Study of the Physical Behaviour and the Carbothermal Reduction of Self-Reducing Briquettes Developed with Iron Ore Fines, Charcoal and Silica Fume Residues

Round 1

Reviewer 1 Report

1.      Abstract is not properly presented.

2.      Introduction should be more informative, so please concern about the more appropriate citations which are related to your paper.

3.      Sentence patterns are not clear enough and front should be same in whole paper.

4.      In the introduction part mainly focus on the FeSi production, process and others. But, lots of gap based on the tittle of this work. Should be improved that part?

5.      Why use FeSi75%? Any major function of this.

6.      Why used the binder proportion 2.5,5,7.5 and 10%? Is there specification of that proportion for using?

7.      Mix design is not clear? Could be more specific and clear?

8.      What is the main function of the Shatter test?

9.      Phase diagram really interesting of this research. However, I don’t understand the function of this. Could you describe.

10.   Conclusion should be written more specifically.

Comments for author File: Comments.pdf

Author Response

Dear reviewer,

Thank you very much for your important willingness to correct our work and promote the realization of a consolidated scientific article. 
I have made changes to the text in response to your suggestions and considerations and hope to have made the text more suitable for publication.
Markings have also been made in the attached text to confirm the implementation of your suggestions.

I emphasize that as suggested, we send the text for English language correction.

Responses to your comments are given below:

 

1.  Abstract is not properly presented. Changes were made to the abstract
2.  Introduction should be more informative, so please concern about the more appropriate citations which are related to your paper. The introduction has been changed and adapted more appropriate citations.
3. Sentence patterns are not clear enough and front should be same in whole paper. Corrections were made throughout the text for clarity of content and also English language verification at a company in Norway.
4. In the introduction part mainly focus on the FeSi production, process and others. But, lots of gap based on the tittle of this work. Should be improved that part? The introduction part was improved, seeking to correlate the production, process, waste generation, waste agglomeration (briquetting), and the need to study the behavior (physical and metallurgical) of these self-reducing briquettes for possible insertion in submerged arc furnaces.
5. Why use FeSi75%? Any major function of this. Only because waste from this segment of FeSi75 was used, this metallurgical company donated the samples studied.
6. Why used the binder proportion 2.5,5,7.5 and 10%? Is there specification of that proportion for using? In preparing the self-reducing briquettes, mixtures were developed using three types of binders: Portland cement, hydrated lime, sodium silicate. In addition to mixtures without the addition of binder. The addition of binder was considered necessary, so the addition was initially performed with variations that occurred in the proportions of 0.00%; 2.50%; 5.00%; 7.50% and 10.00% based on studies related to the works [18, 19, 46-48, 66]. 
7. Mix design is not clear? Could be more specific and clear? The formulation of the self-reducing briquettes was performed by the stoichiometric calculations of the simplified mass balance to produce 1 ton of FeSi75. Indeed, to know the amount of raw materials needed to produce 1 ton of FeSi75, it is necessary to know the chemical composition of the raw materials and the alloy to be produced. In this perspective, as described [6,13-14] to produce FeSi alloys, the control of the mixtures must be performed quantitatively (amount of carbon introduced in the carbon/quartz) and qualitatively (quartz nature, reactivity, particle size distribution of the raw material and porosity of the charge). 
   The production of self-reducing briquettes in this work aims to use a high fraction of silica in the briquette mixture, increasing its reactivity, reducing waste in the production process. On the other hand, the silica fume will replace quartz and this was the raw material that provided SiO₂ for the self-reducing briquettes.  Therefore, the percentage composition of the waste to produce self-reducing briquettes is described in Table 1.

 

8. What is the main function of the Shatter test? Calculate the drop degradation, relating the drop of the raw material from the height of the conveyor belt to the introduction surface in the SAF's.
9. Phase diagram really interesting of this research. However, I don’t understand the function of this. Could you describe. Using the results of the mass or atomic composition of Si, FeSi and FeSi₂ phases (obtained by SEM/EDS analysis), it is possible to demonstrate, using the FeSi phase diagram, the presence of FeSi75 and FeSi50 of the metal. Therefore, in this work, most of the analyzed metals are about 50/50 with the FeSi₂, i.e., the FeSi75 and some metal pearls are in the area of the FeSi-FeSi₂ diagram, over the FeSi50.
10. Conclusion should be written more specifically. The conclusion was rewritten and improved.

11) Why used that? Why not MIP or MicroCT. Unfortunately, we lacked the funding to do the porosity testing on MIP or MicroCT equipment.

 

Author Response File: Author Response.pdf

Reviewer 2 Report

A agglomeration in the form of self-reducing briquettes with waste from the FeSi 75% industry was proposed in this manuscript. Many experiments have been carried out to analyze the performance of the agglomeration. The conclusions can contribute positively in relation to the properties presented by the self-reducing briquettes with the respective residues of the FeSi industry segment. Some suggestions are proposed for reference and please answer the following questions.

1.      There is a lack of analysis on the research status of relevant fields in Chapter Introduction, and it is suggested to compensate for relevant contents.

2.      Table 1 shows that a total of 13 samples with different proportions of mixtures were prepared in this study, but the basis for determining the proportion of samples and theoretical support are lacking. It is suggested to supplement relevant contents.

3.      According to the Formula (1) and description, 2000 ° C is the SiO₂ reduction temperature and the maximum temperature of the experimental furnace. Why is the maximum reduction experimental temperature 1800 ° C in Table 2?

4.      Reduction-fusion tests, Scanning electron microscopy (SEM) test and semi-quantitative analyses were carried out in this manuscript, but the significance of these tests was not explained. It is suggested to supplement relevant contents at the beginning of Chapter 2.5.

Author Response

Dear reviewer,

Thank you very much for your important willingness to correct our work and promote the realization of a consolidated scientific article. 
I have made changes to the text in response to your suggestions and considerations and hope to have made the text more suitable for publication.
Markings have also been made in the attached text to confirm the implementation of your suggestions.

I emphasize that as suggested, we send the text for English language correction.

Responses to your comments are given below. 

1. There is a lack of analysis on the research status of relevant fields in Chapter Introduction, and it is suggested to compensate for relevant contents. This information was added to the text of the introduction.
2. Table 1 shows that a total of 13 samples with different proportions of mixtures were prepared in this study, but the basis for determining the proportion of samples and theoretical support are lacking. It is suggested to supplement relevant contents. 

   The formulation of the self-reducing briquettes was performed by the stoichiometric calculations of the simplified mass balance to produce 1 ton of FeSi75. Indeed, to know the amount of raw materials needed to produce 1 ton of FeSi75, it is necessary to know the chemical composition of the raw materials and the alloy to be produced. In this perspective, as described [6,13-14] to produce FeSi alloys, the control of the mixtures must be performed quantitatively (amount of carbon introduced in the carbon/quartz) and qualitatively (quartz nature, reactivity, particle size distribution of the raw material and porosity of the charge). 
   The production of self-reducing briquettes in this work aims to use a high fraction of silica in the briquette mixture, increasing its reactivity, reducing waste in the production process. On the other hand, the silica fume will replace quartz and this was the raw material that provided SiO₂ for the self-reducing briquettes.  Therefore, the percentage composition of the waste to produce self-reducing briquettes is described in Table 1 and 2.

    3.      According to the Formula (1) and description, 2000 ° C is the SiO₂ reduction temperature and the maximum temperature of the experimental furnace. Why is the maximum reduction experimental temperature 1800 ° C in Table 2? According to the works [7,55,57] the melting and reduction onset temperatures for different industrial quartz range from 1600°C to 2000°C. It is noteworthy that a preliminary test was conducted to investigate the behavior of self-heating briquettes in this investigation at the temperature of 2000°C. Thus, a sample of a particular treatment with a mass of 24.65g was selected for performing the reduction experiment at the immediate insertion temperature of 2000°C and held for 30 minutes in this system. The intention was to check how much of the briquette mass would be consumed and thus measure how much of the material would remain. In this way, it could define whether the
   time could be extended or not, establishing the methodology of target temperatures and exposure time for the reduction experiments.
   Thus, after the exploratory test, only 4.50g of the researched treatment sample remained (Figure 4b).  Due to this large mass loss, the test at the target temperature of 2000°C, was performed only for this experimental treatment. experimental treatment. It is notable that due to this occurrence, there is an indication that most of the silicon of silicon left the experimental system as SiO gas. Only the test at the target temperature of 2000°C, only for this experimental treatment.

   4. Reduction-fusion tests, Scanning electron microscopy (SEM) test and semi-quantitative analyses were carried out in this manuscript, but the significance of these tests was not explained. It is suggested to supplement relevant contents at the beginning of Chapter 2.5. As requested, the information was inserted into the work.

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript is well written and well organized but before publication it needs to be improved.

1) The logic of the introduction needs to be strengthened, and the current research progresses and the existing problems were not shown in the introduction.

2) Please pay attention to the difference between article and experimental report. The content of materials and methods is too detailed. Furthermore, section 2.3.1 does not need to be divided separately.

3) The form of table in the manuscript is not unique.

4) Line 455-457, the literature [47] pointed out that the addition of lime as binder has the best performance at 25% - 30%, however, the addition ratio of lime is 2.5% - 10%, in the manuscript. How is the addition determined?

Author Response

Dear reviewer,

Thank you very much for your important willingness to correct our work and promote the realization of a consolidated scientific article. 
I have made changes to the text in response to your suggestions and considerations and hope to have made the text more suitable for publication.
Markings have also been made in the attached text to confirm the implementation of your suggestions.

I emphasize that as suggested, we send the text for English language correction.

Responses to your comments are given below:

1) The logic of the introduction needs to be strengthened, and the current research progresses and the existing problems were not shown in the introduction. Introduction modified and restructured to meet the request.

2) Please pay attention to the difference between article and experimental report. The content of materials and methods is too detailed. Furthermore, section 2.3.1 does not need to be divided separately. A reduction has been made to the content of materials and methods. 

3) The form of table in the manuscript is not unique. The tables' shapes were reorganized and corrected.

4) Line 455-457, the literature [47] pointed out that the addition of lime as binder has the best performance at 25% - 30%, however, the addition ratio of lime is 2.5% - 10%, in the manuscript. How is the addition determined? In preparing the self-reducing briquettes, mixtures were developed using three types of binders: Portland cement, hydrated lime, sodium silicate and to mixtures without the addition of binder.without the addition of binder. The addition of binder was considered necessary, so the addition was initially performed with variations that occurred in the proportions of 0.00%; 2.50%; 5.00%; 7.50% and 10.00% based on studies related to the works [19-20, 46-48, 66]. Previous research [47] produced briquettes from coal fines and different types of or-ganic, inorganic, and combined binders, the following basic mixture (% dry matter) was assumed: coal fines-90, bio-mass-6 and binder-4. Thus, when using virgin lime or hy-drated lime, the briquettes prepared with this type of binder did not show satisfactory re-sults, causing deterioration both in compaction and later showing mechanical strength well below the assumed minimum (R= 85%). Regarding the study of [67] when investi-gating lignite agglomeration, they found that the cohesive properties of lime are not strong for some types of materials and that the proportion of lime should be between 25% - 30% when used as a single binder.

Gently, see line 462-477

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Could you make it more visible the figures in that paper? 

Author Response

Dear Reviewer,

I have made changes to the text in response to your suggestions and considerations and hope I have made the text more suitable for publication. I thank you for your excellent contribution in making this work relevant.
Thus, what was directed to be improved, I have readily complied with:
1- Are all cited references relevant to the research
I have therefore made changes to add and remove some references that might be considered unnecessary.
2- Are the arguments and discussion of findings coherent, balanced and compelling? I made improvements and changes to the text regarding the results and discussion. 
3- For empirical research, are the results clearly presented? I made adjustments to improve the whole presentation of the results, correcting the numbers and trying to make the text more coherent.
4- Is the article properly referenced? To make the references more appropriate, I reviewed all the references and tried to improve their coherence with the text.

Could you make it more visible the figures in that paper? 
I have re-edited the figures and made adjustments to make the numbers and information more visible.

I also point out that the text of the article was sent to an English proofreading company.

Reviewer 3 Report

I think the revised manuscript is recommended to be published.

Author Response

Dear reviewer,

The text has been revised with correction of the English language in response to your recommendation and I hope I have made the text most suitable for publication. I thank you for your excellent contribution in making this work relevant.