Design of a dust tower for suppression of airborne particulates for iron making

Proper characterization of a dust suppressant represents a significant challenge. There has been confusion on what makes an effective dust suppressant. Many have argued that a dust suppressant must wet the material effectively and rapidly to control airborne dust. As a result, dust suppression studies have been heavily dependent upon laboratory wetting experiments such as contact angles, fine particle engulfment rates, and particle bed experiments to characterize dust suppressants. It has been believed that an effective dust suppressant should produce a low contact angle, and engulf particles rapidly thereby wetting the surface effectively and reducing airborne dust levels. However, these methods only characterize how the suppressant wets a given material, which does not directly correlate to the ability to suppress dust. Furthermore, a clear correlation between wetting enhancement and dust suppression has not been demonstrated. In order to address this gap, a novel dust tower was constructed which provided direct material dustiness measurements and allowed for a more realistic evaluation of dust suppressant effectiveness. This unit was able to clearly distinguish differences in dustiness that resulted from treatment of iron ore pellets with several different dust suppressant chemicals.