Spent Lithium-Ion Battery Recycling Using Flotation Technology: Effect of Material Heterogeneity on Separation Performance
, Barbara Etschmann 2, Joël Brugger 2, Warren Bruckard 3, Jorge Menacho 4, Lorena Molina 5 and Andrew Hoadley 1,*Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis manuscript is novel in that it investigates the flotation separation of graphite and cathode active materials from black mass, compares the difference in flotation effectiveness between a single type of spent lithium-ion battery and a mixed-type battery, and introduces tools such as entrainment degree and flotation kinetics. The results are understandable but should be improved for publication. Some suggestions and corrections in your work will make your manuscript more attractive and suitable for publication in the journal "Processes":
In the abstract, the authors mention the grade of cathode active material in the pulp product (tailings). However, further explanation about the grade and recovery of cathode active materials in the pulp product is not provided in the section of results. Please expand on this section.
L163. According to the Supplementary Material and Figure 2, N2 atmosphere is used in this roasting process. Would it be more accurate to use the term “pyrolysis” rather than “roasting”?
L235-L236. Should Rc refer to the recovery of cathode active material in the flotation concentrate (froth product) or the recovery of cathode active material in the pulp product? This should be clarified to avoid confusion.
Figure 6. It may be difficult to distinguish between NMC particles and graphite by SEM alone, especially without the combination of EDS/WDS. Therefore, please include SEM images of the reference material, such as pure NMC particles and pure graphite samples, to make it easier for the reader.
Figure 7 and Figure 10. Is the graph depicting the cumulative recovery of cathode active material in the froth product rather than the cumulative recovery of cathode active material in the pulp product (tailings)? Please clarify this in the captions and the main text to avoid any misunderstanding.
Increasing the number of cleaner stages might significantly reduce the recovery rate of graphite. Therefore, are there any alternative methods?
Author Response
See response letter in the document attached.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript discusses the recovery of spent lithium-ion batteries using flotation technology, with a focus on the influence of material heterogeneity on separation performance. The study evaluates two recovery scenarios: one involving a single cathode chemical composition, and the other involving a mixed cathode chemical composition from industrial recycling operations in Australia. The results demonstrate good performance in both scenarios, with high recovery rates and grades of the anode in the final concentrate. The manuscript highlights the importance of preprocessing prior to the flotation process and confirms flotation as a viable technology for the separation of battery materials. The study is well-founded and reasonable, with the following minor revisions to be considered for acceptance:
1. The paper reads more like an experimental report, and the Results and Discussion section should focus on ensuring logical coherence between sections rather than merely describing the content of figures.
2. The Conclusion section is overly verbose and should be further refined for conciseness.
3. Attention should be given to the organization of figures, for example, Figure 6 should be more orderly arranged and the figures and captions should not be separated.
Comments on the Quality of English Language
No
Author Response
See response letter in the document attached.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsNearly all the shortcomings pointed out in the first round of revisions have been adequately addressed. The manuscript has been greatly improved. Thanks!
The only remaining suggestion pertains to my first comment. It would be beneficial to include a brief description of the two grades, 93.9% and 87.1%, mentioned in the abstract within the manuscript.
I recommend accepting the manuscript.
Author Response
Please find attached the response document.
Author Response File: Author Response.pdf
