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Processes2026, 14(1), 26;https://doi.org/10.3390/pr14010026 
(registering DOI)
by
  • Jianxin Wang1,2,
  • Liangying Wen1,* and
  • Dong Yue1
  • et al.

Reviewer 1: Anonymous Reviewer 2: Varun Singhal Reviewer 3: Anonymous Reviewer 4: Marina Aleutdinova

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript submitted by the authors provides a sufficiently detailed and clear description of materials related to the production of a critical metal – titan. The research methods employed are conventional and widely used in metallurgical studies.

However, several comments and concerns should be addressed.

 

General Comments:

  1. The introduction would benefit from a more comprehensive discussion of the known characteristics of TiBCS, including a general description of this material, current estimates of accumulated TiBCS, and its annual generation volume.
  2. Section 2.2 should include a clear justification for the selected experimental parameters. In particular, the choice of temperature and the volume ratio of Cl2 to (Cl2+N2) should be explained: are these standard industrial parameters, or were they determined empirically etc. Without such justification, the use of a single experimental condition limits the applicability of the findings.
  3. Many of the results are presented as observational facts without providing sufficient explanation or discussion of the underlying causes.

 

Specific Questions:

  1. The method used to determine the chemical composition presented in Table 1 and Figure 4 should be specified. It is recommended to provide either the measurement range or associated error margins; otherwise, it appears the analysis may have been performed only once.
  2. Section 3.1: Please clarify the formation mechanism of the "amorphous glassy matrix." How confident are the authors in identifying this phase as amorphous? The XRD patterns do not show a halo typical of amorphous materials.
  3. Не понятно, каким образом была отобрана партия для определения размера частиц. Стоит описать метод.
  4. Figure 4b: The meaning of the “quantity/t” values reported for TiBCS and TiET should be explained.
  5. Figure 5: The discussion lacks comments regarding the observed fracture morphology of the particles.
  6. Table 6: The EDS method has limited accuracy for quantifying oxygen and carbon. The authors should clarify whether carbon was included or excluded manually during analysis of individual microstructural components.
  7. In the microstructural description (lines 198–200), the authors refer to "gray-white" and "bright white" particles. These should be clearly marked in the micrographs to avoid misinterpretation.
  8. Lines 212–213: The authors should indicate the titanium-free regions where carbon is said to appear due to the discussed mechanism. How confident are the authors in this interpretation, considering that carbon was previously undetected via EDS? In Figures 7c and 8c, carbon appears to be present in the bright white particles; however, no carbon is visible in the main gray matrix in the elemental distribution maps.
  9. Based on the results from both XRD and MLA, discrepancies in the phase composition are observed. This difference should be explained, or the XRD analysis should be re-examined, as it is known to have limited accuracy. At minimum, the approximate composition of melilite should be provided in Section 3.5.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Comments

  1. Authors should refine the title to better highlight the microstructural evolution obtained in the work.
  2. Quantitative results, such as reduction percentage of TiCxOy after chlorination, should be included by the authors in the abstract.
  3. The authors should clearly specify the statement of research gaps, particularly on titanium phase migration during fluidized chlorination.
  4. Authors should more strongly justify the choice of reaction temperature 500 °C, either through thermodynamic or kinetic reasoning.
  5. Authors reporting fluidization should give full fluidization parameters, including minimum fluidization velocity, bed expansion ratio, and Reynolds number.
  6. Authors should identify the basis used to calculate chlorination rates, specifically if the basis was TiC content or total Ti content.
  7. Authors are recommended to quantify attenuation of the TiC₀.₇₀O₀.₃₀ XRD peaks by means of intensity ratios or other metrics useful for interpretation.
  8. Authors should discuss the kinetic limitations that result in incomplete chlorination of encapsulated TiCxOy and metallic iron despite favorable thermodynamics.
  9. The authors should comment on why encapsulated TiCxOy remains unreacted, considering mass-transfer or diffusion limits.
  10. Authors should more clearly discuss the novelty of this work by comparing findings with previous research on chlorination of Ti-bearing materials.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

I have reviewed the manuscript entitled “Evolution and Migration Behavior of Titanium-Bearing Phase During Low-Temperature Fluidized Chlorination of Carbonized Slag” and find that it requires further development before it can meet the standards of a complete and publishable article. My comments, intended to be constructive, are outlined below:

  • The Abstract contains several long and dense sentences, which makes it difficult to follow. Shorter and clearer phrasing is recommended.
  • At least one quantitative indicator should be added in the Abstract to reflect the main findings, demonstrate the contribution of the work, and highlight the accuracy of the applied methods.
  • Please check the reference numbering; one citation appears as “[11,121,13,14]”, which seems incorrect.
  • The research gap concerning the “lack of systematic characterization of titanium phase migration and evolution” appears only in the final paragraph of the introduction. This section should be strengthened with clearer context and explicit articulation of the gap.
  • Lines 137–138, The reduction in TiC₀.₇₀O₀.₃₀ peak intensity is described qualitatively, so a numerical value or percentage decrease is recommended.
  • The explanation of chlorination selectivity is more in brief. A clearer and more direct linkage to thermodynamic data is recommended to improve readability.
  • Lines 173–175, the term “etching effects” should be clarified. Please indicate whether this is inferred or supported by direct evidence.
  • The statement regarding “comminution caused by particle collisions” is mentioned earlier, but no quantitative evidence is provided. Supporting data or clarification is recommended.
  • The mapping results would benefit from additional quantitative measurements to improve the interpretation.
  • The thermodynamic description is overly brief. Please specify ΔG values, temperature ranges, or reaction pathways to improve clarity.
  • In the Conclusions, please clarify whether the presence of Cl in the observed pores was confirmed through EDS mapping, point analysis, or inferred indirectly.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Dear Authors!

The article by Jianxin Wang et al., "Evolution and Migration Behavior of Titanium-Bearing Phase During Low-Temperature Fluidized Chlorination of Carbonized Slag," contains some data on the particle structure of industrial slag containing titanium. The article is quite worthy of publication in the journal "Processes." However, it is reasonable to make some additions to the paper.

  1. Lines 142-143 ... “The volume-weighted mean diameters (D[4,3]) of TiBCS and TiET are 90.9 μm and 78.0 μm, respectively”. These data are presented in Figure 3. This means that the phrase is redundant and should be deleted.
  2. Fiqure 2 is not clear for what is given and what does the lower XRD mean? What XRD radiation was used?
  3. Lines 163-164 ... This difference clearly indicates that the selective chlorination characteristics of TiC and MFe ... This phrase should have a finish.
  4. Fig. 7 and Fig. 8 - the color for each element should be indicated.
  5. Fig. 11 - TiC + 2 Cl2 = TiCl4 + Cl2. Where did the carbon disappear?
  6. Lines 227, 232, 242, 249, etc. And Fig. 12 - metallic iron is mentioned everywhere. Why is this iron absent from the XRD pattern (Fig. 2) as a crystalline phase? This should be explained.
  7. The particle shapes, their phase and chemical compositions, their ratios, etc., as well as the Gibbs energy for the reactions, were obtained. What is the practical use of all this information? It should be explained how “These results provide mechanistic insights for developing efficient titanium extraction processes from industrial slags” (Lines 24-25). Did the titanium enter quantity increase? Or did energy losses in the process decrease? Or...?

Best regards,

Reviewer…

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I would like to thank the authors for the substantial work undertaken to improve the manuscript in accordance with the comments and recommendations. After the revisions, one question remains: how is the presence of an amorphous phase confirmed if the diffractograms do not exhibit the characteristic halo typically associated with amorphous structures? If such a halo does not appear due to the selected measurement conditions, please clarify this in the manuscript.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

No

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The current version is acceptable for publication. 

Author Response

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Author Response File: Author Response.pdf