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S andvik Mining has opted to solve the problem by integrating compressors and jet pulse dust collectors with its surface top hammer drill rigs. According to the US National Institute for Occupational Safety and Health (NIOSH), jet pulse collec- tors, also called reverse jet collectors, deliver high collection efficiency. Depending on the type of rig, the dust collector consists of between nine and 12 sock-shaped filter bags. Dust-laden air flows into the bags, leaving the dust to collect or 'cake' on the outside. Timed blasts of compressed air into the bag shake the cake from the out- side into the collector where it is deposited safely. Frequent jet pulse cleaning of the fil- ter bag keeps the system operating at optimum pressure and airflow. Blow- ing frequency in the Sandvik system is controlled by a timer switch and is adjustable. An important component in the dust collection system is the valve con- trolling the pulse. Sandvik relies on IMI Buschjost valves supplied by IMI Preci- sion Engineering (formerly Norgren) to keep the dust collector operating at peak efficiency. These valves are fast acting, opening in milliseconds to allow air pressure to reach the set point quickly to deliver an intense burst. A rapid, intense burst cleans the cake off the filter bag most effectively. This fast action also reduces demand for compressed air and decreases energy consumption. Additionally, the valves are explosion-proof and are available in high corrosion-resistant models. A significant advantage of the IMI Buschjost valves is their temperature range, thanks to high-grade construc- tion and a frost-proof solenoid. Oper- ated by a one-piece diaphragm rather than springs used in typical valves, the valves perform consistently across a temperature range from -40ºC to 140ºC (temperature class T4/T5). Using the same valve across the complete range of blasthole drill rigs also simplifies ordering specifications. And a single spare part can be reliably supplied to customers wherever they are. The valve's Twist-On design allows replacement without tools. Sandvik opts for jet pulse dust collection system Surface top hammer drill rigs can only operate reliably if the dust they generate is removed from the path of the drill. Otherwise the drill string can become jammed, stopping the operation. However, the dust cannot be simply exhausted into the air, as respirable particles present a significant health and safety hazard to equipment operators and others working nearby "A rapid, intense burst cleans the cake off the filter bag most effectively. This fast action also reduces demand for compressed air and decreases energy consumption" Article from Miningmagazine.com – March 12, 2015 A jet pulse dust collector mounted on a Sandvik surface top hammer drill rig