In the present work, the reaction between a molten iron drop and dense alumina was studied using the X-ray sessile-drop method under different oxygen partial pressures in the gas atmosphere. The changes in contact angles between the iron drop and the alumina substrate were followed as functions of temperature and varying partial pressures of oxygen in the temperature range 1823 to 1873 K both in static and dynamic modes. The results of the contact angle measurements with pure iron in contact with dense alumina in extremely well-purified argon as well as under different oxygen partial pressures in the gas atmosphere showed good agreement with earlier measurements reported in the literature. In the dynamic mode, when argon was replaced by a CO-CO 2 -Ar mixture with a well-defined in the gas, the contact angle showed an initial decrease followed by a period of nearly constant contact angle. At the end of this period, the length of which was a function of the imposed, a further steep decrease in the contact angle was noticed. An intermediate layer of FeAl 2 O 4 was detected in the scanning electron microscope (SEM) analysis of the reacted substrates. An interesting observation in the present experiments is that the iron drop moved away from the site of the reaction once the product layer covered the interface. The results are analyzed on the basis of the various forces acting on the drop.

Dynamic X-ray imaging of a metal droplet in a slag phase is an elegant way to monitor the rate of the interfacial reactions. In an attempt to follow the kinetics of dephosphorization, the changes in the shape of the sessile drop of molten iron with 0.1 wt% P immersed in a slag kept in MgO crucibles were recorded as a function of time. The slag had an initial composition 40 wt% CaO, 30 wt% SiO 2 and 30 wt% Fe 2 O 3 . While in a set of runs, solid iron was added to the molten slag, the sequence was reversed in others, where a pellet of the slag was added to the molten iron. In the former case, it was found that after 10 s, the drop flattened and the contact angle, θ was well below 90 • , indicating a significant increase in the contact area. Beyond 250 s, the contact angle showed a gradual increase. In the second series, where the slag was added to the metal, the contact angle remained high throughout the dephosphorization reaction, indicating a rapid mass transfer of phosphorus.Similar application in the field of copper metallurgy, where the transfer of arsenic and antimony from copper metal to molten Na 2 CO 3 was studied, confirm that this technique is very useful in understanding the mechanisms of the slag-metal reactions.

In the present work, the change of the interfacial tension at the slag-metal interface for sulfur transfer between molten iron, slag, and gas phases was monitored by X-ray sessile drop method in dynamic mode in the temperature range of 1830 to 1891 K. The experiments were carried out with pure iron samples immersed partly or fully in the slag phase. The slag consisted of 30 wt pct CaO, 50 wt pct Al 2 O 3 , and 20 wt pct SiO 2 (alumina saturated at the experimental temperatures) with additions of FeO. Metal and slag samples contained in alumina crucibles were exposed to a CO-CO 2 -SO 2 -Ar gas mixture with defined oxygen and sulfur partial pressures, and the change of the shape of the metal drop was determined as a function of time. The equipment and the technique were calibrated by measurements of the surface tensions of the pure Cu, Ni, and Fe containing two different amounts of dissolved oxygen. A theoretical model was developed to determine the sulfur content of the metal as a function of time on the basis of sulfur diffusion in the slag and metal phases as well as surface tension-induced flow on the metal drop surface. Attempts were made to compute the interfacial tensions on the basis of force balance.

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The objectives of the present investigation were: (i) to determine whether dephosphorisation was The effect of interfacial tension on the kinetics of accompanied with a marked decrease in interfacial the dephosphorisation of iron has been tension investigated. X-ray monitoring of the shape of a (ii) to investigate whether this influenced the kinetics of molten iron droplet in liquid slag showed that there the dephosphorisation reaction. was a marked reduction in the interfacial tension Consequently, measurements of the kinetics of dephosc ms during periods of rapid mass transfer and an phorisation of liquid Fe-P alloys were made, and the increase in c ms as the mass transfer process slowed reaction was followed by monitoring the shape of a sessile down, similar to that observed for desulphurisation.drop of molten iron in molten slag. The dephosphorisation kinetics was found to be first order with respect to phosphorus in the liquid iron and implied that, for the system studied, mass EXPERIMENTAL transfer of phosphorus in the slag phase is the rate Kinetic measurements controlling step. I&S/1397The measurements were carried out using electrolytic iron to which FeP was added to achieve a starting metal