Effect of Mg Concentration on the Aluminothermic Reduction of Mn2O3 Particles Obtained from Cathodes of Discharged Alkaline Batteries: Mathematical Modeling and Experimental Results
Round 1
Reviewer 1 Report
In their contribution “Effect of Mg Concentration on the Aluminothermic Reduction of Mn2O3 Particles Obtained from Cathodes of Discharged Alkaline Batteries: Mathematical Modeling and Experimental Results”, Flores et al. report on the reaction of aluminum and magnesium with Mn2O3, which is obtained from the cathodes of discharged alkaline batteries. In addition, the authors provide a plausible reaction mechanism including the respective reaction kinetics. Although this interesting contribution is suited for publication in metals, yet, there are certain issues that need to be revised prior to a publication of the manuscript.
The representation of the induction furnace is quite sparse. To improve the quality of that figure, it will be helpful to provide more technical details and an inset showing the actual furnace.
It is not clear how the compositions of the respective samples have been determined. Did the authors collect sets of powder X-ray diffraction patterns and conduct Rietveld refinements based on the diverse X-ray diffraction patterns? Did the authors determine the compositions based on EDX spectra? Did the authors monitor the reactions by using scanning electron microscopy? Therefore, the authors should provide more details regarding the experimental results and techniques.
In figure 2, powder X-ray diffraction patterns of the diverse samples have been presented; however, the authors did not provide any information regarding the powder X-ray diffraction experiments - please add this very relevant information.
It is mentioned that the Gibbs free energy was computed using the HSC 6.12 software; yet, the authors do not provide any information regarding the computational details – please provide this information.
In figure 8, there is a nice representation of the reaction mechanism – did the authors also make use of scanning electron microscopy in order to verify the distributions of the respective components?
Author Response
Point 1: In their contribution “Effect of Mg Concentration on the Aluminothermic Reduction of Mn2O3 Particles Obtained from Cathodes of Discharged Alkaline Batteries: Mathematical Modeling and Experimental Results”, Flores et al. report on the reaction of aluminum and magnesium with Mn2O3, which is obtained from the cathodes of discharged alkaline batteries. In addition, the authors provide a plausible reaction mechanism including the respective reaction kinetics. Although this interesting contribution is suited for publication in metals, yet, there are certain issues that need to be revised prior to a publication of the manuscript.
Response 1: Thanks for your comments on the manuscript.
Point 2: The representation of the induction furnace is quite sparse. To improve the quality of that figure, it will be helpful to provide more technical details and an inset showing the actual furnace.
Response 2: Figure 1 was changed to a representative photo of the induction furnace.
Point 3: It is not clear how the compositions of the respective samples have been determined. Did the authors collect sets of powder X-ray diffraction patterns and conduct Rietveld refinements based on the diverse X-ray diffraction patterns? Did the authors determine the compositions based on EDX spectra? Did the authors monitor the reactions by using scanning electron microscopy? Therefore, the authors should provide more details regarding the experimental results and techniques.´
Response 3: In lines 108 and 109 the specifications of the equipment used for the chemical analysis of the metallic samples are not given, the brand of the equipment used was added. The analyses performed were only for metallic sample obtained every 15 minutes during all the process of thermic reduction in order to determine the incorporation of metallic manganese into liquid aluminium.
For x-ray diffraction analysis, Rietveld refinement was not used, X-ray diffraction analyses were only carried out to identify the compounds present in the reaction products of the thermic reduction at the end of the process, so it was not carried out the quantification of compounds.
The reactions were not analyzed by SEM, as the Aluminothermic reduction process went to 1073K
Point 4: In figure 2, powder X-ray diffraction patterns of the diverse samples have been presented; however, the authors did not provide any information regarding the powder X-ray diffraction experiments - please add this very relevant information.
Response 4: Slag samples, were taken at the end of each one of the experiments performed, letting to cool-down to room temperature thereafter, an amount of 150 g mas milled in a mortar, sieved to – 200 mash. Then the powder obtainer was analyzed by the X ray diffraction technique using an X Philips equipment using Cu-Kα radiation.
Point 5: It is mentioned that the Gibbs free energy was computed using the HSC 6.12 software; yet, the authors do not provide any information regarding the computational details – please provide this information.
Response 5: In the HSC software there are several toolbars between it is a call (Reaction equations), which provides theoretical data from the Gibbs free energies to the temperature of interest. This software has a database of CP, ΔH and ΔS at different temperatures, the limes facilitate thermodynamic calculations and eliminate mathematical errors.
Point 6: In figure 8, there is a nice representation of the reaction mechanism – did the authors also make use of scanning electron microscopy in order to verify the distributions of the respective components?
Response 6: We have added figure 9, which is a X- ray map by EDS in the SEM of a Mn particle extracted from the bath at 1073 k, after 240 minutes of reaction, for in initial Mg concentration of 4 wt. % around this particle it is clearly shown the reaction products surrounding it we have improved the text giving a broad discussion.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The aim of the work, stated by the authors is very topical, so recycling is very important to improve the ecological situation.
The presented results both in the experimental part and in modeling do not stand up to scrutiny.
The paper did not carry out a full-fledged analysis of the products obtained (alloys), only the results of X-ray phase analysis are presented, and even the results of electron microscopy and chemical analysis are not given.
Graphic dependencies are presented without confidence intervals.
Formulas 13, 15 and 17, as well as 14, 16 and 18 could be represented by two formulas with variable indices.
The model laid down by the authors in a numerical account looks overly simplified, large assumptions are made.
The process of aluminothermic reduction of manganese oxides in the presence of another reducing agent proceeds according to a more complex mechanism. In the course of recovery, competing processes and a merger stage arise.
The conclusions require significant refinement.
Author Response
Point 1: The aim of the work, stated by the authors is very topical, so recycling is very important to improve the ecological situation.
Response 1: Thank you for the comments and suggestions of the manuscript.
Point 2: The presented results both in the experimental part and in modeling do not stand up to scrutiny
Response 2: The changes in the section of experimental results and mathematical models in order to be clearer, taking into account their comments.
Point 3: The paper did not carry out a full-fledged analysis of the products obtained (alloys), only the results of X-ray phase analysis are presented, and even the results of electron microscopy and chemical analysis are not given.
Response 3: According to your comment we have added Figure 9, which is an X-ray map by EDS in the SEM of a manganese particle, to the condoms of 1073K and with an initial concentration of magnesium of 4 wt. %, where one can observe a manganese particle surrounded by the reaction products raised spinel.
Point 4: Graphic dependencies are presented without confidence intervals.
Response 4: Figures 3 and 4 were modified and the confidence intervals were inserted.
Point 5: Formulas 13, 15 and 17, as well as 14, 16 and 18 could be represented by two formulas with variable indices.
Response 5: The formulas 13, 14 and 15 were grouped into equation 13 and on the other hand the formula 14 15 and 16 were grouped into equation 14.
Point 6: The model laid down by the authors in a numerical account looks overly simplified, large assumptions are made.
Response 6: The steps to obtain the mathematical model that best adjusted the thermic derided reduction process in the line (210-214) were re-written in detail, the text.
Point 7: The process of aluminothermic reduction of manganese oxides in the presence of another reducing agent proceeds according to a more complex mechanism. In the course of recovery, competing processes and a merger stage arise.
Response 7: According to the Ellinghan diagram for the stability of oxides, Al and Mg would react whit Mn2O3 particle to deoxidize them, obtaining as a reaction product the spinel (MgAl2O4) Mg is dissolved in the molten bath, so it is the required condition to react whit the Mn2O3 particle this is a thermally activated processes so better condition which improves so agitation temperature etc. can improve wettability than the between reactants, improving kinetics of the process however, it is worth mentioning that the sequence of reaction of Mn2O3 is to go through a series of states of lower oxidation where the first step is the formation of Mn3O4 following deoxidations to MnO and finally to Mn the Mn released passed to the molten solution.
Point 8: The conclusions require significant refinement.
Response 8: Thank you for your suggestion was taken into account by the authors.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
In the revised version of the contribution "Effect of Mg Concentration on the Aluminothermic Reduction of Mn2O3 Particles Obtained from Cathodes of Discharged Alkaline Batteries: Mathematical Modeling and Experimental Results", Flores et al. have adequately addressed most of the reviewer´s concerns
There is just one minor point remaining: please add a brief paragraph, which describes the collections of the PXRD patterns, the SEM images, and the EDS maps and also includes the technical details of the used instrumentation (as e.g. the type of the used diffractometer), to the 'Materials and Methods' section.
Author Response
Thank you for the review and comments of the manuscript
Author Response File: Author Response.pdf
Reviewer 2 Report
Good Luck!
Author Response
Response to Reviewer 2 Comments
Point 1 Comments and Suggestions for AuthorsGood Luck!Response 1: Thank you for the review and comments of the manuscript
