(2lw) Mathematical Model of the Dezincification Behavior for the Commercial-Scale Rotary Hearth Furnace

Zn contained in byproduct dust of steel production has environmental impacts and presents a challenge in resource management. This work considers dezincification behavior in a commercial-scale rotary hearth furnace to recycle the byproduct dust of steel production. We develop a mathematical model of iron-ore/carbon-composite pellets and suggest a one-dimensional dynamic model that illustrates the non-uniform distribution properties such as temperature and solid weight fraction. By utilizing commercial-scale operational data from the actual process, the Arrhenius kinetics of the ZnO reduction reaction (ZnO + CO → Zn + CO₂) was fitted; the estimated activation energy E_a was 163.6 kJ∙mol^‑1, and the estimated pre-exponential factor was 868.6 m∙s^-1. The high sensitivity of the reaction to temperature was consistent with the high E_a. The simulation results agreed well with the operational data within a relative error of 10%. The validity of extrapolating the simulation condition was verified by testing under conditions of real operation. Six factors that affect the dezincification ratio were identified; in descending order of significance, these were operational time, particle size, temperature, C/O ratio, porosity, and emissivity. A parametric study identified trade-offs between energy, productivity, and product quality. These should be further studied to permit reduce the ecological costs of integrated steel plants. We expect that this study will broaden the understanding of the dezincification behavior in the system and diminish the gap between the research and the industry application.