Advances in Integrated Extraction of Valuable Components from Ti-Bearing Slag

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This article discusses various methods of extracting valuable components from titanium-containing slags. It examines hydrometallurgical methods based on acid use, electrochemical and pyrometallurgical methods, including modern ones that use plasma and selective precipitation to enrich titanium in one phase. Overall, the article is of interest to specialists in the field, though it has its shortcomings. It ends with an advertisement for the authors' method, though preceding chapters do not highlight its advantages over other approaches. It should be clearer which method their technology relates to and what results it will produce apart from improved mixing.

Specific comments:

l. 17 The abbreviation TBS appears for the first time and be written out in full.
Fig. 1. There is an obvious overlap of captions in the upper left corner.
l. 389. The term carbonization is used in one place in the text, while carburization is used elsewhere. Consistency must be ensured.
Equations 18-19 should be rewritten.
l. 449 The abbreviation DC should be written out in full.

Author Response

Comments 1: l. 17 The abbreviation TBS appears for the first time and be written out in full.

Response 1: Thank you for pointing this out. We agree with this comment. Therefore, we have written out "TBS" in full as "Ti-Bearing Slag (TBS)" at its first appearance in the manuscript. This change can be found on page 1 (line 12) in the revised manuscrift.

Comments 2: Fig. 1. There is an obvious overlap of captions in the upper left corner.

Response 2:  Thank you for your comment. We agree with this comment. Therefore, we have adjusted the layout of the captions in Figure 1 to eliminate the overlap. This change can be found in Figure 1 on page 2 (line 44) in the revised manuscript.

Comments 3: l. 389. The term "carbonization" is used in one place in the text, while carburization is used elsewhere. Consistency must be ensured.

Response 3: Thank you for pointing this out. We agree with this comment. Therefore, we have standardized the term to "carbonization" throughout the manuscript. This change can be found on page 13 (line 400) and page 14 (line 434) in the revised manuscript.

Comments 4: Equations 18-19 should be rewritten.

Response 4: Thank you for this suggestion. We agree with this comment. Therefore, Equations 18 and 19 have been rewritten for clarity-specifically, we standardized the chemical symbol format. This change can be found on page 14 (line 450 and 451) in the revised manuscript.

Comments 5: l. 449 The abbreviation DC should be written out in full.

Response 5: Thank you for pointing this out. We agree with this comment. Therefore, we have written out "DC" in full as "Direct Current (DC)" at its first appearance. This change can be found on page 15 (line 460-461) in the revised manuscript.

Reviewer 2 Report

Comments and Suggestions for Authors

Please address the following comments:

1. The full form of TBS should be included in the abstract.

2. Table 3 and Figure 4 should be removed, and the information on crystal structure can be reduced. Sections 2.1 and 2.2 should be merged.

3. The first paragraph of section 3 is redundant as it is already mentioned in the introduction and should be deleted.

4. The method for evaluating Gibbs free energy values at different temperatures using Origin software (Figure 5) should be explained.

5. The literature review for each process is superficial; it should include information on how subsequent studies have made improvements and provide a stronger scientific basis for recovering Ti from TBS.

6. The description of how a diagram was created is not necessary and should be removed.

7. The authors are suggested to include a summary table for each process, detailing the TBS composition, optimum experimental conditions, and the percentage of titanium recovery.

8. A cost analysis for processing TBS using all the mentioned methods should be included.

9. The reference cited in the first paragraph of section 3.3 does not support the corresponding statement, and similar citation errors are found elsewhere. The authors must recheck all references for accuracy and relevance.

10. A recent review titled "Advances in the integrated recovery of valuable components from titanium-bearing blast furnace slag: A review" (Sustainable Materials and Technologies, Volume 44, July 2025, e01384) has been published. The authors should clarify the novelty of their study in relation to this existing review.

Author Response

Comments 1: The full form of TBS should be included in the abstract.

Response 1: Thank you for pointing this out. We agree with this comment. Therefore, we have written out "TBS" in full as "Ti-Bearing Slag (TBS)" at its first appearance in the manuscript. This change can be found on page 1 (line 12) in the revised manuscrift.

Comments 2: Table 3 and Figure 4 should be removed, and the information on crystal structure can be reduced. Sections 2.1 and 2.2 should be merged.

Response 2: Thank you for your suggestion. We understand your concern about content conciseness. However, we would like to emphasize that Table 3 and Figure 4 are essential for our study: Table 3 provides precise crystallographic parameters of titanium-bearing mineral phases (a fundamental basis for analyzing structural characteristics), while Figure 4 intuitively displays crystal ball-and-stick models (greatly aiding readers' understanding of the structural basis for titanium extraction). Thus, we have retained them. To more accurately reflect the critical nature of this data and to enhance clarity, we have renamed Table 3 to “Crystallographic structural parameters of major Ti-bearing phases” and revised the accompanying text that introduces the table to explicitly state that these parameters are “decisive for the kinetics and efficiency of titanium extraction”. This change can be found on page 5 (lines 149-155) in the revised manuscrift.

Regarding Sections 2.1 and 2.2: We appreciate your consideration for integration but believe they should remain separate. Section 2.1 gives a broad overview of TBS classification and overall properties, while Section 2.2 delves into detailed chemical components and mineral phases. This "general - to - specific" structure ensures logical understanding, so we've kept them distinct with a smooth transition.

Comments 3: The first paragraph of section 3 is redundant as it is already mentioned in the introduction and should be deleted.

Response 3: Thank you for your comment. We appreciate your concern about redundancy, we have carefully considered it but believe this paragraph isessential for the following reasons:  This paragraph serves as a crucial transition, defining the essence of titanium extraction from TBS and introducing the four principal industrial methods to be analyzed. It provides the necessary context and a logical framework for the subsequent subsections (3.1-3.4). Removing it would make the detailed analysis of each method appear abrupt and disjointed, potentially compromising the structural coherence and readability of the entire section. We have further refined the language of this paragraph to ensure it is concise and purely informational, addressing any concerns about redundancy. This change can be found on page 7(lines 201-209) in the revised manuscript.

Comments 4: The method for evaluating Gibbs free energy values at different temperatures using Origin software (Figure 5) should be explained.

Response 4: Thank you for your comment. We fully agree that the method for evaluating Gibbs free energy values needs to be clarified. We have supplemented detailed explanations that the Gibbs free energy values (ΔG) for each reaction were calculated using the HSC Chemistry 9 software. Origin 2024 software was then used to visualize the calculated ΔG-T data and generate the composite diagram presented in Figure 5. Additionally, we have renamed Figure 5 to “Ellingham diagram for the reactions of key oxides in high-titanium blast furnace slag with concentrated sulfuric acid during calcination”. The term "Ellingham diagram" precisely denotes the standardized ΔG-T analysis performed, enhancing the technical accuracy of the figure. The changes can be found on page 9 (lines 258-265) and the revised name of  Figure 5 can be found on page 9 (line 275) in the revised manuscript.

Comments 5: The literature review for each process is superficial; it should include information on how subsequent studies have made improvements and provide a stronger scientific basis for recovering Ti from TBS.

Response 5: Thank you for your comment. We fully agree that enhancing the depth of the literature review by highlighting technological progress and its scientific foundation is essential for the manuscript. We have thoroughly revised the literature review for each extraction process in Section 3 to address this concern. The revisions now explicitly highlight the limitations of conventional methods, detail how subsequent studies have made technological improvements, and provide a stronger scientific basis for each process. These changes can be found on page 8 (lines 235-242) in section 3.1, page13 (lines 388-399) in section 3.2.1 of section 3.2, page 15-16 (lines 489-499) in section 3.2.2 of section 3.2, page 17-18 (lines 564-577) in section 3.3, and page 20-21 (lines 672-686) in section 3.4 in the revised manuscript.

Comments 6: The description of how a diagram was created is not necessary and should be removed.

Response 6: Thank you for your constructive comment. We fully agree that the creation methods of the diagrams should be removed. These changes can be found on page 4 (Figure 3. line 124), page 7 (Figure 4. line 184), page 9 (Figure 5. line 275), page 10 (Figure 6. line 298), page 11 (Figure 7. line 336), page 12 (Figure 8. line 355), page 14 (Figure 9. line 441), page 15 (Figure 10. line 472), page 17 (Figure 11. line 551), page 19 (Figure 12. line 629), page 20 (Figure 13. line 654-655), page 22(Figure 14. line 728), page 22(Figure 15. line 730), page 23(Figure 17. line 758), page 26(Figure 18. line 810) in the revised manuscript.

Comments 7: The authors are suggested to include a summary table for each process, detailing the TBS composition, optimum experimental conditions, and the percentage of titanium recovery.

Response 7: Thank you for your constructive comment. We fully agree that a summary table would significantly enhance the clarity and comparative analysis of the different extraction processes.We have added Section 3.5 to present a comparative analysis of different titanium extraction technologies. Additionally, we have summarized the TBS composition, optimum experimental conditions, and titanium recovery rate of various titanium extraction methods, which are listed in Table 4 of Section 3.5 on Pages 24–25 of the revised manuscript. These changes can be found on page 24-25(line 781-786) in the revised manuscript.

Comments 8: A cost analysis for processing TBS using all the mentioned methods should be included.

Response 8: Thank you for your constructive comment. We acknowledge cost is key for industrial feasibility, but precise cost analysis is challenging due to the pilot-scale nature of most technologies discussed (lacking industrial CAPEX/OPEX data). Instead, we have addressed economic potential indirectly. Table 4 now includes key cost drivers like energy consumption and environmental impact (e.g., CO₂ emissions, waste generation), which serve as robust proxies for comparative economic assessment at this stage.

Comments 9: The reference cited in the first paragraph of section 3.3 does not support the corresponding statement, and similar citation errors are found elsewhere. The authors must recheck all references for accuracy and relevance.

Response 9: Thank you for your constructive comment. We fully agree to replace the references with weak support to enhangce the rigor and persuasiveness of the paper’s academic arguments. We have replaced the weakly supported references with more direct and authoritative ones. And we have also revised other inappropriate references in the manuscript. The changes can be found on page 32(line 1121-1122), page 25 (line 799 ), page 25 (line 801), page 25 (line 804 ), page 26 (line 823 ), page 34-35(line 1225-1273 ), in the revised manuscript. The detailed revisions are as follows:

(1) We have replaced the less relevant reference [121] (Yang et al., Vacuum, 2024) with the more appropriate citation [121] (Ma et al., Journal of Chongqing University, 2019), which provides stronger support for the discussed context.

(2) We have revised the citation in the first sentence of the second paragraph in Section 4 of the original manuscript: the original [170-175] has been changed to [170-174], with the less relevant Reference [173] ("Jiwei Wulian Group Co., Ltd. Jiwei Wulian's 'Steel Brain': Playing a 'Sandwich' Role to Boost Intelligent Steelmaking. 2B Network 2021. http://www.2b.cn/qiyexinwen/72493.html#.") removed.

(3) We have revised the citation in the second sentence of the second paragraph in Section 4 of the original manuscript: the original [176-185] has been changed to [175-180], with the following less relevant Reference references removed:

[177] Wang, Q.Q.; Sun, L.; Cao, Y.; Wang, X.; Qiao, Y.; Xiang, M.T. Recovery of copper and cobalt from waste rock in Democratic Republic of Congo by gravity separation combined with flotation. Trans. Nonferrous Met. Soc. China 2025, 35(2), 602-612;

[178] Amosah, M.E.; Zhou, J.; Galvin, K.P. Fourth generation gravity separation using the Reflux Classifier. Miner. Eng. 2025, 224, 109216;

[179] Sun, J.J.; Dong, L.Y.; Zhang, T.F.; Shen, P.L.; Liu, D.W. Efficient recovery of copper from copper smelting slag by gravity separation combined with flotation. Chem. Eng. J. 2024, 494, 153159;

[180] Wang, Z.W.; Gao, J.T.; Lan, X.; Guo, Z.C. A green method to clean copper slag and rapidly recover copper resources via reduction-sulfurizing smelting and super-gravity separation at low temperature. J. Hazard. Mater. 2024, 468, 133834;

[184] Han, J.Q.; Zhang, J.H.; Chen, X.; Zhang, J.; Zhang, L.; Tu, G.F. Effect of rutile crystal shapes on its settlement. Trans. Nonferrous Met. Soc. China 2020, 30(10), 2848−2860.

(4) We have revised the citation in the third sentence of the second paragraph in Section 4 of the original manuscript: the original [186-202] has been changed to [181-188], with the following less relevant references removed:

[186] Bolzon, L.; Raynova, S.; Yang, F. An alternative method to manufacture Ti alloys from particulate materials. Powder Technol. 2021, 380, 341-248;

[193] Wang, Y.L.; Meng, W.Y.; Hu, X.B.; Yao, Y.H.; Wang, H. Reduction and reconstruction of vanadium-containing steel slag at high temperature. J. Environ. Chem. Eng. 2023, 11(6), 111320;

[196] Lin, Y.H.; Zheng, B.; Luo, L.G.; Jia, Y.L.; Zhang, L.Q. The Online Research of B₂O₃ on Crystal Behavior of High Ti-Bearing Blast Furnace Slag. J. Chem. 2019, (4), 5498325.

[197] Yan, B.J.; Huang, X.G.; Zhao, W.; Li, P.; Guo, H.W.; Yang, M.T. An On-line Continuous Treatment Method for Molten Titanium-bearing Blast Furnace Slag (Invention Patent). China: ZL202011222798.6, 2022.

[198] Hao, J.; Dou, Z.H.; Wan, X.Y.; Zhang, T.A.; Wang, K. Interphase migration and enrichment of lead and zinc during copper slag depletion. Trans. Nonferrous Met. Soc. China 2024, 34(9), 3029-3041.

[199] Ye, S.Y.; Liu, T.; Wan, Q.; Zhang, Y.M.; Zheng, Q.S. Efficient recovery of valuable elements from oxygen-rich alkaline leaching solution of chrome-vanadium slag using selective crystallization separation process. Sep. Purif. Technol. 2025, 362, 131932.

[200] Nayak, P.K.; Moore, D.T.; Wenger, B.; Nayak, S.; Haghighirad, A.A.; Fineberg, A.; et al. Mechanism for rapid growth of organic–inorganic halide perovskite crystals. Nat. Commun. 2016, 7(1), 13303.

[201] Fa, H.L.; Wang, R.X.; Xu, Z.F.; Duan, H.M.; Chen, D.F. The effect of B₂O₃ on the structure and properties of titanium slag melt by molecular dynamics simulations. J. Mater. Res. Technol. 2021, 15, 1046-1058.

[202] Cao, S.H.; Liu, Z.H.; Lu, X.W.; Zhang, L.R.; Li, Q.H.; Xia, L.G. The Phase Transition and Element Distribution of Copper Smelting Slag in the Cooling-Sulfidation Process. Metall. Mater. Trans. B 2023, 54(2), 969-979.

Comments 10: A recent review titled "Advances in the integrated recovery of valuable components from titanium-bearing blast furnace slag: A review" (Sustainable Materials and Technologies, Volume 44, July 2025, e01384) has been published. The authors should clarify the novelty of their study in relation to this existing review. 

Response 10: Thank you for your constructive comment. We thank you for bringing this recent and relevant published review Advances in the integrated recovery of valuable components from titanium-bearing blast furnace slag: A review. We have carefully studied this review. While the review mentioned above provides a valuable broad overview of various technologies for treating titanium-bearing blast furnace slag (TBS), our work offers a distinct and deeper contribution in the following aspects: Firstly, rather than a comprehensive survey, our study provides a critical and in-depth analysis of the intrinsic limitations (e.g., acid mist emission and colloidal passivation in acid leaching, high energy consumption and carbon emissions in pyrometallurgical reduction, polarization in electrolysis, thermodynamic-kinetic conflicts in selective precipitation) of the four fundamental extraction routes. We delve into the scientific basis for recent improvements (e.g., the mechanism of concentrated acid roasting activation to suppress colloid formation, the use of gaseous clean reductants to reduce energy intensity, the role of liquid metal cathodes in altering deposition kinetics, the application of Stokes' law and hypergravity in separation), which is a key focus of our work beyond the scope of a typical review. Secondly, The most significant novelty of our work is the proposition of an original technical pathway: “Online conditioning driven by waste heat - mineral phase reconstruction - directional crystallization - optimized liberation”. This proposed route integrates the advantages of multiple methods into a coherent, efficient, and industrially potential process. This forward-looking, solution-oriented proposal for a specific integrated flowsheet is not presented in the compared review.

Reviewer 3 Report

Comments and Suggestions for Authors

• What is the difference between the present review and “Advances in the integrated recovery of valuable components from titanium-bearing blast furnace slag: A review”
• Quantified results should be added to the abstract.
• Do not use a direct quote in the abstract.
• Figures from refs need permission.
• Summarize lines 35-85.
• Lines 86-88: Leaching and precipitation are not synonymous. One is extraction from a solid, and the second is a continuation of leaching, not parallel for comparison.
• Lines 119-121: why use “…” without permission and ref.
• Where are the refs in the rows of Table 1, Table 3?
• Please quantify the results in the conclusion.

Author Response

Comments 1: What is the difference between the present review and “Advances in the integrated recovery of valuable components from titanium-bearing blast furnace slag: A review”

Response 1: Thank you for your constructive comment. We greatly appreciate you pointing out the need to clarify the differences between the existing literature and our study. This will be extremely helpful for us to better understand the research trends in the same field. After a detailed comparison between this review and the recently published Advances in the integrated recovery of valuable components from titanium-bearing blast furnace slag: A review, we clarify the key differences in the following two aspects: Firstly, the focus of the research scope differs. The referenced review centers on the "integrated recovery of multiple valuable components (e.g., Ti, V, Fe)" from titanium-bearing blast furnace slag, with its core being a summary of technical progress in "synergistic extraction of multi-components". In contrast, this review concentrates exclusively on the "efficient extraction of titanium components". It deeply analyzes the mechanistic limitations of four mainstream titanium extraction technologies (e.g., colloidal passivation in acid leaching, high energy consumption in pyrometallurgy, polarization in electrolysis, thermodynamic-kinetic conflicts in selective precipitation) and explores targeted improvement paths, achieving a more in-depth and focused discussion on titanium recovery. Secondly, the contribution of technical content varies. The referenced review only summarizes existing mature technologies and does not propose new technical solutions. This review, based on systematic analysis of current technology bottlenecks, innovatively puts forward an integrated technical route of "waste heat-driven online conditioning - mineral phase reconstruction - directional crystallization - optimized liberation". This route specifically addresses the key issues of "difficult large-scale application" and "low titanium recovery rate" in existing processes, providing a novel technical direction for the industrialization of titanium extraction from titanium-bearing slag.

Comments 2: Quantified results should be added to the abstract.

Response 2: Thank you for your constructive comment. We full agree that inclusion of quantified results is crucial for a comprehensive abstract. Accordingly, we have revised the abstract to incorporate key quantitative results. The changes can be found on page 1 (line 12-34) in the revised manuscript.

Comments 3: Do not use a direct quote in the abstract.

Response 3: Thank you for your constructive comment. We full agree that the direct quotes should not be included in the abstract. We have followed this suggestion and removed all direct quotations from the abstract, replacing them with more objective academic paraphrasing. The changes can be found on page 1 (line 12-34) in the revised manuscript.

Comments 4: Figures from refs need permission.

Response 4: Thank you for your comment regarding figure permissions. We would like to clarify that all figures in the manuscript (including process flowcharts and comparison diagrams) were originally created by the authors based on our understanding of the relevant research concepts. These figures were not directly copied or adapted from pre-existing figures in the references. Therefore, permission is not required.

Comments 5: Summarize lines 35-85. 

Response 5: Thank you for your constructive comment. We full agree that lines 35-85 in the introduction should be more concise. As requested, we have systematically summarized this section, and the detailed revisions can be found on Pages 1-2 (Lines 38-67) in the revised manuscript.

Comments 6: Lines 86-88: Leaching and precipitation are not synonymous. One is extraction from a solid, and the second is a continuation of leaching, not parallel for comparison.

Response 6: Thank you for your constructive comment. We agree that ‘leaching’ and ‘precipitation’ are not parallel concepts. We have revised the sentence to clarify the categorization by using broader, more accurate terms that represent distinct technological routes rather than specific unit operations. The changes can be found on Pages 2-3(lines 69-70) in the revised manuscript.

Comments 7: Lines 119-121: why use “…” without permission and ref.

Response 7: Thank you for your constructive comment. We apologize for the confusion. The phrase enclosed in quotation marks is not a direct quote from another source but rather the name of a novel integrated technical route originally proposed and developed by our research group in this study. Therefore, no external permission or reference is required. We have revised the sentence to make this originality clearer. The detailed revisions can be found on Pages 3 (Lines 103-106) in the revised manuscript.

Comments 8: Where are the refs in the rows of Table 1, Table 3?

Response 8: Thank you for your constructive comment. We fully agree that clarifying data sources in the tables is essential. We have added notes to both Table 1 and Table 3 in the revised manuscript. Specifically, the data in Table 1 are sourced from Reference [40], while the crystal lattice parameters in Table 3 were generated through simulations performed on the Materials Explorer online platform. The changes can be found on Pages 5 (Line 131) and Pages 6 (Line 156) in the revised manuscript.

Comments 9: Please quantify the results in the conclusion.

Response 9: Thank you for your constructive comment.We fully agree that quantifying the results in the conclusion is essential.We have supplemented relevant quantitative results and rewritten the conclusion with further optimization. The changes can be found on Pages 26-27 (Line 837-855) in the revised manuscript.

Reviewer 4 Report

Comments and Suggestions for Authors

I received a review article titled "Advances in Integrated Extraction of Valuable Components from Ti-bearing slag" for review. The paper is of good scientific quality, and the graphs and tables are clear and comprehensible. The paper is based on current literature and requires only minor editorial corrections.

1. The abstract should be rewritten to attract the reader's attention better and highlight the article's novelty.
2. Keywords: They are not well prepared.
3. Some diagrams, such as Figures 6 and 8, require standardisation. Furthermore, Figure 8 is difficult to read.
4. In Figure 1, some data are shifted, and the sum exceeds 100%.
5. Figure 4 – superscripts and subscripts are missing.
6. Equation 9 requires balancing—similarly, some equations in Figure 6.
7. Some figure captions require correction. They also require standardisation and adjustment to the editorial office's requirements.
8. Incorrect notation of reactions 18 and 19.
9. Figure 16 – missing subscripts for oxides.
10. The conclusion should be revised in its entirety. It contains errors and is poorly written.
11. The references should be reviewed and consolidated.
12. The entire manuscript must be carefully proofread.

I have no additional objections. I recommend it for publication in Metals after minor revision.

Author Response

Comments 1:The abstract should be rewritten to attract the reader's attention better and highlight the article's novelty.

Response 1: Thank you for your constructive comment. We fully agree that a compelling abstract is crucial for highlighting the study’s core value and attracting readers’ attention. We have comprehensively rewritten the abstract in accordance with your requirements. The changes can be found on page 1 (line 12-34) in the revised manuscript.

Comments 2: Keywords: They are not well prepared.

Response 2: Thank you for your constructive comment. We fully agree with your suggestion and have optimized the keywords to better reflect the core content of the entire manuscript. The changes can be found on page 1 (line 35-37) in the revised manuscript.

Comments 3: Some diagrams, such as Figures 6 and 8, require standardisation. Furthermore, Figure 8 is difficult to read.

Response 3: Thank you for your constructive comment. We fully agree that the figures need standardization. We have standardized Figures 6 and 8 accordingly. In particular, Figure 8 has been thoroughly redesigned to improve clarity and readability. These changes can be found on pages 10 (line 297) and 12 (line 354) in the revised manuscript.

Comments 4: In Figure 1, some data are shifted, and the sum exceeds 100%.

Response 4: Thank you for your constructive comment. We agree with this comment. Therefore, we have adjusted the layout of the captions in Figure 1 to eliminate the overlap. This change can be found on page 2 (line 44) in the revised manuscript.

Comments 5: Figure 4 – superscripts and subscripts are missing.

Response 5: Thank you for your constructive comment. We fully agree with this comment. We have added the missing superscripts to ensure the accuracy and standardization of the chemical symbols in figure 4. The changes can be found on page 7 (line 183) in the revised manuscript.

Comments 6: Equation 9 requires balancing—similarly, some equations in Figure 6.

Response 6: Thank you for your constructive comment. We fully agree with this comment. We have balanced Equation 9 and also checked and balanced the relevant equations in Figure 6 to ensure their accuracy.The changes can be found on page 9 (line 289) and page10 (Figure 6. line 298) in the revised manuscript. 

Comments 7: Some figure captions require correction. They also require standardisation and adjustment to the editorial office's requirements.

Response 7: Thank you for your constructive comment. We fully agree with the need for standardization of figure captions. All figures have been reviewed and revised in accordance with the editorial office's requirements. The changes can be found on page 2 (Figure 1, line 45 ), page 2 (Figure 2, line 47 ), page 4 (Figure 3, line 124), page 7 (Figure 4, line 184), page 9 (Figure 5, line 275), page 10 (Figure 6, line 298), page 11 (Figure 7, line 336), page 12 (Figure 8, line 355), page 14 (Figure 9, line 441), page 15 (Figure 10, line 472), page 17 (Figure 11, line 551), page 19 (Figure 12, line 629), page 20 (Figure 13, line 654), page 22 (Figure 14, line 728), page 22 (Figure 15, line 730), page 23 (Figure 16, line 741), page 24 (Figure 17, line 758), page 26 (Figure 18, line 810) in the revised manuscript.

Comments 8: Incorrect notation of reactions 18 and 19.

Response 8: Thank you for your constructive comment. We fully agree with this comment. We have revised the  Reactions 18 and 19 in accordance with standard notation.The changes can be found on page 14 (line 450,451 ) in the revised manuscript.

Comments 9: Figure 16 – missing subscripts for oxides.

Response 9: Thank you for your constructive comment. We fully agree with this comment. We have supplemented the subscripts for the oxide chemical formulas in Figure 16 as required to ensure the notation is accurate and standardized. The changes can be found on page 23 (Figure 16. line 740 ) in the revised manuscript.

Comments 10: The conclusion should be revised in its entirety. It contains errors and is poorly written.

Response 10: Thank you for your constructive comment. We fully agree with this comment. We have thoroughly revised the Conclusion section to accurately reflect the study's findings and to improve its clarity and scientific rigor. The changes can be found on page 26-27 (line 836-855 ) in the revised manuscript.

Comments 11: The references should be reviewed and consolidated.

Response 11: Thank you for your constructive comment. We fully agree with this comment. We have carefully reviewed and consolidated the references as suggested, ensuring they are relevant and properly support the discussions in the manuscript. The changes can be found on page 25 (line 799 ), page 25 (line 801 ), page 25 (line 804), page 26 (line 823 ), page 34-35(line 1225-1273 ), in the revised manuscript. The detailed revisions are as follows:

(1) We have revised the citation in the first sentence of the second paragraph in Section 4 of the original manuscript: the original [170-175] has been changed to [170-174], with Reference [173] ("Jiwei Wulian Group Co., Ltd. Jiwei Wulian's 'Steel Brain': Playing a 'Sandwich' Role to Boost Intelligent Steelmaking. 2B Network 2021. http://www.2b.cn/qiyexinwen/72493.html#.") removed.

(2) We have revised the citation in the second sentence of the second paragraph in Section 4 of the original manuscript: the original [176-185] has been changed to [175-180], with the following references removed:

[177] Wang, Q.Q.; Sun, L.; Cao, Y.; Wang, X.; Qiao, Y.; Xiang, M.T. Recovery of copper and cobalt from waste rock in Democratic Republic of Congo by gravity separation combined with flotation. Trans. Nonferrous Met. Soc. China 2025, 35(2), 602-612;

[178] Amosah, M.E.; Zhou, J.; Galvin, K.P. Fourth generation gravity separation using the Reflux Classifier. Miner. Eng. 2025, 224, 109216;

[179] Sun, J.J.; Dong, L.Y.; Zhang, T.F.; Shen, P.L.; Liu, D.W. Efficient recovery of copper from copper smelting slag by gravity separation combined with flotation. Chem. Eng. J. 2024, 494, 153159;

[180] Wang, Z.W.; Gao, J.T.; Lan, X.; Guo, Z.C. A green method to clean copper slag and rapidly recover copper resources via reduction-sulfurizing smelting and super-gravity separation at low temperature. J. Hazard. Mater. 2024, 468, 133834;

[184] Han, J.Q.; Zhang, J.H.; Chen, X.; Zhang, J.; Zhang, L.; Tu, G.F. Effect of rutile crystal shapes on its settlement. Trans. Nonferrous Met. Soc. China 2020, 30(10), 2848−2860.

(3) We have revised the citation in the third sentence of the second paragraph in Section 4 of the original manuscript: the original [186-202] has been changed to [181-188], with the following references removed:

[186] Bolzon, L.; Raynova, S.; Yang, F. An alternative method to manufacture Ti alloys from particulate materials. Powder Technol. 2021, 380, 341-248;

[193] Wang, Y.L.; Meng, W.Y.; Hu, X.B.; Yao, Y.H.; Wang, H. Reduction and reconstruction of vanadium-containing steel slag at high temperature. J. Environ. Chem. Eng. 2023, 11(6), 111320;

[196] Lin, Y.H.; Zheng, B.; Luo, L.G.; Jia, Y.L.; Zhang, L.Q. The Online Research of B₂O₃ on Crystal Behavior of High Ti-Bearing Blast Furnace Slag. J. Chem. 2019, (4), 5498325.

[197] Yan, B.J.; Huang, X.G.; Zhao, W.; Li, P.; Guo, H.W.; Yang, M.T. An On-line Continuous Treatment Method for Molten Titanium-bearing Blast Furnace Slag (Invention Patent). China: ZL202011222798.6, 2022.

[198] Hao, J.; Dou, Z.H.; Wan, X.Y.; Zhang, T.A.; Wang, K. Interphase migration and enrichment of lead and zinc during copper slag depletion. Trans. Nonferrous Met. Soc. China 2024, 34(9), 3029-3041.

[199] Ye, S.Y.; Liu, T.; Wan, Q.; Zhang, Y.M.; Zheng, Q.S. Efficient recovery of valuable elements from oxygen-rich alkaline leaching solution of chrome-vanadium slag using selective crystallization separation process. Sep. Purif. Technol. 2025, 362, 131932.

[200] Nayak, P.K.; Moore, D.T.; Wenger, B.; Nayak, S.; Haghighirad, A.A.; Fineberg, A.; et al. Mechanism for rapid growth of organic–inorganic halide perovskite crystals. Nat. Commun. 2016, 7(1), 13303.

[201] Fa, H.L.; Wang, R.X.; Xu, Z.F.; Duan, H.M.; Chen, D.F. The effect of B₂O₃ on the structure and properties of titanium slag melt by molecular dynamics simulations. J. Mater. Res. Technol. 2021, 15, 1046-1058.

[202] Cao, S.H.; Liu, Z.H.; Lu, X.W.; Zhang, L.R.; Li, Q.H.; Xia, L.G. The Phase Transition and Element Distribution of Copper Smelting Slag in the Cooling-Sulfidation Process. Metall. Mater. Trans. B 2023, 54(2), 969-979.

(4) We have revised the citation in the last sentence of the third paragraph in Section 4 of the original manuscript: the original [203-209] has been changed to [189-195].

Comments 12: The entire manuscript must be carefully proofread.

Response 12: Thank you for your constructive comment. We fully agree with this comment. We have carefully and comprehensively proofread the entire manuscript and conducted a thorough check on all the revisions made to ensure the accuracy, consistency, and quality of the content.

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

 Again, what is the difference between the present review and “Advances in the integrated recovery of valuable components from titanium-bearing blast furnace slag: A review”? Compare that in a table. Without proving the novelty of similar works, it cannot be accepted. 

Author Response

Comments 1: Again, what is the difference between the present review and “Advances in the integrated recovery of valuable components from titanium-bearing blast furnace slag: A review”? Compare that in a table. Without proving the novelty of similar works, it cannot be accepted.

 

Response 1: Thank you for your constructive comment. We greatly appreciate you pointing out the need to clarify the differences between our review and the specific work you mentioned—“Advances in the integrated recovery of valuable components from titanium-bearing blast furnace slag: A review”—as well as the requirement to demonstrate novelty via a table.

To address this, we have prepared a comparative table below, which systematically distinguishes the two reviews from the perspectives of research focus, core covered technologies, and novelty highlights, to clearly demonstrate the uniqueness of our work:

Table 1 Core Differences Between This Review and Advances in the Integrated Recovery of Valuable Components from Titanium-Bearing Blast Furnace Slag: A Review

Comparison Dimension	Reference Review: Advances in the Integrated Recovery of Valuable Components from Titanium-Bearing Blast Furnace Slag: A Review	This Review
1. Research Scope & Core Focus	Focuses on the integrated recovery of multiple valuable components (e.g., Ti, V, Fe) from titanium-bearing blast furnace slag. Its core lies in the systematic summary of technical progress in "synergistic extraction of multi-components" without in-depth exploration of a single component.	Focuses exclusively on the efficient extraction of titanium components from titanium-bearing slag (excluding other components), concentrating on technical breakthroughs and bottleneck solutions for this single target component.
2. Depth of Technical Analysis & Focus	Provides procedural and general descriptions of existing mature recovery technologies (e.g., integrated extraction processes), without in-depth analysis of the intrinsic mechanistic limitations of various technologies.	In-depth analysis of the core mechanistic bottlenecks of four mainstream titanium extraction technologies (acid leaching, pyrometallurgy, electrolysis, selective precipitation) — such as colloidal passivation in acid leaching, high energy consumption in pyrometallurgy, polarization in electrolysis, and thermodynamic-kinetic conflicts in selective precipitation — and targeted exploration of improvement paths.
3. Contribution & Innovation in Technical Content	Only summarizes mature reported technical achievements, with no new technical ideas, schemes, or process routes proposed. Its core goal is to "organize the current state of research".	Based on a systematic analysis of existing technical bottlenecks, it innovatively proposes an integrated technical route of "waste heat-driven online conditioning – mineral phase reconstruction – directional crystallization – optimized liberation". This route directly addresses the two key issues of "difficult large-scale application" and "low titanium recovery rate" in existing processes, providing a new technical direction.
4. Research Objective & Value Orientation	Aims to present the "technical panorama" of multi-component recovery from titanium slag, providing references for cross-component comprehensive utilization. Its value leans toward "broad coverage".	Aims to break through the "technical bottlenecks" in titanium component extraction, providing a practical technical path for the industrial recovery of a single high-value component (titanium) from titanium slag. Its value leans toward "in-depth breakthrough".