Direct-on-Filter FTIR Spectroscopy to Estimate Calcite as A Proxy for Limestone ‘Rock Dust’ in Respirable Coal Mine Dust Samples
Round 1
Reviewer 1 Report
The paper proposes to adopt FTIR spectroscopy to estimate the presence of calcite in respirable coal mine dust samples. The authors have addressed the application and plausible sources of error very well. Authors have reported particle loading and extremely low masses in certain cases. This is a novel approach, and the study was done systematically. The manuscript should be accepted for publication.
Author Response
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Reviewer 2 Report
The manuscript titled “Direct-on-filter FTIR Spectroscopy to estimate calcite as a proxy 2 for limestone ‘rock dust’ in respirable coal mine dust samples” is a paper that may be of interest to the readers of Minerals. The paper deals with an important topic in relation to health/safety in mining operations and the authors discuss the development of FTIR spectroscopy for the detection of carbonate minerals in coal mine dust samples. In my view, the article is of a satisfactory standard and the data was well presented. However, there is room for further improvements and below are some comments which I believe can be handled as a minor revision.
- In the experimental section 2.1 no mention was made in relation to the number of scans used to collect the infrared spectra. This is an important parameter and there is no discussion of it in terms of an optimum value for FTIR analysis of RD? The authors should provide more information on this.
- Following on from the above comment was any effort made in improving the limit of detection of FTIR for calcite? It seems to me that the LOD for a lot of the samples (particularly the RS) was unsuitable. Some comments regarding how the detection limit could be improved would be useful.
- Did the authors look at using the absorption band around 1400 cm-1 due to the C-O stretching vibration of the carbonate ion? How does it compare to the peak at 877 cm-1? The 1400 cm-1 band may be useful considering that some of the samples contained dolomite and its absorbance/intensity is generally greater than the others. It would be good if the authors can add a comment around why the peak at 1400 cm-1 was not used.
- Finally, how does this study compare to others that have used FTIR spectroscopy for various dust particles? The authors may want to consider the paper by Stach et al. Analytical and Bioanalytical Chemistry, 2020, 412, 3499-3508.
Author Response
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Reviewer 3 Report
Direct-on-filter FTIR Spectroscopy to estimate calcite as a proxy for limestone ‘rock dust’ in respirable coal mine dust samples is very interesting paper. Some improvement is required.
Line 8; Application of fine (nanosized or submicron?), inert ‘rock dust’ (RD) to the surfaces in underground coal mines..
Line 9: However, due to its size (and composition?), RD has ...
Line 14: limestone and calcite (calcium carbonate) or limestone (calcium carbonate) and calcite (calcium carbonate)
Line 35: In addition to being inert, RD products must also have relatively fine particle size to be effective (for which application). This sentence is not complete.
Line 39: Since finer coal dust has more surface area,... Please to give an precise information about a surface area value.
Line 47: the respirable crystalline silica (RCS) content was proposed to be the most likely cause (for silicosis-lung disease). Is amorph silica also a danger for our health.
Line 73: estimating calcite (no analysis for silica?) as a proxy for RD in RCMD samples...
line 74, 75: with laboratory- generated samples (please to check a writing of this sentence)
line 111: powdered material was aerosolized in a sealed enclosure using compressed air. What was the final aerosol size?
Line 204 (Table 3): Particle size to mass assumptions (please to give an unit for this ratio µm/g?)
Line 235 (Figure 2): (a) TGA- Please to give an information about TGA (heating rate, atmosphere, temperature interval, mass of sample)
Line 251: it was observed that the coal did not completely oxidize in the expected temperature range. Please to give an information about protecting atmosphere (argon or air or oxygen) and temperature range (25-1000°C)
Line 279: Figure 3. Comparison of FTIR-based calcite mass % and (a) TGA- or (b) SEM-EDX-based carbonate mineral mass % ... (please to add an information about conditions for TGA-Analysis
References:
Please to check the writing of references. It shall be uniform.
Line 423, 424: Phillips, K.; Keles, C.; Scaggs-Witte, M.; Sarver, E. COAL AND MINERAL MASS FRACTIONS IN PERSONAL RESPIRABLE DUST SAMPLES COLLECTED BY CENTRAL APPALACHIAN MINERS. MINING ENGINEERING 2018, 70,
Line 425, 426: 18. Miller, A.L.; Drake, P.L.; Murphy, N.C.; Noll, J.D.; Volkwein, J.C. Evaluating portable infrared spectrometers for measuring the silica content of coal dust. J Environ Monit 2012, 14, 48-55, doi:10.1039/c1em10678c.
General remarks:
- if you use TGA analysis please to include chemical equations regarding determination of calcite.
- Did you perform XRD-analysis od sample before and after TGA-analysis
- Figure 3, TGA Carbonate % at Y axis (is better to write TGA Carbonate mass %.)
- How is possible to use SEM- Analysis for quantitative analysis of calcite (maybe it is SEM/EDX analysis?)
Author Response
Please see the attachment.
Author Response File: Author Response.docx
