New process for continuous melting and pouring of oxides with skull melting crucible

Abstract

A distinctive feature of induction furnaces with cold crucible is the skull melting without introducing any impurities in the melt and overheating of the melt over 3000°C at air. Therefore the technology of induction melting in cold crucible is suitable for high temperature synthesis of oxide materials. This paper describes a new technology for continuous melting and pouring of oxide melts. A new type of cold crucible with two chambers is used for this application. In the first chamber the charged oxide is melted and transferred via a barrier to the second chamber where the oxide is superheated before pouring over a discharging hole. During the transfer of the melted oxide from the melting zone into the superheating zone the transport of non-melted oxide particles has to be avoided. This transport is mainly influenced by the hydrodynamics of the melt flow and the temperature field during melting and pouring. Numerical simulation is used to investigate the heat and mass transfer during the melting and pouring processes in the cold crucible furnace. Both forced and free convections are taken into account in the simulation. Apart from the melt flow inside the cold crucible special attention is also paid to the behavior of the pouring stream. The numerical results are compared with experimental data of melting and pouring experiments in the skull melting installation at the Institute of Electrotechnology. The paper presents a description of the cold crucible setup, the results of the numerical simulation and comparison of them with experimental data.