The Rate of Dissolution of Zircon in Molten Iron-Oxide

Abstract

The rate of dissolution of polycrystalline zircon in molten iron-oxide at 1500°C was studied under conditions of free and forced convection by rotating cylindrical zircon specimens in a stationary crucible containing the melt.Zircon specimen was about 20mm in diameter and 30mm long of about 25 percent apparent porosity. The specimens were rotated for 5 to 90 seconds at speeds of 0 to 800rpm in the melt. Then, the dissolution rate in molten iron-oxide at 1400°C to 1600°C was studied at 100rpm. The dissolution rate was calculated from the change in radius of the specimen.The dissolution rate in molten iron-oxide was extremely higher than both that of refractories in slag for manufacture of pig iron and that of alumina in molten iron-oxide. It was proportional to the square root of the speed of rotation, and it was dependent on temperature of the melt. There fore, we obtaind the view that the process of dissolution of zircon in molten iron-oxide under the conditions of this investigation is controlled by diffusion in the liquid boundary layer. Activation energy for the dissolution was about 80 kcal per mol. The interdiffusion coefficient was estimated to be about 1.7-8.5×10-3 sq. cm per sec at 1400°C to 1500°C.