Dust Control Handbook for Industrial Minerals Mining and Processing

Figure 1.14. Typical design of gravity separator (drop-out box).The benefits of using gravity separators are that they require little maintenance and they reducethe load on the primary dust collector. However, they also take up significant plant space andhave a low collection efficiency.Centrifugal Collectors or CyclonesCyclones are a dust collection device that separates particulate from the air by centrifugal force.The cyclone works by forcing the incoming airstream to spin in a vortex. As the airstream isforced to change direction, the inertia of the particulates causes them to continue in the originaldirection and to be separated from the airstream (Figure 1.15). Although, the cyclone is simplein appearance and operation, the interactions inside a cyclone are complex. A simple way toexplain the action taking place inside a cyclone is that there are two vortices that are createdduring operation. The main vortex spirals downward and carries the coarser particles. An innervortex, created near the bottom of the cyclone, spirals upward and carries finer dust particles.Fundamentals of Dust Collection Systems 29