HYDROGEN REDUCTION AND MICROSTRUCTURAL CHANGES OF ISF SINTER

The reduction rate and microstructural changes of imperial smelting fu rnace (ISF) sinter have been investigated by means of thermogravimetri c analysis, X-ray diffraction (XRD), scanning electron microscope (SEM ), energy dispersive analysis of X-ray (EDAX) and optical microscope. It is demonstrated that the overall reaction rate of the reduction is influenced by temperature and hydrogen partial pressure in H-2/N-2 gas mixtures. There are two distinct zones observed in the partially redu ced sinter. The reduction of zincite proceeds predominantly in a narro w range between the two zones, while the reduction of lead oxide and s ilicate takes place throughout the sinter. The differences between zin cite and lead oxide or silicate in reducibility are analysed by thermo dynamics. The phase transformations and microstructural changes occurr ing during the reduction process are discussed.