Dust Control Handbook for Industrial Minerals Mining and Processing

Figure 6.8. Exhaust hood to capture and exhaust respirable dust away from each fill nozzle.Exhaust Hoppers (Below Entire Fill Station)Similar to the above technique, which places an exhaust hood around each individual bagloading unit, a hopper can also be placed below the entire fill station to capture and recycle allthe dust and product lost from the entire bag loading area or station. This is especially beneficialwith three- and four-fill-nozzle bag loading systems. In these cases, incorporating the LEV intoa single-hopper design is easier and more financially advantageous than trying to connectductwork to individual hoods around each fill nozzle.Figure 6.9 shows a typical design for a single-hopper LEV type system. One critical designcomponent is to locate the exhaust system takeoff points high in the hopper unit and in closeproximity to the actual bag loading area. The heavier dust and product that is not captured by theexhaust system simply falls into the base of the hopper and is recycled back into the product lineusing a screw conveyor.Bagging 167