Alunite Research Articles

Changing role of EMS \u2013analyses of non-conveyed and conveyed patients in Finland

BackgroundEmergency Medical Services (EMS) and Emergency Departments (ED) have seen increasing attendance rates in the last decades. Currently, EMS are increasingly assessing and treating patients without the need to convey patients to health care facility. The aim of this study was to describe and compare the patient case-mix between conveyed and non-conveyed patients and to analyze factors related to non-conveyance decision making.MethodsThis was a prospective study design of EMS patients in Finland, and data was collected between 1st June and 30th November 2018. Adjusted ICPC2-classification was used as the reason for care. NEWS2-points were collected and analyzed both statistically and with a semi-supervised information extraction method. EMS patients’ geographic location and distance to health care facilities were analyzed by urban–rural classification.ResultsOf the EMS patients (40,263), 59.8% were over 65 years of age and 46.0% of the patients had zero NEWS2 points. The most common ICPC2 code was weakness/tiredness, general (A04), as seen in 13.5% of all patients. When comparing patients between the non-conveyance and conveyance group, a total of 35,454 EMS patients met the inclusion criteria and 14,874 patients (42.0%) were not conveyed to health care facilities. According the multivariable logistic regression model, the non-conveyance decision was more likely made by ALS units, when the EMS arrival time was in the evening or night and when the distance to the health care facility was 21-40 km. Furthermore, younger patients, female gender, whether the patient had used alcohol and a rural area were also related to the non-conveyance decision. If the patient’s NEWS2 score increased by one or two points, the likelihood of conveyance increased. When there was less than 1 h to complete a shift, this did not associate with either non-conveyance or conveyance decisions.ConclusionsThe role of EMS might be changing. This warrants to redesign the chain-of-survival in EMS to include not only high-risk patient groups but also non-critical and general acute patients with non-specific reasons for care. Assessment and on-scene treatment without conveyance can be called the “stretched arm of the emergency department”, but should be planned carefully to ensure patient safety.

Variability of Alunite Quartzite Composition as a Reflection of the Characteristics of Its Genesis

Based on 5000 analyses of geological prospecting samples from four alunite deposits (Began’, Ukraine; Haft Sanduq, Iran; Bolshaya Kremenyukha and Kachar, Kazakhstan) and 6000 microprobe analyses of alunite, the features of changes in three parameters of alunite quartzite composition have been studied: (1) alunite content, (2) mole fraction of K in alunite, and (3) correspondence of the amount of K and Na to that of alunite sulfur. All three parameters are highly variable. A linear correlation between them has been identified in over half of the exploration workings. This correlation is sometimes very strong, approaching a functional relationship, especially for two: the alunite content and mole fraction of K in alunite. In the first three of the above-mentioned deposits, this correlation is almost always positive, and in the last, it is always negative. In other words, as alunite content increases, it becomes higher-K in the first case and higher-Na in the second case. Alunite quartzite makes up a regular zone of the infiltration metasomatic column of sulfuric acid alteration in aluminosilicate rocks under conditions apparently close to isothermal. However, the highly variable contents of the basic minerals (alunite and quartz) and alunite composition point to a difference between the alunite quartzite formation model and the theoretical model for isothermal infiltration metasomatic rock. According to the theoretical model, the solution and rock compositions mainly change at the boundaries of the metasomatic zone, whereas the rock and mineral compositions are not characterized by significant variations within the zone. During alunite quartzite formation, the solution and rock compositions change not only at the boundaries, but also within the zone due to ongoing oxidation of sulfur compounds in the solution with the sulfate formation. An increasing sulfate concentration leads to the solution becoming supersaturated in relation to alunite and causes its precipitation, with filling of voids and displacement of quartz. Cooling, heating, or a change in the composition of the hydrothermal system solutions lead to temporal variations in the K/Na ratio in precipitated alunite. Alunite formation inside the alunite zone, accompanied by changes in the mole fraction of K in deposited alunite, is the reason for the high variability of the alunite quartzite composition and for the correlation between the alunite content and its mole fraction of K. If the contribution of higher-K alunite to the variability of its total content is higher than that of higher-Na alunite, a positive correlation is likely to appear, otherwise a negative correlation is more probable.

Viscosity and structure evolution of CaO–SiO2-based mold fluxes with involvement of CaO–Al2O3-based tundish fluxes

In this study, the effect of involvement of CaO–Al2O3–SiO2–MgO tundish flux into CaO–SiO2–Al2O3–Na2O–CaF2 mold flux on viscosity and structure of mold flux was investigated through employing the rotating viscometer and associated structure analysis including high resolution Raman spectroscopy and solid-state 27Al magic angle spinning nuclear magnetic resonance (27Al MAS-NMR). The results showed that the viscosity continuously increases with increasing involvement of tundish flux. The apparent activation energy obtained from the temperature dependence of the viscosity presents an increase from 128.5 kJ/mol to 149.1 kJ/mol with increase of involvement ratio from 0 to 0.75. Semi-quantitative analysis using the deconvoluted Raman spectra and 27Al MAS-NMR spectra revealed an increase in amounts of [AlO4] and Si–O–Al units, but in the meanwhile a decrease in amounts of [AlOnF4-n] and [AlO5] units, this indicates the structure transformation from prevalent silicate structure to complex alumino-silicate structure with increasing involvement ratio. A self-developed structurally-based viscosity model can predict the viscosity of mold flux with varying involvement ratio and presents a smallest deviation of 15.8% compared to those prevalent viscosity models despite of the great transformation of the melt from silicate system to alumino-silicate system.

Mechanical and Transport Properties of High Volume UFA Cement Composites

In this study, mechanical activation is used to generate ultra-fine fly ash (UFA) for high volume fly ash（FA）cement composites. The effects of different content and medium particle size of FA on mortar`s electrical resistivity, chloride penetration and mechanical properties are investigated. The results show that the compressive strength and resistance to chloride permeability of specimens with UFA have been enhanced, owing to higher pozzolanic reaction and higher dissolution rate of Si and Al units of UFA to accelerate the generate of reaction products. However, At the early ages, electrical resistivity of specimens increases with the increase of UFA; at later ages, specimens have a higher electrical resistivity with the increase of UFA.

Novel extraction of valuable metals from circulating fluidized bed-derived high-alumina fly ash by acid–alkali–based alternate method

The recycling of valuable metals from circulating fluidized bed (CFB)-derived high-alumina fly ash (HAFA) paves the way for ash utilization with high economic benefits. However, obtaining an ideal extraction ratio for metals using a single acid treatment under moderate conditions is difficult. A moderate acid–alkali–based alternate method was used in this study to extract aluminum (Al) from CFB-derived HAFA. The dissolution behavior of lithium (Li), gallium (Ga), and rare earth elements (REY) was investigated. The characteristics of leaching residues were studied by XRD, 27Al and 29Si MAS NMR, BET, and SEM-EDS. Results show that Al in the units with low degree of polymerization distributed on the particle surface was preferentially dissolved in the HCl solution. HCl could not penetrate the particle interior and thus greatly limited the improvement of the Al extraction ratio. NaOH solution effectively removed SiO2 that accumulated on the particle surface and broke the Si–O–Al units in the residues. The exposed and liberated Al was further extracted with the HCl solution. Finally, 78% of Al2O3, 80% of Li, 72% of Ga, and 55% of REY in the ash were extracted with the HCl solution. Moreover, 63% of SiO2 in the ash was dissolved in the NaOH solution. The acid leaching residue presented abundant mesopores and a high specific surface area of 205 m2/g. The findings imply that the proposed method that combines the extraction of valuable metals and the preparation of mesoporous materials provides a new way to utilize CFB-derived HAFA.

Перспективная оценка месторождений алунитов в Амурской области (на примере Буриндинского проявления)

Перспективная оценка месторождений алунитов в Амурской области (на примере Буриндинского проявления)

The Matrix Effect and Application of the Multi-Parameter Optimization Method for X-Ray Spectrometric Determination of the Quantitative Composition of Clays

Determining the quantitative composition of clay samples with X-ray fluorescent spectrometry is complicated because of the matrix effect, in which any element can increase or decrease the analytical signals of other elements. In order to predict the properties of clays, it is essential to know their precise chemical composition. Therefore, using the standard addition method was determined calibration and empirical influence coefficients, as well as the true composition of the elements. Farther, these coefficients were used to correct the matrix effect and develop a multi-parameter optimization method. It was determined that in clay samples, consisting of Si, Al, Fe, K, Mg, Ca, Na and Ti oxide formula units, the most significant contribution for matrix effect correction calculations was from the calibration coefficients. Moreover, the largest deviation from the X-ray fluorescent data and true values was determined in the MgO and Na2O cases. In this study was established, that the developed multi-parameter method can be successfully applied to determine the quantitative chemical composition of clay samples of similar compositions.

Highly mesoporous IM-5 zeolite prepared by alkaline treatment and its catalytic cracking performance

Abstract IM-5 zeolite is a high-silica shape-selective zeolite that is expected to replace ZSM-5 in some petrochemical process. Herein, highly crystalline mesoporous IM-5 was successfully prepared by alkaline treatment, and changes in the structure and acid properties were characterized using XRD, XRF, XPS, SEM, TEM, N2 physical adsorption, Py-IR, 29Si NMR and 27Al NMR. The 29Si and 27Al MAS NMR characterization results indicate that the Si(4Si,0Al) units were preferentially removed from the IM-5 framework during the alkaline treatment, and a small amount of the framework Al was eluted. Meanwhile, desilication and dealumination during the treatment resulted in the loss of strong acid sites. Under optimal conditions, the mesopore volume of mesoporous IM-5 increased relatively by 178% from 0.112 cm3 g−1 of the untreated IM-5 to 0.311 cm3 g−1, while the micropore volume decreased slightly, indicating its microporous structure was mostly preserved. Although introducing mesopores decreased the acid amount of IM-5, it possessed better diffusion performance. Thus, mesoporous IM-5 exhibited higher light olefins yield (especially propylene) and catalyst lifetime in catalyzing n-alkane than conventional IM-5 and ZSM-5. Furthermore, the higher gasoline yield and lower coke yield over mesoporous IM-5 were obtained than conventional IM-5 in the heavy oil cracking. Interestingly, compared with ZSM-5 with the same SiO2/Al2O3 ratio, the higher acid strength and more B acid site give IM-5 better catalytic performance with higher catalytic activity and higher yields for light olefins and i-butane.

Alunite Ore Development in the Amur Region

The constructed economic-and-geological model of a commercial alunite deposit in the Amur Region (in terms of Burinda mineralization) includes two scenarios based on the criteria of alumina requirements in and development profitability. The production infrastructure involves open pit mining and processing based on reduction and alkaline treatment in a unified circuit with synnyrite. The calculations show that construction of a mining and processing plant at the deposit is profitable in both scenarios.

Local and Average Structural Changes in Zeolite A upon Ion Exchange

The infamous ‘structure–property relationship’ is a long-standing problem for the design, study and development of novel functional materials. Most conventional characterization methods, including diffraction and crystallography, give us a good description of long-range order within crystalline materials. In recent decades, methods such as Solid State NMR (SS NMR) are more widely used for characterization of crystalline solids, in order to reveal local structure, which could be different from long-range order and sometimes hidden from long-range order probes. In particular for zeolites, this opens a great avenue for characterization through studies of the local environments around Si and Al units within their crystalline frameworks. In this paper, we show that some structural modifications occur after partially exchanging the extraframework Na + ions with monovalent, Li + , K + , Rb + and NH 4 + and divalent, Ca 2 + cations. Solid state NMR is deployed to study the local structure of exchanged materials, while average stricture changes can be observed by powder diffraction (PXRD). To corroborate our findings, we also employ Fourier Transform Infrared spectroscopy (FT-IR), and further characterization of some samples was done using Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray spectroscopy (EDX).

Mimicking Base Interaction with Acidic Sites [Si–O(H)–Al] of Zeolites in Molecular Models

LiAlH4, LiAlMe4, or NaAlH4 react with commercially available HOSiR3, (–OSiR3 = –OSitBuMe2, –OSiPh3) to afford [Li(THF)2][Al(OSitBuMe2)4] (1), [Na(THF)2][Al(OSitBuMe2)4] (2), and [Li(THF)4][Al(OSiPh3)4] (3). Ligand exchange reactions at the alkali metal ions in 1 and 3 with pyridine, 2,2′‐bipyrimidine, and water yielded complexes [Li(py)2][Al(OSitBuMe2)4] (4), [Al(OSitBuMe2)4Li(H2O)]2(bpym) (5), and [Li(THF)(H2O)][Al(OSiPh3)4] (6). The X‐ray crystal structures of complexes 1, 3, 4, 5, and 6 are presented. The complex [quinuclidineH][Al(OSitBuMe2)4] (7), was produced via reaction of quinuclidine·hydrochloride with 2. It features a hydrogen bonding interaction between an N–H group with a Si–O–Al unit, as proposed for the surfaces of zeolites after base treatment.

Layer-by-Layer Molecular Assemblies for Dye-Sensitized Photoelectrosynthesis Cells Prepared by Atomic Layer Deposition.

In a dye sensitized photoelectrosynthesis cell (DSPEC), the relative orientation of the catalyst and chromophore plays an important role in determining the device efficiency. Here we introduce a new, robust atomic layer deposition (ALD) procedure for the preparation of molecular chromophore-catalyst assemblies on wide bandgap semiconductors. In this procedure, solution deposited, phosphonate derivatized metal complexes on metal oxide surfaces are treated with reactive metal reagents in the gas phase by ALD to form an outer metal ion bridging group, which can bind a second phosphonate containing species from solution to establish a R1-PO2-O-M-O-PO2-R2 type surface assembly. With the ALD procedure, assemblies bridged by Al(III), Sn(IV), Ti(IV), or Zr(IV) metal oxide units have been prepared. To evaluate the performance of this new type of surface assembly, intra-assembly electron transfer was investigated by transient absorption spectroscopy, and light-driven water splitting experiments under steady-state illumination were conducted. A SnO2 bridged assembly on SnO2/TiO2 core/shell electrodes undergoes light-driven water oxidation with an incident photon to current efficiency (IPCE) of 17.1% at 440 nm. Light-driven water reduction with a ruthenium trisbipyridine chromophore and molecular Ni(II) catalyst on NiO films was also used to produce H2. Compared to conventional solution-based procedures, the ALD approach offers significant advantages in scope and flexibility for the preparation of stable surface structures.

The utilization of Şaphane alunite in geopolymer production

The aim of this work is to research the usage of alunite from the alunite deposits of Şaphane-Kutahya (Turkey) as a raw material in the production of a geopolymer material. Alunite samples were characterized and prepared to use in body recipes. Manufacturing of geopolymer was conducted by mixing alumina silicate sources, silica fume, and sodium silicate solution. The geopolymer samples were cured at 60 °C for 24 h. Chemical and microstructural characterization of materials prepared from representative samples was carried out using X-ray fluorescence (XRF), X-ray diffraction (XRD), 27Al-magic angle spinning nuclear magnetic resonance (27Al MAS-NMR), and scanning electron microscopy (SEM), techniques, respectively. The compressive strength of the geopolymer materials was obtained from the samples after 7 and 28 days. Compressive strength measurements show a maximum strength of almost 48 MPa after 28 days. As a result of this study, it has been shown that alunite minerals can be utilized as alternative raw materials for production of geopolymer mortars.

Transition of Blast Furnace Slag from Silicate-Based to Aluminate-Based: Structure Evolution by Molecular Dynamics Simulation and Raman Spectroscopy

To determine the effect of Al2O3 content and Al2O3/SiO2 mass ratio on the structure of molten aluminosilicate systems, CaO-SiO2-Al2O3-MgO-TiO2 systems were investigated by conducting molecular dynamics (MD) simulation and Raman spectroscopy. The capabilities of different elements to attract O on the basis of bond length are ranked as follows: Si > Al > Ca. The CNSi-O (approximately 4) and the average CNAl-O (approximately 4.09) demonstrate that the [AlO4] tetrahedron is not as stable as the [SiO4] tetrahedron and that some highly coordinated Al units exist in the slags. Non-bridging oxygen prefers to be coordinated with Si, and Al tends to be localized in polymerized environments as a network intermediate phase. In addition, Ca2+ is more energetically active than Mg2+ as the charge compensation ion. MD results and Raman analysis show that an increase in Al2O3 content complicates the structure at a fixed CaO/SiO2 ratio. In addition, the viscosity of the sample may increase with increasing Al2O3 content but is also influenced by polymerization strength. The substitution of Al2O3 for SiO2 simplifies the structure of the slag at a fixed CaO concentration when Al2O3/SiO2 is less than 0.92, as indicated by the (Q4 + Q3)/(Q2 + Q1) ratio of Al and the structure complexity. The results of MD and Raman analysis agree with those of viscosity measurement.

Pressure induced elastic softening in framework aluminosilicate- albite (NaAlSi3O8).

Albite (NaAlSi3O8) is an aluminosilicate mineral. Its crystal structure consists of 3-D framework of Al and Si tetrahedral units. We have used Density Functional Theory to investigate the high-pressure behavior of the crystal structure and how it affects the elasticity of albite. Our results indicate elastic softening between 6–8 GPa. This is observed in all the individual elastic stiffness components. Our analysis indicates that the softening is due to the response of the three-dimensional tetrahedral framework, in particular by the pressure dependent changes in the tetrahedral tilts. At pressure <6 GPa, the PAW-GGA can be described by a Birch-Murnaghan equation of state with = 687.4 Å3, = 51.7 GPa, and = 4.7. The shear modulus and its pressure derivative are = 33.7 GPa, and = 2.9. At 1 bar, the azimuthal compressional and shear wave anisotropy = 42.8%, and = 50.1%. We also investigate the densification of albite to a mixture of jadeite and quartz. The transformation is likely to cause a discontinuity in density, compressional, and shear wave velocity across the crust and mantle. This could partially account for the Mohorovicic discontinuity in thickened continental crustal regions.

The impact of a freestanding ED on a regional emergency medical services system

ObjectiveThe objective of the study is to examine the effect of the opening of a freestanding emergency department (FED) on the surrounding emergency medical services (EMS) system through an examination of EMS system metrics such as ambulance call volume, ambulance response times, and turnaround times. MethodsThis study is based on data from the county's computer-aided dispatch center, the FED, and the Maryland Health Services Cost Review Commission. The analysis involved a pre/post design, with a 6-month washout period. The preintervention period was April to October 2010, and the postintervention period was April to October 2011. Data were analyzed using standard t tests. ResultsThe average daily number of EMS-related calls received in the computer-aided dispatch center was lower after the FED opened (16.3 [95% confidence interval {CI}, 15.7-16.9] vs 15.8 [95% CI, 14.9-16.9]). One-fourth of all patients were transported by ambulance to the FED after it opened. Use of the FED and adjacent hospitals increased by 8647 visits (15.8%) during the study period. Turnaround time for the county's ALS units decreased from 26.8 (95% CI, 26.2-27.5) to 25.1 (95% CI, 24.3-25.8) minutes. The ambulance out-of-service interval decreased from 87.3 (95% CI, 86.0-88.5) to 81.1 (95% CI, 79.7-82.4) minutes. Based on change in out-of-service this study had a small effect size (Cohen's d = 0.33). ConclusionsThe opening of an FED was associated with a modest improvement in time-specific EMS system metrics: a decrease in ambulance turnaround time and shorter out-of-service intervals.

Abstract 19833: A New Therapeutic Strategy for Refractory Cardiac Arrest Including Prehospital Ecmo: A Comparison Study

Introduction: ECMO is a treatment of refractory cardiac arrest (RCA). The survival rate depends directly on the low flow (LF) period. To reduce LF we have implemented a new RCA management strategy. This work aims to evaluate the impact of this strategy on survival. Methods: This is an observational retrospective single-center study. The ECMO team is composed of a doctor, a nurse and a paramedic.The ethical committee validated the study. During period 1 (11 / 2011-12 / 2014), the strategy associated an ECMO team alert after 10 min of ALS, followed by the implementation of ECMO either in-hospital or out of hospital depending on the ECMO team availability. During period 2 (01-06 / 2015), the strategy associated an ECMO Team alert at the departure of the BLS Ambulance, with a dedicated ECMO team 24/24 H, and a systematic assessment for ECMO implementation either in hospital or out of hospital according to logistical constraints. A specific training was given to dispatch centers, and all ALS units. Qualitative variables were compared using the χ2 and Fisher exact tests, whereas quantitative variables were compared by Wilcoxon tests. Results: The results are in Table 1. The characteristics are similar. The significant results when comparing periods 1 and 2 include an increased survival rate, a decreased LF. Conclusions: The survival rate of RCA treated with ECMO depends on the LF. Unfortunately even by performing a single scoop and run strategy, an important proportion of patients can not be rapidly put on ECMO. We have developped a LF reduction strategy involving the implementation of ECMO either in hospital or in the out of hospital setting. The optimization of this strategy by an earlier alert, a dedicated ECMO team and training has a major significant impact on survival. This increase of survival is probably correlated to the decrease of the LF, especially in the prehospital group. These results need to be confirmed by a RCT comparing in hospital and out of hospital ECMO implementation.

Glass structure and NIR emission of Er3+ at 1.5 μm in oxyfluoride BaF2–Al2O3–B2O3 glasses

The glass structure, photoluminescence properties of Eu3+, Judd–Ofelt analysis, and near infrared emissions of Er3+ at 1.5μm in the oxyfluoride glasses and glass–ceramics of 1Eu2O3- or 1Er2O3-doped 50BaF2–xAl2O3–(50−x)B2O3 (x=0–25mol%) were investigated. It was clarified on the ground of Raman scattering spectroscopy and F1s and O1s XPS measurements that the glass with no Al2O3 (1Er2O3–50BaF2–50B2O3) is composed of BO3, BO2F and BO3F units with F–Ba bonds. The glasses with 25Al2O3 (1Er2O3–50BaF2–25Al2O3–25B2O3) is mainly composed of BO3− and Al(O,F)x units. Existence of non-bridging oxygen was not detected by O1s-XPS spectra. It was proposed that these structures are largely affected on crystallization behavior, e.g., the glass with no Al2O3 forms BaF2 and β-BaB2O4 due to Ba–F bonds and the glass with 25Al2O3 forms BaAlBO3F2 because the glass structure composed of BO3 and Al(O,F) units is similar to the BaAlBO3F2 crystal structure. Judd–Ofelt parameters of Er3+ and Eu3+ in the glasses showed almost the same values in Ω4 and Ω6 for each glass, on the other hand Ω2 decreased with addition of Al2O3. The emission spectra of Er3+ at 1.5μm in the glasses and glass–ceramics with BaAlBO3F2 crystals showed broad peaks. It is proposed that oxyfluoride glasses and glass–ceramics based on the BaF2–Al2O3–B2O3 system have a high potential for optical device applications such as broadband optical amplifiers.

Prevalence of hepatitis- B virus infection among HIV patients in Ikole Ekiti, South – Western, Nigeria

Infections from HIV, Hepatitis B virus constitute a major public health challenge in sub-Saharan Afric a, and there are evidences to suggest that there is faster progr ession of HIV in those co-infected with either HBV. The aim of this study was to determine the prevalence of HBV infect ions among HIV-infected patients, and describe the sociodemographic features and correlates of HIV and HBV co-infected patients at Specialists Hospital, Ekiti , Nigeria. One hundred and fifty eight (158) HIV individuals w ho consented to the study were tested for HBV using Diaspot HBsAg kit (Screening test) and Biorex Diagnostic ELISA kit (Confirmatory test) between November 2012 and April, 2013. CD4 counts were also analysed with Aldrich Sigma kit and flow cytometery respectively. P value < 0.05 was considered to be significant. Prevalence r ates of Hepatitis B infections among HIV obtained w ere 5.7%. Individuals who were 51 years or younger were the most affected HBV co-infection was more common among females than males (3.8%: 1.8%, res, P = 0.0004). Out of 9 patients, 8 patients (88.9%) f ell within the age range 3049 years which implies the high prevalence of HIV a mong labour force while 1 patient (11.1%) fell with in the range of 50-60 years .Mean serum ALT and AST among participants with HIV alone were (42.0, 38.3) Internation al Units (IU), but were significantly higher (57.6, 43.7) In ternational Units (IU) for those with HIV/HBV co-in fection, P = (0.048, 0.032).Mean CD 4 count for HIV/HBV co-infected participants (389 ce ll/mm 3 ) was significantly higher than that for participants with HIV alone (230 cell /mm 3 ), P = 0.024 Conclusion: Co-infection with hepatitis B virus is common among HIV-infected patients in our setting and this further reaffirms the need for rou tine baseline screening for this marker, as it is a major conside ration in the initiation and choice of highly activ e antiretroviral therapy. Furthermore, those found to be negative sh ould be immunized with HBV vaccine to improve the prognosis of their HIV status.

Characterization of geopolymers from compositionally and physically different Class F fly ashes

The alkali-activation technology of coal fly ash is one of several potential solutions to minimize the harmful disposal of fly ash. This study reports high-resolution characterization of the alkali-activated reaction products for two representative Korean Class F fly ashes, which are significantly different in compositional and physical characteristics. The analysis confirms that differences in the network modifying element content, the amorphous phase content, and the particle size lead to large differences in compressive strength. Chabazite-Na and Al-rich chabazite-Na are identified as major crystalline phases in the high strength samples, supporting the favoring formation of ABC-6 family of zeolitic precursors for the higher mechanical strength while the C–S–H formation from the high CaO content (or crystalline CaO) is not a major source of the strength. The XRD analysis shows that the presence of amorphous humps located at 27–29° 2θ is not a sufficient indicator of geopolymeric gel formation. In the 29Si MAS NMR, some portion of −108ppm Q4(0Al) peak is not related to quartz, implying that this portion of Si atoms actively participate in geopolymerization. The 27Al MAS NMR spectra exhibit more conversion of Al(V) and Al(VI) aluminum atoms into Al(IV) units in the higher strength sample, which can be an indication of more geopolymeric reaction.