Decomposition of Crystalline Limestones during the Burning Process

2021 ◽  
Vol 325 ◽  
pp. 98-103
Author(s):  
Dorothea Sklenářová ◽  
Karel Dvořák ◽  
Dušan Dolák
Keyword(s):  
Total Porosity ◽  
Point Of View ◽  
Insoluble Residue ◽  
Firing Process ◽  
Burning Process ◽  
Sem Image ◽  
Geological Age ◽  
Crystalline Limestone ◽  
Different Temperatures ◽  
Lime Reactivity

The decomposition of limestone during the firing process is mainly based on the decarbonation of CaCO3. In the case of crystalline limestone, it is the decomposition of calcite crystals. In this study, different limestone properties on the course of decarbonation are studied. Therefore, the samples are determined from a geological and physicochemical point of view (geological age and origin, total porosity, limestone category, chemical analyses and insoluble residue). After thorough identification of the samples, various analyses focused on limestone and lime microstructure are performed, such as SEM image analysis or lime reactivity. For these analyses, the samples are burned at different temperatures. The decrepitation amount of limestones during burning process is determined.

Properties Affecting the Reactivity of Lime

2021 ◽  
Vol 325 ◽  
pp. 92-97
Author(s):  
Dorothea Sklenářová ◽  
Karel Dvořák ◽  
Dušan Dolák
Keyword(s):  
Electron Microscopy ◽  
Total Porosity ◽  
Point Of View ◽  
Insoluble Residue ◽  
Sem Images ◽  
Geological Age ◽  
Different Temperatures ◽  
Identification Parameter ◽  
Lime Reactivity ◽  
Scanning Electron

Lime reactivity is the most used identification parameter for lime quality. The reaction may vary in its rate and maximum reached temperature. In this study, the influence of the properties of limestone on the course of the reaction is studied. The samples are thoroughly examined from a geological point of view (geological age and origin, genesis and diagenesis) and their physicochemical properties are described (total porosity, limestone category, chemical analysis, insoluble residue). Different temperatures and isothermal loads were selected to study the effect of the burning process on the lime microstructure. The newly formed CaO is observed by scanning electron microscopy (SEM images). Lime reactivity analysis is performed, and different reaction courses are compared.

Effect of Limestone Origin on the CaCO3 Decomposition Process and Subsequent Crystallization Process of CaO

2021 ◽  
Vol 321 ◽  
pp. 45-50
Author(s):  
Dorothea Sklenářová ◽  
Karel Dvořák ◽  
Diana Mária Koporcová
Keyword(s):  
High Temperature ◽  
Crystallization Process ◽  
Total Porosity ◽  
Xrd Analysis ◽  
Decomposition Process ◽  
Firing Process ◽  
Geological Age ◽  
Different Temperatures ◽  
Increasing Temperature ◽  
Multiple Samples

In this study, the process of decomposition of CaCO3 and crystallization of CaO has been analyzed. The aim of this work is to compare behavior and changes in microstructure between different limestone samples (as geological age and origin, total porosity, hardness category). Studied samples were analyzed in high temperature chamber during the firing process by XRD analysis. With the increasing temperature, the growth of crystallites was measured and computed. In multiple samples a different behavior in these properties was observed. Further analysis studied different temperatures of the end of decomposition of CaCO3 and the beginning of formation of CaO in soft-porous and hard-recrystallized limestones.

Ion–solvent interaction of tetraalkylammonium ions in solvents of high dielectric constant. Part I. Conductance and Walden product of tetraalkylammonium ions in N-methylacetamide at different temperatures

1968 ◽  
Vol 46 (22) ◽  
pp. 3525-3530 ◽  
Author(s):  
Raj Deo Singh ◽  
Pushti Prakash Rastogi ◽  
Ram Gopal
Keyword(s):  
Dielectric Constant ◽  
Aqueous Solutions ◽  
High Dielectric Constant ◽  
Electrical Conductance ◽  
Point Of View ◽  
Walden Product ◽  
Solvent Interaction ◽  
Tetraalkylammonium Ions ◽  
Different Temperatures ◽  
High Dielectric

Ion–solvent interaction of the tetraalkylammonium ions (R4N+) in N-methylacetamide has been studied from the point of view of electrical conductance and the derived Walden product. The results indicate R4N+ ions to be structure breakers in this solvent, quite opposite to their general behavior in aqueous solutions. The effect is conspicuous in the smaller Me4N+ and Et4N+ ions, but is less marked in the larger ions.

Morphological and chromatographic characterization of molecularly imprinted monolithic columns.

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Jakub Sirc ◽  
Zuzana Bosakova ◽  
Pavel Coufal ◽  
Jiri Michalek ◽  
Martin Pradny ◽  
...  
Keyword(s):  
Pore Radius ◽  
Stationary Phases ◽  
Mercury Porosimetry ◽  
Theoretical Plate ◽  
Total Porosity ◽  
Point Of View ◽  
Monolithic Columns ◽  
Molecularly Imprinted ◽  
Chromatographic Parameters ◽  
Increasing Temperature

AbstractThe chromatographic stationary phases based on molecularly imprinted monoliths were prepared by free radical polymerization and subsequently characterized. The mixture of commonly used comonomers of ethylene dimethacrylate/methacrylic acid was polymerized in presence of various porogenic mixtures. Tosyl-L-phenylalanine was selected as a model template. Polymerization steps were carried out in the glass columns (i.d. of 3.3 mm) enabling UV initiation. Difficulties encountered with polymerization in situ, e.g. volume contraction and adhesion of polymer onto the glass inner wall, were successfully solved. The morphology of monoliths was investigated by electron microscopy, mercury porosimetry and surface area measurements. The influence of polymerization conditions on monolith morphology and subsequent chromatographic properties was evaluated. Polymers prepared by UV polymerization showed higher total porosity and the most frequent pore radius compared to the same polymers prepared thermally. The prepared monoliths by UV irradiation were also significantly more permeable for mobile phase during the chromatography tests. Morphology of monoliths prepared in dodecanol/toluene porogenic mixture markedly depended on the temperature of polymerization; the most frequent pore radius decreased with increasing temperature. From chromatographic point of view, monolithic columns were tested by separations of standard hydrophobic solutes. Height equivalent to a theoretical plate reached the values of approx. 25 μm, Walters indices of hydrophobicity laid slightly above 3. Prepared monoliths were compared to the conventional columns, filled with the particles prepared from the polymer of the same composition and preparation. In many cases the monolithic columns showed better chromatographic parameters.

A Study on the Synthesis of SiC Powder from the Silicon Sludge of the Photovoltaic Industry

2012 ◽  
Vol 724 ◽  
pp. 49-52 ◽  
Author(s):  
Woo Teck Kwon ◽  
Soo Ryong Kim ◽  
Y. Kim ◽  
Yoon Joo Lee ◽  
Eun Jin Jung ◽  
...  
Keyword(s):  
Particle Size ◽  
Solar Cell ◽  
Silicon Powder ◽  
Point Of View ◽  
Economic Point ◽  
Heat Treated ◽  
Particle Size Analyzer ◽  
Different Temperatures ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

β-SiC powder was synthesized directly from silicon sludge with carbon black. Large amount of silicon sludge is generated from Solar Cell industry. In an environmental and economic point of view, recycling silicon sludge is important. In this study, two kinds of silicon sludge were characterized using XRD, SEM/EDS and FT-IR. SiC powder was synthesized by the reaction of ball-milled silicon powder for 3h in vacuum at different temperatures (1350 and 1600). Physical properties of the heat treated SiC have been characterized using a SEM, XRD, Particle size analyzer and FT-IR Spectroscopy.

scholarly journals Thermal behaviour of glacier and laboratory ice

1991 ◽  
Vol 37 (127) ◽  
pp. 401-413 ◽  
Author(s):  
J. F. Nye
Keyword(s):  
Freezing Point ◽  
Impurity Content ◽  
Point Of View ◽  
Heat Diffusion ◽  
Different Temperatures ◽  
Polythermal Glacier ◽  
Ice Water ◽  
Concentration Of Impurities ◽  
Soluble Impurity ◽  
Single Medium

AbstractWater is present in glaciers in the form of veins at the three-grain junctions. This water remains unfrozen even many degrees below the normal freezing point, mainly because it contains much of the soluble impurity content of a glacier, but also because of the microscopic curvature of the ice–water interfaces. As the temperature is lowered and the veins shrink, the concentration of impurities in them increases, and the curvature effect also increases. The predicted relation between vein size and temperature has now been verified by laboratory experiments.Because of the latent heat of the vein water, the ice behaves macroscopically as a continuum with an anomalous specific heat capacity that depends strongly on temperature. From this point of view, a polythermal glacier is a single medium with continuously varying properties, rather than consisting of distinct cold and temperate phases with sharp boundaries between them. The paper sets up differential equations for heat diffusion in such a continuum. To explain the local uniformity of the vein system seen under the microscope, it is found necessary to include the effect of diffusion of solutes along the veins.Solutions are presented for a model in which two semi-infinite slabs, initially having different temperatures, impurity concentrations and vein sizes, are instantaneously brought into contact. In this way, transition thicknesses between cold and temperate ice are estimated, and also the velocities of various kinds of waves that are generated from the original discontinuity at the interface.

scholarly journals Development of Crystallinity of Triclinic Polymorph of Tricalcium Silicate

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3734
Author(s):  
Simona Ravaszová ◽  
Karel Dvořák
Keyword(s):  
Crystallite Size ◽  
Crystallization Process ◽  
Tricalcium Silicate ◽  
Point Of View ◽  
Firing Process ◽  
Cement Production ◽  
X Ray ◽  
Sintering Time ◽  
Wide Range ◽  
Main Components

Tricalcium silicate phase is one of the main components of modern Portland cements. One of the major industrial challenges in the field of cement production is mapping the influence of individual clinker minerals and their polymorphs on the properties of industrially produced clinkers. The primary goal of this work is to improve the fundamental knowledge of understanding the process of alite formation and development from a crystallographic point of view. This study focuses on the observation of the crystallization process of triclinic alite during the firing process, which to date has not been thoroughly described. The effects of a wide range of temperatures and sintering periods on crystallinity were assessed on samples fired in platinum crucibles in a laboratory furnace. X-ray analysis—together with calculation of crystallinity using Scherrer’s equation—was used for observing the crystallite size changes of T1 alite polymorph. According to the acquired results, among the most technologically and economically advantageous regimes of production of a high-quality triclinic alite is the temperature of 1450 °C and sintering time of two hours. The most significant changes in the crystallite size occurred within the first hour of sintering for the whole investigated temperature range.

scholarly journals On Influence of Mechanical Properties of Gun Propellants on Their Ballistic Characteristics Determined in Closed Vessel Tests

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3243
Author(s):  
Radosław Trębiński ◽  
Jacek Janiszewski ◽  
Zbigniew Leciejewski ◽  
Zbigniew Surma ◽  
Kinga Kamińska
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Point Of View ◽  
Closed Vessel ◽  
Shape Functions ◽  
Stress Strain ◽  
Static Compression ◽  
Burning Process ◽  
Double Base ◽  
Gun Propellants

The geometric burning law of gun propellants is widely used in computer codes used for the simulations of the internal ballistics of guns. However, the results of closed vessel tests prove that the burning process of some propellants deviates from the geometric law. Validation of the hypothesis that observed deviations can be attributed to the cracking of propellant grains was the aim of this work. In order to verify the hypothesis, three types of gun propellants were chosen with considerably differing mechanical strengths: a single-base propellant, a double-base propellant, and a composite propellant. The mechanical properties of the gun propellants were tested using a quasi-static compression method with strain rate values of the order of 0.001 s−1 and the Split Hopkinson Pressure Bar technique with the strain rate in the range of 1000–6000 s−1. The mechanical responses of the propellants were assessed on the basis of the true stress–strain curves obtained and from the point of view of the occurrence of cracks in the propellant grains specimens. Moreover, closed vessel tests were performed to determine experimental shape functions for the considered gun propellants. Juxtaposition of the stress‒strain curves with the experimental shape functions proved that the observed deviations from the geometrical burning law can be attributed mainly to the cracking of propellant grains. The results obtained showed that the rheological properties of propellants are important not only from the point of view of logistical issues but also for the properly controlled burning process of propellants during the shot.

scholarly journals Q-Factor Performance of 28 nm-Node High-K Gate Dielectric under DPN Treatment at Different Annealing Temperatures

Electronics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2086
Author(s):  
Chii-Wen Chen ◽  
Shea-Jue Wang ◽  
Wen-Ching Hsieh ◽  
Jian-Ming Chen ◽  
Te Jong ◽  
...  
Keyword(s):  
Figure Of Merit ◽  
Gate Dielectric ◽  
Gate Dielectrics ◽  
Nitrogen Concentration ◽  
Point Of View ◽  
Tunneling Effect ◽  
Q Factor ◽  
High K ◽  
Different Temperatures

Q-factor is a reasonable index to investigate the integrity of circuits or devices in terms of their energy or charge storage capabilities. We use this figure of merit to explore the deposition quality of nano-node high-k gate dielectrics by decoupled-plasma nitridation at different temperatures with a fixed nitrogen concentration. This is very important in radio-frequency applications. From the point of view of the Q-factor, the device treated at a higher annealing temperature clearly demonstrates a better Q-factor value. Another interesting observation is the appearance of two troughs in the Q-VGS characteristics, which are strongly related to either the series parasitic capacitance, the tunneling effect, or both.

Experimental Study on the Compressive Strength and AE Characteristics of High-temperature Treated and LN2 Cooled Sandstone

2021 ◽  
Author(s):  
Rui Ding ◽  
Qiang Sun ◽  
Hailiang Jia ◽  
Liyun Tang ◽  
Delu Li
Keyword(s):  
Compressive Strength ◽  
Temperature Difference ◽  
Room Temperature ◽  
Shear Failure ◽  
Total Porosity ◽  
High Porosity ◽  
Quenching Temperature ◽  
Red Sandstone ◽  
Different Temperatures ◽  
Development And Utilization

Abstract Liquid nitrogen (LN2) fracturing is beneficial to the development and utilization of geothermal energy. In this paper, the red sandstone was heated from room temperature to different temperatures (25°C-800°C) and then cooled with LN2. After attaining the room temperature, NMR, uniaxial compression, and acoustic emission (AE) tests were conducted, and results were compared for different samples. The results showed that with the increase in quenching temperature difference, the volume of micropores decreased gradually, while the volume of fine pores, mesopores, macropores and total porosity increased, resulting in the reduction of the compressive strength. Higher quenching temperature difference also reduced the sample’s total time to fail, and the failure mode was transformed from single inclined shear failure to conical failure. This is because the thermal stress (caused by the rapid cooling of LN2) expanded the original cracks of the sandstone, leading to high porosity and low compressive strength of the heat-treated and quenched samples.

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