Densities of Melts in the FeO–Fe₂O₃–CaO and FeO–Fe₂O₃–2CaO·SiO₂ Systems

抄録

The densities of melts in the systems FeO–Fe₂O₃–CaO and FeO–Fe₂O₃–2CaO·SiO₂ have been measured under controlled oxygen partial pressures from the liquidus temperature to 1873 K by using the Archimedean method. The molar volumes of melts in the ternary system FeO–Fe₂O₃–CaO satisfy the additive rule. The molar volume of hypothetical liquid lime in iron oxide melts shows very good agreement with that estimated from CaF₂–CaO melts and from SiO₂–CaO melts. The densities of the FeO–Fe₂O₃–CaO melts, ρ (kgm⁻³) can be reproduced to within ±0.5% by the following equations:
10⁵⁄ρ=
(1⁄2.676)×(mass%CaO)+(1⁄4.624)×(mass%FeO)+(1⁄4.298)×(mass%Fe₂O₃) (at 1673 K)
(1⁄2.664)×(mass%CaO)+(1⁄4.588)×(mass%FeO)+(1⁄4.259)×(mass%Fe₂O₃) (at 1773 K)
(1⁄2.654)×(mass%CaO)+(1⁄4.548)×(mass%FeO)+(1⁄4.221)×(mass%Fe₂O₃) (at 1873 K)
For the melts in the system FeO–Fe₂O₃–2CaO·SiO₂, the molar volumes do not satisfy the simple additive rule. Increase of dicalcium silicate content and ferrite ions in the melt may contribute to polymerization of silicate ions, and it results in a positive deviation from the additive rule in volume. A liquid miscibility gap was observed in the system FeO–Fe₂O₃–2CaO·SiO₂.