Permeability, diffusivity, and solubility of oxygen gas in liquid slag

Abstract

An experimental procedure for measurement of the permeability of dissolved oxygen gas in liquid slag has been developed using an oxygen concentration cell. The small amount of oxygen gas which penetrated through the liquid oxide from a pure oxygen compartment to a pure argon compartment was determined by the galvanic cell. The permeabilities of oxygen through liquid PbO-SiO2 and FeO-PbO-SiO2 were found to be in the range 3 x 10-8 to 3 x 1O-7 moles/cm s. The permeabilities were little influenced by temperature but more influenced by the composition. In separate experiments, the oxygen pressure change at the bottom of a column of slag was detected by another galvanic cell. By this method, it is not necessary to quench the specimen to determine the concentration profile of dissolved oxygen and to determine its diffusivity. Liquid oxides in the PbO-SiO2, CaO-SiO2-Al2O3and FeO-PbO-SiO2 systems were studied. The oxygen diffusion coefficients (5 x 10-5 to 3 x 10-3 cm2/s) were found to increase with temperature for a fixed composition of slag, and with an increase of network-modifier oxide content at constant temperature. The solubility of oxygen gas in PbO-SiO2 melts was estimated to be 2 x 10-4 to 2 x 10-5 moles/cm3 from the determined diffusivities and permeabilities. The solubilities decreased with increasing temperature in the composition range studied. Physical solubilities of gases and metals in slags determined by other investigators are compared with the present results.