Evaluation of the Efficiency of Using an Oxidizer in the Leaching Process of Gold-Containing Concentrate

Round 1

Reviewer 1 Report

The manuscript presents the results of centrifugal gravity beneficiation following cyanide leaching of gold-bearing concentrate using a tri-chlorine-cyanuric acid (TCCA) oxidizer. The paper corresponds to the journal profile. On the other hand, the paper doesn't describe the comparison with your experimental results. There are a lot of flaws in this manuscript which prevents it from being recommended for publication.

1-In Abstract; authors said that “Microscopic studies have established the presence of gold grains in free form, ranging in size from 0.9-10.2 mkm Au-ultrafine and fine gold.     Since pyrite in technogenic raw materials is the main gold-containing mineral, …”. If it contains free gold grains, why is it considered cyanide? Also, what do gold grains in pyrite mean if there are free gold grains? These expressions need explanation.

2- In page 2, lines 91-92; authors said that “The process of bacterial leaching in relation to gold-containing raw materials is widely used in the world practice and is the most environmentally friendly method of processing compared to other methods”. This is not correct information. Bacterial leaching is much less common in the world than other leaching processes, and studies are generally carried out on a laboratory or pilot scale. If there were many applications of this subject in the literature, they would give references.

3- In page 3, lines 121-122; authors said that “There is little information in the literature about the use of organic chlorides for opening gold from iron sulphides”. Are the gold grains free or contained in pyrite?

4-The authors used centrifugal-type separators (Falcon or Knelson), but why do they grind the ore below 50 microns even though these devices are known to be inefficient below 50 microns?

5- The authors say they used centrifugal-type separators (Falcon or Knelson) in Figure 11. However, although these separators are known to be inefficient below 75 microns, why do they grind ore below 25 microns? Also, the authors should have shown the centrifugal-type separator they used as a photograph in the manuscript.

6- It appears that the authors conducted zeta potential studies. Zeta potential studies are used to elucidate the adsorption mechanism for physicochemical concentrations, such as the flotation of minerals. However, no flotation study was performed in this study.

7- In page 6, lines 217-222; gold content are 4 ppm to +0.2 mm sieve size, 1.3 ppm to -0.2+0.1 mm sieve size, 1.25 ppm to -0.1+0.07 mm sieve size, 1.32 ppm to -0.07+0.05 mm sieve size, 0.59 ppm to -0.05+0.0 mm sieve size. From here, since the 55.64% remaining above 50 microns has an average gold content of 1.75 ppm, wouldn't it be more logical to acquire the ore separately? Especially considering the grinding cost and slime problem in the gravity concentration, why was the ore unnecessarily ground below 50 microns? It is impossible to understand this situation.

8-Table 1 gives the X-ray phase analysis of the starting ore. However, providing a graph containing the main XRD 2ɵ values would be much more meaningful.

9- In page 9, lines 295-296; authors said that “Therefore, under the action of TCCA solution with a concentration of 2-2.5 g/l at pH 6 for 3-5 hours, the following reactions can occur without air purging”. Cyanide (CN) completely transforms into HCN gas below pH 8.5. How come cyanide is processed at pH 6? This is a very illogical situation.

10-The industrial benefit of this study is not mentioned.

11-Grinding test conditions were not described sufficiently.

12-Some grammatical corrections need to be made, and the authors need to re-read the article carefully to eliminate spelling errors. Even the title of the manuscript ("Evalution" instead of "Evaluation") has a typo.

13- There are similar studies in the literature. The current paper does not contribute anything new in this respect. The lack of any explanations to challenge or confirm existing ideas leads to a low overall contribution to the scientific field.

Some grammatical corrections need to be made, and the authors need to re-read the article carefully to eliminate spelling errors. Even the title of the manuscript ("Evalution" instead of "Evaluation") has a typo.

Author Response

Thank you very much for taking the time to review this manuscript. Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The article describes a method for advanced gold recovery from mature tailings from one deposit in Khazahstan which was not studied for concentrability yet. The method with cyanide was improved with enrichment of tailings in a centrifugal separator and with oxidation of pyrite with TCCA prior to the cyanide treatment. A recovery grade over 80% was obtained.

In some points of the manuscript, some corrections are needed:

-        In the Abstract, please use the SI symbol for micrometer : μm instead of mkm.

-        Please re-number references in order. In your text, reference 31 is cited immediately after reference 5, 32 after 11, etc.

-        It is not clear if the statement from page 2, lines 57-59 belongs to reference 5 or to reference 31.

-        Page 2, lines 94-97: which is the reference for this statement?

-        Page 3 line 104: what is “vapor elasticity of the solution”? Vapor pressure, maybe.

-        Page 3, lines 113-114 : “a high rate of mass transfer of oxygen in the reaction mass” instead of “ a high rate of mass transfer of oxygen in the reactor”.

-        Page 3, line 125: references [24-25-25]?

-        Page 3: the symbol of chlorine is Cl, not CI. You used wrongly CI (carbon-iodine) all over the chemical reactions and somewhere in the text (e.g. page 3, lines 134-135).

-        Page 3, line 135: what means 3.5,₂ ?

-        If Figure 1 is taken from a source in literature [2,3?] you should ask permission from the respective journal to reproduce it here, and the source should be cited.

-        Table 1- What means S-Q? you should explain. Content? Is it expressed in %?

-        Table 2- What contains the rest to 100%? Please explain.

-        Page 6, lines 217-222- what analysis was employed for the distribution of gold size? The below mentioned sieve analysis? If so, please mention first the analysis method and then the results.

-        Page 6, line 224:”Samples of the samples”? Simply: “Samples were placed…”

-        Page 10, line 299: What program have you used for Gibbs energy calculation? Name it.

-        Page 10, line 324: What “well known program” did you use? Name it.

-        Page 10, line 325: What is “ Пwhen”?

-        Page 11, line 331:”The ROP of solution correlates with the rate of pyrite dissolution (Figure 9)”. As seen in Figure 9, on the x-axis is the TCCA molar concentration, not “the rate of pyrite dissolution”.

-        Page 11, Figure 10: The legend is incomplete, only concentrations 4.3 and 8.6 mmol/l appear in the legend.

-        Page 12 , lines 354-355: please reformulate “acceleration of the gravitational fall of 90^oC”(incomprehensible)

-        Page 12 line 367 and p.13, line 406: 6.41% instead of 6.39%, according to Table 3.

-        The last section Discussion is in fact Conclusions. Section 3 should be named “Results and discussion” and Section 4. Conclusions.

Minor corrections and reformulations are needed.

Author Response

Thank you very much for taking the time to review this manuscriptPlease see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript with the title of “Evalution of the efficiency of using an oxidizer in the leaching process of gold-containing concentrate” presents the work of Authors in obtaining an increase of 5.8% in the gold recovery by pretreating gold tailings sample with trichlorocyanuric acid (TCCA) oxidizer.

Authors need to present the writing in a systematic way for readers to be able to catch the idea of the work. For example, it is difficult to picture the experimental steps in the Section 2. Materials and Methods

Avoid using hyphens in the manuscript writing.

The XRD and X-ray fluorescence graphs should be inserted in the manuscript.

What is S-Q in Table 1 should be clearly defined?

A comparison with the latest literatures is necessary in the Results and Discussion

Since it is a research paper, the manuscript should be ended with conclusion not discussion.

Author Response

Thank you very much for taking the time to review this manuscriptPlease see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors seem to have responded to my critical comments on the current manuscript and eliminated the necessary deficiencies

Author Response

Thank you very much for taking the time to review this manuscript. All the links given are relevant to the research. The links were formatted.

Reviewer 3 Report

Authors have replied to all the comments forwarded in the first review.

Authors need to improve the clarity of the legends in all Figures.

Moderate editing of English language required

Author Response

Thank you very much for taking the time to review this manuscript. Improved the clarity of some Figures.