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. 2024 May 12;17(10):2287.
doi: 10.3390/ma17102287.

An Evaluation of the Radioactive Content of Ashes Obtained from the Use of Fuels from Recycled Materials by Co-Processing in the Cement Industry

José Antonio Suarez-Navarro  1 , Miguel Ángel Sanjuán  2 , Pedro Mora  3 , María Del Mar Alonso  4
Affiliations

An Evaluation of the Radioactive Content of Ashes Obtained from the Use of Fuels from Recycled Materials by Co-Processing in the Cement Industry

José Antonio Suarez-Navarro et al. Materials (Basel). .

Abstract

The co-processing of different wastes as fuels in the manufacture of cement clinker not only meets the objectives of a circular economy but also contributes to the reduction in CO2 emissions in the manufacture of Portland cement. However, waste used as alternative fuels, such as sludge or organic-rich residues, may contain naturally occurring radionuclides that can be concentrated during the combustion process. In this study, the presence of natural radionuclides (radioactive series of uranium, thorium, and 40K) and anthropogenic radionuclides (137Cs) in these wastes has been investigated by gamma spectrometry. Possible relationships between the radioactive content and the obtained chemical composition, determined by X-ray fluorescence, have also been studied by applying a principal component analysis (PCA). The results showed that the wastes with the highest radioactive content were sewage sludge with activity concentrations of 238U and 210Pb of 321 ± 38 Bq kg-1 and 110 ± 14 Bq kg-1, respectively. A correlation between radioactive content and Fe2O3 concentration was also observed. The annual effective dose rates to workers for the ashes estimated from the ash content ranged from 0.0033 mSv to 0.092 mSv and therefore do not pose a risk to workers as they are lower than the 1 mSv per year limit for the general public (DIRECTIVE 2013/59/EURATOM).

Keywords: XRF; cement; co-processing; gamma spectrometry; principal component analysis; recycled materials.

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Conflict of interest statement

The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Figures

Figure 1
Figure 1
Types of waste used, together with its nomenclature and the number of samples of each type.
Figure 2
Figure 2
The schematic of the measurement system (DSA-LX, HPGe gamma detector, dewar vessel filled with liquid nitrogen, lead shielding, Tien and Cooper shielding for Pb X-ray removal) and photopic of the gamma emitters of the three natural radioactive series, and 40K and 137Cs from the fallout. The values of energy and photons per 100 disintegrations were taken from the tables of the Laboratorie National Henri Becquerel [26].
Figure 3
Figure 3
Results of the principal component analysis (PCA) of the residues according to the chemical composition obtained by XRF: (a) the scree plot with the % of variance explained according to the factors obtained, (b) correlations obtained between the different variables according to the 2 most important factors, (c) percentage contribution of the different variables to factor 1, and (d) percentage contribution of the different variables to factor 2.
Figure 4
Figure 4
The contribution of the different samples to the factors with the highest GWP impact (48.1% and 18.4%, respectively). The dotted red line represents the expected average contribution (cutoff), with the columns shown for the two factors being those that exceeded this value.
Figure 5
Figure 5
The HJ-Biplot graph presents the results of the principal component analysis along with the confidence ellipses for the different groups of residuals analyzed. The scores obtained for the various samples are shown in circular shapes whose sizes represent their contributions to the different components.
Figure 6
Figure 6
The cluster map created from the results of the principal component analysis. The total number of clusters resulting from the analysis was six.
Figure 7
Figure 7
Increases in the activity concentration of radionuclides from the uranium (234Th, 226Ra, and 210Pb) and thorium (212Pb) series, along with 40K.
See this image and copyright information in PMC

References

    1. Viczek S.A., Aldrian A., Pomberger R., Sarc R. Determination of the material-recyclable share of SRF during co-processing in the cement industry. Resour. Conserv. Recycl. 2020;156:104696. doi: 10.1016/j.resconrec.2020.104696. - DOI - PMC - PubMed
    1. Alarcón A., Mora P., Vallina D., Martin M. Coprocesado: Recuperación material de la fracción mineral de los combustibles derivados de residuos en la industria cementera. Cemento Hormigón. 2023;1019:14.
    1. Xu J., Sun S.F., Karstensen K., Yan D.H., Peng Z. Co-Processing Hazardous Waste in the Chinese Cement Industry—Status 2014. Appl. Mech. Mater. 2015;768:679–686. doi: 10.4028/www.scientific.net/AMM.768.679. - DOI
    1. Kallio A., Virtanen S., Leikoski N., Iloniemi E., Kämäräinen M., Hildén T., Mattila A. Radioactivity of residues from waste incineration facilities in Finland. J. Radiol. Prot. 2023;43:021502. doi: 10.1088/1361-6498/acc596. - DOI - PubMed
    1. Carvalho F.P. Can the incineration of Municipal Solid Waste pose occupational and environmental radiation hazards? Int. J. Occup. Environ. Saf. 2017;1:1–10. doi: 10.24840/2184-0954_001.001_0001. - DOI