Modeling of Cohesive Metal-induced Agglomeration in High Temperature Gas Fluidization: The Role of Particle Size

The defluidization behavior of cohesive metal particles with different sizes in high-temperature gas fluidization was studied experimentally and theoretically. Taking iron particles as an example, first, we theoretically assessed the variation in sintering neck size with the characteristic parameters (particle size d(p), temperature T, gas velocity u(g), and sintering time tau) in high temperature gas fluidization and found that larger particles can form a greater sintering neck and induce a shorter sintering time (collision contact time). In particular, the calculated results with different empirical correlations are quite different. Then, according to the microstructure observations, we assume that a stable sintering neck is formed between the metal particles when defluidization occurs. On the basis of this, a quantitative relationship between particle size and operating parameters (temperature and gas velocity) is established, where appropriate empirical correlations are selected by fitting the experimental results. Furthermore, it is demonstrated that the new model can successfully predict the defluidization behavior of other cohesive metal particles (Co, Ni, and Cu) with different sizes in high temperature gas fluidization.