Dust Control Handbook for Industrial Minerals Mining and Processing

Figure 5.19. Depiction of a bucket elevator.A steel casing usually encloses the entire assembly and effectively contains dust unless there areholes or openings in the casings. Dust emissions typically occur at the boot of the elevator wherematerial is being fed into the elevator or at the head of the elevator where material is beingdischarged.Emissions at the boot of the elevator can be controlled by proper design of a transfer chute(similar to belt conveyors) between the feeding equipment and the elevator. Dust can be reducedsignificantly by keeping the height of material fall to a minimum and by gently loading materialinto the boot of the elevator.Controlling dust emission at the discharge end of the bucket elevator can be accomplished byproper venting to a dust collector (see Chapter 1—Fundamentals of Dust Collection Systems), aswell as through the use of proper enclosures and chutes between the elevator discharge and thereceiving equipment. It is recommended that at least 100 cfm of dust collection air be providedfor every square foot of casing cross-sectional area [ACGIH 2010]. Dust collection pickupshould be provided from the top of the casing, just above the head pulley (Figure 5.20).Additional ventilation may be needed for belts traveling over 200 fpm. If the elevator is over 30feet tall a second pickup should be installed on the side of the casing just above the tail pulley.Dust collection ventilation should also be provided where the material is being discharged intothe elevator.Conveying and Transport 149