An Updated Reactive Fraction Model to Simulate the Zn Slag Fuming Process

Zn slag fuming technology is widely used for the disposal of Pb and Zn blast furnace slags to recover valuable metals. In this work, an updated reactive fraction (URF) model is developed and coupled with a ChemApp-based thermodynamic model to describe the Zn fuming process. To determine the URF model parameters, laboratory experiments are conducted, and the results are compared with the model predictions. This model is applied to investigate the kinetics of Zn slag fuming. The findings show that the variation of the reactive slag (gas) fraction in the reaction zone can be described by a mathematical model of damping vibration. Zn fuming is dominated by the reactive gas fraction, and the process consists of three stages. In the initial fuming stage, the fuming is unstable, where the Zn content of the slag decreases quickly at the beginning; afterward, the decreasing speed slows down. The main fuming stage shows a rapid fuming rate and contributes significantly to the Zn fuming from the slag. In the final fuming stage, the fuming curve nearly levels off. The Zn fuming mainly occurs in the initial and main fuming stages.