PONE-D-21-17754

Distribution of Spontaneous Combustion three zones and Optimization of Nitrogen Injection Location in the Goaf of a fully Mechanized top Coal Caving Face

PLOS ONE

Dear Dr. qi,

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Academic Editor

PLOS ONE

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"The National Natural Science Foundation of China (Grant: 51274113);

Key special-funded projects of the State key R & D program (2018YFC0807900)"

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 YES"

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Comments to the Author

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Dear editor and author,

Through reading " Distribution of Spontaneous Combustion three zones and Optimization of Nitrogen Injection Location in the Goaf of a fully Mechanized top Coal Caving Face ", it is considered that aiming at the problem of nitrogen waste caused by experience setting of nitrogen injection position in goaf residual coal spontaneous combustion, this paper uses COMSOL multiphysics 5.3 software to study the distribution law of oxidation spontaneous combustion zone in goaf under different nitrogen injection position, which has certain engineering application value.

However, there are still some problems to be discussed:

1.What is the innovation and contribution of the thesis work? Innovation is the basic condition of thesis recruitment and publication.

2.It is mentioned in this paper that two-dimensional model should be used, why not use three-dimensional model? What are the advantages of a two-dimensional model?

3. What is the basis for determining the upper and lower limits of the oxidation temperature rise zone by the isoline of 0.004 m·s-1 wind speed and 8% oxygen concentration in the numerical simulation?

4. The actual recovery speed of 2.5 m/d cannot ensure the safe recovery of the working face, using nitrogen injection can solve this problem. Why not consider other solutions, such as increasing recovery speed?

5. Due to the compressibility of goaf fluid, there will be energy exchange in the process of fluid compression, which leads to the fluid flow can not meet the momentum conservation equation and continuity equation. Is the compressibility of fluid considered in this paper?

6.The three zone distribution of spontaneous combustion in goaf mentioned in this paper is only applied to Jinniu coal mine. Are the results and data universal and suitable for popularization and application?

7.Is the result of field engineering test scientific? Whether it is consistent with practice or supported by other literature.

8.Most of the references in this paper are domestic literature, and the papers of foreign journals are rarely cited.

Reviewer #2: The wide application of fully mechanized top coal caving technology improves the production efficiency of the mine and the advancing speed of the working face. Still, it also leads to increased air leakage intensity in the goaf, more residual coal, and other problems. It increases the probability of spontaneous combustion of residual coal in the goaf. Therefore, in this paper, the research on nitrogen injection technology for fire prevention and extinguishing in the goaf has particular engineering application value.

After modification, the paper is acceptable, and the detailed comments are as follows.

1. Why is it proposed in 1.2 goaf spontaneous combustion "three zones" field monitoring. However, in the numerical simulation results of 4.1, The lower limit of the oxidation temperature rise zone is determined by the contour of the wind speed of 0.004 m/s, not the oxygen concentration. The authors did not analyze the application differences between field monitoring and numerical simulation.

2. Through comparative analysis, it is concluded that the field measurement of the maximum width of the oxidation spontaneous combustion zone is consistent with the numerical simulation results. The authors mentioned that "1303 fully mechanized top coal caving face has been successfully pushed forward for more than 600 meters, and there is no spontaneous combustion of residual coal in the goaf", but should analyze the effect of nitrogen injection in more detail. Please explain how the paper highlights the novelty and practicality of the research results.

3. In the numerical simulation of the distribution of spontaneous combustion "three zones" in goaf, please explain the source of the simplified model and the scientific basis for the simplified process. If so, please describe and quote relevant literature.

4. Explain the data source of Figures 2, 5, and 7, please. Where are the data sources of figures 2, 5, and 7?

5. Please explain why the width of the three belts on the inlet side is more significant than that on the return side.

6. Whether the advancing speed of the working face has an impact on the three zones and whether the author considers it or not.

7. In this paper, the measured temperature of the air inlet is 18.6 ℃. The temperature has a significant influence on the flow process of underground fluid. Is there any influence on the spontaneous combustion of three zones of goaf when the temperature changes in the numerical simulation?

8. There is almost no reference to foreign-related literature in the paper. Is there no related research in foreign journals? The authors should add foreign scholars appropriately. It is better to add the relevant research results in recent years.

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Reviewer #1: No

Reviewer #2: No

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PONE-D-21-17754R1

Distribution of Spontaneous Combustion three zones and Optimization of Nitrogen Injection Location in the Goaf of a fully Mechanized top Coal Caving Face

PLOS ONE

Dear Dr. qi,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Sep 24 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Dragan Pamucar

Academic Editor

PLOS ONE

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Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: (No Response)

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: (No Response)

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: (No Response)

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: (No Response)

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: (No Response)

Reviewer #2: (No Response)

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The capitalization in the title of the thesis is wrong, it is recommended to make the following changes: Distribution of Three Spontaneous Combustion Zones and Optimization of Nitrogen Injection Sites in the Goaf of a Fully Mechanized Carving Face

Reviewer #2: (No Response)

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Reviewer #1: No

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Distribution of Spontaneous Combustion three zones and Optimization of Nitrogen Injection Location in the Goaf of a fully Mechanized top Coal Caving Face

PONE-D-21-17754R2

Dear Dr. qi,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Dragan Pamucar

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: (No Response)

Reviewer #2: (No Response)

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No