Ferrous oxide activity has been determined in titania rich slags. Molten synthetic slag mixtures of the ternary systems FeO-TiO₂- SiO₂ and FeO-TiO₂-CaO and of the system FeO-TiO₂-SiO₂ containing MnO and CaO at constant levels of each have been investigated. The slags were contained in iron crucibles and were equilibrated for four hours at 1475°C or 1470°C with gas mixtures containing CO₂, H₂, and argon of varying oxygen potentials. The equilibration technique made use of the equilibrium reaction: - Fe (solid) + ¹/₂ O₂ (gas) = FeO (slag). Each gas mixture used had an oxygen potential corresponding to a certain ferrous oxide activity in the slag and after equilibration the final chemical analysis of the slags gave the compositions having this particular ferrous oxide activity. In the course of determining the activity in the ternary systems, the binary systems FeO-SiO₂ and FeO-CaO were investigated at 1475°C and 1470°C respectively. The ferrous oxide activities determined had a satisfactory agreement with other investigators of these systems. Silica activity was calculated by Gibbs-Duhem equation and calcium oxide activity was calculated by both Gibbs-Duhem equation and regular solution model. In the ternary system FeO-TiO₂-SiO₂ at 1475°C, FeO isoactivity curves are bowed towards FeO corner and this was related to the miscibility gap in the binary system TiO₂-SiO₂ which show that the two liquid oxides are incompatible and must have a positive deviation from ideality. Ferrous oxide activity in this system was compared to MnO activity in the system MnO-TiO₂-SiO₂ and the comparison showed that MnO have lower activity than FeO. Silica activity was calculated by Gibbs-Duhem equation. FeO iso-activity curves in the system FeO-TiO₂-CaO at 1470°C are bowed away from FeO corner. The formation of a series of interoxide compounds in the phase diagram of CaO-TiO₂ explain the increase in FeO activity with the addition of CaO to FeO-TiO₂ binary or vice versa. TiO₂ and CaO activities were calculated by Gibbs-Duhem equation and regular solution model. Basic oxide additions to the ternary FeO-TiO₂-SiO₂ increased FeO activity. Increasing MnO additions from about 8 mole % to about 24 mole % Increased FeO activity but had no effect on the direction of bowing of the curves. Increasing CaO additions reversed the direction of bowing of the iso-activity curves. For all TiO₂ : SiO₂ ratios the addition of 16.1 mole % CaO Increased FeO activity more than the same addition of MnO.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:446694 |
| Date | January 1977 |
| Creators | Abdelkarim, O. I. H. |
| Publisher | University of Strathclyde |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21696 |
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