EFFECT OF THE BUBBLE-SIZE AND CHEMICAL-REACTIONS ON SLAG FOAMING

Slag foams have been investigated with smaller bubbles than those used in the previous studies.[(5),(6),(7)] The bubbles were generated by a rgon gas injection with the nozzle of multiple small orifices and by t he slag/metal interfacial reaction of FeO in the slag with carbon in t he liquid iron. The foam stability in terms of the foam index for a ba th-smelting type of slag (CaO-SiO2-Al2O3-FeO) was determined for diffe rent bubble sizes. The average diameter of bubbles in the foam was mea sured by an X-ray video technique. When the foam was generated by the slag/metal interfacial reaction at 1450 degrees C, it was found that t he average bubble diameter varied from less than 1 to more than 5 mm a s a function of the sulfur activity in the carbon-saturated liquid iro n. The foam index was found to be inversely proportional to the averag e bubble diameter. A general correlation is obtained by dimensional an alysis in order to predict the foam index from the physical properties of the liquid slag and the average size of the gas bubbles in the foa m.