Industrial Kaolin Waste as Raw Material in the Synthesis of the SAPO-34 Molecular Sieve

Pinheiro, Darllan do Rosário; Gonçalves, Leonardo Rodrigues; Sena, Raimunda Lina Pacheco de; Martelli, Marlice Cruz; Neves, R. F.; Ribeiro, Nielson Fernando da Paixão

doi:10.1590/1980-5373-mr-2020-0043

Cited by 15 publications

(5 citation statements)

References 19 publications

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“…The amorphous band in the spectrum of G2C600 in this range is more pronounced than in G2, denoting a higher amount of amorphous gel correlated to a better reticulation of samples during the geopolymerization process. This last observation is coherent with the examples reported in the literature for a typical AAM amorphous pattern indicative of a geopolymeric gel [ 51 , 52 ]. Therefore, it can be affirmed that the investigated clay by-product requires at least 600 °C calcination temperature to reach an efficient consolidation in an alkaline environment.…”

Section: Resultssupporting

confidence: 92%

Mine Clay Washing Residues as a Source for Alkali-Activated Binders

Sgarlata

Formia²,

Siligardi

et al. 2021

Materials

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The aim of this paper is to promote the use of mine clay washing residues for the preparation of alkali activated materials (AAMs). In particular, the influence of the calcination temperature of the clayey by-product on the geopolymerization process was investigated in terms of chemical stability and durability in water. The halloysitic clay, a mining by-product, has been used after calcination and mixed with an alkaline solution to form alkali activated binders. Attention was focused on the influence of the clay’s calcination treatment (450–500–600 °C) on the geopolymers’ microstructure of samples, remaining in the lower limit indicated by the literature for kaolinite or illite calcination. The mixtures of clay and alkali activators (NaOH 8M and Na-silicate) were cured at room temperature for 28 days. The influence of solid to liquid ratio in the mix formulation was also tested in terms of chemical stability measuring the pH and the ionic conductivity of the eluate after 24-h immersion time in water. The results reported values of ionic conductivity higher for samples made with untreated clay or with low temperature of calcination (≥756 mS/m) compared with values of samples made with calcined clay (292 mS/m). This result suggests that without a proper calcination of the as-received clay it was not possible to obtain 25 °C-consolidated AAMs with good chemical stability and dense microstructure. The measures of integrity test, pH, and ionic conductivity in water confirmed that the best sample is made with calcined clay at 600 °C, being similar (53% higher ionic conductivity of the eluate) or equal (integrity test and pH) to values recorded for the metakaolin-based geopolymer considered the reference material. These results were reflected in term of reticulation and morphology of samples through the analysis with scanning electron microscope (SEM) and X-ray diffraction (XRD), which show a dense and homogeneous microstructure predominantly amorphous with minor amounts of quartz, halloysite, and illite crystalline phases. Special attention was dedicated to this by-product to promote its use, given that kaolinite (and metakaolin), as primary mineral product, has a strong impact on the environment. The results obtained led us to consider this halloysite clay very interesting as an aluminosilicate precursor, and extensively deepening its properties and reactivity for the alkaline activation. In fact, the heart of this work is to study the possibility of reusing this by-product of an industrial process to obtain more sustainable high-performance binders.

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Section: Resultssupporting

confidence: 92%

Mine Clay Washing Residues as a Source for Alkali-Activated Binders

Sgarlata

Formia²,

Siligardi

et al. 2021

Materials

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“…As depicted in Figure 2, there is an amorphous phase at 25-35 • and the main crystalline phases of slag are merwinite (Ca 3 MgSi 2 O 8 , ICSD #26002), gehlenite (Ca 2 Al 2 SiO 7 , ICSD #158171), and quartz (SiO 2 , ICSD #174). In addition, there is less crystalline phase (Anatase, ICSD #1272) in metakaolin and an amorphous phase at 15-35 • attributed to amorphous kaolinite [27], indicating the high reactivity of metakaolin.…”

Section: Raw Materialsmentioning

confidence: 99%

Understanding the Role of Metakaolin towards Mitigating the Shrinkage Behavior of Alkali-Activated Slag

Cheng

Han

et al. 2021

Materials

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This research investigates the mechanism of metakaolin for mitigating the autogenous and drying shrinkages of alkali-activated slag with regard to the activator parameters, including concentration and modulus. The results indicate that the incorporation of metakaolin can decrease the initial viscosity and setting time. Increasing activator concentration can promote the reaction process and shorten the setting time. An increase in the metakaolin content induces a decrease in compressive strength due to reduced formation of reaction products. However, increasing activator dosage and modulus can improve the compressive strength of alkali-activated slag containing 30% metakaolin. The inclusion of metakaolin can mitigate the autogenous and drying shrinkage of alkali-activated slag by coarsening the pore structure. On the other hand, increases in activator concentration and modulus result in an increase in magnitude of the autogenous and drying shrinkage of alkali-activated slag containing metakaolin. The influence of the activator modulus on the shrinkage behavior of alkali-activated slag-metakaolin binary system should be further investigated.

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“…The calcination stage was found to be effective, and the de-hydroxylation process destroyed the kaolinite structure. As a result, an amorphous material was identified by an increase in the diffractogram background, as previously described [33,34]. In this work, amorphous silica was produced by calcining filter cake at 600 °C/2h followed by water quenching.…”

Section: Phase Identification Of Post-treated Filter Cake (Mk)mentioning

confidence: 80%

Utilization of silica-enriched filter cake industry by-products as partial ordinary portland cement replacement

Bereda

Tesfamariam²,

Desissa³

et al. 2023

Mater. Res. Express

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In recent years, industrial byproducts have been converted into useful and valuable commercial items. Reusing these byproducts plays a crucial role to ensure the circular economy and thereby safeguard the environmental impacts. In Ethiopia, the Aluminate Sulphate chemical factory disposes of filter-cake waste materials in landfills that have high silica content. The factory is using pure kaolin and other raw materials for the production of Aluminum Sulphate and Sulphuric Acid by burning at high temperatures. By-products materials were collected from the factory and then calcined (post-treated) at 600 ℃ for 2h in a muffle furnace. From Atomic Absorption Spectrometry measurement result, we it is confirmed that the post-treated (at 600 ℃/2h) silica-enriched filter-cake waste materials have a similar composition to Metakaolin (MK). Post-treated filter cake (named MK) became more amorphous having high reactive silica with very low impurities as it was calcined and quenched rapidly. In this study, the properties of blended Ordinary Portland Cement (OPC)-mortar samples were investigated with the addition of heat-treated filter cake waste materials (0-20%) as a partial OPC replacement. X-ray diffraction, Fourier Transform-Infrared Spectroscopy, Differential Thermal Analysis, Scanning Electron Microscope, and Atomic Absorption Spectrometry were used to investigate the properties of mortar samples that contain post-treated filter-cake (MK) materials and OPC-cement. The flexural and compressive strengths of 10% MK+90% OPC-mortar samples were enhanced at early curing ages, 7 & 28 days. Moreover, the flexural and compressive strengths of OPC mortars with 15% MK have been improved at 28 days of curing age. However, 20% MK+80% OPC blended mortars have not shown any improvement in mechanical properties. Setting time, soundness, water absorption, and apparent porosity of cement pastes with the addition of post-treated filter cake (MK) are also analyzed.

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Industrial Kaolin Waste as Raw Material in the Synthesis of the SAPO-34 Molecular Sieve

Cited by 15 publications

References 19 publications

Mine Clay Washing Residues as a Source for Alkali-Activated Binders

Mine Clay Washing Residues as a Source for Alkali-Activated Binders

Understanding the Role of Metakaolin towards Mitigating the Shrinkage Behavior of Alkali-Activated Slag

Utilization of silica-enriched filter cake industry by-products as partial ordinary portland cement replacement

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