Effect of Sodium Metabisulfite on Selective Flotation of Chalcopyrite and Molybdenite

Round 1

Reviewer 1 Report

In this paper, MBS was used to separate molybdenite and chalcopyrite as a depressant. The paper was organized well and discussed in detail. I recommend that the paper could be published after some minor revisions.

1. In introduction, suggest to add a reference for (Wills 27 and Napier-Munn, 2006).
2. Which size do you use in the flotation tests? < 38μm? Please make sure.
3. Why did you use KOH to adjust pH? NaOH will be better and cheaper.
4. In Table 1, the grade of Cu and Fe is greater than its theoretical grade? Please point its component.
5. Did the authors consider different ratios of these two minerals in the flotation separation?
6. There are some small errors in the text, please read that carefully and revise.
7. In Fig. 3d, where was amyl xanthate from?
8. What does Newton efficiency mean? Please give the explanation in the beginning or give its calculation formula.
9. The Abstract and Conclusion should be more concise and accurate.

Author Response

thanks for your comment. I have revised and answered as attached reply and manuscript. please confirm. thanks for everything.

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear authors,

In your paper, you describe the selective flotation of chalcopyrite and molybdenite with the addition of sodium metabisulfite (MBS) as a chalcopyrite depressant. Based on the results of microflotation of high purity minerals chalcopyrite and molybdenite, you claim that MBS treatment can depress chalcopyrite while molybdenite can recover as a float. I agree, good results were obtained which were confirmed by analyzes.

I think the following should be done:

State in the discussion: „In mixed mineral flotation, as the MBS concentration increased, the recovery of chalcopyrite decreased significantly. On the other hand, the recovery of molybdenite remained higher under same  conditions, although there was a slight decrease. This result shows a similar trend to the recovery of chalcopyrite and molybdenite in the single mineral flotation. The Newton efficiency increased with increasing MBS concentration and turned to decrease at 5 mM MBS. This might be due to the fact the recovery of chalcopyrite was sufficiently depressed at 1 mM MBS and recovery of molybdenite decreased gradually with increasing MBS concentration“. 47.7 % was obtained at 1 mM MBS. These flotation results indicated the possibility of selective flotation of chalcopyrite and molybdenite with MBS addition.

All right, it can be. Discuss in a few sentences the following: The recovery of molybdate in the mixture is higher compared to chalcopyrite, but there is still a slight decrease. What would happen with an increase in MBS concentration?

Please note that MBS is a reducing agent, not an oxidizing agent. You need to correct that.

What about MBS in the aquatic environment? Is NaHSO₃ not formed?

       Na₂S₂O₅  + H₂O   =   2 NaHSO₃

Where do sulfates come from and in what quantities? Maybe from oxidized NaHSO₃, which was formed and oxidized itself.

Discuss this and send me your thoughts.

 

With respect

Author Response

thanks for your comment. I have revised and answered as attached reply and manuscript. please confirm. thanks for everything.

Author Response File: Author Response.pdf

Reviewer 3 Report

Dear Authors,

The effect of sodium metabisulfite on the selective flotation of sulphide minerals has been studied so far and the given results in this paper did not show novelty. The interpretation of the results was mainly based on literature and it was common and basic, so the key points were missing. The main concern with this manuscript is English writing. It heavily suffers from incorrect English writing. This makes understanding and reviewing the manuscript very difficult.

The reviewer thinks that the following problems must be solved before considering the publication of the manuscript (reject and resubmit).

• The introduction part must be rewritten. The introduction should be a highly systemized review of the work that has been done. The contents of introduction lack the linkage between a review of the background and the objectives of this research.
• Please revise line 143 “This result indicated that the untreated chalcopyrite was not affected by MBS and had a single peak was derived from chalcopyrite”. You shouldn’t have explained this result before 5mM MBS treatment.
• For the language, there are some grammatical errors throughout the paper. Therefore, the language should be improved. For example:
• Please revise line 152 “This result indicates that the MBS treatment cover chalcopyrite surface these oxide, sulphate and hydroxide product, it makes chalcopyrite surface hydrophilic”. This sentence is not clear.
• Please revise line 206.
• Please revise line 202. …. then chalcopyrite surface covered hydrophilic sulfate and hydroxide product. It should be “is covered by” …
• Please provide some references for line 162.
• Please provide the Newton efficiency Eq. in the text.
• Why did chalcopyrite recovery increase with increasing kerosene or diesel oil?
• Please explain why with the addition of 100 mg/L diesel oil, molybdenite recovery started to decrease.
• Did you do any MBS adsorption study onto mineral surfaces at various conditions (concentration of MBS remaining in the solution after treatment). If yes, please provide them in the manuscript.
• How do the contact angles of chalcopyrite and molybdenite change with increasing concentration of MBS?
• Please provide the results of these tests in the text: MBS = 0 and 100 mg/L diesel oil and MBS =0 and 200 mg/L kerosene. Compare this information with your results.

Author Response

thanks for your comment. I have revised and answered as attached reply and manuscript. please confirm. thanks for everything.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Dear authors

Thank you for changing the paper to accommodate some of my concerns. The paper contains useful material and valid results, and there is, therefore, a recommendation to publish it in your Journal.