Melt Conditioned Direct Chill (MC-DC) Casting of AA-6111 Aluminium Alloy Formulated from Incinerator Bottom Ash (IBA)

Round 1

Reviewer 1 Report

In the case of equiaxed refined grain of DC-GR billets, could be useful if the size data are adjusted to a size distribution function with the corresponding average size and standard deviation and compare with the distribution function of the MC-DC billets. The authors say that “The position of the shearing device in the hot-top was placed at an optimised depth”. Using the word “optimised” suggest that a mathematical optimisation technique was implemented and the final position of the shearing device was obtained as a result of such technique. In this case, it is suggested replace the word “optimised” and use “the more appropriate position” (or some similar word that is not related with optimisation). The authors point out that the overall cooling rate is uniform in this system. This is probably due to a uniform global coefficient of heat transfer. In many cases, the heat transfer from the surface could have local coefficients of heat transfer –instead of a global coefficient- and if this is the case, over the surface could appear temperature gradients that ultimately influence the microstructure. This could generate a non-uniform microstructure. It is suggested check this aspect and be sure if the obtained microstructure of the billets is “uniform” or “more uniform”. Distribution function of grain size could help to solve this.

Author Response

Dear Reviewer,

Many thanks for reviewing our manuscript. We are grateful for your comments as they are very important for this study. Please see below, in red, our detailed response to your comments:

Comments and Suggestions for Authors

In the case of equiaxed refined grain of DC-GR billets, could be useful if the size data are adjusted to a size distribution function with the corresponding average size and standard deviation and compare with the distribution function of the MC-DC billets.

A- I agree with you, but we will use the grain size distribution graphs for DC-GR and MC-DC in our coming manuscript to discuss the effect of uniformity of grain size across the billets section on improving the mechanical properties of final product.

The authors say that “The position of the shearing device in the hot-top was placed at an optimised depth”. Using the word “optimised” suggest that a mathematical optimisation technique was implemented and the final position of the shearing device was obtained as a result of such technique. In this case, it is suggested replace the word “optimised” and use “the more appropriate position” (or some similar word that is not related with optimisation).

A- We have tested MC-DC casting by changing the position of the shearing devise until we got acceptable results. I have amended the manuscript by replacing optimized by appropriate.

The authors point out that the overall cooling rate is uniform in this system. This is probably due to a uniform global coefficient of heat transfer. In many cases, the heat transfer from the surface could have local coefficients of heat transfer –instead of a global coefficient- and if this is the case, over the surface could appear temperature gradients that ultimately influence the microstructure. This could generate a non-uniform microstructure. It is suggested check this aspect and be sure if the obtained microstructure of the billets is “uniform” or “more uniform”. Distribution function of grain size could help to solve this.

A- I agree with you 100%. The micrographs across the whole billet section showed uniform microstructure for MC-DC casting. These micrographs will be present in the forthcoming paper.

Reviewer 2 Report

The paper is well structured, and concerns a topic very actual and relevant.

Literature overview is good, and aims of the paper are well described.

The paper is certainly worth of publication.

I have three minor comments:

1) please check the structure of the text in lines 158 and 159,

2) quality of Fig. 4 should be improved

3) it should be better (lines 203 and 204) give some anticipation on the mechanical performance of the products achieved.

Author Response

Dear Reviewer,

Many thanks for reviewing our manuscript. We are grateful for your comments as they are very important for this study. Please see below, in red, our response to your comments:

Comments and Suggestions for Authors

The paper is well structured, and concerns a topic very actual and relevant.

Literature overview is good, and aims of the paper are well described.

The paper is certainly worth of publication.

I have three minor comments:

-please check the structure of the text in lines 158 and 159.

A- Done

-quality of Fig. 4 should be improved.

A- Done, I have changed the sharpness.

-It should be better (lines 203 and 204) give some anticipation on the mechanical performance of the products achieved.

A-Done

Reviewer 3 Report

The article entitled "Melt conditioned direct chill (MC-DC) casting of AA6111 aluminium alloy formulated from incinerator bottom ash (IBA)" is an interesting article about the utilization of aluminum obtained from incinerator bottom ash. Several questions might be improved:

Line 26: examples of materials to be recovered.

Abbreviations: there are several abbreviations that are not defined (BCAST, EMP).

Line 46: "techniques"

Sentence starting in Line 62: is the cost the only disadvantage or there are others?

Line 89: what is the composition of the process scrap?

Line 91: In what materials were the copper and magnesium levels adjusted? why?

Line 92: How did you calculate the liquidus temperature?

Section 3.1: How do you explain the low yield?

In metallurgy it is quite more common using the word "slag" instead of "dross"

Figures 5 and 6: You use letters in these figures, so it would be useful for the reader to have the letters also in the text (Example: sentence starting in line 176, what is the micrograph?

 

Author Response

Dear Reviewer,

Many thanks for reviewing our manuscript. We are grateful for your comments as they are very important for this study. Please see below, in red, our detailed response to your comments:

Comments and Suggestions for Authors

The article entitled "Melt conditioned direct chill (MC-DC) casting of AA6111 aluminium alloy formulated from incinerator bottom ash (IBA)" is an interesting article about the utilization of aluminum obtained from incinerator bottom ash. Several questions might be improved:

-Line 26: examples of materials to be recovered.

A- Done

-Abbreviations: there are several abbreviations that are not defined (BCAST, EMP).

A- Done

-Line 46: "techniques"

A- Done

-Sentence starting in Line 62: is the cost the only disadvantage or there are others?

A- There are many disadvantages such as contamination of the alloy, limitation of using grain refiner for cast alloy, interaction between grain refiner and solutes in the alloy, etc. I have amended the manuscript for that.

Done

-Line 89: what is the composition of the process scrap?

A- Done

-Line 91: In what materials were the copper and magnesium levels adjusted? why?

A- AlCu40 master alloy and pure Mg were added to adjust the composition to match the target alloy AA-6111. Done

-Line 92: How did you calculate the liquidus temperature?

A- Done

-Section 3.1: How do you explain the low yield?

A- We have mentioned in line 140-145 to the reason for low yield. There was too much dross or slug due to oxidation.

-In metallurgy it is quite more common using the word "slag" instead of "dross"

A- You are right, but w use dross in all our publications in BCAST.

-Figures 5 and 6: You use letters in these figures, so it would be useful for the reader to have the letters also in the text (Example: sentence starting in line 176, what is the micrograph?

A- In line 176, it was general discussion about microstructure of DC casting, not related to any micrograph in the manuscript. But I have amended the manuscript and used the micrograph number with the letter.