Dust Control Handbook for Industrial Minerals Mining and Processing

entire pallet loading cycle. The lift table is set to approximately knuckle-high for the worker,which is the most ergonomic loading height (Figure 6.15). A push-pull ventilation system isused on either side of this pallet to capture the dust liberated during the bag stacking (palletizing)process [Cecala and Covelli 1990]. This system is composed of a low-volume, high-velocityblower operating at approximately 120 cfm to direct a stream of air over the top layer of bags onthe pallet. The blower system is composed of two 3-inch air jets (approximately 1,200-fpmvelocity) directed towards an exhaust system on the opposite side of the pallet. As these air jetstravel approximately 10 to 12 inches above the top of the pallet, they entrain the dust generatedduring bag stacking. The exhaust ventilation system pulls approximately 2,500 cfm of air anddust through the exhaust hood. This exhaust air can then be dumped into an LEV system.Figure 6.15. Semi-automated bag palletizing system to ergonomically improve bag stackingprocess with a push-pull ventilation system used to capture the dust generated.In other cases involving palletizing systems, the worker slides the bag of product on an air tableone layer at a time, but the actual stacking of the bags onto the pallet is performed automatically.Since back injuries represent such a major lost-time injury potential for bag stackers, this designsignificantly reduces back stress by eliminating the need to manually lift any bags of product.One problem with an air slide device is that it can cause dust to be blown from the bags ofproduct into the worker's breathing zone. An OASIS system (see this chapter's earlier"Overhead Air Supply Island System" section) can work very effectively in conjunction with anair slide device.In addition to the OASIS system, an exhaust hood was also used next to the air slide area tocapture the dust blown from the bag (Figure 6.16) [Cecala et al. 2000]. With this setup, or any176 Bagging