| A mathematical model to simulate the reaction kinetics of dust--carbon composite agglomerates in an RHF was developed. Major chemical, thermal and physical phenomena taking place during RHF treatment were formulated and the corresponding equations were solved to yield the trend of solid composition, temperature and gas composition of the agglomerates. The model calculation results indicate that the pellet reduction is accelerated by the reducing gas from high-volatile reductants if the gas is released after the pellet temperature is sufficiently high for reduction. The reduction of zinc oxide can also be represented using the model by implementing its small particle size caused by the inherent vaporization/re-oxidization process that zinc comes through in a melter. It was demonstrated that the proposed model can be used as an engineering tool to determine the optimum operating conditions for the RHF process to promote recycling a wide range of waste materials. |
