Purification of Organosilicon Waste Silicon Powder with Hydrometallurgy

Round 1

Reviewer 1 Report

Please, read carefully comments in the attached file. There is a lot of work needed before this manuscript could be published in Metals.

Comments for author File: Comments.pdf

The manuscript is well written, however there are too many generalizations which may make it difficult for some readers to understand the text.

Author Response

Dear Editor,

Thank you for your effort in evaluating our manuscript and the reviewers’ comments on our paper entitled “Purification of Organosilicon Waste Silicon Powder with Hydrometallurgy”. According to the kind comments, we have revised the manuscript carefully. The revised contents were highlighted by red text in the revised manuscript (marked version).

Our point-by-point responses to the constructive comments are listed below:

1. Dot should be placed after the bracket.

R: Thanks for the kind reminding, the wrong formats of all references were corrected in the revised manuscript.

2. The title of the paper relates to waste silicon powder. Is it the same phase as organosilicon slag? Maybe, it would be better to modify the title of the work?

R: Thanks for the kind reminding. Waste silicon powder is the same phase as organosilicon slag. We have revised the title of the work in the revised manuscript.

3. Please, state the goal of this work. Refer to the title of your work. What has been done so far? Cite other authors works dealing with hydrometallurgical processing of silicon wastes. It seems that the introduction part is incomplete. Point the knowledge gap, show what you want to study.

R: The goal of this work is to recover and utilize waste silicon powder produced in the organosilicon materials production. During the past few years, some well-known acid leaching processes have been used in industry, including HNO₃ or HCl acid washing, HCl leaching, H₂SO₄ leaching, HCl + HF leaching, multivariate acids system leaching, and microwave mixed acid leaching. However, there are few researches on acid leaching treatment of waste silicon powder produced in the production process of organosilicon materials. Therefore, the purification of silicone waste slag with hydrometallurgy is very significant, which can improve the recycling rate of silicon powder and realize continuous scale production.

Thanks for the constructive comment, we have carefully checked the introduction parts and they were rewritten and re-organized in the revised manuscript.

4.The simple production scheme showing the waste silicon powder origin should be inserted.

R: The waste silicon powder was obtained from the production of organosilicon materials. The direct method is a crucial step in the production of organosilicon, where a fluidized bed is typically used as the reaction site for the raw materials. However, due to the structure of the fluidized bed equipment itself, the reaction does not proceed ideally, resulting in residues of unreacted raw materials, including silicon powder and Cu catalyst. Although these residues did not undergo a chemical reaction, they remain in the fluidized bed for a long time, leading to the accumulation of other materials, such as organic matter generated by the reaction, which results in a complex composition. These wastes are discharged with the reaction system, forming waste silicon powder.

Thanks for the kind reminding, the production scheme of the waste silicon powder was inserted in the revised manuscript.

5. The composition of impurities was measured with SEM? what is the accuracy of the method?

R: Thanks for the kind comment. The concentrations of impurities in waste silicon powder were tested by ICP firstly. Then SEM equipped with EDS was used to further analyze existing forms, and microscopic morphology of the impurities in the waste silicon powders. Therefore, the accuracy of the methods which combine ICP, SEM and EDS to study the composition, existing forms, and microscopic morphology of the impurities is reliable.

6. Does it mean that solid waste silicon samples were digested before and after leaching?

How? Please, give the procedure. How the content of impurities was calculated?

R: Sorry for the vague description in the manuscript. It doesn’t mean that solid waste silicon samples were digested before and after leaching. We examined the change of impurity content in waste silicon powder before and after leaching by ICP. The content of impurities is tested according to the national standard for testing silicon.

Thanks for the kind comment, the detailed description of impurities test methods in silicon were provided in the Experimental part.

7. Please, state the leaching procedures for the listed experiments.

R: Firstly, concentration condition experiments were carried out for hydrochloric acid and hydrofluoric acid leaching separately to determine the optimal concentration for each single acid system, which would serve as the basis for subsequent studies on mixed acid leaching. Secondly, based on the optimal concentration of single acid system leaching, a mixed acid solution of 1 M HCl + 4 M HF was prepared for the leaching experiments. Additionally, a 0.5 M H₂O₂+ 4 M HF mixed acid solution was also used for the mixed acid system leaching experiments. At last, metal-assisted chemical etching was employed, which creates porous structures on the surface of the waste silicon powder, exposing the impurities encapsulated inside the residue. The samples were dipped into the Cu(NO₃)₂/HF mixture [Cu(NO₃)₂ = 4 mM, HF = 4 M] solution for deposition of Cu nanoparticles (CuNPs) for 60 s, and then 0.5 M H₂O₂ was added to the Cu(NO₃)₂/HF solution, with a leaching time of 2 h.

Thanks for the kind comment, the leaching procedures for the listed experiments were provided in the Experimental part.

8. There is lack of Fe map. Why?

R: Actually, due to impurity Fe main from raw material industrial silicon, and the distribution of Fe is not concentrated but is distributed scattered as an alloy state in the industrial silicon[31, 32]. Therefore, the presence of Fe was not detected in the waste silicon powders by scanning electron microscopy..

Thanks for the kind reminding, the reason for lacking Fe map was further added in the revised manuscript.

[31] Lei, Y., Ma, W., Lv, G., Wei, K., Li, S., & Morita, K. (2017). Purification of metallurgical-grade silicon using zirconium as an impurity getter. Separation and Purification Technology, 173, 364-371.

[32] Xi, F., Li, S., Ma, W., Ding, Z., Lei, Y., Chen, Z., ... & Wu, J. (2018). Removal of impurities from metallurgical grade silicon with metal assisted chemical leaching. Hydrometallurgy, 178, 250-255.

9. SEM analysis showed that organosilicon is a tiny part of waste silicon powder, which is the main phase. So, the phrase 'organosilicon waste silicon powders' should be shorten to 'waste silicon powders' throughout the text.

R: Thanks for the kind suggestion, we have replaced organosilicon waste silicon powders with waste silicon powders in the revised manuscript.

10. It is not included in this version. please, add all the supplementary materials after main text. you can separate them after the article is accepted.

R: Thanks for the kind reminding, we have added the Supporting Information in the revision.

11. It seems that impurities are part of the main silicon powder phase. Not the organosilicon needles. Thus, the title is not correct.

R: Thanks for the kind reminding, we have revised the title in the revised manuscript.

12. The title should be shorten to: Main impurities content after HCl leaching. However, it is not clear to what phase the content relates to.Also, rename first column to"HCl conc., M". Please, see comment at Table 2

R: Thanks for the kind reminding, we have revised the title and the first column name of Table1 and Table 2 in the revision.

13. What insoluble in HCl salts of Cu, Al or Fe can be part of the silicon waste? Please, give some example.

Actually, the chlorides of Cu, Al or Fe all are soluble, therefore the explanation for low removal efficiency of Al with HCl was incorrect in the original manuscript. According to the constructive comments, we have searched a large amount of literatures, which found that the temperature have an important effect on Al removal from Silicon with HCl. Our experiments were carried on the room temperature, resulting in the low removal efficiency of Al.

Thanks for the kind comment, the description of low removal efficiency of Al were revised in the revision.

14. What other leaching parameters could be changed to improve leaching efficiency?

R: Thanks for the kind reminding. Acid concentration, leaching time and leaching temperature could be changed to improve leaching efficiency.

15. Is it practical to increase HF concentration? Are there any other factors leading to more effective impurities removal?

R: Thanks for the kind reminding. Previously, other conditions including acid concentration, leaching time and leaching temperature and so on have studied. It was found that the concentration had the greatest influence and the best removal effect. Therefore, the experiment only exhibited the effect of HF concentration on impurity removal.

16. It is clear from the fig. 4. there is no point to repeat the same statements.

R: Thanks for the kind reminding, we have revised the statements in the revision.

17. Explain what is the reasoning for using this additional system.

R: Thanks for the kind reminding. A 0.5M H₂O₂+4M HF mixed acid solution was used for the leaching experiments. In the hydrofluoric acid leaching experiments, the best results were achieved with 4.0 M HF leaching, and choosing 0.5M H₂O₂ mainly based on our previous research work ^{[33, 34].}

[33] Xi F, Li S, Ma W, et al. Simple and high-effective purification of metallurgical-grade silicon through Cu-catalyzed chemical leaching[J]. Jom, 2018, 70: 2041-2047.

[34] Xi, F., Cui, H., Li, Y., Ding, Z., Li, S., Ma, W., ... & Wu, J. (2019). Novel enhancing impurities purification from silicon powder through metal-catalyzed chemical corrosion. Powder technology, 352, 53-61.

18. Have you used ICP-OES to earlier experiments? Or you are comparing the results from SEM to results from ICP-OES? Please, explain this.

R: The impurities content in silicon of all experiments were tested by ICP. As shown in Figure 2, the SEM results are highly consistent with the main impurities which detected by ICP.

Thanks for the kind reminding, the corresponding descriptions were added in the revised experimental steps

19. Where the content was determined? in solid or liquid phase?

R: Sorry for the vague description in the manuscript. The content was determined in solid phase. According to the kind comments, the corresponding descriptions were added in the revised experimental steps

20. This part is rather a list of observations repeated from previous sections. How these results can be usefull for other researchers or industry? What method would you propose eventually for silicon purification?

R: Thanks for the kind comment. The study provided a simple and feasible method for efficient recycling of organosilicon waste residue, which may solve the long-standing problem in organosilicon enterprises. We proposed Cu-assisted chemical etching to purify waste silicon powder. The method has the obvious effect of removing impurities It is worth noting that CuACE treatment has a remarkable ability to remove more than 95% of Fe through hydrometallurgy.

21. These are empty phrases: 'the best',' the second' and 'relatively poor' means nothing to the readers. Please, support your conclusions with specific values.

R: Thanks for the kind suggestion, the empty phrases were revised, and replaced with specific values in the revised manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper tackles and important problem - recycling silicon powder. After identification of the main metal impurities different hydrometallurgy systems have been studied for their ability to remove the impurities. Copper-assisted chemical etching is proposed as the most effective method for removing impurities from the studied waste material (organosilicon waste silicon powder). The probable mechanism is proposed schematically with the aim to explain the effect of the copper-assisted chemical etching.

Generally well organized paper with logically presented results. The CuACE system and the samples preparation for the ICP analysis have to be described at least with 1-2 sentences.

Proposals for some small corrections and some comments are in the attached file with the aim to facilitate authors. Interest to the readers is ticked as ''average'' mainly because of the relatively narrow scientific community working in the studies area. 

Comments for author File: Comments.pdf

Minor editing of English language

Author Response

Dear Editor,

Thank you for your effort in evaluating our manuscript and the reviewers’ comments on our paper entitled “Purification of Organosilicon Waste Silicon Powder with Hydrometallurgy”. According to the kind comments, we have revised the manuscript carefully. The revised contents were highlighted by red text in the revised manuscript (marked version).

Our point-by-point responses to the constructive comments are listed below:

1. After samples digestion with? Please specify how exactly the concentration of impurities was determined.

R: In this paper, the concentration of impurities before and after acid leaching were determined dried and digested using inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and the test method was followed with Chinese testing standards of GB/T 14849.4-2014. Sorry for the vague description in the manuscript, the detailed description of impurities test methods in silicon were provided in the Experimental part.

2. Figure 1 and Figure 6: Silicon, not silicone.

R: Thanks for the kind reminding, we have revised the mistakes in the Figure 1 and Figure 6.

3. Unclear, please revise.

R: Thanks for the kind reminding, we have revised the unclear expressions in the revision.

4. What is on the first figure-Fe?

R: Actually, due to impurity Fe main from raw material industrial silicon, and the distribution of Fe is not concentrated but is distributed scattered as an alloy state in the industrial silicon[31, 32]. Therefore, the presence of Fe was not detected in the waste silicon powders by scanning electron microscopy..

Thanks for the kind reminding, the reason for lacking Fe map was further added in the revised manuscript.

[31] Lei, Y., Ma, W., Lv, G., Wei, K., Li, S., & Morita, K. (2017). Purification of metallurgical-grade silicon using zirconium as an impurity getter. Separation and Purification Technology, 173, 364-371.

[32] Xi, F., Li, S., Ma, W., Ding, Z., Lei, Y., Chen, Z., ... & Wu, J. (2018). Removal of impurities from metallurgical grade silicon with metal assisted chemical leaching. Hydrometallurgy, 178, 250-255.

5. Which insoluble salts? The context implied salts of Al, but AlCl₃ is water soluble. Please clarify.

R: Thanks for the kind reminding, the chloride of Al is soluble, therefore the explanation for low removal efficiency of Al with HCl was incorrect in the original manuscript. According to the constructive comments, we have searched a large amount of literatures, which found that the temperature have an important effect on Al removal from Silicon with HCl. Our experiments were carried on the room temperature, resulting in the low removal efficiency of Al.

Thanks for the kind comment, the description of low removal efficiency of Al were revised in the revision.

6. How the formation of AIF3 causes the removal rate decrease? It is water soluble.

R: Thanks for the kind reminding. Actually, AlF₃ is water soluble.However, the insoluble salts of Al₂(SiF₆)₃ will generated from impurity Al with high concentration HF acid, and the results are also consistent with experimental phenomena from other reachers [34, 35].

Sorry for the vague description in the manuscript, the detailed description of fluoride of Al₂(SiF₆)₃ were provided in the Experimental part.

[34]      Xi, F., Cui, H., Li, Y., Ding, Z., Li, S., Ma, W., ... & Wu, J. (2019). Novel enhancing impurities purification from silicon powder through metal-catalyzed chemical corrosion. Powder technology, 352, 53-61.

[35]      Lai, H., Huang, L., Gan, C., Xing, P., Li, J., & Luo, X. (2016). Enhanced acid leaching of metallurgical grade silicon in hydrofluoric acid containing hydrogen peroxide as oxidizing agent. Hydrometallurgy, 164, 103-110.

7. Some information about the etching solution is needed.

R: The etching solutions in Cu-assisted chemical etching leaching include 4 mM Cu(NO₃)_2, 4 M HF and 0.5 M H₂O₂. The samples were dipped into the Cu(NO₃)₂/HF mixture [Cu(NO₃)₂ = 4 mM, HF = 4 M] solution for deposition of Cu nanoparticles (CuNPs) for 60 s, and then 0.5 M H₂O₂ was added to the Cu(NO₃)₂/HF solution, with a leaching time of 2 h.

Thanks for the kind suggestion, the detailed description of etching solutions were provided in the Experimental part.

8. Do you have in mind cu ions ? If yes , specify please.

R: The etching process starts with the nucleation of Cu²⁺ into Cu nanoparticles, which are deposited on the surface of the organosilicon waste silicon powder. This leads to the formation of a primary cell between the Cu nanoparticles and the silicon substrate, with the Cu nanoparticles acting as the cathode and the silicon substrate as the anode. In the presence of Cu nanoparticles, H₂O₂ in the etching solution creates holes (h+) in the valence band of silicon, catalyzed by the Cu nanoparticles. This results in the oxidation of the silicon in contact with the bottom of the Cu nanoparticles, and the electrons produced by the silicon oxidation further promote the reduction of oxide species. This electrochemical reaction occurs spontaneously on the surface of the silicon. The redox reaction above leads to continuous oxidation of the silicon substrate in contact with the Cu nanoparticles. The oxidized silicon then dissolves under the action of HF, causing the Cu nanoparticles to sink. This process forms numerous nanostructures and pore channels on the silicon substrate, effectively exposing the impurities inside the silicon particles and enhancing the removal of impurities from the silicon.

Thanks for the constructive comment, the detailed etching process descriptions of CuACE were provided in the revised manuscript.

9. The conclusion is not unquestionable.

R: Thanks for the kind reminding, we have carefully checked the conclusion parts and they were rewritten and re-organized in the revised manuscript.

Author Response File: Author Response.pdf

Reviewer 3 Report

The research conducted in this study has been poorly organized and presented. It lacks novelty and does not meet the publication standard. The authors have used five different lixiviants to test the leaching behaviors of various metals. In general, leaching is a function of time and acid concentration. Furthermore, different metals behave differently.  Most of the leaching was carried out at a fixed time of 2 hrs without justification. The pH of the system wasn’t given.

The importance of Fig 1 is very questionable. A verbal description of the test samples could be sufficient.

Regarding Table 1, the total content of metals seems to be about 10%. What are the rest and their compositions? What form of compounds are these metals? The authors have assumed they are metallic, but are they pure metals, alloys, etc.?

Fig 2 – Silicon and oxygen seem to be mixed. What fraction of Si is present as SiO2?

The nature and the rationale of the heat treatment of the samples need to be clarified. Was it done in an inert atmosphere or a controlled atmosphere? What was the purpose of the heat treatment? Did metals oxidize during the heat treatment? A more thorough characterization of the sample materials is required before any chemical treatment is affected. There is no indication of the literature on the leaching behavior of these metals and their alloys.

It is unclear what constitutes CuACE, and the chemistry of the reaction of various metals with this reagent needs to be clarified.

In general, figure captions are too brief: no information is given for readers to understand the significance of the data.

Only minor editing is required. 

Author Response

Dear Editor,

Thank you for your effort in evaluating our manuscript and the reviewers’ comments on our paper entitled “Purification of Organosilicon Waste Silicon Powder with Hydrometallurgy”. According to the kind comments, we have revised the manuscript carefully. The revised contents were highlighted by red text in the revised manuscript (marked version).

Our point-by-point responses to the constructive comments are listed below:

1. The research conducted in this study has been poorly organized and presented. It lacks novelty and does not meet the publication standard. The authors have used five different lixiviants to test the leaching behaviors of various metals. In general, leaching is a function of time and acid concentration. Furthermore, different metals behave differently.  Most of the leaching was carried out at a fixed time of 2 hrs without justification. The pH of the system wasn’t given.

R: Thank very much for the referee’s comments on our manuscript which strengthen our manuscript. The goal and novelty of the paper will be explained as follows. Waste silicon powder produced in the production process of organosilicon materials is a major environmental concern that not only leads to pollution but also results in the wastage of resources. As such, it is crucial to find efficient ways of recovering and utilizing this waste material. This paper explores and discusses recycling treatment methods for waste silicon powder, building upon the current state of development in the organosilicon industry. The most effective method for removing impurities from this material is through metal-assisted chemical etching. By developing advanced recycling methods, organosilicon enterprises can reduce environmental pollution, conserve valuable resources, and promote sustainable development.

Leaching is a function of time and acid concentration. Most of the leaching was carried out at a fixed time of 2 h without justification. Sorry for the vague description in the manuscript. We have done a lot of preliminary research on the method of acid leaching. Therefore, the experiments were conducted with the better experimental condition of 2h.

Thanks for the kind reminding. The concentration of acid all reached to molar concentration, and its pH is less than 1, which can't write it in terms of pH. Therefore, the pH of these systems wasn’t given.

2. The importance of Fig 1 is very questionable. A verbal description of the test samples could be sufficient.

R: Thanks for the kind reminding, Fig 1 was revised in the revised manuscript. Besides, the detailed description of the test samples and impurities test methods in silicon were also provided in the Experimental part.

3. Regarding Table 1, the total content of metals seems to be about 10%. What are the rest and their compositions? What form of compounds are these metals? The authors have assumed they are metallic, but are they pure metals, alloys, etc.?

R: Based on testing methods, the concentrations of impurities in waste silicon powder were tested by ICP. It was found that the main impurities are Fe, Cu, Al, Cl, Ti, Ca, and the rest element is Si. However, their compositions can’t be detected by ICP directly, therefore, SEM equipped with EDS was used to further analyze existing forms, and microscopic morphology of the impurities in the waste silicon powders.

Sorry for the vague description in the manuscript, in order to make it easier and clearer for readers to understand our work, we have revised the relevant descriptions in the revised manuscript.

4. Fig 2 – Silicon and oxygen seem to be mixed. What fraction of Si is present as SiO2?

R: Thanks for the kind reminding. Since the silicon content is relatively high and the percentage of SiO₂ content is difficult to detect directly. The oxygen content was tested, which accounts for 11% of the waste silicon powder. By calculating the fraction of SiO₂, which accounts for about 22%.

5. The nature and the rationale of the heat treatment of the samples need to be clarified. Was it done in an inert atmosphere or a controlled atmosphere? What was the purpose of the heat treatment? Did metals oxidize during the heat treatment?

R: Sorry for the vague description in the manuscript. Heat treatment was done for the removal of needle organosilicon in an argon protective atmosphere. The surface of Si particles contained a large amount of needle-like silicon. It was mainly organosilicon attached to the surface of the waste silicon powder and mixed into the waste silicon powder. The needle-like silicon on the surface of the waste silicon powder had a significant reduction after heat treatment. This reduction allows the surface of the powder to open up, making it more conducive to the process of removing impurities. The experimental procedure of high temperature heat treatment includes the weighing of samples, the fixation of the position in a vacuum atmosphere tube furnace, the sealing treatment, the observation after passing argon gas, annealing, the re-weighing of samples. Under argon protective atmosphere, metals usually can’t be oxidized.

Thanks for the constructive comment, we have carefully checked the Experiments parts and they were rewritten and re-organized in the revised manuscript.

A more thorough characterization of the sample materials is required before any chemical treatment is affected. There is no indication of the literature on the leaching behavior of these metals and their alloys.

R: Thanks for the kind suggestions. The Micrograph and mapping analysis of organosilicon waste residue before any chemical treatment was provided in the Support Information and the metals leaching descriptions also cited some literatures in the revised manuscript.

6. It is unclear what constitutes CuACE, and the chemistry of the reaction of various metals with this reagent needs to be clarified.

R: The experimental procedure of Cu-assisted chemical etching was as follows. The experiments were conducted at room temperature and pressure. The samples were dipped into the Cu(NO₃)₂/HF mixture [Cu(NO₃)₂ = 4 mM, HF = 4 M] solution for deposition of Cu nanoparticles (CuNPs) for 60 s, and then 0.5 M H₂O₂ was added to the Cu(NO₃)₂/HF solution, with a leaching time of 2 h.

Thanks for the kind reminding, the detailed leaching procedures of CuACE experiments were provided in the Experimental part.

7. In general, figure captions are too brief: no information is given for readers to understand the significance of the data.

R: Sorry for the vague description in the manuscript, we have carefully revised the figure captions in the revised manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The current version of the paper represents an improvement over the previous one. However, it is important to have the text reviewed by a language specialist to ensure accuracy and clarity. Additionally, the conclusions still remain too general. The authors do not address the issue of silicon waste purity as previously indicated, and it would be valuable for them to provide insight on whether their achieved level of purity is acceptable from an industrial standpoint.

Most of the comments are in the attached file.

Comments for author File: Comments.pdf

The English language in the paper requires further review and improvement. The authors often use repetitive or confusing phrases that hinder the clarity of the message. Therefore, it would be beneficial to revise the text for style and eliminate unnecessary repetitions to enhance the overall readability of the paper.

Author Response

Dear Editor and Reviewer,

Thank you for your effort in evaluating our manuscript and the reviewers’ comments on our paper entitled “Purification of Organosilicon Waste Silicon Powder with Hydrometallurgy”. According to the kind comments, we have revised the manuscript carefully. The revised contents were marked up using the “Track Changes” in the revised manuscript (marked version).  

Our point-by-point responses to the constructive comments are listed below:

The current version of the paper represents an improvement over the previous one. However, it is important to have the text reviewed by a language specialist to ensure accuracy and clarity. Additionally, the conclusions still remain too general. The authors do not address the issue of silicon waste purity as previously indicated, and it would be valuable for them to provide insight on whether their achieved level of purity is acceptable from an industrial standpoint.

R: Thank very much for the referee’s recognition of our work and positive comments on our manuscript which strengthen our manuscript. The conclusions were corrected in the revised manuscript.

1. The concept of experiment. The font size should be increased.

R: Thanks for the kind reminding. The concept of experiment was added and the font size was increased in the revised manuscript.

2. Instead: The SEM and ICP analysis results are highly consistent.

R: Thanks for the kind reminding, we have revised the corresponding sentence in the revised manuscript.

3. The effect of hydrochloric concentration on leaching efficiency (or impurities removal) was examined in this study.

R: Thanks for the kind reminding, we have revised the corresponding sentence in the revised manuscript.

4. When the HCl concentration is lower than 1 M, the removal rate of each major impurity sharply increases with increasing HCl concentration, and then the removal rate of Fe and Cu gently increases with further increases in concentration.

R: Thanks for the kind reminding, we have revised the corresponding sentence in the revised manuscript.

5. room? ambient? give a value.

R: Sorry for the vague description in the manuscript, the value of room temperature was provided in the Experimental part of revised manuscript.

6. This is a shortcut. You can analyse liquid solutions using ICP and get the results after the analysis. or You can analyse ICP results.

R: Thanks for the kind reminding, the corresponding sentence was corrected in the revised manuscript.

7. The English language in the paper requires further review and improvement. The authors often use repetitive or confusing phrases that hinder the clarity of the message. Therefore, it would be beneficial to revise the text for style and eliminate unnecessary repetitions to enhance the overall readability of the paper.

R: Thanks for the kind reminding, the entire manuscripts were carefully revised through a professional language editing service. 

Author Response File: Author Response.pdf

Reviewer 3 Report

The study here represents some interesting leaching behaviors for various metals in silicon powders. However, no chemical reactions but speculations with various acid treatments were given. It lacks scientific novelty but shows various behaviors with different acid treatments.

Unusual acronyms should be avoided in Keywords. For example, MACE is not a household term known in hydrometallurgy.

Some paragraphs, especially in the Introduction, should be shorter for the readers to comprehend the meaning of the text.

In the introduction, progmote – typo?

Leaching experiments were conducted at two hr-period, and some comments on time-dependent behavior should be made. 

The manuscript has been written in good English, but there are too many long paragraphs for the readers to understand the meaning of the text. 

Author Response

Dear Editor and Reviewer,

Thank you for your effort in evaluating our manuscript and the reviewers’ comments on our paper entitled “Purification of Organosilicon Waste Silicon Powder with Hydrometallurgy”. According to the kind comments, we have revised the manuscript carefully. The revised contents were marked up using the “Track Changes” in the revised manuscript (marked version).

Our point-by-point responses to the constructive comments are listed below:

1. The study here represents some interesting leaching behaviors for various metals in silicon powders. However, no chemical reactions but speculations with various acid treatments were given. It lacks scientific novelty but shows various behaviors with different acid treatments.

R: Thank very much for the referee’s comments on our manuscript which strengthen our manuscript. Actually, the removal of impurities from waste silicon powder with hydrometallurgy can be concluded as chemical reaction (1). The impurities are removed though facilitating ionization of themselves with different acid methods.

 (1)

Thanks for the constructive comment, the chemical reactions of impurities removal descriptions were provided in the revised manuscript.

2. Unusual acronyms should be avoided in Keywords. For example, MACE is not a household term known in hydrometallurgy.

R: Thanks for the kind reminding, we have replaced MACE with metal-assisted chemical etching (MACE) in the revised manuscript.

3. Some paragraphs, especially in the Introduction, should be shorter for the readers to comprehend the meaning of the text.

R: Thanks for the kind reminding, we have carefully checked the introduction parts and they some paragraphs in the Introduction were rewritten and re-organized in the revised manuscript.

4. In the Introduction, proqmote – typo?

R: Sorry for the spelling mistake in the Introduction, “proqmote” was revised as “promote” in the revised manuscript.

5. Leaching experiments were conducted at two hrs.-period, and some comments on time-dependent behavior should be made.

R: We have done a lot of preliminary researches on the method of acid leaching, it was found that the trend of impurity removal increased as the leaching time increased and the removal effect of leaching time. Based on the trend of removal rate, it was found that the better removal effect was achieved at the leaching time of 2 hours. Therefore, leaching experiments were conducted at two hrs.-period. However, for lack of space, the leaching time experiments were not shown in the manuscript.

Thanks for the kind suggestion, the comments on time-dependent behavior was added in the revised manuscript.

Author Response File: Author Response.pdf

Round 3

Reviewer 3 Report

The study here represents some interesting leaching behaviors of various metals in silicon powders. 

Minor revision with proper adjustment of long paragraphs.

Author Response

Dear Editor and Reviewer,

Thank you for your effort in evaluating our manuscript and the reviewers’ comments on our paper entitled “Purification of Organosilicon Waste Silicon Powder with Hydrometallurgy”. According to the kind comments, we have revised the manuscript carefully. The revised contents were marked up using the “Track Changes” in the revised manuscript (marked version).

Our point-by-point responses to the constructive comments are listed below:

1. The study here represents some interesting leaching behaviors of various metals in silicon powders.

R: Thank very much for the referee’s recognition of our work and positive comments on our revised manuscript which strengthen our manuscript.

2. Minor revision with proper adjustment of long paragraphs.

R: Thank for the kind reminding, some long paragraphs were adjusted in the revised manuscript.

Author Response File: Author Response.pdf