Dust Control Handbook for Industrial Minerals Mining and Processing

There are three primary root causes for fugitive dust emissions associated with conveyor belts:spillage, carryback, and airborne dust (Figure 5.2). Control of all three primary dust sources isnecessary to eliminate fugitive dust emissions.Controlling Material SpillageFigure 5.2. Types of fugitive dust emissions from conveyor belts.Material spillage from a conveyor belt is caused by a lack of material control, either at a transferpoint or along the transfer route. Spillage along the transfer route is generally associated withcarryback, a condition discussed later in this chapter.The most prevalent location for material spillage is at transfer points. Material may be depositedvirtually anywhere along a conveyor, but always leaves the conveyor at the head pulley. In orderto effectively control material at transfer points, the following four steps are used.1. Feeding material onto the belt in the direction of travel and at the same speed as thereceiving conveyor.2. Keeping the fed material centered on the conveyor belt.3. Minimizing the transfer distance which, in turn, minimizes material impact on the beltand air entrainment within the material.4. Using skirtboard ("skirting") to manage the loaded material as it travels on the belt.Each of these steps will be discussed in detail below.Step 1. Feeding material onto the belt in the direction of travel and at the same speed as thereceiving conveyor. Figure 5.3 shows a conveyor head pulley (top conveyor) feeding materialonto a conveyor tail pulley (bottom conveyor). This figure depicts the simplest of transferpoints, where the feeding and receiving conveyors are in-line with each other. The material isbeing fed in the same direction and the speed of the bottom conveyor should match, as closely asis possible, the top conveyor's speed.134 Conveying and Transport