MODELING THE PYROPROCESS KINETICS OF SHALE EXPANSION IN A ROTARY KILN

The lightweight aggregate industry employs the rotary kiln as the prim ary device for high temperature processing of shale, slate or clay. Th e product, an expanded shale aggregate, is used in many masonry applic ations including high-rise buildings, bridge decks, etc. Like all rota ry kiln processes, achieving product uniformity is a challenging task despite the typically long residence times. A mathematical model has b een formulated to describe the expansion of shale, slate or clay in th e high temperature region of the rotary kin. The model predicts transi ent temperature distribution within a shale particle and simultaneous density changes due to the expansion kinetics (bloating) of the materi al. A major application of the model is found in the process control d epending upon two predicted non-dimensional parameters, the Peclet and the Damkohler numbers.