FeO Content Research Articles

Promotion of bio-oil production from the microwave pyrolysis of cow dung using pretreated red mud as a bifunctional additive: Parameter optimization, energy efficiency evaluation, and mechanism analysis

To address the issues of high oxygen content and energy consumption in the microwave-assisted pyrolysis of biomass for biofuel production, this study used high-temperature pretreated red mud (RM) as an additive. The pretreated RM exhibited dual functionalities, namely microwave absorption and catalytic properties, during the microwave-assisted pyrolysis of cow dung (CD). This study also evaluated the optimization potential of energy recovery efficiency. The results showed that the addition of pretreated RM significantly increased the oil yield during the microwave-assisted pyrolysis of CD. The highest oil yield (59.63%) was obtained via the microwave-assisted pyrolysis of CD over catalysis with RM pretreated at 750 °C (RM750). Through the optimization of the RM750-to-CD mixing ratio, optimal oil quality and energy recovery efficiency were achieved. At a mixing ratio of 1:1, the pyrolysis oil featured the highest aromatic hydrocarbon content and lowest acid content. The high-temperature pretreatment of RM increased the Fe2O3 content, which enhanced the dielectric properties and magnetic loss ability of the reactants. This resulted in localized high temperatures and the formation of “hot spots,” which can promote the deoxygenation and hydrogenation reactions of oil. Consequently, the lower heating rate of oil increased from 35.12 to 40.11 MJ kg−1. The released oxygen escaped in the form of CO. In addition, pyrolytic char was used as an in situ microwave absorbing material owing to its increased Fe2O3 content and graphitization degree, leading to an increase in energy recovery efficiency from 4.71% to 9.98%. This study provides valuable guidance for the efficient utilization of diversified solid wastes and demonstrates the potential application of microwave-assisted pyrolysis technology in the resource utilization of solid wastes.

A theoretical focus on nanoparticle attenuation capabilities for potential utilizations in radiation protect: TiO2-SiO2-Fe3O4-B4C-Al2O3

Radiation shielding materials are essential for various applications in space exploration, nuclear power plants, and medical devices. In this study, we present a theoretical design of radiation shielding nanocomposites based on a combination of TiO2-SiO2-Fe3O4-B4C-Al2O3 materials. Using the Phy-X/PSD, EpiXS, and XMuDAT programs, we calculated the radiation shielding properties, including mass attenuation coefficient, mean free path, and effective atomic number, of a series of nanocomposite structures with different Fe3O4 and B4C contents. Our results show that the addition of Fe3O4 and B4C to nanocomposites enhances the radiation shielding efficiency and the maximum shielding is observed in the nanocomposite with the highest density. The theoretical calculations also reveal that the proposed nanocomposites have excellent radiation shielding properties compared to conventional shielding materials, such as lead and concrete. This work demonstrates the potential of using a computational approach to design novel radiation shielding nanocomposites with improved performance, which could have significant implications for a wide range of applications.

Response of soil oxides in complex terrain region to environment revealed by hyperspectral observations

Soil oxides are important diagnostic indicators for soil quality assessment, and their content has a positive effect on adsorption of heavy metals, remediation of pollution, and enhancement of organic matter enrichment. Moreover, soil oxides are affected by multiple environmental factors such as soil pH, geomorphological, and elevation, and their distribution is highly regional. In this study, 421 ground soil samples and 2 hyperspectral satellite data were collected. The content distribution of 8 main oxides in soil, including SiO2, Al2O3, Fe2O3, MgO, CaO, Na2O, K2O, and Corg. were obtained according to the process of data preprocessing, spectral transformation, feature extraction, band combination, and model establishment. The results indicated that the homogenization spectral transformation method is the most suitable; The calculation accuracy of complex spectral characteristic parameters is inferior to that of characteristic bands; The difference model is more suitable for the extraction of soil oxide content in this study area; The average content of SiO2 and CaO shows a decreasing trend with the elevation increasing; The average content of SiO2 and Fe2O3 shows an upward trend with the increase of slope; East is the main geomorphic direction of soil oxide enrichment. SiO2, Al2O3, and MgO are the three soil oxides with the highest correlation. The response relationship between soil oxides, topography and pH is discussed, and the distribution rule of soil oxides and environmental determinants are obtained, which provides a set of technical schemes for digital soil research. This study can extract the content of soil components in a large area, analyze the causes, and provide a new technical scheme for soil investigation and treatment.

A novel method for CO2 injection direct smelting vanadium steel: Dephosphorization and vanadium retention

Abstract A novel method for CO2 injection direct smelting vanadium steel (CIDSVS) is proposed. Achieving selective oxidation of phosphorus is essential for the applicability of the suggested process. Under the guidance of thermodynamics, the mechanisms of CO2 injection dephosphorization and vanadium retention were investigated with CO2 flow rate and dephosphorization slag composition as experimental variables. The results indicate that CO2 as an oxygen source can remove 73.8% of phosphorus, while the oxidation rate of vanadium is 17.5%. The dephosphorization process can be divided into two stages: FeO- and CO2-dominated experimental processes. In the initial stage of slag feeding, [V] and [P] undergo fast oxidation, and the oxidation amount is positively correlated with the initial FeO content. The high basicity (CaO/SiO2 ratio) reduces the activity of V2O3 in the slag and promotes the oxidation of [V]. Under the experimental conditions of 1,400°C, the optimal conditions were determined to be a CO2 flow rate of 1.5 mL·g−1·min−1, a FeO content of 40%, and a basicity B of 2.5. Following the CIDSVS steelmaking operation, 80% of the vanadium is retained, and the impurity elements fulfill the specifications for steel. This method enhances vanadium utilization and is environmentally friendly.

ZIF-8 derived ZnFe2O4 nanoparticles as a high-performance anode material for lithium-ion batteries

ZnFe2O4 nanoparticles and ZnO/ZnFe2O4 composites were prepared by simple calcination of Fe2O3/ZIF-8. The bimetallic ZnFe2O4 not only inherit the high lithium storage capacity of Fe2O3, but also exhibit higher conductivity than that of single Fe or Zn oxides. The effect of Fe2O3 content in the raw materials on the structure and electrochemical performance of the product was discussed. Appropriate amount of Fe2O3 helps to obtain ZnFe2O4 nanoparticles with small size and porous structure, which can shorten the diffusion path of lithium ions, increase the contact area between the electrode material and electrolyte, thus improving the performance of the material. After 200 cycles at a current density of 300 mA g−1, the specific capacity can reach 1223.2 mAh/g. When the current density is increased to 2 A/g, the discharge specific capacity is retained at 809.4 mAh/g after 500 cycles.

Characterization of basaltic rock laterites in Dschang, West-Cameroon: Compressed Earth Bricks (CEB) for low-cost buildings

This study reports on the geotechnical characterization of lateritic soils upon basaltic rocks in Dschang, West-Cameroon. Six (06) soil samples from six (06) sites were taken for assessing their suitability in good quality CEB manufacturing. An analytical approach was adopted and consisted of standard physical and mechanical properties including water content, absolute density, Atterberg limits, grain size distribution and Optimum Proctor Modified (OPM). Mineralogical and geochemical contents of the materials were obtained by X-ray diffraction (XRD) and X-ray fluorescence (XRF) respectively. In addition, density, water absorption, abrasion resistance, and dry and wet compressive strengths were determined for manufactured brick specimens. Results indicate that the materials are rich in kaolinite (33–38%), gibbsite (21–27%) and goethite (22–26%) associated to low proportions of smectites (2–7%) and oxides such as hematite, ilmenite, anatase and bohmite. SiO2 (29.57–35.8%), Al2O3 (22.72–26.93%) and Fe2O3 (20.67–27.95%) are the most abundant oxides while basic cations are generally low in the materials (WIP: 2.25–5.89). The absolute density varies from 2.26 to 2.57 t/m3 and could be indicative of higher Fe2O3 contents. The plasticity index (7.80–18.95%) and the liquidity limit (57.80–64.50%) of materials allow their classification as inorganic silt and organic clay with high plasticity and compressibility that are not suitable for the production of CEB. Furthermore, these materials fall out the preferential plasticity domain recommended by Cameroonian standard for CEB. Based on grain size distribution, the studied materials also fall out the sprindle reference of the Cameroonian standard. For improving the characteristics of studied materials, a grain size correction was performed and provided an optimal mixture made up of 75% natural materials and 25% medium sand (0.05–0.5 mm) that is locally available. This is accompanied by considerable variations of consistency parameters allowing to pass from inorganic silt and organic clay to inorganic clay that display appropriate compressibility and plasticity for good quality CEB production. The using of cement at 4%, 6% and 8% revealed a progressive increase of the MDD (1.40–1.77%) and Wopt (12.60–28.39%). Moreover, the density and mechanical parameters of the manufactured specimens increase with the cement content. The density, physical and mechanical properties of the manufactured specimens fall within the Cameroonian standard of compressed earth bricks (CEB). Globally, the lateritic materials of Dschang improved with sand (25%) and Cement (8%) can be suitable for the production of good and low-cost CEB especially as the two additional materials are locally available and accessible.

Constructing a composite microfiltration carbon membrane by TiO2 and Fe2O3 for efficient separation of oil-water emulsions.

Membrane-based separation technology has attracted enormous attention for oil/water emulsion treatment. Here, composite microfiltration carbon membranes (MCMs) were prepared from the precursor of phenolic resin doping with TiO2 and Fe2O3 via the processes of stereotype and pyrolysis. The functional groups, thermal stability, porous structure, microstructure, morphology, and hydrophilicity of the membrane samples were analyzed by Fourier-transform infrared spectroscopy, thermogravimetric analysis, bubble pressure method, X-ray diffraction, scanning electron microscope, and water contact angle, respectively. The effect of dopant amount on the separation performance of MCMs was investigated. The results show that a mixed matrix system is constructed by TiO2 and Fe2O3 in MCMs, which is beneficial for further optimizing the pore size, porosity, and hydrophilicity of MCMs for oily wastewater treatment by varying the dopant amount. The maximum oil rejections are achieved at 98.9% and 99.6% for MCMs with a dopant content of TiO2 and Fe2O3 at 25%, respectively. In brief, this study offers an attractive strategy for improving the separation performance of MCMs for oily wastewater.

Growth of kyanite and Fe‐Mg chloritoid in Fe2O3‐rich high‐pressure–low‐temperature metapelites and metapsammites: A case study from the Massa Unit (Alpi Apuane, Italy)

AbstractChloritoid and kyanite coexist in metapelites from the high‐pressure/low‐temperature Massa Unit in the Alpi Apuane metamorphic complex (Northern Apennines, Italy). The composition of chloritoid is extremely variable throughout the Massa Unit. Fe‐chloritoid occurs in association with hematite‐free, graphite‐bearing schists, whereas strongly zoned Fe‐Mg chloritoid is found with hematite and kyanite. We investigated the effect of different bulk Fe2O3 contents in controlling chloritoid composition through phase equilibria modelling of four selected samples, representative of the different chloritoid‐bearing parageneses found in the Massa Unit. The ferric iron content, measured through wet chemical titration, ranges from 0 (graphite‐chloritoid schist) to 73% of the total iron (hematite‐chloritoid schist). We show that Mg‐rich chloritoid compositions and stability of kyanite at greenschist to blueschist facies conditions can be reproduced in the MnO–Na2O–K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–O (MnNKFMASHTO) chemical system only considering the presence of significant amounts of ferric iron as part of the bulk composition. The stabilization of kyanite at lower grade is directly linked to the presence of Fe2O3, which renders the reactive bulk rock composition effectively enriched in Al2O3 with respect to Fe and Mg. We also document that high Fe2O3 contents exacerbate the effect of chloritoid fractionation, producing strongly zoned Fe‐Mg‐chloritoid grains. Finally, the P–T modelling of the Massa Units performed in this study allows, for the first time, the recognition of a two‐stage evolution at peak conditions, with an earlier pressure peak (1.2–1.3 GPa at 350–400°C), and a later thermal peak (0.7–1.1 GPa at 440–480°C), compatible with subduction, underthrusting and exhumation of the Adria continental margin during growth of the Northern Apennine orogenic wedge.

Barred olivine chondrules in ordinary chondrites: Constraints on chondrule formation

AbstractIn general, barred olivine (BO) chondrules formed from completely melted precursors. Among BO chondrules in unequilibrated ordinary chondrites, there are significant positive correlations among chondrule diameter, bar thickness, and rim thickness. In the nebula, smaller BO precursor droplets cooled faster than larger droplets (due to their higher surface area/volume ratios) and grew thinner bars and rims. There is a bimodal distribution in the olivine FeO content in BO chondrules, with a hiatus between 11 and 19 wt% FeO. The ratio of (FeO rich)/(FeO poor) BO chondrules decreases from 12.0 in H to 1.6 in L to 1.3 in LL. This is the opposite of the case for porphyritic chondrules: the mean (FeO rich)/(FeO poor) modal ratio increases from 0.8 in H to 1.8 in L to 2.8 in LL. During H chondrite agglomeration, most precursor dustballs were small with low bulk FeO/(FeO + MgO) ratios and moderately high melting temperatures. The energy available for chondrule melting from flash heating was relatively low, capable of completely melting many ferroan dusty precursors (to form FeO‐rich BO chondrules), but incapable of completely melting many magnesian dusty precursors (to form FeO‐poor BO chondrules). When L and LL chondrites agglomerated somewhat later, significant proportions of precursor dustballs were relatively large and had moderately high bulk FeO/(FeO + MgO) ratios. The energy available from flash heating was higher, capable of completely melting higher proportions of magnesian dusty precursors to form FeO‐poor BO chondrules. These differences may have resulted from an increase in the amplitude of lightning discharges in the nebula caused by enhanced charge separation.

Green Synthesis of Fe3O4 Nanoparticles Using Green Betel Leaf Extract for Methylene Blue Adsorption

Abstract The synthesis of Fe3O4 nanoparticles has become a matter of interest because it has properties and useful applications in various fields. Using plant extracts using the green synthesis method to manufacture Fe3O4 nanoparticles is considered an effective, efficient, and environmentally friendly approach because it does not contain harmful chemicals. This study uses the green synthesis method to synthesize Fe3O4 nanoparticles from green betel leaf extract. The UV-Vis Fe3O4 nanoparticles showed continuous absorption at wavelengths between 300 nm and 800 nm and obtained a band gap energy of 1.87 eV. XRD analysis confirmed the crystal size of Fe3O4 nanoparticles (≈ 6.93 nm). The FTIR results show that functional groups from the leaf extract play a role in forming Fe3O4 nanoparticles, as evidenced by the presence of two Fe-O absorption bands at wave numbers 567 cm-1 and 482 cm-1. The SEM results showed a needle-like particle shape, the HR-TEM analysis showed spherical and needle-like shapes and nanoparticles size (≈ 29.82 nm) and the EDS analysis showed that Fe and O elements indicated the dominant iron oxide content of Fe3O4 with levels of 73.35% and 20.88%, respectively. The magnetization curve shows that the green synthesized magnetite has ferromagnetic properties. The ferromagnetic properties of Fe3O4 were then applied as methylene blue adsorbent and observed using UV-Vis spectroscopy, the most effective absorption ability was at a contact time of 120 minutes with a color degradation percentage of 98.75%. Keywords: Green synthesis, Fe3O4, Green betel, Adsorption, Methylene blue

Evolution of Interface Characteristic between Quicklime and CaO–SiO2–FetO–MgO Melt during Slag‐Forming Procedure in Converter under Different Times

In 2022, China produced 1.018 billion tons of crude steel, with steel slag accounting for 10–15% of the output. The presence of 10–20% f‐CaO in steel slag causes volume instability, hindering comprehensive utilization. The generation of f‐CaO is closely associated with the dissolution of quicklime during the converter slag‐forming procedure. This study focuses on investigating the evolution of the lime–slag interface and the variations in lime dissolution rate under different slag conditions using the electron probe microanalyzer and ImageJ. The results reveal that the formation of the CaO–FeO solid solution, (Ca, Mg, Fe) olivine, and low‐melting point (Ca, Mg) olivine at 1400 °C. As the FeO content decreases, a dense and high‐melting‐point 2CaO·SiO2 layer is formed. A maximum thickness of the 2CaO·SiO2 layer is precipitated at a dissolution time of 180 s. Additionally, the average dissolution rate of lime in different slags shows an initial increase followed by a subsequent decrease. Among the slag studied, the highest average dissolution rate is in slag A3 at 2.24 × 10−6 m s−1, while the lowest rate is in slag A4 at 1.49 × 10−6 m s−1. The presence of the 2CaO·SiO2 layer hinders the mass transfer, thereby further inhibiting the reaction.

Analysing the HIsmelt process for smelting vanadium–titanium magnetite

ABSTRACT In response to the problem of rich vanadium–titanium magnetite (VTM) resources in China contrasting with low blast furnace utilization, a HIsmelt process for smelting VTM is proposed. The influence of the process parameters on smelting reduction is analysed under laboratory conditions by simulating smelting reduction. The results show that extending the reaction time reduces the FeO content in the slag by 15.34 wt-%, increasing the reaction temperature reduces the FeO content in the slag by 26.38 wt-%, and increasing the basicity reduces the FeO content in the slag by 11.26 wt-%. The control temperature for smelting VTM using the HIsmelt process is 1425°C, with a reduction time of 20–30 min, which is conducive to the transfer of vanadium to the molten iron and the enrichment of titanium in the slag. To ensure vanadium and titanium are efficiently utilized, a basicity control of 0.8 is appropriate.

Mineral resource base of Kazakhstan for the production of window glass

The chemical compositions of natural and man-made raw materials of Kazakhstan: quartz sand, quartzite, aluminum, calcium and alkali-containing components used in the production of window glass are investigated. According to the chemical composition, all quartz sand deposits meet the requirements of GOST, except for the content of iron oxide. To use quartz sands in the production of flat glass, it is necessary to enrich them. Chemical compositions of feldspar, quartz-feldspar, pegmatite, kaolin have been studied. Deposits of high-quality feldspar raw materials have been found in the Khantau, Maikul deposits (Zhambyl region), in Kostanay (Bisembaevskoye and Marinskoye pegmatite deposits) and Akmola regions (Zerendinskoye field). Alekseyevsky kaolin is of interest, with a high content of aluminum oxide (38.2 %) and a low content of iron oxide. There are quite large reserves of limestones and dolomites in the Republic of Kazakhstan, including the Karatau, Talgar and Shieli deposits. Reserves of chalk with a calcium carbonate content of 94-98 % and insignificant iron oxide are available in the Mangistau region. Kazakhstan has deposits of natural sodium sulfate in the form of solid deposits and brine of numerous lakes. The phase composition of local quartz sands and feldspar has been studied by X-ray phase analysis. Compositions have been developed and experimental glass cooking has been carried out. The content of silicon oxide as the main component in the initial quartz sand is 99.1 %, and the coloring glass of iron oxide is 0.08 %. Therefore, the enrichment method was used to reduce the content of iron oxide in the sand.Studies have shown that magnetic separation can reduce the Fe2O3 content from 0.08 to 0.06 %, by washing from 0.08 to 0.05 %, by flotation to 0.03 %. The size of quartz sand is within the limits that do not complicate the glass cooking process:the content of large grains larger than 0.8 mm is 0.3 %, small grains smaller than 0.1 mm -3 %. The mass fraction of the heavy fraction with a density of more than 2900 kg/m3 is -0.2%. According to complex indicators, the sand corresponds to the VS-030-1po GOST 22551-90 brand. The characteristic intervals of changes in the viscosity of cooking, production, molding, annealing and the corresponding temperatures are determined. The values of the physico-chemical and technological properties of the glasses were obtained by the calculation method. A schedule of annealing of flat glass has been developed.

Tomographic Imaging of Bauxite Grains Leached Using Hydrochloric Acid

X-ray computer tomography (XRT) is a three-dimensional, nondestructive, and thus reproducible examination method that allows for the investigation of internal and external structures of objects. Due to its characteristics, the XRT technique has increasingly established itself as an alternative examination method and is also applied in the field of mineral processing. Within this work, XRT is used to investigate the influence of hydrochloric acid leaching of iron-rich bauxites on grain composition. Acid leaching is a promising method for the beneficiation of iron-rich bauxites for refractories. Many studies have already established that leaching with hydrochloric acid can reduce the Fe2O3 content in bauxites. However, apart from the influence of the leaching process on the composition of the bauxites, aspects such as the influence of the acid on the exact grain constitution or the porosity behavior have rarely been considered so far. To address these open questions, XRT analysis was used to examine and characterize various bauxites. By comparing identical grains before and after leaching, it was observed that in gibbsite bauxites the acid penetration is deeper, and the volume decreases significantly. In diasporic and boehmitic bauxites, clear leaching edges can be seen in which the iron content has been reduced.

Properties of liquid CaO–SiO2 and CaO–SiO2-‘Fe2O3’tot slags measured by a combination of maximum bubble pressure and rotating bob methods

Liquid slag properties are essential for understanding complex mass and momentum phenomena in metallurgical operations. The density, surface tension and viscosity were measured in six silicate-rich slags of the CaO–SiO2 and CaO–SiO2-‘Fe2O3’tot systems by combining the maximum bubble pressure and rotating bob methods. The properties investigated were sensitive to the temperature, SiO2 and Fe2O3 contents. Different experimental trends were derived due to the amphoteric properties of Fe2O3. The slags with ferric oxide were denser than the silicate melts. Surface tension gradually decreased with temperature and indicated firstly a rise and then decline with further Fe2O3 addition. Raman spectra were analyzed to provide structural information of the polymer melt and indicated an enhancement in the polymerization degree with Fe3+. The derived experimental trends and role of Fe3+ in the silicates were attributed to the interplay of complex factors: different bonding in the melt, cation interactions and the oxidation state of iron. The influence of Fe3+/Fe2+ on the melt properties was discussed.

Towards performance-based specifications for fly ash and natural pozzolans – Insights from a Monte-Carlo based thermodynamic modeling framework

Monte-Carlo-based thermodynamic modeling framework is used to assess the chemical limits set by ASTM C618-23. Realistic chemistries and reactivities for supplementary cementitious materials (SCMs) and chemistries for cement are generated using statistical data from the literature. 200,000 thermodynamic simulations are performed for each cement+SCM system to evaluate performance through Ca(OH)2 content, capillary porosity, and C-S-H volume. The results indicate that the reactivity of SCMs is directly related to its performance in paste, and its inclusion in ASTM C618 would be beneficial for optimized utilization of SCMs in performance-based mixtures. When providing chemical limits for SCMs, separating the reactive pozzolanic oxides (RPO) from bulk oxide composition is critical for paste performance. Fe2O3 content did not significantly impact the performance. If RPO is specified, fly ashes and natural pozzolans could have similar chemical limits. SCMs can be classified based on CaO and SO3 contents to affect Ca(OH)2 and AFt in paste, respectively.

Optimizing fluidity and tensile strength of magnetically driven epoxy-cement repair materials based on response surface

Underwater crack repair is challenging due to drainage and exhaust, slurry retention at fixed points, and other issues. Magnetically driven epoxy resin cement slurry was developed, which can perform directional movement and fixed-point retention of slurry under the effect of an applied magnetic field. This paper focuses on slurry fluidity and tensile properties. Firstly, in the preliminary pre-study, the main influencing factors of the ratios were determined. Then, the optimum range of each factor is determined by a single-factor experiment. Furthermore, the response surface method (RSM) is applied to obtain an optimal ratio. Finally, the slurry is characterized by micro. Results showed that the evaluation index F proposed in this paper can well evaluate the interaction between fluidity (X) and tensile strength (Y). The 2FI regression model and the quadratic regression model are developed with fluidity and tensile strength as the response values and Epoxy Resin (ER) content, water-cement ratio, Fe3O4 content and sulphoaluminate cement (SAC) content as the influencing factors, and have reasonable fit and reliability. The relationship between the degree of influence of the influencing factors on the response value X and the response value Y in ascending order was: ER content > water-cement ratio > SAC content > Fe3O4 content. The magnetically driven slurry made by the optimal ratio can reach a fluidity rate of 223.31 mm and a tensile strength of 2.47 MPa. This is with relative errors of 0.36% and 1.65% from the model predicted values. Microscopic analysis showed that the magnetically driven epoxy resin cement slurry had a favorable crystalline phase, surface morphology, and structural composition.

Study on volatilization behaviour of BOF converter slag containing CaCl2

ABSTRACT The volatilization behaviour of CaCl2-containing basic oxygen furnace (BOF) slags was investigated in laboratory at steelmaking temperature. During the melting process, the volatilization ratio was measured, and the volatile compounds were collected with some conductive tapes. Thermogravimetric analysis was conducted to clarify the volatilization of CaCl2-containing slags, and the volatilization ratio was also calculated by the thermodynamic software HSC. It was found that volatilization takes place in both CaCl2-containing and CaF2-containing BOF slags, but their influential mechanisms are different. FeCl2 is the main volatile compound in CaCl2-containing BOF slags. The increasing contents of CaCl2 and FeO in these slags are favourable for volatilization, while higher slag basicity plays the opposite role. In the case of CaF2-containing BOF slags, the volatilization compounds have little relation to the FeO content in the slags, and the volatilization ratio is smaller than that of CaCl2-containing BOF slag.

Study of the Mineralogical and Chemical Compositions of the Weakly Magnetic Fractions of the Egyptian Black Sand Altered Ilmenite

One of the most extensively studied topics in dozens of studies is the alteration process of ilmenite, the formation of leucoxene, and the presence of some impurity oxides: SiO2 and Al2O3. The altered Egyptian black sand ilmenite grains of relatively lower magnetic characters are studied using the binocular microscope and the Cameca SX-100 microprobe instrument. Both individual brown- and black-altered grains separated at 0.5 and 1 ampere values are investigated. The detection of the various alteration phases, their molecular formulas and limits, and the role of SiO2 and Al2O3 in alteration mechanisms are detected. The alteration phases include pseudorutile (psr) and leached pseudorutile (lpsr) of different phases in addition to rutile. Few analyzed spots are detected to be leached ilmenite (lilm). Several Excel software are adopted to calculate the chemical formulas of each alteration phase. The contents of TiO2 and Fe2O3 of all the investigated psr/lpsr in the study are in the range of 59.16–86.56% and 37.3–6.68%, respectively. The Ti/(Ti + Fe) ratio for these formulas ranges between 0.60 and 0.88. The psr/lpsr chemical formulas of all the investigated grains range as follows: Fe2.01-0.50Ti3O8.97-4.50(OH)0.03-4.50. The concluded lowest cationic iron content of the well-defined accepted lpsr phase is 0.5 with a corresponding molecular formula of Fe0.50Ti3O4.5(OH)4.5. The results revealed that in the region of 68–70 TiO2%, the mechanism of ilmenite alteration may be changed where neither all the analyzed TiO2 of the spot nor all the calculated structural water are contained within the molecular formula of lpsr. There are other associated mineral phases containing some TiO2 and also some structural water which most probably are removed from the lpsr phase. As the analyzed spots are located at highly fissured locations, the alteration process is relatively faster and the lpsr phase can be broken into rutile and hematite. Additionally, as the analyzed TiO2 and structural and/or molecular water contents increase, the darkness of the BSE image areas of the grain increases; this may reflect the existence of an individual TiO2 phase, most probably rutile, mixed in homogeneity with the existed lpsr component. As the content of TiO2 increases, within a definite TiO2 range (80–85%), the associated contents of Al2O3 and SiO2 increase. When the contents of the structural and/or molecular water contained within the lpsr phases decreases, the total oxides sum is more than 98%, the contents of Al2O3 are highly depleted. In the late alteration stages, the lpsr structure does not suddenly collapse but gradually produces other associated mineral phases. The relatively enriched contents of SiO2 and/or Al2O3 in some secondary rutile grains can be explained as most of the SiO2% is associated with mol water or bearing for mol and/or str water necessary for the leachability of Fe3+ from the psr structure. The XRD patterns of the investigated grains before and after roasting at 1100 °C for one hour are detected and interpreted.

Excellent microwave absorption performance of LaFeO3/Fe3O4/C perovskite composites with optimized structure and impedance matching

Compositional optimization and structural design are considered to be effective approaches for improving the microwave absorption (MA) ability of carbon-based absorbers. Herein, we have synthesized the LaFeO3/Fe3O4/C perovskite composites by one-step pyrolysis of 3d-4f metal-organic frameworks (MOFs) at a low temperature. The content of LaFeO3 and Fe3O4 can be efficiently controlled by tuning the pyrolysis temperature. For LaFe-MOF-650 composite, the effective absorption bandwidth (EAB, RLmin ≤ −10 dB) reaches 7.2 GHz at 2.2 mm under a filling ratio of 50 wt%. Further, the effect of hollow and spiral carbon on the MA performance of 3d-4f-MOFs-derived composites is investigated. The minimum reflection loss (RLmin) of the hollow LaFeO3/Fe3O4/C sample with a thickness of 1.82 mm reaches up to −68.3 dB under a filling ratio of 40 wt%. The spiral LaFeO3/Fe3O4/C sample exhibits an RLmin of −42.3 dB and an EAB of 4.70 GHz at an ultra-low thickness of 1.35 mm under a lower filling ratio of 30 wt%. Benefiting from the structural and compositional advantages, the prepared high-efficiency MA materials with optimized impedance matching and attenuation capability are excellent candidates for high-performance MA materials.