Hydrogen Dissolution in the TiO2–SiO2–FeO and TiO2–SiO2–MnO Based Welding-Type Fluxes

The hydrogen solubility in the CaF2-CaO-SiO2 slag system has been studied to identify and compare the hydrogen dissolution behavior according to basicity and CaF2 content at high temperature of 1 823 K. The hydrogen solubility typically increases with higher CaF2 content across the entire compositional range, but its effect is more pronounced at higher basicity. At low basicity, CaF2 seems to slightly polymerize the slag network increasing the available incorporation sites, where hydrogen can attach and increase hydrogen content in slag. At high basicity, the slag structure is already highly depolymerized and CaF2 addition does not affect the silicate structure, but likely affects the slag hydrogen solubility by lowering the hydroxyl activity. CaO additions lowered the hydrogen content in slag at low basicity and increased the hydrogen content in slag at high basicity. From the temperature dependence of the hydrogen solubility, the dissolution energy of hydrogen in slag was found to be 42.3 kcal/mol.

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“…Verification and reproducibility of the hydrogen analysis has been provided in a previously published paper. 20) …”

Section: Methodsmentioning

confidence: 99%

Hydrogen Dissolution in the CaF2–CaO–SiO2 System

2011

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“…(2) The Effect of the FeO t Content on the Slag Structure at Fixed CaO/SiO 2 Ratios Using FTIR Our previous work 55,56 showed that the dissolution of hydrogen in slag is affected by the degree of slag polymerization and the number of available reaction sites. This polymerization and slag networking effect was ascertained by FTIR and Raman spectroscopy, similarly to Mysen et al [47][48][49] and McMillan.…”

Section: Resultsmentioning

confidence: 99%

Effect of FeO_t Content and CaO/SiO₂ Ratio on Hydrogen Dissolution in CaF₂–CaO–SiO₂‐Based Welding Fluxes

Park

Park²,

Chang³

et al. 2012

J. Am. Ceram. Soc.

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The solubility of hydrogen in the CaF2–CaO–SiO2–FeOt slag system was studied to characterize the dependence of hydrogen dissolution behavior on the CaO/SiO2 ratio and the Fe3+/Fe2+ redox equilibrium at 1823 K. In an acidic slag composition, the dissolved hydrogen seems to exist as an incorporated hydroxyl, where the supplied water vapor reacts with the bridged oxygen (Oo) of the slag network. In a basic slag composition, hydrogen dissolves as a free hydroxyl in the molten slag by reacting with the free oxygen (O2−). Using FTIR (Fourier transform infrared) and Raman spectroscopy, the addition of FeOt depolymerized the slag structure in an acidic slag system, but polymerized the slag structure in a basic slag system as the FeOt content increased. Furthermore, the formation of γ‐ and δ‐FeO(OH) was controlled by the amount of Fe2O3 present in the flux and increased at higher concentrations of Fe2O3. At a fixed Fe2O3 content and with CaO/SiO2 ratios varying from 0.7 to 1.3, the hydrogen solubility curve was parabolic as a function of CaO/SiO2, with a minimum near the CaO/SiO2 ratio of 1.0 and rapidly increasing at CaO/SiO2 ratios above 1.0.

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“…Therefore, the slag can pick up hydrogen and water vapor, then transfer it to the liquid metal. Many studies [47][48][49][50] have been done to investigate the solubility of hydrogen in slags. Walsh et al [43] studied the solubility of hydrogen in steelmaking slags.…”

Section: Solubility Of Hydrogenmentioning

confidence: 99%

Thermodynamic of Liquid Iron Ore Reduction by Hydrogen Thermal Plasma

Seftejani

Schenk

2018

Metals

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The production of iron using hydrogen as a reducing agent is an alternative to conventional iron- and steel-making processes, with an associated decrease in CO2 emissions. Hydrogen plasma smelting reduction (HPSR) of iron ore is the process of using hydrogen in a plasma state to reduce iron oxides. A hydrogen plasma arc is generated between a hollow graphite electrode and liquid iron oxide. In the present study, the thermodynamics of hydrogen thermal plasma and the reduction of iron oxide using hydrogen at plasma temperatures were studied. Thermodynamics calculations show that hydrogen at high temperatures is atomized, ionized, or excited. The Gibbs free energy changes of iron oxide reductions indicate that activated hydrogen particles are stronger reducing agents than molecular hydrogen. Temperature is the main influencing parameter on the atomization and ionization degree of hydrogen particles. Therefore, to increase the hydrogen ionization degree and, consequently, increase of the reduction rate of iron ore particles, the reduction reactions should take place in the plasma arc zone due to the high temperature of the plasma arc in HPSR. Moreover, the solubility of hydrogen in slag and molten metal are studied and the sequence of hematite reduction reactions is presented.

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Hydrogen Dissolution in the TiO2–SiO2–FeO and TiO2–SiO2–MnO Based Welding-Type Fluxes

Cited by 13 publications

References 9 publications

Hydrogen Dissolution in the CaF2–CaO–SiO2 System

Hydrogen Dissolution in the CaF2–CaO–SiO2 System

Effect of FeO_t Content and CaO/SiO₂ Ratio on Hydrogen Dissolution in CaF₂–CaO–SiO₂‐Based Welding Fluxes

Thermodynamic of Liquid Iron Ore Reduction by Hydrogen Thermal Plasma

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Hydrogen Dissolution in the TiO2–SiO2–FeO and TiO2–SiO2–MnO Based Welding-Type Fluxes

Cited by 13 publications

References 9 publications

Hydrogen Dissolution in the CaF2–CaO–SiO2 System

Hydrogen Dissolution in the CaF2–CaO–SiO2 System

Effect of FeOt Content and CaO/SiO2 Ratio on Hydrogen Dissolution in CaF2–CaO–SiO2‐Based Welding Fluxes

Thermodynamic of Liquid Iron Ore Reduction by Hydrogen Thermal Plasma

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Effect of FeO_t Content and CaO/SiO₂ Ratio on Hydrogen Dissolution in CaF₂–CaO–SiO₂‐Based Welding Fluxes