Numerical Simulation of Cathode Nodule Local Effects

Round 1

Reviewer 1 Report

The overall mark on the manuscript quality is above average. I have made review report and attached this file as a part of this letter. Authors should note that major of the errors made are technical, so in my opinion that you will finish with recommendations very quickly.

Comments for author File: Comments.pdf

I haven't found any serious errors regarding English quality, but there are plenty of text duplicates that may be found throughout the manuscript (all those comments are given by review report).

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The transport phenomena of ions is important matter for non-ferrous metallurgy. Especially that electrowinning and electrorefining processes are key for cuprum industry. Therefore presented topic is worthy and results give additional insight to classical metallurgical process.

1. The sketch of numerical model is not clear. It should be improved by adding dimensions of electrodes and exact location of nodule. Moreover to this sketch, boundary conditions used in the simulation have to be add. Especially that inflow/outflow boundary conditions for electrolyte is not plainly describe.
2. Data on grid solutions near the wall of electrodes are essential i. e. dimensions of elements, degree of denseness.
3. What number of elements consist global numerical grid? What type of element was used in the grid?
4. What was the flow rate of electrolyte via cell?
5. What type of software Authors used?
6. What means cathodic symmetry factor? Why two values of CSF include table 1.
7. Figure 3 not presents sketch (b). Additionally the caption of figure 3 in not clear and should be rebuilt.
8. Caption of figure 8 and letter signs in the figures include mistakes. Please improve.
9. Section 2.2 should be change to numerical model.

Author Response

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Reviewer 3 Report

The article discusses the importance of nodule growth in the copper electrorefining process, highlighting its impact on current efficiency and product quality. Using 3D Finite Element Method (FEM) models combining tertiary current distribution and fluid flow, the details of columnar nodule growth are investigated. It is observed that active nodules significantly affect fluid flow due to electrochemical reaction, which may be a reason for the formation of clusters of small nodules on the cathode. Additionally, it is noted that the local current density on the nodule surface is uneven due to the influence of multiple factors, resulting in asymmetric growth of the nodules, with the upper parts growing faster than the lower parts. This study provides a deeper understanding of the underlying mechanisms of nodule growth in the copper electrorefining process.

What criteria were considered in determining the dimensions and placement of the nodule within the computational model of the electrolytic cell? Additionally, could you elaborate on the specific techniques employed for mesh optimization, particularly focusing on the front end of the nodule?

What specific methods or techniques were employed to visualize and analyze the flow field distribution during normal electrolysis without nodules, as shown in Figure 2a?

What specific techniques or methodologies were employed to analyze and quantify the disturbance in electrolyte flow caused by the reduction reaction occurring on the surface of the nodule? Additionally, how were the findings from the comparisons between Figures 2c and 2d utilized to assess the influence of nodule length on the electrolyte flow characteristics?

Author Response

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Reviewer 4 Report

The authors evaluated the cathode anode reaction mechanism in the copper electrolytic cell by numerical simulations. The work is of great interest to researchers and industry and the manuscript is well written. As a reviewer, I recommend the acceptance of the manuscript after the following minor revisions:

- Line 41. It is not appropriate to use "etc" in scientific texts.

 - Line 109: "Where, is the local local overvoltage at the electrode interface, defined as:". Please, revise this sentence. The word "local" is repeated and the term "n" is not shown.

- Table 1 - Please, revise "Exchange current densityentry"

- Line 357 - "This hindrance is more pronounced in the D2 local. Figure 8 We selected YZ cross-sections of 2mm, 10mm, and 22.5mm to represent locals 1, 2, and 3 respectively presents velocity streamlines an... " Please, revise this sentence. 

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Dear Authors,

Thank You very much for your responses.

Still it is not clear what means pressure boundary condition using for outlet. Sketch 1b no explain boundary conditions for considered numerical model. Due to lack of forced convection, did Authors use 0 m/s of initial value of electrolyte velocity at inlet boundary condition? If Yes please add explanation to text of work.

Regards

Author Response

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Author Response File: Author Response.pdf