铁酸锌碳热还原动力学及反应机理

对铁酸锌非等温碳热还原反应动力学及其还原反应机理进行了研究.通过不同温度条件下还原后的铁酸锌团块物相分析(XRD)对其碳热还原的物相转变过程进行了解析，950℃时出现FeO0.85·x ZnO无定型物质，此时Fe³⁺被还原成Fe²⁺.探讨了铁酸锌碳热还原过程转化率与转化速率的关系，该还原过程可以划分为三个阶段，第二阶段的转化率变化最大(0.085～0.813).最后，通过等转化率法和主曲线拟合法对不同升温速率条件下铁酸锌碳热还原第二阶段的动力学进行了分析，可以得出第二阶段的平均活化能为362.16 kJ·mol^–1，且该阶段活化能为331.01～490.04 kJ·mol^–1，变化较大，说明这一阶段发生的反应较为复杂，且各反应之间的活化能差异明显，二级化学反应是这一阶段的主要控速环节，并确定了第二阶段的主要控速方程.

Kinetics and reduction mechanism of non-isothermal analysis carbothermal reduction of zinc ferrite

The amount of zinc-containing EAF dust has increased due to the increased proportion of galvanized steel scrap used in the electric arc furnace (EAF) steelmaking process. If the zinc in the EAF dust is not recycled, it will not only lead to a waste of valuable metal resources but also results in environmental pollution. Zinc is mainly present in the EAF dust in the form of zinc ferrite (ZnFe₂O₄). Zinc ferrite is a kind of spinel mineral that exhibits a crystal lattice of greater stability, which increases the difficulty of recycling valuable elements such as zinc and iron from zinc-containing EAF dust. To further clarify the carbothermic reduction process of zinc ferrite, this paper studies the kinetics of the non-isothermal carbothermal reduction of zinc ferrite and its reduction reaction mechanism. The phase transition process of the zinc ferrite carbothermal reduction reaction was analyzed via the XRD results of the reduced zinc ferrite. FeO_0.85·xZnO was found at 950 °C when Fe3+ was reduced to Fe2+. The relationship between the conversion and conversion rate of the zinc ferrite carbothermal reduction process is discussed. The reduction process can be divided into three stages, and the conversion of the second stage changes greatly (0.085–0.813). Finally, the kinetics of the second stage of the carbothermic reduction of the zinc ferrite at different heating rates was evaluated through the isoconversional method and the master curve fitting method. The activation energy of the second stage is between 331.01–490.04 kJ·mol?1, and the average activation energy is 362.16 kJ·mol?1. The large change in the activation energy in the second stage indicates that the reactions in this stage are more complicated, and there are obvious differences in the activation energy between the reactions. The secondary chemical reaction is the main rate-controlling link in the second stage, and the kinetics equation of the second stage is determined.