Processing Tests, Adjusted Cost Models and the Economies of Reprocessing Copper Mine Tailings in Chile
Round 1
Reviewer 1 Report
Review for article: «Processing tests, adjusted cost models and the 3 economic potential for reprocessing copper mine 4 tailings in Chile»
Dear Authors, thanks for the interesting and informative article that shows separation experience and a way to economically evaluate a copper tailings processing project. An early assessment of the efficiency of processing tailings with a low content of useful components is a pressing problem for many companies. Evaluation at the early stages of geological exploration influences the economic results of the future project and complements the evaluation of tailings.
However, I have a few comments:
1.The title of the article includes the concept of "economic potential", therefore, it would be advisable to show in the introduction what you mean by the «economic potential», or remove this term from the title.
2.Introduction. Examples of the experience of extracting copper from tailings are desirable in the introduction. For example, the experience of Russia, where, as in Chile, copper-porphyry deposits prevail and there is a problem of using processing waste. In the absence of similar examples, highlight the uniqueness of the Chilean copper tailings and tailings that are being investigated.
Research methods. Research methods represent a detailed algorithm for collecting and processing samples with a proposal for specific technologies and their economic assessment. My competence is limited to the economic aspects of the proposed approach.
3.Giving a brief description of the methodological approach used for economic assessment would be desirable.
4.If you leave the term "economic potential" in the title of the article, then it is necessary to give the comments of the indicators that are used to assess it.
5.The indicators used for economic evaluation, as well as the limitations and assumptions used in determining the indicators, should be properly justified. It is desirable to present all indicators for economic evaluation in tabular form.
6.Some estimates are conditional (line 442-444 «The chosen daily processing rate of 500 t/d leads to a life of “project” of
around 11 years. Assuming a downtime of 20 % it would be 13.6 years (292 working/processing days per year»). Assumptions and constraints should be clearly described.
- You've done a rough estimate, so I recommend adding a rough estimate of the risks for 3 options: (pessimistic, probable, optimistic)
8.The conclusion recommends adding how this pilot project can be replicated to hundreds of other tailings in Chile.
Comments for author File: 
Comments.pdf
Author Response
Response to reviewer 1
Dear reviewer,
Thank you for the helpful comments. Below you will find my reply.
Comment 1: Changed the title to …and economies of reprocessing …
Comment 2: changes in lines 44-46 and 100-102.
Comment 3: changes 254-287. Too much?
Comment 4: See comment 1
Comment 5: Now it's the economies of reprocessing in general. I hope that is in line with what you wanted me to change?!
Comment 6: deleted
Comment 7: There are now scenarios for ± 10 % copper price and ± 10 % recoverable grade
Comment 8: Tonnage for Fe-reprocessing is given, but I would prefer not to give the tonnage for copper, as the data from the cadaster is taken from superficial samples
Kinde regards,
Malte Drobe
Reviewer 2 Report
This manuscript has discussed different schemes for reprocessing of tailings and adopted a simple economic evaluation tool based on comparative cost models for a first assessment of the viability of reprocessing. The adopted cost models showed positive results at the semi technical scale processing tests. This study is valuable and the manuscript can be considered for publication in journal after minor revisions as below: 1. In the Table 1, “CusO4” should be “CuSO4”. In addition, the form of Table 2, Table 8 and Table 11 need to be centered. 2. Line 82-83, References are necessary to support the statement “For the economic evaluation, several assumptions considering investment costs, operating costs and revenues have to be made”. 3. The Figure 1 is fuzzy. Please improve the image resolution. 4. Why not write down a formula to calculate the cost. 5. To compare different schemes for reprocessing of tailings and cost models more clearly, a section of “3.4 Discussions” can be added before section “5. Conclusion”. In addition, please write it a little bit more concisely.
Comments for author File: Comments.pdf
Author Response
Response to reviewer 2
Dear reviewer,
Thank you for the helpful comments. Below you will find my reply.
Comment 1: changed as suggested
Comment 2: I think this is a misunderstanding. The sentence is about the assumptions made in this paper. I added “…and are discussed in this paper“.
Comment 3: New figure with higher resolution
Comment 4: If so I would have to do that relatively often, which would make the paper even lengthier due to the formula and the explanation of the formula. If you think that it would really help understanding the paper I will off course do so.
Comment 5: New chapter included.
I tried to shorten some parts of the manuscript (see track changes)
Kind regards,
Malte Drobe
Reviewer 3 Report
The topic of the manuscript is of great importance in view of the circular economy paradigm shift and for efficient resource recovery. The manuscript is full of information and the study is much needed for assessing the possibility to recover metals from mine tailings. However, the quality of the English suffers in many instances and I am surprised such errors could have slept in the final manuscript. In my opinion, the manuscript should be revised by authors to increase its quality in terms of English and understanding. Also, I find the presentation lengthy and repetitive, and the number of figures excessive.
I offer several comments below:
L17: unextracted
L35: in 2019 alone
L59: "pure" means theoretical ??
L61: the recovery
L120: experiment
L127: as a consequence
L165-166: rephrase the whole sentence
Fig.3 could very all be transferred to Supplementary material.
L178: at 5m depth
L221: CuSO4
L336: use superscripts when writing chemical formulas
L242: define "low acid concentration"
L252-253: revise the whole sentence
L282: remove "be"
L310: saleable
L312: expanses
etc...the manuscript needs a serious revision.
Author Response
Response to reviewer 3
Dear reviewer,
Thank you for the helpful comments regarding language, length and some repetition. I have gone through the manuscript and I hope I have been able to improve it as expected.
Kind regards,
Malte Drobe
