Improved Process for Separating TiO2 from an Oxalic-Acid Hydrothermal Leachate of Vanadium Slag
Round 1
Reviewer 1 Report
This paper describes the TiO2 separation process from post-leaching solution of vanadium slag. The proposed process consists of two steps. In the first step, oxalic-acid is recovered from the pregnant oxalic-acid leachate by cooling-crystallization method. Then TiO2 is separated from the oxalic-acid recovered leachate by hydrothermal precipitation method.
The results showed that when 15 vol % HCl solution relative to pregnant leachate was added, about 35 % oxalic-acid can be recovered by cooling-crystallization at 5 °C for 3 hours, and anatase TiO2 product with purity of 99.2 % can be obtained by hydrothermal precipitation at 140 °C for 2.5 hours.
The methods and techniques used in the experiments are all well-established. The authors have some publications in this field.
Although the problems being addressed are potential of interest to readership, the manuscript does not meet the required quality standards to be considered for publication.
Abstract: This part is not well written. This paper's major findings and scientific novelty should be emphasized in this part. The current version was just a summary of research methods.
Keywords: There are no keywords in the manuscript.
Introduction part: This manuscript's aims and novelty should be stated more fully in this section.
Figure 6: Font is relatively small. Figure is not apprehensible and transparent.
Tables 1, 4, 5. There are some errors.
References. The number of cited literature is very poor. Additionally, the authors need to correct the writing of references and adjust it to the existing guidelines or some papers that have been published in Metals.
The entire manuscript must be carefully proofread before resubmission.
After major revision, I recommend it for publication in Metals.
Author Response
Responses to Reviewer 1:
Comment 1: Abstract: This part is not well written. This paper's major findings and scientific novelty should be emphasized in this part. The current version was just a summary of research methods.
Authors’ Response: The abstract was reorganized, and the important experimental were presented in the new abstract.
Comment 2: Keywords: There are no keywords in the manuscript.
Authors’ Response: Keywords were added in the new manuscript.
Comment 3: Introduction part: This manuscript's aims and novelty should be stated more fully in this section.
Authors’ Response: The last paragraph of introduction part was reorganized, and the aim and novelty were stated fully.
Comment 4: Figure 6: Font is relatively small. Figure is not apprehensible and transparent.
Authors’ Response: The Figure 6 has been modified, and the errors was corrected.
Comment 5: Tables 1, 4, 5. There are some errors.
Authors’ Response: All Tables were checked and the errors were corrected. In addition, a necessary note was added in the bottom of some Tables.
Comment 6: References. The number of cited literature is very poor. Additionally, the authors need to correct the writing of references and adjust it to the existing guidelines or some papers that have been published in Metals.
Authors’ Response: Some new related literatures were added, and the format of references were corrected.
Reviewer 2 Report
Title: Optimized process for separating TiO2 from an oxalic-acid hydrothermal leachate of vanadium slag
Authors: Qingdong Miao, Ming Li, Guanjin Gao, Wenbo Zhang, Jie Zhang and Baijun Yan
Comments and suggestions which authors may find useful in upgrading manuscript are the following:
1. The word "optimized" in the title is overused. The authors did not use any optimization methods. The authors only studied the influence of various factors on e.g. separation of the TiO2 from the leachate. I advise remove "optimized" from the title and from the manuscript.
2. Why did the authors choose oxalic acid (OA)? Maybe a different organic acid would be cheaper and better than OA?
3. Page 5, Tables 3 and 4: Values in the tables do not add up to 100%. Why? (Table 3 – 99,94%, Table 4 – 99,98%).
4. Page 6, Figure 4: The caption of the figure 4 is inadequate to the figure. (a), (b), (c) suggest that there should be 3 graphs in one.
5. Figure 4: To recover 35% oxalic acid, the authors use 15% vol of concentrated HCl. The recovery percentage of OA is not very high. Is it economical and profitable?
6. Page 8, Figure 7: Figures should be named a, b, c ... and the captions added to the figure 7 caption, e.g. (a) V2O5 content ... ect.
7. Page 9, Figure 8: The same comment as in the case of Figure 7.
8. Other comments:
a) title of the manuscript – please correct “TiO2”,
b) please add keywords,
c) please standardize the units in the manuscript:
- pages 1 and 2: is “pct” but it should be “%”,
- “g”, not “grams”,
- “mL”, not “ml”,
- “h”, not “hours”,
- remove “vol.”, “pp.” and “p.” from references.
Author Response
Comment 1: The word "optimized" in the title is overused. The authors did not use any optimization methods. The authors only studied the influence of various factors on e.g. separation of the TiO2 from the leachate. I advise remove "optimized" from the title and from the manuscript.
Authors’ Response: We completely agree with the opinion of reviewer. And all the words related with “optimized” were removed.
Comment 2: Why did the authors choose oxalic acid (OA)? Maybe a different organic acid would be cheaper and better than OA?
Authors’ Response: The reason of selecting oxalic-acid as leaching agent is to avoid the effect of Fe in the vanadium slag on the leachate, because the Fe can react with H2C2O4 to form FeC2O4 precipitate.
Comment 3: Page 5, Tables 3 and 4: Values in the tables do not add up to 100%. Why? (Table 3 – 99,94%, Table 4 – 99,98%).
Authors’ Response: In these tables, the content of TiO2 was obtained by subtraction of contents of impurities, so only one number after decimal point was adopted. And this was specified in the revised tables.
Comment 4: Page 6, Figure 4: The caption of the figure 4 is inadequate to the figure. (a), (b), (c) suggest that there should be 3 graphs in one.
Authors’ Response: The caption of figure 4 was modified.
Comment 5: Figure 4: To recover 35% oxalic acid, the authors use 15% vol of concentrated HCl. The recovery percentage of OA is not very high. Is it economical and profitable?
Authors’ Response: Thanks for the reminder of reviewer. This issue need to be considered in future work.
Comment 6: Page 8, Figure 7: Figures should be named a, b, c ... and the captions added to the figure 7 caption, e.g. (a) V2O5 content ... ect.
Authors’ Response: Figure 7 was modified, the chemical formula of the impurity was added in the corresponding figure.
Comment 7: Page 9, Figure 8: The same comment as in the case of Figure 7.
Authors’ Response: Figure 8 was modified.
Comment 8: Other comments about the format of writing.
Authors’ Response: All of them were corrected according to advice of reviewer.
Reviewer 3 Report
Dear Authors,
It is an interesting paper. But I have a few remarks.
In the photographs of figure 8, the scaling is not visible.
The bibliographical references are complete but are few. Can you add citations, without giving too much self-citation?
Yours sincerely.
Author Response
Comment 1: In the photographs of figure 8, the scaling is not visible.
Authors’ Response: A clear scaling ruler was added in the photographs of figure 8.
Comment 2: The bibliographical references are complete but are few. Can you add citations, without giving too much self-citation?
Authors’ Response: Some new related literatures were added, and the format of references were corrected.
Round 2
Reviewer 1 Report
I have received a revised version of the manuscript entitled “Optimized process for separating TiO2 from an oxalic-acid hydrothermal leachate of vanadium slag”. The authors reported that they had made changes in their manuscript, which took into account all my comments and suggestions.
Although the quality of the manuscript has improved, I still think that figures 7 and 8 should be corrected. The font is relatively small. Perhaps enlarge each and show one below another.
I have no additional objections. The work is interesting, and I am sure it would interest the readers of the Metals—minor revision.
Author Response
Comment 1: Although the quality of the manuscript has improved, I still think that figures 7 and 8 should be corrected. The font is relatively small. Perhaps enlarge each and show one below another.
Authors’ Response: Thanks for your suggestions. The font in Figure 7 and 8 was enlarged.
Reviewer 2 Report
I also recommend to remove "optimized" from the title and "optimization" from the manuscript. I accept the rest responses to my review.
Author Response
Comment 1: I also recommend to remove "optimized" from the title and "optimization" from the manuscript.
Authors’ Response: Sorry for my careless. In the new revised manuscript, I have removed it.
