Mining Publication: Development of a Lower-Pressure Water-Powered Spot Scrubber for Mining Applications

• Scrubbers
• Water mist systems
• Water sprays
• Wetting of deposited dust

Water sprays and water-powered scrubbers have both been used in the mining and milling industry to suppress airborne dust. Unconfined water sprays operating at lower water pressures (less than or equal to 100 psig) can be very effective at wetting the mine product at the dust source and significantly reducing the amount of respirable dust that becomes airborne. However, unconfined water sprays can be somewhat ineffective in actually removing airborne dust from the air. On the other hand, water-powered scrubbers operating at higher water pressures (greater than or equal to 250 psig) in physical enclosures or ducts have previously been shown to be very effective in removing airborne dust from the air. These higher operating water pressures are very uncommon to many mines and mills, so their use is limited. The National Institute for Occupational Safety and Health recently investigated the performance of a lower-pressure, water-powered in-line series spray scrubber for removing localized airborne dust emitted at the source. Results showed noticeable improvements in airborne dust capture efficiency through the operation of multiple in-line series hollow cone spray nozzles within a round duct of pipe at the same water pressure as a single spray. Operating hollow cone spray(s) at higher water pressures noticeably improved airflow through the scrubber and yielded some additional scrubber efficiency improvements. Thus, in-line spray scrubber efficiency tradeoffs were observed to be made by altering spray power components of water pressure and/or quantity (number of sprays). Results show that, on average, up to 484 and 679 cubic feet per minute of airflow at 0.69 and 0.81 dust capture efficiencies can be achieved with three 81- and 33-deg hollow cone in-line series sprays, respectively, operating at 240 psig.