scholarly journals Effects of Mechanical Activation on Physical and Chemical Characteristics of Coal-Gasification Slag

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 902
Author(s):  
Feng Wu ◽  
Hui Li ◽  
Kang Yang
Keyword(s):  
Specific Surface ◽  
Mechanical Activation ◽  
Surface Area ◽  
Specific Surface Area ◽  
Coal Gasification ◽  
Degree Of Crystallinity ◽  
Chemical Characteristics ◽  
Physical And Chemical Characteristics ◽  
Physical And Chemical ◽  
Coal Gasification Slag

Coal-gasification slag (CGS) was subjected to mechanical grinding by three different methods. We studied the effects of mechanical activation on various physical and chemical characteristics of the CGS, including particle-size distribution, specific surface area, mineral composition, degree of crystallinity, particle morphology, chemical bonding, surface activity and binding energy, anionic-polymerization degree and hydration properties. The results show that there are different effects on CGS characteristics depending on the type of activation applied. Mechanical activation also can increase the specific surface area and the dissolution rates of activated SiO2 and Al2O3, and the major elements (O, Si, Al, Ca) in CGS, whereas the degree of crystallinity and of polymerization of [SiO4] and [AlO6] are reduced by mechanical activation. We also found that the effects of different mechanical-activation methods on the compressive strength and activity were similar and could accelerate the hydration process.

scholarly journals Influence of the Calcination Temperature on the properties of The Alumina as Catalyst Support for Catalysis

Paliva ◽  
2020 ◽  
pp. 155-161
Author(s):  
Tomáš Hlinčík ◽  
Veronika Šnajdrová ◽  
Veronika Kyselová
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Calcination Temperature ◽  
Specific Surface Area ◽  
Catalyst Support ◽  
Chemical Properties ◽  
Total Pore Volume ◽  
Temperature Range ◽  
Calcination Temperatures ◽  
Physical And Chemical

Alumina is commonly used in industrial practice as a catalyst support and it is made from boehmite. Depending on the calcination temperature, this mineral is transformed into various crystalline modifications which have different physical and chemical properties. For this reason, the following parameters were determined at different calcination temperatures: length, width, material hardness, specific surface area and total pore volume. The results show that with increasing calcination temperature there have been significant changes which may be important when using the material as a catalyst support, e.g. in the preparation of catalysts or in the design of cat-alytic reactors. The specific surface area, which decreases in the temperature range 450–800 °C, is an important parameter for the preparation of catalysts, so it is appropriate to choose a temperature of 600 °C, when the specific surface area is above 200 m2·g-1. The effect of calcination temperature on the structural transitions of boehmite was also monitored. The results showed that γ-Al2O3 has the most suitable properties as a catalyst sup-port in the temperature range 450–800 °C.

Some Physical, Chemical and Mineralogical Properties of Some Canadian Fly Ashes

1986 ◽  
Vol 86 ◽  
Author(s):  
R. C. Joshi ◽  
B. K. Marsh
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Chemical Properties ◽  
Water Soluble ◽  
Pozzolanic Activity ◽  
Unburned Carbon ◽  
Magnetic Fraction ◽  
Fly Ashes ◽  
Physical And Chemical

ABSTRACTThis paper gives physical and chemical properties of some Canadian fly ashes. Specific surface area, magnetic fraction, water soluble fraction and fraction finer than 45 μm were determined as part of the physical tests. Thermo-gravimetric analyses (TGA) in oxygen and nitrogen were conducted on raw ash samples. The change of pH with time in suspensions of the different ashes in water was also determined. Pozzolanic activity of the ashes with lime for all the ashes was evaluated to measure ash reactivity.The ash activity seems to be related to fineness of the ash measured by the Blaine air permeability method, but not to the fineness measured by nitrogen sorption. Generally the greater the specific surface area, the higher the reactivity of the ash. The correlation was, however, not strong and no other physical or chemical parameter measured in this investigation seems to be related to pozzolanic activity.The results of pH and TGA tests indicated that the ashes differ in many respects from each other. The TGA data suggest that loss on-ignition in many of the ashes is not entirely due to the presence of unburned carbon. Specific surface area determined by various methods seems to provide different values. No characterization parameter was found that was uniquely related to coal type.

scholarly journals Measuring specific surface area of snow by near-infrared photography

2006 ◽  
Vol 52 (179) ◽  
pp. 558-564 ◽  
Author(s):  
Margret Matzl ◽  
Martin Schneebeli
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Near Infrared ◽  
Two Dimensions ◽  
Chemical Models ◽  
Snow Stratigraphy ◽  
Physical And Chemical

AbstractThe specific surface area (SSA) is considered an essential microstructural parameter for the characterization of snow. Photography in the near-infrared (NIR) spectrum is sensitive to the SSA. We calculated the snow reflectance from calibrated NIR images of snow-pit walls and measured the SSA of samples obtained at the same locations. This new method is used to map the snow stratigraphy. The correlation between reflectance and SSA was found to be 90%. Calibrated NIR photography allows quantitative determination of SSA and its spatial variation in a snow profile in two dimensions within an uncertainty of 15%. In an image covering 0.5–1.0 m2, even layers of 1mm thickness can be documented and measured. Spatial maps of SSA are an important tool in initializing and validating physical and chemical models of the snowpack.

scholarly journals Characterization of Samarium Doped Ceria Powders Having High Specific Surface Area Synthesized by Carbon-Assisted Spray Pyrolysis

2011 ◽  
Vol 485 ◽  
pp. 137-140 ◽  
Author(s):  
Kenichi Myoujin ◽  
Hiroki Ichiboshi ◽  
Takayuki Kodera ◽  
Takashi Ogihara
Keyword(s):  
Specific Surface ◽  
Relative Density ◽  
Spray Pyrolysis ◽  
Surface Area ◽  
Specific Surface Area ◽  
Carbon Sources ◽  
Chemical Properties ◽  
High Specific Surface Area ◽  
Doped Ceria ◽  
Physical And Chemical

Spherical samarium doped ceria (Ce0.8Sm0.2O1.9, SDC) powders having high specific surface area (SSA) were successfully synthesized by carbon-assisted spray pyrolysis (CASP). Saccharides, such as monosaccharides and disaccharides, or organic acids were used as carbon sources. The physical and chemical properties of these powders were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Thermo gravimetry-Differential Thermal Analysis (TG-DTA), and BET. Decarbonized powders obtained by this method exhibit spherical morphologies and nano- and submicron-sizes. The SSA of SDC obtained from CASP was more than seven times higher than that obtained from conventional spray pyrolysis (CSP). The SSA of the decarbonized SDC powders obtained by calcination at 900 °C was estimated to be approximately 70 m2/g by using the BET method. The relative density of SDC obtained from CASP was higher than that obtained from CSP. The relative density of the SDC pellet was highest (96 %) when it was sintered at 1400 °C.

scholarly journals Study of the effect of Mg (II) addition and the annealing conditions on the structure of mesoporous aluminum oxide using Plackett-Burman design

2015 ◽  
Vol 80 (12) ◽  
pp. 1529-1540 ◽  
Author(s):  
Tatjana Novakovic ◽  
Ljiljana Rozic ◽  
Srdjan Petrovic ◽  
Zorica Vukovic ◽  
Miodrag Mitric
Keyword(s):  
Specific Surface ◽  
Crystallite Size ◽  
Heating Rate ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Magnesium Nitrate ◽  
Degree Of Crystallinity ◽  
Burman Design ◽  
Plackett Burman Design

A statistical design was used to investigate the effect of various processing conditions on the structure of sol-gel derived Mg(II) doped alumina. Six processing variables were selected based on the Plackett-Burman design: concentration of magnesium nitrate, time and temperature of alcohol evaporation, temperature and time of annealing and heating rate were changed at two levels. For every set of conditions, samples with different specific surface area and degree of crystallinity were obtained. Analysis of the results showed that annealing temperature , heating rate and concentration of magnesium nitrate were the main factors affecting average crystallite size of the predominant phase of alumina. In the case of the specific surface area, two of selected six variables had pronounced effect; however the temperature of annealing was more effective than others. The present results show that the proposed model that uses crystallite size as a response variables is preferable to further research.

scholarly journals Investigation of the Physical and Chemical Characteristics of the Zeolites of the Kholinsky Deposit

2021 ◽  
Vol 10 (4) ◽  
pp. 65-71
Author(s):  
A. V. Bondarev ◽  
E. T. Zhilyakova ◽  
N. B. Demina ◽  
K. K. Razmakhnin
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Raw Materials ◽  
Molecular Model ◽  
Three Dimensional ◽  
Chemical Characteristics ◽  
Structural Level ◽  
Mineral Raw Materials ◽  
Physical And Chemical ◽  
Sorption Characteristics

Introduction. The mineral resource base of Russia has effective sorption substances that meet pharmaceutical requirements. Promising mineral raw materials are Zeolites, which combine the properties of an adsorbent and a "molecular sieve" due to the porous structure. In addition to the enterosorption direction, natural Zeolites are a source of macro-and microelements, which determines their use as biologically active food additives.Aim. Study of the physical and chemical characteristics of the Zeolites of the Kholinsky deposit.Materials and methods. The zeolite mineral raw materials of the Kholinsky deposit were used as objects of research. Optical microscopy was performed using a Leica DM direct microscope (Microsystems, Germany). Energy dispersion analysis was performed using an electron scanning microscope JSM-5300 (Jeol Ltd, Japan). The sorption characteristics were studied using the ASAP 2400 device (Micromeritics, USA) according to the method. The construction of a virtual three-dimensional molecular model of the Zeolite was carried out using the program Java Applet Jmol.Results and discussion. The physicochemical properties of Zeolites are investigated. It is established that morphologically the particles of the zeolite phase have a size of 5-30 microns, they are evenly distributed over the entire area of the site and represent the first structural level. Particles of the zeolite phase with a size of 5-6 microns form the second structural level due to Clinoptilolite crystals, microcracks and microgeodes. Based on the energy-dispersion spectral analysis, an increased content of the elements K, Na was revealed, which indicates the alkaline composition of the cation exchange complex. The studied Zeolite samples have micropores (volume 0.0031 cm3/g), mesopores (volume 0.0675 cm3/g), and a specific surface area of 29.1840 m2/g. A virtual three-dimensional molecular model of the Zeolite of the Kholinsky deposit has been developed. According to the molecular model, the sorption characteristics of the Kholinsky deposit Zeolite were: specific surface area - 1096.31 m2/g (1916.34 m2/cm3), the average diameter of the spherical molecule for adsorption in the pores is 5.97 A.Conclusion. The analysis of the sorption characteristics of the Zeolite revealed the following features: the pores occupy half the volume of the entire Zeolite, which are available for the sorption of water and low-molecular substances. Each pore in three mutually perpendicular directions communicates with the neighboring ones through "windows". A system of intracrystalline pores and cavities is formed, in which the occlusion and adsorption of molecules of the appropriate size easily occurs.

Influence and Mechanism Analysis of Particle Size Distribution of Multi-System Mineral Admixture on Concrete Performance

2021 ◽  
Vol 1036 ◽  
pp. 386-394
Author(s):  
Fu Xing Cheng ◽  
Yong Liu ◽  
Ji Xiao ◽  
Xiao Xu Deng ◽  
Hai Long Wang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Specific Surface ◽  
Mechanical Activation ◽  
Size Distribution ◽  
Surface Area ◽  
Specific Surface Area ◽  
Mineral Admixture ◽  
Mechanism Analysis

To explore the effect of mechanical activation on the particle size distribution of the composite admixture a self-designed test jet mill is used. We have studied the effects of different specific surface areas of composite admixtures on the workability, mechanical properties and durability of concrete and combined X-ray diffraction (XRD) with scanning electron microscopy (SEM) to analyze the mechanism of concrete performance improvement. Results showed that, mechanical activation can significantly increase the content of particles below 3 um; appropriate increase in the specific surface area of composite admixture is conducive to improving the performance of concrete; As the specific surface area increases, the hydration activity of the composite admixture increases first and then tends to be stable; during the hydration process, more thin-plate Ca(OH)2 is converted into needle-shaped AFt, which improves the cement-based material and thereby improving the macro mechanical properties and durability.

Properties of Mechanical Activation Combustion Synthesied High α-Content Silicon Nitride Powders and Sintered Bulk Ceramics after Iteration Reactions

2008 ◽  
Vol 368-372 ◽  
pp. 862-864 ◽  
Author(s):  
Ke Gang Ren ◽  
Ke Xin Chen ◽  
He Ping Zhou ◽  
Hai Bo Jin ◽  
Ji Dong Zhong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Nitride ◽  
Specific Surface ◽  
Mechanical Activation ◽  
Relative Density ◽  
Combustion Synthesis ◽  
Surface Area ◽  
Specific Surface Area ◽  
A Value

Effect of iteration times on mechanically-activated combustion synthesis of high α-content Si3N4 powders was investigated. Properties of the as-synthesized powders such as α-content (Cα) as well as specific surface area (As) were examined. Results showed that both of Cα and As became higher after iteration reactions. The mechanical properties of the sintered bulk ceramics from as-synthesized powders were also tested to reveal the sinterability of the powders. Results showed that relative density of all the sintered bulk ceramics were higher than 97%. Furthermore, fracture toughness had a trend of becoming higher, which reached a value of 10.2 MPam0.5. Correspondingly, bending strenth became a bit lower.

scholarly journals Mechanical Activation of Granulated Copper Slag and Its Influence on Hydration Heat and Compressive Strength of Blended Cement

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 772 ◽  
Author(s):  
Yan Feng ◽  
Jakob Kero ◽  
Qixing Yang ◽  
Qiusong Chen ◽  
Fredrik Engström ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Specific Surface ◽  
Mechanical Activation ◽  
Surface Area ◽  
Specific Surface Area ◽  
Milling Time ◽  
Copper Slag ◽  
Pozzolanic Activity ◽  
Hydration Heat ◽  
Strength Development

Mechanical activation of granulated copper slag (GCS) is carried out in the present study for the purposes of enhancing pozzolanic activity for the GCS. A vibration mill mills the GCS for 1, 2, and 3 h to produce samples with specific surface area of 0.67, 1.03 and 1.37 m2/g, respectively. The samples are used to replace 30% cement (PC) to get 3 PC-GCS binders. The hydration heat and compressive strength are measured for the binders and derivative thermogravimetric /thermogravimetric analysis (DTG/TGA), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) are used to characterize the paste samples. It is shown that cumulative heat and compressive strength at different ages of hydration and curing, respectively, are higher for the binders blending the GCS milled for a longer time. The compressive strength after 90 d of curing for the binder with the longest milling time reaches 35.7 MPa, which is higher than the strength of other binders and close to the strength value of 39.3 MPa obtained by the PC pastes. The percentage of fixed lime by the binder pastes at 28 days is correlated with the degree of pozzolanic reaction and strength development. The percentage is higher for the binder blending the GCS with longer milling time and higher specific surface area. The pastes with binders blending the GCS of specific surface area of 0.67 and 1.37 m2/g fix lime of 15.20 and 21.15%, respectively. These results together with results from X-ray diffraction (XRD), FTIR, and SEM investigations demonstrate that the mechanical activation via vibratory milling is an effective method to enhance the pozzolanic activity and the extent for cement substitution by the GCS as a suitable supplementary cementitious material (SCM).

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