Oxidative Roasting of Low Grade Zinc Sulfide Concentrate from Gagok Mine in Korea

A new process for utilizing low grade zinc sulfide concentrate containing a large amount of iron as a zinc and iron resource has been developed in Korea. The process largely consists of oxidative roasting and reduction-volatilization processes. In this process, zinc is recovered as zinc oxide form in the gas phase and iron is concentrated as partially reduced iron oxide compounds in the residue phase. In the present work, a kinetic study on the oxidative roasting of low grade zinc sulfide concentrate rich in iron obtained after several mineral separation processes at Gagok mine in Korea was experimentally investigated. The experiments were carried out to understand the oxidative roasting process of the zinc concentrate over a temperature range of 998 to 1073 K under air using a thermogravimetric method. The oxidative roasting rate of the zinc concentrate was found to be relatively fast under the whole temperature range and almost 95% of sulfur contained in the concentrate was removed after the oxidative roasting at 1073 K for 20 min. Sulfur removal ratio as a function of time has been analyzed by using a spherical shrinking-core model. [doi:10.2320/matertrans.M2010045]