plant with washed sand, we were looking at a moisture content of 5 percent.” By using the air classification system, however, the moisture content dropped to between 1 to 1/2 percent.
With drier material going into the asphalt drum, Tilcon uses less fuel to process the asphalt material, while also increasing throughput. “Depending on the type of fuel we’re using in the plants, we have seen between 10 and 20 percent savings in fuel costs at the asphalt plant,” says Jiries (Jerry) Saba, electrician supervisor at Mount Hope, explaining that the Mount Hope asphalt plant uses natural gas, and he’s seen a 10-percent decrease in fuel costs at that site. “Other locations use spec’d oil, and they’ve seen a 15- to 20-percent decrease in fuel costs,” he adds.
While 10 to 20 percent fuel savings might not seem large at first glance, an example of actual dollars saved better drives the point home. Saba offers a savings scenario: “Say the fuel you’re using is currently $4 per gallon, and it takes 1-1/2 gallons to process a ton of material. You look at how many gallons of fuel you’re using per hour.” Using these parameters, a 350-ton-per-hour asphalt plant would require 525 gallons of fuel each hour, at a cost of $2,100. An eight-hour shift alone would use $16,800 in fuel to process the asphalt. And even a modest 10 percent savings of $1,680 per shift is significant. With fuel costs continuing to soar, the savings are even more important.
In addition, because it weighs less, dry sand is less costly to haul to other asphalt plant locations — providing additional fuel savings.
Between its impact on rising energy costs and its ability to improve efficiencies at the asphalt plant, Guardino notes that the classifier has become more and more of a valued piece of equipment at the site.
Hard wearing despite hard rock
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