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The vaporization of vanadium pentoxide from CaO-SiO2-VOx ternary slags using different gas treatment regimens and parallel vacuum gas extirpation to treat V-bearing slags at 1873 K has been developed in the present study. The novelty of the present study is to monitor the effect of parallel alumina dissolution on the vaporization phenomenon. Vanadium pentoxide has high vapor pressure at the temperatures over 1500 K. When CaO-SiO2-VOx ternary slags, kept in dense alumina crucibles, are injected with oxygen, V2O5 gas bubbles are formed which are forced out by using vacuum extirpation. The vanadium pentoxide could be then collected in the exhaust gases. The mechanism of the process phenomenon is described as the formation of V2O5 gas phase resulting from the oxidation of the lower-valent oxides present in the slag. This gas phase would form microbubbles in the molten slag bulk phase due to low surface tension between the gas phase and the slag, thereby increasing the contact surface. At the same time, the crucible material would dissolve in the slag causing an increase in the slag viscosity. Due to the high slag viscosity of the bulk slag, these microbubbles formed would have difficulty in coalescing and reaching the slag surface. The escaping of the bubbles into the gas phase is enabled by the vacuum extirpation.

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.

Alumina refractories and ceramics are extensively applied in the steelmaking field due to their excellent properties, such as chemical resistance and high wear resistance at high temperature. [1] Besides this, the addition of graphite significantly improves the thermal shock resistance of alumina. Thanks to these properties, the application spectrum of Al 2 O 3 -C materials became very wide-from ladle refractory to submerged nozzle and filters. [2][3][4][5] Khanna et al. [6,7] investigated the interaction between pure Al 2 O 3 , Al 2 O 3 -12.9 mass % C, and molten iron using the sessile drop method at 1550 C between 15 min and 3 h. The authors reported a strong interaction between Al 2 O 3 ÀC and molten iron including COÀgas evolution, extensive iron penetration into the substrate, and refractory degradation, Fe 3 Al formation at the iron refractory interface, and Al 2 O 3 whiskers formation. In contrast, no Al 2 O 3 whiskers formation and penetration of molten iron into the refractory was found in investigations with pure Al 2 O 3 and molten iron. In addition, when a blank Al 2 O 3 -C sample was heated without the presence of molten iron under the same experimental conditions, no Al 2 O 3 whiskers formation could be detected. Khanna et al. [6,7] explained these phenomena through the carbothermic reduction of Al 2 O 3 and dissolution of the reduced aluminum into the liquid iron. Similar investigations with identical results were achieved by Ikram-Ul-Haq et al. [8] However, in earlier publications, the carbothermic reduction of alumina was reported under low pressure (0.08-0.2 atm) with the presence of Sn and Cu as a metallic solvent (from 1700 C to 1850 C) [9] or under vacuum conditions. [10] Nevertheless, the aforementioned explanations for carbothermic alumina reduction at low temperature were not supported by other researchers. [11] If equilibrium concentrations of Al and oxygen in Fe liquid are low, carbothermic reduction is not possible. Zienert et al. [11] conducted a thermodynamic simulation of the Al 2 O 3 ÀC/ Fe system to investigate the process of dissolution of Al and O in Fe liquid in the presence of C across the interface at the conditions of Khanna's [6] investigation. The reaction at every step in this simulation involved the dissolution of small amounts of alumina in liquid iron and the reaction of dissolved oxygen with carbon to CO formation. The amount of dissolved alumina in the simulation was defined from calculated molar densities, the assumed penetration rate, and the contact area and was assumed constant during the simulation. This continuous dissolution of alumina led to pick-up of aluminum in molten iron up to 9.75 at% in 3 h.Wei et al. [12] investigated the interaction between Al 2 O 3 ÀC and Fe in Al 2 O 3 ÀC crucible at 1600 C under argon atmosphere. Yan et al. [13] reported that the aluminum-bearing volatile species released strongly in the Al 2 O 3 ÀCÀFe system in the temperature range 1500-1520 C reacted with iron, which led to the formation of hercynite whiskers on the surface of a...

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