Influence of P and Ti on Phase Formation at Solidification of Synthetic Slag Containing Li, Zr, La, and Ta

Round 1

Reviewer 1 Report

Review report for ‘Influence of P and Ti on phase formation at solidification of synthetic slag containing Li, Zr, La and Ta’

Thank you for the interesting, although very long manuscript. Generally quite well written, although some parts were exhausting to read due to too much text. Below are detailed comments.

• You could add a citation to the following paper to the first part of the introduction, as it deals with the behavior of Li, La and Mn in pyrometallurgical copper smelting, with high-alumina slags: Dańczak A, Klemettinen L, Kurhila M, Taskinen P, Lindberg D, Jokilaakso A. Behavior of battery metals lithium, cobalt, manganese and lanthanum in black copper smelting. Batteries, 2020. Vol. 6. 16.
• Why did you choose a slag system without iron oxide(s)?
• Line 103: change “this” to “these”
• Line 143: what does “v” stand for in the Equation?
• Line 184: La₀₆₇TiO₃ is there a comma missing in 067?
• Line185: “an temperature conode” what does this mean?
• In my opinion, chapter 2 presents too many details which are unconnected to this work. The chapter (and subchapters within) can be significantly shortened.
• Line 278: is the word “ignoble” commonly used in this context? In my opinion, a better word could be found.
• Line 316: “wavelength dispersive or energy dispersive X-Ray fluorescence” please change the word “fluorescence” to “spectroscopy” to avoid confusion with the XRF method. Same applies to line 331.
• Lines 389-391: does this mean that you didn’t prepare the slags according to the modelled results in figure 1, but used some slags from another project? It is confusing.
• Lines 423-424: More of a general comment: even though your EPMA beam diameter is less than 1 µm, it does not mean that the analysis signal from the sample would come from such a small area. In reality, the signal comes from an area with a diameter of at least 5 µm, so this can be one reason for high Si concentration (if some signal comes from the surrounding phases due to small crystal size of the phase of interest).
• Lines 436 and 543: “ESMA” should probably be “EPMA”?
• Line 461: It would be better to use the same expression throughout the paper: mean atomic number vs mean ordinal number
• Titles of subchapters under chapter 4: use full names to make it easier to understand. SP = spinel etc.
• Line 572: revise
• Lines 573-575: Add some commas to make the sentence more understandable
• Line 605: Add a reference for the Newton Raphson method. Please also explain more how the phase composition percentages were calculated.
• Lines 811-812: How the cooling can be slower in this sample? You applied the same cooling rate to all samples, right?
• Chapter 5: it is very exhausting to read this chapter and form any clear image of what is happening. The chapter is far too long: try to make it shorter.
• Lines 847-857: combine these three paragraphs into one. No need to make several single sentence paragraphs like these.
• Conclusions and outlook: Add a notification that in the future, analysis methods capable of Li determination should be used to confirm your calculations. An example of such a method is LA-ICP-MS, if the grains are large enough (depending on the laser spot size used at least 50µm or preferentially larger)
• Author contributions: Use the format provided in the manuscript template: “Conceptualization, X.X. and Y.Y.; methodology, X.X.; software, X.X.; validation, X.X., Y.Y. and Z.Z.; formal analysis, X.X.; investigation, X.X.; resources, X.X.; data curation, X.X.; writing—original draft preparation, X.X.; writing—review and editing, X.X.; visualization, X.X.; supervision, X.X.; project administration, X.X.; funding acquisition, Y.Y. All authors have read and agreed to the published version of the manuscript”
• Revise the Conflicts of interest paragraph.
• Table 14: Explain why there are negative values, or remove the negative values from the table (replace with zero).

Author Response

Dear Reviewer,

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

 Influence of P and Ti on phase formation at solidification of synthetic slag containing Li, Zr, La and Ta

By

Thomas Schirmer (corresponding author) and Hao Qiu, Daniel Goldmann, Christin Stallmeister and Bernd Friedrich

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

Thank you for the interesting, although very long manuscript. Generally quite well written, although some parts were exhausting to read due to too much text. Below are detailed comments.

• You could add a citation to the following paper to the first part of the introduction, as it deals with the behavior of Li, La and Mn in pyrometallurgical copper smelting, with high-alumina slags: Dańczak A, Klemettinen L, Kurhila M, Taskinen P, Lindberg D, Jokilaakso A. Behavior of battery metals lithium, cobalt, manganese and lanthanum in black copper smelting. Batteries, 2020. Vol. 6. 16.
• Changed: Ref. included – Reference list updated: all reference numbers starting from 3 are now +1 until 18 (was 17)
•  
• Why did you choose a slag system without iron oxide(s)?
• Answer: The selection of the elements is based upon the referenced slag-forming oxides depicted in table 1
• Line 103: change “this” to “these”
• Changed: (was at line 106)
• Line 143: what does “v” stand for in the Equation?
• Changed: v stands for vacation. Now in brackets (“vacant position”)
• Line 184: La₀₆₇TiO₃ is there a comma missing in 067?
• Yes: Changed (found several places)
• Line185: “an temperature conode” what does this mean?

Changed: Conode is the term used to describe lines connecting state points in phase diagrams of thermodynamic systems, which are based on phase boundary lines ...: rewritten as “conode (boundary line)”

• In my opinion, chapter 2 presents too many details which are unconnected to this work. The chapter (and subchapters within) can be significantly shortened.

Changed: unrelevant information (z.B. Info about Mg containing compounds are removed). Reference list updated: all reference numbers from 26 on are now -3.

• Line 278: is the word “ignoble” commonly used in this context? In my opinion, a better word could be found.

Changed: removed, replaced by “the”

• Line 316: “wavelength dispersive or energy dispersive X-Ray fluorescence” please change the word “fluorescence” to “spectroscopy” to avoid confusion with the XRF method. Same applies to line 331.

Changed

• Lines 389-391: does this mean that you didn’t prepare the slags according to the modelled results in figure 1, but used some slags from another project? It is confusing.

Changed: Three interesting SyS were available from the set of samples out of the campaign produced via the approach described in chapter 4.1

• Lines 423-424: More of a general comment: even though your EPMA beam diameter is less than 1 µm, it does not mean that the analysis signal from the sample would come from such a small area. In reality, the signal comes from an area with a diameter of at least 5 µm, so this can be one reason for high Si concentration (if some signal comes from the surrounding phases due to small crystal size of the phase of interest).

Answer: The excitation bulb is actually much larger due to the higher analysis volume of characteristic X-Rays. However, the silicon contents are also measurable in large grains of LiAlO₂ (e.g. Figure 2, ledges with more than 10µm diameter and several 100 µm length).

• Lines 436 and 543: “ESMA” should probably be “EPMA”?

Changed: This was the german term: change to EPMA

• Line 461: It would be better to use the same expression throughout the paper: mean atomic number vs mean ordinal number

Changed: mean atomic number used throughout the whole text

• Titles of subchapters under chapter 4: use full names to make it easier to understand. SP = spinel etc.

Changed: Full names no displayed with abbreviation in brackets

• Line 572: revise

Changed: wrong text deleted

• Lines 573-575: Add some commas to make the sentence more understandable

Changed: two commas added

• Line 605: Add a reference for the Newton Raphson method. Please also explain more how the phase composition percentages were calculated.

Changed: More explanation with a reference to the used program (Excel) added. The algorithm seems to be very similar to the Newton Raphson method, but finally I was not able to find the algorithms actually build into Excel. So I removed the reference to the Newton Raphson method and put in a reference to Excel. There it is described how to use this functions but unfortunately the algorithms are not mentioned.

• Lines 811-812: How the cooling can be slower in this sample? You applied the same cooling rate to all samples, right?

Changed: This is correct (after asking the experimenters) – I changed the interpretation with the suggestion that the crystallization temperature of the phases depends on the chemistry.

• Chapter 5: it is very exhausting to read this chapter and form any clear image of what is happening. The chapter is far too long: try to make it shorter.

Changed: Shortened an rearanged

• Lines 847-857: combine these three paragraphs into one. No need to make several single sentence paragraphs like these.

Changed

• Conclusions and outlook: Add a notification that in the future, analysis methods capable of Li determination should be used to confirm your calculations. An example of such a method is LA-ICP-MS, if the grains are large enough (depending on the laser spot size used at least 50µm or preferentially larger)

Changed: sentence included

• Author contributions: Use the format provided in the manuscript template: “Conceptualization, X.X. and Y.Y.; methodology, X.X.; software, X.X.; validation, X.X., Y.Y. and Z.Z.; formal analysis, X.X.; investigation, X.X.; resources, X.X.; data curation, X.X.; writing—original draft preparation, X.X.; writing—review and editing, X.X.; visualization, X.X.; supervision, X.X.; project administration, X.X.; funding acquisition, Y.Y. All authors have read and agreed to the published version of the manuscript”

Changed: Adapted

• Revise the Conflicts of interest paragraph.

Changed: Revised

• Table 14: Explain why there are negative values, or remove the negative values from the table (replace with zero).

Changed: I found negative values in table 14 (Appendix) and replaced them with zero

Reviewer 2 Report

Dear authors,

In your manuscript, you have correctly presented the obtained results of the selected composition of synthetic slag. Also, you logically discuss the influence of selected elements La, Ta, Zr and Li on the process of formation of mineral phases.

I think the following should be done:

1. You describe: The pressure is set to one atm and equilibrium is calculated. Due to the limited data for the contained REE La and Ta, they cannot be taken into account in the model. Additional Al₂O₃ as well as SiO₂, CaO and P₂O₅ were considered common fluctuating components. Their influence on the liquid slag temperature for different amounts of these oxide additives was studied. Discuss what happens if some or all of these oxides are not contained in the slag.

2. In the Abstract, change the following:

In this manuscript, methods for determining .......... were developed, presented or optimized, and the obtained results were discussed, either: a tested model of the application of phosphorus and titanium additives on the behavior of synthetic slag. For this purpose, oxide slags were synthesized with Al, Si, Ca and additives P and Ti and done ....................... Based on the obtained results, it can be to conclude

3. State in the text of your manuscript:

 In the samples with Ti and P (ASSB-1) and without both (ASSB-10) most of the bulk Li is distributed over LiAl and Ec. ASSB-10 tends to have a higher amount of Matrix at the expense of eucryptite. You also state that Li has a clear affinity for P to form LiP based on the general formula X₃YO₄ (X: Li; Y: P (Si).) resp.).

What do you think? Whether the resulting residual phosphorus-rich melt leads to the crystallization of LiP, or whether aluminum and silicon have already been removed with lithium in the initial phase of crystallization. Discuss this based on the results obtained. What is the influence of the shape and size of the grain in the cooling phase, ie the cooling curve.

With respect   

Author Response

Dear Reviewer,

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

 Influence of P and Ti on phase formation at solidification of synthetic slag containing Li, Zr, La and Ta

By

Thomas Schirmer (corresponding author) and Hao Qiu, Daniel Goldmann, Christin Stallmeister and Bernd Friedrich

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

I think the following should be done:

1. You describe: The pressure is set to one atm and equilibrium is calculated. Due to the limited data for the contained REE La and Ta, they cannot be taken into account in the model. Additional Al₂O₃ as well as SiO₂, CaO and P₂O₅ were considered common fluctuating components. Their influence on the liquid slag temperature for different amounts of these oxide additives was studied. Discuss what happens if some or all of these oxides are not contained in the slag.

 Changed: new text before Table 1: The process temperature of the melting tests is 1500 °C. Accordingly, the liquidus temperature of the material mixture must be lower. Without the addition of the fluxing components to the mixture of the slag-forming oxides from possible battery compositions, the slag would be too high-melting (see section 4.1, figure 1).

1. In the Abstract, change the following:

In this manuscript, methods for determining .......... were developed, presented or optimized, and the obtained results were discussed, either: a tested model of the application of phosphorus and titanium additives on the behavior of synthetic slag. For this purpose, oxide slags were synthesized with Al, Si, Ca and additives P and Ti and done ....................... Based on the obtained results, it can be to conclude

Changed: The text blocks were adapted and placed into the appropriate positions in the abstract

1. State in the text of your manuscript:

 In the samples with Ti and P (ASSB-1) and without both (ASSB-10) most of the bulk Li is distributed over LiAl and Ec. ASSB-10 tends to have a higher amount of Matrix at the expense of eucryptite. You also state that Li has a clear affinity for P to form LiP based on the general formula X₃YO₄ (X: Li; Y: P (Si).) resp.).

What do you think? Whether the resulting residual phosphorus-rich melt leads to the crystallization of LiP, or whether aluminum and silicon have already been removed with lithium in the initial phase of crystallization. Discuss this based on the results obtained. What is the influence of the shape and size of the grain in the cooling phase, ie the cooling curve.

Changed: Tried to clarify the observation that a P-rich residual melt forms and separates from a more silicious melt with higher concentration of Si,Al and Ca and that if this were true the solubility of Si and especially Al and Ca in this P-rich melt is very low (chapter from line 707 – 719).

Added to the text: If large crystals form from a few nuclei at an early stage of solidification, this could be (thermodynamically) advantageous for the further growth of crystal blocks or structures onto the comparably large surfaces of these large crystals.

Round 2

Reviewer 1 Report

I am satisfied with the changes made, and from my side you can proceed with the manuscript.
So, my recommendation is "accept in present form".