Study on the Grinding Law of Ball Media for Cassiterite–Polymetallic Sulfide Ore
Round 1
Reviewer 1 Report
- It is recommended to check the results of the semi-quantitative analysis in lines 78-81. CaCO3 , why does it appear here?
- Lines 127-128: For most froth flotation of sulfides, particles of size in the appropriate range of 0.01 mm to 0.2 mm are ready to be floated. This sentence is not expressed clearly enough. Within these particle sizes (0.01-0.02mm, 0.02-0.038mm, 0.038-0.076mm, 0.076-0.12mm, and 0.12-0.2mm), there is a large difference in the flotation effect of the sulfide minerals. The poor recovery of these two particle sizes (the 0.01-0.02mm and 0.12-0.2mm) should be avoided. Therefore sulphide minerals should preferably not be over ground.
- Please try to explain the reason for the switch from 80% to 70% grinding concentration.
- Please try to explain the reason for the grinding time being set at 8 minutes.
- Please try to explain the reasons for having unpredictable results beyond the transition point （ 46.16m2/m3）.
Author Response
Respond to reviewer :
Question 1:
It is recommended to check the results of the semi-quantitative analysis in lines 78-81. CaCO3, why does it appear here?
Response 1:
Thank you very much for your suggestion. The results of chemical analysis show that the ore contains a certain amount of calcium carbonate. This is related to a certain amount of calcite in the mineral, which is consistent with the results of phase analysis.
Question 2:
Lines 127-128: For most froth flotation of sulfides, particles of size in the appropriate range of 0.01 mm to 0.2 mm are ready to be floated. This sentence is not expressed clearly enough. Within these particle sizes (0.01-0.02mm, 0.02-0.038mm, 0.038-0.076mm, 0.076-0.12mm, and 0.12-0.2mm), there is a large difference in the flotation effect of the sulfide minerals. The poor recovery of these two particle sizes (the 0.01-0.02mm and 0.12-0.2mm) should be avoided. Therefore sulphide minerals should preferably not be over ground.
Response 2:
Special thanks to you for your good comments. According to your suggestion, we have made a revision in the revised manuscript.
Question 3:
Please try to explain the reason for the switch from 80% to 70% grinding concentration.
Response 3:
Thank you very much for your suggestion. This is due to a writing error, for which we are very sorry. The grinding concentration set for all grinding tests in the manuscript is 70%.
Question 4:
Please try to explain the reason for the grinding time being set at 8 minutes.
Response 4:
Thank you very much for your suggestion. When studying the influence of grinding parameters on grinding particle size distribution, grinding time is an important influencing factor. If the grinding time is too short, the monomer dissociation of minerals cannot be realized, and the grinding time is too long, it is easy to lead to the occurrence of over grinding phenomenon. At the same time, it will also interfere with other influencing factors when studying them, and it is not sure which factors are working. Therefore, in this study, the grinding time is 8min, of course, 6min or 10min can also be selected.
Question 5:
Please try to explain the reasons for having unpredictable results beyond the transition point（46.16m2/m3）
Response 5:
Thank you very much for your suggestion. For the grinding medium (steel ball), the smaller the diameter of a single medium and the larger the total surface area of the grinding medium with the same total mass or volume, the grinding products with large fineness and narrow particle size distribution can be obtained in the grinding process. Therefore, when the total surface area exceeds a certain conversion point, there are unpredictable results for different particle sizes of grinding products.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The article is written on a rather current topic and is of academic interest. But there are a number of comments and questions about the article:
1. It does not say which ore (deposit) is the object of the study. This information would have provided a better understanding of the object of study.
2. In Figure 1, the axis is not signed exactly. Perhaps what is meant is: Passing, %
3. There is no information on how the chemical composition of the sample was determined.
4. The misprint on page 4, line 121 - 19 mm. Possibly meaning 0.019mm.
5. How was the content analysed in Table 1 (methods, equipment).
6. It is not clear why a grinding time of 8 minutes was chosen.
7. Figure 4 does not understand the caption of the abscissa axis.
8. Perhaps for a better understanding of the study, information on the analysis of intergrowths (liberation) at different grinding times should have been given.
Author Response
Respond to reviewer:
Question 1:
It does not say which ore (deposit) is the object of the study. This information would have provided a better understanding of the object of study.
Response 1:
Thank you very much for your suggestion. The object ore studied in this study is cassiterite polymetallic sulfide ore. The main valuable ore minerals are cassiterite, jamesonite, marmatite, pyrite, pyrrhotite and arsenopyrite. Gangue minerals include quartz, calcite, carbonaceous shale, etc.
Question 2:
In Figure 1, the axis is not signed exactly. Perhaps what is meant is: Passing, %
Response 2:
Thank you very much for your suggestion. According to your suggestion, we have made changes in the revised manuscript. It is “Cumulative yield under sieve/%”.
Question 3:
There is no information on how the chemical composition of the sample was determined.
Response 3:
Thank you very much for your suggestion. According to your suggestion, we have made changes in the revised manuscript. The elemental constituents of the test samples on basis of semi-quantitative analysis by X-ray fluorescence (XRF) analysis method are: SiO2 42%，CaCO3 22%，Fe2O3 12%，SO3 12%，Al2O3 5.8%，Zn 1.8%，K2O 1.1%，MgO 1.0%，Sn 0.6%，As 0.4%，Pb 0.3%，others 1%. Chemical analysis indicates the assaying of Sn in the test samples is 0.52%.
Question 4:
The misprint on page 4, line 121 - 19 mm. Possibly meaning 0.019mm.
Response 4:
Thank you very much for your suggestion. As you said, it is -0.019mm.
Question 5:
How was the content analysed in Table 1 (methods, equipment).
Response 5:
Thank you very much for your suggestion. In Section 2.2, we added specific equipment and grinding test operation methods. “Selective grinding refers to the non-equal crushing results of different mineral particles. Here, the selective grinding characterization method was analyzed with regard to the selective grinding behavior based on the changing cumulative grade and cumulative quantity of metal. A laboratory-scale conical type ball mill, with a cylinder of 240 mm in outer diameter by 90 mm in length, was employed to carry out grinding tests. The inner wall of the mill cylinder was smooth and the cylinder wall was 5mm in thickness. The mill had 6300 mL effective volume and was run at 85 rev/min equivalent to 96% of its critical rotary speed.
The specific operation method of grinding is as follows: according to the conditions of certain grinding concentration, add water to the mill first, then pour the ore sample to be grinded into the machine, cover the machine cover, start the mill and start timing; After grinding to the predetermined time, stop the machine and pour the product into the basin. Wash the slime adhered to the cylinder wall and steel ball surface into the basin with a small amount of water (usually washing bottle). Screen, dry and weigh the ground product and calculate the content of each particle size. ”
Question 6:
It is not clear why a grinding time of 8 minutes was chosen.
Response 6:
Thank you very much for your suggestion. When studying the influence of grinding parameters on grinding particle size distribution, grinding time is an important influencing factor. If the grinding time is too short, the monomer dissociation of minerals cannot be realized, and the grinding time is too long, it is easy to lead to the occurrence of over grinding phenomenon. At the same time, it will also interfere with other influencing factors when studying them, and it is not sure which factors are working. Therefore, in this study, the grinding time is 8min, of course, 6min or 10min can also be selected.
Question 7:
Figure 4 does not understand the caption of the abscissa axis.
Response 7:
Thank you very much for your suggestion. The meaning of Figure 4 shows the influence of different diameter ball ratio on the particle size distribution of grinding products. As shown in Figure 4 (a), the abscissa represents the proportion of 16mm ball when 40mm and 16mm ball are combined. When the abscissa is 0, it represents that the content of 16mm ball is 0.
Question 8:
Perhaps for a better understanding of the study, information on the analysis of intergrowths (liberation) at different grinding times should have been given.
Response 8:
Thank you very much for your suggestion. You have provided us with valuable ideas and methods. We will focus on the influence of grinding time on mineral dissociation in the next research with the help of MLA and SEM-EDS equipment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
- The paper on lines 78-81 shows "The elemental constituents of the test samples on basis of semi-quantitative analysis by X-ray fluorescence (XRF) analysis method are: SiO2 42%，CaCO3 22%，Fe2O3 12%，SO3 12%，Al2O3 5.8%，Zn 1.8%，K2O 81 1.1%，MgO 1.0%，Sn 0.6%，As 0.4%，Pb 0.3%，others 1%. " The CaCO3, Sn, Zn, As and Pb is the result from XRF? please check it again. The data maybe provided by XRF.
- Please explain the reason for the grinding time being set at 8 minutes based on Table 1. Table 1 gives two groups of data. However, 8 minutes is not an turning point. Why was it chosen? and What was the basis for its chosen?
- I understand the author's point.However, it is necessary for the author to explain. Is this unpredictability due to poor repeatability caused by the oversized specific surface area of the steel balls? Or is it for other reasons?
- It would be beneficial for the publication of this paper if the authors could clarify the issue of reproducibility of the tests in the paper.
Author Response
Respond to reviewer #1:
Question 1:
The paper on lines 78-81 shows "The elemental constituents of the test samples on basis of semi-quantitative analysis by X-ray fluorescence (XRF) analysis method are: SiO2 42%，CaCO3 22%，Fe2O3 12%，SO3 12%，Al2O3 5.8%，Zn 1.8%，K2O 81 1.1%，MgO 1.0%，Sn 0.6%，As 0.4%，Pb 0.3%，others 1%. " The CaCO3, Sn, Zn, As and Pb is the result from XRF? please check it again. The data maybe provided by XRF.
Response 1:
Thank you very much for your suggestion. These data are obtained from the detection of XRF equipment.
Question 2:
Please explain the reason for the grinding time being set at 8 minutes based on Table 1. Table 1 gives two groups of data. However, 8 minutes is not an turning point. Why was it chosen? and What was the basis for its chosen?
Response 2:
Special thanks to you for your good comments. It can be seen from table 1 that with the increase of grinding time, -0.038mm particle size content gradually increases, indicating that the extension of grinding time helps to increase grinding fineness. In terms of grinding rate, the grinding rate increases gradually when the grinding time increases from 4min to 8min, and decreases gradually as the grinding time continues to extend from 8min. This is because the finer the particle size, the harder it is to grind. Therefore, the grinding time here is selected as 8min.
Question 3:
I understand the author's point. However, it is necessary for the author to explain. Is this unpredictability due to poor repeatability caused by the oversized specific surface area of the steel balls? Or is it for other reasons ?
Response 3:
Thank you very much for your suggestion. During the operation of the ball mill, the factors affecting the grinding effect include grinding time, filling rate, grinding concentration, etc. within a certain range, increasing the grinding time or increasing the filling rate will improve the grinding effect and reduce the grinding particle size. However, with the continuous extension of grinding time or the continuous increase of filling rate, the particle size reduction rate of grinding products decreases gradually. With the increase of the surface area of the medium (steel ball) of the ball mill, the filling rate also increases gradually, and the grinding effect also shows a strong trend first and then weak trend.
Question 4:
It would be beneficial for the publication of this paper if the authors could clarify the issue of reproducibility of the tests in the paper.
Response 4:
Thank you very much for your suggestion. We have explained in the third question, which mainly involves the influence law of filling rate on grinding effect. As the answer to the third question, if the filling rate is too large, it will have an adverse impact on the grinding effect.
Author Response File: Author Response.pdf
Reviewer 2 Report
The authors responded to all questions and comments. The article can be published.
Author Response
Thank you very much
Round 3
Reviewer 1 Report
- The author explained all my doubts. However, the author did not add them into the paper. I think that the answers to these queries should be added to the paper in the appropriate place. This would be helpful for the reader to understand the paper.
- I was under the impression that the XRF results should be for oxide content, not elemental content. I suggest the authors check again.
Author Response
Respond to reviewer #1:
On behalf of my co-authors, we thank you very much for giving us an opportunity to revise our manuscript ID minerals-1572466 entitled "Study on Grinding Law of Ball Medium about Cassiterite-polymetallic Sulfide Ore". We are thankful to you for pointing out some important modifications needed in the report. We have thoughtfully taken into account these comments. The main corrections and explanation of what we have changed in response to the comments is given point by point in the following pages, and the modified part has been marked red in the revised manuscript.
Question 1:
The author explained all my doubts. However, the author did not add them into the paper. I think that the answers to these queries should be added to the paper in the appropriate place. This would be helpful for the reader to understand the paper.
Response 1:
Thank you very much for your suggestion. We have added corresponding explanations in the appropriate position in the revised manuscript. For example, on lines 169 to 175: “Meanwhile, it can be seen from Table 1 that with the increase of grinding time, -0.038 mm particle size content gradually increases, indicating that the extension of grinding time helps to increase grinding fineness. In terms of grinding rate, the grinding rate increases gradually when the grinding time increases from 4min to 8 min, and decreases gradually as the grinding time continues to extend from 8 min. This is because the finer the particle size, the harder it is to grind. Therefore, the grinding time here is selected as 8 min.” on lines 349 to 354: “Within a certain range, increasing the filling ratio will improve the grinding effect and reduce the grinding particle size. However, with the continuous increase of filling ratio, the particle size reduction rate of grinding products decreases gradually. With the increase of the surface area of the medium (steel ball) of the ball mill, the filling ratio also increases gradually, and the grinding effect also shows a strong trend first and then weak trend. This is consistent with the conclusions obtained in Figures 2 and 3.”
Question 2:
I was under the impression that the XRF results should be for oxide content, not elemental content. I suggest the authors check again.
Response 2:
Special thanks to you for your good comments. We have carefully verified that, as you suggested, the XRF result is in the form of oxide, and we have made changes in the revised manuscript, as follows: “ZnO 2.2%，SnO2 0.8%，As2O3 0.5%，PbO 0.3%，others 0.3%. ”
Author Response File: Author Response.pdf
