Extraction of Lead and Zinc from a Rotary Kiln Oxidizing Roasting Cinder
Victor Acha
Round 1
Reviewer 1 Report
There is no innovative elements found in this work as the methods of extraction and characterization used in this study are well known and already published. The authors have to be able to explain in a clear way why this present work is original. This is usually done by reviewing and discussing already published works to bring out the innovative aspects. By the way, there is no discussion of results obtained in this study with other reported works.
In addition, this manuscript suffers from writing uncertainties such as typos. Some details are indicated below:
Abstract: What is the context of this study?
Abstract: What is the objective of this study? What are the perspectives?
Abstract: What is the fate of Fe and S obtained from Pb-Zn sulfide?
The Abstract has to be improved representing clearly the work done.
Writing problem: the authors sometimes write in the present tense but sometimes in the past tense too.
Introduction: What makes this study innovative? New approaches?
Experimental section: Need to provide more details about all apparatus and procedures used for characterization of samples. A paper has to be full of information for readers to better understand.
Conclusion; This section has to show the objective of this study, the methods used, the main results and finally the spinoff on the work done.
Conclusion: Define “sulfurating rosating ».
Author Response
Response to Reviewer 1 comments
Point 1：Abstract: What is the context of this study?
Response 1：There are a large amount of copper lead zinc polymetallic sulfide ores in Hanyuan area of China. Due to the complex ore composition, qualified copper concentrate (Cu > 20%) and partially qualified lead concentrate (Pb > 60%, Pb + Zn > 30%) can be obtained by flotation. Qualified copper concentrate and lead concentrate products can be sold directly as products. But mixed lead - zinc concentrate need further processing, the local mining enterprises with oxidizing roasting - separate the mixed lead - zinc concentrate water leaching process of lead, zinc, due to the oxidation roasting process, the atmosphere control accuracy is poorer, sulfide ore and oxygen reaction is a mixture of oxide and sulphate, lead and zinc in the process of water separation effect is poorer. Relevant background information has been added, please review it.
Point 2：Abstract: What is the objective of this study? What are the perspectives?
Response 2：Here we express improper, the object of this paper is the mixed lead - zinc concentrate after oxidative roasting produced by the roasting slag.
Point 3：Abstract: What is the fate of Fe and S obtained from Pb-Zn sulfide?
Response 3： Here is the mixed lead-zinc concentrate produced in the form of sulfur dioxide in the form of sulfur dioxide after contact with oxygen in the oxidizing roasting process, and some sulfate in the oxidizing roasting slag. Pyrite contacts with oxygen to form hematite or magnetite in the process of oxidizing roasting, while some hematite and zinc oxide form part of zinc ferrite.
Point 4：The Abstract has to be improved representing clearly the work done.
Response 4：Thank you for your review. We have revised the summary part. Please review it.
Point 5：Writing problem: the authors sometimes write in the present tense but sometimes in the past tense too.
Response 5：Thank you for your suggestion. We have made a lot of changes to the language expression for this serious mistake in our writing. Please review it.
Point 6：Introduction: What makes this study innovative? New approaches?
Response 6： In this paper, the specific separation of lead and zinc technology is studied according to the local actual production situation, and the technical plan is provided for the subsequent industrial production. Lead concentrate and zinc-rich leachate can be obtained by the acid leaching-heavy separation process proposed in this paper. The main ions of the leachate are Zn2+ and SO42-.ZnSO4 •7H2O should be added as an inhibitor because the local concentrator is important in the flotation separation process of copper lead zinc sulfide ore. Therefore, the leachate produced in the acid leaching process can be used as an important raw material for the preparation of ZnSO4 •7H2O and as an inhibitor of the flotation separation process of copper lead zinc sulfide ore.
Point 7：Experimental section: Need to provide more details about all apparatus and procedures used for characterization of samples. A paper has to be full of information for readers to better understand.
Response 7：Thank you for your suggestion. We do have the problem of incomplete expression here. We have made corresponding improvements according to your suggestion.
Point 8：Conclusion; This section has to show the objective of this study, the methods used, the main results and finally the spinoff on the work done.
Response 8：Thank you for your suggestion. Here is that our summary is not accurate enough. We will revise it.
Point 9：Conclusion: Define “sulfurating rosating ».
Response 9：This is an improper expression. We have modified it. Thank you.
Finally, thank you again for your review. The main innovation of this paper lies in the separation of lead and zinc from oxidized calcined slag by sulfuric acid leaching and shaking bed gravity separation. The research on theoretical analysis is not deep enough, but our research has a strong operability for the practical industrial application, using relatively simple and practical technical route to achieve the effective separation of lead and zinc. Therefore, this paper has important practical application value, at the same time we also carried out a lot of modification work, hope to get your approval. Of course, there may still be a lot of problems, and we would appreciate your Suggestions for further revision.
Kind regards,
Junhui Xiao
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Acceptable for publication.
Author Response
Response to Reviewer 2 comments
Dear reviewer,
Thank you very much for your review and recognition of our research work. Your precious comments will pay a great help in improving our article. Finally, thank you again for your review work, which is very meticulous and will greatly improve the level of our article. At the same time, we also hope that you can put forward precious suggestions again, which will be conducive to the improvement of our follow-up work. If you have any questions, please feel free to contact us.
Kind regards,
Junhui Xiao
Author Response File: Author Response.pdf
Reviewer 3 Report
The approach taken by the authors to separate lead and zinc from a mixed Pb-Zn concentrate is sensible and appears to give good outcomes in terms of leaching a large proportion of the zinc and in forming a high-lead containing concentrate. There are aspects of the work that seem to be not well understood. Certainly, has not been made clear to this reviewer what is chemically and mineralogically occurring when the “oxidizing roasting ore” is processed.
Major issues with this paper are as follows:
- The interpretation of the XRD data is questionable for some phases while there is no reference back to the relevant database patterns used to assign the mineral phases. For the leach residue and lead concentrate solids the interpretation of a lead sulfate phase being present is not justified by the evidence provided. The peaks are certainly not those of anglesite (PbSO4) but if I had to guess, these might be indicative of a phase such as beaverite. The authors talk about the formation of a zinc sulfate mineral but provide no evidence for this. It is possible that the zinc is incorporated into a phase such as beaverite but if so, the evidence needs to be provided. Could SEM/EDS analysis be used to indicate the composition of the lead-containing phase?
- The authors talk about using mineral names but for the most part tend to use chemical formulas;
- Critical information is missing from the experimental section while some of the information provided is unclear. For example, it is indicated that sulfinic acid is used to enhance zinc leaching from zinc ferrite. As sulfinic acid refers to a group of organic acids so it is expected that the authors actually used sulfurous acid;
- In relation to the use of sulfurous acid, the authors indicate (without reference to previous data/publications) that this will only act on zinc ferrite and not affect the leaching of other ferrites suggested to be present in the ore;
- No information provided on the behaviour of major metals Pb, Fe during leaching;
- The experiments do not logically derive optimum conditions. I don’t have a problem with this, but it needs to be stated for the reader that, for example, optimum solid:liquid ratio was employed when investigating other parameters such as the sulfuric acid dosage;
- There are several sections that describe fundamental aspects of the science that do not add value to the article as such aspects will be well understood by those with expertise in the hydrometallurgical processing field;
- Upon closer inspection, the elemental data in Table 9 are the same as those in Table 7 except for Pb. When converted to their corresponding oxides the values in Table 9 sum to around 116% confirming the values must be incorrect;
- SEM/EDS data is presented but the interpretation of these data is not clearly described.
There are a multitude of other issues that include English expression that requires improvement and further comments/queries that need to be addressed. A copy of the manuscript with suggested changes to the wording and other comments is provided for the authors to consider.
Comments for author File: Comments.pdf
Author Response
Response to Reviewer 2 comments
Point 1：The interpretation of the XRD data is questionable for some phases while there is no reference back to the relevant database patterns used to assign the mineral phases. For the leach residue and lead concentrate solids the interpretation of a lead sulfate phase being present is not justified by the evidence provided. The peaks are certainly not those of anglesite (PbSO4) but if I had to guess, these might be indicative of a phase such as beaverite. The authors talk about the formation of a zinc sulfate mineral but provide no evidence for this. It is possible that the zinc is incorporated into a phase such as beaverite but if so, the evidence needs to be provided. Could SEM/EDS analysis be used to indicate the composition of the lead-containing phase?
Response 1: Thank you very much for your review. The phase in the oxidized roasting slag was analyzed by chemical phase analysis method to analyze the composition of sulfate and oxide, and the major mineral phases in the oxidized roasting slag were qualitatively analyzed by XRD. SEM/EDS can be used for the analysis of micro-components and the qualitative properties of reactive materials.
Point 2：The authors talk about using mineral names but for the most part tend to use chemical formulas;
Response 2: We have modified the unreasonable expression here. Thank you very much for your suggestion.
Point 3：Critical information is missing from the experimental section while some of the information provided is unclear. For example, it is indicated that sulfinic acid is used to enhance zinc leaching from zinc ferrite. As sulfinic acid refers to a group of organic acids so it is expected that the authors actually used sulfurous acid;
Response 3: In the experiment, we used sulfurous acid as the collaborative leaching agent in the sulfuric acid leaching process. Through the experiment, we found that adding sulfurous acid could indeed improve the leaching rate of zinc.
Point 4：In relation to the use of sulfurous acid, the authors indicate (without reference to previous data/publications) that this will only act on zinc ferrite and not affect the leaching of other ferrites suggested to be present in the ore;
Response 4: Thank you for your review. You proposed that under the premise of increasing the temperature, zinc ferrite could react with sulfuric acid to form iron sulfate and zinc sulfate. However, we found that the leaching effect of only adding zinc sulfate was not ideal in the actual material leaching test. We drew the conclusion according to the material composition and the basic knowledge of chemical reaction. Of course, we also need to supplement the relevant thermodynamic data later, which can effectively provide the corresponding evidence.
Point 5：No information provided on the behaviour of major metals Pb, Fe during leaching;
Response 5: In the mixed lead-zinc concentrate produced by flotation of the local copper-lead-zinc polymetallic sulfide ore, the main mineral is the solid solution of galena and sphalerite, followed by a small amount of marmatite and pyrite. Therefore, the changes of lead and zinc are mainly investigated in the test process. Through the test, the author hopes to solve the separation of lead and zinc from the oxidized calcined slag technically in combination with the local production situation, so as to provide support for the subsequent process production。
Point 6：The experiments do not logically derive optimum conditions. I don’t have a problem with this, but it needs to be stated for the reader that, for example, optimum solid:liquid ratio was employed when investigating other parameters such as the sulfuric acid dosage;
Response 6: Thank you for your recognition of our experimental work. We double-checked the original record and found that the solid –liquid ratio should actually be 1∶4.
Point 7：There are several sections that describe fundamental aspects of the science that do not add value to the article as such aspects will be well understood by those with expertise in the hydrometallurgical processing field;
Response 7: Thank you for your review. This paper is indeed weak in theory. The focus is on how to obtain a simple, feasible and applicable technical route through experiments according to the problems in the production process of local concentrator, which is also the focus of this study.
Point 8：Upon closer inspection, the elemental data in Table 9 are the same as those in Table 7 except for Pb. When converted to their corresponding oxides the values in Table 9 sum to around 116% confirming the values must be incorrect;
Response 8: Here is the serious mistake we made in the process of writing the paper. I checked the original record data and made modifications. Please review it. Thank you for your careful review.
Point 9：SEM/EDS data is presented but the interpretation of these data is not clearly described. There are a multitude of other issues that include English expression that requires improvement and further comments/queries that need to be addressed. A copy of the manuscript with suggested changes to the wording and other comments is provided for the authors to consider.
Response 9: Thank you very much for your Suggestions, especially for the substantial amendments to the extensive expressions in the text, for which we are very grateful. In addition, we also modify the inappropriate expressions in other parts of the article.
At the same time, I want to tell you something. In this paper, the specific separation of lead and zinc technology is studied according to the local actual production situation, and the technical plan is provided for the subsequent industrial production. Lead concentrate and zinc-rich leachate can be obtained by the acid leaching-heavy separation process proposed in this paper. The main ions of the leachate are Zn2+ and SO42-.ZnSO4 •7H2O should be added as an inhibitor because the local concentrator is important in the flotation separation process of copper lead zinc sulfide ore. Therefore, the leachate produced in the acid leaching process can be used as an important raw material for the preparation of ZnSO4 •7H2O and as an inhibitor of the flotation separation process of copper lead zinc sulfide ore.
The main innovation of this paper lies in the separation of lead and zinc from oxidized calcined slag by sulfuric acid leaching and shaking bed gravity separation. The research on theoretical analysis is not deep enough, but our research has a strong operability for the practical industrial application, using relatively simple and practical technical route to achieve the effective separation of lead and zinc. Therefore, this paper has important practical application value, at the same time we also carried out a lot of modification work, hope to get your approval. Of course, there may still be a lot of problems, whether the final paper is accepted or not, we also hope that you can make further Suggestions for modification, we will be very grateful.
Kind regards,
Junhui Xiao
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have provided some answers and modifications to most of the aspects pointed out in the previous review. However some of the important remarks have not been answered by the authors:
Why this study is original? There is no innovative elements in this work. The authors are limited to say at the end of the introduction section: “…Therefore, the separation tests of lead and zinc from the oxidizing roasting slag produced from the mixed Pb-Zn sulfide concentrate were carried out…”. Why? What other studies performed similar works? What are the advantages of this study over these other studies?
The Abstract does not show a context nor the objectives of this study. Readers read first the Abstract, if the Abstract is not written in a clear way, ther are not going to read the paper.
The Conclusion section is just a summary of the results obtained. This section has to show in addition to the main results the objectives of the work done, and also some perspectives. Reading just the conclusion section readers have to be able to understand everything about the work done in this study.
Author Response
Response to Reviewer 1 comments
Point 1: Why this study is original? There is no innovative elements in this work. The authors are limited to say at the end of the introduction section: “…Therefore, the separation tests of lead and zinc from the oxidizing roasting slag produced from the mixed Pb-Zn sulfide concentrate were carried out…”. Why? What other studies performed similar works? What are the advantages of this study over these other studies?
Response 1: Thank you again for your review. We are very sorry for the misunderstanding caused by our improper expression. The innovation of this paper lies in the use of practical technical means to realize the separation of valuable technology of lead and zinc, aiming at the oxidized roasting cinder of a rotary kiln. The oxidation of sulfide ore roasting or sulphation roasting all belong to the conventional techniques, but using rotary kiln roasting sulfide ore, due to the roasting temperature and roasting atmosphere is more difficult to achieve precise control, therefore the hybrid lead - zinc sulphide ore concentrate produced in the process of rotary kiln oxidizing roasting cinder is a mixture of oxide and sulphate. In this study, the separation of lead and zinc was realized by acid leaching and heavy separation of shaking bed, which provided a feasible technical scheme for subsequent industrial production and was of practical significance for practical application.
Point 2: The Abstract does not show a context nor the objectives of this study. Readers read first the Abstract, if the Abstract is not written in a clear way, ther are not going to read the paper.
Response 2: Thank you for your Suggestions. We have revised with your and other reviewers' comments, please review.
Point 3: The Conclusion section is just a summary of the results obtained. This section has to show in addition to the main results the objectives of the work done, and also some perspectives. Reading just the conclusion section readers have to be able to understand everything about the work done in this study.
Response 3: Thank you for your review. According to your Suggestions, the conclusion of the paper is also modified according to the research results. Please review it.
Finally, thank you again for your review. We have made a lot of additions and improvements to the article again, and we hope that our hard work can be recognized by you again. Of course, the basic theory of this paper is relatively weak, but from the combination of basic theoretical knowledge to solve practical problems is of great value. At the same time, this paper may still have many shortcomings, and we sincerely hope that you again put forward valuable suggestions, will have a large role in promoting our work.
Kind regards,
Junhui Xiao
Author Response File: Author Response.pdf
Reviewer 3 Report
While this paper is significantly improved, and the outcomes from the work would be of interest to other readers, it remains scientifically flawed. In parts it is quite verbose without conveying much in the way of science. I have attempted to fix much of this up in the attachment provided, but I must now ask the authors to put together some consistent, well interpreted characterisation data to describe the solid materials used and produced in their study. This will enable them to generate a paper that describes how their process works.
The major concerns with this article are as follows:
- The authors still do not describe how the roasted material was produced and are not consistent in naming it. It appears to be incompletely roasted and hence sulfates remain in the product. Also, it is not a slag material as it contains the metal values. I have used the term “cinder” to describe the product of oxidizing roasting;
- The XRD data remain incompletely and inconsistently interpreted. Certainly, it seems that a new lead-containing phase is formed during leaching, probably from the lead oxide component of the cinder. There is also reference to zinc phases in the leach residue, but these will be incompletely leached ones not newly formed as the authors seem to suggest. The EDS data are shown but also appear to be inconsistently labelled. The authors do not address what information these data provide;
Unfortunately, I cannot allow the paper to be accepted based upon just its technical merit in demonstrating the effective separation of zinc from lead. I would encourage you to properly address my concerns before resubmitting this paper for publication.
Comments for author File: Comments.pdf
Author Response
Response to Reviewer 3 comments
Point 1: The authors still do not describe how the roasted material was produced and are not consistent in naming it. It appears to be incompletely roasted and hence sulfates remain in the product. Also, it is not a slag material as it contains the metal values. I have used the term “cinder” to describe the product of oxidizing roasting;
Response 1: Thank you again for your thoughtful suggestions. Our negligence has caused you trouble in your review work. At the same time, we also revised the title of the article, and added literature review and references, please review.
Point 2: The XRD data remain incompletely and inconsistently interpreted. Certainly, it seems that a new lead-containing phase is formed during leaching, probably from the lead oxide component of the cinder. There is also reference to zinc phases in the leach residue, but these will be incompletely leached ones not newly formed as the authors seem to suggest. The EDS data are shown but also appear to be inconsistently labelled. The authors do not address what information these data provide;
Response 2: Thank you for your careful review. The analysis here is the result of comparing the chemical reaction in the process of oxidizing roasting with the standard database of minerals. Because of the complex composition of oxidizing roasting slag, XRD and EDS analysis can be used as qualitative analysis, but it is difficult to make quantitative analysis. The analysis results can be used to discuss and verify the experimental results.
Point 3: Unfortunately, I cannot allow the paper to be accepted based upon just its technical merit in demonstrating the effective separation of zinc from lead. I would encourage you to properly address my concerns before resubmitting this paper for publication.
Response 3: Thanks for your advice. In view of your comments on modification marked in PDF, we have consulted relevant literature and improved the missing parts in the article, please review.
Finally, I sincerely thank you for putting forward such valuable suggestions for revision of our research. After two reviews, we have gained a lot, especially providing important guidance for our follow-up research work. In fact, the final result may not be the most crucial, but your rigorous attitude and spirit towards scientific research will give us a clearer direction. There may still be insufficient support for this article. Please give us your valuable Suggestions again. We are still very grateful. If you have any questions, please feel free to contact us.
Yours sincerely,
Junhui Xiao
Author Response File: Author Response.pdf
Round 3
Reviewer 1 Report
The authors have provided answers and modifications to almost of the aspects pointed out in the previous review. I have no more comments.
Good luck
Author Response
Response to Reviewer 1 comments
Dear reviewer,
Thank you for your recognition of our previous two revisions. We have modified part of the article again. Thank you for your review work. Maybe our revision work cannot be perfect, but we will strengthen this aspect of research in the follow-up work and try our best to make the research work rigorous. Finally, I hope to have another opportunity to present our other research results to you for review, and I hope you will take the trouble to give us suggestions. Wish you all the best in 2020!
Kind regards,
Junhui Xiao
Author Response File: Author Response.pdf
Reviewer 3 Report
Thank you for addressing some of my concerns. The main issue remaining is the materials characterization section. Please have a close look at my comments in the attachment in which I believe I may have identified the lead sulfate-rich phase. I would ask you to double check this and make sure that the oxygen content is consistent with your analytical data. If not I would suggest you simply talk about the peaks as being those of a lead sulfate-rich phase of uncertain composition. I asked previously but will now insist you fix up the EDS spectral axes and assignments so these are consistent and correct. I have spent a great deal of time on this manuscript to ensure that is as scientifically accurate as possible.
A number of minor wording changes are suggested in the attachment. Please consider these carefully and comprehensively.
Comments for author File: Comments.pdf
Author Response
Response to Reviewer 3 comments
Dear reviewer,
Thank you for your approval of our last two revisions. According to your suggestions on modifying the PDF article, we have modified part of the article again. Thank you for spending so much time reviewing our article. Words can hardly describe how grateful we are to you. Maybe our revision can't be perfect, but we will strengthen this aspect of research in the follow-up work and try our best to make the research work rigorous. Finally, I hope to have another opportunity to present our other research results to you for review, and I hope you will take the trouble to make suggestions. We are still very grateful. If you have any questions, please feel free to contact us. Wish you all the best in 2020!
Yours sincerely,
Junhui Xiao
Author Response File: Author Response.pdf
