Dust Control Handbook for Industrial Minerals Mining and Processing

Normally, screw conveyors are totally enclosed except at the ends, where dust emissions can becontrolled by proper transfer chute design. The screw conveyor cover is usually fastened by nutsand bolts. However, to maintain a proper dust seal, a self-adhesive neoprene rubber gasketshould be installed.Screw conveyors are essentially dust- and spillage-free as long as the casings, packing glands,and transfer chutes are properly designed and maintained. The only location where spillagetypically may occur is where the screw shaft exits the screw conveyor housing. Pedestalmountedpillow block support bearings (Figure 5.18) should be used and mounted outside thecasing. Packing gland seals can be installed where the shaft exits the casing and before thebearing. This will prevent spillage and protect the bearings.Figure 5.18. Packing gland and pillow block support bearing.BUCKET ELEVATORSA typical bucket elevator (Figure 5.19) consists of a series of buckets mounted on a chain or beltthat operates overhead and tail pulleys. The buckets are loaded by scooping up material from theboot (bottom) or by feeding material into the buckets. Material is discharged as the bucketpasses over the head pulley.148 Conveying and Transport