ABSTRACT
Dust control using drill shroud air-blocking shelves was confirmed effective. However, when the drilling machine moves to different locations, deposits on these shelves can produce a large dust cloud. To minimize this dust exposure hazard, this study modified the drill shroud air-blocking shelves by utilizing the concept of angle of friction to eliminate the deposits and, at the same time, still be able to confine the dust inside the drill shroud. Two types of inner shape were evaluated using CFD models: U-shaped and V-shaped drill shrouds. In addition, a drill shroud with 45° blocking shelves was also built to examine its dust control capacity. Based on the study, the angle of friction used to minimize the dust problems during mast lowering was shown to be effective in reducing the dust problems during drilling. However, care must be taken to use a properly designed shroud as the V-shaped drill shroud can potentially exacerbate the dust leakage.
