Electrical Resistance as an Aggregate Characteristic of Coke Properties for Electrochemical and Coke Production

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors discuss whether electrical resistivity of coke can be used as an indicator for coke quality control. Although the range of applicability is limited, the basic information may be useful to readers. 

There are some questions as follows.

1. The explanation of the vertical and horizontal axes in Figure 6 is insufficient, making it difficult to understand. Please add explanation.

2. Do the "Total moisture", "Plastometric parameters", and "Content of vitrinite" in Table 2 have any relation to electrical resistivity? Is it not necessary to consider the effects of the specific surface area of pores in coal and the alkalinity of ash on electrical resistivity?

3. The explanation of why Equation 8 and Equation 9 can be used to estimate the properties of coal from electrical resistivity is not clear, so please add explanation. (*In Figure 11, the electrical resistivities of batches 2 to 4 and 10 to 17 are almost the same.)

 

Author Response

1. The explanation of the vertical and horizontal axes in Figure 6 is insufficient, making it difficult to understand. Please add explanation.

Answer: Thanks for the comment, we have corrected the name of the axis in the figure.

2. Do the "Total moisture", "Plastometric parameters", and "Content of vitrinite" in Table 2 have any relation to electrical resistivity? Is it not necessary to consider the effects of the specific surface area of pores in coal and the alkalinity of ash on electrical resistivity?

Answer: Thank you for your question. The listed indicators are important characteristics of coal raw materials. The thickness of the plastic layer characterizes the sinterability of coal concentrates and allows us to estimate the impact on the overall sinterability of the charge of low-sintering components, the quantitative effect of which on the electrical resistance of coke is considered in this paper. In addition, a close relationship between the vitrinite reflection index and the coke resistivity was established, which is characterized by the equations obtained in this work. The effect of ash content is considered and characterized by Equation 3. The influence of the chemical composition of the mineral part, the ash basicity index, and the pore surface has not been studied and will be a promising area for further research.

3. The explanation of why Equation 8 and Equation 9 can be used to estimate the properties of coal from electrical resistivity is not clear, so please add explanation. (*In Figure 11, the electrical resistivities of batches 2 to 4 and 10 to 17 are almost the same.)

Answer: Equation 8 characterizes the influence of coal parameters (degree of vitrinite reflection, sulfur content, ash content, volatile matter yield) on the electrical resistance of coke. In fact, it is a complex indicator. Thus, in a situation where it is necessary to produce coke with specified characteristics, Equation 8 can be used to select coal raw materials with optimal parameters. In Figure 11, batches 2-4 and 10-17 have almost the same electrical resistance and reactivity, which is explained by similar characteristics of the coal batches (average ash content, vitrinite reflectance, etc.).

Reviewer 2 Report

Comments and Suggestions for Authors

Electrical resistivity as a cumulative characteristic of coke properties

Review

In this paper is studied the influence of the composition of coal batches and the final temperature of the coking process on the resistivity of coke. The resistivity and reactivity are influenced by temperature level and coke properties. This is important when using coke in electrothermal processes, since the productivity, electrical and thermal efficiency of the furnace depends on the coke electrical resistivity.

The article is interesting. However, some information and clarifications would improve the final version.

1.     The novelty of the research should be more evidently defined.

2.     The state of the art must be enriched.

3.    How exactly are computed the characteristics from Tables 5 and 6? The computational method must be clearly explained.

4.  A comparison with other results from relevant publications would validate the study.

5.    The Conclusions must show recommendations: how to use the coke in electrothermal processes to become more efficient.

6.     The measuring unit “Ohm” should be instead of “Om” (in lines 129-130).

Comments on the Quality of English Language

English language must be edited for syntax, and style.

 

Author Response

In this paper is studied the influence of the composition of coal batches and the final temperature of the coking process on the resistivity of coke. The resistivity and reactivity are influenced by temperature level and coke properties. This is important when using coke in electrothermal processes, since the productivity, electrical and thermal efficiency of the furnace depends on the coke electrical resistivity.

The article is interesting. However, some information and clarifications would improve the final version.

1. The novelty of the research should be more evidently defined.

Answer: Thank you, we have made changes to the text.

2. The state of the art must be enriched.

Answer: In the discussion section, we made the following changes to the text.

3.   How exactly are computed the characteristics from Tables 5 and 6? The computational method must be clearly explained.

Answer: The reactivity and post-reaction strength of coke were determined by the method ISO 18894:2006 "Coke. Determination of coke reactivity index (CRI) and coke strength after reaction (CSR)", and the electrical resistance by the method DSTU 8831:2019 Coke. Method for determination the resistivity coal coke powder. The obtained values were listed in Table 5. The correlation coefficients shown in Table 6 were obtained using the Excel program.

1. A comparison with other results from relevant publications would validate the study.

Answer: Thank you for your comments. Comparison with other results from relevant publications is given in the discussion section. Corresponding changes were made to the text.

 

2. The Conclusions must show recommendations: how to use the coke in electrothermal processes to become more efficient.

 

Answer: Thank you for your comments. The recommendations in the conclusions relate to the possibility of optimizing the component composition and properties of coal raw materials to produce coke with a given electrical resistivity value. We also added the practical and economic significance of the research, which is that as the resistivity test requires much less time to perform than the reactivity test, it can be considered as an alternative approach to reactivity testing currently performed for quality control purposes. Corresponding changes were made to the text.

6. The measuring unit “Ohm” should be instead of “Om” (in lines 129-130).

Answer: Thank you, we have made changes to the text.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors,   I appreciate the efforts of the authors who addressed the issue of the electrochemical properties of coke. However, there are several formal errors in the work that I have comments on. The inconsistency in the way equations, figures, and tables are referenced is very distracting. In one line, you write Fig. X, and in the next, Figure X; the same applies to equations and tables.   It is also necessary to unify the notation of quantities in the work; they should be written in italics throughout the entire document. I also ask the authors to correct the spaces between the number and the unit – the work contains two forms of notation: XX% and XX %. This applies to various units.   In Table 3, you have the unit M³ listed; please explain this to the authors. Figure 2 needs to be corrected. In the text, there is a value of 3,000. Since the authors did not separate numbers with a comma anywhere else after this value, please explain or correct this.   Regarding the content, I also have several reservations and questions. Under Figures 11 and 12, you state that you recommend the mentioned equation because the differences from the actual values are small. However, Figure 12, on the contrary, suggests significant differences.   I also had trouble verifying the described results with the values in the graphs and tables. I recommend making the presentation of the results clearer. In the discussion, please provide an analogy between the results according to reference 10 and the results in works 27-29.

Author Response

Dear authors,   I appreciate the efforts of the authors who addressed the issue of the electrochemical properties of coke. However, there are several formal errors in the work that I have comments on. The inconsistency in the way equations, figures, and tables are referenced is very distracting. In one line, you write Fig. X, and in the next, Figure X; the same applies to equations and tables.   It is also necessary to unify the notation of quantities in the work; they should be written in italics throughout the entire document. I also ask the authors to correct the spaces between the number and the unit – the work contains two forms of notation: XX% and XX %. This applies to various units.   In Table 3, you have the unit M³ listed; please explain this to the authors. Figure 2 needs to be corrected. In the text, there is a value of 3,000. Since the authors did not separate numbers with a comma anywhere else after this value, please explain or correct this.   Regarding the content, I also have several reservations and questions. Under Figures 11 and 12, you state that you recommend the mentioned equation because the differences from the actual values are small. However, Figure 12, on the contrary, suggests significant differences.   I also had trouble verifying the described results with the values in the graphs and tables. I recommend making the presentation of the results clearer. In the discussion, please provide an analogy between the results according to reference 10 and the results in works 27-29.

Answer: Thank you for your comments. We have taken everything into account and made changes: we have coordinated the ways of referring to figures, tables, and equations, and made changes to the text. All values have been put in italics. The units of measurement in Table 3 were corrected. Spaces between the number and the unit of measurement have been added to the text. Figure 2 has been corrected. Figures 12 and 13 make it possible to compare the predicted and experimental data; the standard error calculated for equation 8 and equation 9 is 0.00768 and 0.00605, respectively. The other statistical estimates of the above equations indicate their adequacy.

Reviewer 4 Report

Comments and Suggestions for Authors

1. The abstract should be improved by providing the selling points of this research.

2. The authors should provide a table containing a comparative study in the last few years on this topic.

3. Please remove references before 2014 and insert the most recent articles as references. 

 

Comments on the Quality of English Language

N/A

Author Response

1. The abstract should be improved by providing the selling points of this research.

Answer: Thank you, we have made changes to the text.

2. The authors should provide a table containing a comparative study in the last few years on this topic.

Answer: Thank you for your opinion. Perhaps summarizing the information in a table will make it easier to perceive. In the following publications, we will present the analysis of studies in the form of a table. In this paper, the analysis of the studies is presented in the form of text in the discussion section.

3. Please remove references before 2014 and insert the most recent articles as references. 

Answer: We have taken your comment into account as much as possible and added research for 2023-2024.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript can advance for publication.

Author Response

Thank you for your positive feedback.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors,  

I appreciate the authors' approach to revising the contribution after the review process. The authors addressed almost all of my comments, which contributed to a better understanding of the results and enhanced its professionalism. However, I would like to point out one shortcoming to the authors, which is Figure 2. I request the authors to adjust this figure in a way that it does not give the impression of being off the horizontal axis.

Author Response

Thank you for your positive feedback. According to your recommendations, the picture has been corrected.