Dust Control Handbook for Industrial Minerals Mining and Processing

operational conditions this could mean the difference between no material spillage andsignificant material spillage. Therefore, each circumstance must be evaluated individually withthe behavior of the material under conditions of conveyance as a primary consideration.Table 5.2. A comparison of CEMA and Army Corps of Engineersrecommendations for skirting for a belt speed of 600 fpmCEMAArmy Corps of Engineers2 ft of skirting for every 100 fpm 5 ft plus 1 ft of skirting for every 100 fpmof belt speedof belt speed2 ft x (600 fpm/100 fpm) = 12 ft of skirting 5 ft + (600 fpm/100 fpm) = 11 ft of skirtingAn inclined skirting design, in which the skirting belt is angled at approximately 30 degrees fromvertical, is more advantageous over a standard vertical design because of wear issues. Thisskirting design improves the loading of ore onto the conveyor and reduces the amount of dustgenerated.Dust curtains (Figure 5.11) are an effective and inexpensive containment device that should beinstalled at the entrance and exit of the chute enclosure. Some design guidelines include:Exit air velocity from the enclosure or chute should be kept below 500 fpm to minimizethe entrainment of large particles [Yourt 1990].Dual rubber curtains should be hung roughly 18 inches (450 mm) apart from each otherto form a "dead" area where dust can settle [Goldbeck and Marti 2010].Entrance curtains should extend to the conveyor belt to maximize the containment area.Exit curtains should extend to approximately one inch (25 mm) below the top of theproduct pile [Goldbeck and Marti 2010].Figure 5.11. Typical dust curtain used at the entrance and exit of the chute enclosure.140 Conveying and Transport