Quartz Phase Research Articles

The Effect of Spent Bleach Earth on the Properties of Sintered Green Glass Ceramic Composite

The purpose of this study is to investigate the effect of spent bleach earth (SBE) loading on the properties of green glass ceramic (GGC) composite. GGC was prepared using SBE and recycled soda lime silicate (SLS) glass. SLS glass was crushed then sieved to approximately 45µm. These GGC composites were formed with different weight fraction of SBE loading (40, 45 and 55 wt.%) by uniaxial dry pressing and sintered at different sintering temperature (700 °C, 750 °C and 850 °C). The sintering temperatures were selected based on Tg of the glass which is around 416 °C. The GGC specimens were analyzed in terms of its physical properties (density, water absorption and porosity), phase presence (X-Ray diffraction) and sintered microstructure (scanning electron microscopy). X-Ray diffraction pattern indicated that cristobalite, quartz and wallastonite phases were formed during sintering. It was found that the GGC with 45 wt.% of SBE loading sintered at 850 °C produced minimum water absorption which was 4.01% accompanied by density of 2.12 g/cm3 and a porosity of 8.49%. This shows that GGC composite produced with considerable higher amount of waste loading able to obtain acceptable physical durability.

Lithofacies and terrestrial sedimentary environments in AMS measurements: case study from Neogene of Oravica River section, Čimhová, Slovakia.

The anisotropy of magnetic susceptibility (AMS) of sedimentary rocks has been used for interpreting wide range of processes: early rock deformations, palaeotransport directions, as well as the evolution of mineral content. Various sedimentary factors which may determine magnetic susceptibility within lacustrine, river, floodplain and swamp deposits have been examined in the Oravica section of the Orava-Nowy Targ Basin. Multiple components of mineral content: illite, chlorite, smectite, kaolinite, quartz and unidentified high susceptibility phase make an AMS interpretation of this content ambiguous. However, this method may be useful for tracing early diagenetic geochemical/microbial processes where iron element is involved. Some sedimentary processes may be recognized from AMS when an assemblage of parameters is studied together: bulk susceptibility, the degree and the shape of anisotropy, principal directions, and the distribution of all these parameters within a set of specimens. Debris-flow processes, as well as lacustrine and floodplain sedimentation are especially well-defined in AMS results. Palaeotransport directions are ambiguous because studied rocks have undergone weak deformation what overprints this sedimentary feature. Most specimens represent an oblate shape of anisotropy and show a good correlation of principal directions and bedding orientation.

Effect of Cu and Zr Co-doped SiO2 Nanoparticles on the Stability of Phases (Quartz-Tridymite-Cristobalite) and Degradation of Methyl Orange at High Temperature

SiO2 nanoparticles doped by 10 mol% Zr and 10 mol% Cu were prepared via the sol-gel method in a controled process. The effects of doping and calcination temperature on the structural and photo-catalytic properties of SiO2 nanopowders were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-Vis absorption spectroscopy. The phases of cristobalite, quartz and tridymite were found at a calcinations temperature range of 800 to 1000 °C and only cristobalite phase was formed at a temperature of 1200 °C. The degradation of methyl orange was examined under visible light radiation indicating that the effect of doped elements (Zr, Cu) on SiO2 reduces the band gap effectively.

Analytical Study of Ancient Pottery from the Archaeological Site of Ban Bo Suak from Nan Province, Thailand

Ban Bo Suak pottery sherds were analyzed by using X-Ray Fluorescence, X-Ray Diffraction and Scanning Electron Microscope. The samples JQA.SH1, FQB.SH3, PQC.SH5 and NQD.SH7, showed that phase structure were quartz, tridymite and mullite phase. It was confirmed that sherds were fired at high temperature more than 1000 °C. As a result, they made the body and glaze compacted and turned into stoneware at high temperature. SEM images of surface showed the middle layers between glaze and body for JQA.SH1 and FQB.SH3. The decoration techniques were glazed and slip layer between bodies and glaze.

Elevated bulk-silica exposures and evidence for multiple aqueous alteration episodes in Nili Fossae, Mars

The Nili Fossae region of Mars contains some of the most mineralogically diverse bedrock on the planet. Previous studies have established three main stratigraphic units in the region: a phyllosilicate-bearing basement rock, a variably altered olivine-rich basalt, and a capping rock. Here, we present evidence for the localized alteration of the northeast Nili Fossae capping unit, previously considered to be unaltered. Both near-infrared and thermal-infrared spectral datasets were analyzed, including the application of a method for determining the relative abundance of bulk-silica (SiO2) over surfaces using thermal emission imaging system (THEMIS) images. Elevated bulk-silica exposures are present on surfaces previously defined as unaltered capping rock. Given the lack of spectral evidence for phyllosilicate, hydrated silica, or quartz phases coincident with the newly detected exposures—the elevated bulk-silica may have formed under a number of aqueous scenarios, including as a product of the carbonation of the underlying olivine-rich basalt under moderate water: rock scenarios and temperatures. Regardless of formation mechanism, the detection of elevated bulk-silica exposures in the Nili Fossae capping unit extends the history of aqueous activity in the region to include all three of the main stratigraphic units.

Crystallization and thermal expansion behavior of lithium zinc silicate sealing glass

Effect of heat treatment schedule on the crystallization and thermal expansion behavior of a lithium zinc silicate glass system was investigated by differential scanning calorimeter (DSC), X-ray diffraction, and linear thermal expansion test. Two well-defined crystallization exothermic peaks were observed from the DSC trace. According to the apparent activation energies and avrami parameter values calculated from the two crystallization exothermal peaks, the first crystallization exothermal peak was attributed to a combining surface and internal crystallization behavior, while the second one was found to be internal crystallization. Additionally, the phase evolution and the thermal expansion behavior with increasing heat treatment temperature were found to be closely related. Interestingly, it was found in comparison with previous reports that addition of CaO varies the phase composition of the resulting glass–ceramic in an opposite way to K2O and the deep rooted reason has been discussed which may cast light on the modulation of properties of glass–ceramic involved crystalline phase of quartz or cristobalite. At last, average thermal expansion coefficient of 7.99–15.38×10−6K−1 in the temperature range of 25–400°C has been obtained with different heat treatment schedules.

Effects of fly ash addition on physical properties of porous clay-fly ash composites via polymeric replica technique

The porous composites of clay and fly ash have the potential to be used in many fields, such as catalyst support and gas adsorbents. In this study, various ratios of fly ash (1–2) with different percentage of suspension (50–70 wt%) were applied to produce porous clay-fly ash composites via polymeric replica technique. Fabrication process starts by mixing clay and fly ash in distilled water to form slurry. The process is followed by fully immersing polymer sponge in slurry. The excess slurry is then removed through squeezing. Finally, the sponge coated with slurry is sintered at 500 and 1250 °C for 1 h. It is found that the compressive strength of porous composites improves significantly (0.178–1.28 MPa) when the amount of clay-fly ash suspension mixture (50–70 wt%) increases. The compressive strength of porous composites is mainly attributed to the mullite, quartz and amorphous phase formations. These results are supported by X-ray diffraction analysis. On the other hand, increase in the amount of suspension reduces the apparent density (from 2.44 to 2.32 g/cm3) and porosity (from 97 to 85 %). The reduction in apparent density is believed to be caused by the presence of high fly ash content in porous composites. The melted fly ash cenospheres have closed the internal pores and increased density of samples. Higher suspension level not only reduces porosity, but also increases close pores of the porous composites. The results are justified through the observation from the structures of porous clay-fly ash composites.

Hidden value in low-cost inorganic pigments as potentially valuable magnetic materials

Inorganic pigments are substances that develop colour in organic solids such as ceramics and glazes, and are usually a complex mixture of oxides, and relatively low-cost. Their chromatic properties have been extensively studied, yet surprisingly the magnetic and electrical properties of these economic and common materials have been neglected, despite the fact many are based on ferrite spinels. Therefore, we investigated these properties in commercial black and brown pigments, to assess their potential as magnetic materials. The brown and black pigments were found to be spinel ferrites, with estimated formulas of Fe1.34Cr0.62Mn0.66Zn0.22Ni0.10Co0.06O4 and Fe1.02Cr0.97Co0.57Mn0.23Ni0.21O4, respectively. The brown pigment also contained a higher amount of SiO2 compared to the black pigment (~7mol% vs. ~2mol%), which appeared as a second phase of crystalline quartz, and adversely affected its porosity, magnetisation and electrical ac conductivity, compared to the black pigment. However, both were very magnetic and very soft ferrites. The brown pigment had Ms=11.7Am2kg−1 and Hc of 1.5kAm−1, with a high electrical conductivity (σ) of 4×10−4−7×10−3Ω−1m−1 between 100Hz and 1MHz. The black pigment was equally magnetically soft, but had a much greater magnetisation and lower electrical conductivity, with Ms=18.7Am2kg−1, Hc=2.4kAm−1, and σ=5×10−6−8×10−5Ω−1m−1 between 100Hz and 1MHz.This work has revealed the potential hidden value of low-cost commercial inorganic pigments based on spinel ferrites as magnetic materials. This demonstrates their potential at low-cost alternative materials for applications such as in power supply transformers, switching materials and sensors, where soft magnetisation is especially important.

Identifying Glass Compositions in Fly Ash

In this study, four Class F fly ashes were studied with a scanning electron microscope; the glassy phases were identified and their compositions quantified using point compositional analysis with k-means clustering and multispectral image analysis. The results showed that while the bulk oxide contents of the fly ashes were different, the four fly ashes had somewhat similar glassy phase compositions. Aluminosilicate glasses (AS), calcium aluminosilicate glasses (CAS), a mixed glass, and, in one case, a high iron glass were identified in the fly ashes. Quartz and iron crystalline phases were identified in each fly ash as well. The compositions of the three main glasses identified, AS, CAS, and mixed glass, were relatively similar in each ash. The amounts of each glass were varied by fly ash, with the highest calcium fly ash containing the most of calcium-containing glass. Some of the glasses were identified as intermixed in individual particles, particularly the calcium-containing glasses. Finally, the smallest particles in the fly ashes, with the most surface area available to react in alkaline solution, such as when mixed with portland cement or in alkali-activated fly ash, were not different in composition than the large particles, with each of the glasses represented. The method used in the study may be applied to a fly ash of interest for use as a cementing material in order to understand its potential for reactivity.

Study of Heat Effect on the Composition of Dunes Sand of Ouargla (Algeria) Using XRD and FTIR

The spectra of x-ray diffraction (XRD) and infrared spectroscopy (FTIR) shows that the dunes sand of Ouargla’s region consists naturally of crystalline structures of α-quartz and gypsum, as well as other uncrystallized compounds with low concentrations like kaolinite and hematite, in addition to some organic compounds. The sand heating process at temperatures between 200 and 1200 °C affects its composition. By heating at 200 °C crystalline phases of anhydrite and bassanite appear due to the continuing loss of water from the gypsum. All the gypsum transforms into anhydrite, and the kaolinite transforms into metakaolin because of the breaking of the OH bond, producing water vapor by heating in the range of 400–800 °C. The heating at 1000 °C disassembles the kaolinite into aluminium-silicon and cristobalite, and leads to the emergence of a new crystalline phase related to wollastonite resulting from the start of a reaction between the anhydride and the quartz. Heating at 1200 °C leads to the disappearance of all the anhydrite because of its interaction with the quartz, producing the wollastonite and the release of sulfur dioxide SO2 and oxygen O2, in addition to the increase of the cristobalite proportion because of the disintegration of all the kaolinite into mullite and cristobalite, or the transformation of quartz phase into cristobalite. Also occuring is an interaction between the hematite and the quartz producing the ferrosilite characterized by its green color.

Evidence from pseudomorphous β-quartz phenocryst for decompression of rock-forming and ore-forming processes in Shapinggou porphyry Mo deposit

The Shapinggou porphyry molybdenum (Mo) deposit, located in Jinzhai County, Anhui Province, China, is the largest in the Qinling-Dabie Mo Metallogenic Belt. The intrusive rocks in the Shapinggou Mo ore district formed in the Yanshanian can be divided into two stages based on zircon U-Pb dating and geochemical features. This study focuses on the late stage intrusions (quartz syenite and granite porphyry), which are closely genetically related to molybdenum mineralization. Petrographic observations identified two quartz polymorphs in the quartz syenite and granite porphyry, which were derived from the same magmatic sources and similar evolutionary processes. The quartzes were identified as a xenomorphic α-quartz within quartz syenite, while the quartz phenocrysts within the granite porphyry were pseudomorphous β-quartz, characterized by a hexagonal bipyramid crystallography. The pseudomorphous β-quartz phenocrysts within the granite porphyry were altered from β-quartz through phase transformation. These crystals retained β-quartz pseudomorph. Combined with titaniumin- zircon thermometry, quartz phase diagrams, and granitic Q-Ab-Or-H2O phase diagrams, it is suggested that the quartz syenite and granite porphyry were formed under similar magmatic origins, including similar depths and magmatic crystallization temperatures. However, the α-quartz within quartz syenite indicated that the crystallization pressure was greater than 0.7 GPa, while the original β-quartz within the granite porphyry was formed under pressures between 0.4 and 0.7 GPa. The groundmass of the granite porphyry which formed after the phenocryst indicated a crystallizing pressure below 0.05 GPa. This indicates that the granite porphyry was formed under repetitive and rapid decompression. The decompression was significant as it caused the exsolution of the ore-forming fluids, and boiling and material precipitation during the magmatic-fluid process. The volumetric difference during the phase transformation from β-quartz to α-quartz caused extensive fracturing on the granite porphyry body and the wall rocks. As the main ore-transmitting and ore-depositing structures, these fractures benefit the hydrothermal alteration and stockwork-disseminated mineralization of the porphyry deposit. It is considered that the pseudomorphous β-quartz phenocrysts of the porphyritic body are metallogenic indicators within the porphyry deposits. The pseudomorphous β-quartzes therefore provide evidence for the formation of the porphyry deposit within a decompression tectonic setting.

Treated Oil Palm Ash as Precursor in the Zeolite Synthesis

In this study, the ability of treated oil palm ash aided with kaolin powder to produce zeolites is studied. The palm ash has been treated with citric acid via a leaching process to get rid of the metallic impurities in it. The usage of treated oil palm ash in the zeolites conversion seems to be an option for waste materials management. Characterization of treated oil palm ash from Malaysia’s palm oil plantation has been cleared. The treated oil palm ash and kaolin powder are used as the starting material for the synthesis of zeolites materials. The method chose for the zeolites conversion is alkaline hydrothermal treatment. The chemical composition, crystalline phases and elemental composition of treated oil palm ash and as-synthesized samples were characterized and studied. From the analysis, the treated oil palm ash was a fertile source of silica and exists as quartz phase. The outcomes have significant motivation for the production of zeolites by using low cost material such as treated oil palm ash.

Water Defluoridation Capacity of Tanzanian Kaolin-Feldspar Blend Adsobents

A study was conducted to investigate the capacity of Tanzanian kaolin-feldspar blends on water defluoridation. Five adsorbents of kaolin-feldspar blends were prepared at different ratios, namely; 1:0, 1:1, 1:2, 2:1 and 0:1.The prepared adsorbents were activated at 60°C and then characterized by XRD and XRF. Mineralogical results showed that kaolin contained phases of kaolinite, illite and quartz whereas feldspar contained microcline and quartz. Chemical composition results indicated that both kaolin and feldspar samples contained silica and aluminium in high proportions. Defluoridation studies were conducted by using column method. Different parameters were tested for water defluoridation studies including particle size, contact time, initial fluoride ion concentration, height of the column and solution pH. It was observed that the adsorption increased with a decrease in particle size, and particle size of 0.25 mm showed the highest removal of fluoride. The fluoride adsorption was found to increase with contact time with optimum contact time after 45 minutes. A high adsorption of fluoride ions for all samples was observed at low pHs (2-6) and the maximum adsorption was at pH 2. Also the adsorption increased as the height of the column was increased. Regeneration of spent adsorbent did not afford to remove fluoride to acceptable levels, an aspect that needs more investigation. The study therefore concludes that, although the blends can be used as defluoridation materials; blending kaolin and feldspar did not improve adsorption of fluoride ions from fluoridated water. The best adsorbent was B1 which consists of kaolin only followed by B2 with 2:1 kaolin-feldspar ratio.

Phase dependent TL–OSL studies in various phases of chemically synthesized Cu doped crystalline SiO2

Cu doped crystalline SiO2 in various phases viz. coesite, pyrite, and cristobalite has been successfully synthesized through the chemical route. All the studied samples show mixed phases and the relative contribution is found to be dependent on the annealing temperature. For sample heated at 300°C the most dominant phase is Coesite whereas for samples heated in the temperature range 500–900°C the dominant phase is pyrite along with the quartz, coesite and cristobalite phase. The Cu+ emission intensity as well as wavelength in all these samples is found to be dependent on the dominant phase as well as relative contribution of other less dominant phases. For sample heated at 300°C in which dominant phase is coesite the emission is observed around 360nm. The samples which are heated in the temperature range 500–900°C in which dominant phase is pyrite shows double humped emission with peaks around 360nm and at 395nm. The study shows that cristobalite phase is detrimental to Cu+ luminescence. Samples in which cristobalite phase is present in large amount, less intense Cu+ luminescence is observed. The TL/OSL also follows the similar trend. Of the several samples, maximum TL/OSL sensitivity is obtained for the 700°C heated sample for which the relative contribution of cristobalite phase is minimum. On the basis of an area integration method; integrated over initial 3s, the OSL sensitivity in this sample is found to be 2.3 times the sensitivity of commercial Al2O3:C.

Thermo-physical properties of selected hard rocks and their relation to microwave-assisted comminution

This paper deals with experimental studies regarding the thermo-physical properties of granite, sandstone and basalt in the temperature range of 25–1000°C. It is shown how phase transitions (e.g. α-β quartz phase transition) influence the texture and stability of these rock types. The results of these measurements and analyses are linked to microwave irradiation tests at 17.5kW power. The measurements demonstrate the strong variation of effects depending on the parameter rock/mineralogy showing possible applications in a mineral processing environment.

Observation of phase transformations in cement during hydration

We report the phase transformations in Portland cement before and after hydration. The hydration mechanism was studied in detail by using a full Rietveld refinement of the X-ray diffraction (XRD) patterns, Fourier Transformed Infra-Red (FTIR) spectroscopy, Thermogravimetric Analysis (TGA) and Mössbauer spectroscopy at room temperature. From the Rietveld refinement of XRD data, alite, belite, celite, brownmillerite and low quartz phases were detected and quantified as major phases in dry cement powder. After hydration, calcium carbonate, portlandite and ettringite phases were found to form. A large reduction in the amounts of alite and belite phases were observed suggesting the formation of amorphous C–S–H phase and emphasizing the role of alite phase in flash setting of cement, as justified by the XRD and FTIR spectroscopy. Mössbauer spectra of all the unset samples showed quadrupole split doublets corresponding to the brownmillerite phase which remains unchanged even after about one week of hydration, suggesting that brownmillerite did not transform to other phases during initial stage of hydration process.

Synthesis of ZSM-5 from impure and beneficiated Grahamstown kaolin: Effect of kaolinite content, crystallisation temperatures and time

Raw kaolin obtained from Grahamstown, South Africa was beneficiated using wet sieving and filtration before use in the synthesis of ZSM-5 zeolite via hydrothermal treatment at various temperatures (120–190°C) and times (24–96h) under autogenous pressure. The impacts of kaolinite content and crystallisation parameters (i.e. temperature and time) on ZSM-5 formation were investigated. The mineralogical phases, morphology, surface area and porosity characteristics of the synthesised materials were investigated using XRF, XRD, FT-IR, HRSEM-EDS and N2 physisorption (BET) analyses. Catalytic tests were carried out in a fixed bed reactor, WHSV of 8h−1 and a temperature of 350°C at atmospheric pressure using 1-hexene as a feed. Beneficiation decreased the impurity content in the clay and increased kaolinite content which resulted in the formation of pure ZSM-5 zeolite. XRD and HR-SEM revealed that ZSM-5 synthesised from raw kaolin contained quartz and formed a ZSM-5/quartz coated composite. Temperature and time were critical in controlling phase purity and crystallinity of ZSM-5. At a synthesis temperature of 190°C ZSM-5 transformed into a more thermodynamically stable quartz phase. The optimum condition for synthesising pure ZSM-5 from this clay was found to be 150°C for 48h. Morphology, surface area and porosity of ZSM-5 changed with an increase in crystallisation time. ZSM-5 with a high external surface area and presence of mesopores were observed in products synthesised at 150°C for 24h. Microporosity further developed as time increased and the ZSM-5 became more crystalline. The catalyst performance studies indicated that the ZSM-5 synthesised from raw and beneficiated kaolin at crystallisation conditions 150°C and 48h had good 1-hexene transformation activity and high selectivity to gasoline range hydrocarbons. The presence of quartz in the catalyst enhanced catalyst stability and selectivity to C10+ hydrocarbons.

Effect of sintering temperatures on properties of BaO–B2O3–SiO2–Al2O3 glass/silica composites for CBGA package

BaO–B2O3–SiO2–Al2O3 (BBSA) glass/silica composites synthesized by solid-state reaction method were developed for CBGA packages, and the effects of sintering temperature (900–950 °C) on the phase transformation, microstructure, thermal, mechanical and electrical properties were investigated. XRD results show that the major phases quartz and cristobalite, and the minor phase BaSi2O5 are detected in BBSA composites. Furthermore, it was found that the quartz phase transforms to cristobalite phase at 930–940 °C. The formation of cristobalite phase with higher coefficient of thermal expansion (CTE) led to the increase of CTE value of BBSA composites. However, excessive cristobalite phase content would degrade the mechanical properties and the linearity of thermal expansion of the ceramics. BBSA composites sintered at 920 °C exhibited excellent properties: low dielectric constant and loss (er = 6.2, tanδ = 10−4 at 1 MHz), high bending strength (179 MPa), high CTE (12.19 ppm/°C) as well as superior linearity of the thermal expansion.

The sequel of modified fly ashes using high energy ball milling on mechanical performance of substituted past cement

ABSTRACT The consideration of planetary ball mill processing is attempted to obtain modified fly ashes powders that are used as substitutes in a cement paste. Ball milling conditions are related to structural modifications of processed powders. These modifications are retrieved from X-ray diffraction, infrared spectroscopy, powder granulometry, and scanning electron microscopy. As an industrial application, the milled fly ashes are substituted to two different cements to show possible effect on compressive strength of cement pastes. Structural analysis of milled fly ashes show loss of crystallinity of the magnetite phase, nanosizing trend of quartz and mullite phases with some straining that takes place after only 1 h of milling. The drop of particle size of the milled fly ashes is also evidenced but with tendency to agglomeration and particle shape modification from spherical to irregular forms. Mechanical performance results related to modified cement pastes indicate successful substitution of cements by milled fly ashes up to 50%. Substitution results in levels of compressive strength as large as 70 MPa for particular combination of milling time, fly ash content and curing time.

MAGMATIC Au MINERALIZATION AT THE BILIHE Au DEPOSIT, CHINA

Most known primary Au deposits are produced by hydrothermal processes. In this paper, we report Au mineralization of magmatic origin in the Bilihe deposit, China (8.5 Mt averaging 2.9 g/t Au). At Bilihe, most (>70%) native Au (no detectable Ag) grains are euhedral or subspherical in shape, and occur as trails in dendritic quartz phenocrysts and comb-layered quartz in a moderately reduced, highly fractionated diorite-granite intrusion. The hosting quartz typically has a dendritic core (Q1) and a rim (Q2), with Q1 having concentric zoning and sector zoning in cathodoluminescence (CL) images. Cathodoluminescence petrography and crystallographic modeling reveal that most of the Au trails occur along intersecting crystallographic planes of the host quartz, indicating simultaneous precipitation of both Au and quartz. Abundant melt inclusions are present in Q2 with >950°C homogenization temperatures. Minor Au grains also occur in melt inclusions in quartz. In rare cases, necking of Au melt inclusions is present. Neither Q1 nor Q2 contain primary fluid inclusions; only secondary fluid inclusions were found in healed cracks. The above observations indicate a direct magmatic (quartz phenocryst phase) origin for the Au. This defines a new type of Au deposit, and thereby opens new potential for Au exploration. The magmatic origin of Au at Bilihe also implies that enrichment of Au may occur in a source melt prior to volatile escape, which would enhance the possibility of forming a magmatic-hydrothermal Au deposit.