Melting and solidifying behaviors of the CaO-SiO2-FeO x slags at various oxygen partial pressures

Abstract

The melting and solidifying behaviors of CaO-Si02-FeO x slag with changing oxygen partial pressure are important phenomena to understand the mechanisms and determine the optimum conditions for iron ore sintering process. In the present study, the liquidus for the CaO-Si0 2-FeOx system at 1 523 K with the oxygen partial pressure of 1.8x10-3Pa (1.8x10-8atm) was firstly determined by using chemical equilibration technique. The liquid area was separated into two parts, such as high and low Si02 content regions. The fraction of liquid phase in the solid-liquid two phase region at high FeOx content area was calculated with various CaO/Si02 ratios based on the determined phase diagram. Secondly, the melting and solidifying behaviors of CaO-Si02-FeOx slag with changing oxygen partial pressure were directly observed at 1 573 K by using a confocal scanning laser microscope. The observed melting and solidifying behaviors were compared with the previously measured phase diagrams with various oxygen partial pressures.