Fluidized bed roasting of micro-pelletized zinc concentrate: Part I– Pellet strength and roasting kinetics

Zincor, a zinc refinery located in South Africa, utilizes oxygen enrichment in its fluidized bed roasting process to enhance the oxidation of zinc concentrate. This study aims to investigate the impact of using up to 26% O2-enrichment on the roasting kinetics and pellet strength of zinc concentrate. A series of experiments were conducted to evaluate the phase transformation processes occurring during the reaction of ZnS to ZnO under varying particle sizes and O2 enrichment levels. The methodology involved monitoring the changes in the physical characteristics of the pellets, including strength and attrition resistance, as well as the oxidation rate of the concentrate. The results indicate that oxygen enrichment significantly accelerates the oxidation kinetics, allowing for increased feed rates without compromising the flow rate of the fluidizing air. Furthermore, it was observed that while larger pellets can improve throughput, they require precise control due to longer conversion times and potential challenges with pellet stability. This research contributes to optimizing the roasting process at Zincor and potentially improving overall productivity in zinc processing facilities.