Determination of the Rate of CO2 Dissociation on the Surface of CaO-SiO2, CaO-Al2O3, CaO-SiO2-CaF2 and CaO-SiO2-FexO Melts.

Abstract

The rate constant of C02 dissociation on the surfaces of CaO-Si02' CaO-Al203' CaO-Si02-CaF2and CaO-Si02-Fe.Oslags was measuredby means of a 13C02-CO isotope exchangetechnique as functions of slag basicity, iron content, temperature and imposed equilibrium C02/CO ratio, It was shown that CaOSi02-Fe*O slags with low iron content and those with high iron content had different rate determining steps, According to those rate determining steps, the apparent rate constant, k., was ca]culated for each slag. Consequently, we obtained the equations: k. =k(1 -~iei) and k.=k(1 -~iei) ( If weassume that the dissociation of adsorbed C02 on the surface of slag controls an overall reaction, with the adsorption equilibrium for C02and CO, reactions (4) and (6) that the reverse rate of reaction (7) may be negligible.Therefore, the measurement of the forward rate of reaction (7) mol~1)) is the gas constant. AP*3c0= and (P*3co)*q are the partial pressure decrease of P*=c02 by reaction (7) and the partial pressure of P*3co when the complete isotope exchangeequilibrium was achieved, respectively. Hereafter, the left hand side of Eq. (9) will be represented by k* as the apparent forward rate constant.2.2. Experimental ArrangementThe experimentai arrangement is shown in Fig. l Fig. 8.

Interfacial Rate of CO2^|^ndash;CO Reaction with the Solid Iron and Iron Oxide by Isotope Exchange Technique at 1273 K

“…The relationship of can be simply given and has been confirmed in some slag systems. 5,7,11) For the solid iron oxide system, the whole experimental system is in a chemical equilibrium, therefore it can be considered as a homogeneous phase. Especially in wüstite phase (Fe1-yO) region, the values of y change in the range of 0.05-0.12 at 1 273 K, 22) and it is acceptable that the effect of CO2/CO ratio on is so small that can be ignored.…”

“…From the 1960s, the isotope exchange technique, as an effective experimental method to study the interfacial kinetics between gas and iron oxide, has been extensively used by many researchers in metallurgical field. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Recently, in order to meet the strong demand on the utilization of low grade iron ores and reduction of CO2 emission, the direct reduction of fine iron ore, as an innovative ironmaking process, has been given more attention. Therefore, the kinetics of CO2-CO reaction with the solid iron oxide became more important.…”

Surface Active Effect of Na2O on the Rate of CO2 Dissociation on the Surface of Molten FeOx-Na2O and FeOx-SiO2-Na2O Systems

“…Therefore, oxidation or reduction rates for FeO x -contained molten oxides have been widely investigated. [1][2][3][4][5][6][7][8][9][10][11][12][13] Researches about the reduction rate of FeO x and FeO x -based molten oxides with CO-CO 2 gas have been conducted by many researchers. Tsukihashi et al 2) measured the reduction rate of molten iron oxide in CO gas conveyed system at 1 723 and 1 873 K. Fine powders of iron oxide were utilized to eliminate the effect of gas phase mass transfer rate on the overall reaction rate of reduction.…”

Effect of P2O5 Addition on the Rate of CO2 Dissociation on the Surface of FetO-base Molten Oxides

“…Therefore, the kinetic data of CO-CO 2 reaction are important for the analysis, simulation and the development of refining processes. Especially in the ironmaking and steelmaking processes, for development of the bath smelting process as an innovative process, this reaction rate has been widely investigated by many researchers [1][2][3][4][5][6][7][8][9][10][11][12][13] and the reduction rate of molten oxides containing iron oxide is expressed as the function of temperature and the Fe 3ϩ /Fe 2ϩ ratio of the molten oxides. However, this relationship cannot be applied when the strong surface active elements such as P 2 O 5 or Na 2 O are contained in molten oxides.…”