Industial EAF slag was anlysed using WD-XRFS, result shows Iron oxide as Fe2O3 and also the slag was analysed using XPS, there we got the peaks for both FeO and Fe2O3. According to Ellingham diagram, FeO should be stable at the steelmaking temperature, so my question is, in which form the iron oxide is there in EAF slag?
It would depend upon pet coke injection. More will be pet coke injection rate, lower will be Fe2O3.
rachappa.kadli Kadli Sir If I May ask, In what basis you are saying this?
Ashok Kamaraj So is there any way to calculate the quantitative fraction of both the oxides in EAF Slag?
Ziwen Yan Sorry, I didn't get the reason why FeO would be there at steelmaking temperature, if you kindly explain?
Nadiya Sadeek al Saffar Can you please explain why there will be only FeO at process temperature in EAF Slag?
I think that, from the standpoint of thermodynamics, this is depends basically on the chemical composition of the slag, and on the O2 partial pressure. The amounts of Fe+2 and Fe+3 can be calculated with any software for chemical thermodyn. Like eg. Factsage.
You are welcome. Of course, the pO2 may be also (indirectly) fixed through the contact with some other phase, e.g. a gas phase, the steel melt etc.
J. Rezende Sir how do I fix the pO2 in the equilib module when I want to see the slag composition at equilibrium in FactSage?
Hello Sumanta Maji,
there is an example for this in FactSage. Please find it on the Home window of Factsage, in the upper menu bar, under Information->FactSage Applications -> Factsage ferrous processing: Applications I, page 26. What you basically need to do is:
a) include FactPS as a database
b) on the menu window, include the gas phase as a compound species
c) right click with the mouse on "gas" (on the menu window), then, when the list of species appear, right click on "+" next to O2 and proceed according to the attached picture to fix pO2
J. Rezende Thank you very much sir. I have performed the calculation as stated and also gone through the slides and got the desired results. Thank you once again for the assistance.
Sumanta Maji, actually you won't find Fe2O3 and possibly even not FeO, as these are mineral phases. On the contrary, you will find Fe2+ (like in FeO) and Fe3+ (like in Fe2O3) in different mineral compositions in combination with the other elements of the slag (Ca, Si, Al, Mg, etc.).
The oxidation state (2+ or 3+) is indeed, as my dear friend J. Rezende explained, depending on the oxygen partial pressure. You achieve this via the oxygen input, but have to consider "capturing" the O2 with carbon injections and the burning of natural gas. The best would be to determine "Fe total", "Fe metallic" and "Fe3+" (with wet chemistry). You can then calculate Fe2+.
To come back to your question: FeO and Fe2O3 are both possible.
Additional note: One mineral phase even combines them, which is Fe3O4 (magnetite), also written as Fe(2+)Fe(3+)O5.
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