Clay Raw Materials Research Articles

Some Aspects Of Studying Clays For Producing Ceramic Brick Of Required Properties

This article aims to show what research needs to be carried out not only to understand the nature and establish the potential capabilities of clay raw materials, to guide technologists, what stages of testing should be organized in production and at what stages it is advisable to consult a specialist in order to develop a technically competent and optimal composition of ceramic bricks. A program for testing clay raw materials is described, which should be developed in such a way as to obtain the most complete information about this clay, its composition, properties, behavior during technological processing: molding, drying and firing during research. And also an explanation is given about the measures necessary before the start of the tests, it is advisable to have information about the geological surveys of the field, about the previously conducted studies and, if the plant has already been built and operated, about the problems that do not allow the production of products of the required quality.

Preparation of Low-Dielectric-Constant Kaolin Clay Ceramics by Chemical Cleaning Method

Kaolin clay is an inexpensive and abundant material with potential for use as a low-dielectric-constant ceramic; however, the natural metallic oxides the clay contains hinder such applications. In this study, kaolin clay ceramics with excellent physical and dielectric properties were synthesized using kaolin clay as the raw material by chemical cleaning and sintering. Characterization of the resulting samples showed that the sulfuric acid treatment has a significant influence on the metallic oxide content and dielectric properties of the kaolin clay ceramics. When the kaolin clay raw material was treated with sulfuric acid three times, the dielectric constant decreased from 5.12 to 3.75 and the Vickers hardness increased from 946 to 1,214 kg/mm2 relative to the ceramic prepared from the untreated clay. Therefore, these ceramics exhibit significant potential for use in the microelectronics industry.

Theoretical Assessment of the Prospects for the Use of Raw Materials in Ceramic Production

The paper presents the results of analyzing the prospects of using clay raw materials in a composition with metallurgical slags for the production of ceramic products. The results of the analysis of the chemical and mineralogical properties of clay from the Khalilovsky deposit in the Orenburg region and nickel slags from the dumps of the South Ural Nickel Combine are presented. The studies were carried out using X-ray fluorescence and differential thermal analysis methods. The article presents the performed X-ray and derivatograms of slag and clay and the features of the experimental types of raw materials revealed during their analysis. The connection between the chemical and mineralogical compositions of the experimental clay and slags on the technological properties of finished ceramic products has been theoretically established. The use of XRF and DTA to study the characteristics of plastic and non-plastic raw materials made it possible at the first stages of the experiment to reject materials that were unsatisfactory in properties for the production of ceramic products, which contributes to the optimization of experiments, rational consumption of costs of newly mined clay raw materials.

Influence of forming pressure on frost resistance of ceramics

The object of research is low-melting clays of the Kyiv region (Ukraine). The work is devoted to the study of obtaining ceramic materials resistant to low temperatures. Frost resistance is one of the most important characteristics for regions in which ceramic materials are used with frequent temperature transitions through 0 °C. The production of frost-resistant ceramic wall materials is determined by the type of raw materials and technological production parameters. The main technological methods for increasing frost resistance are: the use of less dispersed clays; batch homogenization; formation of raw material without textural defects and prevention of cracks during drying and firing. The work shows that the existing methods for increasing frost resistance can be implemented by reducing water absorption due to the creation of a microporous structure with predominantly closed pores by increased pressure of a semi-dry method of formation. An increase in the pressing pressure leads to an increase in the number of contacts of the molecules of the ceramic mass at the stage of formation. Due to this, the strength of the molded samples at a pressing pressure of more than 30 MPa is higher compared to samples molded by the plastic method. It was also found that an increase in the pressing pressure makes it possible to speed up the drying process of ceramic products, reducing energy consumption for their production. Due to an increase in the pressing pressure to 50 MPa, the strength of samples obtained by semi-dry pressing is 55.4 MPa, while for samples during plastic formation it is 22.9 MPa. Water absorption, on the contrary, for dry pressing is 9.3 %, while for plastic pressing it is 12.2 % at a firing temperature of 1000 °C. It is shown that increasing the pressing pressure is an effective way to improve the quality of ceramic materials based on local low-plasticity clay raw materials. Saving natural and energy resources, developing new sources of raw materials and comprehensive improvement of products with environmental friendliness of production remain important today.

Devising technology for utilizing water treatment waste to produce ceramic building materials

Based on the modern ideas about environmental protection, this paper reports a study into the utilization of water-treated waste from heavy metals (using copper(II) compounds as an example) for the manufacture of ceramic building materials. The examined clay minerals from local deposits and the optimal conditions for their heat treatment (at 1,100 °C) have been proposed for the sorption removal of pollutants of inorganic origin from wastewater. The use of wastewater after its treatment makes it possible to address several tasks at the same time: to protect the environment from pollution by technological wastewater, as well as to reuse wastewater in order to resolve the issue of water scarcity. Ceramic building materials were manufactured based on water purification waste (in the amount of 5 %) and clay raw materials. Their structural-mechanical and physicochemical characteristics have been comprehensively studied. Sintering processes begin at lower temperatures, which is why, with an increase in the annealing temperature to 1,000 °C and higher, their strength rapidly decreases. In the temperature range of 600‒1,100 °C, there are possibilities to apply ceramic technology to immobilize heavy metals in ceramic matrices. The prospect of utilizing water purification waste in the technological process of manufacturing inorganic ceramic materials has been shown. The safety of the building materials, manufactured by leaching pollutants from the ceramic samples using various aggressive environments (leaching to 6.4 %, 0.083 mg·cm2/day) has been investigated. The high strength and degree of the copper ion fixation in the structure of polymineral clay have been confirmed while secondary environmental pollution is almost absent

Acoustic control of the strengthening of building ceramics obtained by extrusion through an ultrasonic die

Extrusion through a die, vibrating with an ultrasonic frequency is a promising method for hardening ceramic materials (bricks, tiles, pipes, etc.). We present the results of studying low-frequency acoustic spectra of cylindrical samples of face brick ceramics reinforced by extrusion and addition of fiberglass waste. Correlations between structure changes in the obtained ceramics, parameters of the acoustic spectrum of the samples, and the destructive forces upon their compression (bending) in a press were analyzed. It is shown that ultrasonic extrusion increases the destruction force of the cylinders by 1 – 7 kN (~30 %) and thus shifts the frequency of the fundamental tones of transverse and longitudinal oscillations (6 and 17 kHz) with a coefficient of ~0.1 kHz/kN. The fiberglass particles strengthen the ceramics due to the formation of a needle-like crystalline bond during firing. At the same time, an increased addition of the fiberglass particles reduces the plasticity of the batch thus resulting in formation of the microcracks, cavities and internal stresses in the samples. The occurrence of internal defects shifts the frequency of longitudinal and transverse vibrations to a different extend, which can be used as an indicator of the defects present in the samples and provide the possible of their objective sorting and rejection. The vibration relaxation time (about 0.1 sec) does not change significantly under the described strengthening effects and being characterized by a wide scatter in each series of the samples cannot be considered an informative parameter. Thus, the effectiveness of the presented combined method of ceramics hardening can be accurately tested by the shift in the frequencies of longitudinal and transverse free vibrations of cylindrical specimens. The presented approach facilitates the process of developing new ceramic compositions and extrusion technology in conditions of depletion of sources of high-quality clay raw materials.

Technological properties of clay raw materials

The article summarizes and analyzes the technological characteristics of various clay raw materials. Recommendations on the feasibility of their use in various types of ceramic production are given. Their main characteristics are given, such as chemical composition, mineralogical and physical properties, which vary within extremely wide limits. They are most characterized by a layered structure. All clay minerals are considered as secondary geological formations that arose in deposits in which water was present as a product of changes in aluminosilicate rocks. Most clay minerals are the product of weathering and deposition, but they can also be formed in hydrothermal conditions.
 In addition to basic clay minerals, clays also contain various amounts of other minerals that often affect their behavior when used. The most common such minerals are quartz, feldspar and minerals containing iron, lime, alkalis and soluble salts. The organic component is also found in many clay deposits. Different classifications of clays are based on their geology, mineralogy, composition, properties and uses, but none of them covers all possible diversity.

Mineralogical and Microstructure Analysis for Characterization and Provenance of Ceramic Artifacts from Late Helladic Kastrouli Settlement, Delphi (Central Greece)

The present study deals with the characterization of a ceramic assemblage from the Late Mycenaean (Late Helladic III) settlement of Kastrouli, at Desfina near Delphi, Central Greece using various analytical techniques. Kastrouli is located in a strategic position supervising the Mesokampos plateau and the entire peninsula and is related to other nearby coeval settlements. In total 40 ceramic sherds and 8 clay raw materials were analyzed through mineralogical, petrographic and microstructural techniques. Experimental briquettes (DS) made from clayey raw materials collected in the vicinity of Kastrouli, were fired under temperatures (900 and 1050 °C) in oxidizing conditions for comparison with the ancient ceramics. The petrographic analysis performed on thin sections prepared from the sherds has permitted the identification of six main fabric groups and a couple of loners. The aplastic inclusions recognized in all fabric groups but one confirmed the local provenance since they are related to the local geology. Fresh fractures of representative sherds were further examined under a scanning electron microscope (SEM/EDS) helping us to classify them into calcareous (CaO > 6%) and non-calcareous (CaO < 6%) samples (low and high calcium was noted in earlier pXRF data). Here, the ceramic sherds with broad calcium separation are explored on a one-to-one comparison on the basis of detailed mineralogical microstructure. Moreover, their microstructure was studied, aiming to estimate their vitrification stage. The mineralogy of all studied samples was determined by means of X-ray powder diffraction (XRPD), permitting us to test the validity of the firing temperatures revealed by the SEM analysis. The results obtained through the various analytical techniques employed are jointly assessed in order to reveal potters’ technological choices.

Engineering properties of dredged sediments as a raw resource for fired bricks

In the last decades, the amount of dredged sediments (DS) increased in France harbours. Dredged sediments consist of fine soil collected from the deepening, broadening and maintaining of public waterways. The present study reports the investigation of the beneficial reuse of dredged sediments collected from Le Havre (France) harbour as fired material for sustainability requirements. The main challenge is the use of untreated dredged sediments from land deposit of the Seine estuary and port areas as building material, especially for fired bricks manufacture. The chemical, mineralogical and particle size compositions of the raw material were assessed using X-ray fluorescence (XRF), X-ray diffraction (XRD) and laser particle sizer, respectively. The results indicate that the main oxide components are SiO2 and CaO3, while quartz and calcite are the main mineral phases. Lesser amounts of feldspar, chlorite, kaolinite, muscovite and halite were also determined. The physical properties of the raw clay material, including plasticity, organic content and salinity, were investigated in order to assess the product suitability as building material. Ceramic properties such as linear shrinkage, water absorption, bending strength and mineral neo-formations were also investigated in fired bricks at temperatures ranging from 700 to 1000 °C. A high mechanical strength has been obtained at a temperature of 900 °C. The use of ternary diagrams indicates that the raw material falls inside the industrial domain, and ceramic tests show that the raw material could be used in brick making because of its firing behaviour and mechanical resistance. As regards environment sustainability, chemical analysis reveals that the levels of metal traces from leaching tests remain low and within regulatory limits.

Microstructure and Mineralogy of Compressed Earth Bricks Incorporating Shea Butter Wastes Stabilized with Cement

The current context of sustainable development encourages the development of materials with low environmental impact, which explains the renewed interest in earthen constructions. This study is therefore a contribution to the valorization of clay raw materials from Côte d'Ivoire and agro-industrial waste in eco-construction. The aims of this study was studied the effect of shea butter wastes on the mineralogy and microstructure of Compressed Earth Bricks (CEB) stabilized with cement. To do this, two clay raw materials denoted F (Fronan) and K (Katiola) were sampled and then characterized. Various geotechnical and physicochemical tests have shown that these soils are loamy sand of class A2 and essentially contain quartz, kaolinite, mica and ferric compounds. As for shea butter wastes, it is mainly rich in lignin (32%); cellulose (28%) and hemicellulose (19%). Several samples of bricks with different percentages by mass of clay and shea butter wastes (0-10%), stabilized with 5% cement were prepared and then characterized. The results of the mechanical tests showed that the clay-cement matrix could contain 4% shea butter wastes for the formulations with clay F against 6% with clay K. The corresponding optimal formulations are F₉₁TK₄C₅ and K₈₉TK₆C₅ with clays F and K respectively. The SEM images showed a less dense microstructure for the optimal formulation F₉₁TK₄C₅ compared to that of the clay-cement matrix unlike K₈₉TK₆C₅ where the microstructure remained always dense. X-ray diffraction did not allow to observe mineralogical modifications with the incorporation of shea butter wastes into the clay-cement matrix due to their low quantities in the optimal formulations.

Structural and Phase Characteristics of Lightweight Refractories Based on Kaolin and Dry Clays

Strong lightweight refractory materials were obtained with an apparent density ranging from 1060 to 1280 kg/m3 based on clay and nonplastic aluminosilicate raw materials with the introduction of a low-temperature burn-out additive of expanded polystyrene (EPS). The average pore size of the ceramics is 0.05 – 0.35 mm. The optimal fractional composition of the charge and the content of EPS were determined. Physical and technical properties of these ceramic samples fired at 1300 – 1350°C were studied.

КЕРАМИЧЕСКИЙ КИРПИЧ НА ОСНОВЕ НИЗКОКАЧЕСТВЕННОГО ГЛИНИСТОГО СЫРЬЯ С ДОБАВКОЙ ОТХОДОВ ФЕРРОСИЛИКОМАРГАНЦА

The high cost of ceramic pigments contributes to the expansion of research on their replacement with large-tonnage industrial waste. Charge compositions based on low-quality clay raw materials with additions of wollastonite with a dispersion of 10 microns (OOO Tekhnokhim, Novosibirsk) and waste of ferrosilicomanganese deposited in bag filters (West Siberian electrometallurgical plant, Novokuznetsk) were tested. It was found that the introduction of 9 wt. % wollastonite and 5 wt. % waste in semi-dry pressing leads to a content of 15 wt. % wollastonite - 2M with a maximum specimen strength of 45.5 MPa and water absorption of 14 wt. %. Refusal to use the addition of wollastonite with an increase in the dosage of the waste to 10 wt. % made it possible to reduce water absorption to 11.5 wt.% without loss of strength. The color of the che-turnip is dark chocolate.

Recycling of industrial waste as additives for modification of low-plastic clay raw materials

Recycling of industrial waste as additives for modification of low-plastic clay raw materials

Mineralogical, Geochemical and Physico-Chemical Characterization of Clay Raw Materials from Three Clay Deposits in Northern Cameroon

The characterization of clay raw materials of three clay deposits from Northern Cameroon was investigated. The three deposits, located in Gaschiga, Sekandé and Boulgou, are locally used as building materials, but no data are available on these materials and they are relatively unknown. Mineralogical, geochemical and physico-chemical characteristics were studied, using X-ray diffraction, X-ray fluorescence and physico-chemical analyses. Mineralogically, quartz was the most abundant mineral in the studied raw materials. It is associated to abundant quantity of smectite, kaolinite and K-feldspars, and slightly abundant to traces of hematite and amphibole. Geochemically, those clayey soils are more siliceous (SiO2, 51% - 59%) with significant amount of aluminum (Al2O3, 15% - 19%) followed by iron oxides (Fe2O3, 3% - 10%). Other oxides (K2O, MgO, TiO2, Na2O, MnO, CaO and P2O5) are in relatively lower proportion. High level of silica content explains the sandy nature of these clays. The results of granulometric analysis show that the studied raw material contain sand (39% - 68%) as major grain size followed by clay particles (17% - 38%), silt (1% - 36%) and gravels (0% - 16%). The studied clayey soils were moderately plastic, with plasticity index values ranging from 13% to 30%, and are also characterized by very high liquidity limits of 34% - 63%.

Improving sintering by lowering the temperature of melt formation during firing

Liquid sintering for ceramic products is the main process providing necessary properties: strength characteristics, density and porosity. In order to reduce energy consumption for the production of ceramic products it is important to obtain a melt at a lower temperature with a wide sintering interval. Clay raw materials natural composition provides the melt formation at the temperatures above 710° C. The fusible silicate triple eutectics composition, providing the melt formation at the temperatures below 500°C is found. The components for complex fusion additive have been determined. The influence of the amount of complex fusion additive on the dynamics of melt charge change on the basis of Locosovo loam was studied. It was found out that the refractory additive in the amount of 6 to 18.5% extends the sintering interval, reduces the temperature of formation of the refractory melt and provides a decrease in firing temperature by 100°C. The optimum quantity of complex fusible additive providing improvement of sintering of ceramic materials at the expense of decrease in temperature of melt formation during firing is revealed.

USE OF TECHOGENIC RAW MATERIALS IN THE TECHNOLOGY OF CERAMIC BRICKS PRODUCTION

The article presents the results of a study of burnt rocks of mine dumps, ash and slag waste and clay raw materials for the purpose of their use in the technology of manufacturing ceramic bricks. Indicators of their quality are given. In terms of properties and composition, this raw material is close to clay. Compositions and technological modes for the manufacture of ceramic bricks using burnt rocks of mine dumps and ash and slag waste have been developed. The results of laboratory research and industrial tests are presented. The possibility of using this technogenic raw material in the technology of manufacturing ceramic bricks has been proven. The use of burnt rocks and ash and slag waste in the compositions for the manufacture of ceramic bricks can improve its quality, including strength and frost resistance. In all respects, prototypes of ceramic bricks meet the requirements of regulatory documents. The involvement of technogenic raw materials in production allows you to save part of natural raw materials, reduce the cost of products while improving their quality, and help reduce the negative impact of waste on the environment in the areas of their location.The involvement of technogenic raw materials in production allows you to save part of natural raw materials, reduce the cost of products while improving their quality, and help reduce the negative impact of waste on the environment in the areas where they are located.

The development of indonesian local clay as a lightweight expanded clay aggregate (LECA) for organic growing medium

Lightweight Expanded Clay Aggregate (LECA), a clay-based lightweight aggregate expanding after burning at high temperatures, is among the promising material since it can be used as construction materials for buildings and roads, geotechnical fillings, hydroponic growing medium, humidity control, wall damper, heat insulation, water treatment, and others. However, the potential of clay from various places in Indonesia used for LECA as an organic planting medium is still not explored considerably. In this paper, various local clays in Indonesia were studied to obtain a suitable clay as the single raw material for LECA production. Clay raw materials were originated from Purwakarta, Sukabumi, Klaten and Boyolali. The preliminary selection was evaluated based on XRD and XRF test results. The XRD and XRF analysis showed that Boyolali shale and Boyolali bentonite were the most fitted clay as single raw material for LECA production. Both materials were synthesized into LECA through a firing process at 1100°C and 1200°C. Furthermore, the LECA product was characterized by its bloating coefficient and water absorption. The best results were obtained by Boyolali bentonite with a bloating coefficient of 4.63 or can be referred to as medium type and 14.63% for water absorption.

Moving towards resource efficiency and circular economy in the brick manufacturing sector in Zimbabwe

The life cycle assessment of the ABC (Pvt) Ltd brick manufacturing plant has considered land use, fossil resource scarcity, water consumption, global warming and fine particulate matter formation as the impact categories for assessment, with clay mining and coal as the input flows with the highest significant contributions to environmental load. The phase of clay mining (65.8%) is significantly impacting on all the investigated impact categories followed by brick moulding (24.8%) and brick roasting (9.4%) phases, respectively. Hotspots were assessed to identify potential for resource efficiency and circular economy at ABC bricks, Zimbabwe. It can be concluded that ABC is severely polluting the air with emissions above the Environmental Management Agency (EMA) standards for SO2, CO, PM and NOx thus putting kiln workers at risk of respiratory diseases. The calculated Air Quality Index (AQI) ranks CO as the most affecting pollutant with an average score of ∼600. Clay production efficiency was also determined, and an analysis revealed that extrusion and clamping stage contributed highly to the clay losses during brick moulding. Therefore, focus must be placed on these process steps to reduce raw material losses. Furthermore, an environmental waste (fly ash) was used in different weight percentage ratios of 10%, 20% and 100% to substitute clay. The increase of the fly ash content in the brick making process proved to significantly reduce the environmental load among the selected impact categories. ABC uses clay as its main raw material hence the high demand for clay. Strategies should include accounting of used clay daily and raw materials substitution. If ABC uses fly ash from its brick kilns and from other thermal power plant boilers to mix with clay in brick production, then the quantity of clay demanded will be reduced. Using fly ash will reduce rate of clay extraction while at the same time solving the problem of fly ash disposal in Zimbabwe. This circular option will ultimately result in reduced pit expansion, hence reducing top-soil loss and environmental degradation. It should not be disregarded that top-soil loss in turn affects food security. By adopting appropriate technologies, implementing resource efficiency, and designing circular economy patterns, the brick manufacturing sector in Zimbabwe may not only reduce production waste but also comply with enforced environmental protection legislation.

ВЛИЯНИЕ ГРУБОДИСПЕРСНЫХ КОМПОНЕНТОВ НА СВОЙСТВА КЕРАМИЧЕСКОГО МАТЕРИАЛА

In modern conditions, clay raw materials of fine-grained structure are used for the production of building ceramics. The task of using coarse non-traditional non-plastic components in the compositions of ceramic masses and the choice of rational sizes of their grains is relevant. The exclusion of pre-grinding determines the reduction of energy costs and, as a result, the cost of finished products. The paper offers an optiom of using diopside concentrate of various grain sizes in compositions with minor additions of clay and sodium silicate solution. The problems of stress development at the interface of grain and ligament contact, which in case of a negative outcome do not make it possible to obtain a strong structure of a ceramic shard, are solved. The presence of an insignificant voltage formed as a result of the relationship between the diopside and the forming glass phase is revealed, this does not prevent the consideration of the probability of obtaining a ceramic material. The study of the behavior of ceramic samples containing diopside of different granulometric composition when adding a solution of sodium-silicate glass after molding and firing shows the effectiveness of using diopside concentrate in 100-150 microns. Contacts of this size of diopside are wrapped in liquid glass during molding. A glass phase is formed when fired. In this case, the diopside is partially melted, but it is preserved and exists as an independent unit. A smaller grain size during sintering requires more glass phase, which leads to structural stresses, and with a larger size, not enough glass phase is formed and the strength of the material is significantly reduced. When studying the influence of grain size on the properties of the sample, the results of water absorption indicators of 7 %, mechanical compressive strength – 36 MPa, bending strength-17 MPa are obtained. It is found that the dispersion of diopside in 100–150 microns allows to develop a technology for the use of coarse-grained raw materials in the ceramic mass

ИССЛЕДОВАНИЕ СТРУКТУРЫ ГЛИНИСТОГО СЫРЬЯ ДЛЯ КЕРАМИЧЕСКИХ ИЗДЕЛИЙ

the research uses some methods for determining materials, strictly applying the current standards and requirements of the Russian Federation. The degree of scientific development of this research is that specialists of the Department of Engineering Physics and Materials Physics of Engineering Faculty of Bashkir State University and the laboratory of JSC "Ceramics" of the Republic of Bashkortostan conducted research in the field of ceramic materials science for construction purposes. The methodological basis of the research is based on well-known methods of studying the structure of clay raw materials suitable for the production of construction products, with the choice of a stable light range of products and eliminates cracking in the technological process of brick production. The correct composition leads to a reduction in energy consumption without compromising the physical and mechanical characteristics of products.