Precious Metals Recovery Process from Electronic Boards: Case Study of a Non-Profit Organization (QC, Canada)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript deals with literature survey and economic assessment of the recovery of precious metals from electronic waste for the case of non-profit organization, which helps to employ people with mental health problems. In my opinion, the manuscript contains relevant references, good summary and valid economic evaluation. The content is also interesting, so I recommend the publication after minor revision.

 

I highlighted some recommendations, questions and comments for authors according to the manuscript:

Line 120. Table 1. Chemical formulas of leaching reagents in the first column of the table should be added.

Line 238. Generally, pyrometallurgical methods are the first stage of a treatment flowsheet for the recovery of valuable elements. In any case, precious metals should be recovered and selectively separated from the obtained enriched products (for example, slag or metal) using other methods (usually hydrometallurgical ones). Thus, an additional treatment stage is needed. This fact can be added as a disadvantage in the text and even in Table 5.

Line 243. Why did you decide that the recovery degree over 80% is sufficient? Why didn’t you choose 85, 90, 99%? Please, give a reference or explain it in the text.

Line 278-279. You choose the hydrometallurgical approach as the most appropriate. OK. Could you discuss based on table 1, which leaching agent would be suitable for your case? On the contrary, which leaching agent would be unsuitable?

Author Response

Dear Reviewer, 

Thank you for your valuable feedback. We appreciate your time and effort in reviewing our work. 

Our responses to your comments are in red below, and the corrections made to the article can be found in the attached file: 

•  "Line 120. Table 1. Chemical formulas of leaching reagents in the first column of the table should be added."

Line 120 now includes the formulas of the reagents or ions in Table 1.

• "Line 238. Generally, pyrometallurgical methods are the first stage of a treatment flowsheet for the recovery of valuable elements. In any case, precious metals should be recovered and selectively separated from the obtained enriched products (for example, slag or metal) using other methods (usually hydrometallurgical ones). Thus, an additional treatment stage is needed. This fact can be added as a disadvantage in the text and even in Table 5."

Tables 2 and 5 now include additional treatment stage information. The discussion on the choice of process has been clarified for precision (lines 311 to 313). 

• "Line 243. Why did you decide that the recovery degree over 80% is sufficient? Why didn’t you choose 85, 90, 99%? Please, give a reference or explain it in the text."

Details on the 80% recovery rate have been added (see lines 254 to 260).

• "Line 278-279. You choose the hydrometallurgical approach as the most appropriate. OK. Could you discuss based on table 1, which leaching agent would be suitable for your case? On the contrary, which leaching agent would be unsuitable?"

Lines 278-279: The choice of reagent is now discussed in lines 319-326.

We hope these revisions meet your expectations.

Thank you in advance.

Sincerely,

 Caroline Blais | Ph. D student 

Department of Industrial Engineering| Quebec University in Trois-Rivières (UQTR)

www.uqtr.ca 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

 

Thanks for studying ways of recovering precious metals from old electronic devices. Hopefully, it will help to reduce pollution and to induce the creation of new companies with this task. Manuscript is well written and organized, and deserves being published in Sustainability journal in my opinion, after careful consideration of these comments:

 

1) It is recommended to avoid using references in the abstract: “Evaluated at 53.4 Mt in 2019, the amount of electronic waste that will be 15 produced by 2030 is estimated at 74 Mt [1]”.

2) At the case study, worker's safety should be included too, especially if they have mental health diseases and by-products are toxics for humans or telecom devices manual dismantling involves potential sharp pieces.

3) A mention about the purity of the metals recovered is suggested (at least in the case of study).

 

Minor comments:

4) Line 171: "MP" should have the "P" as a subscript, according to formula (1).

5) Table 3: "Data" is actually plural, it is recommended to avoid the term "datas".

6) Table 3: it is recommended to reorganize the notes of the table to be completely underneath the table, and B total values closer to the rest of the values.

7) It is suggested to specify that in Figure 1 it is represented the "total economic value B", since "economic distribution" could be misunderstood.

 

Best regards.

Comments on the Quality of English Language

Table 3: "Data" is actually plural, it is recommended to avoid the term "datas".

Author Response

Dear Reviewer, 

Thank you for your valuable feedback. We appreciate your time and effort in reviewing our work. 

Our responses to your comments are in red below, and the corrections made to the article can be found in the attached file: 

1. " It is recommended to avoid using references in the abstract: “Evaluated at 53.4 Mt in 2019, the amount of electronic waste that will be 15 produced by 2030 is estimated at 74 Mt [1]”."

This sentence was removed as it was not essential for understanding the summary.

• "At the case study, worker's safety should be included too, especially if they have mental health diseases and by-products are toxics for humans or telecom devices manual dismantling involves potential sharp pieces."

Details on worker safety management have been added to lines 240 to 250.

• " A mention about the purity of the metals recovered is suggested (at least in the case of study)."

A mention concerning the metal purity has been added (lines 261-264).

•  "Line 171: "MP" should have the "P" as a subscript, according to formula (1)."

Line 171: Formatting of characters has been corrected.

• " Table 3: "Data" is actually plural, it is recommended to avoid the term "datas"."

Corrections have been made to the words 'Data' in the notes for Table 3.

• " Table 3: it is recommended to reorganize the notes of the table to be completely underneath the table, and B total values closer to the rest of the values."

The format of the notes in Table 3 has been modified.

• " It is suggested to specify that in Figure 1 it is represented the "total economic value B", since "economic distribution" could be misunderstood."

The title of Figure 1 has been modified.

 

We hope these revisions meet your expectations.

Thank you in advance.

Sincerely,

 Caroline Blais | Ph. D student 

Department of Industrial Engineering| Quebec University in Trois-Rivières (UQTR)

www.uqtr.ca 

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This manuscript reports on an effort to recover precious metals from end-of-life electronic telecommunication cards through a hydrometallurgical process, thereby hoping to create an environmentally friendly and cost-effective process for precious metal recovery. However, in my view, the following issues need to be addressed before consideration for publication.

1.       There are too few references used in the manuscript, too few references cited by the authors in the introduction for background, and no indication of the innovative nature of this work.

2.       The authors conclude with a reference to designing a new ecological and economic process to recycle precious metals to help more people struggling with mental health issues, but the reader cannot understand the cause and effect relationship.

3.       The formatting of the references in the text is highly problematic, with many not having page numbers.

4.       The authors do not explicitly point out the advantages of the hydrometallurgical process over the Pyrometallurgy and Biometallurgy processes in the paper, and in general, the innovative nature of this work, as well as the amount of work involved, leaves something to be desired.

Comments on the Quality of English Language

 Minor editing of English language required.

Author Response

Dear Reviewer, 

Thank you for your valuable feedback. We appreciate your time and effort in reviewing our work. 

Our responses to your comments are in red below, and the corrections made to the article can be found in the attached file: 

• " There are too few references used in the manuscript, too few references cited by the authors in the introduction for background, and no indication of the innovative nature of this work."

Clarified the purpose of the article in lines 44-47, and added references in the Introduction, Existing Processes, and Tables 1 and 2.

• " The authors conclude with a reference to designing a new ecological and economic process to recycle precious metals to help more people struggling with mental health issues, but the reader cannot understand the cause and effect relationship."

Edited text to clarify the idea (lines 331-335).

• "The formatting of the references in the text is highly problematic, with many not having page numbers."

We used bibliography software to update the references. Hope the data is complete and the format meets your expectations.

• "The authors do not explicitly point out the advantages of the hydrometallurgical process over the Pyrometallurgy and Biometallurgy processes in the paper, and in general, the innovative nature of this work, as well as the amount of work involved, leaves something to be desired."

We added clarifications to the discussion (lines 305 to 326).

We hope these revisions meet your expectations.

Thank you in advance.

Sincerely,

 Caroline Blais | Ph. D student 

Department of Industrial Engineering| Quebec University in Trois-Rivières (UQTR)

www.uqtr.ca 

Author Response File: Author Response.pdf