Flash Calcination of Kaolinite Clay in a Pilot Reactor: Evaluation of Clay Color Change in Oxidizing, Inert and Reducing Atmospheres

Authors

  • Gabriel Henrique Wienhage

    University of Blumenau, Chemical Engineering Post-Graduation Program, São Paulo Street, 3250, Blumenau, SC 89030-000, Brazil
  • Vinícius Henrique de Freitas

    Dynamis Engineering and Commerce, São Paulo, SP 05024-030, Brazil
  • Julio Zeppone Carlos

    Dynamis Engineering and Commerce, São Paulo, SP 05024-030, Brazil
  • Luis Filipe von Rainer Fabiani

    Dynamis Engineering and Commerce, São Paulo, SP 05024-030, Brazil
  • Luiz Felipe de Pinho

    Dynamis Engineering and Commerce, São Paulo, SP 05024-030, Brazil
  • Rodrigo de Souza Borges

    Dynamis Engineering and Commerce, São Paulo, SP 05024-030, Brazil
  • Vinicyus Rodolfo Wiggers

    University of Blumenau, Chemical Engineering Post-Graduation Program, São Paulo Street, 3250, Blumenau, SC 89030-000, Brazil

DOI:

https://doi.org/10.30564/jbms.v7i1.8104
Received: 17 December 2024 | Revised: 5 January 2025 | Accepted: 13 January 2025 | Published Online: 10 March 2025

Abstract

Cement production, while essential for global infrastructure, contributes significantly to carbon dioxide emissions, accounting for approximately 7% of total emissions. To mitigate these environmental impacts, flash calcination of kaolinitic clays has been investigated as a sustainable alternative. This technique involves the rapid heating of clays, enabling their use as supplementary cementitious materials. The primary objective of this study was to modify the color of calcined clay in various atmospheres (oxidizing, inert, and reducing) to achieve a grayish tone similar to commercial cement while preserving its reactive properties. The experimental procedure employed a tubular reactor with precise control of gas flows (atmospheric air, nitrogen, and a carbon monoxide–nitrogen mixture). Physicochemical characterization of the raw clay was conducted before calcination, with analyses repeated on the calcined clays following experimentation. Results indicated that clay calcined in an oxidizing atmosphere acquired a reddish hue, attributed to the oxidation of iron in hematite. The Clay exhibited a pinkish tone in an inert atmosphere, while calcination in a reducing atmosphere yielded the desired grayish color. Regarding pozzolanic activity, clays calcined in oxidizing and inert atmospheres displayed robust strength, ranging from 82% to 87%. Calcination in a reducing atmosphere resulted in slightly lower strength, around 74%, likely due to the clay’s chemical composition and the calcination process, which affects compound formation and material reactivity.

Keywords:

Flash Calcination; Kaolinite Clay; Reducing Atmosphere; Reduction of Hematite

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How to Cite

Wienhage, G. H., Freitas, V. H. de, Carlos, J. Z., Fabiani, L. F. von R., Pinho, L. F. de, Borges, R. de S., & Vinicyus Rodolfo Wiggers. (2025). Flash Calcination of Kaolinite Clay in a Pilot Reactor: Evaluation of Clay Color Change in Oxidizing, Inert and Reducing Atmospheres. Journal of Building Material Science, 7(1), 73–82. https://doi.org/10.30564/jbms.v7i1.8104

Issue

Vol. 7 , Iss. 1 (March 2025): In Progress

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Article

License

Copyright © 2025 Gabriel Henrique Wienhage, Vinícius Henrique de Freitas, Julio Zeppone Carlos, Luis Filipe von Rainer Fabiani, Luiz Felipe de Pinho, Rodrigo de Souza Borges, Vinicyus Rodolfo Wiggers

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This is an open access article under the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) License.

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