Effect of Sulfur Content on Copper Recovery in the Reduction Smelting Process
Round 1
Reviewer 1 Report
Dear Authors,
Congratulations on the issue taken and on the interesting research methodology. The use of thermodynamic modeling and the verification of its results through an experiment is the correct research methodology. However, corrections are needed to improve the manuscript.
Recomendations and comments;
1. it is worth supplementing the "introduction" by developing the issues mentioned in the cited research
2, since Table 1 contains data obtained from the literature, it should be clearly stated whether the authors recreated the analyzes carried out by other researchers, or whether they were only inspiration
3.line 131, give definitions of all notations used in the equation
4. lines from 121 to 131, you should format correctly of the text- according to the editor's instructions
5. I suggest you change the titles: Fig.3. Phase diagram ....., either discard the parentheses or write the text between the brackets with a lowercase letter - excluding the program name. Similar comments to Figures 4 and 5.
6. check the chart editing rules and standardize the font size; consider saving the model curve formulas outside the plot area, e.g. next to the plots, to make them more pronounced
7. figures 5 and 9 are not marked with the letters (a) and (b) used in the titles
9. the uniform form of presentation and position of the statements in the manuscript should be kept (correction Fig. 9)
10. line 227: how is the indicated linkage expressed? - complete the information
11. line 234; change from Recovery to recovery
12. Do the authors have recommendations for the slag reduction process? they should be included in "conclusion"
Kind Regards,
Reviewer
Author Response
Thanks for your review. I revised the manuscript according to your suggestions and requirements
Recomendations and comments;
1. it is worth supplementing the "introduction" by developing the issues mentioned in the cited research
Response: Thanks for your suggestions. I have made a general description of many studies. I supplemented the introduction. I think the uncontrollable volatilization of Sulfur in the reduction process affected the instability of the actual recovery process to a large extent.
2, since Table 1 contains data obtained from the literature, it should be clearly stated whether the authors recreated the analyzes carried out by other researchers, or whether they were only inspiration
Response: Table 1 was to prove that my idea was founded. I have added some explanations about table 1 later. Table 1 is just a reference and summary
3.line 131, give definitions of all notations used in the equation
Response: Modified.
4.lines from 121 to 131, you should format correctly of the text- according to the editor's instructions
Response: Modified.
5.I suggest you change the titles: Fig.3. Phase diagram ....., either discard the parentheses or write the text between the brackets with a lowercase letter - excluding the program name. Similar comments to Figures 4 and 5.
Response: Modified.
6.check the chart editing rules and standardize the font size; consider saving the model curve formulas outside the plot area, e.g. next to the plots, to make them more pronounced
Response: Modified.
7.figures 5 and 9 are not marked with the letters (a) and (b) used in the titles
Response: Modified.
8.the uniform form of presentation and position of the statements in the manuscript should be kept (correction Fig. 9)
Response: Modified.
9.line 227: how is the indicated linkage expressed? - complete the information
Response: Revised. There was an ambiguous linkage.
10.line 234; change from Recovery to recovery
Response: Modified.
11.Do the authors have recommendations for the slag reduction process? they should be included in "conclusion"
Response: Dear reviewer. Low sulfur content requires the addition of oxidizing gas to the slag in the early stage. Cu loss in slag can be divided into sulfide dissolution and oxide dissolution. This process is in great contradiction with the current method. I don't want to give a specific process in this article. This may be controversial
Reviewer 2 Report
Effect of sulfur content on copper recovery in the reduction smelting process is very interesting paper. Some improvement is required.
Line 11: The effect of sulfur content on copper recovery under different oxygen partial pressures ( in temperature range between ...) was pointed
Line 13: the Recovery of copper and the stability of the experiment have an ideal results (95 % reduction efficiency?)
Line 65: Figure 1. Schematic diagram of separation of slag–matte (""left") and slag–metal systems ("right").
Line 74: Under the initial reduction condition, the variation range of sulfur content is 0 ~ 3% (Is this value stoichiometric required quantity for copper reduction?)
Line 105: The experiment was carried out in a high-temperature tubular furnace (Producer, Country)
Line 156, 157: However, under the condition of higher oxygen partial pressure, the reduction is inhibited by low sulfur, which is related to the phase the product. Please to write an equation for reduction and show what is the final product (Copper?)
Line 177: sulfur content has an inhibitory effect on the metal mass (which type of metal: copper? iron?)
Line 188:With the increase of sulfur content, a large amount of Cu remains in the slag. In which form is sulfur after reduction process (sulfur-oxide? Copper sulfide? iron sulfide?)
Line 199: the copper content less than 30 (Please to add "%")
Line 218: 0.2 can LCu accord with the thermodynamic law of reduction experiment. (what is the meaning of Lcu)
Line 226: , it can promote the Recovery of copper when a large amount of reducing agent (what is limit for an addition) is added
Line 237: At the same time, under the condition of high sulfur content (please to add a value of high sulfur content),
Line 240: The actual recovery experiment is not completely consistent with
the law of thermodynamics. (why? what is reason for this difference? How to improve it?)
Author Response
Thanks for your review. I revised the manuscript according to your comments.
Line 11: The effect of sulfur content on copper recovery under different oxygen partial pressures ( in temperature range between ...) was pointed
Response: revised
Line 13: the Recovery of copper and the stability of the experiment have an ideal results (95 % reduction efficiency?)
Response: Please allow me to explain. The recovery rate is closely related to the C / O mixed in the experiment. Under the conditions of this paper, I only express that it has an ideal result under the condition of low sulfur content and fixed C / O. Of course, with the increase of reducing agent, the yield will be further improved. This is the focus of this paper.
Line 65: Figure 1. Schematic diagram of separation of slag–matte (""left") and slag–metal systems ("right").
Response: revised
Line 74: Under the initial reduction condition, the variation range of sulfur content is 0 ~ 3% (Is this value stoichiometric required quantity for copper reduction?)
Response: revised. There is an error description
Line 105: The experiment was carried out in a high-temperature tubular furnace (Producer, Country)
Response: revised.
Line 156, 157: However, under the condition of higher oxygen partial pressure, the reduction is inhibited by low sulfur, which is related to the phase the product. Please to write an equation for reduction and show what is the final product (Copper?)
Response: revised. I added a more detailed explanation. Thanks for your reminder
Line 177: sulfur content has an inhibitory effect on the metal mass (which type of metal: copper? iron?)
Response: revised. This refers to the total mass of the metals received. Metals include metal and matte. Specific elements include Cu, Fe and S.
Line 188: With the increase of sulfur content, a large amount of Cu remains in the slag. In which form is sulfur after reduction process (sulfur-oxide? Copper sulfide? iron sulfide?)
Response: The reduced copper iron sulfide is the main form of sulfur, which also includes the dissolved sulfur in some slag. The main reason for copper remaining in the slag is not because no metal or matte formed. However, in the limited holding time, the metal cannot gather at the bottom through settlement to realize the separation of slag and metal.
Line 199: the copper content less than 30 (Please to add "%")
Response: modified
Line 218: 0.2 can LCu accord with the thermodynamic law of reduction experiment. (what is the meaning of Lcu)
Response: Formula 2 defined Lcu.
Line 226: , it can promote the Recovery of copper when a large amount of reducing agent (what is limit for an addition) is added.
Response: modified
Line 237: At the same time, under the condition of high sulfur content (please to add a value of high sulfur content),
Response: high sulfur content. High sulfur content is not a specific value. Referring to Fig. 3, for different oxygen partial pressure systems, the sulfur content required to generate matte is not consistent.
Line 240: The actual recovery experiment is not completely consistent with
the law of thermodynamics. (why? what is reason for this difference? How to improve it?
Response: I have explained it many times in the manuscript. When the reducing agent is added into the copper slag, the amount of metal produced was consistent with thermodynamics. However, because I can't collect the obtained metal in a limited time, the value obtained in the experiment must be contrary to thermodynamics. With the increase of holding time, the experimental results will gradually be close to the thermodynamic results, but this is impossible in the actual production process. Factors limiting metal yield include thermodynamic equilibrium and metal separation. With the increase of sulfur content, the metal phase is matte, which is more difficult to settle at the bottom due to the difference of density. In essence, it is not conducive to metal recovery in a limited time.
