Study of the Crystallographic Distortion Mechanism during the Annealing of Kaolinite

Round 1

Reviewer 1 Report

The content of this manuscript has some significance. The mechanism of crystal structure change during kaolinite annealing is characterized by different experiments. The experimental results are good, but there are several problems that need to be noted.

1.The abstract needs to be rewritten, which does not reflect the main connotation of the research content well.

It is not necessary to be related to gangue in coal. Although kaolinite is the main material composition of gangue, the degree of crystallization is generally low, and the practical application does not necessarily support the experimental results in this paper. The importance of research can be emphasized from other aspects, such as material modification, which may be of more practical value. Data from TableA1 show that the sample is almost equivalent to high-purity kaolinite mineral, and such purity kaolinite is rarely seen in gangue.

2.The sample collection and processing process is not detailed enough. It is not clear where and how the samples be sampled and what processing had be done. Is the original sample mineral or rock?

3.Sample characteristics used in different experimental methods should also be briefly described.

4. Where does the formula used in 4.2.5 XAS Calculation come from? There are no references.

5.Figure.4. How is the change of crystal structure deduced? It is not stated.

6.Figure6b is slightly inconsistent with the description in the MS, please check it carefully.

7.There is almost no mention of coal or gangue in the conclusion, which is why the preamble I mentioned earlier makes no sense.

Other problems be listed in the MS.

Comments for author File: Comments.pdf

Author Response

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Reviewer 2 Report

This is a detailed study describing mechanism of crystallographic distortion of kaolinite during thermal treatment, which is within the scope of Minerals journal. The manuscript provides results of modern instrumental techniques (XAFS, XRD, FTIR, TG/DSC etc.) that are undoubtedly interesting (and useful for modern intelligent photoelectric separation technology) – so there is a need to publish the study. Nevertheless, major revision of the paper is needed namely in terms of its technical quality and readability.

Specific comments and suggestions

Title, abstract and keywords are good.

Introduction. I suggest revision of the first two paragraphs (lines 28-40) – they could be joined as they are similar. And, as Minerals is multidisciplinary journal with readership in various research branches, it could be helpful for the readers to briefly explain the principle of the intelligent photoelectric coal separation as a modern technology. It is also essential for quick understanding of the significance and practical utilization of the results presented in the manuscript. Knowledge gaps in this area could be clearly joined with the objectives of the study, which could be also mentioned (within a couple of sentences) in the Conclusion.

Section 2.5. – XAS calculation. Equations and formulas mentioned there should be mentioned (introduced) in the corresponding text. Where appropriate, the dimensions (units) of the variables could be provided.

3. Results and discussion. Please check and correct the numbering of the subsections as now they are numbered as: 3.1., 3.2., 3.3., 3.3., 3.2. and 3.5. And, Figure 3 mentioned in the text (line 237) should be Figure 5. So please check the overall manuscript for other similar mistakes.

Fig. 8 is very illustrative so there is a pity that the labels inside are too small to be easily readable.

As for the readability, I have also one general suggestion regarding the figures captions. Even if all measurements conditions and all used symbols and abbreviations have been described in the text, typical busy reader seeing only the diagrams and photos will not understand what is P1, P2, P3 etc. Captions of XRD patterns are better (with more details), perhaps, in addition to time, the temperature could be mentioned as well (in my opinion it is a key factor).

 

Author Response

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Reviewer 3 Report

It is a repetitive paper on the crystallography of kaolinite which has been highly developed for a long time.

 It must be corrected:

Line 81: indicate the mineralogy of the area. It may not be a kaolinite but a kaolin

Line 220: Indicate that it is Mp 541152

Line 274: calculation?

Line 276: what is FEFF9

In Figure 5 the amorphous materials have not been calculated, in reality it is not a kaolinite but rather a kaolin, as previously assumed. A Rietveld XRD calculation must be performed to view amorphous materials.

 

Table A1: somewhere it should be indicated that the compositions are measured in %.

Author Response

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Round 2

Reviewer 2 Report

Manuscript has been revised according to reviewers´ comments.

Introduction has been revised and is now more clear and easy to follow.

Numbering of sections has been corrected.

Font size used in Fig. 8 is now bigger and readable.

Figures captions are now more specific.

Now the revised version can be accepted for the publication.

Reviewer 3 Report

The new version has improved a lot and has cleared up doubtful issues.