Reducing the need to landfill huge amounts of reusable debris from road repair includes the processing of these materials during which a great amount of dust is produced. A California company solved its dust problems with an special water mist generator. At first, the company tried to reduce the amount of dust with a sprinkler system. But that just saturated the material and creating a lot of mud, whereas the dust still remained an issue.
A leading west coast recycler of asphalt and concrete material from large demolition and road projects has successfully employed an atomized mist dust suppression system to control air quality in and around its Chula Vista plant. Reclaimed Aggregates Inc. (RAI) occupies 5 acres in Southern California, operating one of the largest pavement salvage and reclaimed asphalt pavement (RAP) production facilities in the region. By upgrading the dust suppression from a sprinkler system to a DustBoss DB-45, operators report a substantial air quality improvement in the material receiving area.
RAI was formed as a subsidiary of Pavement Recycling Systems (PRS) in 2005, with its first two locations in Colton and Lancaster. In 2009, the company’s Chula Vista facility was added and acts as its largest processing location, receiving and processing concrete and asphalt recovered from multiple road and construction demolition projects. Since opening, the business has expanded its scope to service hundreds of contractors and companies, as well as local and state government projects.
Dozens of dump trucks per day deliver recovered pavement from projects all over the San Diego area to the Chula Vista site. Material is offloaded onto a 200’x200’ dry earth receiving area and immediately moved by front loader to the crusher or into storage piles.
“The offloading process creates a tremendous amount of dust, and that was causing issues for our neighbors who run large vehicle salvage lots,” said facilities manager Robert Erautt. “At first, we tried to reduce the amount of dust with a sprinkler system. But that just saturated the material, creating a lot of mud, whereas the dust still remained an issue.”
Company officials reviewed the options and during their investigation discovered the DustBoss series of suppression equipment from Dust Control Technology (Peoria, IL). They chose the DB-45 based on its range, which is well suited to the size of the area requiring dust management. The unit is able to throw its atomized plume 150 feet (45 m) to deliver effective dust control over a 12,000 square foot (1,115 m²) area. When equipped with optional 359° oscillation, the design can cover as much as 74,000 square feet (16,875 m²) from a single location.
The mist is created by a stainless steel manifold with 18 brass atomizing nozzles delivering 80+ PSI (5.52 BAR) of pressure, propelling millions of droplets with an 18,000 CFM (8.5 m³/sec), 15 HP industrial fan. The DB-45 delivers a dense curtain of water droplets atomized to a 50-200 micron size range, which creates the greatest attraction to most dust particles.
“The size range is critical to avoid the ‘slipstream’ effect that large droplets from sprinklers have on airborne dust particles,” explained DCT President Laura Stiverson. “In most applications, fugitive particles are generally around 50-100 microns in size, but water droplets from a sprinkler are much larger, often 2000 to 6000 microns,” she said. “The velocity of the large sprinkler droplet affects the airflow, and when an airborne particle approaches it, the flow often deflects the particle without a collision between dust and droplet.”
In contrast, the atomized mist system creates droplets that are much closer in size to the dust particles, which encourages the necessary contact to bring dust particles to the ground. The sheer number of these miniscule droplets also increases the surface area available to contact airborne particles, without over-saturating the debris. While large sprinklers can apply 500 gallons per minute or more, the DB-45 puts out just 11.3 GPM at 100 PSI inlet pressure, helping RAI prevent mud and minimize runoff.
“The Dustboss made an immediate impact,” Erautt continued. “On hot dry days — which we get a lot of around here — a little breeze can carry dust a long way. We just turn on the atomizer and you can see the mist pull the dust out of the air.”
After turning on the atomizer, you can see the mist pull out the dust.