MRO Magazine

Blown Away: Ontario steel mill boosts safety by preventing dust migration


Industry

December 3, 2012
By PEM Magazine

One of the largest mini-mill steel producers and recyclers in North America is putting a “wet blanket” on slag dust from ladle and tundish dumping, improving safety and cleanliness while preventing dust migration. The Gerdau Ameristeel facility in Cambridge, Ont., uses a specially-designed atomized mist system developed specifically for dust suppression, reducing potential hazards and improving visibility around the dumping pit and in the nearby service area.

This facility has the capacity to produce 300,000 standard tons annually of low to medium carbon steel bars, primarily from feedstocks of recycled materials.

“At the end of a casting sequence, several tons of slag can be left over that must be purged,” senior engineer John Andric explained. “When ladles and tundishes are dumped, the falling slag has the potential to create large quantities of dust.” In short, he said, “We needed something that could control the dust quickly as it was generated, at ground level.”

After seeing a Dust Control Technology unit in action in another steelmaking facility, they opted to specify a DB-30 for the slag dump area, the smallest member of the DustBoss product family. Mounted on a movable carriage, the unit has a 7.5-horsepower motor that generates 9,200 CFM of airflow. The ducted fan design has an adjustable throw angle from 0º to 50° elevation and the standard unit oscillates up to 70º. When equipped with the new 359-degree oscillation option, the DB-30 can cover more than 30,000 square feet using just a standard 5/8-inch garden hose.

Advertisment

According to Dust Control Technology CEO Edwin Peterson, there are typically three different opportunities for fugitive slag particle emissions to emerge during steel processing. “The first is from the initial fall of material, and is usually of short duration,” he said. “The second occurs during subsequent tempering and cooling operations, when vapor from the cooling water rises and carries particulates into the air. Dust can also be released any time a particle’s terminal settling velocity (from gravity) is lower than the thermal updraft velocity (from heat), which causes it to rise and potentially migrate.”

Unfortunately, slag dust is made up of a number of different-sized particles, some of which are extremely small and lightweight, therefore mobile. DustBoss equipment has been extensively tested at a number of slag processing sites, with various modifications and configurations evaluated in a range of combinations to gauge their effectiveness. One of the keys to the equipment’s success has been the ability to automate operation, allowing slag processors to control on/off cycles, direction, oscillation arc and other features from a remote location or via hand-held wireless control. Fully integrated systems can be operated entirely by remote control whenever a slag dump is underway.

At Gerdau Cambridge, the DB-30 is mounted in an elevated location above the dump area and direct wired to 575 volt, 3-phase service. The company uses the city water supply, delivered through a heat traced and insulated line, so pressure remains at a fairly constant 40-60 PSI (2.76-4.14 BAR).

Andric says he’s pleased with the results from the DustBoss: “It does just what it was designed to do, delivering the mist over a wide coverage area.”


This is an edited article provided by Dust Control Technology. For more information, visit www.dustboss.com.