Metallurgical Transactions B

, Volume 6, Issue 4, pp 495–501 | Cite as

A criticism of the Flood-Grjotheim ionic treatment of slag-equilibria

  • John F. Elliott
  • David C. Lynch
  • Tracy B. Braun
Physical Chemistry


The analysis by Flood and Grjotheim1 of the equilibria between a metal and a fused slag utilizes the ionic behavior of the slag or salt, and it employs a reversible thermodynamic cycle. However, in the original analysis there appears to be an error in the use of free energy. A corrected treatment has been developed which involves a modest change and simplification in the original formulation. The revised analysis shows the importance of the thermodynamic behavior of ionic species in the slag, which may be nonideal. Data from the literature on slag-metal equilibria, for example:
$$\left[ {Fe^{2 + } } \right] + \underline {Mn} = Fe\left( l \right) + \left[ {Mn^{2 + } } \right]$$
, are analyzed by the new formulation to obtain expressions for ratios of activity coefficients such as (γS2−/γO2−), (γMn2+/γFe2+) and [(γPO 4 3− )2/(γO2−)3] in terms of slag composition, the last two having been found to depend strongly on the oxygen-ion content of the slag.


Activity Coefficient Liquid Iron Standard Free Energy Basic Slag FeF2 


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Copyright information

© The Metallurgical Society of AIME 1975

Authors and Affiliations

  • John F. Elliott
    • 1
  • David C. Lynch
    • 1
  • Tracy B. Braun
    • 2
  1. 1.Massachusetts Institute of TechnologyCambridge
  2. 2.Kennecott Research Center, Metal Mining DivisionKennecott Copper CorpSalt Lake City

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