Reaction condition optimization and kinetic investigation of roasting zinc oxide ore using (NH4)2SO4

An orthogonal test was used to optimize the reaction conditions of roasting zinc oxide ore using (NH4)(2)SO4. The optimized reaction conditions are defined as an (NH4)(2)SO4/zinc molar ratio of 1.4:1, a roasting temperature of 440A degrees C, and a thermostatic time of 60 min. The molar ratio of (NH4)(2)SO4/zinc is the most predominant factor and the roasting temperature is the second significant factor that governs the zinc extraction. Thermogravimetric-differential thermal analysis was used for (NH4)(2)SO4 and zinc mixed in a molar ratio of 1.4:1 at the heating rates of 5, 10, 15, and 20 K center dot min(-1). Two strong endothermic peaks indicate that the complex chemical reactions occur at approximately 290A degrees C and 400A degrees C. XRD analysis was employed to examine the transformations of mineral phases during roasting process. Kinetic parameters, including reaction apparent activation energy, reaction order, and frequency factor, were calculated by the Doyle-Ozawa and Kissinger methods. Corresponding to the two endothermic peaks, the kinetic equations were obtained.