Eco-Friendly Mining Practices: Field Test of Phosphogypsum Filling Based on Slag Powder in Dayukou Phosphate Mine

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Report on: Manuscript #: sustainability-3540176-peer-review-v1

Title Field test of phosphogypsum filling based on slag powder, March. 8, 2025

 

Thanks for your kind invitation to review this manuscript.

 

This research focuses on the extensive on-site experiments conducted at the Dayukou phosphate mine, China to fill the voids in the 1# and 2# test ore pillars. The research is well organized, clear goals, results and illustrated Figs.   

However, there are some critical comments should be addressed.

- 1. Introduction: best to short

- L. 283: 3.5: Put this discussion in a separate section  (e.g., 4) and discuss your output in detail and support it by references. Discus you’re obtained data with similar well published references.

- a lot of spaces should be added examples in L. 33, 36, 223, 242, 244, 267, 269, 267, 269, 284, 288, etc.

- Some references should be added to support your ideas: L. 47, 99, 193,

Tables: add: Results of …. In all tables.

Table 1 Main chemical components of the slag powder (SP), phosphogypsum (PG) correct to : Table 1 Reults of Main chemical components (Wt. %) of the slag powder (SP), phosphogypsum (PG)

Change / to – in table 1

1. 160: Fig. 2 : add: diagram
2. 161: correct to: Table 3 Reasults of Consumption and Cost Statistics for Various Backfill Wall Materials

L.191: delete and discussion, please put the discussion as a separate section (e.g., 4)

Fig. 3, 5: add photographs showing …

Finally, this paper is suitable for publication in the sustainability Journal after minor modified.   

 

This research focuses on the extensive on-site experiments conducted at the Dayukou phosphate mine, China to fill the voids in the 1# and 2# test ore pillars. The research is well organized, clear goals, results and illustrated Figs.   

However, there are some critical comments should be addressed.

- 1. Introduction: best to short

- L. 283: 3.5: Put this discussion in a separate section  (e.g., 4) and discuss your output in detail and support it by references. Discus you’re obtained data with similar well published references.

- a lot of spaces should be added examples in L. 33, 36, 223, 242, 244, 267, 269, 267, 269, 284, 288, etc.

- Some references should be added to support your ideas: L. 47, 99, 193,

Tables: add: Results of …. In all tables.

Table 1 Main chemical components of the slag powder (SP), phosphogypsum (PG) correct to : Table 1 Reults of Main chemical components (Wt. %) of the slag powder (SP), phosphogypsum (PG)

Change / to – in table 1

1. 160: Fig. 2 : add: diagram
2. 161: correct to: Table 3 Reasults of Consumption and Cost Statistics for Various Backfill Wall Materials

L.191: delete and discussion, please put the discussion as a separate section (e.g., 4)

Fig. 3, 5: add photographs showing …

Finally, this paper is suitable for publication in the sustainability Journal after minor modified.   

Kind regards

Author Response

Dear Reviewer：

Thank you for your letter and for the reviewers' comments concerning our manuscript entitled “Field test of phosphogypsum filling based on slag powder”(ID:sustainability-3540176). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. The main corrections in the paper and the responds to your comments are as flowing：

Reviewer 1:

Response to comment: 1. Introduction: best to short- 1. 

Thank you for your suggestion,the introduction section has been shortened

Response to comment: 2. L. 283: 3.5: Put this discussion in a separate section  (e.g., 4) and discuss your output in detail and support it by references. Discus you’re obtained data with similar well published references..283： 3.5：

Thank you for your guidance,we have completed the modification of this part.L. 258-282,We have listed the discussion in separate sections and verified that the results meet the relevant specifications in China

Response to comment: 3. a lot of spaces should be added examples in L. 33, 36, 223, 242, 244, 267, 269, 267, 269, 284, 288, etc.

We are sorry for these errors, full text spelling has been checked and spaces have been added as required in L.31,34,249,250,269,272,295,296,298,315,316,320,etc.

Response to comment: 4.Some references should be added to support your ideas: L. 47, 99, 193,

We referred to the actual trial report,and some of the data are derived from the field experiments.

Response to comment: 5.Tables: add: Results of …. In all tables.

Table 1 Main chemical components of the slag powder (SP), phosphogypsum (PG) correct to : Table 1 Reults of Main chemical components (Wt. %) of the slag powder (SP), phosphogypsum (PG)

Change / to – in table 1

160: Fig. 2 : add: diagram

161: correct to: Table 3 Reasults of Consumption and Cost Statistics for Various Backfill Wall Materials

L.191: delete and discussion, please put the discussion as a separate section (e.g., 4)

Fig. 3, 5: add photographs showing …

Thank you for your guidance, and we have completed the modification as required.Pictures with unclear meaning were removed.

Special thanks to you for your good comments. We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. And here we did not list the changes but marked in red in revised paper.

Once again, thank you very much for your comments and suggestions.

 

Reviewer 2 Report

Comments and Suggestions for Authors

Phosphogypsum is a type of bulk solid waste, and its reuse has always been a research hotspot. This paper, taking the reuse of phosphogypsum from the Dayukou phosphate mine as its background, conducts on-site pilot experiments based on the hydration mechanism of phosphogypsum, as well as the properties of cement and slag micro-powder. It investigates the strength of ore pillars, the changes in stress in the mining area, and the content of leached substances. This research is of great significance for the utilization of slag. The paper demonstrates good innovation and engineering application value and aligns well with the research interests of this journal. Therefore, it is recommended to accept the paper after revision. The following suggestions are provided for the authors to consider:

（1）The introduction of experimental raw materials in Section 2.2.1 is insufficiently detailed. It is recommended to further elaborate on the characteristics of the raw materials to provide readers with a clearer reference.

（2）The paper contains numerous photos of the engineering site. Given their limited relevance to the core research content, it is suggested to selectively reduce the number of on-site photos to enhance the focus of the paper.

（3）Section 2.1 mentions the goaf (mining void). It is recommended to include a schematic diagram of the goaf structure, complete with corresponding dimensions, to visually illustrate this concept.

（4）In the Results and Discussion section, the authors still provide detailed descriptions of equipment and materials. It is suggested to move these descriptions to Chapter 2 (Experimental Methods) and focus solely on analyzing and discussing the experimental results in the Results and Discussion section.

（5）It is recommended that the authors visualize key data and experimental results through graphs or charts to facilitate a more intuitive understanding for readers.

Author Response

Dear Reviewer：

Thank you for your letter and for the reviewers' comments concerning our manuscript entitled “Field test of phosphogypsum filling based on slag powder”(ID:sustainability-3540176). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. The main corrections in the paper and the responds to your comments are as flowing：

 

Response to comment:1.The introduction of experimental raw materials in Section 2.2.1 is insufficiently detailed. It is recommended to further elaborate on the characteristics of the raw materials to provide readers with a clearer reference.

Relevant instructions have been added in the L109, 110, 111.

Response to comment:2.The paper contains numerous photos of the engineering site. Given their limited relevance to the core research content, it is suggested to selectively reduce the number of on-site photos to enhance the focus of the paper.

Thanks for your suggestion, the picture has been modified.

Response to comment:3.Section 2.1 mentions the goaf (mining void). It is recommended to include a schematic diagram of the goaf structure, complete with corresponding dimensions, to visually illustrate this concept.

I are very sorry, the authors think this picture is not related to phosphogypsum filling and will not be added.

Response to comment:4.In the Results and Discussion section, the authors still provide detailed descriptions of equipment and materials. It is suggested to move these descriptions to Chapter 2 (Experimental Methods) and focus solely on analyzing and discussing the experimental results in the Results and Discussion section.

Thanks for your suggestions, the discussion section is listed separately as part 4.

Response to comment:5.It is recommended that the authors visualize key data and experimental results through graphs or charts to facilitate a more intuitive understanding for readers.

Thank you for your advice.The data in the paper were not been visualized,they can be accurately found.

Thank you very much for your comments and suggestions! Special thanks to you for your good comments. We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. And here we did not list the changes but marked in red in revised paper.

Once again, thank you very much for your comments and suggestions.

 

 

Reviewer 3 Report

Comments and Suggestions for Authors

1. For Sustainability (MDPI) or similar journals, the abstract should emphasize broader sustainability implications, including how does this method compare to conventional waste disposal or other filling techniques, the cost saving or economic specialties, is their social impact of these study also the contribution to circular economy principles or long -term sustainability.
2. The title to be aligned with a sustainability journal’s scope, it should contain words like, Sustainable Utilization" or "Eco-friendly Mining Practices." ..e.g.
3. Cited reference style was not MDPI
4. Sources of Fig. 1, should be provided
5. Paper novelty and hypothesis should be provided clearly
6. Section “engineering background” was not understood, it is vague
7. The material manufacturer should be provided for material used
8. What “ , the #1 and #2” change to number
9. Experimental procedures were not clear
10. “Field test results and discuss” change to result and discussion
11. How compression strength was measured in Table 6
12. More analysis and discussion needed
13. The study focuses primarily on water pollution, but lacks a comprehensive assessment of long-term environmental impacts, such as soil pollution, air emissions and ecological consequences of phosphogypsum use.
14. The study is based on small-scale experiments in a single mine, which limits its applicability to other mining sites with different geological and hydrological conditions. A broader study across multiple sites is required.

Comments on the Quality of English Language

accepted

Author Response

Dear Reviewer：

Thank you for your letter and for the reviewers' comments concerning our manuscript entitled “Field test of phosphogypsum filling based on slag powder”(ID:sustainability-3540176). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. The main corrections in the paper and the responds to your comments are as flowing：

 

Response to comment:1.For Sustainability (MDPI) or similar journals, the abstract should emphasize broader sustainability implications, including how does this method compare to conventional waste disposal or other filling techniques, the cost saving or economic specialties, is their social impact of these study also the contribution to circular economy principles or long -term sustainability.

Thanks for your guidance, some modifications have been completed in the article, particularly in the title and abstract.

Response to comment:2.The title to be aligned with a sustainability journal’s scope, it should contain words like, Sustainable Utilization" or "Eco-friendly Mining Practices." ..e.g.

The new title is" Eco-friendly Mining Practices：Field test of phosphogypsum filling based on slag powder in Dayukou phosphate mine."

Response to comment:3.Cited reference style was not MDPI

Thank you for your guidance, and we have completed the modification as required.

Response to comment:4.Sources of Fig. 1, should be provided.

Sources are added in the paper.L46-48.

Response to comment:5.Paper novelty and hypothesis should be provided clearly.

This paper validated the feasibility of the phosphogypsum backfilling technique based on slag micro-powder and this part is referred to in the introduction and conclusion.

Response to comment:6.Section “engineering background” was not understood, it is vague

We have rewritten this part according to your suggestion.

Response to comment:7.The material manufacturer should be provided for material used

Relevant instructions have been added in the L109, 110, 111,203.

Response to comment:8.What “ , the #1 and #2” change to number

We are very sorry for our incorrect writing,these modifications are added in the paper.

Response to comment:9.Experimental procedures were not clear.

We have modified the formulation.

Response to comment:10.“Field test results and discuss” change to result and discussion

Thanks for your suggestions, the modified discussion section is listed separately as part 4.

Response to comment:11.How compression strength was measured in Table 6

The test methods and description were added in the paper,L199-203.

Response to comment:12.More analysis and discussion needed

We have rewritten this part according to your suggestion.

Response to comment:13.The study focuses primarily on water pollution, but lacks a comprehensive assessment of long-term environmental impacts, such as soil pollution, air emissions and ecological consequences of phosphogypsum use.

It is really true as you suggested,we will monitor the mine for a long time,continue to study these effects.

Response to comment:14.The study is based on small-scale experiments in a single mine, which limits its applicability to other mining sites with different geological and hydrological conditions. A broader study across multiple sites is required.

Thank you for your advice. We will continue to this study in other mines in the future.

Finally, thanks again for your guidance!Special thanks to you for your good comments. We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. And here we did not list the changes but marked in red in revised paper.

Once again, thank you very much for your comments and suggestions.

 

 

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

it is ok, the author responds all comment 

Comments on the Quality of English Language

N/A