The Experts below are selected from a list of 4875 Experts worldwide ranked by ideXlab platform
H Y Sohn - One of the best experts on this subject based on the ideXlab platform.
-
interaction of magnesia carbon refractory with Ferrous Oxide under flash ironmaking conditions
Ceramics International, 2020Co-Authors: Rahul Sarkar, Barbara P Nash, H Y SohnAbstract:Abstract A novel flash ironmaking technology (FIT) that greatly reduces energy consumption and greenhouse gas emissions compared with blast furnace (BF) ironmaking has been developed at the University of Utah. In this technology, a falling stream of iron ore concentrate is directly converted to metallic iron by reducing gases such as hydrogen, natural gas or coal gas in a flash furnace. In this work, the interaction of magnesia-carbon (MgO–C) refractory with Ferrous Oxide (FeO) under the conditions of the novel FIT has been investigated. Oxidation of carbon from the MgO–C refractory occurred and magnesiowustite (MgxFe1-xO) solid solution was formed as a result of the interaction between magnesia (MgO) in the refractory and Ferrous Oxide (FeO). A solid-state diffusion based kinetics model was developed to describe the growth of the magnesiowustite (MgxFe1-xO) formed. Experiments were carried out with Ferrous Oxide (FeO) and MgO–C refractory in the temperature range 1200–1400 °C under flash ironmaking atmospheres. Reacted samples from FeO–MgO–C experiments were analyzed using Scanning Electron Microscopy-Energy Dispersive X-Ray spectroscopy (SEM-EDX) and Electron Probe Micro-Analyzer (EPMA) and the formation of the magnesiowustite solid solution under flash ironmaking conditions was confirmed. Using the kinetics model and the composition profiles determined with EPMA, the values of interdiffusion coefficient ( D F e − M g ) were determined as a function of the magnesiowustite composition. Also, an average value of the interdiffusion coefficient ( D ‾ F e − M g ) was calculated such that it reasonably reproduced the concentration profile of the cations over the entire composition range. The values of D ‾ F e − M g calculated in this work agreed closely with those obtained independently from experiments on the interaction between MgO–C and metallic Fe, thereby validating the interaction mechanism and the proposed kinetics model. The solid-state diffusion was a thermally activated process and the activation energy ( E a ) for D ‾ F e − M g was calculated as 398 kJ/mol.
-
interaction of Ferrous Oxide with alumina refractory under flash ironmaking conditions
Ceramics International, 2019Co-Authors: Rahul Sarkar, H Y SohnAbstract:Abstract A novel flash ironmaking technology (FIT) has been developed at the University of Utah based on the direct reduction of iron ore concentrate by a reducing gas such as hydrogen, natural gas, coal gas or a mixture thereof. In this work, the interaction of Ferrous Oxide (FeO) with alumina (Al2O3) refractory under flash ironmaking conditions has been studied. A thermodynamic basis for the interaction process has been developed by considering the Fe–Al–O system and a kinetic model based on solid-state diffusion is formulated to describe the growth of the hercynite (FeAl2O4) spinel formed as a result of the interaction between FeO and Al2O3. Experiments were conducted with FeO powders and pure Al2O3 refractory in the temperature range 1200–1400 °C under gas atmospheres relevant to FIT. The analyses of reacted samples using XRD, SEM-EDX and EPMA techniques confirmed the formation of the hercynite (FeAl2O4) spinel under FIT conditions and results showed that the proposed kinetic model appropriately describes the growth of the hercynite spinel layer, which obeyed the parabolic rate law at all the three temperatures. Furthermore, using the kinetic model, expressions for the parabolic rate-constants ( k 1 ) and the effective diffusivity ( D e f f ¯ ) were obtained and their respective values at the experimental temperatures were determined. The values of D e f f ¯ calculated in this study agreed closely with those obtained independently by the authors from experiments on Fe–Al2O3 interaction thereby corroborating the interaction mechanism and the associated reaction scheme. The solid-state diffusion was temperature-dependent, with an activation energy value of 268 kJ/mol.
Rahul Sarkar - One of the best experts on this subject based on the ideXlab platform.
-
interaction of magnesia carbon refractory with Ferrous Oxide under flash ironmaking conditions
Ceramics International, 2020Co-Authors: Rahul Sarkar, Barbara P Nash, H Y SohnAbstract:Abstract A novel flash ironmaking technology (FIT) that greatly reduces energy consumption and greenhouse gas emissions compared with blast furnace (BF) ironmaking has been developed at the University of Utah. In this technology, a falling stream of iron ore concentrate is directly converted to metallic iron by reducing gases such as hydrogen, natural gas or coal gas in a flash furnace. In this work, the interaction of magnesia-carbon (MgO–C) refractory with Ferrous Oxide (FeO) under the conditions of the novel FIT has been investigated. Oxidation of carbon from the MgO–C refractory occurred and magnesiowustite (MgxFe1-xO) solid solution was formed as a result of the interaction between magnesia (MgO) in the refractory and Ferrous Oxide (FeO). A solid-state diffusion based kinetics model was developed to describe the growth of the magnesiowustite (MgxFe1-xO) formed. Experiments were carried out with Ferrous Oxide (FeO) and MgO–C refractory in the temperature range 1200–1400 °C under flash ironmaking atmospheres. Reacted samples from FeO–MgO–C experiments were analyzed using Scanning Electron Microscopy-Energy Dispersive X-Ray spectroscopy (SEM-EDX) and Electron Probe Micro-Analyzer (EPMA) and the formation of the magnesiowustite solid solution under flash ironmaking conditions was confirmed. Using the kinetics model and the composition profiles determined with EPMA, the values of interdiffusion coefficient ( D F e − M g ) were determined as a function of the magnesiowustite composition. Also, an average value of the interdiffusion coefficient ( D ‾ F e − M g ) was calculated such that it reasonably reproduced the concentration profile of the cations over the entire composition range. The values of D ‾ F e − M g calculated in this work agreed closely with those obtained independently from experiments on the interaction between MgO–C and metallic Fe, thereby validating the interaction mechanism and the proposed kinetics model. The solid-state diffusion was a thermally activated process and the activation energy ( E a ) for D ‾ F e − M g was calculated as 398 kJ/mol.
-
interaction of Ferrous Oxide with alumina refractory under flash ironmaking conditions
Ceramics International, 2019Co-Authors: Rahul Sarkar, H Y SohnAbstract:Abstract A novel flash ironmaking technology (FIT) has been developed at the University of Utah based on the direct reduction of iron ore concentrate by a reducing gas such as hydrogen, natural gas, coal gas or a mixture thereof. In this work, the interaction of Ferrous Oxide (FeO) with alumina (Al2O3) refractory under flash ironmaking conditions has been studied. A thermodynamic basis for the interaction process has been developed by considering the Fe–Al–O system and a kinetic model based on solid-state diffusion is formulated to describe the growth of the hercynite (FeAl2O4) spinel formed as a result of the interaction between FeO and Al2O3. Experiments were conducted with FeO powders and pure Al2O3 refractory in the temperature range 1200–1400 °C under gas atmospheres relevant to FIT. The analyses of reacted samples using XRD, SEM-EDX and EPMA techniques confirmed the formation of the hercynite (FeAl2O4) spinel under FIT conditions and results showed that the proposed kinetic model appropriately describes the growth of the hercynite spinel layer, which obeyed the parabolic rate law at all the three temperatures. Furthermore, using the kinetic model, expressions for the parabolic rate-constants ( k 1 ) and the effective diffusivity ( D e f f ¯ ) were obtained and their respective values at the experimental temperatures were determined. The values of D e f f ¯ calculated in this study agreed closely with those obtained independently by the authors from experiments on Fe–Al2O3 interaction thereby corroborating the interaction mechanism and the associated reaction scheme. The solid-state diffusion was temperature-dependent, with an activation energy value of 268 kJ/mol.
Herman Terryn - One of the best experts on this subject based on the ideXlab platform.
-
a close up of the effect of iron Oxide type on the interfacial interaction between epoxy and carbon steel combined molecular dynamics simulations and quantum mechanics
Journal of Physical Chemistry C, 2016Co-Authors: Ghasem Bahlakeh, Mehdi Ghaffari, Frank De Proft, Mohammad Reza Saeb, Herman TerrynAbstract:In the present study, the effect of different types of iron Oxides, which naturally exist on steel substrate, on the interfacial interaction between an epoxy coating and a carbon steel substrate was studied at the molecular/atomic level by employing molecular dynamics (MD) simulations and quantum mechanics (QM) calculations. Three types of iron Oxide, that is, Ferrous Oxide (FeO), ferric Oxide (Fe2O3, hematite), and Ferrous ferric Oxide (Fe3O4, magnetite), were considered for modeling, and their binding energies were calculated and compared by altering the concentration of hydrOxide groups on the surface. To probe the effect of curing agent on interfacial interactions, computations were performed for either uncured or aminoamide-cured epoxy resins. The effect of the acid–base properties of the iron Oxide on the molecular bonding was theoretically investigated by imposing diverse iron hydrOxide/Oxide termination groups. Noticeably, MD and QM calculations confirmed rather well earlier experimental evaluatio...
Zhizhong Kang - One of the best experts on this subject based on the ideXlab platform.
-
distribution of clay minerals in light coal fractions and the thermal reaction products of these clay minerals during combustion in a drop tube furnace
Energies, 2016Co-Authors: Sida Tian, Yuqun Zhuo, Zhonghua Zhan, Xinqian Shu, Zhizhong KangAbstract:To estimate the contribution of clay minerals in light coal fractions to ash deposition in furnaces, we investigated their distribution and thermal reaction products. The light fractions of two Chinese coals were prepared using a 1.5 g·cm −3 ZnCl 2 solution as a density separation medium and were burned in a drop-tube furnace (DTF). The mineral matter in each of the light coal fractions was compared to that of the relevant raw coal. The DTF ash from light coal fractions was analysed using hydrochloric acid separation. The acid-soluble aluminium fractions of DTF ash samples were used to determine changes in the amorphous aluminosilicate products with increasing combustion temperature. The results show that the clay mineral contents in the mineral matter of both light coal fractions were higher than those in the respective raw coals. For the coal with a high ash melting point, clay minerals in the light coal fraction thermally transformed more dehydroxylation products compared with those in the raw coal, possibly contributing to solid-state reactions of ash particles. For the coal with a low ash melting point, clay minerals in the light coal fraction produced more easily-slagging material compared with those in the raw coal, playing an important role in the occurrence of slagging. Additionally, Ferrous Oxide often produces low-melting substances in coal ash. Due to the similarities of zinc Oxide and Ferrous Oxide in silicate reactions, we also investigated the interactions of clay minerals in light coal fractions with zinc Oxide introduced by a zinc chloride solution. The extraneous zinc Oxide could react, to a small extent, with clay minerals in the coal during DTF combustion.
Xiaodong Wen - One of the best experts on this subject based on the ideXlab platform.
-
Viscosity temperature properties from molecular dynamics simulation: The role of calcium Oxide, sodium Oxide and Ferrous Oxide
Fuel, 2019Co-Authors: Xin Dai, Jin Bai, Qing Huang, Zhen Liu, Xiaojing Bai, Ronggen Cao, Xiaodong WenAbstract:Abstract For the long-term stable operation of the entrained flow gasifier in the coal chemical industry, the flux agents are generally adopted to adjust the fusibility of coal ash. Therefore, it is necessary to understand the underlying mechanism for the impact of typical Oxide flux agents on viscosity temperature properties of coal ash from structures and thermodynamics. In this work, the role of calcium Oxide, sodium Oxide and Ferrous Oxide on viscosity temperature properties is investigated by a combination of molecular dynamics simulations and thermodynamic calculations. The variations of viscosity and temperature of critical viscosity are obtained for different ternary coal ash systems by thermodynamic calculation. Ternary phase diagrams are applied to evaluate the effect of different flux agents, which are also found to cause mineral transformation from high-temperature minerals to low-temperature minerals. Oxygen bond species are employed as the indicator of the structural evolution originating from addition of different flux agents. The sodium atoms may more readily weaken the tricluster oxygen bonds than calcium or Ferrous atoms according to the results. Higher content of bridging oxygen bonds in the sodium Oxide ternary coal ash system can enhance the stability of the structures and induce higher viscosity. Stability coefficients are defined here and a function to describe the relationship between the viscosity and flux agent content is established. The results from the current work are expected to provide new clues to find strategies controlling the fusion behaviour of coal ash systems.