Experimental and theoretical study on the fluidization behaviors of iron powder at high temperature

Fluidization behavior of iron powder in N-2 was investigated in detail under the fluidization gas velocity of 2-10 u(mfo) at 600-800 degrees C. Four types of fluidization behaviors, i.e., stable fluidization, agglomerating fluidization, gradual defluidization and fast defluidization, were expressly described and distinguished, instead of only two types (i.e., fluidization and defluidization) reported in the literature. Further investigation revealed that the occurrence of different types of fluidization behaviors was caused by the differences in the formation and growth of agglomerates under different fluidization conditions. Particularly, gradual or fast defluidization was caused by the continuous formation and growth of agglomerates in the whole process. However, if formation and growth of agglomerates could Finally reach equilibrium, agglomerating fluidization would occur without defluidization. Moreover, a theoretical model was proposed based on the force balance analyses between the collision force and the cohesive force. Through the analyses of the formation and growth of agglomerates, the occurrence of four fluidization behaviors was well explained, especially for the agglomerating fluidization and gradual defluidization. (C) 2014 Elsevier Ltd. All rights reserved.