Effects of Various Precipitants on Iron Removal from a Zinc Concentrate Pressure Leaching Solution

Round 1

Reviewer 1 Report

Reviews for a manuscript entitled "Removal of iron present in the pressure leaching solution of zinc concentrates". The manuscript is generally well written and it comprise good merits in terms of wastewater management and minimization of ecological footprints. However, there are few areas of improvement to be considered before the manuscript could be accepted for publication.

• Kindly add "and between MgO and hydrated lime. In the abstract.
• The abstract lacks the results. Incorporate the results and clear overview of the most important highlight of the manuscript.
• The main was not emphasized in the abstract. The authors should consider the following chronology: Brief introduction, objective, methodology, results, and conclusions including future work. 
• Performance in terms of % removal for individual alkaline agent need to be included in the abstract. E.g 60%, 50%, etc. for CaO, MgO,...etc, respectively.
• The objectives need to be emphasized. The study is very interesting but re-organisation of the facts is needed. 
• Add more keywords. Atleast 5 - 7. 
• Refer to: Comparison of mine water neutralisation efficiencies of different alkaline generating agents and Fractional and step-wise recovery of chemical species from acid mine drainage using calcined cryptocrystalline magnesite nano-sheets: An experimental and geochemical modelling …. and Co-treatment of acid mine drainage and municipal wastewater effluents: Emphasis on the fate and partitioning of chemical contaminants. This will enhance the technical approach towards the study. 
• Adding PHREEQC geochemical modelling to enhance the simulation will also go a long way in crystallizing the facts. 
• Put page and line numbering for easy reference. 
• Grammar and language need to be checked. 
• Supersaturation and under-saturation could be confirmed by PHREEQC. 
• Table 1: How does SEM determine the mineralogical composition and what is the form of the concentrate?
• Materials and methods need to be re-engineered. Sampling, characterisation, optimisation, etc.
• Quality control need to be emphasized.
• Combine the effect of different alkaline agents into one for easy comparison. pH and all reagents in one Figure and Fe and all regaents in one figure. 
• Characterisation such as XRD and SEM should be on its own section not mixed.
• High percentage of solids with 87% and MgO has higher recovery. Kindly support. Sludge rich in what?
• Figures need to be merged.
• Adding the economics will make this study more interesting.
• Kindly refer to the recommended papers for more insights. 

Author Response

Dear 

Here attached you the answers to your comments and suggestions

Best regards

Claudio Leiva

Author Response File: Author Response.pdf

Reviewer 2 Report

In the present form, this manuscript is not a research paper. Detailed experimental works are seen to be performed. But, under the light of previous works, discussion on experimental findings is not made in the text.

Originality of the work is not stated clearly. Novelty of the study is not stated. Contribution to the scientific knowledge in the related field is not highlighted.

Logic sequence could not be seen especially in the first section. The manuscript is recommended to be rewritten.

Some figures are not informative.

Author Response

Dear

Here attached you the answers to your comments and suggestions.

Best regards

Claudio Leiva

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Accept. Satisfied

Author Response

Dear Reviewer

Thanks for your comments

Best Regards

Claudio Leiva

Reviewer 2 Report

Appreciable data is given in the manuscript. This study is thought to be prepared as a technical report and/or techno-economic analysis for a company. Contribution to science should be emphasized to define it as a scientific work.

There are several confusing points in the presentation of experimental findings. For example: Page 11, line 374-377: what is the measure for defining “best performance”?

Figure captions are not informative. Vertical scale of graphs should be adjusted properly for clean demonstration of experimental findings.

Originality and novelty?

English needs thorough revision.

Author Response

Dear Reviewer

Here attached you our responses.

Best regards

Claudio Leiva

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report

Manuscript is seen to be improved.

In a scientific paper, experimental findings are discussed referring to previously published research works, unknown is stated, and contribution of the present work to the scientific knowledge in the related field is emphasized.

In the section “3. Results and Discussions” of the paper, experimental findings are presented almost without discussions. Only a few works are referred in this section (given below) in such an extensive study. But, those references are seen to be used almost only to compare data.

Line 302: The leaching solutions have Zn contents between 30 g/L and 71 g/L and Fe concentrations between 5,000 mg/L and 23,000 mg/L, with Fe total/Zn mass ratios between 0.1 and 0.5. Table 3 presents the characterization of a solution sample obtained from the concentrate leaching process [2].

WHY DO YOU REFER THESE LINES TO [2]?

Line 361: The aqueous dissolution of MgO is a slow process [36]

WHY?

Line 464: Wang et al. [37] used mechanically activated CaCO3, which favored the increase of its solubility and reactivity.

WHAT IS YOUR CONTRIBUTION? WHAT IS THE DIFFERENCE BETWEEN YOUR WORK AND PREVIOUS ONE?