Dust Control a Key Element of Auto Shredding Operations

With the increasing emphasis on reducing potential health and environmental effects from auto shredding operations, dust control has become an important part of daily operations.

After nearly 30 years in the business, George Adams has seen facility owners graduate from hand-held hoses and sprinklers to high-tech integrated systems that are designed into modern shredding equipment.

Adams' company, SA Recycling LLC, is a joint venture between Adams Steel and the Sims Group Ltd. The company has a network of 27 locations serving California, Arizona, Nevada and Mexico. The firm's Anaheim, Calif., site uses one of the largest auto shredders in the industry, the 124 SXS from the Shredder Co., Canutillo, TX. The shredder features a double feed roller system weighing more than 70,000 pounds, driven by a 7,000 HP motor.

With programmable logic controllers, touch screen monitors and real time data feedback, the "smart" shredder is designed for rapid, consistent decision-making and low per-unit cost. The mega shredder can process about 230 tons of scrap per hour, or around three cars per minute.

Like many of the new shredder plants on the market, the 124 SXS employs a computer-controlled water injection system for initial dust control, which also helps eliminate excess heat. "All of our operations are designed to use the latest technologies to help us meet the highest standards of environmental health and safety," Adams observed.

"Damp shredding is part of the dust control equation," he continued. "But we found that the outflow dries fairly quickly, especially in hot weather. So we wanted to find a way to keep the particulates down, especially when we're loading shredded waste into trucks."

After reviewing several available options, Adams decided on a high-efficiency suppression system from Dust Control Technology, Peoria, Ill., specifying the company's largest model, the DustBoss DB-60. "We run the DustBoss whenever we're loading or moving material," Adams continued. "There's one at the Anaheim facility and another at our Terminal Island location."

The DB-60 is a fully automatic ducted fan design mounted on a wheeled carriage, so it can be easily located to accommodate wind direction or loading area. Able to generate 30,000 CFM (nearly 850 cubic meters per minute) of forced air with its 25 HP fan motor, the oscillating unit blankets as much as 21,000 square feet with a fine mist of water droplets that are atomized to 50-200 microns in size. The unit has a range of up to 210 feet, with an adjustable elevation from 0-50 and 40 of oscillation, providing SA Recycling operators with outstanding coverage of the loading areas.

"The droplet size is critical to effective suppression," explained Dust Control Technology CEO Edwin Peterson. "Fugitive dust particles tend to be in a fairly narrow size range, so the water should be atomized to droplets near that same size for maximum attraction. The nozzles and fan must be designed to work together for optimum flow, spray angle and delivery pressure to achieve the droplet size, velocity and distribution needed."

The DB-60 also incorporates a 10 HP booster pump for extending water pressure by as much as 150 PSI for enhanced particle control. Fed by a 1-1/2' quick-disconnect hose, the unit requires just 10 PSI of constant pressure to supply 30 specially-designed brass nozzles. At a boosted pressure of 200 psi, the machine typically uses between 15-30 gpm (57-114 lpm). The manufacturer also offers an optional dosing pump that can be used to meter in surfactants for superior particle capture. All of the DustBoss designs can be outfitted for potable or non-potable water sources.

"These units have been a great help in trapping dust which might otherwise make its way into the air," Adams concludes. "In fact, we've ordered two more machines to be delivered this year for other facilities." Rick Felde.

The author is with Dust Control Technology. He can be reached at rick@dustboss.com