Hematite Powder Research Articles

Radiation shielding properties of sustainable concrete with novel plastering techniques

In concrete applications. Major/critical applications of such concrete are radiation-shielding facilities. Both steel slag and silica fume are examples of common by-product materials that can be used as a replacer of aggregates and cement. Thus, in this research work, steel slag was utilized as heavy aggregate in concrete production besides silica fume to present sustainable concrete mixtures probably with better radiation-shielding properties. Different cementitious plasters were applied on the conducted sustainable concrete mixture using different powdery materials; hematite, magnetite, barite, bentonite, and steel slag powders in addition to nano-titanium dioxide as full replacers for sand. The proposed plasters were presented to determine the optimum plaster technique in terms of static performance and attenuation capability against gamma and neutron radiations. The results exhibited that utilizing steel slag and silica fume in concrete mixtures enhanced compressive strength by up to 9.09 % compared to conventional concrete, while the addition of nano-titanium to conventional plaster led to superior enhancement in the compressive strength by up to 38.65 % relative to traditional plaster. Conversely, fully replacing conventional silica sand with the abovementioned powdery materials generally reduced the compressive strength of cementitious plasters by up to 30.83 %. However, the radiation shielding properties against Cs-137, and Co-60 energies have been enhanced by up to 20 % and 26 %, respectively.

Seaweed assisted preparation of Fe2O3 nanoparticles and their antiviral studies against White Spot Syndrome Virus (WSSV): In vitro and in silico approach.

In the present study, preparation of Fe2O3 nanoparticles using seaweed Sargassum swartzii extract and characterized using XRD, FTIR, and FE-SEM with EDAX analysis. The crystalline nature of γ-Fe2O3 nanoparticles (hematite powders) were confirmed using XRD. In FT-IR spectra of the Fe2O3 nanoparticles, the major bands at 594 cm−1 and 461 cm−1 observed correspond to the metal‑oxygen (FeO) vibrational modes. The surface morphology of Fe2O3 nanoparticles has been studied by FE-SEM. In vitro toxicity and anti-WSSV activity of Fe2O3 nanoparticles were carried out using the shrimp-insect hybrid cell line (PmLyo-Sf9). The bioactivity of Fe2O3 nanoparticles against the WSSV infected with the PmLyo-SF9 cell line was analyzed through dose-dependent attachment inhibition and virucidal activity at an optimum concentration of 320 μg/mL and confirmed by the expression of viral envelope protein VP28. Further, the computational approach of VP28 envelope protein and Fe2O3 binding affinity was confirmed using molecular docking studies. Hence, the Fe2O3 nanoparticles can be formulated as an anti-viral agent against the aquaculture pathogens in efficient disease control.

Sol–gel synthesis of manganese-doped n-type hematite powder photocatalyst supported on g-C3N4 sheets for the degradation of organic dyes

Sol–gel synthesis of manganese-doped n-type hematite powder photocatalyst supported on g-C3N4 sheets for the degradation of organic dyes

Microstructure and Compressive Strength of Geopolymer Materials Based on Metakaolin with Hematite and Magnetite Gels as Additives

The purpose of this work is to increase the compressive strength and improve the microstructure of geopolymer materials by adding hematite and magnetite gels, as well as their powders, cured at 80 °C. Hematite and magnetite are dissolved in 10 M sodium hydroxide. Dried gels of hematite and magnetite were then ground to produce powders of dissolved hematite and magnetite. For the production of various geopolymer materials, the metakaolin was replaced by 0 and 10 wt. % of each additive and then mixed with the hardener containing the SiO2/Na2O molar ratio set at 1.6. The results show that the reference geopolymer has a compressive strength of 51.11 MPa. These values are 50.99 and 47.59 MPa for the geopolymer materials with 10 wt. % of dissolved magnetite gel and the powder of dissolved magnetite cured at 80 °C, respectively. They are 59.52 and 63.23 MPa for those prepared using 10 wt. % of dissolved hematite gel and for the powder of dissolved hematite cured at 80 °C, respectively. Si, Al, Fe, Na and Ti form a homogeneous phase in the geopolymer structures with the exception of a few magnetite particles agglomerated in the geopolymer materials. Compressive strength was found to be improved by the use of hematite gel and dissolved hematite powder cured at 80 °C as additives. A slight reduction in the compressive strength was observed when the dissolved magnetite gel and the powder of the dissolved magnetite cured at 80 °C were used as additives.

Reduction kinetics of hematite powder using argon/hydrogen plasma with prospects for near net shaping of sustainable iron

Direct reduction of iron ore using hydrogen plasma is being explored as a potential solution to decarbonize the iron and steel sector. The current state-of-the-art demonstrated reduction of hematite pellets via hydrogen plasma using Ar + 10% H2 but had slow reduction kinetics, requiring 30 minutes of plasma exposure for complete reduction. Here we show that using hematite in a powder form, easily obtainable from beneficiated ore, results in 10× faster kinetics using plasma generated from Ar + 2% H2 shielding gas compared to the current state-of-the art. The increased kinetics using powders and a dilute hydrogen concentration can enable the use of advanced manufacturing techniques like blown powder directed energy deposition using a plasma tungsten arc welding torch to manufacture near net shape components directly from the ore concentrates. This ore to part approach will also reduce the emissions associated with downstream processes like rolling, forging, and machining, thereby further aiding in the sectorial decarbonization efforts.

On the formation of dendritic iron from alkaline electrochemical reduction of iron oxide prepared for metal fuel applications

Low-temperature electrochemical reduction (electroreduction) of iron oxides is a promising alternative to the conventional methods for iron production due to its CO2-free operation and relatively low energy consumption. In this work, we demonstrate a novel approach for electrochemical iron production by promoting the formation of dendritic structures during iron electrodeposition, which facilitates the easy harvesting of deposits in powder form. Experiments were conducted using a single pair of parallel plate electrodes, immersed in a mixture of hematite (Fe2O3) powder and aqueous alkaline (NaOH) slurry. The effects of current density, Fe2O3 mass fraction, temperature, and powder size on current efficiency and deposit morphology are investigated. A large quantity of dendritic iron structures is observed when experiments are carried out without stirring and/or applying heat from a heating plate. This condition suggests temperature and (ion/species) concentration gradients in the system. The dendrites are mainly deposited on the cathode's sides, corners, and edges. Different deposits and dendritic structures (compact layer deposit, moss-like deposit, deposit with whisker-like dendrites, and deposit with crystal-like dendrites) are observed as operating conditions change. Overall, a cathodic deposition of metallic iron with a high Faradaic efficiency (≥90 %) is successfully accomplished. The present findings provide new insights into the production of electrolytic iron powder and its future use as a carbon neutral and sustainable fuel/energy carrier.

Reduction Kinectics of Hematite Powders in Non-Equilibrium Hydrogen Plasma

Reduction Kinectics of Hematite Powders in Non-Equilibrium Hydrogen Plasma

Static and dynamic performance of different concrete mixtures for the protection of aircraft shelters

Concrete is the most significant construction material in the world. However, extreme static and dynamic loads placed on infrastructure in recent decades have led to structurally catastrophic disasters. In addition, recent weapons can significantly impact the safety of humans and infrastructures. Newly developed concrete shields are designed to protect against severe loading conditions such as impact loads. Therefore, due to the rapid progress in weapons production, such as projectiles and bombs, there is a critical need to protect aviation buildings and aircraft shelters from such destructive impacts. In this study, the static and dynamic performance of concrete shields produced by nationally available magnetite, hematite, graphite, steel fibers, and steel mesh constituents were evaluated. Test results showed that implementing graphite, hematite, and magnetite powder in concrete shelters’ production slightly decreased the static behaviour of produced mixtures. On the other hand, superior impact resistance was achieved by incorporating steel fibers and steel mesh in aircraft concrete shields.

The Production of Hematite Powder from Spent Pickling Hydrochloric Acid

This research aimed to study the recycling process and the feasibility of recovering iron as hematite or red oxide powder (Fe2O3) from spent pickling acid (hydrochloric acid). The spent hydrochloric acid waste from the pickling bath in the sheet rolling steel industry contains approximately 233 g of iron dissolved in one liter of the spent acid. To recover iron, 2 M NaOH was added to the spent acid until reaching pH 7. The iron was precipitated as iron oxide and/or hydroxide. Next, the oxidation of ferrous oxide was carried out by adding H2O2 35%v/v to control the shade color. The precipitates were subsequently separated from the acid solution by a filter press. The precipitates were dried at 110°C for 24 h and calcined at 700°C for 2 h to synthesize and modify the crystallinity of ferric oxide. Ferric oxide was subject to water washing, where contaminating sodium chloride could be dissolved and filtered out. After drying at 110°C for 24 h, high-purity hematite was achieved. Hematite recovered from the spent pickling acid via this process provided more than 97% purity at 94.4% recovery.

Dry powders reflectance model based on enhanced backscattering: case of hematiteα-Fe2O3.

By performing bidirectionnal reflectance distribution function (BRDF) measurements, we have identified backscattering as the main phenomenon involved in the appearance of dry nanocrystallized powders. We introduce an analytical and physically based BRDF model that relies on the enhanced backscattering theory to accurately reproduce BRDF measurements. These experimental data were performed on optically thick layers of dry powders with various grains' morphologies. Our results are significantly better than those obtained with previous models. Our model has been validated against the BRDF measurements of multiple synthesized nanocrystallized and monodisperse α-F e 2 O 3 hematite powders. Finally, we discuss the ability of our model to be extended to other materials or more complex powder morphologies.

Comparative study of electroreduction of iron oxide using acidic and alkaline electrolytes for sustainable iron production

Sustainable iron production is largely driven by the urgency to reduce the extensive energy consumption and emissions in the iron/steel sectors. Low-temperature electroreduction of iron oxide technology is thus revived since it directly utilizes (green) electrical energy with a competitive energy consumption compared to the thermochemical reduction approach. In the present work, we perform theoretical and experimental studies for comparison of electroreduction of iron oxide in aqueous alkaline and acidic electrolytes. Electrochemical reduction and deposition behavior are experimentally investigated using a lab-scale cell containing an electrolyte suspended with micron-sized Fe2O3 (hematite) powders. The effects of current density and hematite mass fraction on current efficiency are evaluated, as well as the total energy consumption. Results of chrono-potentiometry and cyclic voltammograms (CV) reveal the electrochemical properties of each system. The CV's cathodic peaks, corresponding to the reduction of iron oxides to iron, are observed only in the alkaline system where the iron oxide can be reduced at about −1.4 V (vs. Ag/AgCl). It is also found that the alkaline system has higher current efficiency (25–30% higher) and lower energy consumption (∼30% lower) than the acidic system. The cleaning of the deposit is also easier for the alkaline system, resulting in an iron product of high purity. Concerning the electrochemical performances and practicality, the alkaline electroreduction system shows promising potential for sustainable iron production.

Improving the resistance of ultra-high-performance concrete against nuclear radiation: Replacing cement with barite, hematite, and lead powder

Ultra-high-performance concrete (UHPC) is concrete with a high cement content; thus, replacing the cement with other materials can contribute to the sustainable production of UHPC. This type of concrete offers desirable strength characteristics and durability, which makes it a possible deterrent for countering gamma rays. The addition of sustainable materials can reduce the thickness of the protective concrete structures and possibly provide the desired attenuation and half-life coefficients. The current study used barite, hematite, and lead powders as replacements for cement at contents of 10%, 15%, 20%, 25%, and 30%. Compressive and flexural strength tests were performed at 28 days of age and X-ray diffraction (XRD) tests at 180 days of age. To determine the radiation attenuation and half-life coefficients, sodium iodide crystals were used with a gamma-ray spectrometer from three sources (137Cs, 60Co, and 207Bi) at energies of 662, 1173, and 1333 keV. The results showed that the replacement of cement with barite and hematite powder at all percentages reduced the compressive and flexural strengths of the concrete. Their highest compressive strengths were at 10% cement content (106 and 109 MPa, respectively). Replacement of cement with 20% lead powder provided the maximum compressive and flexural strengths of 129 and 13.5 MPa, respectively. XRD analysis showed that the reason for the high compressive strength with 20% lead powder was the increase in the resistance phases and the decrease in ettringite. The highest attenuation and lowest half-life coefficients were for UHPC with 30% lead powder (0.23 cm-1 and 3 cm, respectively). This was about 53% higher than that of the UHPC-only sample, and its half-life coefficient was 35% lower. Therefore, UHPC with 30% lead powder was the most efficacious mix design for resistance to gamma rays.

Annealing Temperature Dependent of the Structural and Magnetic Properties in Hematite Prepared by Sol-Gel Method

The annealing temperature dependent on the structural and magnetic properties of hematite (α-Fe2O3) powders synthesized via the sol-gel method was studied. The sol-gel method is used to prepare nanoparticles for this experiment. The annealing treatment of 200°C, 400°C, 600°C, and 800°C has been carried out to modify the physical properties. The obtained nanoparticles are characterized by their structural properties using X-ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. Then, magnetic properties were evaluated using Vibrating Sample Magnetometer (VSM). XRD results have shown an increase in crystallite size with an increase in annealing temperature from 35.10 nm to 60.17 nm. The increase in crystallite size can be attributed to the increase in the crystal structure’s internal energy, which promotes atomic diffusion. The FTIR results show an absorption that appears at the peak around ~530 cm-1. It indicates that the Fe3+ cation has successfully formed. The VSM results show an increase in the value of Hc with an increase in the annealing temperature from 117 Oe to 461.5 Oe. It is supported by the increase of anisotropy constant and increasing temperature annealing.

Effect of water vapor on the reduction kinetics of hematite powder by hydrogen-water vapor in different stages

The powder of the hematite sample was isothermally reduced with a hydrogen-water vapor gas mixture at 1023K-1273K. The results indicate that the overall reduction process of hematite can be divided into three stages (Fe2O3-Fe3O4-FeO-Fe) each of which should be investigated. At 1023K, the average reaction rate decreased by 53.6% in stage 1 when the water vapor content of the reaction gas increased from 0% to 50%, and it decreased by about 77.2% in stage 2. However, in stage 3, when the water vapor content increased only from 0% to 20%, it decreased by about 78.1%. The results also show that the influence of water vapor on the reduction reaction increases with increasing reaction temperature in all stages of the reduction reaction. The microstructure of the reduction products showed that they still had some holes; that did not seriously block the channel for hydrogen diffusion. Various models were considered to further clarify the influence of water vapor in the reduction stage The range of apparent activation energy of the different stages obtained by the model fitting was about 20-70 kJ/mol, which also confirmed the absence of the solid-state diffusion phenomenon.

The effect of cross-linker structure on interfacial interactions, polymer dynamics and network composition in an epoxy-amine resin

Understanding interactions at the polymer / metal oxide interface is central to improving the performance lifetime of corrosion resistant coatings, where network polymers commonly form via step growth mechanisms in the presence of pigments. Here we employ a holistic analytical approach encompassing ATR-FTIR, DSC and molecular dynamics simulations to consider how crosslinker structure affects adsorption and incorporation into the network, using a stoichiometric mixture of diglycidylether of bisphenol-A (DGEBA) with m-xylylenediamine (MXDA) cured in the presence of hematite (Fe2O3) and goethite (FeOOH) powders. We find that the rigid MXDA molecule has two distinct binding modes on both hematite and goethite, and that synergistic hydrogen bonding modes observed on goethite limit interconversion between the two. Moreover, we find that binding persists in fully cured composite samples, determining the levels of residual amine. In contrast to previously reported results using triethylenetetramine (TETA) crosslinkers, however, we find that the Tg of composite specimens is independent of added hematite and goethite volumes. Molecular dynamics simulations demonstrate this is due to electrostatic binding between the cationic Fe sites and electronegative heteroatoms in MXDA. This renders both amine functionalities unavailable for incorporation into the network and hence, unlike TETA, MXDA adsorption does not determine polymer dynamics.

Microstructural analysis of iron ore samples with bitumen as a binder

In the present investigation, the direct reduction of magnetite and hematite powder with and without 5% bitumen at various temperatures has been studied in a hydrogen atmosphere. The prepared samples were fired in the temperature range of 673–1373 K to observe the weight loss and to find the effect of the bitumen in the samples. The microstructural results show that bitumen mixed with iron ore powder exhibited a more porous structure with cracks after reduction at 773 K and 973 K respectively. At temperatures above 1073 K, the carbon present in bitumen contributed to an enhanced rate of reduction of iron oxide samples. It was observed that, the reactivity of samples was affected by the level of impurities, crystal structure, binder, and composition of the reducing agent.Graphical

A new method of full resource utilization of copper slag

Copper slags can hardly be utilized because the fayalite in it produces silica gel during the dissolution process. This work proposes a new process on sulfuric acid treatment of copper slag (Jinchuan Group, Gansu Province, China.). The results show that over 98% of recovery efficiency of Cu2+, Co2+, Ni2+ and Zn2+ was achieved through the whole process cycle. Ammonia was used to control the pH of the solution in order to completely precipitate Fe2+, and then produce hematite powder. More than 85% of the non-ferrous metal ions were left in the solution, and the utilization method of stepwise extraction was evaluated. The generation of silica gel during the acid digestion of copper slag was not restricted, and the silica gel in the acid-leach residue was subsequently dissolved with NaOH solution to obtain sodium metasilicate solution. Acidification and other steps were carried out to produce high-purity silica with a purity of 99.9%. Magnetite and pyroxene were obtained by using a simple magnetic separation process to segregate the remaining slag phase. The whole process achieves the full resource utilization of copper slag, and exhibits great potential for the future industrial utilization of copper slag in an economically and environmentally friendly way.

Dissolution of Magnetite and Hematite in Mixtures of Oxalic and Nitric Acid: Mechanisms and Kinetics

Dissolution mechanisms and kinetics have a key role in better understanding of processes. In this work, magnetite and hematite powder were dissolved in oxalic and nitric acid mixtures at different temperatures. Higher temperature and higher amounts of oxalic acid in the system accelerated the dissolution kinetics but did not result in higher solubility levels. Oxalic acid had also drawbacks in the process since higher amounts in the system promoted formation of a solid product, humboldtine (Fe(II)C2O4∙2H2O), which, in turn, inhibited the dissolution. This problem may be overcome by adding even a small amount of nitric acid to the system. Kinetic analysis showed, in the variable-rate-controlling step, that two linear fits of the Kabai model described the dissolution better in an oxalic acid and acid mixture of 70/30. Thermodynamic data and special cubic models showed that the nitric acid concentration had a significant role in the solubility, whereas the concentration of oxalic acid had only minor effects on solubility. The results also showed that measuring the oxalate and nitrate concentrations did not provide additional information about the dissolution mechanism itself. The pH, however, might be a tool for following the extent of dissolution, even though it is not a direct indicator of the dissolution mechanism.

Effect of incorporating hematite on the properties of ultra-high performance concrete including nuclear radiation resistance

Radiation is one of the most important problems for nuclear power plants. To fulfill the urgent need for building materials with high radiation resistance and improved mechanical and durability properties, a novel antiradiation ultra-high-performance concrete (UHPC) was designed. This was accomplished by using hematite powder to partially replace natural river sand at different replacement ratios. A series of tests were conducted, addressing fresh concrete’s fluidity, hardened concrete’s compressive strengths at room and elevated temperatures, impact strength, chloride resistance, radiation resistance, micropore structure, and hydration products. Experimental results show that the addition of hematite slightly decreased the work performance and compressive strength of UHPC, but substantially increased its flexural and impact strength and showed satisfactory high-temperature performance. The gamma-ray shielding performance of hematite UHPC was substantially enhanced by increasing the hematite replacement ratio. Compared with ordinary concrete, the linear attenuation coefficient of the UHPC with a 40% hematite replacement ratio increased by 43%, and the half-value layer thickness was reduced by 30%. The addition of hematite powder did not change the types of cement hydration products, but did improve the internal micropore structure, and cause the UHPC to exhibit excellent chloride ion penetration resistance.

Properties of High-Density Ultrahigh-Performance Concrete Containing Hematite Powder as a Partial Replacement of Sand

Properties of High-Density Ultrahigh-Performance Concrete Containing Hematite Powder as a Partial Replacement of Sand