Magnesium Oxide Production by Plasma Chemical Conversion from Fluorine-Containing Industrial Waste
Round 1
Reviewer 1 Report
1. The review of previous studies is not adequate there is need to enhance the literature review section
2. In the last paragraph of the objectives, there is need to clearly explain the research problem, research gap, and research objectives.
3. In the materials section please add a Table for the properties of all the materials used Include some Figs of the materials and experimental methods
4. The results findings need to be compared with previous studies
5. The results sections need to be broken into sub sections for ease of reading and understanding
6. The conclusions need to be rewritten, please carefully study the objectives and findings and then draw conclusions from them
7. Avoid use the words “we”, “our” Please report your findings in passive form
8. Proofread the manuscript throughout to correct all grammatical errors
Author Response
Q.1: The review of previous studies is not adequate there is need to enhance the literature review section
Answer: The literature review section (introduction) has been corrected.
Q.2: In the last paragraph of the objectives, there is need to clearly explain the research problem, research gap, and research objectives.
Answer: The Introduction section has been edited accordingly.
Q.3: In the materials section please add a Table for the properties of all the materials used Include some Figs of the materials and experimental methods
Answer: In the materials section, the characteristics of the initial powder, magnesium fluoride, have been added.
Figures and results of thermogravimetric analysis have been added.
Q.4: The results findings need to be compared with previous studies
Answer: Magnesium fluoride recycling (industrial beryllium production waste) by plasma chemical treatment has no analogues. Magnesium fluoride is a unique industrial waste in that it is formed as a result of magnesothermal reduction of beryllium fluoride. Only Kazakhstan and the USA use this technology to produce beryllium in the world.
The authors have previously carried out works on the steam plasma treatment of CaF2, which is a part of beryllium concentrate. However, negative results were obtained.
Based on this, there is no publication of previous studies.
Q.5: The results sections need to be broken into sub sections for ease of reading and understanding
Answer: The article considers the results of works on determination of optimal granulometric composition for completeness of conversion process of magnesium fluoride to magnesium oxide. From the results of plasma-chemical treatment of powder magnesium fluoride with different fractions follows the conclusion about the efficiency of plasma-chemical treatment of magnesium fluoride in the form of briquettes (not as a powder).
On this basis, the authors think that dividing the results into subsections is not effective for describing the overall picture of the work.
Q.6: The conclusions need to be rewritten, please carefully study the objectives and findings and then draw conclusions from them
Answer: According to the reviewer's comment, the conclusions are rewritten.
Q.7: Avoid use the words “we”, “our” Please report your findings in passive form
Answer: According to the Reviewer's comment, the words "we" and "our" are reformulated.
Q.8: Proofread the manuscript throughout to correct all grammatical errors
Answer: According to the reviewer's comments, the section "Introduction" was revised and edited.
References [5,6] were changed to the appropriate references according to the subject of this paper.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Referee report on “Magnesium oxide production by plasma chemical conversion from fluorine-containing industrial waste” by Zhuldyz Sagdoldina et al
This is a quite interesting article that can be recommended for publication, but after clarifying and detailing some parts of the text.
1. Although the introduction is written in detail, nevertheless there are several shortcomings. a) the second paragraph contains no supported references at all; b) lines 59. References [5,6] These references do not refer to oxides, so this proposal needs to be modified. As for oxides and halides, see, very recent paper :
Lisitsyna, L.A., et al. Luminescence of MgF2-WO3 ceramics synthesized in the flux of 1.5 MeV electron beam. Optical Materials, 2022, 133, 112999 https://doi.org/10.1016/j.optmat.2022.112999
2. The motivation for the study is not fully disclosed. Looking at Figure 8, where MgF2 and MgO briquettes are shown as the final product, it is clear that these materials are not suitable for optical applications. However, such briquettes may be of great interest for nuclear and fusion applications where these materials are still on the priority list.
Popov, A. I. et al. Thermal annealing of radiation defects in MgF2 single crystals induced by neutrons at low temperatures. Nucl. Instrum. Methods B 480, 16–21 (2020).
Monge, M.A.; et al. Photoconversion of F+ centers in neutron-irradiated MgO. Nucl. Instrum. Methods Phys. Res. Sect. B 166, 220–224 (2000).
3. Despite the successful synthesis, it is necessary, at least briefly, to explain why these materials are better than real commercial ones? Even short analysis of other new methods published recently would also be useful, especially to attract a wider readership.
4. The quality of the following drawings is clearly insufficient, because small details are indistinguishable: 4 (a,c), 5 (a, c) and 6 (a, c).
5. What is the porosity of the synthesized samples and how does this affect their physical and technical properties?
6. In the conclusions, it is necessary to clearly formulate what new data about the studied materials were obtained in this work?
In general, the manuscript is interesting and can be recommended for publication after constructive reflection on the above comments.
Author Response
Answer 1: According to the reviewer's comments, the section "Introduction" was revised and edited.
References [5,6] were changed to the appropriate references according to the subject of this paper.
Answer 2: This article does not consider the optical applications of MgF2 and MgO. Briquetting MgF2 was used to increase the homogeneity of the chemical process in the plasma. And magnesium oxide is planned to be used as a material for high-temperature applications such as refractory protection. In order not to mislead readers, we made adjustments to Figure 8.
We agree with the reviewer, magnesium fluoride is of great interest for nuclear and thermonuclear applications. In the "Introduction" section, information on magnesium fluoride applications has been added and relevant references to the literature have been taken into consideration.
Answer 3: The aim of this work is to recycle industrial waste by plasma chemical treatment. From industrial waste magnesium fluoride, which is a waste from beryllium production, we get magnesium oxide using steam plasma in the reaction MgF2 + H2O→MgO + 2HF.
The plasma-chemical method of processing industrial wastes can be applied instead of the existing method of magnesium fluoride processing by hydrometallurgical method, which is dissolved in acids and alkalis with subsequent precipitation of magnesium oxide and withdrawal of fluoride-containing products by concentrating or evaporation of solutions.
Application of plasma chemical treatment for magnesium fluoride has no analogue, as it is a unique industrial waste, which is formed as a result of magnesothermal reduction of beryllium fluoride. There are so many 4 countries in the world engaged in beryllium production (Kazakhstan, USA, China, Russia). Kazakhstan and USA get beryllium according to the technological scheme, reducing beryllium fluoride by magnesium according to the chemical reaction: BeF2+Mg→MgF2+Be.
Therefore, there are very few publications on the subject of this article to analyze the methods of recycling industrial waste.
Answer 4: Figures 4, 5, 6 have been changed.
Answer 5: In the framework we considered the composition of the initial powders for briquetting, the smaller the powder fraction, the greater the density of briquettes, on this basis, this work does not set the task of determining the porosity of briquettes
Answer 6: According to the reviewer's comment, the conclusions are changed.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Authors have addressed all my comments
Reviewer 2 Report
The authors have significantly improved their original manuscript, which now can be recommended
For publication.
