Selective Recovery of Tellurium from the Tellurium-Bearing Sodium Carbonate Slag by Sodium Sulfide Leaching Followed by Cyclone Electrowinning
Round 1
Reviewer 1 Report
Detailed eview will be sent as an attachment in a separate email
Comments for author File: 
Comments.pdf
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
The authors have carried out useful research into the production of elemental tellurium. However as with many authors presenting results in English which is not their first language, substantial changes would need to be made to the grammar and style before the paper could be published.
Tellurium is not a metal as stated on line 33. It is a metalloid, a calcogen part of Group 16.
Thermodynamically the reduction of tellurium dioxide by sulfur dioxide is very favorable at low temperatures. This does not appear to be consistent with the statement made on line 54. This reviewer wonders why the reduction reaction described on line 55 used hydrochloric acid when a cheaper and less corrosive sulfuric acid can be used.
On line 58, the authors claim that tellurium and its compounds have some toxicity. While many bacteria and fungi are affected by tellurium, tellurium and its compounds appear not to have any biological function and are simply accumulated. The maximum exposure for humans is 25 mg/cubic metre over 8 hours.
Figures 1a and 4 need to be larger to allow data to be extracted. The X-ray wavelength (or target and filters) need to be stated.
The particle size of the slag used in the leaching studies must be stated and the authors need to explain how they confirmed that all particles were fully suspended at a paddle speed of 300 rpm.
Tellurium is present in the solid slag as sodium tellurite and sodium tellurate. However, once taken into aqueous solution, the tellurium will be present as thiotellurite and thiotellurate ions not as sodium compounds. The data shown in Table 2 must reflect this. Similarly, all equations for chemical reactions occurring in the aqueous phase must be written to show the actual species involved.
What is the basis for deciding the "optimum conditions"? this needs to be stated.
Table 3 repeated. What is meant by "..valuable metals 832' on line 221? What is Cua in Table 4? Also on Table 5, what is "Nab"? It is certainly not "mg/L" since the data are "weight %".
The captions on Figures 3,5, 8 and 11 should give all the experimental conditions used.
The reference list is long. Are all essential? The names of bacteria (for example in reference 14) should be italicized.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Dear authors,
this paper provide new knowledge and comprehensive research on electrowinning. this paper can be published after following correction.
page7 line 221, metals 832 -> reference mistake?
Table 4. Cua ->Cu?
Figure 7. (b) 60A m2 -> 60A/m2
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The authors have made a very substantial improvement to their paper and are to be congratulated.
However, this reviewer is not convinced by the argument given as Response 6. In order to confirm that all particles are fully suspended during a leaching experiment is to conduct a series of experiments varying the agitator speed but keeping all other conditions the same. Once a particle is suspended in a fluid, its boundary layer thickness is fixed and essentially independent of agitator speed. One can be certain that all particles are fully suspended when leach rates are independent of agitator speed.
When interpreting X-ray diffraction data such as those shown as Figures 1 and 4, when the data has been generated using Cu Kα radiation (λ=1.5406 Å), one needs to remember that the incident radiation actually consists of two wavelengths (Cu Kα1 with λ=1.54056 and Cu Kα2 with λ=1.54439Å) and both will produce different diffraction peaks from the same d spacing. The doublets seen in diffraction patens may not be due to different compounds being present but to the two different wavelengths.
The authors should correct the minor grammatical and other errors listed below. Note that the list may not be complete.
- line 36. particularly the use...
- line 42. treatment processes..
- line 55. "However sulfur dioxide are environmentally unfriendly." Needs rewriting.
- line 60. leaching applied to tellurium..
- line 61. relative to present methods..
- line 95. .. eV corresponded..
- line 175. related compounds and ions..
- line 183. Table caption compounds and ions...
- line 183 within Table replace "compounds" by "species"
- line 344. electrolyte flow rate increased from 100 to 500 L/h.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
