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12 pages, 2636 KiB

Open AccessArticle

Thermal Behavior of Ceramic Bodies Based on Fly Ash and Smectites

by Eva Plevová and Lenka Vaculíková

Minerals 2024, 14(4), 334; https://doi.org/10.3390/min14040334 - 25 Mar 2024

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Clay minerals have a great influence on the resulting properties of ceramic bodies. Fly ash as a waste material from burning black coal in power plants is a potentially valuable source of oxides (Al₂O₃, SiO₂ or Fe₂ [...] Read more.

Clay minerals have a great influence on the resulting properties of ceramic bodies. Fly ash as a waste material from burning black coal in power plants is a potentially valuable source of oxides (Al₂O₃, SiO₂ or Fe₂O₃) for this production. Considering the process of ceramic firing, it is important to understand the thermal behavior of individual ingredients. The thermal behavior of natural smectite minerals (montmorillonite, beidellite, hectorite and nontronite) and their mixtures with added fly ash at different ratios (10%, 30% and 50%) was investigated. The phase analysis was obtained using X-ray diffraction and FT-IR spectroscopy. Under heating to 1200 °C, the structural changes of smectites were divided into four steps including dehydration, dehydroxylation, decomposition and crystallization of new phases. The addition of fly ash caused a shift in the reaction temperatures for all the mentioned phases. These changes were most noticeable for mixtures with hectorite; on the contrary, they were least noticeable for beidellite mixtures. Total mixture mass loss continually decreased with increasing fly ash amount. The obtained experimental thermal data can be applicable not only in the production of ceramic bodies or energy waste processing but also in construction and ensuring the safety of municipal waste landfills. Full article

(This article belongs to the Special Issue Clay Minerals and Waste Fly Ash Ceramics, Volume II)

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16 pages, 3292 KiB

Open AccessArticle

Clay/Fly Ash Bricks Evaluated in Terms of Kaolin and Vermiculite Precursors of Mullite and Forsterite, and Photocatalytic Decomposition of the Methanol–Water Mixture

by Marta Valášková, Veronika Blahůšková, Miroslava Filip Edelmannová, Lenka Matějová, Karel Soukup and Eva Plevová

Minerals 2023, 13(9), 1114; https://doi.org/10.3390/min13091114 - 23 Aug 2023

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Abstract

This study focused on mullite-based and forsterite-based ceramic bricks fired at 1000 °C from mixtures of fly ash (40 mass%) and kaolins or vermiculites (60 mass%). The structural, physical, and mechanical properties were characterized by X-ray powder diffraction, nitrogen physisorption, mercury porosimetry, thermogravimetry, [...] Read more.

This study focused on mullite-based and forsterite-based ceramic bricks fired at 1000 °C from mixtures of fly ash (40 mass%) and kaolins or vermiculites (60 mass%). The structural, physical, and mechanical properties were characterized by X-ray powder diffraction, nitrogen physisorption, mercury porosimetry, thermogravimetry, and compressive strength. In the development of green-material-derived photocatalysts, we evaluated fly ash ceramic bricks based on kaolins and vermiculites, which deserve deeper research. Alkali potassium in the mixtures positively influenced the reduction of the firing temperature, shrinkage, small porosity, and high compressive strength of ceramic bricks. The crystallization of mullite in fly ash was observed on exotherm maxima from 813 to 1025 °C. Muscovite/illite admixture in kaolins precursor of mullite-based ceramics reduced the crystallization temperature of mullite by up to 70 °C. Vermiculite–hydrobiotite–phlogopite in mixed layers of a raw vermiculite precursor of forsterite-based ceramics controlled the formation of enstatite and forsterite in the temperature range from 736 ± 6 °C to 827 ± 6 °C. Mullite- and forsterite-based ceramic bricks were also investigated for photocatalytic hydrogen production. The photocatalytic generation of hydrogen in the presence of mullite-based ceramic bricks was positively correlated with the percentages of Fe₂O₃ in the lattice of mullites and in the presence of forsterite-based ceramics with the presence of diopside. Mullite-based ceramic produced the highest yield of hydrogen (320 µmol/g_cat after 4 h of irradiation) in the presence of mullite with the highest 10.4% substitution of Fe₂O₃ in the lattice. The forsterite-based ceramic produced the highest hydrogen yields (354 µmol/g_cat after 4 h of irradiation) over more active diopside than forsterite. Full article

(This article belongs to the Special Issue Clay Minerals and Waste Fly Ash Ceramics, Volume II)

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11 pages, 2040 KiB

Open AccessArticle

Infrared and Raman Spectroscopy of Mullite Ceramics Synthesized from Fly Ash and Kaolin

by Michal Ritz

Minerals 2023, 13(7), 864; https://doi.org/10.3390/min13070864 - 26 Jun 2023

Cited by 2 | Viewed by 1288

Abstract

Infrared spectroscopy and Raman spectroscopy were used to characterize mullite ceramics prepared from fly ash and kaolin by annealing at 1000 °C, 1100 °C, 1200 °C, and 1300 °C. IR spectroscopy confirmed the presence of SiO₄ tetrahedra and AlO₆ octahedra in [...] Read more.

Infrared spectroscopy and Raman spectroscopy were used to characterize mullite ceramics prepared from fly ash and kaolin by annealing at 1000 °C, 1100 °C, 1200 °C, and 1300 °C. IR spectroscopy confirmed the presence of SiO₄ tetrahedra and AlO₆ octahedra in samples. The presence of mullite has been confirmed at all temperatures. The presence of quartz has been confirmed up to a temperature of 1100 °C, and the presence of an amorphous form of SiO₂ has been confirmed at temperatures of 1200 °C and 1300 °C. The transformation of quartz into the amorphous form of SiO₂ at temperatures above 1100 °C is assumed. Transformation was performed on the percentage intensity decrease of the bending vibration of Si-O-Si (at about 450 cm⁻¹) and Al-O-Si (at about 550 cm⁻¹). Raman spectroscopy confirmed the presence of mullite at different stages of structural ordering (a well-ordered structure at a temperature of 1100 °C and a disordered structure at a temperature of 1300 °C). Full article

(This article belongs to the Special Issue Clay Minerals and Waste Fly Ash Ceramics, Volume II)

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9 pages, 424 KiB

Open AccessArticle

Study of Dendromass Ashes Fusibility with the Addition of Magnesite, Limestone and Alumina

by Pavol Vadász, Beatrice Plešingerová, Dávid Medveď, Gabriel Sučik, Radka Bakajsová and Vladimír Petrov

Minerals 2023, 13(5), 631; https://doi.org/10.3390/min13050631 - 30 Apr 2023

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Abstract

The fusibility of ash from woodchip combustion is characterised in the present work. The impact of the increase in MgO, CaO, and Al₂O₃ content in the bio-ash on the classification of ash into categories according to slagging and fouling indices [...] Read more.

The fusibility of ash from woodchip combustion is characterised in the present work. The impact of the increase in MgO, CaO, and Al₂O₃ content in the bio-ash on the classification of ash into categories according to slagging and fouling indices was evaluated. The ash was characterized based on the chemical composition using slagging and fouling indices. However, these ash composition changes did not assign the ash into categories of the indices F_U, S_R, R_S, and B/A (fouling, slagging, slag viscosity, basicity), with less ash inclination to slagging and fouling. The indices were primarily derived for ashes from coal combustion. The indices values characterizing the ash were compared with measured results of ash melting according to STN ISO 540. The measured ash fusibility values showed that the addition of magnesite, limestone, and alumina to dendro-ashes increases the DT (temperature of deformation), HT (temperature of hemisphere), and the AFI (ash fusibility index). There is no conformity between the values of the indices and the measurement of ash fusibility temperatures. In terms of temperatures in the combustion chamber, the measured sintering (T_sin) and DT are suitable for evaluating the tendency of ash to slagging and fouling as well as an accretion of ash particles sticking to the lining. Full article

(This article belongs to the Special Issue Clay Minerals and Waste Fly Ash Ceramics, Volume II)

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18 pages, 7492 KiB

Open AccessArticle

The Corrosion Effect of Fly Ash from Biomass Combustion on Andalusite Refractory Materials

by Jozef Vlček, Hana Ovčačíková, Marek Velička, Michaela Topinková, Jiří Burda and Petra Matějková

Minerals 2023, 13(3), 357; https://doi.org/10.3390/min13030357 - 03 Mar 2023

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Abstract

The main problem affecting the life of refractory linings in furnaces is alkaline corrosion formed during biomass combustion, especially in systems with SiO₂–Al₂O₃. This corrosion effect is very intensive compared to using conventional technologies designed for burning [...] Read more.

The main problem affecting the life of refractory linings in furnaces is alkaline corrosion formed during biomass combustion, especially in systems with SiO₂–Al₂O₃. This corrosion effect is very intensive compared to using conventional technologies designed for burning traditional fuels. This study focuses on the development of a new type of andalusite refractory material with a higher corrosion resistance to K₂CO₃ and fly ash after biomass combustion. The original andalusite refractory material is labeled A60PT0, with an oxide content of 60 wt.% Al₂O₃ and 37 wt.% SiO₂, a compressive strength parameter of 64 MPa, and an apparent porosity of 15%. In the experiment, four mixtures (labeled A60PT1–A60PT4) were modified primarily using the raw materials and granulometry. The fly ash was characterized by an X-ray diffraction analysis with the following phases: quartz, calcite, microcline, leucite, portlandite, and hematite. According to the X-ray fluorescence analysis, the samples contained the following oxides: 47 wt.% CaO, 12 wt.% K₂O, 4.6 wt.% SiO₂, 3.5 wt.% MgO, and some minority oxides such as P₂O₅, MgO, MnO, and Fe₂O₃ between 2 and 5 %. The tendency for slagging/fouling of the ash was determined with the help of the indexes B/A, TA, K_t, and Fu. The final material was a shaped andalusite refractory material labeled A60PT4 with a content of 65 wt.% Al₂O₃ and 36 wt.% SiO_2. The properties of the andalusite material were a compressive strength of 106.9 MPa, an apparent porosity of 13%, and the recommended temperature of use up to 1300 °C. For corrosion testing, a static crucible test was performed according to the norm ČSN CEN/TS 15418 and the company’s internal regulation. The exposure time of the samples was 2 h and 5 h at temperatures of 1100 °C and 1400 °C for K₂CO₃ and ash, respectively. For the evaluation of tested samples, an X-ray powder differential analysis, an X-ray fluorescence analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used. Full article

(This article belongs to the Special Issue Clay Minerals and Waste Fly Ash Ceramics, Volume II)

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17 pages, 3295 KiB

Open AccessArticle

Evaluation of Linamon Red Clay, Salvador Black Cinder and Kapatagan Diatomaceous Earth of the Southern Philippines

by Ivyleen C. Bernardo-Arugay, Fel Jane A. Echavez, Liberty R. Lumasag, Jade P. Cahigao, Elly U. Aligno, Jr., Roben Victor M. Dispo, Sherlyn Keh D. Dionio, Christian Julle C. Saladaga, Beverly L. Bato, Alyssa May Rabadon Simplicio and Raymond V. Rivera Virtudazo

Minerals 2023, 13(2), 252; https://doi.org/10.3390/min13020252 - 11 Feb 2023

Cited by 3 | Viewed by 4691

Abstract

The southern island of the Philippines is abundant in silicate minerals, including the province of Lanao del Norte. However, some of these resources in the region are untapped for use as raw materials in the production of various ceramic products for industrial, pharmaceutical, [...] Read more.

The southern island of the Philippines is abundant in silicate minerals, including the province of Lanao del Norte. However, some of these resources in the region are untapped for use as raw materials in the production of various ceramic products for industrial, pharmaceutical, and nanotechnology applications. These could include tiles, sanitary ware, dinnerware, insulating bricks, porcelain, membranes and coatings. Some of the explored minerals are the red clay in the municipality of Linamon, diatomaceous earth in Kapatagan and black cinder in Salvador. It is the aim of this study that these minerals are evaluated in terms of their physical and chemical properties so that these will be used for optimum application. The properties that were determined were their specific gravities, raw and fired surface colors, Atterberg limits, particle size distribution, thermal properties, morphologies and mineralogical compositions. Pellets were formed for each raw material and fired at two temperature levels 1000 °C and 1200 °C to evaluate their physical properties. Linamon red clay has a 38.88% cumulative passing size of 150 µm, and the black cinder of Salvador and diatomaceous earth of Kapatagan have cumulative passing sizes of 96.53% and 60.12% at 150-micron sieve, respectively. The common mineral contents of the three samples are montmorillonite, quartz and andesine. Black cinder fired at 1200 °C has the darkest shade of red with a greasy quasi-submetallic luster. It attained the highest fusion coverage on the platform among the three materials, which makes it a potential supplement or replacement for feldspar in clay-based triaxial materials for ceramic production. The diatomaceous earth has the potential to be a secondary clay content source and a good source of flux for a certain temperature range. Both the red clay and diatomaceous earth were classified as plastic materials that are suitable for brick production, and the red clay is also feasible for pottery production. These are a few of the features of the clay minerals in the region that present suitable properties for application as raw materials in the production of ceramic tiles and hollow ceramic products. Full article

(This article belongs to the Special Issue Clay Minerals and Waste Fly Ash Ceramics, Volume II)

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Review

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20 pages, 2230 KiB

Open AccessFeature PaperReview

Calcium Orthophosphate–Clay Composites—Preparation, Characterisation, and Applications: A Review

by Monika Šupová

Minerals 2024, 14(2), 169; https://doi.org/10.3390/min14020169 - 04 Feb 2024

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Abstract

Calcium orthophosphates and clays and their composites are one of the most important groups in the field of new, modern, and technologically advanced materials that are accessible, inexpensive, and environmentally friendly. This review provides a summary of recent research on calcium orthophosphate–clay composites, [...] Read more.

Calcium orthophosphates and clays and their composites are one of the most important groups in the field of new, modern, and technologically advanced materials that are accessible, inexpensive, and environmentally friendly. This review provides a summary of recent research on calcium orthophosphate–clay composites, their preparation, characterisation, and use in various applications. An introduction to the subject is followed by a detailed description of the chemical and physical properties of calcium orthophosphates, clays, and clay minerals. This is followed by a general summary of preparation methods for calcium orthophosphate–clay composites. Particular attention is paid to the description of individual applications, i.e., environmental applications, biomaterials science (tissue engineering, pharmacology), and other emerging applications. Finally, future perspectives are summarised and discussed. Full article

(This article belongs to the Special Issue Clay Minerals and Waste Fly Ash Ceramics, Volume II)

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24 pages, 4198 KiB

Open AccessReview

Applications of Clays in Nanocomposites and Ceramics

by Alena Kalendova, Jana Kupkova, Martina Urbaskova and Dagmar Merinska

Minerals 2024, 14(1), 93; https://doi.org/10.3390/min14010093 - 13 Jan 2024

Cited by 2 | Viewed by 1195

Abstract

Clays and clay minerals are common natural materials, the unique properties of which have attracted the interest of the industry, especially because these materials are easily available, cheap, and non-toxic. Clays and clay minerals are widely used in many applications, such as in [...] Read more.

Clays and clay minerals are common natural materials, the unique properties of which have attracted the interest of the industry, especially because these materials are easily available, cheap, and non-toxic. Clays and clay minerals are widely used in many applications, such as in ceramic production, in the clarification of liquids, pollutant adsorbers, filler in composites and nanocomposites, soil amendments, in pharmacy, etc. This review assesses the development in the area of clay application in nanocomposites and ceramics. The first part of this study covers polymer/clay nanocomposites. Topics of interest include nanofiller sources for polymer nanocomposites, the possible ways of clay modification, polymer/clay nanocomposite classification and their processing, and polymer matrix overview with possible enhancement of nanocomposite properties. Some of the applications have already been commercialized. Approximately 80% of the polymer/clay nanocomposites are destined for the automotive, aeronautical, and packaging industries. The second part of this study describes ceramic materials with a focus on silicate ceramics. Talc and kaolinite represent the main natural raw materials for traditional ceramic applications. Less traditional cordierite, steatite, and forsterite could offer property enhancement and seem to be useful in electronics, electrical engineering, catalysts, solar thermal storage, or medical applications. Full article

(This article belongs to the Special Issue Clay Minerals and Waste Fly Ash Ceramics, Volume II)

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