A Review on the Kinetics of Iron Ore Reduction by Hydrogen

A clean energy revolution is occurring across the world. As iron and steelmaking have a tremendous impact on the amount of CO2 emissions, there is an increasing attraction towards improving the green footprint of iron and steel production. Among reducing agents, hydrogen has shown a great potential to be replaced with fossil fuels and to decarbonize the steelmaking processes. Although hydrogen is in great supply on earth, extracting pure H2 from its compound is costly. Therefore, it is crucial to calculate the partial pressure of H2 with the aid of reduction reaction kinetics to limit the costs. This review summarizes the studies of critical parameters to determine the kinetics of reduction. The variables considered were temperature, iron ore type (magnetite, hematite, goethite), H2/CO ratio, porosity, flow rate, the concentration of diluent (He, Ar, N2), gas utility, annealing before reduction, and pressure. In fact, increasing temperature, H2/CO ratio, hydrogen flow rate and hematite percentage in feed leads to a higher reduction rate. In addition, the controlling kinetics models and the impact of the mentioned parameters on them investigated and compared, concluding chemical reaction at the interfaces and diffusion of hydrogen through the iron oxide particle are the most common kinetics controlling models.

A novel monitoring scheme to detect iron oxide particle deposits on the internal surface of PVC drinking water pipes

PVC pipe wall samples were acquired from a full-scale drinking water distribution laboratory using 3D printed coupons. Brightfield microscopy and imaging processing were used to investigate iron oxide particles deposited on samples surface.

Sources and Characteristics of Particulate Matter in Subway Tunnels in Seoul, Korea

Hazards related to particulate matter (PM) in subway systems necessitate improvement of the air quality. As a first step toward establishing a management strategy, we assessed the physicochemical characteristics of PM in a subway system in Seoul, South Korea. The mean mass of PM10 and PM2.5 concentrations (n = 13) were 213.7 ± 50.4 and 78.4 ± 8.8 µg/m3, with 86.0% and 85.9% of mass concentration. Chemical analysis using a thermal–optical elemental/organic carbon (EC–OC) analyzer, ion chromatography (IC), and inductively coupled plasma (ICP) spectroscopy indicated that the chemical components in the subway tunnel comprised 86.0% and 85.9% mass concentration of PM10 and PM2.5. Fe was the most abundant element in subway tunnels, accounting for higher proportions of PM, and was detected in PM with diameters >94 nm. Fe was present mostly as iron oxides, which were emitted from the wheel–rail–brake and pantograph–catenary wire interfaces. Copper particles were 96–150 nm in diameter and were likely emitted via catenary wire arc discharges. Furthermore, X-ray diffraction analysis (XRD) showed that the PM in subway tunnels was composed of calcium carbonate (CaCO3), quartz (SiO2), and iron oxides (hematite (α-Fe2O3) and maghemite-C (γ-Fe2O3)). Transmission electron microscopy images revealed that the PM in subway tunnels existed as agglomerates of iron oxide particle clusters a few nanometers in diameter, which were presumably generated at the aforementioned interfaces and subsequently attached onto other PM, enabling the growth of aggregates. Our results can help inform the management of PM sources from subway operation.

Comparative Efficacy of Autologous Stromal Vascular Fraction and Autologous Adipose-Derived Mesenchymal Stem Cells Combined With Hyaluronic Acid for the Treatment of Sheep Osteoarthritis

The current study explored whether intra-articular (IA) injection of autologous adipose mesenchymal stem cells (ASCs) combined with hyaluronic acid (HA) achieved better therapeutic efficacy than autologous stromal vascular fraction (SVF) combined with HA to prevent osteoarthritis (OA) progression and determined how long autologous ASCs combined with HA must remain in the joint to observe efficacy. OA models were established by performing anterior cruciate ligament transection (ACLT) and medial meniscectomy (MM). Autologous SVF (1×107 mononuclear cells), autologous low-dose ASCs (1×107), and autologous high-dose ASCs (5×107) combined with HA, and HA alone, or saline alone were injected into the OA model animals at 12 and 15 weeks after surgery, respectively. Compared with SVF+HA treatment, low-dose ASC+HA treatment yielded better magnetic resonance imaging (MRI) scores and macroscopic results, while the cartilage thickness of the tibial plateau did not differ between low, high ASC+HA and SVF+HA treatments detected by micro-computed tomography (µCT). Immunohistochemistry revealed that high-dose ASC+HA treatment rescued hypertrophic chondrocytes expressing collagen X in the deep area of articular cartilage. Western blotting analysis indicated the high- and low-dose ASC+HA groups expressed more collagen X than did the SVF+HA group. Enzyme-linked immunosorbent assay showed treatment with both ASC+HA and SVF+HA resulted in differing anti-inflammatory and trophic effects. Moreover, superparamagnetic iron oxide particle (SPIO)-labeled autologous ASC signals were detected by MRI at 2 and 18 weeks post-injection and were found in the lateral meniscus at 2 weeks and in the marrow cavity of the femoral condyle at 18 weeks post-injection. Thus, IA injection of autologous ASC+HA may demonstrate better efficacy than autologous SVF+HA in blocking OA progression and promoting cartilage regeneration, and autologous ASCs (5×107 cells) combined with HA potentially survive for at least 18 weeks after IA injection.

INVESTIGATION OF SURFACES OF NOVEL IRON OXIDES WITH GRAIN AND GRAIN BOUNDARY

Hierarchical nano/microscale α-Fe2O3 iron oxide particle system was prepared by an improved and modified polyol method with the use of NaBH4 agent with high heat treatment at 900 °C in air. Here, α-Fe2O3 iron oxide particles with different shapes were analyzed. The morphologies of the surfaces of α-Fe2O3 iron oxide particles show the oxide structures with the different nano/microscale ranges of grain sizes. In this research, we have found that grain and grain boundary growth limits can be determined in α-Fe2O3 iron oxide structure. This leads to the possibility of producing new iron oxide structures with distribution of desirable size grain and grain boundary. With α-Fe2O3 structure obtained, the magnetic properties of the α-Fe2O3 iron oxide system are different from those of previously reported studies. in national and international studies.Keywords: Iron iron oxides, α-Fe2O3, chemical polyol methods, heat treatment.

Effect of hydrogenation on the structure and magnetic properties of an iron oxide cluster

Hydrogenation of an iron oxide particle influences the geometrical topology and total magnetic moment and invokes different superexchange mechanisms.

CATALYTIC ACTIVITY OF ZSM-5 ZEOLITE LOADED WITH TRANSITION METALS FOR THE SELECTIVE CATALYTIC REDUCTION OF NOX

Catalytic activity measurement were carried out on catalysts formulated from ZSM-5 zeolite separately loaded with transition metals (Cu, Co, Ni, Fe) for the removal of NOx in simulated diesel exhaust conditions. Various factors were investigated to compare the performance of these catalysts including catalyst preparation method, Si/Al ratio of the parent zeolite support, and durability in the exhaust stream containing water vapor or SO2. In many experimental conditions except in the presence of water vapor or SO2, Cu-ZSM5 remained the most active catalyst with 100% NOX conversion at around 350°C. C0-ZSM5 and Ni-ZSM5 could also achieve complete NOx conversion but at a much higher temperature of around 450°C. Fe-ZSM5 catalyst was the least active catalyst probably due to the formation of iron oxide particle, which accelerated formation of carbon monoxide.