Linking Automated Scanning Electron Microscope Based Investigations to Chemical Analysis for an Improved Understanding of Ash Characteristics

Round 1

Reviewer 1 Report

Manuscript ID: minerals-1330612

Title: Fine-grained and largely amorphous: Ash analysis

Authors: Andrea C. Guhl et al.

Title. The title does not explain this study. It is necessary to improved title, title must answered fo following questions: What? How? and What for was investigated?

Line 19-60 and 91-102. This is the same text.

Introduction. Authors must add more detail information about novelty of this research.

Figure 2. The authors just inserted the figures that the software for the analysis of XRD spectra produces. Authors should redraw the XRD peaks in the OriginPro software. In the captions to the name of minerals, interlinear numbers for metals must be observed.

Figure 3-4. Why authors used figure to show chemical compositions of three samples of ash? It is necessary to use Table for major and minor elements. What’s the LOI and carbon content in the samples?

Figure 5. Use different colors for curves. Topic must be improved.

Technical errors:

The references in the text must be changed from () to [].

The list of references is not in Minerals style https://www.mdpi.com/journal/minerals/instructions

 

This article focuses on a simple ash analysis. There are no new analytical methods or ash utilization methods. The article is poorly framed. There are repeated parts of the text, figures and references are badly designed. The scientific value of this article is practically equal to zero, since it does not provide new knowledge in the field of ash utilization or ash application. If the authors planned to show the possibility of using this ash as fertilizer, then it is necessary to make appropriate experiments. In this form, it is simply an analysis of XRD, LD, and analytic chemistry of three ash samples.

In this form article does not correspond to the Minerals level and should be rejected.

Author Response

Please see document

Author Response File: Author Response.docx

Reviewer 2 Report

Overall, This paper investigate compared ash analysis techniques and highlighted the relative strengths and weaknesses. It is helpful to investigate their potential for phosphorous recovery and efficient uses. However, the following are my suggestion to improve the manuscript:

1.The title is not appropriate. The main content of this paper is ash analysis techniques, the “Fine-grained and largely amorphousthe” is only the characteristics of ash, which cannot reflect the content of the article.
2.The Abstract needs to be restructured as in its present form it is confusing and unintelligible. It should be structured according to the following sequence:
- Objectives pursued in the research.
- Presentation of the general idea
- Objectives
- Methods and results achieved
- A few words to say how the results obtained will be applied. 
3.Subsection 1: The content of the Introduction is repeated completely, please delete.
4.Many references are missing in the Introduction. Rewrite.
5.References are missing in the Discussion of the results. The Results and Discussion should always be compared with those of other author.
6.The author compared different analysis methods, But there should be a discussion on various methods and research results.
7.In the conclusion, the authors should summarize the research from
both theoretical significance and practical significance, and puts forward the research shortcoming and future research direction. Please make it more concise.
8.Is the research purpose of this paper just to compare ash analysis techniques? Is there anything else, please refine.

Author Response

Please refer to document prepared

Author Response File: Author Response.docx

Reviewer 3 Report

Linking Automated SEM Investigations to Chemical Analysis
for an Improved Understanding of Ash Characteristics is very interesting paper. Some improvement are required.

Line 3: Is Title "Linking Automated SEM Investigations to Chemical Analysis
for an Improved Understanding of Ash Characteristics" suitable for this paper? I did not see SEM-analysis in your work. What is morphology of particles? Can you include one SEM-picture in this work?

Please to write full name for SEM in your Title.

 

 Line 19: Three samples have been studied in this comparison (which type of samples (ores? concentrates? SSA)

Line 20: SSA and highlighting strengths (please to write full name for SSA)

Line 32: SSA recycling (please to write full name for SSA at the beginning of this abstract)

Line 156: The qualitative analysis was assessed with the use of the DIFFRACplus EVA software (no possibility to use and discuss a Rietveld quantitative analysis?)

Line 298: Figure 4. Trace element contents as determined by ICP-OES and XRF measurements, averages of three measurements ( what is with analysis of trace content of of vanadium and yttrium)

 

Please to include the next paper in your reference in order to explain morphology of fly ash:

Effectiveness of Fly Ash and Red Mud as Strategies for Sustainable Acid Mine Drainage Management
Viktoria Keller, Srecko Stopic, Buhle Xakalashe, Yiqian Ma, Sehliselo Ndlovu
Brian Mwewa, Geoffrey S. Simate and Bernd Friedrich 

Minerals 2020, 10, 707; doi:10.3390/min10080707

Author Response

Please see file attached.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors' answers and the new version of the article were analyzed in detail. I strongly disagree with the authors and still consider this article doesn't correspond to the Minerals level and must be rejected.

I will give an explanation:

1. The authors cite a quote “We, geotechnical engineers, have to improve our skills for the chemical analysis!” from scientists of 2000 years article. Firstly, this is a scientific article, there is no need to add an emotional quote here. Secondly, this article was published 21 years ago. Since the methods of analysis have improved significantly. Especially analytical chemistry. Currently, there is no problem analyzing ash from any kind of raw material. There are many methods that allow to accurately determine both macro and micro components.
There is no novelty or original idea in this article.

2. The authors made blocks and analyzed them by SEM to calculate the chemical composition of the ash. What is the novelty here? In my work, I do similar analyzes every day. This is an approximate composition, not accurate. More accuracy can get by ICP. Why compare these methods if one method is obviously much more accurate than the other?

3. The article contains direct inconsistencies and errors. Figure 2 - why are on the figures hematite is written as iron oxide? Why is there no phase name signature for Ca9Al(PO4)7 and  Ca9Fe(PO4)7?

If we analyze the XRD composition of the ash and the chemical composition in Figure 3, then discrepancies are visible. For example, there are practically no iron phases in the Chemnitz sample. In Fig. 3b, iron is 12 wt%, silicon is only 14-15%, and most of all calcium is 15-16 wt%. It can be seen from the XRD data that the main part should be in silicon, not Fe and Ca.
Figure 3 doesn't contain any ICP for Si content at all.
The histograms themselves are gray, color them.
The authors did not provide the content of sodium (Na), potassium (K), magnesium (Mg), titanium (Ti).

4. Figure 4 does not contain arsenic (As) and mercury (Hg) by ICP. There are no error bars. The authors made a break on the contents of nickel (Ni), lead (Pb), chromium (Cr). Their concentration is not clear from the figure. Figures 4 a, b are of very poor quality compared to Figure 4c.

5. If the authors do not want to use tables of the chemical composition of ash, then they must sign the values ​​on each column in Figures 3,4.

6. Why need to compare particle sizes distribution by SEM and laser diffraction methods? These values ​​are significantly different. The SEM cannot make the calculation more accurate. SEM can be used to analyze water-soluble crystals.

7. The authors made an SEM of large blocks. Where are the SEM-images examples of ash samples? There are no SEM images in the article.

8. The authors in their response provided links to very old articles and patents (1995-2003). These articles do not prove anything. Authors must cite the links of 2020-2021, where there is a problem of ash analysis.

Author Response

please see file attached.

Author Response File: Author Response.docx