Distribution, Separation and Characterisation of Valuable Heavy Minerals from the Brahmaputra River Basin, Kurigram District, Bangladesh

Round 1

Reviewer 1 Report

In the present manuscript, the authors have discussed about the distribution, separation, and characterization of valuable heavy minerals from the Brahmaputra River Basin, Kurigram District of Bangladesh region. The manuscript is within the scope of this journal and well written as well. I suggest to add the definition of "valuable heavy minerals" and in brief their variance to other minerals. This can be included in the starting of the introduction to smoothly enter the subject of the manuscript. Hence, the manuscript can be accepted after a minor revision.

 

Author Response

We thank Reviewer#1 for their comments on our manuscript. The valuable heavy minerals are defined in the introduction (lines 39-41) as comprising zircon, rutile, ilmenite, garnet, kyanite, leucoxene, magnetite and monazite. References 4 and 5 provide additional details as to why they are valuable.

Reviewer 2 Report

The paper “Distribution, separation, and characterization of valuable heavy minerals from the Brahmaputra River Basin, Kurigram District, Bangladesh”, by Rahman et al., investigate heavy minerals from Bangladesh, Brahmaputra River Basin.

The paper presents enough quality to be published in “Waste Management”. The paper is interesting but, in my opinion, too long. The data should be summarized or excluded.

Please, try to represent tables 1, 3, and 6 as figures, or exclude them.

Please, if possible, remove figures 7, 8, and 9. They are not necessary.

In general, the paper is interesting and well presented.

 

Author Response

We thank the reviewer for their comments. The data in Table 1 is captured in Figs, 3a and 3b although the actual positions are not given in the figure. It would make Figure 3 very busy if the data were added to specific sites and we have therefore elected to retain Table 1 in its present form so the reader can see the variability in real terms.

We have accepted the advice of the reviewer and removed Table 3 as the results are discussed in the text.

Table 6 (now Table 5 in revised version) has been modified to exclude oxides not directly referred to in the text.

We believe that Figures 7, 8 and 9 form an integral part of the paper and have chosen not to remove them. They visually demonstrate the distribution of the VHMs in the separated concentrates and by extension the quality of the product.

Reviewer 3 Report

Authors have tried to characterize a riverbed heavy mineral deposit from Bangladesh. It is focused more on characterization with minimum beneficiation studies. However, the article is not prepared well to publish in a journal. It looks like a technical test report. However, there are a few points mentioned below that need to be addressed before publication:

• The whole paper looks like a chapter in the project feasibility report. So, effort should be made for a better analysis of the problem statement.

• author needs to mention the demand for this research in the introduction, abstract and concussion.

• The abstract needs to be revised by incorporating an innovative step adopted in the current research.

• Author should avoid abbreviations in the title, abstract and conclusion.

• The whole research paper is prepared with few characterisation data and a lack of enough beneficiation study results. There should be more discussion on each section by using depiction tools/figures/tables which are missing.

• In the research paper, the author must list down the existing technology to address the present problem in the flotation of iron ore. The author should describe the influence of parameters, adsorption mechanism, thermodynamics, merit and demerit, as well as industrial application of such process.

• On what basis authors have chosen the beneficiation units? The author should narrate the hypothesis and mention it.

• The discussion part is very week in this research paper as most of the places. The author only explained the observation of the experimental results. The author should improve on this by adding content on different characterisation tools.

• There are several parameters that influence the beneficiation separation processes used. The basis of the selection of variables on each process needs to be justify and discuss along with proper citations.

• There are several figures and tables which may not require. Please revisit and delete the irrelevant ones. For example, Figure 2: This information can be included in the text rather than separate figure as Figure 5 also the same.

• The details of the experiment and characterisation set up and the error involved in measurement must include in the paper.

• Conclusion: Better rewrite the section with crisp result values achieved through analysis and comparison in a single paragraph.

• The English language needs to be given attention and request authors to refine sentences with the right choice of words. The manuscript needs a thorough revision of its language and style. Overall, this paper is very difficult to read. Avoid redundancies and keep it short. I suggest a comprehensive overhaul of the text for a more precise understanding of the reader.

• The authors have presented the possibility of multiple streams of valuable heavy minerals. There are issues with the breakdown/split between these streams in terms of value as well as recovery.
• Also, the author should compare the findings with  typical heavy mineral sands deposits.
• Generally, such deposits are potential for REE. Did the authors consider the potential of concentrating any of the rare earth minerals present in the deposit such as monazite/xenotime or others?
• Should the XRF results be presented as raw elemental information rather than as expected oxide content? I realize this is against typical geological conventions however presenting elements such as Zr content as ZrO2 is likely to confuse readers when discussing the actual minerals in which the elements are found (i.e. zircon, ZrSiO4).

 

• In most cases,  beneficiation results are preliminary in nature which is not considered for the flowsheet development. So, please mention the optimization strategy for obtaining the best grade/recovery results.
• Finally, the conclusions in this work are far too long and should be much more concise in summarizing the important points for the reader to take from the work rather than restating all findings.
  
  • References: There are many articles on this subject. The author needs to review all of these published articles on iron ore flotation with emphasis on the present research subject. Please revisit the cited references carefully and request to include the published literature on this subject. A few of these have listed below for reference:
  
   Ityokumbul, M. T., et al. "Froth flotation for the beneficiation of heavy minerals from oil sand tailings." AOSTRA Journal of Research 2.1 (1985): 59-66.
   Kaminsky, Heather AW, et al. "Characterization of heavy minerals in the Athabasca oil sands." Minerals Engineering 21.4 (2008): 264-271.
   Rejith, Rajan Girija, and Mayappan Sundararajan. "Combined magnetic, electrostatic, and gravity separation techniques for recovering strategic heavy minerals from beach sands." Marine Georesources & Geotechnology 36.8 (2018): 959-965.
   Chen, Luzheng, et al. "A novel process for titanium sand by magnetic separation and gravity concentration." Mineral Processing and Extractive Metallurgy Review 34.3 (2013): 139-150.
   Babu, N., N. Vasumathi, and R. Bhima Rao. "Recovery of ilmenite and other heavy minerals from teri sands (red sands) of Tamil Nadu, India." Journal of Minerals and Materials Characterization and Engineering 8.2 (2009): 149-159.
   Hossain, Md Sakaouth, Md Tawhidul Aziz, and Md Shams Shahriar. "Heavy Mineral Analysis of Jamuna River Sediments, Bangladesh." Journal of the Geological Society of India 97.5 (2021): 470-480.
   Singh, Veerendra, and S. Mohan Rao. "Selective classification of mineral sand slimes in an air fluidized bed." Mineral Processing & Extractive Metallurgy Review 31.2 (2010): 59-72.

Author Response

Reviewer #3

Authors have tried to characterize a riverbed heavy mineral deposit from Bangladesh. It is focused more on characterization with minimum beneficiation studies. However, the article is not prepared well to publish in a journal. It looks like a technical test report. However, there are a few points mentioned below that need to be addressed before publication:

We thank the reviewer for their comments however we wish to point out that we clearly state in the introduction (lines 77-83) that beneficiation of the river sands is only a tool used in order to provide suitable material for in-depth characterisation studies.

• The whole paper looks like a chapter in the project feasibility report. So, effort should be made for a better analysis of the problem statement.

We agree with the reviewer that the paper is a high-level feasibility study designed to examine whether it may be possible to generate valuable heavy mineral concentrates from the Brahmaputra River sands. It is necessary to demonstrate the feasibility before progressing to more detailed beneficiation studies. We believe we have successfully shown that it is possible to recover valuable heavy minerals but further work is required to optimise the separation of the components. The problem we are addressing is clearly stated in lines 77-83. Our conclusions clearly support our objections (lines 527-530) “This study has demonstrated that it is possible to recover VHM components from the Brahmaputra River sands but more in-depth studies with samples from different regions in the basin are necessary to identify prospective areas and further work is necessary to develop more efficient beneficiation processes for the VHMs.”

• author needs to mention the demand for this research in the introduction, abstract and concussion.

As indicated in the point above, we have clearly articulated why we did the research and what are the potential outcomes. Nonetheless we have added a section in the introduction justifying our research.

• The abstract needs to be revised by incorporating an innovative step adopted in the current research.

The innovative work is to demonstrate the potential of producing valuable heavy mineral concentrates from low grade river sands – see new section added as noted above.

• Author should avoid abbreviations in the title, abstract and conclusion.

According to recent scientific paper style guidelines “Avoid acronyms in the abstract unless the acronym is commonly understood and used multiple times in the abstract. If an acronym is used in the abstract, it must be spelled out (defined) in the abstract”. Because we use the terms VHM and THM a number of times in the abstract and conclusions we fill it is better to use the acronym where possible to avoid making these sections longer in length.

• The whole research paper is prepared with few characterisation data and a lack of enough beneficiation study results. There should be more discussion on each section by using depiction tools/figures/tables which are missing.

We find this comment by the reviewer confusing. We have provided extensive examples of characterisation data (Table 5 and Figures 6-11). Yes, there is a lack of beneficiation results as this was not the focus of the paper as indicated in the introduction. Beneficiation was only used to generate sufficient material to characterise the products.

• In the research paper, the author must list down the existing technology to address the present problem in the flotation of iron ore. The author should describe the influence of parameters, adsorption mechanism, thermodynamics, merit and demerit, as well as industrial application of such process.

Again, this is a very confusing comment. This is not a paper on iron ore so the comment about flotation of iron ore is irrelevant.

• On what basis authors have chosen the beneficiation units? The author should narrate the hypothesis and mention it.

Thank you to the reviewer for allowing us to clarify this point. We now state in Section 3.2 that gravity, magnetic and electrostatic separations as practised in industry were used to produce the concentrates for characterisation. As this is not a beneficiation paper we do not think it is necessary to provide a detailed justification of why we used these techniques – the separation of VHMs from mineral sands is standard industry practice.

• The discussion part is very week in this research paper as most of the places. The author only explained the observation of the experimental results. The author should improve on this by adding content on different characterisation tools.

We are confused by this statement. We provide extensive description (section 2.3) discussion and comment (section 3.3) of each of the characterisation techniques used in our study. We are uncertain as to what possible improvements we could make.

• There are several parameters that influence the beneficiation separation processes used. The basis of the selection of variables on each process needs to be justify and discuss along with proper citations.

We agree with the reviewer that there are beneficiation parameters that could be explored further – and we are indeed doing this. However, as stated above, this is a primarily a characterisation paper – the beneficiation aspect was simply provided to show how the VHMs cane be concentrated for further characterisation testwork. A more focussed beneficiation study is currently the subject of our future work as recommended in the conclusions.

• There are several figures and tables which may not require. Please revisit and delete the irrelevant ones. For example, Figure 2: This information can be included in the text rather than separate figure as Figure 5 also the same.

Thank-you for this comment. We have removed Table 3 as the data is discussed in the text. We think it is better to leave Figure 2 in the text to illustrate the separation route (which is not discussed in detail in the text).

• The details of the experiment and characterisation set up and the error involved in measurement must include in the paper.

As indicated above, we provide extensive description (section 2.3) of the characterisation techniques used in our study.

• Conclusion: Better rewrite the section with crisp result values achieved through analysis and comparison in a single paragraph.

The conclusion has been reduced in size as requested.

• The English language needs to be given attention and request authors to refine sentences with the right choice of words. The manuscript needs a thorough revision of its language and style. Overall, this paper is very difficult to read. Avoid redundancies and keep it short. I suggest a comprehensive overhaul of the text for a more precise understanding of the reader.

Although the first author of this paper is a non-native English speaker, the paper has been extensively reviewed and edited by at least four other native English-speaking authors who are all experienced scientific paper writers. We find this comment confusing.

• The authors have presented the possibility of multiple streams of valuable heavy minerals. There are issues with the breakdown/split between these streams in terms of value as well as recovery.

That is true, there are problems (e.g. for the ilmenite stream) however we clearly state this in the text and point out that additional work is needed. Optimising the beneficiation for each of the VHM products was not the objective of this work.

• Also, the author should compare the findings with  typical heavy mineral sands deposits.

Please see the Introduction section where we discuss how the grade of heavy minerals derived from river sand deposits differs significantly from normal beach sand deposits.

• Generally, such deposits are potential for REE. Did the authors consider the potential of concentrating any of the rare earth minerals present in the deposit such as monazite/xenotime or others?

As indicated by our characterisation results (and in previous work noted in the Introduction), the amount of monazite in the river sands deposits was very low (even in the zircon fraction where it would be expected to report). We therefore did not consider recovering monazite.

• Should the XRF results be presented as raw elemental information rather than as expected oxide content? I realize this is against typical geological conventions however presenting elements such as Zr content as ZrO2 is likely to confuse readers when discussing the actual minerals in which the elements are found (i.e. zircon, ZrSiO4).

We do not believe this is an issue as it is against typical convention (as pointed out by the reviewer)

• In most cases,  beneficiation results are preliminary in nature which is not considered for the flowsheet development. So, please mention the optimization strategy for obtaining the best grade/recovery results.

Yes, the beneficiation results are preliminary in nature and we clearly indicate that beneficiation was only used to generate material for characterisation. In the discussion section for each of the VHM products we include suggestions as to how the beneficiation could be improved but this is the subject of further work i.e. a beneficiation-focussed paper.

• Finally, the conclusions in this work are far too long and should be much more concise in summarizing the important points for the reader to take from the work rather than restating all findings.

We have condensed the Conclusions as much as we feel possible without losing any important conclusions.

• References: There are many articles on this subject. The author needs to review all of these published articles on iron ore flotation with emphasis on the present research subject. Please revisit the cited references carefully and request to include the published literature on this subject. A few of these have listed below for reference:

ü Ityokumbul, M. T., et al. "Froth flotation for the beneficiation of heavy minerals from oil sand tailings." AOSTRA Journal of Research 2.1 (1985): 59-66.
ü Kaminsky, Heather AW, et al. "Characterization of heavy minerals in the Athabasca oil sands." Minerals Engineering 21.4 (2008): 264-271.
ü Rejith, Rajan Girija, and Mayappan Sundararajan. "Combined magnetic, electrostatic, and gravity separation techniques for recovering strategic heavy minerals from beach sands." Marine Georesources & Geotechnology 36.8 (2018): 959-965.
ü Chen, Luzheng, et al. "A novel process for titanium sand by magnetic separation and gravity concentration." Mineral Processing and Extractive Metallurgy Review 34.3 (2013): 139-150.
ü Babu, N., N. Vasumathi, and R. Bhima Rao. "Recovery of ilmenite and other heavy minerals from teri sands (red sands) of Tamil Nadu, India." Journal of Minerals and Materials Characterization and Engineering 8.2 (2009): 149-159.
ü Hossain, Md Sakaouth, Md Tawhidul Aziz, and Md Shams Shahriar. "Heavy Mineral Analysis of Jamuna River Sediments, Bangladesh." Journal of the Geological Society of India 97.5 (2021): 470-480.
ü Singh, Veerendra, and S. Mohan Rao. "Selective classification of mineral sand slimes in an air fluidized bed." Mineral Processing & Extractive Metallurgy Review 31.2 (2010): 59-72.

 

We thank the reviewer for these additional references and agree that there are many beneficiation studies on separation of heavy mineral sands. We point out however that this paper is a characterisation paper and beneficiation was not the main focus. We will however consider these papers in future beneficiation testwork.

 

Round 2

Reviewer 2 Report

All modifications suggested were incorporated in the paper.

Author Response

There were no further comments from Reviewer#2

Reviewer 3 Report

The authors have incorporated most of the comments raised during the last review.

Author Response

There were no further comments from Reviewer#3