Effect of Replacing Coke with Biomass Fuel on Sinter Properties and Pollutant Emissions
Round 1
Reviewer 1 Report
The manuscript presents a characterization of a metal sintering process and fits the scope of the journal. The research question is clear and addressed in a set of experimental studies. I find that some revision of the manuscript is required for it to be acceptable for publication. Comments and questions are given below.
Table 1. Explain what the LOI column represents.
Figure 1. Extend the caption to explain what panels a-d show.
In section 3.1 the text refers to “sintering technical indexes”. Is this an established terminology in the field? Otherwise “sintering properties” might be a better term.
Table 4. Please define temperatures T10% and T40%, indices RDI-0.5, RDI+3.15 and RI to help non-specialist readers.
Figure 5. The color bar cannot be read. What does it show? Improve the scale bar so that the size of the images is better indicated. The text discussing Figure 5 can also be revised a bit to help the reader. Line 179 says “the quantity is small”, which quantity? Please clarify what “the local high temperature in the sintering mixture is caused” refers to? Do you mean that the local high temperature causes the size distribution of the pores? An indicative number of the pore diameter would be helpful.
Line 197 refers to the “improvement of sinter reducibility and sinter strength”. I guess this refers to the results presented in section 3.1 & 3.2. Please refer to these previous results in the text.
Line 205. The “Laika phase microscope” should probably be a Leica phase-contrast microscope?
Figure 6. Improve the scale bar so that the size of the images is better indicated. Guide the reader in the text (line 213) by explaining how the calcium ferrate minerals are seen in the image(s).
The results section does not cite any other works in the field. Are there no other studies to be compared with in the discussion of the results?
Language corrections
Line 67 Figs. 3(a) and (c) -> Figs. 1(a) and (c)
Line 80 0.036.1% -> 0.0361%
Line 101 was -> were
Line 102 of sinter -> of the sinter
Line 109 that the content -> that when the content
Line 119 results were shown in Tabs. 4. -> results are shown in Tab. 4.
Line 126 for sinter -> for the sinter
Line 147 properties of sinter -> properties of the sinter
Line 152 pore structure of sinter -> pore structure of the sinter
Line 154 The experimental results -> The results
Line 176 slices of sinter -> slices of the sinter
Line 177 photos of sinter -> photos of the sinter
Line 190 mixing of sintered raw materials -> mixing of sinter raw materials
Line 212 picture of sinter -> picture of a sinter
Line 214 bonded phase for sinter -> bonded phase for the sinter
Line 217 which is the same as -> which is similar to that of
Line 221 low temperature -> low-temperature
Line 221 replaces 40% coke breeze -> replaces 40% of the coke breeze
Line 223 over-melting of sinter -> over-melting of the sinter
Line 233 ant -> and
Line 240 the material layer has not yet formed a wet layer -> the material has not yet formed a wet layer
Line 241 the flux in the material layer does not have time to absorb all the SO2 -> the flux is too high for the material layer to absorb all the SO2
Line 242 so part of the SO2 can enter the flue gas -> so part of the SO2 is emitted
Line 244 will be absorbed by flux -> will be absorbed by flux through the sinter
Line 251 and accelerating the release of SO2 -> and release of SO2
Author Response
Dear Editors and Reviewers:
On behalf of my co-authors, we thank you very much for giving us an opportunity to revise our manuscript, we appreciate editor and reviewers very much for your positive and constructive comments and suggestions on our manuscript entitled “Effect of Replacing Coke with Biomass Fuel on Sinter Properties and Pollutant Emissions”. We have studied comments carefully and have made correction which we hope meet with approval. Revised portion are marked in red in the paper. The main corrections in the paper and the responds to the reviewer’s comments are as follows:
Question: Table 1. Explain what the LOI column represents.
Response: According to reviewer advice, the content of LOI column is added in Table 1, and the text is marked in red.
Question: Figure 1. Extend the caption to explain what panels a-d show.
Response: According to reviewer advice, the paper has extended the caption to explain the meaning of panels a-d which is marked in red.
Question: In section 3.1 the text refers to “sintering technical indexes”. Is this an established terminology in the field? Otherwise “sintering properties” might be a better term.
Response: Sintering technical indexes include vertical sintering rate, drum strength and yield, and sinter metallurgical properties include load softening properties, low temperature breakdown properties, so we chose the different terms.
Question: Table 4. Please define temperatures T10% and T40%, indices RDI-0.5, RDI+3.15 and RI to help non-specialist readers.
Response: According to reviewer advice, we have added the following content, “the load softening properties (T10% is soft melting begins temperature, T40% is soft melting end temperature, and â–³T is the difference between T10% and T40%), low temperature breakdown properties (RDI-0.5 is the wear index, RDI+3.15 is reduced pollination index), and reduction properties (RI) of different sinters were tested”, and the text is marked in red font.
Question: Figure 5. The color bar cannot be read. What does it show? Improve the scale bar so that the size of the images is better indicated. The text discussing Figure 5 can also be revised a bit to help the reader.
Response: According to reviewer advice, we have improved the color bar and scale bar in Figure 5 and have revised the text which are marked in red.
Question: Line 179 says “the quantity is small”, which quantity? Please clarify what “the local high temperature in the sintering mixture is caused” refers to? Do you mean that the local high temperature causes the size distribution of the pores? An indicative number of the pore diameter would be helpful.
Response: we have modified “the quantity is small” to “the volume is small”, and an indicative number of the pore diameter have been added in the paper.
Question: Line 197 refers to the “improvement of sinter reducibility and sinter strength”. I guess this refers to the results presented in section 3.1 & 3.2. Please refer to these previous results in the text.
Response: According to reviewer advice, we have added the notes of results in section 3.1 & 3.2, and the text is marked in red font.
Question: Line 205. The “Laika phase microscope” should probably be a Leica phase-contrast microscope?
Response: According to reviewer advice, we have modified “Laika phase microscope” to “Leica phase-contrast microscope”.
Question: Figure 6. Improve the scale bar so that the size of the images is better indicated. Guide the reader in the text (line 213) by explaining how the calcium ferrate minerals are seen in the image(s).
Response: According to reviewer advice, we have improved the scale bar of the Figure 6, and the calcium ferrate minerals have been marked in the Figure 6.
Question: The results section does not cite any other works in the field. Are there no other studies to be compared with in the discussion of the results?
Response: According to reviewer advice, we have added the relevant studies, and the text is marked in red font.
Question: Language corrections
Line 67 Figs. 3(a) and (c) -> Figs. 1(a) and (c)
Line 80 0.036.1% -> 0.0361%
Line 101 was -> were
Line 102 of sinter -> of the sinter
Line 109 that the content -> that when the content
Line 119 results were shown in Tabs. 4. -> results are shown in Tab. 4.
Line 126 for sinter -> for the sinter
Line 147 properties of sinter -> properties of the sinter
Line 152 pore structure of sinter -> pore structure of the sinter
Line 154 The experimental results -> The results
Line 176 slices of sinter -> slices of the sinter
Line 177 photos of sinter -> photos of the sinter
Line 190 mixing of sintered raw materials -> mixing of sinter raw materials
Line 212 picture of sinter -> picture of a sinter
Line 214 bonded phase for sinter -> bonded phase for the sinter
Line 217 which is the same as -> which is similar to that of
Line 221 low temperature -> low-temperature
Line 221 replaces 40% coke breeze -> replaces 40% of the coke breeze
Line 223 over-melting of sinter -> over-melting of the sinter
Line 233 ant -> and
Line 240 the material layer has not yet formed a wet layer -> the material has not yet formed a wet layer
Line 241 the flux in the material layer does not have time to absorb all the SO2 -> the flux is too high for the material layer to absorb all the SO2
Line 242 so part of the SO2 can enter the flue gas -> so part of the SO2 is emitted
Line 244 will be absorbed by flux -> will be absorbed by flux through the sinter
Line 251 and accelerating the release of SO2 -> and release of SO2
Response: According to reviewer advice, we have made the language corrections, and the text is marked in red font.
We appreciate for Editors/Reviewers’ warm work earnestly, and hope that the correction will meet with approval. Once again, thank you very much for your comments and suggestions.
Yours sincerely,
LIU Chao
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Paper addresses important topic. However, numerous drawbacks are noted:
Table 1 – comprehensive chemical analysis of both solid fuels is required (ash and combustible part) as well as calorific values.
The data about nitrogen in iron ore shall be double-checked versus literature. Overall the value is negligible as compared to the amount of N2 in air.
Line 79 and further – why “powder”?
Line 81 - 0.036.1% ?
Table 2 and overall experiment planning: it would be logical to keep constant not total mass of solid fuels but a calorific value of the mix, otherwise comparable sinter quality cannot be ensured.
Having in mind further discussion, a percentage of charcoal in the mix shall be added to Table 2
Line 99 – what is “v|tome|x s” ?
Line 100 – not “sinter ores” but sinters; and not “from”
Table 4 – indices shall be explained for a multidisciplinary audience
Line 125 – what is “softener”?
Paragraph starting from line 121 fails to provide a relevant explanation: softening properties depend upon gangue composition (affected by biomass adding) and reducibility (correlated with porosity) and have to be discussed accordingly. More reducible sinter shall have higher softening temperature because of lower FeO content and this seems to be not fully in accordance with RI.
Data on sinters’ chemical composition is lacking and shall be provided.
Line 142 – perhaps ferrite, not ferrate
Explanation from Line 130 to 146 is rather vague – presence of any extrema is doubtful here. Difference for both RDIs in #1 and 2 is rather small (might be within the measurement error). So the conclusion - Line 147 and so on - is also vague.
Line 150 “sinter ore” – see above
Section 3.3: There are image analysis techniques (e.g. ImageJ) able to quantify porosity data from the images, including 3D. It is recommended to use them in order obtain and discuss a quantitative information (not for a single cross-section but in a 3D image rendered by CT).
Line 205: Laika > Leica
Fig 5 - dimension shall be indicated
Fig 6 – phases shall be indicated
Section 3.5 - NOx emissions are greatly determined by temperature level which is not discussed. And air is abundant source of Nitrogen, so N content in the fuel might not be essential.
There are very numerous studies on iron ore sintering using biomass; however, Section 3 has no references at all. This is not acceptable for an academic paper. The results shall be discussed versus data obtained by other researchers.
Paper shall be revised completely for language.
Author Response
Dear Editors and Reviewers:
On behalf of my co-authors, we thank you very much for giving us an opportunity to revise our manuscript, we appreciate editor and reviewers very much for your positive and constructive comments and suggestions on our manuscript entitled “Effect of Replacing Coke with Biomass Fuel on Sinter Properties and Pollutant Emissions”. We have studied comments carefully and have made correction which we hope meet with approval. Revised portion are marked in red in the paper. The main corrections in the paper and the responds to the reviewer’s comments are as follows:
Question: Table 1–comprehensive chemical analysis of both solid fuels is required (ash and combustible part) as well as calorific values.
Answer: According to reviewer advice, we have added comprehensive chemical analysis of both solid fuels in Table 2, and the text is marked in red font.
Question: The data about nitrogen in iron ore shall be double-checked versus literature. Overall the value is negligible as compared to the amount of N2 in air.
Answer: According to reviewer advice, the data about nitrogen in iron ore has been double-checked versus literature. N in iron ore can generate fuel type NOx, while N2 in air is basically thermal type NOx, which can not generate NOx under sintering conditions, so N2 in air is not considered.
Question: Line 79 and further – why “powder”?
Answer: The raw material of iron ore sintering is powder, the purpose of sintering is to prepare powder to form a block, which is to meet the requirements of blast furnace smelting.
Question: Line 81 - 0.036.1% ?
Answer: According to reviewer advice, we have modified it.
Question: Table 2 and overall experiment planning: it would be logical to keep constant not total mass of solid fuels but a calorific value of the mix, otherwise comparable sinter quality cannot be ensured.
Answer: According to reviewer advice, we have added the following content “Due to the calorific values of both solid fuels is relatively similar, the experimental scheme of the sintering cup keep constant total mass of solid fuels in the mix, which is presented in Table 3”. we have found the issue, and will be more rigorous in the future.
Question: Having in mind further discussion, a percentage of charcoal in the mix shall be added to Table 2
Answer: According to reviewer advice, we have added a percentage of charcoal in the mix to theTable 2.
Question: Line 99 – what is “v|tome|x s”?
Answer: For the readers to understand, we have modified “v|tome|x s” to “X-Ray Computed Tomography”.
Question: Line 100 – not “sinter ores” but sinters; and not “from”
Answer: According to reviewer advice, we have modified “sinter ores” to “sinters” in the paper.
Question: Table 4 – indices shall be explained for a multidisciplinary audience
Answer: According to reviewer advice, we have added the following content, “the load softening properties (T10% is soft melting begins temperature, T40% is soft melting end temperature, and â–³T is the difference between T10% and T40%), low temperature breakdown properties (RDI-0.5 is the wear index, RDI+3.15 is reduced pollination index), and reduction properties (RI) of different sinters were tested”, and the text is marked in red font.
Question: Line 125 – what is “softener”?
Answer: According to reviewer advice, we have modified “With the development of the increase of biomass charcoal”, and have deleted “softener”.
Question: Paragraph starting from line 121 fails to provide a relevant explanation: softening properties depend upon gangue composition (affected by biomass adding) and reducibility (correlated with porosity) and have to be discussed accordingly. More reducible sinter shall have higher softening temperature because of lower FeO content and this seems to be not fully in accordance with RI.
Answer: According to reviewer advice, we found our mistake of RI, the RI is 83.45 not 73.45 when the content of biomass charcoal is 60%. We have modified it and added relevant explanation.
Question:Data on sinters’ chemical composition is lacking and shall be provided.
Answer: According to reviewer advice, we have provided the sinters’ chemical composition in Table 4.
Question: Line 142 – perhaps ferrite, not ferrate.
Answer: According to reviewer advice, we have modified “ferrate” to “ferrite” in the paper.
Question: Explanation from Line 130 to 146 is rather vague – presence of any extrema is doubtful here. Difference for both RDIs in #1 and 2 is rather small (might be within the measurement error). So the conclusion - Line 147 and so on - is also vague.
Answer: According to reviewer advice, we have added the explanation of the relevant experimental results, linked them to Section 3.3 and 3.4.
Question: Line 150 “sinter ore” – see above
Answer: According to reviewer advice, we have modified “sinter ore” to “sinter” in the paper.
Question: Section 3.3: There are image analysis techniques (e.g. ImageJ) able to quantify porosity data from the images, including 3D. It is recommended to use them in order obtain and discuss a quantitative information (not for a single cross-section but in a 3D image rendered by CT).
Answer: According to reviewer advice, we will learn the relevant image analysis software to make up for the lack of data processing, thank you for your guidance.
Question: Line 205: Laika > Leica
Answer: According to reviewer advice, we have modified “Laika” to “Leica”.
Question: Fig 5-dimension shall be indicated
Answer: According to reviewer advice, we have improved dimension of the color bar and scale bar in Figure 5.
Question: Fig 6-phases shall be indicated
Answer: According to reviewer advice, we have improved the scale bar of the Figure 6, and the calcium ferrate minerals have been marked in the Figure 6.
Question: Section 3.5 - NOx emissions are greatly determined by temperature level which is not discussed. And air is abundant source of Nitrogen, so N content in the fuel might not be essential.
Answer: N in iron ore can generate fuel type NOx, while N2 in air is basically thermal type NOx, which can not generate NOx under sintering conditions, so N2 in air is not considered.
Question: There are very numerous studies on iron ore sintering using biomass; however, Section 3 has no references at all. This is not acceptable for an academic paper. The results shall be discussed versus data obtained by other researchers.
Answer: According to reviewer advice, we have added the relevant studies, and the text is marked in red font.
Question: Paper shall be revised completely for language.
Answer: According to reviewer advice, we have revised language completely.
We appreciate for Editors/Reviewers’ warm work earnestly, and hope that the correction will meet with approval. Once again, thank you very much for your comments and suggestions.
Yours sincerely,
LIU Chao
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Authors improved the paper. However, few remarks are noted.
General comments/recommendations:
Raw materials used in sintering are only partially powder but, predominantly, they are in a coarse fraction. By powder usually a fraction below 1 mm is meant. So authors didn’t understand the question.
Paragraph starting Line 141 still gives rather vague explanation. Why proportion of charcoal makes change? Different fuel reactivity (very essential issue to be considered but not discussed, except brief mentioning in Introduction)? Different specific density is also important, though it is discussed not here but in the next section. It is advisable to discuss (including references to other studies) and present the authors’ vision of why and how proportion of charcoal may affect different aspects of sintering process (e.g. why temperature in the sintering zone may change, though calorific values of fuels are almost the same and so on) in a dedicated paragraph.
Terminology issues:
- Term “law” is treated inappropriately - Line 122, Line 262.
- Line 127: “soft melting begins temperature” => start softening temperature
- Line 127: “soft melting end temperature” => temperature of 40% shrinkage corresponding to end of softening.
- Explanation of RDIs and RI is irrelevant and shall be revised towards the terminology used in corresponding standards – e.g. RDI is a reduction degradation index (not “wear index”) and so on. “Pollination” ?
Paper still has numerous language (grammar and style) drawbacks:
- Title of table 2
- Subtitles of Fig 1
- Mowasture ?
- Line 136 “With the development of the increase” => “With the increase”
- and so on
Author Response
Question：Raw materials used in sintering are only partially powder but, predominantly, they are in a coarse fraction. By powder usually a fraction below 1 mm is meant. So authors didn’t understand the question.
Response: According to reviewer advice, we have revisited this issue and decided to remove the "powder".
Question：Paragraph starting Line 141 still gives rather vague explanation. Why proportion of charcoal makes change? Different fuel reactivity (very essential issue to be considered but not discussed, except brief mentioning in Introduction)? Different specific density is also important, though it is discussed not here but in the next section. It is advisable to discuss (including references to other studies) and present the authors’ vision of why and how proportion of charcoal may affect different aspects of sintering process (e.g. why temperature in the sintering zone may change, though calorific values of fuels are almost the same and so on) in a dedicated paragraph.
Response: According to reviewer advice, we have added the relevant descriptions and referred to other studies, which is marked in red font.
Question：Term “law” is treated inappropriately - Line 122, Line 262.
Response: According to reviewer advice, we have corrected them, which is marked in red font.
Question：Line 127: “soft melting begins temperature” => start softening temperature
Response: According to reviewer advice, we have corrected it, which is marked in red font.
Question：Line 127: “soft melting end temperature” => temperature of 40% shrinkage corresponding to end of softening.
Response: According to reviewer advice, we have corrected it, which is marked in red font.
Question：Explanation of RDIs and RI is irrelevant and shall be revised towards the terminology used in corresponding standards – e.g. RDI is a reduction degradation index (not “wear index”) and so on. “Pollination” ?
Response: According to reviewer advice, we have corrected the explanation of RDIs and RI, which is marked in red font.
Question：Paper still has numerous language (grammar and style) drawbacks:
Title of table 2
Subtitles of Fig 1
Mowasture ?
Line 136 “With the development of the increase” => “With the increase”
and so on
Response: According to reviewer advice, we have made the language corrections, and the text is marked in red font.
Author Response File: Author Response.pdf
