After successful deployment of a DustBoss® Ring (DB-R) on its barge-loading conveyor, Hendricks River Logistics (HRL) has added another unit to its larger conveyor, which feeds the stockpile area, significantly reducing the amount of fugitive dust in the entire work site. Effective dust management has been cited by company officials as an important component of the facility’s environmental stewardship and regulatory compliance.
Located on the Mississippi River, just north of Keokuk, Iowa/USA, HRL exclusively serves two utilities along the Mississippi River. Trains as long as 123 cars, loaded with sub-bituminous coal, take the 5.5-day round trip to HRL’s site. The train enters a 3-mile spur track off of the main BNSF (Burlington Northern Santa Fe) line. Each car is unloaded using a rotary dumper, a large cylindrical framework with its own track, which braces onto the car with hydraulic clamps, then turns the car and track nearly 160°, emptying the contents into a large hopper. The rotary dumping sequence takes about two to three minutes per car, allowing the facility to process approximately 2700 t/h from its receiving area. The coal is loaded onto conveyor belts leading to the stockpile that is appx. 300 m uphill from the rotary dumper. The main discharge belt is 1,54 m wide and feeds into the 56000 m2 stockpile that is managed by bulldozer.
For reducing dust, a large 72-inch DB-R made of stainless steel and circular manifold with 38 misting nozzles is mounted on the conveyor 1 m below the discharge point, pumping 90 l/h of atomized water. The DB-R creates a circular curtain of 50-200 micron sized droplets, which travel with the dust, absorb the particles and pull them to the ground with little or no pooling or runoff. Pressure is adjustable to match the fluctuations in volume of fugitive dust dispensed from the belt. The size of the mist droplets does not change regardless of the pressure.
“Visiting the site, we noticed the main discharge point was high enough for air currents to carry dust a long distance,” said Carl Harr, who handles Technical Sales for Dust Control Technology, manufacturer of the DustBoss line of products. “It does twice the volume of the barge loader, but since it’s located on a hill, it creates greater potential for migration, so adding a new DB-R in that location was an excellent choice.”