Quantitative X-ray Diffraction Techniques Research Articles

Superhydrophilic spinel ceramic membranes for oily emulsion wastewater treatment

It remains critically challenging for highly efficient recycling of hazardous solid state sludges and economic treatment of wastewaters in one protocol. Herein, we proposed a waste-to-resource strategy for rational design of spinel ceramic membranes, simultaneously addressing the issues of copper-bearing waste recycling and oily wastewater treatment. A spinel phase conversion mechanism was proposed based on via qualitative and quantitative X-ray diffraction techniques, indicating that spinel was steadily formed through the reactions between copper oxide and alumina (major) or mullite (minor) at 970–1060 °C. Then, spinning and sintering parameters were systematically studied to rationally tailor membrane structure and properties such as morphology, porosity, pore size, permeability and mechanical strength. With rational structure design, the spinel-based ceramic membranes showed superhydrophilicity and underwater superoleophobicity, enabling enhanced flux with mitigated oil fouling especially for light oils. Even for heavy oils, permeate flux was enhanced with mitigated fouling at alkaline conditions. Efficient separation was achieved for not only synthetic oily emulsion but real wastewater. This study demonstrates the feasibility of recycling hazardous metal-bearing sludges into functional ceramic membranes for water treatment applications, offering a promising sustainable waste-to-resource protocol.

Surface characteristics investigation of tool steel machined by powder metallurgy tool in EDA

Use of sintered tool electrodes for surface alloying by electrical discharge alloying (EDA) process has emerged as an alternating machining option with a view to improve surface properties. The present study identifies the appropriate process parameter settings to machine high carbon tool steel (En31) for higher surface finish using copper-manganese (Cu–Mn) powder metallurgy (PM) tool electrode. The effect of six different process parameters was evaluated using Taguchi’s experimental design and analysis of variance. The characterization of the surface alloyed with Mn and carbon was done by micro-hardness measurement, scanning electron microscope (SEM), atomic force microscope (AFM), energy dispersive x-ray spectrum (EDX) quantitative analysis and x-ray diffraction (XRD) technique. Also, the comparison was done with the surface machined using conventional Cu electrode. The surface machined with Cu-Mn PM tool electrode was found to be significantly alloyed with Mn and carbon having fewer micro-voids and no micro-cracks. Nano-size hillocks and valleys were found on the alloyed surface that is expected to improve the oil retention property of the surface. Presence of phases like Mn5C2 and Fe3C in the alloyed surface resulted in 95% and 33% higher microhardness than the base material and surface machined with conventional Cu electrode, respectively.

Cadmium stabilization via silicates formation: Efficiency, reaction routes and leaching behavior of products

Stabilizing cadmium by incorporating it into crystalline products is an effective approach to detoxify cadmium-containing wastes. In this study, two Si-rich matrices in amorphous and crystalline forms (i.e., silica fume and α-quartz, respectively) were employed to incorporate Cd. The processing parameters, namely the type of Si-rich matrix, Cd/Si molar ratio (Г) and sintering temperature, were thoroughly investigated using quantitative X-ray diffraction technique. Cd incorporation was more energetically favored when silica fume was used rather than when α-quartz was used because of the lower Gibbs free energy of formation for silica fume. The sintering temperature and Г values substantially affected the formation of three cadmium silicates, namely monoclinic CdSiO3, orthorhombic Cd2SiO4, and tetragonal Cd3SiO5. CdSiO3 formed only in Г = 1.0 systems. Cd2SiO4 was dominant in all reactive systems. In Г = 3.0 systems, Cd3SiO5 rather than Cd2SiO4 was the predominant Cd-hosting product at temperatures above 850 °C. Leaching test results demonstrated that CdSiO3 possessed the highest acid resistance among the cadmium silicates. The leachability of Cd2SiO4 was very similar to that of Cd3SiO5. CdSiO3 preferred incongruent dissolution, whereas Cd2SiO4 and Cd3SiO5 favored near-congruent dissolution. This study delineated the feasibility of cadmium incorporation by Si-rich matrices, identifying a promising approach for cadmium detoxification.

Mineral chemistry and phase equilibrium constraints on the origin of accretions formed during copper flash smelting

This paper delves into the constraints on the nature, origin and thermal evolution of the accretions formed in the uptake shaft of the flash smelting furnace operated by Atlantic Copper in Huelva, Spain, outlining recommended practices for preventing accretion buildup. The accretions were investigated using quantitative electron probe microanalysis, X-ray diffraction and digital imaging techniques, and the experimental data on mineral composition, crystal chemistry and textural relationships were interpreted in terms of thermodynamic phase equilibrium in the SiO2-Fe-O-S system. The results suggest that two distinct types of accretions were formed by the fractional crystallization of two coexisting immiscible melts, under changing conditions of oxygen partial pressure (pO2). The type I accretion of magnetite + delafossite ± cuprite ± tridymite ± metallic copper crystallized from a fractionating copper-rich melt at pO2 above about 10−5 atm, while the type II accretion of magnetite + fayalite + metallic copper + chalcocite derived from a melt with lower copper concentration when pO2 levels dropped below that critical level. Phase compositions and textures were consistent with a cooling history of both compositionally contrasting liquids from about 1,250 °C, the liquidus temperature of magnetite, to eutectic or near-eutectic temperatures of around 1,100 °C. The maintenance of appropriate temperatures — above the liquidus temperature of magnetite — and oxygen partial pressure levels may be critical for the prevention of accretion buildup.

Accuracy and application of quantitative X-ray diffraction on the precipitation of struvite product

Struvite (MgNH4PO4·6H2O) crystallization from wastewater can gain a great advantage for phosphorus recovery and recycling. Although the recovery process and reaction modeling have been investigated, few studies have been conducted to quantify the different phases in recovered phosphorus products. The quantitative X-ray diffraction (QXRD) technique was employed in the present study to quantitatively determine the crystal phases and amorphous content of recovered struvite-containing products. Substantial mixed phase samples (i.e. struvite, newberyite and amorphous phase) were prepared to perform quantitative analysis to calibrate against known phase composition information by Rietveld refinement on powder X-ray diffraction data. The results showed a high level of accuracy (mean error = ∼3%) in our quantification model and validated the use of the Rietveld method to quantify the amorphous and crystal phases in the struvite-containing products. In addition, the influence of N:P molar ratio on struvite crystallization suggested that the weight percentage of struvite increased from 52% to 93%, when the N:P molar ratio was elevated from 0.2:1 to 1.2:1. This finding suggested the effectiveness of QXRD in facilitating the recovery of quality struvite products from waste streams.

Mineralogy of Furnace Deposits Produced by South African Coals during Pulverized-Fuel Combustion Tests

Pilot-scale combustion tests were carried out on coals with low (13.5%) and high (39.6%) ash percentages from the Highveld Coalfield of South Africa, using the ALS-ACIRL 100–200 kW Combustion Test Facility. The mineral matter in the feed coals and also the chemistry and mineralogy of the ash deposits from different parts of the test furnace were analyzed using quantitative X-ray diffraction and X-ray fluorescence techniques, and the results were used to develop an understanding of the mineralogical processes taking place in the different parts of the pulverized-fuel combustion system. Low-temperature oxygen-plasma ashing and quantitative X-ray diffractometry showed that the mineral matter of both coals contained abundant kaolinite, lesser but still very significant proportions of quartz and carbonates (ankerite and calcite), and minor proportions of pyrite and other minerals. A small but significant proportion of nonmineral Ca also occurs in the organic matter, especially of the low-ash coal. The chemical composition of the combustion products taken from the different sampling points in the test facility (slagging panels, furnace ash, and fouling probes, etc.) was overall very similar for each coal sample. However, the percentages of the different crystalline minerals in the combustion products showed a wide range of variation at the different sampling points. Anorthite, derived from interaction between Ca and the aluminosilicate components, was formed from both coals at temperatures above 1300 °C, mostly as part of sintered aggregates that built up and became detached from the slagging panel in the highest temperature part of the combustion system. Anhydrite was formed by interaction of Ca with SO2; lime and periclase were also formed from the low-ash coal, where insufficient sulfur was available for complete sulfate development.

Calcined kaolinite–bentonite clay blends as supplementary cementitious materials

In an effort to limit the environmental impact of concrete materials, there is increasing interest in the development and use of a wider range of minerals as acceptable supplementary cementitious materials (SCMs). This study investigated calcined blended clays of kaolinite and bentonite, with impurities, to assess their feasibility as SCMs. The combined use of Rietveld quantitative x-ray diffraction (RQXRD) and thermogravimetric analysis (TGA) techniques proved useful in initially gauging amorphous content post-calcination, lending insight into the relationship between calcination temperature and pozzolanic reactivity. The results demonstrated that for the calcined blended clays, as the amorphous content increased, the SCM consumed more portlandite and the compressive strength of cement-SCM mortars increased. Blends of kaolinite–bentonite clays, containing initially 35wt.% crystalline kaolinite prior to calcination, achieved roughly 10% increase in compressive strength over samples containing 100wt.% cement, at 90days. Blended kaolinite SCMs may offer significant advantages as a low-cost alternative binder or cement replacement material, with the ability to maintain or enhance mechanical strength.

APPLIED MINERALOGY OF CEMENT & CONCRETE

Maarten A.T.M. Broekmans and Herbert Pollmann, Editors. Reviews in Mineralogy and Geochemistry, Mineralogical Society of America, vol. 74, 364 p. $40 (24% member discount). ISBN 978-0-939950-88-1 (order via http://www.minsocam.org). This interesting and useful book will undoubtedly be a useful reference for anyone interested in the mineralogy of cements and cement-based materials including concrete. Editors Maarten Broekmans and Herbert Pollmann have assembled an excellent compendium of information on mineralogy ranging from calcium aluminate cements to microscopy. Volume 74 of Reviews in Mineralogy and Geochemistry presents in-depth studies of the mineralogy of calcium aluminate cements, mineralogy of clinker and hydraulic cements, quantitative X-ray diffraction techniques applied to cement and cement-based materials, …

Stability of Tricalcium Silicate and Other Primary Phases in Portland Cement Clinker

The decomposition of alite (C3S) in Portland cement clinker was investigated by isothermal annealing, aiming to provide more fundamentals for the cooling process of cement clinker so as to search for potential chance for modification of the ongoing cooling process. Clinker phases were analyzed with quantitative X-ray diffraction technique. Scanning electron microscope and microscopy were used to investigate the microstructure. The fastest decomposition rate appeared at 1125–1150 °C in a temperature–time–transformation diagram. The decomposition of alite primarily occurred at the cracks, edges, and defects of the clinker. The resultant f-CaO segregated, which mainly controlled the decomposition rate of alite. The three-dimensional diffusion model (Jander) was suitable for the decomposition kinetics of alite with a non-Arrhenius behavior for the activation energy which was a piecewise linear function with temperature. Interstitial phases recrystallized during the annealing process, accompanied by an increas...

Mineralization Behavior of Fluorine in Perfluorooctanesulfonate (PFOS) during Thermal Treatment of Lime-Conditioned Sludge

The fate and transport of the fluorine in perfluorooctanesulfonate (PFOS) during the thermal treatment of lime-conditioned sludge were observed using both qualitative and quantitative X-ray diffraction techniques. Two main fluorine mineralization mechanisms leading to the substantial formation of CaF2 and Ca5(PO4)3F phases were observed. They had a close relationship with the thermal treatment condition and the PFOS content of the sludge. At low temperatures (300-600 °C), CaF2 dominated in the product and increases in treatment time and temperature generally enhanced the fluorine transformation. However, at higher temperatures (700-900 °C), increases in treatment time and temperature had a negative effect on the overall efficiency of the fluorine crystallization. The results suggest that in the high temperature environment there were greater losses of gaseous products such as HF and SiF4 in the transformation of CaF2 to Ca5(PO4)3F, the hydrolysis of CaF2, and the reaction with SiO2. The quantitative analysis also showed that when treating sludge with low PFOS content at high temperatures, the formation of Ca5(PO4)3F may be the primary mechanism for the mineralization of the fluorine in PFOS. The overall results clearly indicate the variations in the fate and transport of fluorine in PFOS when the sludge is subject to different PFOS contents and treatment types, such as heat drying or incineration.

Mineralogy of the volcanic-influenced Great Northern coal seam in the Sydney Basin, Australia

The mineralogy of the individual coal plies and intra-seam claystone bands in the Great Northern seam of the Sydney Basin has been evaluated using optical and scanning electron microscopy, and quantitative X-ray diffraction techniques. The uppermost two claystone bands are tonsteins, consisting mainly of well-ordered kaolinite with graupen to vermicular textures. Idiomorphic crystals of K-feldspar within these tonsteins may represent members of the anorthoclase–sanidine series or a sodic sanidine, and indicate an acid to intermediate volcanic ash input. In contrast, the lowermost parting was largely derived from epiclastic sediment, admixed with minor volcanic material such as high-temperature quartz and a different type of K-feldspar component.

Mineralogy of lignites and associated strata in the Mavropigi field of the Ptolemais Basin, northern Greece

The mineralogy of five lignite layers and the associated roof, floor and intercalating strata has been analysed using low-temperature oxygen-plasma ashing and quantitative X-ray diffraction techniques. The lignite contains quartz, kaolinite, illite and smectite, and in some cases small proportions of feldspar, thought to represent mainly detrital minerals in the original peat deposits. One sample also contains crystalline calcium oxalates, with weddellite present in the raw lignite and whewellite in the low-temperature ash (LTA) of the same lignite sample. Minor proportions of gypsum are present in some of the raw lignite samples, possibly in part derived from precipitation of dissolved Ca and SO 4 in the pore waters on drying. All the LTAs, however, contain much higher proportions of bassanite and/or gypsum compared to the other minerals present, consistent with production of calcium sulphate artefacts from interaction of abundant organically-associated Ca and S in the lignite during the plasma-ashing procedure. The inorganic strata are mainly carbonate rocks, consisting almost entirely of calcite with minor aragonite, small proportions of illite, traces of pyrite and in some cases siderite. Some non-carbonate rocks are also associated with the lignite seams; these are dominated by plagioclase feldspar and mica, along with illite, kaolinite and a relatively minor proportion of quartz. The mineral assemblages can be related to the palaeoenvironmental conditions under which the various sediments (including lignite) were deposited. Comparison of the mineral abundances in the samples to the chemical composition of the materials shows that the quantitative XRD technique provides results consistent with ash analysis data. Although abundant in the associated rocks, calcite does not occur in the lignite samples. While part of the relatively abundant Ca in the lignite occurs as either gypsum or weddellite, most of it appears to be organically-bound. Mine products that incorporate calcareous rocks of the type associated with the lignite may, however, contain separate calcite phases and display high carbonate CO 2 contents.

Deformation characteristics of δ phase in the delta-processed Inconel 718 alloy

The hot working characteristics of δ phase in the delta-processed Inconel 718 alloy during isothermal compression deformation at temperature of 950 °C and strain rate of 0.005 s − 1 , were studied by using optical microscope, scanning electron microscope and quantitative X-ray diffraction technique. The results showed that the dissolution of plate-like δ phase and the precipitation of spherical δ phase particles coexisted during the deformation, and the content of δ phase decreased from 7.05 wt.% to 5.14 wt.%. As a result of deformation breakage and dissolution breakage, the plate-like δ phase was spheroidized and transferred to spherical δ phase particles. In the center with largest strain, the plate-like δ phase disappeared and spherical δ phase appeared in the interior of grains and grain boundaries.

Composition and mode of occurrence of mineral matter in some Colombian coals

The minerals in a range of Colombian coal samples, selected to represent the principal coal-mining regions, have been investigated using low-temperature ashing and quantitative X-ray diffraction techniques, and the results compared to information from chemical analysis and Mössbauer spectroscopy studies. Kaolinite, illite, interstratified illite–smectite and quartz are the dominant mineral matter components in almost all of the coal samples, with small but significant proportions of pyrite (up to around 15% of the mineral matter) being present in around half of the samples studied. Other minerals present in particular samples include chlorite, muscovite, paragonite, ankerite, dolomite, calcite and siderite, along with phosphate minerals apatite and goyazite. Jarosite and coquimbite are also noted in some of the pyrite-bearing coals, probably representing oxidation products of the pyrite developed with exposure or storage. Bassanite is present in the low-temperature ash of some coals, and in one sample occurs along with significant concentrations of hexahydrite, alunogen, tschermigite and paraluminite, all of which were probably derived from interaction of inorganic elements in the organic matter with organic sulphur during maceral oxidation. Quantitative analysis of the minerals in the low-temperature ash of the coal samples using Rietveld-based X-ray diffraction techniques provides results that are consistent, at least for the most abundant elements, with the chemical composition of the coal ash as determined by standard analysis procedures. The evaluation of mineral-rich concentrates by Mössbauer spectroscopy also provides results consistent with the XRD data, especially as regards pyrite and some of the sulphate components. Optical microscopy indicates that much of the pyrite, and in some cases also the carbonates, occurs as anhedral crystals, finely disseminated in the maceral components, as aggregates of crystals (including pyrite framboids), as fine-grained crystals replacing liptinite, and as fracture fillings. Some sub-angular to rounded quartz grains are also present, possibly of detrital origin, but most other minerals, including the clay minerals, occur mainly as aggregates of intimately admixed mineral and maceral constituents.

New Phases in the Mg-Al-Sr System

This work presents experimental investigation of 14 different alloys with differential scanning calorimetery (DSC), scanning electron microscopy/energy dispersive spectrometer (SEM/EDS) analysis, quantitative electron probe micro-analysis (EPMA) and X-ray diffraction (XRD) techniques to identify the phases in the Mg-Al-Sr system and to determine their compositions. DSC has permitted real time measurement of the phase changes involved in these systems. The temperature ranges for the phase transformations and enthalpy of melting and enthalpy of formation of the compounds are reported. Comparison between these results and the thermodynamic findings has been discussed. The microstructure of the Mg-Al-Sr-based alloys is primarily dominated by (Mg) and (Al4Sr). The plate-like structure has been identified as Al4Sr. A new ternary intermetallic with chemical composition of 69.9 ± 1.5 at.% magnesium, 19.3 ± 2.0 at.% aluminum and 8.7 ± 0.6 at.% strontium has been identified in three different alloys. This phase was characterized as a large precipitate. Three ternary solid solutions have been observed. The solubility ranges of Al in Mg38Sr9 and Mg17Sr2 are 12.5 and 8.5 at.%, respectively, whereas the solubility of Mg in Al4Sr compound is found to be 23 at.% in the investigated samples. Further, Mg was found to dissolve 11.4 at.% Al at room temperature.

Iron electrodiffusion of bulk YBaCuO superconductor under different magnetic fields

In this study, diffusion mechanism of iron impurities in bulk YBa2Cu3O7 (YBaCuO) superconductor prepared by standart solid state reaction method and its effect on lattice structure under different magnetic field have been examined. Correlation between characteristic X-ray intensities and surface dopant density were investigated. The effects of different magnetic field intensities on crystal structure of iron diffused samples have been investigated by quantitative Energy Dispersive X-Ray Fluorescence (EDXRF) and X-ray Diffraction (XRD) techniques. It was found that Fe diffusion increases with increasing magnetic field.

Cement–clay pastes for stabilization/solidification of 2-chloroaniline

Immobilization of a model liquid organic pollutant, i.e. the 2-chloroaniline (2-CA), into a cement matrix using organoclays as pre-sorbent agents was investigated. Five cement–clay pastes were prepared with different nominal water-to-cement ratios (w/c=0.40, 0.25 and 0.15 wt/wt) and various amounts of waste (waste-to-cement o/c=0.20, 0.60 and 1.00 wt/wt); for comparison, a neat cement paste was also prepared. Dynamic leach tests were performed on solidified monoliths in order to assess the successful immobilization of the 2-CA. In monoliths at constant w/c ratio (0.40) the total amount of pollutant released increases with its initial content, and ranges from 15 to 35% with respect to it. By lowering w/c from 0.40 to 0.15 at constant o/c, the performances improved (<25% released). The microstructure of the hardened cement–clay pastes was characterized by quantitative X-ray diffraction (QXRD) and electronic microscopy (SEM-EDS) techniques; hydration degree was estimated by means of thermogravimetric analysis (TGA) in addition to QXRD. No evidence of any chemical reaction between 2-CA and cement phases was found. Moreover, it was shown that the most important factors affecting the cement hydration process were the total water content, i.e. the one taking also into account the water contained in the wet polluted clay, and the amount of 2-CA not firmly sorbed by the organoclay, and then freely dispersed in the paste.

A MS, SEM-EDX and XRD study of Ti or Cu-doped zinc ferrites as regenerable sorbents for hot coal gas desulfurization

The minerals in a range of Colombian coal samples, selected to represent the principal coal-mining regions, have been investigated using low-temperature ashing and quantitative X-ray diffraction techniques, and the results compared to information from chemical analysis and Mössbauer spectroscopy studies. Kaolinite, illite, interstratified illite–smectite and quartz are the dominant mineral matter components in almost all of the coal samples, with small but significant proportions of pyrite (up to around 15% of the mineral matter) being present in around half of the samples studied. Other minerals present in particular samples include chlorite, muscovite, paragonite, ankerite, dolomite, calcite and siderite, along with phosphate minerals apatite and goyazite. Jarosite and coquimbite are also noted in some of the pyrite-bearing coals, probably representing oxidation products of the pyrite developed with exposure or storage. Bassanite is present in the low-temperature ash of some coals, and in one sample occurs along with significant concentrations of hexahydrite, alunogen, tschermigite and paraluminite, all of which were probably derived from interaction of inorganic elements in the organic matter with organic sulphur during maceral oxidation.Quantitative analysis of the minerals in the low-temperature ash of the coal samples using Rietveld-based X-ray diffraction techniques provides results that are consistent, at least for the most abundant elements, with the chemical composition of the coal ash as determined by standard analysis procedures. The evaluation of mineral-rich concentrates by Mössbauer spectroscopy also provides results consistent with the XRD data, especially as regards pyrite and some of the sulphate components. Optical microscopy indicates that much of the pyrite, and in some cases also the carbonates, occurs as anhedral crystals, finely disseminated in the maceral components, as aggregates of crystals (including pyrite framboids), as fine-grained crystals replacing liptinite, and as fracture fillings. Some sub-angular to rounded quartz grains are also present, possibly of detrital origin, but most other minerals, including the clay minerals, occur mainly as aggregates of intimately admixed mineral and maceral constituents.

PM automotive timing pulley

Single crystals of metastable BCC Ti-6.5 at.% Mo alloy have been aged at 350°C for varying times to precipitate the omega phase. The variation in volume fraction of precipitate was determined by a quantitative X-ray diffraction technique and correlated with transmission electron microscopy from thin foils. For Ti-Mo alloys the lattice misfit between omega and beta phases is small; reflections from parallel planes of both phases overlap necessitating the use of reflections from nonparallel planes. The 310 beta reflection and 3141 and 3032 omega reflections were selected. These two omega reflections occurred at 96° and 105° 2θ angles with CuKα radiation and required a 14° reorientation of the crystal.

Microstructure evolution and thermal properties in nanocrystalline Fe during mechanical attrition

The microstructural evolution and thermal properties of nanocrystalline (nc) Fe during mechanical attrition were investigated by using quantitative X-ray diffraction and thermal analysis techniques. Upon milling of the Fe powders with coarse grains, grain refinement takes place gradually and a steady-state grain size in the nanometer regime is reached after a certain period of milling. With the further milling of the nc Fe within the stage of the steady-state grain size, we observed a grain boundary relaxation process that was manifested by evident decreases in the thermal expansion coefficient and the stored enthalpy, as well as slight decreases in the lattice strain and the Debye–Waller parameter. The grain boundary enthalpy of the nc Fe was estimated, showing a decreasing tendency with the milling time. The present work indicated with clear experimental evidence that the nc materials with the same grain size may exhibit very different properties that depend upon the microstructure of the numerous metastable grain boundaries.