Low Firing Temperature Research Articles

Aspects of White Cement Production

The results of research aimed at the development of chemical technology for the production of white cement under the conditions of resource conservation and energy saving according to the program of sustainable development are given. Based on computer calculations using the created program “RomanCem”, the quantitative ratios of carbonate, aluminum and silica-containing components of the raw material mixtures for the production of white low-temperature firing cement (≤ 1200 °С) and Eco-cement were determined As a result of the study of 3-component systems based on chalk with aluminum hydroxide, dust quartz and microtalc, new compositions of starting mixtures were developed with a decrease in the content of carbonates and, accordingly, emissions of CO2 into the atmosphere, with a minimization of the content of colored oxides and a corresponding increase in the whiteness of cement. Peculiarities of the phase formation of the investigated mixtures during firing in the range of maximum temperatures of 1100-1200 °C and including the synthesis of ockermanite 2CaO•MgO•2SiO2 when using microtalc were revealed.

Твердофазное восстановление оксидов FexOy и MnxOy углеродом в условиях низкотемпературного обжига шихты на основе марганцевых отходов

Based on complex analytical studies, including methods of atomic emission spectrometry with inductively coupled plasma and X-ray phase analysis of intermediate and final products, the material and mineralogical compositions of manganese wastes of the Dzhezdinsky GOK have been studied. It is shown that the low content of iron and manganese in waste determines the need for a preliminary operation for their enrichment. The mechanism of be havior of iron and manganese oxides under conditions of low-temperature firing of a charge composed on the basis of manganese waste has been studied. Based on thermodynamic calculations of reactions of reduction of iron and manganese oxides by carbon, the possibility of complete reduction of iron to metal from its higher and lower oxides is shown. Higher man ganese oxides are subjected to solid-phase reduction by carbon. Stable manganese oxide at the temperatures of firing to metal is practically not restored due to the positive values of the Gibbs free energy. To increase the iron content in the charge, it is necessary to provide for the addition of iron-containing waste with a high iron content to the charge, for example, rolling scale, etc. When arranging the final charge, it is necessary to take into account the optimal carbon consumption: carbon consumption should not exceed the stoichiometrically necessary amount for the reduction of iron and manganese oxides. The excess carbon not used for the reduction of MnO will remain in the charge, and will be fully used as a reducing reagent during the reduction melting. The metallized product obtained after firing must be subjected to gran ulation in order to obtain durable granular pellets, which will represent the final monoshift for the production of high-quality ferromanganese.

Technology and provenience of the oldest pottery in the northern Pannonian Basin indicates its affiliation to hunter-gatherers

Consensus holds that pottery technology came to Central Europe from the Northern Balkans with independent pottery traditions existing concurrently in Eastern Europe. An unusual grass-tempered pottery dating back to around 5800 cal BC found in lake sediments at Santovka, Slovakia, predated the earliest known Neolithic pottery in the region (~ 5500 cal BC), suggesting unexplored narratives of pottery introduction. Analyses of the pottery’s technology, origin, and grass temper shedding light on ceramic traditions' spread can unveil mobility patterns and community lifestyles. Our findings indicate a non-local provenance, low temperature firing, Festuca sp. grass temper and unique rectangular or cylindrical vessel shapes which align with Eastern European hunter-gatherer practices. Moreover, the pottery style and technology have no analogies in the contemporary Danubian pottery traditions and have more similarities to those of the Eastern traditions. The pottery's raw materials likely originated from distant areas, indicating extensive territorial access for its creators. Our findings imply late Mesolithic hunter-gatherers as the probable artisans and with implications for the site's significance in the late Mesolithic landscape.

Archaeometric analysis of pottery sherds from Barveh Tepe: Insights into Early Bronze Age pottery‐making techniques and firing temperatures

AbstractBarveh Tepe, an archaeological site from the Early Bronze Age in the Zagros Mountains of Iran, was the focus of an archaeometric analysis in this study. The aim was to evaluate the firing temperature of excavated pottery sherds from Barveh Tepe and to gain insights into the pottery‐making techniques employed. A range of analytical methods, including optical microscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) with energy‐dispersive X‐ray spectroscopy (EDS), thermal gravimetric analysis (TGA) and X‐ray diffraction (XRD), was utilized to characterize the pottery sherds. The results revealed the utilization of two primary types of raw clays: calcite‐rich (calcareous) and calcite‐poor (non‐calcareous). The presence of calcite in calcareous pottery samples was confirmed, with the calcareous pottery showing a low CO3−2 vibrational band, indicating a low firing temperature. Through the integration of SEM images, FTIR spectra, TGA curve and XRD pattern results, the estimated firing temperature range for Barveh Tepe pottery was determined to be between 600 and 1100°C. These findings provide new insights into the pottery‐making practices of the Early Bronze Age and shed light on the technological advancements of the period.

Possibilities of retarding the setting of PROMPT natural cement by dosing lignosulfonates

Abstract Roman cement (also Natural cement) is a highly hydraulic binder produced by firing limestone rich in clay minerals. A low firing temperature ranging from 800 °C to 1200 °C is typical for Roman cements. This binder has beneficial functional properties: lower CO2 emissions during production, relatively high strength at a lower bulk density compared to Portland cement, resistance against degradation due to salinity, and better durability. A typical property for this binder is fast setting. This is a problem with the application of natural cement in mortars and concretes, as it significantly shortens their workability time in construction site conditions. The beginning of the setting time of mortars based on PROMPT natural cement can be influenced by retarding additives. Citric acid is currently the most used. Citric acid can negatively affect the properties of hardened mortar and its retarding effect may not be satisfactory. The results of the experimental study are presented in this article, where lignosulfonate-based substances were used as setting retarders. It was investigated that selected types of lignosulfonates are effective as a setting retarder. They have, compared to citric acid, a more pronounced effect of delaying the setting. They also have a significant effect on the strength of the hardened mortar after 28, 56 and 90 days.

ИССЛЕДОВАНИЕ СВОЙСТВ КЕРАМИЧЕСКОГО РЯДОВОГО КИРПИЧА НА ОСНОВЕ ОТХОДОВ БУРЕНИЯ НЕФТЕДОБЫВАЮЩЕЙ ОТРАСЛИ

The purpose of these studies is to determine the possibility of using drill cuttings from the oil fields of the Southern Fed-eral District as a source for the production of ceramic ordinary bricks with their maximum content in the initial mixture to take into account their physical and chemical properties. The objects of study were: drill cuttings from the Slavyanskoye oil field (Krasnodar region) and clay (VKV-2) from of the Vladimirskiy quarry (Rostov region). Based on the research results, a working hypothesis has been formulated, which is that complex processing of the composition of the mineral component of drilling waste and plastic clay at the stages of preparation, molding, and drying ensures, under low-temperature firing conditions, compliance of the physical and chemical properties of brick with the requirements of GOST 530–2018 and their preservation during long-term operation

Thermodynamics of cordierite formation during firing of water-permeable ceramics

The analysis of the influence of an increase in firing temperature on the thermodynamic possibilities of solid-phase chemical reactions in the MgO–Al2O3–SiO2 system in the direction of cordierite formation has been conducted. The thermodynamic direction of solid-phase reactions in the MgO–Al2O3–SiO2 system allows determining rational firing temperatures of materials containing cordierite for the manufacture of products for various purposes. During low-temperature firing (up to 1200 K) of finely dispersed masses based on talc-clay-alumina compositions, materials with high open porosity but low strength characteristics can be obtained. This is because the reactive sintering mainly occurs due to reactions forming intermediates for cordierite synthesis and incomplete processes of destruction in natural mineral raw materials. In the firing temperature range of 1200–1500 K, the thermodynamic probability of reactions immediately via several cordierite formation mechanisms increases, which should limit the growth of individual crystals while increasing their quantity. This should positively affect the strength and heat resistance of materials due to low values of the thermal coefficient of linear expansion. Firing temperatures of 1500–1659 K correspond to the limits for cordierite formation and contribute to the consolidation of the material with a change in the nature of porosity from open to closed. Exceeding firing temperatures above 1659 K results in the thermodynamic instability of the cordierite-corundum phase combination and can lead to the formation of defects due to the appearance of a significant amount of melt in the phase composition of the material.

Enhancing dielectric-silicon interfaces through surface electric fields during firing

Minimising charge losses at silicon interfaces is a major development area for highly efficient solar cells. Here we report on the interface improvements achieved by establishing a surface electric field during low-temperature firing of dielectric thin films. By inducing a corona electric field on the surface of a thin film stack, we observe significant modifications to the silicon-dielectric interface upon annealing, which correlate with the characteristics of interface defects. The passivation properties of the interfaces strongly depend on the polarity and strength of the electric field during firing, as well as the dielectric materials in the layer stack. We show that the surface electric fields not only influence surface carrier population but also affect the resulting chemical interface properties post-annealing. It is postulated that hydrogen migration plays a role in these observed effects. Leveraging the corona-induced electric field enables fine-tuning of both the chemical and field-effect passivation in thin film surface dielectrics, resulting in recombination current densities as low as 2.8 fA cm−2 in research-grade float zone silicon, and 14 fA cm−2 in industrial-grade textured silicon. The simplicity and versatility of the thin film electric polarisation enable a new strategy for controlling and exploiting the chemical enhancement of interfaces in solar cell devices, from current TOPCon and PERC devices to future multijunction silicon-based cells.

Adsorption of Phosphate by Two-Step Synthesis of Ceramsite from Electrolytic Manganese Residue/Dredged Sludge.

Carrying out research on the management of electrolytic manganese residue (EMR) is necessary to maintain the environment and human health. The dredged sludge (DS) and water hyacinth (WH) generated from dredging projects are potential environmental threats, and therefore suitable methods need to be found for their treatment. In this study, ceramsite was prepared by a two-step low-temperature firing method using DS and EMR as raw materials, WH as a pore-forming additive, and aluminate cement as a binder for the adsorption of phosphorus from wastewater. The optimal ratio and process parameters of the ceramsite were determined by mechanical and adsorption properties. The static adsorption experiments were conducted to study the effect of ceramsite dosage and solution pH on the removal of phosphorus. At the same time, dynamic adsorption experiments were designed to consider the influence of flow rate on its actual absorption effect, to explore the actual effect of ceramsite in wastewater treatment, and to derive a dynamic adsorption model that can provide technical support and theoretical guidance for environmental management.

Upcycling municipal solid wastes to self-foaming glass-ceramics by chemical additive-free and rapid low-temperature sintering

Incinerated sewage sludge ash (ISSA) and waste glass (WG) produced in large quantities from municipal solid wastes are either not recycled or are used in relatively low-value applications. Here, we reported a scalable strategy to rapidly convert them, along with waste paper (WP), into novel foamed glass-ceramics (FGCs) by low-temperature sintering, considerably reducing environmental impact and manufacturing cost. The Fe2O3 in ISSA and cellulose in WP were used as precursors to trigger the self-foaming process at low temperatures by carbon-enhanced ferric reduction when WG formed the softened matrix without chemical additives. This study analyzed the foaming mechanism, physical properties of FGCs, and variable importance assisted by thermodynamics and machine learning. The resulting FGCs with 20 wt% ISSA content and 10 wt% WP addition exhibited the excellent properties of a geometric density of 0.76 ± 0.02 g/cm3, volume water absorption of 14.35 ± 2.48%, and compressive strengths of 7.15 ± 0.88 MPa by a short holding (5 min) at a low firing temperature of 850 °C. The successful synthesis and mechanistic study provide new insights into the development of waste-derived high-performance FGCs.

Study of Moulding Sands to Create Three-Layer Magnesium Concrete

Abstract The article is devoted to the problem of creating energy-efficient building materials for enclosing structures. The aim of the research is to develop a recipe and a method for moulding sands placing to create heat-insulating concrete of a multilayer structure. The three-layer magnesium concrete containing layers of different densities is an object of a scientific research. Compositions of moulding sands for concrete’s central and surface layers have been developed and studied. Materials specially developed were used as raw materials for moulding sands; they are as follows: composite magnesial binder and porous filler obtained by low-temperature firing of a granular mixture based on sodium liquid glass and thermal energy waste (fly ash from thermal power plants, aluminosilicate microsphere). Possibility of regulating moulding sand’s properties for concrete’s central layer by varying the content and fractional composition of porous granules has been shown. There has been proposed the moulding sand for surface layers of three-layer magnesium concrete containing crushed porous sand. The related composition of moulding sands favours with adhesion of concrete’s different layers. Various technological methods for producing magnesium concrete of a complex structure have been studied. The research reveals technological and operational characteristics of three-layer magnesium concrete obtained by horizontal and vertical deposition of moulding sands.

Examining the properties, behaviour in firing and potential application of coal mine overburden for stoneware ceramics

Purpose. A binary mixture of a ceramic body was studied, incorporating overburden from a coal mine site in Bontang, East Kalimantan, Indonesia. This overburden material has been tested for the manufacture of stone-ceramic body. Methods. The initial characterization of overburden materials includes testing the chemical composition by XRF analysis and mineral content by XRD analysis on raw materials and overburden exposed to high temperature. The composition of ceramic specimens is a mixture of 85% overburden material and 15% fine sand. Firing temperatures in the range of 900-1100°C were applied to the ceramic body specimen. Then, ceramic properties, such as physical color, plasticity, shrinkage, water absorption and density were analyzed. Findings. The results show that the ceramic specimen experiences densification when exposed to high temperature in this range, which in turn contributes to low water absorption and high flexural strength. This ultimately results in low water absorption below 1.0% at 1100°C, which is favorable for stoneware type of ceramics. The mechanical properties of specimen at 1000°C is in accordance with stoneware body standard. In addition to this, it is believed to be more energy efficient, since the low firing temperature is sufficient to achieve the stoneware specification. Originality. The binary clay-based ceramic have been tested using coal mine overburden and river sand with a high Fe2O3 content. Together with the presence of alkali oxides and calcium in the raw materials, this can potentially reduce the use of fluxing agent. A comprehensive study has been conducted on the characteristics, firing effect and application of stoneware. Practical implications. Some ceramic prototypes from this result were also made using a rotary technique and heated in this temperature range. Since overburden is generally considered to be backfill material, the selective clay material application for ceramics can provide the potential to stimulate local product innovation by utilizing easily available overburden materials.

Low-temperature cordierite ceramics with porous structure for thermal shock resistance products

This article shows the results of the study of low-temperature (1100−1150 °C) porous ceramics of cordierite composition. The technological manufacturing parameters, the features of the microstructural and phase composition of ceramics have been studied. A decrease in the sintering temperature is achieved by appending a part of components using eutectic glass of MgO–Al2O3–SiO2 pseudoternary system. The principle of reactive formation of the structure of the ceramic sample is implemented in the process of its low-temperature firing. The formation of α-cordierite occurs in the process of firing ceramics by means of intensive interaction between eutectic glass components and crystalline fillers, as well as in the result of glass crystallization. By means of the thin layers of the glassy phase, cordierite crystals form a hard base with a branched system of interconnected open pores (30.0−31.3 %). The cordierite-phase crystals, forming the structure of ceramics, have a particle size ranging from 0.2 to 0.3 μm to 1.0−2.0 μm. The specific surface area of the porous cordierite ceramics is in the range of 4.2–4.7 m2/g. The developed cordierite ceramics is characterized by its low coefficient of linear temperature expansion (1.7–2.6)·10−6 °С−1, which determines its high thermal shock resistance (1000−1150°С). The ceramics may be used as filtering elements in high-temperature filtering units, as well as catalyst carriers in the exhaust systems of combustion engines for discharging the sooty component.

Thermodynamic analysis of the reactions of strontium anorthite formation during the firing of thermal shock resistance ceramics based on the eutectic glasses of the SrO–Al2O3–SiO2 systems

Thermal shock resistance ceramic materials must have a high degree of sintering to ensure the required mechanical strength, erosion resistance, and resistance to high-temperature oxidation. However, the search for effective ways to achieve a high degree of sintering of ceramic materials based on the SrO–Al2O3–SiO2 system at low temperatures requires a large amount of experimental research. The aim of this work is to analyze thermodynamically the reactions of strontium-anorthite phase formation at the points of triple eutectics of the SrO–Al2O3–SiO2 system under low-temperature firing conditions. The eutectic points were selected in the region of strontium anorthite crystallization and had a temperature not exceeding 14000C. It has been established that in the case of compliance with the stoichiometric ratio, the final product of the interaction of the components of eutectic glasses S-1 and S-2 with the charging components is the strontium anorthite phase. The most probable is the formation of strontium anorthite in the interaction of eutectic glass components with Al2O32SiO2, which is a product of kaolinite dehydration (Al2O32SiO22H2O). It has been found that the compounds SrOSiO2 and 2SrOAl2O3SiO2 are most active in the interaction with the charging components in the direction of formation of the strontium anorthite phase than SiO2 tridymite. As a result, the sintering of strontium-anorthite compositions at a temperature of 9000C causes a significant increase in the content of the crystalline phase of strontium anorthite. The determined patterns allow making a reasonable choice of glass in the SrO–Al2O3–SiO2 system for the further manufacture of low-temperature strontium-anorthite ceramics.

Light-weighing traditional ceramics by porosity control and consequences on mechanical strength

This work evaluates the impacts of the addition of cellulose fibres (5 and 10 wt%) and pumice powder (5 wt%) as pore forming agents on the porosity, microstructure and mechanical strength of two traditional ceramic compositions: stoneware and terracotta. Open and closed porosities, pore size distribution and morphology were obtained from the combined use of the Archimedes method, mercury intrusion porosimetry and SEM image analyses.The results show an increase in the open porosity ratio in the case of cellulose fibre addition, whereas pumice powder addition promotes an increase in the closed porosity. The addition of cellulose also modifies the pore morphology of stoneware samples and induces a pore size increase. The decrease in mechanical strength caused by a lower firing temperature is greater than the decrease linked to the porosity generated by pore-forming agent addition. As the moduli of rupture of the produced porous tiles are higher than those needed by the standards, this work proposes new opportunities for lightning ceramic products.

Low-temperature firing, temperature-independent, and microwave dielectric performances of ZnNb1.8V0.1O5.75 systems for LTCC applications

The effects of TiO2 doping on the phase transition and microwave dielectric performances of ZnNb1.8V0.1O5.75@xTiO2 (0.05 ≤ x ≤ 0.60) ceramics prepared by conventional mixing methods were investigated. In this study, we report for the first time the phase transition of ZnNb2O6 with columbite structure at low temperature (950 °C) where the τf value is adjusted to near zero. With the increase of TiO2 doping, the following phase transitions are experienced in the ceramics: columbite + monoclinic → columbite + monoclinic + ixiolite → monoclinic + ixiolite → monoclinic + ixiolite + rutile. The microscopic morphology of ceramics is greatly influenced by TiO2 doping. The grain size of ceramics continues to grow as TiO2 doping increases. The microwave dielectric performances of ceramics are intimately connected to the phase transition process, which occurs when the Q×f value constantly declines while the τf value steadily increases and is adjusted to near zero at x = 0.50. After sintering at 950 °C for 6 h, the most optimal microwave dielectric performances were obtained for x = 0.50 with a dielectric constant of 41.18, a Q×f value of 6852 GHz, and a τf value of +6.83 ppm/°C, providing a new option with great potential for microwave devices requiring medium dielectric ceramics.

Production of white cement by low-temperature firing

Production of white cement by low-temperature firing

Reduction of Firing Temperature by Utilization of Secondary Materials for the Synthesis of Forsterite Ceramics

The main aim of this research was to investigate the effect of the addition of coal fly ash as a secondary waste material on the synthesis and properties of forsterite ceramics. The utilization of fly ash as a raw material, which contains flux oxides, reduce the necessary firing temperature for the synthesis of forsterite ceramics in comparison with forsterite ceramics synthetized from high purity or industrial materials, while preserving its refractory properties. The results revealed that forsterite was synthesized as a major crystalline phase in all samples. The optimal firing temperature for obtaining good physico-mechanical parameters was found to be between 1400-1600°C for high purity or industrial materials, while mixtures containing fly ash could achieve similar parameters at lower firing temperatures between 1200-1300°C. The decrease in refractoriness was found to be within acceptable limits for utilization as a refractory material. These findings demonstrate the potential for cost reduction and energy savings through the use of secondary waste materials and reduced firing temperature in the synthesis of forsterite ceramics.

Research on Progress of Forest Fire Monitoring with Satellite Remote Sensing

With satellite remote sensing technology blooming, satellite remote sensing has become a common tool to detect forest fires, and played an important role in forest fire monitoring. This paper sort the research status and progress on satellite remote sensing monitoring for forest fires to provide directions and insights for subsequent research and applications. Through reviewing the literature on satellite remote sensing monitoring for forest fires, we present satellites and sensors for forest fire monitoring, describe forest fire monitoring methods through brightness temperature detection and smoke detection, and summarize current problems of satellite remote sensing monitoring of forest fires. Despite forest fire satellite remote sensing monitoring algorithms are becoming increasingly mature, it is not without problems such as slow migration of cloud detection algorithms, difficulties in unifying spatial and temporal characteristics, and difficulties in detecting small fires and low-temperature fires. Finally, in response to the problems identified, we list some recommendations with a view to providing useful references for future research on forest fire monitoring with satellite remote sensing.

Microwave dielectric properties and chemical bond characteristics of low temperature firing Li3VO4 ceramic with low permittivity

Low-fired Li3VO4 ceramics were fabricated and their sintering characteristics, intrinsic structure of the crystal, and microwave dielectric performances were discussed. After the Rietveld refinements, all samples showed the single orthorhombic Li3VO4 phase with the space group Pnm21 over the sintering temperature 700–820 °C for 2–6 h. The results presented that the permittivity, quality factor, and density exhibited a close correlation at different sintering conditions. The homogenous microstructures and outstanding dielectric performances were achieved upon sintering at 730 °C/4h: εr of 6.65, Q × f value of 15,700 GHz, and τf of −103 ppm/°C. The intrinsic characteristics of Li3VO4 compounds were also discussed by chemical bond theory. The results indicated that the V(1)–O bonds dominated the contribution to the dielectric properties of the Li3VO4 ceramics.