Kinetic model for reduction of iron oxide in molten slags by iron‐carbon melt

Abstract

Rate of reduction of iron oxide in iron and steelmaking slags by mass contents of dissolved carbon (>3%) in molten iron depends upon activity of FeO, temperature, mixing of bulk slag and other experimental conditions. A general kinetic model is developed by considering mass transfer of FeO in slag, chemical reaction at gas-metal interface and chemical reaction at gas-slag interface, respectively, as the three rate controlling steps. A critical analysis ot the experimental data reported in literature has been done. It is shown that in the case of slags containing mass contents of less than 5% FeO, the reduction of FeO is controlled by mass transfer of FeO in slag plus chemical reaction at gas-metal interface; when slags contain more than 40% FeO, the reduction of FeO is controlled by chemical reaction at gas-metal interface plus chemical reaction at gas-slag interface; at intermediate FeO mass contents (between ~ 5 and 40% FeO), the reduction of FeO is controlled by all three steps, namely, mass transfer of FeO in slag, chemical reaction at gas-metal interface and chemical reaction at gas-slag interface. The temperature dependence of rate constant for the gas-slag reaction is obtained as:where k 2 is expressed in mol m-2 s-1 bar-1 . The mass transfer coefficient of iron oxide in bulk slag is found to vary in the range 1.5x 1 o-5 to 5.0 x 1 o-5 mis, depending upon the slag composition as well as experimental conditions. Kinetisches Modell zur Reduktion der Eisenoxide in fliissigen Schlacken mitEisen-Kohlenstoff-Schmelzen. Die Geschwindigkeit der Reduktion von Eisenoxid in Eisen-und Stahlwerksschlacken mit in der Schmelze gelostem Kohlenstoff (>3%) hangt von der FeO-Aktivitat, Temperatur, Schlacke und anderen Versuchsbedingungen ab. Ein allgemeines kinetisches Modell wird entwickelt, daB den Stofftransport von FeO in die Schlacke, die chemische Reaktion an der GaslMetall-Grenzflache bzw. der GaslSchlacke-Grenzflache als die drei geschwindigkeitsbestimmenden Schritte berucksichtigt. Die in der Literatur angegebenen Versuchdaten werden kritisch analysiert. Es zeigt sich, daB bei Schlacken rnit FeO < 5% der Stofftransport von FeO in die Schlacke und die chemische Reaktion an der GaslMetall-Grenzflache die FeO-Reduktion bestimmen. Bei Schlacken mil FeO > 40% sind die chemischen Reaktionen an den Grenzflachen GaslMetall und GaslSchlacke geschwindigkeitsbestimmend. Fur mittlere FeO-Massengehalte (5-40%) wird die Reduktionsgeschwindigkeit von alien drei Mechanismen gemeinsam bestimmt. Die Temperaturabhangigkeit der Geschwindigkeitskonstante fur die GaslSchlacken-Reaktion erhalt man aus:In k2 = -32345, 4(±6128)/ T + 19, 0(±3, 42); 0'1nk2,1!T = ±0, 3. wobei k 2 in mol m-2 s-1 bar-1 angegeben wird. Der Stoffubergangskoeffizient von Eisenoxid in der Schlacke liegt im Bereich 1.5 x 1 o-5 bis 5.0 x 1 o-5 mis, je nach Schlackenzusammensetzung und Versuchsbedingungen. steel research 65 (1994) No. 10

Gas Slag Reaction Kinetics in Slag Cleaning of Copper Slags

“…The rate constant is expressed by (9) At T = 1723 K, the rate constant increased by a factor of 2.3 after also adding 10% Cu 2 O ( Figure 5). The rate constant was expressed by (10) The dependence of rate constant on temperature after …”

“…Step 1 becomes the rate determining step when the slag contains less than 5 wt% FeO [10]. So, in most cases, the two interfacial chemical reactions, step 2 gas slag reaction and step 4 gas carbon reaction, play important roles.…”

“…Some researchers found that the reduction of iron oxide proceeds via reducing gases which are produced after the injection of coal into the furnace. There are four possible rate determining steps during the reduction [7][8][9][10][11][12][13][14]. 1.…”

Rate of slag reduction in a laboratory electric furnace—alternating vs direct current

“…Boudouard reaction, CO absorption and reaction with the Galimov et al, [10] who reduced iron oxides in FeO-Fe 2 O 3 -slag, and nucleation of gaseous and metal products have all CaO-SiO 2 slags, also found that the rate of reduction been suggested as possible rate-controlling steps. [6][7][8][9][10][11][12][13][14][15][16][17][18] In increased significantly with increasing amount of trivalent general, the reduction process proceeds as follows:…”

Reduction kinetics of liquid iron oxide-containing slags by carbon monoxide

“…[16][17][18][19][20][21][22] Paul et al [17] concluded that for slags with less than 5 mass pct FeO, the rate of reduction by Fe-C droplets is controlled by mass transfer of FeO in the slag plus a chemical reaction at the gas-metal interface. For slags with more than 40 mass pct FeO, the reduction rate is controlled by a chemical reaction either at the gas/metal interface or at the gas/slag interface.…”