Recovery of Tellurium from Waste Anode Slime Containing High Copper and High Tellurium of Copper Refineries

Round 1

Reviewer 1 Report

The development of the solar and electronics industries has caused a steady increase in the demand for tellurium, and the global demand for tellurium is met by recovering tellurium from the anode slime produced during the electrolytic purification of copper. A process for producing pure element tellurium from waste anode slime with high copper content has been developed. The anode slime was treated by leaching, roasting and electrodeposition to produce elemental tellurium and copper. Best suggested conditions for sample due to economic reasons is air roasting at 450°C without any soda followed by leaching under the conditions: 1M NaOH, 10% pulp density, 2 h. In this process, the recovery rate of the metal is as high as 90%, and the purity of the obtained tellurium metal is as high as 99.99%, which has sustainable energy prospects. However, this paper needs some revisions to improve its quality for publication. Authors should answer the following questions.

Question 1: The first two paragraphs of the introduction lack references and could be further supplemented in order to add credibility to the article.

Question 2: In the leaching experiments, the authors chose to use an oxygen pressure of 2 kg/cm² and a leaching time of two hours, whether these two sets of data could be further optimized to improve the recovery of Tellurium.

Question 3: The conclusion section could be enriched by adding some future perspectives and some shortcomings of this study. What’s more, the economic analysis of other processes is mentioned in the introduction part of the article, and the economic evaluation of this process can be added in the conclusion part.

Question 4: The format of the tables needs to be standardized. All tables in the article should use three-line tables and the text should be centred.

Question 5: The concentration units in the figure notes of the article should be standardised, for example from g/l to g/L.

Question 6：Reference 16 in the article is incorrectly numbered and should be reordered.

Question 7：The use of punctuation in the article needs to be standardized, for example, the lack of periods in the last two sentences of the abstract.

Question 8：The step of leaching the anode slime needs to be more specific. 

English is OK

Author Response

The author's responses to the reviewer's queries are given in the attached word document.

Author Response File: Author Response.pdf

Reviewer 2 Report

Tellurium exhibits enhanced electrical conductivity essential for an efficient photovoltaic solar cell and improves machinability without altering the conductivity when it is added to steel, copper, and lead alloys. Tellurium is primarily a by-product recovered at copper refineries due to which specific domestic and international tellurium sources are unknown. Therefore, the sustainable development of efficient tellurium production and recovery processes as well as assessing of commercially exploitable tellurium resources are essential to meet the worldwide demand. Considering the steady growth in tellurium demand as a result of the rise in solar energy and the electronic industry, herein Chinmaya Kumar Sarangi et al. developed optimum conditions to recover Te and Cu from anode slime having the composition of Cu: 31. 8%, Te: 24. 7% and As: 0. 96%. The purity of Te metal achieved was up to 99.99%, which is a sustainable energy future. The proposed method for recovery of Te from anode slime seems to be efficient, and reliable. The manuscript is of wide interest and it would be a good reference for the researchers working in the fields of chemical engineering, environmental engineering, energy engineering and separation science. Nevertheless, there are some technical issues and a major revision is required.

The following points are important for improving the quality, logic, completeness, reliability and readability of the manuscript and therefore they should be well addressed and included in a revised version of the manuscript.

(1) In Lines 39-53, some data, for instance, "processing 500 tons of copper ore usually produces 1 pound (0.45 kg) of tellurium" and "it is usually observed that the processing of 1000 tonnes of copper ore produces 1 kg of tellurium", were used but their sources (or references) were not given. Please add them to the text for easy understanding.

(2) From Line 20 to Line 39, the authors introduce some applications of Tellurium compounds. However, no one related literature was cited. Some related papers should be cited to exemplify  several applications. For instances, Bismuth Telluride is used as thermoelectric generators [see: Shen, H.; Kim, I.-Y.; Lim, J.-H.; Cho, H.-B.; Choa, Y.-H. Microstructure Evolution in Plastic Deformed Bismuth Telluride for the Enhancement of Thermoelectric Properties. Materials 2022, 15, 4204. https://doi.org/10.3390/ma15124204]. Tellurium as ZnCdTe is utilized in radiological sensors [see: Borbinha, J.; Romanets, Y.; Teles, P.; Corisco, J.; Vaz, P.; Carvalho, D.; Brouwer, Y.; Luís, R.; Pinto, L.; Vale, A.; Ventura, R.; Areias, B.; Reis, A.B.; Gonçalves, B. Performance Analysis of Geiger–Müller and Cadmium Zinc Telluride Sensors Envisaging Airborne Radiological Monitoring in NORM Sites. Sensors 2020, 20, 1538. https://doi.org/10.3390/s20051538]. In addition, the tellurium compounds are also used as electrode materials of metal-ion batteries [see: Yu, Y.-X. High Storage Capacity and Small Volume Change of Potassium-Intercalation into Novel Vanadium Oxychalcogenide Monolayers V2S2O, V2Se2O and V2Te2O: An Ab Initio DFT Investigation. Appl. Surf. Sci. 2021, 546, 149062. https://doi.org/10.1016/j.apsusc.2021.149062]. At least above representative literatures for Te applications should be cited in the Introduction section.

(3) The last sentence of Abstract (Line 24) and Line 225, " The major impurities contamination of the cathode ...". How did "the cathode" come? What is its meaning here?

(4) The data in Figure 2 have been reported in Table 4, and therefore, Figure 2 should be deleted to avoid needless duplication (and the manuscript is too long).

(5) There are some minor errors such as improper format and representation in the main text. <i> Line 54, " Petteri Halli et al" should be corrected to " Halli et al."; Line 58, " Kang-In Rheea et al" should be corrected to " Rheea et al. "; Line 59, " Xuejie Yue et al " should be corrected to "Yue et al."; Line 60, " Dong Li et al " should be corrected to "Li et al.", and so forth. Please corrected all of this type of format errors. <ii> Line 171, " some decrease in recovery was observed may be..." should be corrected to " some decrease observed in recovery may be...". <iii> Line 158, " the next set of..." should be corrected to ". The next set of ..." <iv> Full stop "." was missing in some sentences and please add it to the corresponding sentences.

(6)The format of the references in the Reference List does not match that of the journal. For examples, the first three references should be listed as

1. Halli, P.; Wilson, B.P.; Hailemariam, T.; Latostenmaa, P.; Yliniemi, K.; Lundström, M. Electrochemical Recovery of Tellurium from Metallurgical Industrial Waste, J. Appl. Electrochem. 2020, 50, 1. https://doi.org/10.1007/s10800-019-01363-6

2. Rheea, K.-I.; Lee, C. K.; Hab, Y.C.; Jeong, G.-J.; Kim, H.-S.; Sohn, H.-J. Tellurium Recovery from Cemented Tellurium with Minimum Waste Disposal. Hydrometallurgy, 1999, 53, 189. https://doi.org/10.1016/S0304-386X(99)00044-4

3. Yue, X.; Chen, H.; Zhang, T.; Qiu, Z.; Qiu, F.; Yang, D. Controllable Fabrication of Tendril-Inspired Hierarchical Hybrid Membrane for Efficient Recovering Tellurium from Photovoltaic Waste. J. Cleaner Production 2019, 230, 966. https://doi.org/10.1016/j.jclepro.2019.05.141

Please revised the format of all references in the Reference List according to above format.

A minor revision on English language is required.

Author Response

The author's responses to the reviewer's queries are given in the attached word document.

Author Response File: Author Response.pdf

Reviewer 3 Report

§  The language in the paper throughout needs to be revised in terms of grammatical and typological errors, to meet the international standard of the journal. Some of the sentences were very long. Also, some words were repeated in two consecutive sentences.

§  The abstract of the article was incomplete and lacked important information. Even in the introduction section, the basis of the work was not explained completely.

§  The core area of this research article is leaching and separation, but the using of this agent is repetitious and has been discussed in many studies. There is much information in this case and there seems to be no innovative idea in this paper. Besides this, the optimum leaching condition was not considered. There was not any discussion about this subject. Also, the recovery of other metals was not seen in the suggested flowchart.

§  The reason for some fluctuation in recovery rate must be properly explained carefully. It would have been better if the chemical structure of the components was analyzed.  

§  The introduction could improve by adding new site literature same as:

Hosseinipour, Seyedreza, Eskandar Keshavarz Alamdari, and Nima Sadeghi. 2022. "Selenium and Tellurium Separation: Copper Cementation Evaluation Using Response Surface Methodology" Metals 12, no. 11: 1851. https://doi.org/10.3390/met12111851

The language in the paper throughout needs to be revised in terms of grammatical and typological errors, so as to meet the international standard of the journal. Some of the sentences were very long. Also, some words were repeated in two consecutive sentences. 

Author Response

The author's responses to the reviewer's queries are given in the attached word document.

Author Response File: Author Response.pdf

Reviewer 4 Report

Sarangi et al. wrote a manuscript about the recovery of Te from anode slimes. The manuscript, in its current state, it is challenging to follow. The following contains a list of questions that should be answered before considering the manuscript for publication.

1. What is the exact source of anode slime? Where was it purchased from?

2. A list of materials is missing from the experimental section. All chemicals used in the study should be stated together with their purity.

3. Lines 102-104 do not contain the specific temperature, pressure, etc. used for the leaching.

4. Lines 113-114, "is completely free from alkali" - How was this determined? pH measurement?

5. Lines 115 - How was the current efficiency determined?

6. The introduction and experimental section gave the impression that this is a electrolytic cell type of reaction. Eq. 1 looks like a solid state reaction, i.e., water is only produced. Is the NaOH dissolved in water?

6. None of the figures and tables have error bars. Have the results been done in triplicate? If yes, what is the standard deviation or the confidence interval? 

7. How was Te purity measured?

8. How was Te recovery measured? There are no details in the experimental section. Is this done by AAS?

9. Line 274: "Sample 2 responded differently towards Te extraction." - What is the explanation behind it? 

10. Line 279: "Best suggested conditions for Sample 2 due to economic reasons is air roasting at 450 ºC" - Was there an economical analysis done? How was this conclusion reached?

Author Response

The author's responses to the reviewer's queries are given in the attached word document.

Author Response File: Author Response.pdf

Reviewer 5 Report

Authors have provided a method to obtain high purity Te from waste anode slimes. However, they should do a thorough comparison of their process and data to other procedures available in literature. 

Comments for author File: Comments.pdf

Overall, English writing can be improved in introduction section by combining small sentences. 

Author Response

The author's responses to the reviewer's queries are given in the attached word document.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors have revised their manuscript by considering all comments and suggestions from Reviewers. The authors have added the data-source related literature in the Introduction section of the revised manuscript. The needless duplication in Figure 2 has been deleted by the authors in the revised version of the manuscript. All the necessary modifications of the sentences and discussion have been included in the revised version of the manuscript. The format of the references has also been corrected in the revised the manuscript. Now the revised manuscript is good enough for publication and I would like to recommend the current form of the manuscript for publication in Sustainability.

In addition, I intentionally remind the author that a table should be arranged on the same page.

Please revised all "et al" to "et al.". For instance, Line 40, Page 2: "Halli et al" should be corrected to "Halli et al.".

Author Response

The author's responses to the reviewer's queries are given in the attached Word document.

Further to this, we have also addressed the editorial comments.

Some related references are suggested to be reviewed. e.g.

• Sb release characteristics of the solid waste produced in the antimony mining smelting process.
• Leaching and Releasing Characteristics and Regularities of Sb and As from Antimony Mining Waste Rocks.
• Antimony Ore Tailings: Heavy Metals, Chemical Speciation, and Leaching Characteristics.
• Effects of redox potential on soil cadmium solubility: Insight into microbial community

Please include these.

• In the revised version of the manuscript, the above-suggested references are included with the corresponding inclusion of text in the introduction section. These references are stated as [17-20].

Furthermore, with respect to other metals such as antimony, arsenic, and cadmium, leaching and releasing studies have been reported by several authors [17–20], which is summarised briefly in this section. Antimony release characteristics of blast furnace slag, mining waste rock, and tailing sand were investigated in static immersion and dynamic leaching tests by Ren et al. [17] and they concluded that the Sb release capacity of the three samples was in descending order of tailing sand, blast furnace slag, and mining waste rock. Zhang et al. [18] studied the leaching and releasing characteristics and regularities of antimony and arsenic from antimony mining waste rocks, blast furnace slags, and tailings. It was suggested that a lower solid-liquid ratio and small particle size improve the leaching efficiency. The concentration of heavy metals, chemical speciation, and leaching characteristics of antimony ore tailings was analyzed by Zhou et al. [19]. The results show that the concentrations of Sb, As, and Hg in the leachates increased with increasing solid-liquid ratio, decreasing particle size, and increasing temperature. Meng et al. [20] aimed to identify the microbes involved in regulating Cd solubility and reveal possible mechanisms. It has been reported that anaerobic microbes, such as anaerolineaceae played an important role in shaping the microbial community in soil and regulating the Cd solubility.

• Moreover, the number of words in the manuscript has been revised and the content has been made up to 4,000 words.

Author Response File: Author Response.docx

Reviewer 3 Report

It seems that the authors of the article have fully answered the referee's requests.

Minor editing of the English language required.

Author Response

Many thanks for your comments.

Reviewer 4 Report

The paper can be published in its current state.

Author Response

Many thanks for your positive response.

Reviewer 5 Report

Authors have taken into account my recommendations and have improved the manuscript.

Author Response

Many thanks for your comments.