A Mössbauer spectroscopy study of the transformation of iron compounds in clay materials

Абдрахимова, Е. С.; Abdrakhimov, V. Z.

doi:10.1134/s0036024406070132

Cited by 6 publications

(6 citation statements)

References 34 publications

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“…Their presence could not be determined by XRD in our nano-/microscale separate, because the sample was purposely chosen in such a way that it visually exhibited as small amounts as possible of such contamination. However, their presence cannot also be excluded and could be correlated to the high Fe contents found from the SEM-EDX measurements, beside the Fe substitute in montmorillonite [62].…”

Section: Summary Discussionmentioning

confidence: 99%

Mineralogical and Physico-Chemical Characterization of the Oraşu-Nou (Romania) Bentonite Resources

Damian

Szakács

et al. 2021

Minerals

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The objective of this study is to describe the mineralogical composition and chemical properties of the Oraşu Nou bentonite, from northwestern Romania. For mineralogical determinations, the following were used: X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FR-IR), thermogravimetric analysis, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). The chemical compositions and physical properties of the bentonites and bentonitized rocks were also determined. Calcium type montmorillonite is the predominant mineral in this deposit. Its average mass fraction is between 35% and 75%, reaching up to 95%. A small amount of halloysite and very fine cristobalite were also identified in the fine fraction. Quartz, feldspar, and kaolinite were identified as impurities. The average pH of natural bentonite is 6.2. Its cation exchange capacity (CEC) is in the lower-middle range for smectites at 45.89 cmol/kg, absorption capacity 43.58 mL/g, swelling degree 9.41%. Because of the high amounts and purity of montmorillonite, the valuable component mineral, the way is open to an easy refinement of this important resource. This way very high-quality colloidal suspensions can be obtained which can be used in the most modern applications of micro- and nanostructured materials.

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Section: Summary Discussionmentioning

confidence: 99%

Mineralogical and Physico-Chemical Characterization of the Oraşu-Nou (Romania) Bentonite Resources

Damian

Szakács

et al. 2021

Minerals

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“…Clay materials can contain up to 15 wt. % of iron oxide phases, and contents above 5% Fe 2 O 3 promote a reddish or pinkish colour of raw and calcined clays [121][122][123]. Cement producers may avoid selling cement with a colour different from the traditional grey, mainly for marketing purposes [95,120].…”

Section: Colour Controlmentioning

confidence: 99%

Clay calcination technology: state-of-the-art review by the RILEM TC 282-CCL

et al. 2021

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The use of calcined clays as supplementary cementitious materials provides the opportunity to significantly reduce the cement industry’s carbon burden; however, use at a global scale requires a deep understanding of the extraction and processing of the clays to be used, which will uncover routes to optimise their reactivity. This will enable increased usage of calcined clays as cement replacements, further improving the sustainability of concretes produced with them. Existing technologies can be adopted to produce calcined clays at an industrial scale in many regions around the world. This paper, produced by RILEM TC 282-CCL on calcined clays as supplementary cementitious materials (working group 2), focuses on the production of calcined clays, presents an overview of clay mining, and assesses the current state of the art in clay calcination technology, covering the most relevant aspects from the clay deposit to the factory gate. The energetics and associated carbon footprint of the calcination process are also discussed, and an outlook on clay calcination is presented, discussing the technological advancements required to fulfil future global demand for this material in sustainable infrastructure development.

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“…Iron oxide is the primary colorant in the clay materials. Most clay materials contain more than 5% Fe 2 O 3 , mainly as impurities which strongly influence the reddish color of clays [15,16]. This can affect their industrial application, in fine ceramic, paper, pigment industries, and civil construction [18].…”

Section: The Role Of Iron In Claysmentioning

confidence: 99%

“…In a low oxygen environment, hematite is reduced to form magnetite, which can be stable even at temperatures close to 300 °C [27][28][29] (see Fig. 1) For temperatures above 650°C, regardless the presence of oxygen, the main iron phase formed is magnetite [16,22,28,30].…”

Section: Color Control During Clay Calcinationmentioning

confidence: 99%

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Color control in industrial clay calcination

Hernández

Almenares-Reyes²,

Zunino

et al. 2020

RILEM Tech Lett

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The combined use of calcined clays and limestone in the ternary system LC3 enables up to 50% of clinker substitution without affecting the performance. Low grade calcined clays are rich in iron. If calcined in an oxygen rich atmosphere, they turn to red. Cement producers avoid selling cement with a color different to the traditional. This paper proposes a method to modify color during calcination by controlling the atmosphere during the cooling. At calcination, the high temperature favors the formation of magnetite even at oxidizing conditions. However, during the cooling phase, magnetite can convert back to hematite if oxygen is available and the calcined material will have a reddish color. The procedure to control color consists of injecting liquid fuel at the carcass of the kiln while the calcined material exits, so that it combusts and exhausts the oxygen available during the cooling process. The procedure was successfully implemented at a pilot kiln in India. Controlling the calcination atmosphere enabled the production of a black calcined clay, instead of a red material. The reactivity and properties of both red and black clay are very similar, and no side effects have impacted properties of LC3 cements produced with the treated clay.

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A Mössbauer spectroscopy study of the transformation of iron compounds in clay materials

Abstract: Palabras Clave: Activación térmica de arcillas, Material cementante suplementario, Geología de arcillas, Atmósfera y temperatura de calcinación, Desempeño de arcillas en morteros, Machine learning, Analítica de datos, Random forest, Big data.

Cited by 6 publications

References 34 publications

Mineralogical and Physico-Chemical Characterization of the Oraşu-Nou (Romania) Bentonite Resources

Mineralogical and Physico-Chemical Characterization of the Oraşu-Nou (Romania) Bentonite Resources

Clay calcination technology: state-of-the-art review by the RILEM TC 282-CCL

Color control in industrial clay calcination

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