Oxidation rate of solid iron using an AR-H ₂O mixture through CaO-SiO ₂-Al ₂O ₃-FeO Slag

The oxidation of solid iron by an Ar-H ₂O mixture through a slag layer was measured as a function of slag composition at 1673 K. A convenient and economical hydrogen analysis system was developed. Since the existence of oxygen is required for the sensor to work properly, the sample gas was mixed with oxygen to maintain a constant partial pressure of 0.21 atm before being introduced into the detection cell. The slag samples were prepared by melting a mixture of CaO, FeO, and SiO ₂ in an alumina crucible at 1 673 K under an Ar atmosphere for 1 h. A solid iron preform, machined on a lathe for a proper fit, was placed at the bottom of the alumina crucible and 20 g of slag was kept in an electric furnace for 30-40 min to attain slag-metal equilibrium under the 1673 K Ar atmosphere. The Ar-H ₂O mixture was then blown onto the slag surface. The partial pressure of water was measured for each Ar flow rate using a gravimetric analysis. The evolution rate increased with an increase in the flow rate and became constant at above 46 cm ³ s ^-1, where the effect of the gas phase mass transfer was eliminated.