Dust Control Handbook for Industrial Minerals Mining and Processing

Figure 4.16. Illustration of a dry (exhaust) dust control system on a vibrating screen.Exhaust air take-off location must be carefully considered so that desirable fines (product) arenot collected. Locating the take-off closer to the discharge (away from the feed end) of thescreen will help avoid the loss of desirable fines. Also, collection of undersized material can bereduced by using take-off openings large in area to reduce the air entry velocity.Work Practices to Minimize Dust Exposure from ScreensThe following practices should be observed where compatible with installed equipment andexisting operating procedures.Clean equipment and area before and during work, when needed, preferably by washingor vacuuming.Stop material flow before cleaning screens, if operationally feasible. The absence offlowing material minimizes the potential for dust emissions.When cleaning, only open the top or the bottom part of screen decks at a time. Do notopen both at the same time. The larger the size of the opening, the less effective theventilation system can be.Only open one screen at a time during cleaning. Do not open multiple screenssimultaneously. Again, numerous openings decrease the capture effectiveness of aventilation system.When cleaning screens, only use long-handled brushes that will provide more distancebetween the worker and the dust source.Consider variable speed vibrators that significantly reduce the frequency of manualcleaning of screens. The less time cleaning screens, the less the potential for dustexposure.Crushing, Milling, and Screening 127