Verification of Possibility of Molten Steels Decopperization with ZnAl2O4

Abstract

In the previous research works, ZnAl2O4 material was considered as one of the solutions for the decopperization process of molten steels; up to 33% of decopperization efficiency was reported by utilising the ZnAl2O4 filter. In order to verify the decopperization possibility of ZnAl2O4 materials, iron-based alloys with various copper and carbon contents were interacted with ZnAl2O4 substrates in a heating microscope under an argon gas atmosphere at 1600 °C. Fe-Cu alloys were found to react with the ZnAl2O4 substrate during the interaction process, and a reaction layer with a complex composition around the alloy droplet was formed; however, Cu was not detected in the reaction layer. Cu was later found diffused inside of the ZnAl2O4 substrates. Furthermore, the Cu-Zn compounds were detected when the copper content in Fe-Cu alloys was 10 wt% Cu. After interaction experiments, copper was decreased in all cases. Thereby, the copper evaporation and infiltration into the ZnAl2O4 substrate were considered as the reasons for copper loss. Moreover, oxygen dissolved in melt was found to have a great effect on the copper evaporation process.

Decopperization by Utilization of the Filter

“…The conducted experiments are summarized in Table 20.2. More detailed experimental information including the schematic illustration of the sessile drop method was already reported elsewhere [34].…”

“…Furthermore, a few ppm of oxygen can significantly reduce the surface tension value [37]. Thereby, the effect of oxygen on the free evaporation rate constant of copper from liquid iron was suggested to be expressed by assuming Langmuir's ideal adsorption isotherm: [34,38]…”

“…Fig. 20.2 a Images of Fe-Cu droplet on ZnAl 2 O 4 substrate; b Copper concentration in the cross section from interface to the substrate; c. Microstructure of cross section of the samples[34] …”

“…Fig. 20.3 a Image of Fe-1%Cu-0.5%C with ZnAl 2 O 4 substrate; EDX analysis of newly formed reaction layer on the interface of ZnAl 2 O 4[34] …”