Dust Control Handbook for Industrial Minerals Mining and Processing

DUST SUPPRESSION HOPPERAnother modification that can be made in an effort to reduce dust emissions during bulk loadingis the utilization of the Dust Suppression Hopper (DSH) [DSH Systems 2010]. The DSH islocated at the product discharge point and is designed to help the loaded product flow more as asolid column of material with less exposed surface area to minimize entrainment into the ambientair [Wypych 2009]. The hopper is equipped with a central plug at the bottom to preventdischarge of product until a predefined quantity has accumulated in the hopper. Either springs ora programmable logic controller are used to set and control the amount of clearance between theplug and the hopper. Material is loaded into the top of the hopper and contained until sufficientweight forces clearance between the hopper and plug. Material then flows from the hopper inmore of a solid column, as shown in Figure 7.6, rather than in a free-falling unconsolidatedstream. This overall process results in less dust liberation [Biere et al. 2010].Figure 7.6. Dust Suppression Hopper creating a solid stream ofmaterial during loading to reduce dust liberation.ENCLOSURESDuring bulk loading, the preferred method of dust control is to prevent dust from becomingairborne. However, if dust is released into the ambient air, efforts must be made to keep the dustfrom reaching the breathing zone of surrounding workers. This can be accomplished byenclosing the dust-generating process or enclosing the worker. Both of these methods will bediscussed and illustrated below.Enclosed LoadoutThe goal of enclosing the loadout area is to contain and capture the airborne dust so that it cannotreach the breathing zone of nearby workers or contaminate the surrounding environment.Typically, this type of control will be used for the loading of trucks or railcars. Essentially, aphysical barrier is constructed that confines the dust that is generated as loading occurs. Thebarrier also minimizes the impact of environmental factors such as high wind velocities. Thesebarriers can be permanent walls with flexible plastic stripping, belting, or curtain used to provide194 Bulk Loading