Optimization of Flotation Conditions for Long-Flame Coal Mud by Response Surface Method
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe introduction is incomplete, more information is missing.
Must include references on the low flotation of kaolin, calcite and quartz.
Must indicate the characteristics of the collector used.
Must indicate the charactaristics of the foaming agents used.
The discussion of the results obtained is missing in the figures 4 and 5.
The results of tables 6 and 7 need to be discussed.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors
1. The links in Introduction are not formatted properly. Theu should be highlighted with the use of square brackets.
2. In Introduction, not all factual information and theses, including numerical data, are supported by references to the literature. In addition, the quantity of publications analyzed in the review is extremely small.
3. Authors should pay attention to the design of images, especially the lack of uniformity in text design (axis labels and units of measurement, heterogeneity of sizes, etc.), for example, transmittance/%, Wavenumber/cm-1 (Fig. 1) vs. 2θ/(°) (Fig. 2).
4. In Figure 3, it is necessary to label all visible elements.
5. The equipment used and analysis modes must be described when mentioning the corresponding methods. For example, the description of the XRD method should include the type of X-ray diffractometer, radiation (λ = …), the scanning range, exposure time, step, etc.
6. The results of XRD analysis are presented in low quality. The database for crystalline phases is not indicated. All accepted crystalline phases must be indicated in a standard form (JCPDS card numbers, chemical formulas of compounds, etc.). In the XRD patterns, please indicate the Miller indices for all identified intensity maxima of all crystalline phases. In addition, the authors did not identify peaks that appear to be significant enough (for example, 34, 35, 42, 47, 50-85 deg and others). By the way, it is the presence of such peaks and their intensity that can indicate the purity of the product as well as the content of various impurity crystalline phases.
7. It is hardly possible to draw any conclusions about the properties of the materials under study without specific information about the composition. Based on the above comments and more precise information about the composition, the authors need to talk about the influence of impurities on the achieved properties. It is necessary to carry out standard elemental composition studies using XRF or EDS. Such results are usually presented in the form of a table of the mass content of all elements, and this is the form in which the authors should present this information.
8. The article lacks information about the microstructure, which can significantly determine the properties under study.
9. A clear relationship should be provided between the composition and structure of materials and the resulting properties (Results and Discussion, Conclusions).
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors investigated the influencing factors for a flotation process of long-flame coal. They then optimized the flotation process by using the response surface method.
First, the coal samples were characterized in terms of elemental composition, the particle size and the functional groups (FTIR). XRD was used to study the mineral composition of the coal, revealing that the main mineral is kaolinite. The contact angle of the coal was determined to be 42°. The optimal slurry concentration, the amount of trapping agent as well as the amount of frothing agent was determined in single-factor flotation experiments. Based on the results, a three-level response surface method experimental design was proposed and the modeling results were discussed. It could be shown that the presented models are very precise and can be used to analyze the influencing factors of the flotation process. Finally, a response surface analysis of both established models was performed and the resulting optimal flotation conditions were experimentally validated.
1. Lines 28-33: Is there a literature reference for this? In general, more literature references in the introduction would be welcome.
2. Table 1: What do the variables M_ad, A_ad and FC_ad mean? It is not stated in the text.
3. Which measurement technique was used to determine the elemental composition (Table 2)?
4. Lines 156-157: Previous sentence was repeated.
5. Line 172: Maybe find another heading for Chapter 2.3., as it is the same as that of Chapter 2.2. Shoudn't it be "Multi-Factor Tests"?
6. Line 196: I would suggest to stay consistent with the technical terms thoughout the paper: forming agent/frothing agent and trapping agent/capture agent.
7. What does ANOVA stand for?
8. An outlook and commenting on the relevance of the work in the conclusion section would be welcome.
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThe manuscript presented a study investigating influential factors on the long-flame coal flotation. Laboratory tests were performed using Design of Experiment and the influence of the factors were investigated using correlation and response surface analysis. The reviewer has some questions regarding the analysis results and the conclusions. In addition, the language and writing of the manuscript must be improved.
Below lists questions/comments from the reviewer:
1. Please change the citation format to more accepted standard. You can use the Author-Year format or Numbering format with the bracket (eg. [1], [2]...).
2. Please use standard terms, some examples include:
2.1 Page 3, Line 90: 'following 0.25mm' should be '-0.25mm' or 'below 0.25mm'.
2.2 Page 3, Table 3: 'Agricultural Productivity' should change to 'Cumulative Passing'.
2.3 Page 4-5: change 'trapping agent' and 'Capture agent' to 'collector', 'frothing agent' and 'foaming agent' to 'frother'.
2.4. Page 5, Line 149: One-way test? Page Line 165: 'Flotation perfection index'? 'Flotation Refinement index'?
2.5 Page 9, Line 253: 'Reverse adsorption layer'?
2.6 Page 10, Line 270: 'the degree of flotation refinement' change to 'the performance of flotation concentration'.
3. Page 8, Table 5: The results from test 13-15 cannot repeat well. This is very concerning, as this could indicate poor quality of the obtained E and G data and therefore rendering the conclusions questionable.
4. Page 7, Line 194 to 200: You cannot compare absolute values of the coefficient to tell the significance of the factors, because the scale of the factor values can be different.
5. Page 11, Line 288: The merit of the this research is limited considering the results were not validated in actual operations.
Comments on the Quality of English Language
The language quality of the manuscript is poor. One major issue is not using standard technical terms. Examples have been given in the comments above.
There are also multiple grammar mistakes which need to be corrected.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors have considered the comments carefully and tried our best to revised the manuscript accordingly. I can accept the manuscript now.
Author Response
Dear reviewer:
Thank you for your professional review of our manuscript, as well as your constructive comments and valuable suggestions. This is because these important points you make make our manuscript better. I'm honored to receive your recognition of my work.
Thank you and best regards.
With regards
Lin Fang Ao
E-mail: [email protected]
Corresponding author:
Name: Zhang Hongbo, E-mail:[email protected]
Name: Zhang Jingkun, E-mail:[email protected]
Reviewer 4 Report
Comments and Suggestions for AuthorsRegarding the previous comment that the results from test 13-15 cannot repeat well, the response from the authors is not satisfactory. Table 6 showed that the E values for the three repeated tests (under the same A, B and C testing conditions) were 36.0, 30.2, 34.4, and the F values were 14.85, 13.42 and 14.17. These indicated large errors associated with the values. The errors could from multiple sources, including systematic errors from operators, sample analysis, etc. With such significant errors, it can be questionable to conclude that the optimization results are true. Error analysis on model prediction results must be conducted to get a sense of confidence in the results.
Comments on the Quality of English Language
The non-standard terms used in the article are still an issue. To name a few, 'small sieve test' can be changed to 'sieving analysis' or 'screening analysis'; 'grain size' can be changed to 'particle size'; 'proportions' can be 'fractional distribution'; what do you exactly mean by 'flotation refinement index' , can you give definition and it could be much easier to use a common term that mineral processors accept.
Author Response
please see the attachment.
Author Response File: Author Response.pdf
