An Innovative Technique for Comprehensive Utilization of High Aluminum Iron Ore via Pre-Reduced-Smelting Separation-Alkaline Leaching Process: Part I: Pre-Reduced-Smelting Separation to Recover Iron
Round 1
Reviewer 1 Report
General impressions to the authors:
If I compare this manuscript and its achievements with the present blast furnace performance, the iron recoveries reported are at the best modest. Today, 100 % of the blast furnace slag produced in Europe is used for cement manufacturing without extra treatment steps. Additionally, carbon consumption in this novel flow sheet is more than 3x the blast furnace route. Typically, less than 500 kg coke per ton of hot metal is used (C/Fe < 0.5) in the blast furnace for maintaining the process temperature and reducing iron oxides to hot metal, compared with the proposed case of 1500 kg/tn HM (or C/Fe = 1.5, excluding the carbon added in the phase separation)! These facts and the huge carbon footprint involved does not justify calling this proposed concept and its very complicated flow sheet ‘green’.
Comments and needs for modifications:
(1) As the aim of the development work was an improvement in the processing technology by a novel flow-sheet, the Introduction Chapter must present a description or short review of the state-of-the art in the field, which in this case is the smelting reduction of iron oxides. It will give a strong basis for the evaluation of the present observations.
(2) The authors are using unnecessary abbreviations (like e.g. ‘HAIO’) which make the message of this manuscript difficult to read and understand.
(3) In general, the English needs upgrading by a native speaker. There are also a number of spelling errors in the manuscript which indicates that the authors have not utilized the word processor’s checker feature before submitting it.
(4) On p. 2, rows 73-78, the tables giving the total assay and mineralogical compositions do not match. The concentrations of ore components after LOI are larger that the numbers given in Table 1 and, therefore, in the minerals distribution Tables 2 and 3 total Fe and Al2O3 cannot be the same as in Table 1.
(5) Table 4 gives measured elemental compositions of the phases in the ore. The values have been reported with an extremely and unexceptionally high precision of two decimals, but no information was presented on the validated accuracies of the analytical techniques used for the raw materials. The same is valid with the various results given later in the manuscript, such as yields and grades. Besides, the analytical tools used for the products were presented in Ch 2.3 without any details of the external standards used and the accuracies/uncertainties obtained in the actual measurements.
(6) On p. 4 and 7, rows 84 and 178, respectively, the variable ‘binary basicity’ is used without defining it.
(7) In the experimental methods, all the details concerning every equipment and their process parameters used must be included in Ch 2.2 and its sub-chapters. In the present form of the manuscript, the information given about the analytical methods and procedures is totally insufficient for any third person to repeat the experiments and verify the analytical results.
(8) How the concentration of metallic iron (Eq. (1) and rows 113-114) was determined on p. 5?
(9) On page 6, rows 130-131, the L/S ratio of 300 rpm is mentioned. What is that?
(10) On p. 6, rows 148-152, in Eq. (4) a variable k1 is mentioned as ‘the reference intensity’. That very factor must be defined in more detail in text.
(11) The ash analysis of the used soft coal has a total of about 70 % (Table 5). What is the rest?
(12) Figures 4-6 use the expression ‘Iron grade’ as ordinate axis. It is of interest to know what the authors mean by these iron assay values between 38 and 40 % in a solid-state reduction experiment producing metallic iron as the product? What is the rest in the metal phase, e.g. in Table 8?
(13) On p. 9, rows 209-216, complex chemical reactions have been presented for explaining the chemical processes occurring in the pre-reduction and phase separation (melting) steps. The evaluation on the direction of reaction is carried out based on the Gibbs energy change only, in spite of the fact that reactions (7) - (8) and (11) - (12) contain gaseous reactants on both sides of the equation. Then, the direction will be defined by the ratio of CO2-to-CO in the system and not by the standard Gibbs energy change alone.
(14) The viscosity data on p. 9-10 has a typing error in the unit used.
(15) On p. 10, figure 8, the authors use the phrase ‘quantity of liquid’ probably meaning the mass or amount fraction?
(16) On p. 10, row 234 and later, the authors launch a new variable ‘the smelting separation index’ without defining it.
(17) The authors added coke up to 20 wt% of the charge (C/Fe ≈ 0.6) in the melting separation of the pre-reduced material. Did you remove the excess carbon from the pre-reduced product prior to melting and what was the reason for adding such a massive amount of reductant in the phase separation step? The reasons for selecting the processing conditions in each step should be clarified in the Materials and methods Chapter.
(18) Figure 14 and its EDS spectra contain very little information but taking almost a full page, and the EDS spectra can be condensed to a short table without jeopardizing the message.
(19) The roasting conditions on p. 14 must be relocated in the manuscript and specified in detail in the Materials and methods Chapter, including the possible pre-treatments made with the raw materials.
(20) On p. 14, the figure caption should be essentially self-explaining and give all the necessary data required to understand the results and their boundary conditions.
(21) Before any conclusions can be drawn from the results, Ch 3 must include an analysis of the present e.g. energy, additive and reductant consumption data of the new method compared with the available technologies of today, such as the blast furnace. Only a full comparison of the obtained results with state-of-the art allows you to make the conclusions in Ch 4.
(22) On p. 14 and later, the phrase ‘flow scheme’ may refer to the more conventional phrase ‘flow sheet’?
Comments for author File: 
Comments.pdf
Author Response
Comments and needs for modifications:
(1) As the aim of the development work was an improvement in the processing technology by a novel flow-sheet, the Introduction Chapter must present a description or short review of the state-of-the art in the field, which in this case is the smelting reduction of iron oxides. It will give a strong basis for the evaluation of the present observations.
Author’s response: The description of the state-of-the art in the field has been presented in the Introduction Chapter.
(2) The authors are using unnecessary abbreviations (like e.g. ‘HAIO’) which make the message of this manuscript difficult to read and understand.
Author’s response: The HAIO is the abbreviation of high aluminum iron ore and the author has been modified in this paper.
(3) In general, the English needs upgrading by a native speaker. There are also a number of spelling errors in the manuscript which indicates that the authors have not utilized the word processor’s checker feature before submitting it.
Author’s response: Thanks for your valuable comments, and we did our best to modified the manuscript as seen the revised paper.
(4) On p. 2, rows 73-78, the tables giving the total assay and mineralogical compositions do not match. The concentrations of ore components after LOI are larger that the numbers given in Table 1 and, therefore, in the minerals distribution Tables 2 and 3 total Fe and Al2O3 cannot be the same as in Table 1.
Author’s response: The author re-measured by chemical titration based on the handbook of chemical phase analysis of ores and industrial products. The results have been modified in this paper.
(5) Table 4 gives measured elemental compositions of the phases in the ore. The values have been reported with an extremely and unexceptionally high precision of two decimals, but no information was presented on the validated accuracies of the analytical techniques used for the raw materials. The same is valid with the various results given later in the manuscript, such as yields and grades. Besides, the analytical tools used for the products were presented in Ch 2.3 without any details of the external standards used and the accuracies/uncertainties obtained in the actual measurements.
Author’s response: In order to ensure the accuracy of the data, all data in this article are taken as two significant values after the decimal point.
(6) On p. 4 and 7, rows 84 and 178, respectively, the variable ‘binary basicity’ is used without defining it.
Author’s response: The binary basicity is the ratio of w(CaO) to w(SiO2) (w(CaO)/w(SiO2)) and the author has been modified in this paper.
(7) In the experimental methods, all the details concerning every equipment and their process parameters used must be included in Ch 2.2 and its sub-chapters. In the present form of the manuscript, the information given about the analytical methods and procedures is totally insufficient for any third person to repeat the experiments and verify the analytical results.
Author’s response: All the details concerning every equipment and their process parameters have been presented in the paper.
(8) How the concentration of metallic iron (Eq. (1) and rows 113-114) was determined on p. 5? Author’s response: The concentration of metallic iron was determined by chemical titration based on the national standards (GB/T 6730.63).
(9) On page 6, rows 130-131, the L/S ratio of 300 rpm is mentioned. What is that?
Author’s response: The L/S ratio of 10 ml/g means the liquid-to-solid mass ratio is 10 ml/g; and the 300 rpm means the mechanical stirring speed is 300 r/min
(10) On p. 6, rows 148-152, in Eq. (4) a variable k1 is mentioned as ‘the reference intensity’. That very factor must be defined in more detail in text.
Author’s response: The reference intensity is namely diffraction peak intensity and the author has been explained in this paper.
(11) The ash analysis of the used soft coal has a total of about 70 % (Table 5). What is the rest?
Author’s response: The rest is the loss on ignition (LOI).
(12) Figures 4-6 use the expression ‘Iron grade’ as ordinate axis. It is of interest to know what the authors mean by these iron assay values between 38 and 40 % in a solid-state reduction experiment producing metallic iron as the product? What is the rest in the metal phase, e.g. in Table 8?
Author’s response: The iron grade refers to the content of total iron in the pre-reduced pellets, which including metallic iron content and “FeO” content. The rest substance in the pre-reduced pellets is gangue, and the content of these minerals is shown in the Table 6.
(13) On p. 9, rows 209-216, complex chemical reactions have been presented for explaining the chemical processes occurring in the pre-reduction and phase separation (melting) steps. The evaluation on the direction of reaction is carried out based on the Gibbs energy change only, in spite of the fact that reactions (7) - (8) and (11) - (12) contain gaseous reactants on both sides of the equation. Then, the direction will be defined by the ratio of CO2-to-CO in the system and not by the standard Gibbs energy change alone.
Author’s response: The gas-phase equilibrium of reactions (7)-(8) and (11)-(12) has been presented and explained in the paper.
(14) The viscosity data on p. 9-10 has a typing error in the unit used.
Author’s response: The unit of viscosity data has been modified.
(15) On p. 10, figure 8, the authors use the phrase ‘quantity of liquid’ probably meaning the mass or amount fraction?
Author’s response: The quantity of liquid means the mass or amount fraction of liquid phase.
(16) On p. 10, row 234 and later, the authors launch a new variable ‘the smelting separation index’ without defining it.
Author’s response: The smelting separation index includes the content of total iron in the pig iron and the recovery of iron.
(17) The authors added coke up to 20 wt% of the charge (C/Fe ≈ 0.6) in the melting separation of the pre-reduced material. Did you remove the excess carbon from the pre-reduced product prior to melting and what was the reason for adding such a massive amount of reductant in the phase separation step? The reasons for selecting the processing conditions in each step should be clarified in the Materials and methods Chapter.
Author’s response: The author removed the excess carbon from the pre-reduced product prior to melting. The reason for adding such a massive amount of reductant in the phase separation step is the low metallization rate of pre-reduced pellets. The reasons for selecting the processing conditions in each step has been clarified in the Materials and Methods Chapter.
(18) Figure 14 and its EDS spectra contain very little information but taking almost a full page, and the EDS spectra can be condensed to a short table without jeopardizing the message.
Author’s response: The EDS spectra has been condensed to a short table in the paper.
(19) The roasting conditions on p. 14 must be relocated in the manuscript and specified in detail in the Materials and methods Chapter, including the possible pre-treatments made with the raw materials.
Author’s response: The roasting conditions on p.14 are optimal, which determined by experimentally. So, the roasting conditions are uncertain in the Material and Methods Chapter.
(20) On p. 14, the figure caption should be essentially self-explaining and give all the necessary data required to understand the results and their boundary conditions.
Author’s response: The necessary data of the figure caption has been presented in this paper.
(21) Before any conclusions can be drawn from the results, Ch 3 must include an analysis of the present e.g. energy, additive and reductant consumption data of the new method compared with the available technologies of today, such as the blast furnace. Only a full comparison of the obtained results with state-of-the art allows you to make the conclusions in Ch 4.
Author’s response: The analysis of energy, additive and reductant consumption data of the new method has been drawn in the paper.
(22) On p. 14 and later, the phrase ‘flow scheme’ may refer to the more conventional phrase ‘flow sheet’? Author’s response: The flow scheme has been modified to flow sheet in this paper.
Author Response File: Author Response.pdf
Reviewer 2 Report
The Authors presented the possibilities of reducing poor iron ores with a high content of aluminum for the production of pig iron, as well as extraction from slag and leaching of aluminum. The proposed multi-stage process allowed this. At the same time, the residue from the leaching process is a raw material for the cement industry. This is beneficial from the point of view of the ecological use of materials. The use of other types of reducers would make it possible to compare studies conducted in Europe with those of the Authors. Please treat this as a future solution.
Adjustments require:
1) in paragraphs 219-229, 234-239 and Fig. 9b there is - viscosity: Pa·S; it should be Pa·s (second) in SI
2) in verses 21, 297, 308, 314, 336 is mL/g, is to be ml/g in SI
Author Response
Comments and Suggestions for Authors
The Authors presented the possibilities of reducing poor iron ores with a high content of aluminum for the production of pig iron, as well as extraction from slag and leaching of aluminum. The proposed multi-stage process allowed this. At the same time, the residue from the leaching process is a raw material for the cement industry. This is beneficial from the point of view of the ecological use of materials. The use of other types of reducers would make it possible to compare studies conducted in Europe with those of the Authors. Please treat this as a future solution.
Adjustments require:
1) in paragraphs 219-229, 234-239 and Fig. 9b there is - viscosity: Pa·S; it should be Pa·s (second) in SI
Author’s response: The Pa·S has been modified to Pa·s and the author has been modified in this paper.
2) in verses 21, 297, 308, 314, 336 is mL/g, is to be ml/g in SI
Author’s response: The mL/g has been modified to ml/g and the author has been modified in this paper.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
General impressions to the authors:
In the following review, the original replies for v1 have been critically analysed and the places where further attention is required from the authors have been highlighted in yellow. Some new observations were also collected in the end of the original issues of attention.
The key question of this manuscript and its lacking details can be generally condensed as:
The issue of energy consumption and carbon footprint are the core questions of this manuscript. Therefore, the statements related to them must be justified by adequate and strong literature references from the public domain.
Typically, less than 500 kg coke per ton of hot metal (HM) is used (C/Fe < 0.5 or 500 kg/t HM; see, e.g., Bertling: ISIJ Internat., 39 (1999)(7) pp. 617-624) in the blast furnace for maintaining the process temperature and reducing the iron oxides to metal, compared with the proposed case of >1500 kg/t HM (or C/Fe = 1.5, excluding the carbon added in the phase separation)! Carbon consumption in this novel flow sheet is, thus, more than 3x the current blast furnace route, not half as stated in the conclusions. These facts and the involved huge carbon footprint reported do not justify calling this proposed concept and its highly complicated flow sheet ‘green’. Please, address the above issues sufficiently and clearly in the next version of the manuscript.
Specific comments and needs for modifications for v1:
As the aim of the development work was an improvement in the processing technology by a novel flow-sheet, the Introduction Chapter must present a description or short review of the state-of-the art in the field, which in this case is the smelting reduction of iron oxides. It will give a strong basis for the evaluation of the present observations.
OK, even if no citation to the blast furnace technology and its energy consumption was given in the revised Introduction Ch, in spite of the discussion provided on p. 17 (rows 356-357).
The authors are using unnecessary abbreviations (like e.g. ‘HAIO’) which make the message of this manuscript difficult to read and understand.
OK.
In general, the English needs upgrading by a native speaker. There are also a number of spelling errors in the manuscript which indicates that the authors have not utilized the word processor’s checker feature before submitting it.
Please, use the language correction services provided by various publishing houses.
On p. 2, rows 73-78, the tables giving the total assay and mineralogical compositions do not match. The concentrations of ore components after LOI are larger that the numbers given in Table 1 and, therefore, in the minerals distribution Tables 2 and 3 total Fe and Al2O3 cannot be the same as in Table 1.
OK.
Table 4 gives measured elemental compositions of the phases in the ore. The values have been reported with an extremely and unexceptionally high precision of two decimals, but no information was presented on the validated accuracies of the analytical techniques used for the raw materials. The same is valid with the various results given later in the manuscript, such as yields and grades. Besides, the analytical tools used for the products were presented in Ch 2.3 without any details of the external standards used and the accuracies/uncertainties obtained in the actual measurements.
As mentioned in the review report of v1 above, two decimal digits is a very high accuracy for materials’ compositions and chemical analyses. Reporting so accurate concentrations and e.g. yields requires detailed descriptions of the calibration procedures made in the analytical methods and equipment, before the values can be presented in a scientific publication.
On p. 4 and 7, rows 84 and 178, respectively, the variable ‘binary basicity’ is used without defining it. OK. When the definition of an abbreviation has been given in the manuscript there is no need to repeat it several times in later chapters. In the experimental methods, all the details concerning every equipment and their process parameters used must be included in Ch 2.2 and its sub-chapters. In the present form of the manuscript, the information given about the analytical methods and procedures is totally insufficient for any third person to repeat the experiments and verify the analytical results.
OK.
How the concentration of metallic iron (Eq. (1) and rows 113-114) was determined on p. 5?
No explanation nor reference to the methods could be found in the revised manuscript.
In the same context, on p. 5, the variable ‘smelting separation index’ should be defined using an equation.
On page 6, rows 130-131, the L/S ratio of 300 rpm is mentioned. What is that?
The reply seems to confuse with an expression of the solid-to-liquid ratio used and the rotation speed of the leaching experiment in the same sentence.
On p. 6, rows 148-152, in Eq. (4) a variable k1 is mentioned as ‘the reference intensity’. That very factor must be defined in more detail in text.
One may ask: ‘diffraction peak intensity’ of what. Please, be precise in your output.
The ash analysis of the used soft coal has a total of about 70 % (Table 5). What is the rest?
Ash of a coke or e.g. anthracite cannot have LOI ≠ 0!
Figures 4-6 use the expression ‘Iron grade’ as ordinate axis. It is of interest to know what the authors mean by these iron assay values between 38 and 40 % in a solid-state reduction experiment producing metallic iron as the product? What is the rest in the metal phase, e.g. in Table 8?
Please explain this issue in the experimental part, preferably by an equation. Metal phase is metallic (an iron alloy) and gangue is oxidic (‘slag’), and they do not mix even at very high temperatures. The explanation does not make sense at all! Table 7 shows the estimated assays of the pre-reduced pellets, not that of the iron alloy. Thus, the expression ‘iron grade’ needs a clear and sound description in Ch 2.2, preferably in form of an equation.
Please, explain this in text to your readers and not to the me. It is a question of a confusing style and inadequate content of the manuscript!
On p. 9, rows 209-216, complex chemical reactions have been presented for explaining the chemical processes occurring in the pre-reduction and phase separation (melting) steps. The evaluation on the direction of reaction is carried out based on the Gibbs energy change only, in spite of the fact that reactions (7) - (8) and (11) - (12) contain gaseous reactants on both sides of the equation. Then, the direction will be defined by the ratio of CO2-to-CO in the system and not by the standard Gibbs energy change alone.
OK.
The viscosity data on p. 9-10 has a typing error in the unit used.
OK.
On p. 10, figure 8, the authors use the phrase ‘quantity of liquid’ probably meaning the mass or amount fraction?
Please, explain in text whether the fraction of liquid phase is given as mass fraction (or wt%), or as amount fraction (or mol%).
On p. 10, row 234 and later, the authors launch a new variable ‘the smelting separation index’ without defining it.
No explanation for expression ‘smelting separation index’ could be found in the text of v2 (row 256).
The authors added coke up to 20 wt% of the charge (C/Fe ≈6) in the melting separation of the pre-reduced material. Did you remove the excess carbon from the pre-reduced product prior to melting and what was the reason for adding such a massive amount of reductant in the phase separation step? The reasons for selecting the processing conditions in each step should be clarified in the Materials and methods Chapter.
No explanation for the above could be identified in text of v2, not in Ch 2 or in Ch 3.
Figure 14 and its EDS spectra contain very little information but taking almost a full page, and the EDS spectra can be condensed to a short table without jeopardizing the message.
The authors seem to prefer showing the EDS spectra in the manuscript, but add a new table for numerical results. This decision of presenting the results both in graphical form and numerically is a bit confusing and may be justified later by the Editors.
The roasting conditions on p. 14 must be relocated in the manuscript and specified in detail in the Materials and methods Chapter, including the possible pre-treatments made with the raw materials.
There can exist no uncertainty in the information and data given in Materials and methods Chapter or between them and those reported in the Results Ch. Instead, all data reported in a manuscript must conform throughout the manuscript and may contain no hidden agenda, not explained properly and in detail to the reader.
On p. 14, the figure caption should be essentially self-explaining and give all the necessary data required to understand the results and their boundary conditions.
OK.
Before any conclusions can be drawn from the results, Ch 3 must include an analysis of the present e.g. energy, additive and reductant consumption data of the new method compared with the available technologies of today, such as the blast furnace. Only a full comparison of the obtained results with state-of-the art allows you to make the conclusions in Ch 4.
I could not find any analysis of the energy or reductant consumption analysis in v2. Instead, on rows 353 to 358, several claims and statements are presented which are not supported by the present results. A typical false claim is ‘the blast furnace, the energy consumption and the amount of additive and reductant are about half.’ As presented earlier, the reductant consumption in this flow sheet is more than 3x that of the BF process practiced today!
On p. 14 and later, the phrase ‘flow scheme’ may refer to the more conventional phrase ‘flow sheet’?
OK.
Some new comments about v2:
The chemical compositions of pig iron and alkaline leaching tailings have totals less than 100% in Table 9 (on p. 17). What is the rest? The equipment used in the work have been specified mostly by the type numbers only. It would be useful to include their manufacturers in the text, as well, in Ch 2.2.
Comments for author File: Comments.pdf
Author Response
Comments and needs for modifications:
(1) In general, the English needs upgrading by a native speaker. There are also a number of spelling errors in the manuscript which indicates that the authors have not utilized the word processor’s checker feature before submitting it.
Author’s response: The author has been used the language correction services.
(2) Table 4 gives measured elemental compositions of the phases in the ore. The values have been reported with an extremely and unexceptionally high precision of two decimals, but no information was presented on the validated accuracies of the analytical techniques used for the raw materials. The same is valid with the various results given later in the manuscript, such as yields and grades. Besides, the analytical tools used for the products were presented in Ch 2.3 without any details of the external standards used and the accuracies/uncertainties obtained in the actual measurements.
Author’s response: The accurate concentrations, yields and the detailed descriptions of the equipment and analytical methods have been presented in the paper.
(3) How the concentration of metallic iron (Eq. (1) and rows 113-114) was determined on p. 5?
Author’s response: The concentration of metallic iron was determined by chemical titration based on the national standards (GB/T 24194-2009), and the reference has been quoted in the paper.
(4) On page 6, rows 130-131, the L/S ratio of 300 rpm is mentioned. What is that?
Author’s response: The author wrote in the article L/S ratio of 10 ml/g and 300 rpm, not L/S ratio of 300 rpm. And the author has been modified in this paper.
(5) On p. 6, rows 148-152, in Eq. (4) a variable k1 is mentioned as ‘the reference intensity’. That very factor must be defined in more detail in text.
Author’s response: The reference intensity is namely diffraction peak intensity and the author has been explained the definition of diffraction peak intensity in this paper.
(6) The ash analysis of the used soft coal has a total of about 70 % (Table 5). What is the rest?
Author’s response: The author re-measured the ash analysis of the soft coal, and the data has been modified. The rest of the chemical compositions is MgO, TiO2, K2O, Na2O, P2O5, SO2 and trace element compounds.
(7) Figures 4-6 use the expression ‘Iron grade’ as ordinate axis. It is of interest to know what the authors mean by these iron assay values between 38 and 40 % in a solid-state reduction experiment producing metallic iron as the product? What is the rest in the metal phase, e.g. in Table 8?
Author’s response: The iron grade refers to the content of total iron in the pre-reduced pellets, which including metallic iron content and the iron content in “FeO”. The rest in the metal phase is “FeO”.
(8) On p. 10, figure 8, the authors use the phrase ‘quantity of liquid’ probably meaning the mass or amount fraction?
Author’s response: The quantity of liquid means the mass fraction of liquid phase.
(9) On p. 10, row 234 and later, the authors launch a new variable ‘the smelting separation index’ without defining it.
Author’s response: The smelting separation index includes the content of total iron in the pig iron and the recovery of iron. And it could be found in the 2.2.2 Pre-reduction-smelting separation process Chapter.
(10) The authors added coke up to 20 wt% of the charge (C/Fe ≈ 0.6) in the melting separation of the pre-reduced material. Did you remove the excess carbon from the pre-reduced product prior to melting and what was the reason for adding such a massive amount of reductant in the phase separation step? The reasons for selecting the processing conditions in each step should be clarified in the Materials and methods Chapter.
Author’s response: The author removed the excess carbon from the pre-reduced product prior to melting. The reason for adding such a massive amount of reductant in the phase separation step is the low metallization rate of pre-reduced pellets. And the main iron-containing phases are fayalite and hercynite, which are difficult to reduce by CO. The reasons for selecting the processing conditions in each step could be found in the 2.2.2 Pre-reduction-smelting separation process Chapter.
(11) Figure 14 and its EDS spectra contain very little information but taking almost a full page, and the EDS spectra can be condensed to a short table without jeopardizing the message.
Author’s response: The purpose of the graphical is to present the microstructure of the main phases in the slag obtained from different basicity. And the purpose of the numerical is to present the chemical compositions of the main phases.
(12) The roasting conditions on p. 14 must be relocated in the manuscript and specified in detail in the Materials and methods Chapter, including the possible pre-treatments made with the raw materials.
Author’s response: The roasting conditions have been presented in the manuscript and specified in detail in Materials and Methods Chapter.
(13) Before any conclusions can be drawn from the results, Ch 3 must include an analysis of the present e.g. energy, additive and reductant consumption data of the new method compared with the available technologies of today, such as the blast furnace. Only a full comparison of the obtained results with state-of-the art allows you to make the conclusions in Ch 4.
Author’s response: Baev et al investigated the heat exchange and reduction in high-alumina charges in the Blast furnace. The results showed that due to the lower reducibility of high-alumina iron ore, the coke and energy consumption were up to 1200Kg/(ton of pig iron) and 460 kWh/(ton of pig iron) in the blast furnace smelting process, respectively. He et al also presented that the coke and energy consumption of the direct slag-iron smelting reduction were 1463.30Kg/(ton of pig iron) and 432.29 kWh/(ton of pig iron). The energy and reductant consumption of the pre-reduction-smelting separation to treatment iron ore were decreased with increasing the metallization rate of pre-reduced pellets [Gao et al., Technical analysis on ironmaking process of rotary kiln pre-reduction and smelting by coal and oxygen]. According to the reference [Gao et al., 2018], it can be calculated that the energy and reductant consumption of this process is 380 kWh/(ton of pig iron) and 1014 kg/(ton of pig iron).
（14）The chemical compositions of pig iron and alkaline leaching tailings have totals less than 100% in Table 9 (on p. 17). What is the rest? The equipment used in the work have been specified mostly by the type numbers only. It would be useful to include their manufacturers in the text, as well, in Ch 2.2.
Author’s response: The rest in the alkaline leaching tailings is crystal water. The reason of chemical compositions of pig iron is less than 100% is that uneven sampling or oxidized during sampling. The manufactures of the equipment have been presents in the text.
Round 3
Reviewer 1 Report
The abbreviation et al. stands for a Latin phrase 'et alii' ('and others') and, therefore, it always must be accompanied by full stop!
Author Response
The abbreviation et al. stands for a Latin phrase 'et alii' ('and others') and, therefore, it always must be accompanied by full stop!
Author’s response：The “et al” has been modified to “et al.”.
