Interfacial kinetics of hydrogen with liquid slag containing iron oxide

Abstract

Interfacial kinetics on the hydrogen reduction of liquid Fe t O in Fe t O-M x O y slag (M x O y ϭ CaO, SiO 2 , Al 2 O 3 , and TiO 2 ) has been studied at 1673 K. Because the rate of hydrogen reduction was very fast, the rate was controlled by gas-phase mass transfer under most of the experimental conditions. The effect of CaO or SiO 2 addition on the interfacial chemical reaction rate of hydrogen reduction was empirically evaluated as a function of the ferrous-ferric ratio in the slag. The observed interfacial chemical reaction rates in Fe t O-CaO and Fe t O-SiO 2 slags showed reasonable agreement with the estimated values. Most of the available literature data on the reduction rate of liquid iron oxide by solid carbon, hot metal, and reducing gases were also reviewed and compared with the results of the present work. It was found that the rate of hydrogen reduction of liquid iron oxide slag is much faster than that with other reducing agents such as solid carbon, carbon dissolved in the liquid iron, and CO gas.

A comprehensive kinetic model for the CO-CO2 reaction with iron oxide-containing slags

“…[1][2][3][4][5] Our knowledge of the kinetics and mechanism of such reactions has grown significantly since then. In particular, the reaction between CO-CO 2 [2,[6][7][8][9][10][11][12][13][14][15][16][17][18] and H 2 -H 2 O [19,20] with iron oxide in the slag have attracted considerable attention, owing to the significance of the reactions in a number of metallurgical processes including direct smelting of iron, electric steelmaking, and nonferrous metals refining. The reaction between the slag and CO-CO 2 atmospheres in its simplest form can be written as [1] with a general agreement between different studies that the rate of oxygen transfer with melts follows the form [2] In this equation, a o is defined as the CO 2 /CO ratio of the gas in the local equilibrium with the slag (with the unit CO 2 /CO as the standard state), and the apparent rate constant (k a ) has found to be a complex function of the bulk slag composition, a o , and temperature, rather than a simple temperature-dependent rate constant.…”

“…[18], is the Boltzman constant and ⌽ represent the energy required to move one electron from the Fermi level to the conduction band at the surface. Regardless of the extent and direction of conduction-band bending, ⌽ is given by [19] where the surface potential (⌽ S ) acquires positive values for the case of positive-charge accumulation at the surface.…”

Kinetics of CO-CO2 reaction with CaO-SiO2-FeOx melts

“…Several profound reviews have been given by Nagasaka et al, [33] Jahanshahi and Sun, [34] and Belton [35] on the topic of gas-liquid slag reaction kinetics. Many aspects of the reaction have been studied and empirical relationships have been reported about the dependence of the rate constant on the slag chemistry.…”

Influence of TiO2 on the Viscous Behavior of Calcium Silicate Melts Containing 17 mass% Al2O3 and 10 mass% MgO

“…Iron ores consisting of significant TiO2 such as ilmenite are low cost ores, but due to the high TiO2 content its use may result in significant issues within the blast furnaces such as lower reduction degree, [1][2][3][4] changes in the liquidus temperature in slag, [5][6][7] lower residual removal by the slag, [8][9][10] and viscosity changes within the bosch and hearth. [11][12][13][14][15] However, potential benefits of TiO2 in the blast furnace slags have also been known by forming a protective layer of titanium carbo-nitride on the refractory brick and inhibiting the premature failure and erosion of the hearth.…”