α-Amino Phosphonic Acid as the Oxidized Ore Collector: Flexible Intra-Molecular Proton Transfer Providing an Improved Flotation Efficiency
Round 1
Reviewer 1 Report
In this study, APA (aminooctyl phosphonic acid) has been used as a new collector and alternative to OPA (octylphosphonic acid) for flotaton of ilmenite. Microflotation experiments, zeta-potential, adsorption, FTIR and XPS measurements were performed to explain the adsorption mechanism of APA on ilmenite.
The paper is well structured and the results are clearly presented. English of the paper is at a high standard and does not require major editing. I think the paper can be accepted for publication in its present form.
Author Response
Thanks.
Reviewer 2 Report
the paper deals with an interesting topic and I invite you to read my comments attached below
Comments for author File: 
Comments.pdf
Author Response
- The authors provide various details necessary to understand the description of the materials used during the preparation of their article. (Please see page 3, raw 55-74). However, despite the fact that they presented the chemical composition of the samples of ilmenite and titanaugite, they neither refer to the analytical technique nor to apparatus used to carry out the analyses that enabled them to obtain what they present as results from the samples characterization. I recommend that they provide these analytical details for more credibility of their claims.
Response: Many thanks for the reviewer’s comment. We have added the model and manufacturer of the instrument used to detect ilmenite and titanaugite.
- Please see page 3, raw 82-83: “(4) collecting floated particles as flotation concentrate for 3 min and un-floated particles as flotation ???;………….” I have the impression that this sentence is incomplete and deserves to be corrected at the end to write it as follows: "4) collecting floated particles as flotation concentrate for 3 min and unfloated particles as flotation’s tailing".
Response: Many thanks for the reviewer’s comment. “(4) collecting floated particles as flotation concentrate for 3 min and un-floated particles as flotation ???;………….”has been changed to "4) collecting floated particles as flotation concentrate for 3 min and unfloated particles as flotation’s tailing".
- Please see page 5, raw 126-128: “Finally, the prepared samples were ground and mixed with spectral grade KBr, compressed into tablets for measurement.” I suggest that a small change be introduced in this sentence: “Finally, the prepared samples were ground and mixed with spectrographic grade KBr, compressed into tablets for measurement.”
Response: Many thanks for the reviewer’s comment. “Finally, the prepared samples were ground and mixed with spectral grade KBr, compressed into tablets for measurement.” has been changed to “Finally, the prepared samples were ground and mixed with spectrographic grade KBr, compressed into tablets for measurement.”.
- I note a thorough interpretation by the authors of the results provided by the various tests of flotation of individual minerals by varying the pH of the pulp and the concentration of each of the collectors used. The conclusions reached are relevant because they highlight the superiority of APA over OPA in terms of flotation efficiency. However, I recommend that they support their explanations to interpret the phenomena observed with more data from the literature.
Response: Many thanks for the reviewer’s comment. More data from the paper have been added to explain the experimental phenomenon.
Author Response File: 
Author Response.docx
Reviewer 3 Report
This is a valuable survey on exploring the applicability of an AP acid type as a selective collector for ilmenite. The experimental observations have been well supported with instrumental analyses and discussions follow a rational reasoning. The paper can contribute to the current knowledge of the issue and recommended for publication. However, esteemed authors are suggested to make up their paper with the following comments:
1. Authors may rethink about the title. This "α-amino providing the unexpected flotation efficiency" is not professional!
2. Introduction needs a significant redesign. Tale 1 is interesting but you should redecorate the structure of introduction by providing a deep literature review by exploring the relevant works, presenting their key findings, challenging the reported results and finally, highlighting the novelty of your own work.
3. Please provide more clarifications on the nonlinear effect of pH on recovery observed in Figs. 3, 4 and 5.
Good luck,
Author Response
- Authors may rethink about the title. This "α-amino providing the unexpected flotation efficiency" is not professional!
Response: Many thanks for the reviewer’s comment. The title of the article has been revised to “α-Amino phosphonic acid as the oxidized ore collector: flexible intra-molecular proton transfer providing an improved flota-tion efficiency”.
- Introduction needs a significant redesign. Tale 1 is interesting but you should redecorate the structure of introduction by providing a deep literature review by exploring the relevant works, presenting their key findings, challenging the reported results and finally, highlighting the novelty of your own work.
Response: Many thanks for the reviewer’s comment. Introduction has been reimagined and revised.
- Please provide more clarifications on the nonlinear effect of pH on recovery observed in Figs. 3, 4 and 5.
Response: Many thanks for the reviewer’s comment. We have further illustrated the nonlinear effect of pH on recovery in Figs. 3,4 and 5.
Author Response File: Author Response.docx
