Chemical and Mineralogical Characterization of Montevive Celestine Mineral
, Alejandro B. Rodríguez-Navarro 3,*, Mónica Calero de Hoces 1, Jose Manuel Martin 4 and Mario J. Muñoz-Batista 1,*
Round 1
Reviewer 1 Report
The authors have presented the mineralogical and chemical analysis results of Montevive Celestine Ore. The manuscript shows good analytical data however, the overall conclusion and claims need to be confirmed. I have the following comments/suggestions for the authors.
Line 101-102: TGA and DSC do not validate XRD and XRF analysis. TGA is used to determine the weight loss on thermal heating, while XRD and XRF are used for phase and composition analysis. Also, there is no TGA or DSC data shown in the manuscript.
Which sample was used for SEM and TEM analysis shown in Fig 3 and 4? And how are they representative of different processed and unprocessed materials used in the study?
Line 175-188: Figure A, B, C should be defined in chronological order in the text, i.e. A first, B, C
There is mention of figures as Figure S1, 2,.. I assume these refer to the figures provided in the supplementary information file. But the file is not provided with the manuscript.
There is no XRD spectrum shown in the manuscript. XRD graphs should be included?
Line 414-415 and other relevant places: It is mentioned that “coarser fractions (> 5mm) have a greater concentration of celestine (up to 12 percent units more) due to the selective loss of calcite and other minerals”. As I see in Table 1 (Chemical analysis) – none of the sample shows increase in composition up to 12 %. E60 goes from 63% to 71.5 for E60_6 (8.5% increase), E69 from 70.5 to 67.1 (composition dropped at high particle size), same for E70 E92.
Abstract and other relevant places “We show that low-grade celestine mineral can be concentrated by a low cost 23 and eco-friendly method based on grinding and size separation”. This statement should be justified.
Author Response
We would like to thank the Editor for giving us the opportunity to review and improve our manuscript. All reviewers’ comments have been taken into account and authors have answered all questions. Changes have been incorporated into the revised manuscript using Word track changes tool. We have also prepared a response to each reviewer's comments and suggestions (see below). Additionally, the manuscript has been revised by a native English speaker.
We think that the quality of the paper has greatly improved after the changes suggested by the reviewers were made and hope it is now suitable for publication in Minerals.
REVIEWER 1
The authors have presented the mineralogical and chemical analysis results of Montevive Celestine Ore. The manuscript shows good analytical data however, the overall conclusion and claims need to be confirmed. I have the following comments/suggestions for the authors.
Authors’ reply
We would like to thank the reviewer for his comments and have tried to better define the conclusions. Hereafter, we will respond to each specific comment below.
*Line 101-102: TGA and DSC do not validate XRD and XRF analysis. TGA is used to determine the weight loss on thermal heating, while XRD and XRF are used for phase and composition analysis. Also, there is no TGA or DSC data shown in the manuscript.
Authors’ reply
It seems that the reviewers did not have access to the supplementary material.
We used TGA to determine the amount of carbonate by looking at the weight loss produced in the 650 to 900 C range that correspond to CO2 loss from carbonate thermal decomposition. This data is specific to carbonates and can be used to precisely determine the concentration of carbonate minerals in the sample. This allowed us to validate data (% carbonates) from other methods (XRD and XRF). Santos et al. 2017 [42] cited in this paper, also used the same approach. However, TGA does not yield any information about other mineral phases.
Table S2 (% CaCO3 determined by DXR, XRF and TGA methods) includes the calculated percentage of carbonate mineral determined by XRD, XRF and TGA techniques for comparison. It is of note that there is good correlation between the different techniques.
*Which sample was used for SEM and TEM analysis shown in Fig 3 and 4? And how are they representative of different processed and unprocessed materials used in the study?
Authors’ reply
The images and analysis correspond to E60, which is representative of a low-grade mineral sample.
*Line 175-188: Figure A, B, C should be defined in chronological order in the text, i.e. A first, B, C
Authors’ reply
We have corrected the order in which we describe figures in the main text so they are consistent with the figure legends.
*There is mention of figures as Figure S1, 2,.. I assume these refer to the figures provided in the supplementary information file. But the file is not provided with the manuscript.
There is no XRD spectrum shown in the manuscript. XRD graphs should be included?
Authors’ reply
We included some representative XRD patterns in the supplementary information (Figure S11). However, it seems that this document was not available for the referees.
*Line 414-415 and other relevant places: It is mentioned that “coarser fractions (> 5mm) have a greater concentration of celestine (up to 12 percent units more) due to the selective loss of calcite and other minerals”. As I see in Table 1 (Chemical analysis) – none of the sample shows increase in composition up to 12 %. E60 goes from 63% to 71.5 for E60_6 (8.5% increase), E69 from 70.5 to 67.1 (composition dropped at high particle size), same for E70 E92.
Authors’ reply
The comparison should be made between samples EXX_1 to EXX_6 as it is now detailed in the manuscript.
E60, E69 and E92 without suffix correspond to bulk samples prior to particle size separation.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The authors developed research involving the sampling, laboratory testing, and characterization of Montevive Celestine ore from the mine, waste dumps, and tailings. I found major issues with the lack of information and writing style. I hope you find my comments and suggestions constructive.
L3 Ore from the mine, the waste dumps, and tailings appear to have been homogenized for analysis in the laboratory. If so, do you believe that the word "Celestine Ore" in the title reflects the sources of samples that were analysed?
L8 Change the font size.
L13-L15 Abstract provides a clear summary of the problems, which would have been the central focus of this research and been given in the introduction section together with the importance of research. The high-grade mineral is separated manually or by dry screening, and substantial amounts of uneconomical low-medium minerals (50–65%) are dumped in the mine tailings. In my opinion, it is the chemical and mineralogical characterizations of Montevive Celestine ore from mines, waste dumps, and tailings that are required in order to make mine operations more sustainable by reducing waste dumps and pollutants associated with tailings.
L23-L24 I agree that size separation and grinding are beneficial. However, the way the results are currently presented, especially in the figures and tables, does not strongly support the claim.
L39 …Granada, Spain) [8-12].
L41-L86 The geological and some mineralogical details of the area that was used as a sampling site are given, with findings shown in Figure 1. This style, in my opinion, contradicts the requirement that the introduction section establishes the background for the investigation, clarifies the research problem, and identifies the study’s goal. The introduction should have included a "why" for each of the following: why the authors chose the topic for research; why it is important; why a particular technique or strategy is important; and so on. The paragraph in which a claim of celestine as an economically important mineral in the European Union and chemical industry is indicated, but the knowledge gap that the rest of the research will fill is not clearly shown. Additionally, the study's true objective is to fully investigate mineralogy using cutting-edge analytical methods and equipment. In my opinion, it would be more interesting if goals included a comparison of ore from the mine, waste dumps, and tailings to fully understand the importance of grounding and size separation and the environmental concerns linked to mining strontium.
L45-L64 Figure 1 obviously supports the literature. Why is it not included in the materials and methods or results sections, or as supplemental information, if it is a part of your analyses?
L68-L80 It is obvious that Figure 1 allows you to confirm, with your perspective on the literature, that Montevive stromatolite was originally carbonate stromatolite. Could you explain the reasons for such a debate in the introduction? I think it would be more effective if Figure 1 was presented alongside your findings, and you then had a discussion by outlining your point of view in the Discussion section.
Line 118 It is clearly indicated that the ore from the mine, waste dumps, and tailings were sampled. Have you homogenized ore from the mine, waste dumps, and tailings for laboratory testing? If so, how many samples were produced and in what ratios did they mix to make the test?
L118-L123 Please provide a brief description of the sampling site(s), including information such as the location of the Celestine ore mine, waste dump locations, and tailings. As long as information is evidently present in other paragraphs, a summary of the material and methods is not needed.
L119 "Semi-industrial equipment" seems to be a broad word. Additionally, it is unclear what equipment was used to obtain the samples that were analysed. In my opinion, it is preferable to be more explicit and provide details such as the name of the equipment with a model number, the manufacturer's name, city, and country.
L125-L127 What about waste and dumps tailings if there were three main types of celestine ore selected for the research? In my opinion, this statement is ambiguous, it simply indicates that you had analysed six mined ore samples.
L126-L127 1) A medium grade material (E60, 125, and E69); 2) a high grade preconcentrated mineral (E92); 3) Unprocessed mineral samples with intermediate grades (E70, E80, E90) (Figure S1-S3).
L131 Use a style like instrument name (model, firm, city, country).
L130-L135 Which of the two a short dash (en dash) or a hyphen is correct?
L171 Please confirm the unit "µm" is correct.
L172 The number "60" should be separated from the unit "ºC" by a space.
L173 It is crucial in quantitative research to keep your interpretation of the results (discussion) separate from the objective findings (results).
L174 It is not a smart idea to include subheads that list various methodologies employed in the experiment. I suggest using subheads that reflect your goals and insight into the research's significance, limitations, and future research directions.
L175-L176 If you just state something like, "Optical microscopy was used to analyse the distribution of mineral phases," it might be easier for people who read your paper to understand what you mean.
L177 Remove the space after the number "69"and unit "%."
L354 I remain cautious about the number of samples analysed (n), groups of samples, and implication of this research. Could you provide a summary of the chemistry and mineralogy of the Montevive celestine ore from the mine, in waste dumps and tailings?
Author Response
We would like to thank the Editor for giving us the opportunity to review and improve our manuscript. All reviewers’ comments have been taken into account and authors have answered all questions. Changes have been incorporated into the revised manuscript using Word track changes tool. We have also prepared a response to each reviewer's comments and suggestions (see below). Additionally, the manuscript has been revised by a native English speaker.
We think that the quality of the paper has greatly improved after the changes suggested by the reviewers were made and hope it is now suitable for publication in Minerals.
REVIEWER 2
The authors developed research involving the sampling, laboratory testing, and characterization of Montevive Celestine ore from the mine, waste dumps, and tailings. I found major issues with the lack of information and writing style. I hope you find my comments and suggestions constructive.
Authors’ reply
We would like to thank the reviewer for their comments as they have greatly helped us improve the quality of the manuscript. We have added additional information about sampling sites and mineral processing. The text has been revised by a native English speaker. Regarding specific comments, please find our answers below.
*L3 Ore from the mine, the waste dumps, and tailings appear to have been homogenized for analysis in the laboratory. If so, do you believe that the word "Celestine Ore" in the title reflects the sources of samples that were analysed?
Authors’ reply
We have changed “Celestine ore” for “Celestine mineral” throughout the text.
*L8 Change the font size.
Authors’ reply
Done.
*L13-L15 Abstract provides a clear summary of the problems, which would have been the central focus of this research and been given in the introduction section together with the importance of research. The high-grade mineral is separated manually or by dry screening, and substantial amounts of uneconomical low-medium minerals (50–65%) are dumped in the mine tailings. In my opinion, it is the chemical and mineralogical characterizations of Montevive Celestine ore from mines, waste dumps, and tailings that are required in order to make mine operations more sustainable by reducing waste dumps and pollutants associated with tailings.
Authors’ reply
A comment has been added to the main manuscript related to this item:
“Currently, the mine has a large amount of tailings resulting from the rejection of a manual dry screening of high grade celestine ores. This visual and density screening was done in the early days of mining (1954-1973).”
Concentrating the celestine ore and increasing the ore recovery rate would reduce the mine's water and energy consumption. This would avoid blasting and stripping, displacement of earth, generation of new tailings and reduced fuel consumption. The impact on the environment would be minimized, making the mining operation more sustainable and environmentally friendly
*L23-L24 I agree that size separation and grinding are beneficial. However, the way the results are currently presented, especially in the figures and tables, does not strongly support the claim.
Authors’ reply
We have tried to better explain these results.
*L39 …Granada, Spain) [8-12].
Authors’ reply
Done.
L41-L86 The geological and some mineralogical details of the area that was used as a sampling site are given, with findings shown in Figure 1. This style, in my opinion, contradicts the requirement that the introduction section establishes the background for the investigation, clarifies the research problem, and identifies the study’s goal. The introduction should have included a "why" for each of the following: why the authors chose the topic for research; why it is important; why a particular technique or strategy is important; and so on. The paragraph in which a claim of celestine as an economically important mineral in the European Union and chemical industry is indicated, but the knowledge gap that the rest of the research will fill is not clearly shown. Additionally, the study's true objective is to fully investigate mineralogy using cutting-edge analytical methods and equipment. In my opinion, it would be more interesting if goals included a comparison of ore from the mine, waste dumps, and tailings to fully understand the importance of grounding and size separation and the environmental concerns linked to mining strontium.
Authors’ reply
The purpose of this study is to define more appropriate separation methods for each type of mineral present in different areas of the mine. However, to define the effectiveness of the concentration method (based on grounding and size separation), it is necessary to accurately characterize the mineral composition in the original and processed mineral samples. We used complementary analytical techniques such as optical (OM) and scanning and transmission electron microscopy (SEM, TEM), energy dispersive X-rays (EDX), X-ray fluorescence (XRF) and X-ray diffraction (XRD) to fully characterize the morphology, microstructure, chemistry and mineralogy of the celestine mineral. We compared the information provided by each technique and discuss the advantages and disadvantages of each one. In the mine, only XRF is used for quality control of the Celestine mineral. This study serves to verify the quality of XRF analysis and to explore other analytical techniques to determine which is more adequate for quality control. We conclude that XRD Rietveld analysis can be more precise and faster for mineral characterization. TGA analysis was specifically useful as an independent technique to verify the estimation of carbonate minerals. Other methods based on optical and electron microscopy are very useful and informative but more expensive and time consuming.
*L45-L64 Figure 1 obviously supports the literature. Why is it not included in the materials and methods or results sections, or as supplemental information, if it is a part of your analyses?
Authors’ reply
We have included it in the material section to describe the raw mineral.
*L68-L80 It is obvious that Figure 1 allows you to confirm, with your perspective on the literature, that Montevive stromatolite was originally carbonate stromatolite. Could you explain the reasons for such a debate in the introduction? I think it would be more effective if Figure 1 was presented alongside your findings, and you then had a discussion by outlining your point of view in the Discussion section.
Authors’ reply
We discuss it in the main text.
*Line 118 It is clearly indicated that the ore from the mine, waste dumps, and tailings were sampled. Have you homogenized ore from the mine, waste dumps, and tailings for laboratory testing? If so, how many samples were produced and in what ratios did they mix to make the test?
We have included a more detailed description of the sampling sites and mineral processing in the material and method section.
*L118-L123 Please provide a brief description of the sampling site(s), including information such as the location of the Celestine ore mine, waste dump locations, and tailings. As long as information is evidently present in other paragraphs, a summary of the material and methods is not needed.
Authors’ reply
See previous point
L119 "Semi-industrial equipment" seems to be a broad word. Additionally, it is unclear what equipment was used to obtain the samples that were analysed. In my opinion, it is preferable to be more explicit and provide details such as the name of the equipment with a model number, the manufacturer's name, city, and country.
Authors’ reply
We have provided more details regarding the instrumentation used to process the mineral in the material and methods section.
L125-L127 What about waste and dumps tailings if there were three main types of celestine ore selected for the research? In my opinion, this statement is ambiguous, it simply indicates that you had analysed six mined ore samples.
Authors’ reply
A more detailed description of sampling sites and mineral samples has been included in the materials and method section.
L126-L127 1) A medium grade material (E60, 125, and E69); 2) a high grade preconcentrated mineral (E92); 3) Unprocessed mineral samples with intermediate grades (E70, E80, E90) (Figure S1-S3).
Authors’ reply
See previous points.
L131 Use a style like instrument name (model, firm, city, country).
Authors’ reply
Done.
L130-L135 Which of the two a short dash (en dash) or a hyphen is correct?
Authors’ reply
Done.
L171 Please confirm the unit "µm" is correct.
Authors’ reply
Yes.
L172 The number "60" should be separated from the unit "ºC" by a space.
Authors’ reply
Done.
*L173 It is crucial in quantitative research to keep your interpretation of the results (discussion) separate from the objective findings (results).
Authors’ reply
This study is mainly methodological and we think it is more adequate to present the result and discussion together for each analytical technique used here.
*L174 It is not a smart idea to include subheads that list various methodologies employed in the experiment. I suggest using subheads that reflect your goals and insight into the research's significance, limitations, and future research directions.
Authors’ reply
See previous point.
*L175-L176 If you just state something like, "Optical microscopy was used to analyse the distribution of mineral phases," it might be easier for people who read your paper to understand what you mean.
Authors’ reply
Microscopy is used to show the spatial distribution and/or association of minerals.
L177 Remove the space after the number "69"and unit "%."
Authors’ reply
Done.
L354 I remain cautious about the number of samples analysed (n), groups of samples, and implication of this research. Could you provide a summary of the chemistry and mineralogy of the Montevive celestine ore from the mine, in waste dumps and tailings?
Authors’ reply
Ok. This information is included in Table 2 and Table 3.
Author Response File: Author Response.docx
Reviewer 3 Report
The authors present a way to use physical techniques in the characterization of a celestine sample, in order to obtain information on the origin of the sample, its natural associations and the identification of other mineral phases in lower concentration. Based on this information, a physical separation process by particle size is proposed to increase the concentration of the celestite mineral and thereby reduce the costs of strontium extraction. Although the results show a solid methodology and excellent work, the following questions arise:
1. Why is grinding and size separation considered an economical and environmentally friendly method?
2. What method do you suggest for applying the method to high-grade minerals (about 90% celestite)?
3. Of the characterization techniques mentioned in this work, which do you consider the most important and necessary to achieve the objective of this study?
Author Response
We would like to thank the Editor for giving us the opportunity to review and improve our manuscript. All reviewers’ comments have been taken into account and authors have answered all questions. Changes have been incorporated into the revised manuscript using Word track changes tool. We have also prepared a response to each reviewer's comments and suggestions (see below). Additionally, the manuscript has been revised by a native English speaker.
We think that the quality of the paper has greatly improved after the changes suggested by the reviewers were made and hope it is now suitable for publication in Minerals.
REVIEWER 3
The authors present a way to use physical techniques in the characterization of a celestine sample, in order to obtain information on the origin of the sample, its natural associations and the identification of other mineral phases in lower concentration. Based on this information, a physical separation process by particle size is proposed to increase the concentration of the celestite mineral and thereby reduce the costs of strontium extraction. Although the results show a solid methodology and excellent work, the following questions arise:
Authors’ reply
We appreciate the reviewer’s comments and we have answered each point hereafter.
- Why is grinding and size separation considered an economical and environmentally friendly method?
Authors’ reply
It is a physical method that does not use any chemical treatment, making it more economical and environmentally friendly.
- What method do you suggest for applying the method to high-grade minerals (about 90% celestite)?
Authors’ reply
In this case, there is no benefit to processing this high-grade mineral. It would be better to not process it at all and sell it as it is.
- Of the characterization techniques mentioned in this work, which do you consider the most important and necessary to achieve the objective of this study?
Authors’ reply
Off all the techniques used, the most useful was XRD quantitative analysis based on Rietveld method. It does not require standards, it is fast, accurate and provides information that could not be determined by implementing other techniques. See comments above.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The authors have made significant corrections to the manuscript and added the necessary information. I have no further comments.
Author Response
We thanks the reviwer for his help revising the manuscript.
Reviewer 2 Report
Overall, this is a clear, concise, and well-written manuscript. There are only two minor issues that the authors should double-check. Once these issues are addressed, the article can be published.
L132–L135: The sentence “the studied material was provided by the company Canteras Industriales that exploits Mina Aurora in the Montevive deposit” should be deleted considering similar information is displayed in Materials and Methods (L210–L211). The new sentence would then be “Representative celestine mineral samples ranging in purity from 60% to 92.0% celestine were analysed.”
L146–L208 This information makes it easier to understand the nature of mineral samples. Therefore, it is enjoyable to provide the description of the ore body at Montevive with a particle heading.
Author Response
We appreciate the comments of the reviewer and have made the suggested changes.
L132–L135: The sentence “the studied material was provided by the company Canteras Industriales that exploits Mina Aurora in the Montevive deposit” should be deleted considering similar information is displayed in Materials and Methods (L210–L211). The new sentence would then be “Representative celestine mineral samples ranging in purity from 60% to 92.0% celestine were analysed.”
ANSWER: We have removed the first sentence and modified the second one as suggested.
L146–L208 This information makes it easier to understand the nature of mineral samples. Therefore, it is enjoyable to provide the description of the ore body at Montevive with a particle heading.
ANSWER: We agree with the reviewer and have added a "2.1 Celestine ore" heading within the material and method section. We have also renumbered the other headers in this section accordingly.
