Influence of the Impeller Diameter and Off-Bottom Clearance on the Flow Velocity Distribution Characteristics Near the Bottom inside a Flotation Machine

Round 1

Reviewer 1 Report

Dear authors of the manuscript,

Corrections are well done.

Best regards and good health,

Author Response

 

Thank you very much for your acceptance for all the corrections done to our manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript presents significant improvements and should be accepted after checking a minor comment:

In: "In the present paper, flow velocities of fluid near the bottom of the KYF flotation machine are improved when the off-bottom impeller clearance is increased from 24 mm to 28, 32 and 36 mm. Furthermore, its increase will inevitably expand the circulation range of the bottom fluid, which will favour bypass flows [37]. Thus it can also be inferred that the larger impeller off-bottom clearance is beneficial to reduce the residence time and improve the solids suspension in some degree.", the last two sentences are a bit unclear. I interpret that bypass flows and shorter residence times are positive for the flotation process. Please reword.

Author Response

Thank you very much for your approval of the revised version of our manuscript.

Regarding to your comment about the last two sentences in the fourth paragraph of Section 3.5, we revised the last two sentences and the previous sentence as " In the present investigation, flow velocities of fluid near the bottom of the KYF flotation machine are improved when the impeller off-bottom clearance is increased from 24 mm to larger values, so shorter residence times can also be realized by larger impeller off-bottom clearance. Furthermore, increasing the impeller off-bottom clearance will expand the circulation range of the bottom fluid inevitably so as to favour bypass flows ^[43]. Therefore it can be inferred that larger impeller off-bottom clearance is positive to flotation process in terms of reducing the residence time and favouring bypass flows. "

     We marked the revised sentences in dark red. The serial number of reference 37  was adjusted to 43, because we enriched several new references regarding to the LDA technique according to the suggestions of another reviewer of our manuscript.

Author Response File: Author Response.pdf

Reviewer 3 Report

Please find attached my comments and suggestions.

Comments for author File: Comments.pdf

Author Response

Thank you very much for your comments on our manuscript. We have revised it carefully, please review it again in the current version. All the changes are explained in the cover letter. 

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The authors have satisfactorily addressed all comments from my previous review. The manuscript should be accepted for publication.

Thank you

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Dear authors,

I have no remarks and think the present Article can be accepted in the present state.

Reviewer 2 Report

Dear authors,

Your manuscript is a scientific research work on defining the optimal working conditions of a flotation machine. In the experimental part, the fluid flow velocities near the bottom of the laboratory KIF flotation machine were determined. This was done to examine the influence of the diameter of the impeller and the clearance of the lower part of the rotor on the flow. speed distribution. Based on the experimental results, flow patterns at different impeller parameters were analyzed. You have proved that the suspension of solid particles in a flotation machine depends on the flow characteristics at the gap between the bottom of the impeller and the bottom of the flotation tank.

I would suggest the following:
1. Verification of a mathematical model with a simulated technological flotation procedure.
2. Cumulative curve of granulometric composition of the tested suspension.
3. Percentage of material suspension and viscosity
4. Optimization of the procedure with checking the air flow and process time.

With respect

 

Reviewer 3 Report

This paper studies the influence of impeller diameter and off-bottom clearance on the flow patterns of a flotation machine. The paper requires some improvements before publication.

Major comments:

The background presented in the introduction seems appropriate. However, it may be enriched by industrial evidence showing that mixing or solid suspension are still a concern in flotation. This point would potentially improve the contextualization of the proposed study in the short and long term. In other words, if the problem is not observed industrially, does it really matter?

The authors studied the effect of impeller diameter and depth on the fluid patterns. What would be the effect of changing the impeller diameter or depth on the residence time and residence time distribution? For example, wider impellers will decrease the residence time at some extent. Higher distances from the bottom will favour bypass flows. Please discuss and support by the respective information available from literature.

Discussions about Figs 8 to 10 seem appropriate for mechanical or fluid engineering. What are the main results/conclusions for mineral processors?

What is the particle size of the tracers? Is it realistic? Why was that particle size chosen?

 

Minor comments

Do you mean froth flotation instead of foam flotation?

Please replace desorption by detachment.

Is it possible to use a scalable parameter instead of impeller diameter? For example, ‘impeller diameter’/’cell diameter’.

What does it define the different radial position domains in Figs. 6 and 7?

When reporting maximum velocities, I think it would be clearer to present the maxima for some norm.