Kinetics of Carbothermal Reduction of Zinc Ferrite

• Main Authors: JYH-JEN LEE, 李志仁
• Other Authors: CHUN-I LIN
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/41745166098073330366

碩士 === 國立臺灣科技大學 === 化學工程系 === 88 === Kinetics of carbothermal reduction of zinc ferrite was studied in this study. A box furnace was used to synthesize zinc ferrite. X-ray diffractometer, wetting-chemical analysis method, surface area meter and scanning electron microscope were employed to monitor the changes of composition and physical properties during reaction. On the other hand, thermogravimetic analyzer was used to study the effects of processing parameters on the conversion rate of zinc ferrite. It was found that zinc ferrite of 96.84% pure could be synthesized under following conditions : molar ratio of ZnO/Fe2O3 of 1 ; air flown over sample through suction of hood ; temperature of 1,123 K and time of 18,000 s. Zinc ferrite was found to decompose to ZnO and Fe2O3 initially. ZnO was then rapidly reduced to zinc vapor and carbon monoxide which were escaped from solid sample. Fe2O3 was also reduced FeO. However, the rate was slower. It was transformed to Fe through FeO. Pore surface area of solid sample increased with reaction time while pore volume and pore diameter were increased and then decreased with time. They are due to the escaping of zinc vapor and the expansion of FeO. A model was proposed to explain the reaction. As to the effects of processing parameters on the rate of carbothermal reduction of zinc ferrite, following results were found : conversion rate of zinc ferrite could be increased by increasing the flow rate of agron stream or reaction temperature. The rate was also found to be increased by decreasing the height of solid sample, molar ratio of ZnFe2O4/C, the grain size of carbon agglomerate or the initial bulk density of solid sample.