Incidence of Electric Field and Sulfuric Acid Concentration in Electrokinetic Remediation of Cobalt, Copper, and Nickel in Fresh Copper Mine Tailings

Round 1

Reviewer 1 Report

The manuscript titled "Incidence of Electric Field and Sulfuric Acid Concentration in 2 Electrokinetic Remediation of Cobalt, Copper, and Nickel in 3 Fresh Copper Mine Tailings" was thoroughly reviewed and it is recommended to be recheked for the English language. Some sentences are too long and need to be rephrased for better comprehension.

Author Response

The manuscript titled "Incidence of Electric Field and Sulfuric Acid Concentration in 2 Electrokinetic Remediation of Cobalt, Copper, and Nickel in 3 Fresh Copper Mine Tailings" was thoroughly reviewed and it is recommended to be recheked for the English language. Some sentences are too long and need to be rephrased for better comprehension.

We agreed with you, and a complete grammar check was made throughout the article to achieve a better comprehension.

Reviewer 2 Report

 

1. The operating parameters effects should be discussed i.e. current density, pH, residual content, cumulative outflow and time to critically assessing the EKR experiments.

2. Why copper was not removed in this EKR study although literature reports confirm copper removal in other different EKR studies. References and justification needs to be provided.

3 Rather than statistical conclusions technical inferences and technical outcomes of study must be provided in discussion and conclusions along with effect of physical and electrical operational parameters.

Author Response

1. The operating parameters effects should be discussed i.e. current density, pH, residual content, cumulative outflow and time to critically assessing the EKR experiments.

pH, current density and operation time were discussed deeper in lines 101-106 and pH values at trials beginning were added to Table 2.

2. Why copper was not removed in this EKR study although literature reports confirm copper removal in other different EKR studies. References and justification needs to be provided.

A better understanding and references about this difference were written in lines 286-293. Principal difference is copper solid phase (sulphide or sulphate), which impacts in metal solubilization, therefore, in its availability in liquid phase.    

3 Rather than statistical conclusions technical inferences and technical outcomes of study must be provided in discussion and conclusions along with effect of physical and electrical operational parameters.

Technical outcomes and inferences were added throughout discussions and conclusion.

Reviewer 3 Report

The intro is not well written. It is therefore recommended to revise the introductory part by including the system advantages. Why is controlled backfilling the need of the hour? Current system production quantity?? Common techniques used to manage? Why is mathematical modeling necessary? Add previous literature in your introduction with similar studies? Please add the novelty at the end of the introduction instead of describing it separately.

-     The evaluated numbers should be rounded to make them real.

 

-     The abstract is very vague and should be revised.

-Conclusion should be revised by incorporating best results of study

-References should be updated by including some previous references

-Include some references from processes journal

 

Author Response

The intro is not well written. It is therefore recommended to revise the introductory part by including the system advantages. Why is controlled backfilling the need of the hour? Current system production quantity?? Common techniques used to manage? Why is mathematical modeling necessary? Add previous literature in your introduction with similar studies? Please add the novelty at the end of the introduction instead of describing it separately.

We appreciate the comment and expand o explained better the introduction. Regarding your questions, these are the answers we added in the manuscript.

System advantages: Lines 49-54. It can remove potentially profitable species (metals) regardless its initial concentration, can be applied in situ and have a minor impact in tailing dams.

Backfilling control importance: lines 40-42. Mining waste disposal methods are being revised in aim to make it sustainable.

Production quantity: lines 54-55. Remediation market is around US$30 billion worldwide.

Common techniques to manage: lines 42-49. EKR competition are soil flushing, phytoremediation and bioremediation.

Need of mathematical treatment: lines 69-72. These methods provide reliable conclusions with a control in data error.

Add more literature with similar studies: literature with studies using Chilean mine tailings were added.

• Jensen, P.E.; Ottosen, L.M.; Hansen, H.K.; Bollwerk, S.; Belmonte, L.J.; Kirkelund, G.M. Suspended electrodialytic extraction of toxic elements for detoxification of three different mine tailings. Int. J. Sustain. Dev. Plan. 2016, 11(2), 119-127. DOI: 10.2495/SDP-V11-N2-119-127.
• Hansen, H.K.; Rojo, A.; Ottosen, L.M. Electrodialytic remediation of copper mine tailings. J. Hazard. Mater. 2005, 117(2–3), 179-183. DOI: 10.1016/j.jhazmat.2004.09.014.
• Rojo, A.; Hansen, H.K.; Ottosen, L.M. Electrodialytic remediation of copper mine tailings: Comparing different operational conditions. Miner. Eng. 2006, 19(5), 500-504. DOI: 10.1016/j.mineng.2005.08.016.

 Novelty: lines 69-72. EKR experiments in Chilean copper mine tailings never registered the behavior of cobalt or nickel, and regarding to copper, this statistical approach was never used throughout the entire cell.

-     The evaluated numbers should be rounded to make them real.

We do not understand this comment completely, but we inferred that you expected a better homogeneity in delivered numbers about decimal digits, so we delivered every calculated number with two decimal digits. If it this was not what you meant, please let us know.

 -     The abstract is very vague and should be revised.

Abstract was revised and best concentration results were added, including best operating conditions which originated them.

-Conclusion should be revised by incorporating best results of study

Conclusions were written in the first case with the best results, but it was not clear in discussions. This was rewritten in lines 280-284. Nevertheless, conclusion was revised to expand the results.

-References should be updated by including some previous references

These are some of the references that were added, besides those presented in other questions:

• Araya, N.; Mamani Quiñonez, O.; Cisternas, L.A.; Kraslawski, A. Sustainable Development Goals in Mine Tailings Management: Targets and Indicators. Mater. Proc. 2021, 5(1), 82-88. DOI: 10.3390/materproc2021005082.
• Aznar-Sánchez, J.A.; García-Gómez, J.J.; Velasco-Muñoz, J.F.; Carretero-Gómez, A. Mining Waste and Its Sustainable Management: Advances in Worldwide Research. Minerals 2018, 8, 284. DOI: 10.3390/min8070284.
• Acar, Y.B.; Gale, R.J.; Alshawabkeh, A.N. ; Marks, R.E.; Puppala, S.; Bricka, M.; Parker, R. Electrokinetic remediation: basics and technology status, J. Hazard.Mater. 1995, 40, 117-137. DOI: 10.1016/0304-3894(94)00066-P.
• Alshawabkeh, A.N. Electrokinetic soil remediation: challenges and oportunitites, Sep. Sci. Technol. 2009, 44 2171-2187. DOI: 10.1080/01496390902976681.
• Singh, A., Kuhad, R.C., Ward, O.P. Biological Remediation of Soil: An Overview of Global Market and Available Technologies. In: Singh, A., Kuhad, R., Ward, O. (eds) Advances in Applied Bioremediation. Soil Biology, vol 17. Springer, Berlin, Heidelberg, 2009. ISBN: 978-3-540—89621-0.
• Chen, R.; Zhou, L.; Wang, W.; Cui, D.; Hao, D.; Guo, J. Enhanced Electrokinetic Remediation of Copper-Contaminated Soil by Combining Steel Slag and a Permeable Reactive Barrier. Appl. Sci. 2022, 12, 7981-7993. DOI: 10.3390/app12167981.
• Ge, X.; Xie, J.; Song, X. ; Cao, X. ; Wang, Y. ; Xu, Z. Electrokinetic Remediation of Cadmiun (Cd), Copper (Cu) and Nickel (Ni) Co-contaminated soil with Oxalic Acid, Acetic Acid or Citric Acid as a Catholyte. Int. J. Electrochem. Sci. 2022, 17, ArticleID: 220444. DOI: 10.2064/2022.04.48.

-Include some references from processes journal

These were the references added specifically from this journal. As can be seen in last question, another MDPI journal articles were added to the references.

• Qin, J.; Zhao, H.; Dai, M.; Zhao, P.; Chen, X.; Liu, H.; Lu, B. Speciation Distribution and Influencing Factors of Heavy Metals in Rhizosphere Soil of Miscanthus Floridulus in the Tailing Reservoir Area of Dabaoshan Iron Polymetallic Mine in Northern Guangdong. Processes 2022, 10, 1217-1231. DOI: 10.3390/pr10061217.
• Tarfeen, N.; Nisa, K.U.; Hamid, B.; Bashir, Z.; Yatoo, A.M.; Dar, M.A.; Mohiddin, F.A.; Amin, Z.; Ahmad, R.A.; Sayyed, R.Z. Microbial Remediation: A Promising Tool for Reclamation of Contaminated Sites with Special Emphasis on Heavy Metal and Pesticide Pollution: A Review. Processes 2022, 10, 1358-1384. DOI: 10.3390/pr10071358.