Statistical Modeling of NaCl and FeSO4 Pretreatment Effect on Refractory Copper Ore Leaching
, Manuel Saldana 2, Norman Toro 2, Mauricio Mura 2,3, Ignacio Castillo 2, Alexis Guzmán 1, Edelmira Gálvez 4 and Rossana Sepúlveda 1,*Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe article is devoted to modeling the Copper Ore leaching process. There is no doubt that this issue is of practical interest. I can recommend the article for publication but after making a number of corrections:
1. The term "leaching kinetics" in the title of the article is incorrect. The authors should talk not about kinetics but about the degree of leaching. The kinetic parameters of the leaching process were not studied in this article! The purpose of the work is also incorrectly formulated (line 192): “The aim was to study the effects of time, acid consumption, NaCl, and FeSO4 on the leaching kinetics”. The term "leaching kinetics" is incorrect here.
2. The article only states that "the chemical composition shows 0.76 % of total copper and 0.67 % of soluble copper" (line 143). However, the total chemical composition of the ore is not given in the article! The phase composition of the ore is listed, but not even the approximate mineral content is indicated (line 146).
3. In Line 136 the authors indicate that the article will also study “the synergistic effects of NaCl and FeSO4 on the dissolution of MnO2”. However, the article does not present experimental data on the dissolution of MnO2! Based on literature data, it was stated that adding a suitable reducing agent, such as Fe(II), can significantly improve the dissolution process of MnO2 and Mn2O3. However, where is the experimental evidence for this conclusion?
4. What is the hypothesis behind the idea of ​​using NaCl additives to ore? There is nothing about this in the article! The use of sodium chloride in the acid leaching process needs to be justified. The article should describe what is the role of chloride ions!
5. The article does not provide an equation for calculating the parameter called "sulfation" by the authors.
6. The abbreviation AAC is not clear. Can the abbreviation be used in the abstract of the article? What is analytical acid consumption? What does "consumption" mean in the context of the leaching experiment methodology? The point is that acid with a given initial concentration was fed into a column with ore and its consumption was not studied. Why not use the term "acid solution concentration"?
7. The article does not describe in detail the methodology for conducting the leaching experiments. It is stated that leaching was carried out in columns and the irrigation of the ore within these columns was carried out using peristaltic pumps. However, it is not stated at what speed the acid solution moved through the ore layer in the column.
8. The article states that “all column leaching tests planned in Table 2 were performed in duplicates”, but the data for each measurement are not presented. These data are important for assessing the degree of reproducibility of the obtained data!
9. The text of the article (line 191) states that five factors were used for modeling. However, there were not five, but four factors! In Table 1 factors x3 and x4 are designated as x4 and x5.
10. Lines 167-172 – sulfation test procedure is described with the mass of ore, volume water and washed water!? The experimental procedure does not say anything about the use of water and washed water! How to understand 269.758 ml of water (Line 171)? How was its volume measured to an accuracy of 0.001 ml? Why is it not specified what volume of acid was used in the leaching experiments?
11. According to Fig. 1, sodium chloride additions increase the sulfation result from 14 (leaching without NaCl) to 20%. How to understand the conclusion (line 364) that “While the presence of NaCl was statistically significant, variations in its levels did not yield significant differences”. This conclusion seems incorrect.
12. It was concluded (line 366) that no statistically significant differences were detected among the levels of FeSO4 sampled. Then why was it concluded that in order to achieve the optimal sulfation value, it is necessary to use exactly 42 g of FeSO4 (line 372), and not less?
13. The last paragraph of the article (Line 373-383) must be completely removed from the article! Do the authors have ideas on how to improve their research? Then let them improve it and then send the improved results for publication! Otherwise, the reviewer should not recommend the article for publication, but recommend conducting additional research to "increase the depth and accuracy of understanding of the leaching process under study"!
Author Response
Dear Reviewer,
The answers to your suggestions can be found in the attached file. We thank you for your comments, which allowed us to improve the document.
Thank you very much for your feedback.
Rossana Sepúlveda
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsBlack copper oxides, a significant copper resource, present challenges in leaching due to their refractory nature and complex mineralogical composition. In the manuscript, response surface methodology was used to study the influences of time and the addition of NaCl and FeSO4 on sulfation behavior during the reductive leaching of black copper ores. The research content of this manuscript has certain novelty. However, the data of the manuscript is not comprehensive, and the logic of the manuscript writing is incomplete, so it is recommended to make major revisions before received. There are some suggestions for improvement.
1. What scientific question can the research component address in the manuscript? Please add the purpose of the study in the abstract.
2. It is mentioned in the abstract that the kinetics of sulfation during reductive leaching of black copper ores was studied, but there is no kinetic model for the reaction rate constants (K) in the manuscript. There are also no results on the kinetic behaviors obtained using Arrhenius equation. Please add.
3. In the abstract, AAC is presented. Please add what AAC is.
4. What is the significance of the research in this manuscript? What are the advantages of this study in comparison with other studies that have been reported? Please add this in the introduction.
5. On page 3, in section 2.1, please add the elemental composition and elemental content of the ore.
6. On page 4, in section 2.1, the X-ray diffraction of the ore sample is tested in the manuscript. Please present the test result in the form of a picture. And make sure the results for the ore sample correspond to the PDF card.
7. The Notation in Table 1 and Table 2 is inconsistent. Please correct it.
8. Figure 1 shows the effects of the sulfation experiment. Why is the effect of time measured 5 data points, the effect of AAC% 3 data points, and other effects 4 data points? Set the value to five data points to ensure accuracy.
9. In Table 4, the fits of R2, R2 (adjust.) and R2 (predict.) are all too low. This does not guarantee the accuracy of the model results. Please explain in detail. If possible, please redo the experimental data to reduce the error
Author Response
Dear Reviewer,
The answers to your suggestions can be found in the attached file. We thank you for your comments, which allowed us to improve the document.
Thank you very much for your feedback.
Rossana Sepúlveda
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThis study uses a multiple linear regression model and response surface methodology to analyze the effects of time, NaCl, and FeSO4 addition on sulfidation behavior. I have the following revision suggestions for the manuscript and request the authors' responses:
1. The introduction is somewhat lengthy. It is recommended that the authors further condense the key information, focusing on the research background, scientific issues, and innovative points, while avoiding excessive unnecessary background information, in order to improve the logical flow and readability of the article.
2. In Section 2.3, the description of the statistical modeling methods is quite detailed but lacks emphasis on the core elements of the modeling process. It is suggested that the authors streamline the introduction of methods, focusing on the specific process of modeling, parameter selection, and their relevance to the research questions to enhance the content's focus and practicality.
3. The data in Table 2 occupies a large portion of the manuscript, and directly placing it in the main text contributes little to the expression of the manuscript’s main idea. It is suggested to organize the data from Table 2 into an appendix and upload it separately, leaving only the key data and analytical results in the main text to streamline the manuscript and highlight key content.
4. The overall layout of the manuscript needs improvement. Currently, the image sizes are disproportionate, which may affect the reading experience. It is recommended to adjust the layout of the images and text, ensuring more uniform image sizes, a reasonable proportion relative to the text, and clear image resolution, while also distributing the images appropriately across the relevant sections to improve the manuscript's overall visual effect and professionalism.
5. There is an error in the figure number of Figure 8 in line 324. It is recommended that the authors check the consistency of figure labels with text references and ensure that the title, caption, and references to Figure 8 in the text are correctly aligned, in order to avoid confusion and improve the rigor and accuracy of the manuscript.
6. The application of response surface methodology is a highlight of the manuscript, but the analysis of the response surface plots is currently too simplistic, lacking in-depth discussion and not fully supporting the research conclusions. It is suggested that the authors provide a detailed interpretation of key features in the response surface plots, such as main effects, interaction effects, and their significance, and discuss their implications for the research objectives, in order to enhance the depth and persuasiveness of the analysis.
7. The conclusion section is somewhat lengthy. It is recommended that the authors further condense the content, highlighting the core research findings and their scientific significance. Avoid repeating analytical details from the main text and focus on summarizing the innovations and main contributions, while explicitly addressing the practical application value of the research and future research directions, to improve the conciseness and impact of the conclusion.
Author Response
Dear Reviewer,
The answers to your suggestions can be found in the attached file. We thank you for your comments, which allowed us to improve the document.
Thank you very much for your feedback.
Rossana Sepúlveda
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors responded very carefully to each comment. The manuscript was revised according to the suggestions. The revised manuscript is scientifically based and logical. This revised manuscript can be accepted directly.
Reviewer 3 Report
Comments and Suggestions for AuthorsBased on the previous round of feedback, the authors have made substantial revisions and additions to the paper, addressing my comments thoroughly and significantly improving the overall quality of the manuscript.
The revised version is clear, well-structured, and provides sufficient evidence to support the findings. I believe the paper is now suitable for publication, and I recommend its acceptance.
