Mineralogical Transformations and Microstructure After Disposal of Cementitious Advanced Coaltechnologyby-Product

1994 ◽  
Vol 370 ◽  
Author(s):  
G.J. McCarthy ◽  
R.D. Butler ◽  
D.W. Brekke ◽  
S.D. Adamek ◽  
J.A. Parks ◽  
...  
Keyword(s):  
Crystalline Hydrate ◽  
Hydration Products ◽  
Fluidized Bed Combustion ◽  
X Ray Diffraction ◽  
Natural Conditions ◽  
X Ray ◽  
The Core ◽  
Test Cells ◽  
One Year ◽  
By Products

AbstractBy-products from two advanced coal technologies, Fluidized Bed Combustion (FBC) and Limestone Injection Multistage Burner (LIMB), were found to be cementitious when mixed with water and compacted. However, exposure to natural conditions in test cells resulted in losses of strength and increases in permeability over a period of years. Changes in mineralogy and microstructure with time in recovered core samples have been characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). Up to 80 wt% of the core materials had converted to crystalline hydrate phases by the end of two years. Ettringite, gypsum and portlandite were the initial hydration products. In the LIMB materials, formation of thaumasite in microfractures, channels and voids was detected after one year, and in the FBC material after two years. Thaumasite formation was accompanied by reductions in gypsum and portlandite; it did not appear to be forming at the expense of ettringite. EDS examination of many ettringite and thaumasite crystals showed that the former always contained some Si and the latter some Al, which is evidence for ettringite-thaumasite solid solution. Thaumasite formation accompanied marked losses in strength and increases in permeability.

An Investigation of Fluidized Bed Combustion By-Products from Four Iowa Power Plants

1991 ◽  
Vol 245 ◽  
Author(s):  
Carol L. Kilgour
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Particle Size ◽  
Power Plants ◽  
Size Distributions ◽  
Fluidized Bed Combustion ◽  
X Ray Diffraction ◽  
X Ray ◽  
By Products ◽  
Scanning Electron

ABSTRACTFluidized bed combustion (FBC) residues from four Iowa power plants were characterized to provide background with respect to chemical, physical, mineralogical and microstructural parameters that might affect their utilization potential. Methodologies used include: bulk chemical analysis; grain size analysis; specific gravity determination; mineralogical analysis by x-ray diffraction; scanning electron microscopy; and thermal analysis.Chemical analysis of the major components showed the separation of the constituents during combustion. The bottom ash is derived from the calcined and partly sulfated limestone, thus the concentration of calcium and sulfur compounds is greater. The fly ash however is derived mostly from the coal and therefore exhibits higher concentrations of coal ash components such as silica (SiO2), alumina (Al2O3), and ferric oxide (Fe2O3). The alkalis appear to be more concentrated in the fly ash.The measured particle size distributions of the bulk samples varied greatly, from extremely coarse (mean particle size ˜2000 μm) to fine (mean particle size ˜25 μm). The size distributions also varied in breadth. Specific gravities values recorded ranged from about 2.65 to about 3.05.X-ray diffraction analyses showed that most of the FBC by-products contain, as easily detectable crystalline components, only quartz, anhydrite and lime, and as is to be expected due to the low combustion temperatures, do not show broad peaks characteristic of glass in conventional fly ashes. Scanning electron microscopy revealed the FBC by-products to be extremely intricate mixtures of particles of complex and variable composition and internal structure.FBC by-products are shown to be extremely complex mixtures of particles of variable composition and internal structure. However, despite their local variation, useful results can be obtained by overall chemical and physico-chemical analyses of their composition. The exploitable properties of FBC residue include the somewhat cementitious nature and the granularity. However, their heterogeneous nature, lack of pozzolanic properties, and elevated sulfate content may limit their uses, especially in construction.

THE HYDRATION OF DICALCIUM SILICATE AND TRICALCIUM SILICATE

1936 ◽  
Vol 14b (1) ◽  
pp. 20-30 ◽  
Author(s):  
N. B. Keevil ◽  
T. Thorvaldson
Keyword(s):  
Calcium Hydroxide ◽  
Tricalcium Silicate ◽  
Dicalcium Silicate ◽  
Crystalline Hydrate ◽  
Saturated Steam ◽  
Partial Hydrolysis ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Constant Weight ◽  
X Ray

Samples of β-dicalcium silicate, γ-dicalcium silicate, tricalcium silicate, hillebrandite and dehydrated hillebrandite were exposed to saturated steam at temperatures between 50° and 375 °C. After drying to constant weight (usually over calcium oxide) the increase in weight and the amount of free calcium hydroxide were determined. Microscopic examinations and X-ray diffraction patterns of the products were made. The hydration products were then dehydrated and similar studies of the products made. The hydrolysis of the hydration products also was studied.It was found that between 110° and 350 °C. β- and γ-dicalcium silicates may absorb water without hydrolysis to form three crystalline products. Two of these are identical with products already described (20); the third product appears to possess another characteristic crystalline structure as shown by the X-ray pattern, but to have a variable water content with a limiting composition of 2CaO∙SiO2∙H2O. The hydration product may be dehydrated without the liberation of lime.When conditions favoring hydrolyses are avoided, tricalcium silicate hydrates directly to a crystalline hydrate which probably has the limiting composition, 3CaO∙SiO2∙2H2O, although products holding from 1.3 to 2 moles of water give the same X-ray diffraction pattern. When the conditions favor partial hydrolysis, tricalcium silicate decomposes into calcium hydroxide and crystalline hydrated dicalcium silicate. Dehydration of hydrated tricalcium silicate gives one mole of lime along with dicalcium silicate.Hillebrandite exposed to saturated steam at 160 °C. remained unchanged while a sample of dehydrated hillebrandite on hydration gave a product similar to that obtained from β-dicalcium silicate.When treated with a large excess of water, the hydrated silicates hydrolyze to the same extent as the anhydrous silicates, but the final equilibrium is attained more rapidly, especially in the case of hydrated dicalcium silicate.

scholarly journals Enhancing carbonation and chloride resistance of autoclaved concrete by incorporating nano-CaCO3

2020 ◽  
Vol 9 (1) ◽  
pp. 998-1008
Author(s):  
Guo Li ◽  
Zheng Zhuang ◽  
Yajun Lv ◽  
Kejin Wang ◽  
David Hui
Keyword(s):  
Cement Hydration ◽  
Mercury Intrusion Porosimetry ◽  
Hardened Concrete ◽  
Optimal Dosage ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Carbonation Depth ◽  
X Ray ◽  
Chloride Resistance

AbstractThree nano-CaCO3 (NC) replacement levels of 1, 2, and 3% (by weight of cement) were utilized in autoclaved concrete. The accelerated carbonation depth and Coulomb electric fluxes of the hardened concrete were tested periodically at the ages of 28, 90, 180, and 300 days. In addition, X-ray diffraction, thermogravimetry, and mercury intrusion porosimetry were also performed to study changes in the hydration products of cement and microscopic pore structure of concrete under autoclave curing. Results indicated that a suitable level of NC replacement exerts filling and accelerating effects, promotes the generation of cement hydration products, reduces porosity, and refines the micropores of autoclaved concrete. These effects substantially enhanced the carbonation and chloride resistance of the autoclaved concrete and endowed the material with resistances approaching or exceeding that of standard cured concrete. Among the three NC replacement ratios, the 3% NC replacement was the optimal dosage for improving the long-term carbonation and chloride resistance of concrete.

Decolorization of Coking Wastewater by Mineral Adsorbents

2011 ◽  
Vol 415-417 ◽  
pp. 1675-1678
Author(s):  
Kai Ning Yu ◽  
Cheng Wang ◽  
Yang Yu ◽  
Yan Li
Keyword(s):  
Electron Microscopy ◽  
Coking Wastewater ◽  
Fluidized Bed Combustion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Decolorization Efficiency ◽  
Mineral Adsorbents ◽  
Sequence Rule ◽  
Scanning Electron ◽  
Raw Wastewater

The decolorization of coking wastewater is an urgent issue for coking wastewater treatment. Using mineral adsorbents to deal with the coking wastewater is an effective way to solve the above problem. In this paper, fluidized bed combustion (FBC) ashes, diatomite and clinoptiolite were used to decolorize the coking wastewater. UV-Vis was used to estimate the decolorization efficiency of the FBC ashes. The materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the sequence rule for the decolorization effect of three mineral adsorbents is FBC ashes > diatomite > clinoptiolite. In addition, the chroma of treated coking wastewater reduced from 320 times to less than 5 times in the comparison of raw wastewater. It is much lower than the chroma of GB8978-1996 1A discharge standard. The excellent decolorization effect of FBC ashes might be due to large contains of CaO and f-CaO.

Unprecedented Hexa- and Undecanuclear Frameworks of Two New Tin(IV) Oxo Clusters Resulting from Partial Debenzylation Reactions

2010 ◽  
Vol 65 (11) ◽  
pp. 1293-s1308 ◽  
Author(s):  
Laurent Plasseraud ◽  
Hélène Cattey ◽  
Philippe Richard
Keyword(s):  
Solid State ◽  
1H Nmr Spectroscopy ◽  
Trifluoromethanesulfonic Acid ◽  
Synthetic Route ◽  
State Structure ◽  
X Ray Diffraction ◽  
Neutral Cluster ◽  
Broad Resonance ◽  
X Ray ◽  
The Core

A new and facile synthetic route to the known neutral cluster ((PhCH2)2SnO)6[((PhCH2)2SnOH)2- (CO3)]2 (2) as well as its reactivity toward trifluoromethanesulfonic acid (HO3SCF3, TfOH) are reported. The solid-state structure of the new solvate 2·6C7H8 has been determined by single-crystal X-ray diffraction. The core of 2 can be described as a pair of coplanar pentanuclear [(PhCH2)2SnO]5 ladders bridged at their ends by two carbonate groups. Successive additions of TfOH to a suspension of 2 in CD3CN were monitored by 119Sn{1H} NMR spectroscopy showing the transformation of the fingerprint of 2 (δ = −244, −246, −306 ppm), via new upfield signals, to a final broad resonance located at δ = −474 ppm. Thereafter, two unprecedented ionic monobenzyltin(IV) oxo clusters, 3 and 4, resulting from a debenzylation reaction and exhibiting unusual hexa- and undecanuclear frameworks, respectively, have been isolated as single crystals.

scholarly journals Stabilization Study of a Contaminated Soil with Metal(loid)s Adding Different Low-Grade MgO Degrees

2020 ◽  
Vol 12 (18) ◽  
pp. 7340
Author(s):  
Jessica Giro-Paloma ◽  
Joan Formosa ◽  
Josep M Chimenos
Keyword(s):  
Contaminated Soil ◽  
Contaminated Soils ◽  
Low Grade ◽  
X Ray Diffraction ◽  
Optimal Stabilization ◽  
X Ray ◽  
Neutralization Capacity ◽  
Stabilizing Agents ◽  
Acid Test ◽  
By Products

Low-grade magnesium oxide (LG-MgO) was proposed as ordinary Portland cement (OPC) or lime substitute (CaO) for metal(loid)s remediation in contaminated soils. Some metal(loid)s precipitate at pH ≈ 9 in insoluble hydroxide form thus avoiding their leaching. LG-MgO avoids the re-dissolution of certain metal(loid)s at 9.0 < pH < 11.0 (pH-dependents), whose solubility depends on the pH. A highly contaminated soil with heavy metal(loid)s was stabilized using different LG-MgO by-products sources as stabilizing agents. Two of the three studied LG-MgOs were selected for the stabilization, by mixing 5, 10, and 15 wt.%. The effect of using LG-MgO not only depends on the size of the particles, but also on those impurities that are present in the LG-MgO samples. Particle size distribution, X-ray fluorescence (XRF), X-ray diffraction (XRD), thermogravimetric analysis, citric acid test, specific surface, bulk density, acid neutralization capacity, batch leaching tests (BLTs), and percolation column tests (PCTs) were techniques used to deeply characterize the different LG-MgO and the contaminated and remediated soils. The remediation’s results efficacy indicated that when the medium pH was between 9.0 and 11.0, the concentration of pH-dependent metal(loid)s decreases significantly. Although around 15 wt.% of a stabilizing agent was appropriate for the soil remediation to ensure an alkali reservoir that maintains optimal stabilization conditions for a long period, 5 wt.% of LG-MgO was enough to remedy the contaminated soil. When evaluating a polluted and decontaminated soil, both BLTs and PCTs should be complementary procedures.

Synthesis and Magnetic Properties of CoAl2O4 Coated Co Solid Solution Nanocapsules

2010 ◽  
Vol 663-665 ◽  
pp. 1256-1259
Author(s):  
Gui Mei Shi ◽  
Ge Song ◽  
Shu Lian ◽  
Jin Bing Zhang
Keyword(s):  
Solid Solution ◽  
Photoelectron Spectrum ◽  
Room Temperature ◽  
Ferromagnetic State ◽  
Antiferromagnetic Order ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Core ◽  
New Type ◽  
The Magnetic Field

A new type of antiferromagnetic CoAl2O4 coated ferromagnetic Co solid solution is synthesized by arc-discharging. Typical HRTEM images show that the nanocapsules form in a core-shell structure. The size of the nanocapsules is in range of 10-90 nm and the thickness of the shell is about 3-10 nm. X-ray photoelectron spectrum (XPS) and X-ray diffraction (XRD) reveal that the core consists of Co solid solution, while the shell is CoAl2O4. The magnetic field and temperature dependence of magnetizations confirm that the Co solid solution nanocapsules are basically in the ferromagnetic state below Curie temperature. In addition, the antiferromagnetic order occurs with Neél temperature TN of about 5 K. The saturation magnetization of Ms = 76.1 Am2/kg and the coercive force of Hc= 23.28 kA/m are achieved at room temperature for the Co solid solution nanocapsules.

scholarly journals Sustainable Nanopozzolan Modified Cement: Characterizations and Morphology of Calcium Silicate Hydrate during Hydration

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
N. Mohamed Sutan ◽  
I. Yakub ◽  
M. S. Jaafar ◽  
K. A. Matori ◽  
S. K. Sahari
Keyword(s):  
Cement Paste ◽  
Physical And Mechanical Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pozzolanic Reactivity ◽  
Synthetic Materials ◽  
Water To Cement Ratio ◽  
Mechanical Properties Characterization ◽  
Micro Silica ◽  
By Products

There are environmental and sustainable benefits of partially replacing cement with industrial by-products or synthetic materials in cement based products. Since microstructural behaviours of cement based products are the crucial parameters that govern their sustainability and durability, this study investigates the microstructural comparison between two different types of cement replacements as nanopozzolan modified cement (NPMC) in cement based product by focusing on the evidence of pozzolanic reactivity in corroboration with physical and mechanical properties. Characterization and morphology techniques using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) were carried out to assess the pozzolanic reactivity of cement paste modified with the combination of nano- and micro silica as NPMC in comparison to unmodified cement paste (UCP) of 0.5 water to cement ratio (w/c). Results were then substantiated with compressive strength (CS) results as mechanical property. Results of this study showed clear evidence of pozzolanicity for all samples with varying reactivity with NPMC being the most reactive.

Polymorphs of oxindole as the core structures in bioactive compounds

CrystEngComm ◽  
2018 ◽  
Vol 20 (12) ◽  
pp. 1739-1745 ◽  
Author(s):  
Barbara Hachuła ◽  
Maciej Zubko ◽  
Paweł Zajdel ◽  
Maria Książek ◽  
Joachim Kusz ◽  
...  
Keyword(s):  
Single Crystal ◽  
Bioactive Compounds ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Core

A new polymorph of oxindole (termed as “δ-form”) has been found and characterized by single-crystal X-ray diffraction.

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