Risk Assessment of Potentially Toxic Elements Pollution from Mineral Processing Steps at Xikuangshan Antimony Plant, Hunan, China
Round 1
Reviewer 1 Report
Manuscript ID - processes-652220
Pollution Characteristics of Potentially Toxic Elements (PTEs) in Xikuangshan Antimony Mineral Processing Plant of Hunan, China
General Comments for Authors
The main aim of the paper was to characterize the potentially toxic elements (PTEs) in a typical processing enterprise in XKS Antimony Mine in Hunan Province in China. The wastewater, dust and solid waste from the mine have been analysed to potentially toxic elements (Sb, As, Hg, Pb, Cd and Zn) in order to understand the sources of pollution, the degree of pollution and hazards of PTEs in the whole process of antimony beneficiation. Also the obtained results should provide reference for the prevention and control of PTEs pollution in antimony mineral processing.
The paper deals with very important environmental issue, but there are some parts in the manuscript which are poor and not clear. So in order to improve this manuscript and to raise its impact, the Authors should pay attention to following:
- Introduction should be expanded by negative impacts of investigated heavy metals on the soil, surface and groundwater as well as on humans
- In Materials and Methods section Authors should give more information about Antimony Mine. Also what about the surface waters or groundwater in the mine surrounding, or agriculture?
- In Results and Discussion section there is a lack of discussion, for example about the obtained results, the reasons for so high concentrations of PTEs, possible solutions, etc. It is not enough only to present the obtained results.
- In conclusions Authors only listed the main findings without giving the possible solutions or suggestions for controlling or preventing the pollution during antimony mineral processing, and which are mentioned as one of the aims of this study.
Detail comments
Abstract
The first sentence in lines 12-17 is too long and it should be splitted.
After reading the whole abstract, the wrong impression is left in view of PTEs. It seems that the Authors investigated first the concentrations of Sb, As and Zn (line 17), then the concentrations of some other PTEs (line 18), and later again appear more of metals - Cd, Pb, Hg (line 23). To avoid confusion the best solution is to highlight in line 14 exactly which are the PTEs analysed in this study.
Line 14 - Although the full name for PTEs is mentioned in the title, it should be also given in the abstract. Afterwards only the abbreviation can be used.
Line 17 - The full name for mentioned elements should be given here, or in line 14, with the abbreviation in the brackets. In that way the abbreviations can be used further in the text.
Introduction
The negative impacts of investigated heavy metals on the environment as well as humans should be added in the introduction section.
Material and Methods
There is a lack of data about XKS Antimony Mine. For example for how long this mine is active, how much antimony has been produced in that time, what is the total quantity of produced waste, what they are doing with that waste, where they are taken care of wastewater and tailings, etc.? What about the surface waters or groundwater in the mine surrounding, or agriculture?
Line 69 - Missing space between the number and units.
Line 81 - A small straight line (-) should be used here to indicate the range from - to
Line 86-87: The sentence - Each final sample was made of 3 parallel samples at the sampling points that were evenly mixed; What samples does this sentence refer to? Only on surface soil samples or all? It is not clear.
Line 93 and line 95 - Missing space between the number and units.
Line 101 - Be careful with the beginning of the sentence.
Line 116 - In which samples, wastewater, dust and tailings? This should be added in this section.
What exactly represents the environmental background value (Cb)? Is it according to legislations and maximum permissible concentrations, or Authors analysed these values by themselves? If yes, in which samples (from where these samples were sampled)?
Or it is according to the available data in literature? If so, this should be mentioned here. It is not clear in this way.
Line 128: Again, in which samples – in wastewater, dust and tailings?
Results and Discussions
There is a lack of discussion about the obtained results in this section, the reasons for so high concentrations of PTEs, possible solutions, etc.
Line 141 - Pay attention to the units, mg/L or mgL-1, not both.
Why the sentence The concentration of PTEs in wastewater from antimony beneficiation process is shown in Table 1 (lines 143 - 144) is not before the Table 1? It seems more appropriate.
The first column in Table 1 should be rearranged.
Lines 146-147 - Check for the sentence The average concentrations of Sb, As and Pb in wastewater are 4.415 mg·L-1 , 1.006 tank mg·L-1 and 1.536 mg·L-1 , respectively.
Line 148 - the sampling sites W5, W4 and W6 should be listed in order W4, W5 and W6.
Lines 170, 172 and 180 - waste water should be equalized as elsewhere in the text as wastewater.
Table 5 - the columns for PI(Sb), Er(Sb) and Er(Cd) as well as for RI must be wider so the number can be in one line.
Line 238 - As can be seen from Table 5, PI of Sb has a maximum value of 555.18, higher than the standard,… which standard is this?
Lines 246-247 - Authors should check for this sentence and rearrange it. How come that Figures 5 and 6 have the completely same title? It cannot be. Is the proportion of each PTE in different types of samples (wastewater, dust, tailings) presented in Figure 5? If yes, then the sentence in line 246-247 should be rearranged as well as title of Fig. 5, in accordance to that.
Does Fig. 6 represent the percentage of total PTEs in different types of samples? If yes, then the sentence in line 252 as well as title of Fig. 6 must be changed according to this.
The resolution of Fig. 6 is very poor, this should be corrected.
Conclusion
In this section Authors only listed the main findings, but conclusion should not be just listing the results obtained. What are missing are possible reasons for so high pollution as well as the suggestion for preventing the pollution or at least to have the pollution under control.
It is obvious that pollution is present but how can further pollution be prevented and what steps can be taken now to prevent further negative environmental impacts? How wastewater should be treated? In which ways the remediation of the contaminated environment in the area around the mine can be performed?
Because the aim of this study is not only to determine if there is pollution, but also how to control and prevent the pollution during antimony mineral processing.
In accordance to this the Results and Discussion section as well as Conclusion section should be expanded.
Author Response
Detail comments
Abstract
The first sentence in lines 12-17 is too long and it should be splitted.
Revised
After reading the whole abstract, the wrong impression is left in view of PTEs. It seems that the Authors investigated first the concentrations of Sb, As and Zn (line 17), then the concentrations of some other PTEs (line 18), and later again appear more of metals - Cd, Pb, Hg (line 23). To avoid confusion the best solution is to highlight in line 14 exactly which are the PTEs analysed in this study.
Revised
Line 14 - Although the full name for PTEs is mentioned in the title, it should be also given in the abstract. Afterwards only the abbreviation can be used.
Revised
Line 17 - The full name for mentioned elements should be given here, or in line 14, with the abbreviation in the brackets. In that way the abbreviations can be used further in the text.
Revised
Introduction
The negative impacts of investigated heavy metals on the environment as well as humans should be added in the introduction section.
Revised
Material and Methods
There is a lack of data about XKS Antimony Mine. For example for how long this mine is active, how much antimony has been produced in that time, what is the total quantity of produced waste, what they are doing with that waste, where they are taken care of wastewater and tailings, etc.? What about the surface waters or groundwater in the mine surrounding, or agriculture?
Revised
Line 69 - Missing space between the number and units.
Revised
Line 81 - A small straight line (-) should be used here to indicate the range from - to
Revised
Line 86-87: The sentence - Each final sample was made of 3 parallel samples at the sampling points that were evenly mixed; What samples does this sentence refer to? Only on surface soil samples or all? It is not clear.
Revised
Line 93 and line 95 - Missing space between the number and units.
Revised
Line 101 - Be careful with the beginning of the sentence.
Revised
Line 116 - In which samples, wastewater, dust and tailings? This should be added in this section.
What exactly represents the environmental background value (Cb)? Is it according to legislations and maximum permissible concentrations, or Authors analysed these values by themselves? If yes, in which samples (from where these samples were sampled)?
Or it is according to the available data in literature? If so, this should be mentioned here. It is not clear in this way.
Revised
Line 128: Again, in which samples – in wastewater, dust and tailings?
Revised
Results and Discussions
There is a lack of discussion about the obtained results in this section, the reasons for so high concentrations of PTEs, possible solutions, etc.
Line 141 - Pay attention to the units, mg/L or mgL-1, not both.
Revised
Why the sentence The concentration of PTEs in wastewater from antimony beneficiation process is shown in Table 1 (lines 143 - 144) is not before the Table 1? It seems more appropriate.
Revised
The first column in Table 1 should be rearranged. Revised
Lines 146-147 - Check for the sentence The average concentrations of Sb, As and Pb in wastewater are 4.415 mg·L-1 , 1.006 tank mg·L-1 and 1.536 mg·L-1 , respectively.
Revised
Line 148 - the sampling sites W5, W4 and W6 should be listed in order W4, W5 and W6.
Revised
Lines 170, 172 and 180 - waste water should be equalized as elsewhere in the text as wastewater.
Revised
Table 5 - the columns for PI(Sb), Er(Sb) and Er(Cd) as well as for RI must be wider so the number can be in one line.
Line 238 - As can be seen from Table 5, PI of Sb has a maximum value of 555.18, higher than the standard,… which standard is this?
revised
Lines 246-247 - Authors should check for this sentence and rearrange it. How come that Figures 5 and 6 have the completely same title? It cannot be. Is the proportion of each PTE in different types of samples (wastewater, dust, tailings) presented in Figure 5? If yes, then the sentence in line 246-247 should be rearranged as well as title of Fig. 5, in accordance to that.
revised
Does Fig. 6 represent the percentage of total PTEs in different types of samples? If yes, then the sentence in line 252 as well as title of Fig. 6 must be changed according to this.
revised
The resolution of Fig. 6 is very poor, this should be corrected.
revised
Conclusion
In this section Authors only listed the main findings, but conclusion should not be just listing the results obtained. What are missing are possible reasons for so high pollution as well as the suggestion for preventing the pollution or at least to have the pollution under control.
It is obvious that pollution is present but how can further pollution be prevented and what steps can be taken now to prevent further negative environmental impacts? How wastewater should be treated? In which ways the remediation of the contaminated environment in the area around the mine can be performed?
Because the aim of this study is not only to determine if there is pollution, but also how to control and prevent the pollution during antimony mineral processing.
In accordance to this the Results and Discussion section as well as Conclusion section should be expanded.
Revised
Author Response File: 
Author Response.docx
Reviewer 2 Report
Line 14 and line 39. Please, write full abbreviate of PTE - Potentially Toxic Elements (PTE).
Line 43. Write the coordination of Xikuangshan (XKS) Antimony Mine in Lengshuijiang in XX.XXXXXX XX.XXXXXXX style.
Line 60-64. It is necessary to write full chemical formulas of minerals, like stibnite (Sb2S3) and etc.
Table 1. What's the pH of water samples?
Table 2, 3, 4. Do you analyze the XRD of solid samples? Maybe these samples have a different mineral composition that accumulates Sb, As, Zn and etc. on their surface or structure? Did you study the distribution of impurities in the structure of solid samples using SEM-EDX method?
Figure 5. Add colours to this figure.
Figure 6. This chart has poor quality.
Chapter 3.4. From your research, it follows that the content of metals (Sb, As, Zn) significantly exceed the permissible norms and background value for the Hunan Province. With prolonged contact this impurity (water, dust and solid samples) with factory workers, how can it influence on their health? Is it possible for the emergence of chronic diseases? What're the methods do you propose to neutralize the negative impact?
Author Response
Comments and Suggestions for Authors
Line 14 and line 39. Please, write full abbreviate of PTE - Potentially Toxic Elements (PTE).
revised
Line 43. Write the coordination of Xikuangshan (XKS) Antimony Mine in Lengshuijiang in XX.XXXXXX XX.XXXXXXX style.
revised
Line 60-64. It is necessary to write full chemical formulas of minerals, like stibnite (Sb2S3) and etc.
revised
Table 1. What's the pH of water samples?
Antimony ore flotation needs to adjust the pH, so the sampling did not determine the pH value
Table 2, 3, 4. Do you analyze the XRD of solid samples? Maybe these samples have a different mineral composition that accumulates Sb, As, Zn and etc. on their surface or structure? Did you study the distribution of impurities in the structure of solid samples using SEM-EDX method?
I analyzed the XRD and SEM of solid sample (See “The Impact of Physical Properties on the Leaching of Potentially Toxic Elements from Antimony Ore Processing Wastes”. International Journal of Environmental Research and Public Health, doi:10.3390/ijerph16132355)
Figure 5. Add colours to this figure.
Revised
Figure 6. This chart has poor quality.
Revised
Chapter 3.4. From your research, it follows that the content of metals (Sb, As, Zn) significantly exceed the permissible norms and background value for the Hunan Province. With prolonged contact this impurity (water, dust and solid samples) with factory workers, how can it influence on their health? Is it possible for the emergence of chronic diseases? What're the methods do you propose to neutralize the negative impact?
Revised
Author Response File: 
Author Response.pdf
Round 2
Reviewer 1 Report
Manuscript ID - processes-652220
Risk Assessment of Potentially Toxic Elements (PTEs) Pollution from Mineral Processing Steps at the Xikuangshan Antimony Plant, Hunan, China
Comments for Authors
The manuscript is greatly improved. Still, the spell check is required, and some errors in the text should be corrected, so please pay attention to the following:
- In the introduction section there is a difference in font size as well as in line spacing so Authors should correct this
- Line 157: Authors added three references, one of them is Chinese Environmental quality standards for surface water and other two are manuscripts. One of them deals with As and Sb in water and wastewater and other with background values of soil. After addition of these references, still it is not clear what exactly represents value of Cb, since I didn't get the answer. The question was:
What exactly represents the environmental background value (Cb)? Is it according to legislations and maximum permissible concentrations, or Authors analysed these values by themselves? If yes, in which samples (from where these samples were sampled)? Or it is according to the available data in literature? If so, this should be mentioned here. It is not clear in this way.
- Lines 304-309: Check for the font size in this paragraph
- Figs. 5 and 6: These figures are still hardly visible.
Author Response
Modifications have been made according to the comments of reviewer
Author Response File: Author Response.pdf
