Bioleaching of Pyrrhotite with Bacterial Adaptation and Biological Oxidation for Iron Recovery
Round 1
Reviewer 1 Report
Typos
page 3 line 113
“….the bacterial culture was were enriched by culturing:..”
Line 125
“…of 20 mesh sieved pyrrhotite sample particles (20 mesh sieved).”
Content questions
Page 2 paragraph 2.1
How did you measure the Zeta potential of ore? Do you use any equipment?
Page 5 fig. 4
I am surprised that the consortium consists of 3 strains. I expected a higher variety of microorganisms.
Page 7 paragraph 3.3
Eh develops differently to the Eh of adaptation. The pH in both experiments is the same
Overall remarks
There are no results that prove the general thesis from abstract: Bacteria can better attach to the positive charged ore surface at pH lower than 3. Nowhere any counts or pictures of bacteria on ore surface. Support your thesis by defining the surface charge or Zeta potential of bacterias at different pH. The pH in experiments with ore is higher than 3. That means the ore is negatively charged. Why do you believe that the bacteria attach to the mineral surface? Proof it by experimental data. The novelty will rise if you proof that the adaptation changes the Zeta potential of microbial cells and therefor the attachment bevavior.
Author Response
Thanks for your comment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Bioleaching of pyrrhotite with bacterial adaptation and biological oxidation for iron recovery
Bong-Ju Kim, Yong-Kwon Koh, Jang-Soon Kwon
My comments:
1.
16 bioleaching under different initial pH conditions (2.8 and 3.2). Negatively charged bacteria could be
Should be initial pH (pHini) subscript
18 PZC (3.0). Under bacteria-adapted conditions, the leaching concentration of Fe (44.2 mg/L) at pHini
pHini 19 of 2.8 was 2.1 times greater than that (21.3 mg/L) at pHini pHini of 3.2
2.
33 ….. Currently, the bi-
34 oleaching method is attracting interest as an alternative method due to its environmental 35 friendliness and cost effectiveness.
note / reference to a word currently-
the method has been known since the dawn of metallurgy:
“The Rio Tinto mines in South-Western Spain are usually considered as the cradle of biohydrometallurgy. These mines have been exploited since pre-Roman times for their copper, gold, and silver values. However, with respect to commercial bioleaching operations on an industrial scale, biohydrometallurgical techniques were introduced to the Tharsis mine in Spain earlier.”
70 oxidation on bioleaching efficiency at different pHs using (non-) adapted indigenous bac
71 teria.
non-adapted and adapted or non and adapted
94 the indigenous microbes existing in mine drainage (pH: 4.62 and Eh: 365 mV) located at
Eh (Redox potential)
95 which was 82 m under the ground at the Ul-Jin Mine cave, and The microbes were cul
The
135 where E is the leaching concentration at time t, EI is the maximum leaching concen
EI subscript
141 Jin Fe mine contained 5670 mg/kg of Fe, 140 mg/kg of Pb, 479 mg/kg of Cu, and 238 mg/kg 142 of Zn.
contained 5670 mg of Fe /kg of mine waste
contained 5670 mg Fe /kg mine waste
7.
4.Conclusions
291 In order to enhance the recovery of valuable metals from mine waste, various meth2
92 ods of bioleaching characterized by bio-adaptation and bio-oxidation were carried out us
293 ing a pyrrhotite sample obtained from an abandoned mine and indigenous bacteria (A.
294 ferrooxidans) inhabiting the acid mine drainage. The indigenous bacteria were cultured
295 and adapted for iron resistance. The pyrrhotite sample used here was prepared by crush
296 ing, grinding, sieving, and magnetic separation, and its pHpzc was estimated to be 3.0. Ac
297 cordingly, the initial pH of the bioleaching solution was controlled at 2.8 and 3.2 in view
298 of the surface charge of the pyrrhotite sample.
Most of the conclusions do not concern the results of Fe bioleaching from waste. Rather, it repeats the sentences from Chapter 2 (Materials and methods). Please briefly present the main results of the work, which are contained in subchapters 3 (Results and Discussion).
Author Response
Thanks for your comment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The article is useful for bioleaching of pyrrhotite.
Please check the following parts.
Line 30; Fe is usually main sources from oxide, not from sulfides.
Line77; 20 mesh is 833 micron in Tyler and 841 micron ASTM, not 1130nmicron.
Line 79; Unit should be unified. 2000 Gauss is 0.2T like in Figure 2.
Line 135; l of El is subscript.
In Figure 3, is it possible to write the error bars clearly?
In Figure 4, the color of graph is not clear. Please change the expression.
The characters in Figure is too small. Please write larger.
After the reaction has Jarosite not been observed?
Author Response
Thanks for your comment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Dear authors,
thanks for beginning to improve the paper. I have some more remarks to the attachment of bacteria to mineral. The figure 7 was added to prove the better attachment of bacteria at lower pH values. Both parts of figure 7 differ in magnitude and support material. Fig 7a looks like a section of mineral and fig 7b looks like membrane filter. None of the pictures show slime layer. With the Zetasizer Nano-ZS MPT-2 the zetapotential of cells could be measured and there were less speculation about the nature of interaction between mineral and bacteria.
Author Response
Thank you for the comment.
Author Response File: Author Response.pdf
Round 3
Reviewer 1 Report
I understood your explainations. But in generell it would be nice to see a proof of postualtes in results as well.
Author Response
Thank you very much for your interest and advice on our paper.
Author Response File: Author Response.pdf
