Reaction Behavior and Transformation Path of Zinc in the Heating-Up Zone during Sintering Process

Abstract

Iron ore sintering is a simple and sustainable way to treat zinc-bearing secondary resources. In this paper, the reaction behavior of zinc was studied by combining thermodynamic calculation and simulation tests under sintering temperature and atmosphere. The evolution law of Zn-containing phases during the heating process was also revealed. The results showed that Zn-containing substances were mainly converted to ZnO when the temperature reached 700 °C in the pre-drying zone, and ZnO started to combine with Fe2O3 to form ZnFe2O4 when the temperature reached 800 °C in the combustion zone. ZnFe2O4 remained stable at 1300 °C, and did not change in the atmosphere with low CO concentration. In conventional sintering conditions, the removal rate of zinc was about 5 wt%, zinc was mainly converted to ZnFe2O4 and stuck in the sinter. Therefore, to meet the zinc amount of the blast furnace load, pretreatment of raw materials or ore matching to control zinc content is necessary.