Determination of the Li Distribution in Synthetic Recycling Slag with SIMS

Round 1

Reviewer 1 Report

The mineralogical study for lithium distribution in slag is important for lithium recycling from pyrometallurgical treatment of LIBs.

 

However, please check and add the following parts,

 

p.2, line 46,  

Please check the composition of (Li(2x))Mn2+(1-x)1+x)(Al(2-z),Mn3+(z))O4.

 

Line 74,

Please write the equipment type and company in the used (EPMA).

 

p.3, line 100

 

In Table 1, please show what parts are LiAl and LiAlO2.

 

In all references, please write the names with reference number.

Line 125,  

・・・given in [10]. 　Please write the name ・・・given in 〇〇　[10].

Line 137

・・・were 〇〇　([5], [6])

 

Line140-141

Please check the chemical composition again. Li1-xMgy(Al)・・・・、or (Li1-x(Mn・・・)

 

Line 143

Please indicate the meaning of ?.

 

Line 146, 187

Please check the chemical formula of “ (Li(2x)Mn2+(1-x)1+x)”・・・.

 

In Figure 2, please write which is (l) and (r).

Also indicate the meanings of numbers and + for 6 Li+ and 44 Ca+.

 

p.6, line 212

Please show the image number in Figure 1.

 

p.8 line 250

What is (ss, (Mn)))?

 

In Table 1, the left side Li content is larger than right side, however, in the chemical composition Li0.94 in the left is smaller than Li0.95 in the right. Please explain it.

 

To investigate spinel, please describe the XRD results.

 

Please describe the possibility of recycle of lithium by observing the micro structure for slag if it is possible.

Author Response

Dear Reviewer

This letter contains the description of the requested revisions of our manuscript:

 Determination of the Li-distribution in synthetic recycling slag with SIMS

By Thomas Schirmer (corresponding author),  Michael Wahl, Wolfgang Bock and Michael Kopnarski

First of all we would like to thank you for elaborately reviewing our paper.

This was very helpful and we learned a lot in terms to improve our future work. We hope the revision is according to your suggestions and our manuscript can be moved to the next processing step.

Thank you for your time and consideration.

Sincerely, Thomas Schirmer

The following text explanations how we responded to your comments on the revised version

Info: The authors apologize for the limited detailed argumentation. The article was ment to be a short communication to present first results of the Li-distribution in phases of pyrometallurgical slag. Detailed investigations will be carried out in the scope of apriority programme of the german research foundation (DFG)

The mineralogical study for lithium distribution in slag is important for lithium recycling from pyrometallurgical treatment of LIBs.

However, please check and add the following parts, 

p.2, line 46,  

Please check the composition of (Li(2x))Mn2+(1-x)1+x)(Al(2-z),Mn3+(z))O4.

Info: Checked using x and y --> OK 

Line 74,

Please write the equipment type and company in the used (EPMA).

Info: Mentioned in Line 79 - 81

p.3, line 100

Info: This error was not recognized in the downloaded document but maybe due to field function of word. The functions are now removed

In Table 1, please show what parts are LiAl and LiAlO2.

 Changed: LiAl = LiAlO₂ The abbrev. is defined later in chapt. 3.1.

In all references, please write the names with reference number.

Changed

Line 125,  

・・・given in [10]. 　Please write the name ・・・given in 〇〇　[10].

Changed

Line 137

・・・were 〇〇　([5], [6])

 Changed

Line140-141

Please check the chemical composition again. Li1-xMgy(Al)・・・・、or (Li1-x(Mn・・・)

Info: Checked using x and y -à OK 

Line 143

Please indicate the meaning of ?.

 Changed (?: Plausible but to be  verified)

Line 146, 187

Please check the chemical formula of “ (Li(2x)Mn2+(1-x)1+x)”・・・.

 Info: Checked using x and y -à OK 

In Figure 2, please write which is (l) and (r).

Changed

Also indicate the meanings of numbers and + for 6 Li+ and 44 Ca+.

Changed

p.6, line 212

Please show the image number in Figure 1.

changed

p.8 line 250

What is (ss, (Mn)))?

 changed….contains Ca-alumosilicate (MCAS with Mn),….

In Table 1, the left side Li content is larger than right side, however, in the chemical composition Li0.94 in the left is smaller than Li0.95 in the right. Please explain it.

Info: There was a calculation error of a transcription error in the calculations. Using the values as stated in the table the correlation of stoichiometry and calculated Li-concentration is plausible.

Changed: The distinct deviation of the measured and calculated Si values (25.01 and 22.69) cannot be explained at the moment.

Changed:

To investigate spinel, please describe the XRD results.

 Changed: Text added: The description of the XRD results is beyond the scope of the article being classified as short communication. A detailed description of the XRD results of the same sample materials is recently published by Schirmer et al. [] and Wittkowski et al. []

Please describe the possibility of recycle of lithium by observing the micro structure for slag if it is possible.

Info: This is currently scope of an priority programme of the german research foundation (DFG)

 

 

 

 

Reviewer 2 Report

The authors thoroughly analyzed the synthetic slag using EPMA and SIMS to reveal the spatial distribution of the constituent elements, and the SIMS images provided good visualization of the distribution of the elements in different crystalline phases.
On the other hand, the scientific results are not so clear-cut: conclusions about usefulness of combining several analytical methods, such as EPMA and SIMS, are rather stale (P.11, L.359 – 370).

The beautiful SIMS images show the spatial distribution of the constituent elements, but the lack of explanation about the images does not effectively demonstrate the importance of the images.
The image fields of the SIMS are not always related to Figure 1, and the reviewer does not necessarily understand what the authors are discussing.

For example, Figure 3 shows "Detailed element distribution image of dendritic LiAl-crystal". However, there is no dendritic morphology in the image. The text about Figure 3 states "A first ROI (Figure 1, red square in image 2) concentrates on a detailed view of a dendritic LiAl crystal with high signal of Li and Al (Figure 3)" (P. 6, L. 212-213). However, the images are not numbered in Figure 1.
By carefully comparing the morphology, the reviewer finally understood that Figure 3 corresponded to the square area in the upper center image in Figure 1, but was confused by the red square area in the lower left image.

The reviewer recommends Major revision. The manuscript should be completely reconstructed to clearly explain the results and achievement of this work. Otherwise, the revised manuscript may be rejected.

Author Response

Dear Reviewer,

This letter contains the description of the requested revisions of our manuscript:

 Determination of the Li-distribution in synthetic recycling slag with SIMS

By Thomas Schirmer (corresponding author),  Michael Wahl, Wolfgang Bock and Michael Kopnarski

First of all we would like to thank you for elaborately reviewing our paper.

This was very helpful and we learned a lot in terms to improve our future work. We hope the revision is according to your suggestions and our manuscript can be moved to the next processing step.

Thank you for your time and consideration.

Sincerely, Thomas Schirmer

The following text explanations how we responded to your comments on the revised version.

The authors thoroughly analyzed the synthetic slag using EPMA and SIMS to reveal the spatial distribution of the constituent elements, and the SIMS images provided good visualization of the distribution of the elements in different crystalline phases.
On the other hand, the scientific results are not so clear-cut: conclusions about usefulness of combining several analytical methods, such as EPMA and SIMS, are rather stale (P.11, L.359 – 370).

Info: The authors apologize for the limited detailed argumentation. The article was ment to be a short communication to present first results of the Li-distribution in phases of pyrometallurgical slag. Detailed investigations will be carried out in the scope of a priority programme of the german research foundation (DFG)

The beautiful SIMS images show the spatial distribution of the constituent elements, but the lack of explanation about the images does not effectively demonstrate the importance of the images.
The image fields of the SIMS are not always related to Figure 1, and the reviewer does not necessarily understand what the authors are discussing.

For example, Figure 3 shows "Detailed element distribution image of dendritic LiAl-crystal". However, there is no dendritic morphology in the image.

Changed: Skeleton crystallizates(s)

The text about Figure 3 states "A first ROI (Figure 1, red square in image 2) concentrates on a detailed view of a dendritic LiAl crystal with high signal of Li and Al (Figure 3)" (P. 6, L. 212-213). However, the images are not numbered in Figure 1.

Changed: Numbering of image 1

By carefully comparing the morphology, the reviewer finally understood that Figure 3 corresponded to the square area in the upper center image in Figure 1, but was confused by the red square area in the lower left image.

Changed: the red square is now correlated to the SIMS pattern

The reviewer recommends Major revision. The manuscript should be completely reconstructed to clearly explain the results and achievement of this work. Otherwise, the revised manuscript may be rejected.

Changed: Substantial changes through the input of the other three reviewers

 

Reviewer 3 Report

Dear Authors and Editors,

The paper is worth publishing after some corrections.

Please see the comments below.

• Numbering problems, e.g. the first section of 2 is 3.1 (should be 2.1).
• Section "3.1" needs to include at least the slag composition. It only takes 1 sentence, but makes the paper understandable and standalone, without the need to peruse the internet for references.
• Line 100: "error! reference source not found".
• Table 1: if measurements are done as oxides, why not represent everything as oxides (Al2O3, MgO, TiO2, ...) rather than elements?
• The authors may need to state that the technique of Li evaluation may fail when the concentrations of elements with variable oxidation states (FeO/Fe2O3, MnO/Mn2O3) are high. Then, there are two unknowns (Li and O) that may contribute to the difference between 100% and observed total.
• Line 116: how LMIG abbreviation can be expanded?
• Line 153: there are compounds in the Li2O-Al2O3 system between Al2O3 and LiAlO2, i.e. LiAl5O8 and LiAl11O17 - other "possible candidates".
• Line 172: what means "coordination positions [4] and [8]"?
• Line 174: rankinite is not a melilite endmember, because Ca is not listed on the second sublattice.
• Line 177: these endmembers may be not enough to define melilite, because none of them has Li on the second sublattice.
• Line 183: unclear what kind of modelling is mandatory, since the spinel can be expressed with three endmembers: MgAl2O4, LiAl5O8 and Al2O3 to a high accuracy.
• Fig.3-6 can be much improved if the phases are labelled. For example, the 8th free square can be used for a sketch of the figure with manually drawn lines and labelled phases.
• Line 251: if Mn in distributed to all phases, it should not be because of its high concentration - the ratios of concentrations are constant in a wide range according to Henry's law. Probably the same for Na and K in line 317.
• Line 252-253: unclear sentence starting with "The ELAS(Mn)..."
• Line 331: why "crystallization of spinel stopped in an earlier stage" - earlier than what?

Grammar/terminology issues:

Line 30, 288: "pyrometallurgical" should not have a space

Line 148: phases

Line 153: minor component

Line 204: an alkali

Line 208: "monolithic" may be better to name "homogeneous"

Line 254: phase

Line 308: Whether

Line 323: a second

Line 326: solid (not capital)

Author Response

Dear Reviewer,

This letter contains the description of the requested revisions of our manuscript:

 Determination of the Li-distribution in synthetic recycling slag with SIMS

By Thomas Schirmer (corresponding author),  Michael Wahl, Wolfgang Bock and Michael Kopnarski

First of all we would like to thank you for elaborately reviewing our paper.

This was very helpful and we learned a lot in terms to improve our future work. We hope the revision is according to your suggestions and our manuscript can be moved to the next processing step.

Thank you for your time and consideration.

Sincerely, Thomas Schirmer

The following text explanations how we responded to your comments on the revised version

Info: The authors apologize for the limited detailed argumentation and . The article was ment to be a short communication to present first results of the Li-distribution in phases of pyrometallurgical slag. Detailed investigations will be carried out in the scope a priority programme of the german research foundation (DFG)

• Numbering problems, e.g. the first section of 2 is 3.1 (should be 2.1).
• Changed
• Section "3.1" needs to include at least the slag composition. It only takes 1 sentence, but makes the paper understandable and standalone, without the need to peruse the internet for references.
• Changed: The system of the synthetic slags contains Li₂O, MgO, Al₂O₃, SiO₂ and CaO and additionally MnOx in the case of the manganese containing material.
• Line 100: "error! reference source not found".
• Info: This error was not recognized in the downloaded document but maybe due to field function of word. The functions are now removed
• Table 1: if measurements are done as oxides, why not represent everything as oxides (Al2O3, MgO, TiO2, ...) rather than elements?
• Info: The data was presented as elements in this table because for the calculation of the stoichiometric formulas the element data is used (for comparison with Table 2)
• The authors may need to state that the technique of Li evaluation may fail when the concentrations of elements with variable oxidation states (FeO/Fe2O3, MnO/Mn2O3) are high. Then, there are two unknowns (Li and O) that may contribute to the difference between 100% and observed total.
• Info: Using the virtual compounds LiMnO₂ , Mn_0.5AlO₂  (1/2 galaxite spinel), and Mn_0.5MnO₂  (1/2 hausmannite) includes Li and MnII/MnIII. Using a non-linear Generalized Reduced Gradient (GRG2) solving method a solution can be computed.
• Line 116: how LMIG abbreviation can be expanded?

• changed

• Line 153: there are compounds in the Li2O-Al2O3 system between Al2O3 and LiAlO2, i.e. LiAl5O8 and LiAl11O17 - other "possible candidates".
• Info: LiAl5O8: 50 wt.% Al, LiAl11O17: 51.55 wt.% Al were omitted because of the substantial higher Al-content
• Changed: Therefore, corundum can be omitted. Other Li-aluminate phases like LiAl5O8 (50 wt.% Al), LiAl11O17 (51.55 wt.%) Al can therefore be omitted as well.
• Line 172: what means "coordination positions [4] and [8]"?
• Changed: In theory, Li+ can be present in 4 or 8 coordination, whereas the ionic radius is very similar to Mg (4‐coordination) or Na (8‐coordination) (e.g.,the ionic radii are published by Shannon [11])
• Line 174: rankinite is not a melilite endmember, because Ca is not listed on the second sublattice
• Info: A theory how rankinite can be treated as endmember for melilite-like alumosilicate solid solution is published in:
• Stracher, G.B. Crystallochemical Behavior of Slag Minerals and the Occurrence of Potentially New Mineral Species From Lapanouse-de-Sévérac, France. In Coal and Peat Fires: A Global Perspec-tive; Elsevier, 2019; pp. 243–300 ISBN 978-0-12-849885-9 à Table 13.2.22
• Changed: although not a endmember of the melilite solid solution
• Changed: Melilite to MCAS: Melilite-like alumosilicate
• Line 177: these endmembers may be not enough to define melilite, because none of them has Li on the second sublattice.
• Changed: Melilite to MCAS: Melilite-like alumosilicate
• Info: The theory of Li-incorporation into MCAS will be investigated in detail in the scope of a priority programme of the german research foundation (DFG). Most probably a refined model can then be presented
• Line 183: unclear what kind of modelling is mandatory, since the spinel can be expressed with three endmembers: MgAl2O4, LiAl5O8 and Al2O3 to a high accuracy.
• Info: The problem with the modeling is the behavior of spinel when rapidly cooled at high temperature without MgAl₂O₄ – Al₂O₃ exolution in presence of Li and LiAlO₂ as concurring phase.
• Changed: added: …in presence of LiAlO₂ as concurring phase…
• Fig.3-6 can be much improved if the phases are labelled. For example, the 8th free square can be used for a sketch of the figure with manually drawn lines and labelled phases.
• changed
• Line 251: if Mn in distributed to all phases, it should not be because of its high concentration - the ratios of concentrations are constant in a wide range according to Henry's law.
• Changed: Because of the presence of Mn
•  
• Probably the same for Na and K in line 317.
• Info: Not clear what to change
• Line 252-253: unclear sentence starting with "The ELAS(Mn)..."
• Changed: The ELAS(Mn) solid solution is different compared to the ELAS in the Mn-free material published by Schirmer et al. []
• Line 331: why "crystallization of spinel stopped in an earlier stage" - earlier than what?
• Changed …before the incorporation of the LiAl₅O₈ component into the spinel solid solution started…
•  

Grammar/terminology issues:

All changed

Line 30, 288: "pyrometallurgical" should not have a space

Line 148: phases

Line 153: minor component

Line 204: an alkali

Line 208: "monolithic" may be better to name "homogeneous"

Line 254: phase

Line 308: Whether

Line 323: a second

Line 326: solid (not capital)

Reviewer 4 Report

In this communication, the authors demonstrate the use of EnAM, EPMA and SIMS for the determination and analysis of Li in the slag produced from pyrometallurgical processing of lithium traction batteries. There are significant amounts of grammatical errors and improper expressions thorough out the manuscript that results in its very poor readability, which is unacceptable. Great effort should therefore be made to improve the English. The following lists some of the questions/concerns/comments.

 

1. Lines 31, Co, Ni and Cu are not noble elements. The description is wrong. These elements were originally in their oxide forms, which can be reduced by carbon at elevated temperatures to produce alloy. Li2O cannot be reduced by carbon. Therefore, it has nothing to do with nobility.
2. Line 96, “Li can be calculated using virtual compounds”. What does it mean? This is confusing.
3. Line 100, “Error! Reference source not found”
4. Line 254, “pahse”
5. Line 308, “Weather”
6. In the pyrometallurgical processing of the Li traction batteries, the material is essentially reduced by carbon generating molten alloy and slag. For those multi-valent elements (such as Mn), there is possible presence of Mn4+, Mn3+, and Mn2+ in the slag with great variation of stoichiometry. There could possibly be even glassy phase if the slag is cooled fast enough. How is this coped in the investigation?

Author Response

Dear Reviewer,

This letter contains the description of the requested revisions of our manuscript:

 Determination of the Li-distribution in synthetic recycling slag with SIMS

By Thomas Schirmer (corresponding author),  Michael Wahl, Wolfgang Bock and Michael Kopnarski.

First of all we would like to thank you for elaborately reviewing our paper.

This was very helpful and we learned a lot in terms to improve our future work. We hope the revision is according to your suggestions and our manuscript can be moved to the next processing step.

Thank you for your time and consideration.

Sincerely, Thomas Schirmer

The following text explanations how we responded to your comments on the revised version

Info: The authors apologize for the limited detailed argumentation. The article was ment to be a short communication to present first results of the Li-distribution in phases of pyrometallurgical slag. Detailed investigations will be carried out in the scope of a priority programme of the german research foundation (DFG)

1. Lines 31, Co, Ni and Cu are not noble elements. The description is wrong. These elements were originally in their oxide forms, which can be reduced by carbon at elevated temperatures to produce alloy. Li2O cannot be reduced by carbon. Therefore, it has nothing to do with nobility.
2. Changed: the valuable elements
3. Line 96, “Li can be calculated using virtual compounds”. What does it mean? This is confusing.
4. Changed:…like LiAlO₂  Mg_0.5AlO₂ and SiO2 in the case of a compound like Li_1-x(Al_1-xSi_x)O₂
5. Line 100, “Error! Reference source not found”
6. Info: This error was not recognized in the downloaded document but maybe due to field function of word. The functions are now removed
7. Line 254, “pahse”
8. Line 308, “Weather”
9. In the pyrometallurgical processing of the Li traction batteries, the material is essentially reduced by carbon generating molten alloy and slag. For those multi-valent elements (such as Mn), there is possible presence of Mn4+, Mn3+, and Mn2+ in the slag with great variation of stoichiometry. There could possibly be even glassy phase if the slag is cooled fast enough. How is this coped in the investigation?

Info: Using the virtual compounds LiMnO₂ , Mn_0.5AlO₂  (1/2 galaxite spinel), and Mn_0.5MnO₂  (1/2 hausmannite) includes Li and MnII/MnIII. Using a non-linear Generalized Reduced Gradient (GRG2) solving method a solution can be computed. The investigated material is a synthetic slag produced under controlled conditions to start an investigation of the phase formation especially of LiAlO₂. The real material coming from the process will definitely be more complex and will be assessed more intensely in the scope of a priority programme of the german research foundation (DFG).

Round 2

Reviewer 2 Report

The reviewer does not admit the methodological novelty of combining EPMA and SIMS as the authors claim in this paper, because it is generally known. However, the detailed study on the phase formation phenomena of the Li-bearing slag should be highly evaluated. The knowledge will be helpful to those who are considering the extraction of Li from Li-bearing slag.

The paper has been improved by this revision, but the typological errors should be revised before acceptance.

For example:
P.4, L. 183 "Li+" (superscript)
P. 6, L. 244 "maybe"
P. 10, L. 324 "of of"

Author Response

Dear Reviewer

This letter contains the description of the requested revisions (rev2) of our manuscript: 

Determination of the Li-distribution in synthetic recycling slag with SIMS

By

Thomas Schirmer (corresponding author),  Michael Wahl, Wolfgang Bock and Michael Kopnarski

First of all we would like to thank you for elaborately reviewing our paper for the second time.

Thank you for your time and consideration.

Sincerely, Thomas Schirmer

Enclosure:

The following text contains explanations how we responded to your comments on the revised version. 

Reviewer 2

the reviewer does not admit the methodological novelty of combining EPMA and SIMS as the authors claim in this paper, because it is generally known. However, the detailed study on the phase formation phenomena of the Li-bearing slag should be highly evaluated. The knowledge will be helpful to those who are considering the extraction of Li from Li-bearing slag.

The paper has been improved by this revision, but the typological errors should be revised before acceptance.

For example:
P.4, L. 183 "Li+" (superscript)
P. 6, L. 244 "maybe"
P. 10, L. 324 "of of"

Changed: All mentioned issues. Text was investigated to find remaining typographical errors

Reviewer 4 Report

The authors should further improve the English before publication. 

Author Response

Dear Reviewer

This letter contains the description of the requested revisions (rev2) of our manuscript: 

Determination of the Li-distribution in synthetic recycling slag with SIMS

By

Thomas Schirmer (corresponding author),  Michael Wahl, Wolfgang Bock and Michael Kopnarski

First of all we would like to thank you for elaborately reviewing our paper for the second time.

Thank you for your time and consideration.

Sincerely, Thomas Schirmer

Enclosure:

The following text contains explanations how we responded to your comments on the revised version.

Comments and Suggestions for Authors

The authors should further improve the English before publication. 

Changed: Text was thoroughly investigated to find remaining typographical errors and to improve the English. Unfortunately we found no native speaker to review the English in the tight timeframe of the mdpi review process. For the next article we will try to find a native speaker in an earlier stage of the article creation process (prior submission).