Thermodynamic Study of H2-FeO Based on the Principle of Minimum Gibbs Free Energy
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsDear authors,
congratulations on a nice article. I have no comments, but in the attachment I send for illustration the course of the enthalpy change of the considered reaction through the thermodynamic program HSC chemistry.
Yours sincerely
Comments for author File: 
Comments.pdf
Author Response
Dear reviewer,
We would like to thank you for your careful reading, helpful comments, and constructive suggestions, which significantly improved the presentation of our manuscript. We will take full account of the attachment you provided and add this section in the next revision.
Reviewer 2 Report
Comments and Suggestions for AuthorsReviewer’s Comments:
The manuscript “Thermodynamic study of H2-FeO based on the principle of minimum Gibbs free energy” is very interesting work. Studies have shown that the reduction of wustite is the limiting factor in the ironmaking process, whether in hydrogen-based shaft furnaces, hydrogen-rich blast furnace or Smelting Reduction Vessel. The study of the thermodynamic conditions for the reduction of molten wustite by hydrogen is of great significance for the optimization of the ironmaking process, energy saving and emission reduction. Previous studies have mostly focused on the thermodynamic study of the reduction at a lower temperature, but that at a higher temperature between 1650-2000K is not comprehensive and lacks systematic thermodynamic analysis. In this paper, a thermodynamic calculation model for the reduction of molten wustite by hydrogen based on the principle of minimum Gibbs free energy is developed. The enthalpy changes of the reaction at different temperatures and the partial pressure of hydrogen required for the reaction to occur are calculated, and the energy change during the reaction is analyzed. The results show that the partial pressure of hydrogen for the reduction of molten wustite by hydrogen at high temperature decreases from 0.67 at 1650K to about 0.65 at 2000K. However, the following issues should be carefully treated before publication.
1. In abstract, the author should add more scientific findings.
2. Keywords: the synthesized system is missing in the keywords. So, modify the keywords.
3. In the introduction part, the introduction part is not well organized and cited references should cite recently published articles such as 10.1016/j.jallcom.2020.158338, 10.1039/D0RA08573A
4. Introduction part is not impressive and systematic. In the introduction part, the authors should elaborate the scientific issues in the Gibbs free energy research.
5. Thermodynamic data…, The author should provide reason about this statement “FactSage is a common data calculation software for metallurgical disciplines. FactSage holds thermodynamic data for thousands of pure substances and the data provided in FactSage version 8.2 are used in this paper”.
6. The authors should explain regarding the recent literature why “Enter the molecular search condition to obtain various thermodynamic data information for the substance”.
7. Thermodynamic equilibrium diagram. The author should explain the latest literature “The NIST database gives values that also show a decreasing trend, but to a slightly greater extent than the four thermodynamic handbooks mentioned above”.
8. The author should provide reason about this statement, “In practice, the addition of oxygen to the high temperature reduction gas is often used to increase heat and temperature, which makes hydrogen-based shaft furnaces more energy intensive and costly”.
9. Comparison of the present results with other similar findings in the literature should be discussed in more detail. This is necessary in order to place this work together with other work in the field and to give more credibility to the present results.
10. The conclusion part is very week. Improve by adding the results of your studies.
Author Response
Dear reviewer,
We would like to thank you for your careful reading, helpful comments, and constructive suggestions, which significantly improved the presentation of our manuscript. Please check the attachment for the specific revision content.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsReviewer comments on the paper
Thermodynamic study of H2-FeO based on the principle of 2 minimum Gibbs free energy
In my opinion, the authors addressed an interesting fundamental study. The study is well-designed corroborated by adequate analysis and discussions, presenting useful thermodynamics data for the wustite-iron system at high temperatures. The paper, however, needs improvements before being considered for publication.
Following are my comments and mandatory improvements:
1) The authors claimed that the study could directly support the hydrogen blast furnace operation. However, the analysis is too far from the blast furnace conditions even if the blast furnace operation was based on pure hydrogen injection. The authors must discuss in detail the shortcomings of the analysis and show where the theoretical analysis is plausible.
2) Why consider only the wustite-iron reduction step?
3) Equations 7 and 8 are strong simplifications for the analysis. Please discuss the validity of these assumptions.
4) I suggest the authors change all the pair of dependent functions by versus, instead of – (for example H versus T or H(T) instead of H-T)
5) Equation 10 the parenthesis are wrong.
6) The integration of Eq 11 is not straightforward. Please give details of the steps. By the way, equations 13 and 14 should be presented first???
7) Figure 2: What is the reason for the strong difference in the enthalpy function using the factsage database and the others? Explain and discuss the implications of the analysis. Why did the melting point of the iron not affect the others databases?
It is recommended that the authors make a careful check of the word spelling and expressions.
Author Response
Dear reviewer,
We would like to thank you for your careful reading, helpful comments, and constructive suggestions, which significantly improved the presentation of our manuscript. Please check the attachment for the specific revision content.
Author Response File: Author Response.pdf
