Synthesis of Ye’elimite from Anthropogenic Waste

Round 1

Reviewer 1 Report

This manuscript does an excellent job demonstrating the possibility of synthesizing and obtaining ye'elimite from waste materials of anthropogenic origin. It is a well-written, needed, and valuable paper that can provide useful information about waste safe recycling. However, some revisions are needed as follows:

1.     Three line tables should be used for all tables, which should be unified. The size and layout of tables also need to be unified.

2.     The size and layout of the pictures need to be reasonable. The current pictures have different sizes and look very messy. In addition, each picture needs to be marked with the core content you want to express.

3.     For Figure 5, there is also a logo in the upper right corner, which needs to be deleted, and the image processing needs to be more careful.

4.     For Figure 6, it is necessary to find a suitable angle for shooting. It is difficult to see whether the size of each sample is uniform in the current picture.

5.     The current conclusions are well summarized, but you need to specifically list about three conclusions you have obtained from the research.

6.     As for the XRD results, I see that your marks are complete, but my question is whether these phases are highly matched, which needs to be determined again.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

  The article is important, interesting and well-prepared. The introduction should be slightly modified because it contains understatement or overestimation of profits.

1. Introduction

Although the content is focused on the characteristics of CSA cement, the authors use the term hazardous waste recycling in the description of the experiment. This applies to e.g. waste containing asbestos, waste with a large mass, and significant spread. In practice, their problems have not been solved by recycling on an industrial scale, although in some countries their thermal decomposition is used to a small extent, e.g. in the production of ceramics. This waste poses a significant environmental risk with any treatment. The lack of brief information about this in the introduction gives the impression that there is no such problem.

Two solutions for the introduction would be suggested:

- Missing the purpose of this method as recycling. The description of the experiment and the resulting goal are obvious and they  "defend themselves" without claiming the advantages of the process. I believe that at the stage of laboratory research and scientific article, it is justified.

Or

- If the authors develop the theme of recycling, they should write about the risk of releasing asbestos fibres into the environment in such a process.

A lack of such information may suggest to the reader that the risk does not exist. Meanwhile, every "action" with asbestos-containing waste carried out on a technical scale or even more so in the production industry (including waste extraction, transport, application to devices, and thermal treatment) release asbestos dust into the environment. Asbestos-cement components have different thermal expansion. During calcination, a dynamic physical disintegration of the material occurs and the release of asbestos fibres into the air before they are changed into a new mineral phase in the main mass of the waste. For example, an experimental device for thermal destruction of asbestos created around itself air pollution with 10⁶ f/m³ rspirable asbestos fibres during operation.

A scientific article describing a laboratory experiment is not required to deal with the technical problems of large-scale processes, including the issue of economics or energy savings of this process. In this case, double calcination, first of the waste and then of the cement components, does not suggest energy savings. All the more so, in my opinion, the authors should reduce the process described in the introduction to the necessary minimum, as they did in the case of conclusions.

2. Materials and methods

CSA cement has a different chemical and phase composition than Portland cement. Their comparison is less interesting than other high alumina cement, CAC. Was, for example, a comparison with GÓRKAL cement considered? What would the product described by the authors look like in relation to the standard requirements (PN-EN14647)?

Regarding safety: was the concentration of asbestos dust in the air recorded in the environment during the thermal decomposition phase of waste a-c?

3. Result and discussion. Perfectly described. No comments.

4. Conclusions Specific, synthetic in a positive sense. No comments.

It is worth adding a word about the direction of further research.

Author Response

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Author Response File: Author Response.docx