Phase Transitions in the α–γ–β Spodumene Thermodynamic System and Impact of γ-Spodumene on the Efficiency of Lithium Extraction by Acid Leaching

Round 1

Reviewer 1 Report

Authors have studied the impact of phase transitions in spodumene allotropes with respect to lithium extraction efficiency. This manuscript may be accepted after minor revision.

Abstract section: line11: please charge "during" to "for"

Abstract section: line 12: please delete "up to"

Abstract section: line 14: please change "grinded" to "ground". Similar mistakes on page 7: line 261; on page 8: line286.

On page 6; line 222: please change "chloric acid" to "hydrochloric acid"

On page 6: line 222: please change "fluoric acid" to "hydrofluoric acid"; similartly on line 227

Any thermodyamic properties of gamma-spodumene similar alpha-spodumene and beta-spodumene in Table 1 and 2?

Additional experiments such as FTIR spectra on all three forms of spodumenes could provide further insight into structures.

On page 21; line 662: strange sentence: sugestions: and the mechanism should be studied in the future.

Author Response

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Reviewer 2 Report

The manuscript assumes the research about impact of structure of spodumene on the efficiency of lithium extraction by acid leaching. The extraction lithium from ores (specially sposumene) is well known method and extensively study in last years. The paper exhibit a lot of data and analysis however below authors can find a critical comments:

1. Scale at Figures 1 and 2 should be more visible and provide for each of images
2. The all of figures should have the frame around graphs (like at Figure 8)
3. The manuscript will have more scientific impact if your present the different ratio of extraction of lithium from different phases of spodumene at one graph and compare it. It could be worth to show the extration ratio for these three phases. 
4. Next, it could be also good that the authors can present the elementary analysis (percentage of each element at sample) before and after acid leaching to present differences of extraction depends on spodumene phases

After finalizing above recommendations, presented manuscript could be considered for publication in Minerals MDPI Journal.

Author Response

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Reviewer 3 Report

Ref No: minerals-768498

Title:  Impact of phase transitions in the α-γ-β spodumene 2 thermodynamic system on the efficiency of lithium extraction by acid leaching

 

General Comment:

  The motivation and interest of the investigation has enough novelty and specific to the interest of a defined problem. The paper lacks a well-organized presentation and presented extensively instead of precisely. Title and subject matter not reflecting proportionately, making hard to keep focused to read the manuscript. I have observed haphazardness in the manuscript makes the reader jump back and forth in the manuscript to make a sense of motivation and interest. Hence, my recommendation would be rewriting the manuscript, make it precise, organized, lucid to read, and focused for understanding. Like: divide the results and discussion into 3 parts, i.e. (i) Section I: heat treatment, phase transition because of heat treatment like α-γ-β spodumene, section II: Phase transition and its effect on lithium leaching/extraction do not yield, section, III: thermodynamically significance. I would rather recommend a more extensive investigation on leaching efficiency on γ spodumene on β spodumene.

 

 

Specific Comments: I have observed lots of jargon and wordy presentations all over the manuscript which need proficient attention.  I have listed some below.

• The title is not reflecting the interest of the paper completely, hence, the title should be modified. Like the impact of γ spodumene on lithium extraction efficiency and thermodynamics or like that.
• The introduction should mention the investigation, motivation, and novelty/significance of the research.
• Line 163, what is liquid lithium bisulfate: It should be aqueous lithium bisulfate?
• Section 2.5 introduced the facts age investigation.
• Combine Tables 1 and 2, make it 1, and precisely explain Gibb's evaluation and relationship with the title of studies, like leaching efficiency and phase transition study.
• There is no explanation about Figure 3a, only explanation about 3b there.
• Line 341 Figure 1 is an error it should be Figure 5.
• Combine sections 3.2 and 3.4 through reorganization.
• Line 286, and 375: lithium yield: Do you mean lithium extraction efficiency. I think lithium extraction efficiency would be more appropriate terminology for metallurgist, hence, its use recommended all over the manuscript.
• Table 5 and Figure 6 double presentation of the same data fundamentally not accepted way of presentation.
• Line 438: Subsequent solvent extraction? subsequent leaching and solvent extraction.
• When using irreversible better use β -γ- α spodumene sequence, which is meaning full otherwise expression is invalidated. Example: Line 444. 462-463
• Line 459: new XRD pattern: better coin right and appropriate terminology.
• I would bring figure 8 values to Table 6 and make a precise presentation.
• The chemical expression below line 498, 509, 526.547,581 no equation number, hence, formal presentation recommended. Better use one equation and refer it. I would combine the 9-13 figure into 1 Figure and describe it.
• Rewrite conclusion, no need to tell the whole story in conclusion, just tell us what the take-home from the manuscript is.

 

Remark: Take home from reading the whole manuscript is not straightforward, one must dig it. Make is straightforward what is take home for the reader from the paper.  

 

Recommendation: extensive and major revision recommended.

Author Response

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Reviewer 4 Report

The paper is very interesting with many experimental and analytical results. The authors accurately presented the results of their research. The manuscript has been carefully prepared and the topic was a good fit to this journal. I suggest to accept the paper.

Minor editorial shortcomings:

• Line 118, would be indicated in section 2.1. provide designation of test samples,
• Line 341, is: Figure 1 – should be: Figure 5,
• In References, e.g. Line 703, is: N. P. Kotsupalo, L. T. Menzheres,….- should be: Kotsupalo, N. P., Menzheres L. T.,….

Author Response

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Round 2

Reviewer 3 Report

Though the manuscript has been improved, the author has not considered all the suggestions. I would suggest if the author would relook into my recommendation. Some figure and section should combine as I suggested.

 

 

Author Response

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