A New Concept for Refining Molten Metals and Recovering Metals from Slags

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The research involves a novel approach for refining metals. It will utilize the oxygen ion conducting properties of yttria stabilized zirconia (YSZ) solid electrolyte to rapidly remove oxygen from molten metals and slags. Typically, one side of the YSZ electrolyte will be in contact with the melt and the other side with a reducing gas without letting the gas and the melt come in direct contact with each other. This arrangement resembles an oxygen concentration cell, and therefore oxygen may be removed by passing an electric current through the electrolyte. This can be accomplished without the application of external potential by externally connecting (short circuiting) the electrodes on two sides of the electrolyte. The oxygen flux under this (short circuit) condition can be sufficiently high to rapidly deoxidize (refine) the melt. In order to efficiently remove oxygen by this technique, the YSZ electrolyte must be thin, and the electrodes must be porous and should cover the entire electrolyte surface for charge transfer. This novel refining device will be constructed and used as described above to study the kinetics of oxygen removal from copper, low carbon iron and lead oxide-silica melts. Based on the study the principal investigator will determine the rate- controlling step for oxygen removal in these systems and establish conditions for efficient refining. This new process for refining metals is environmentally sound, can use hydrogen and carbon containing reducing gases without running the risk of increasing hydrogen and carbon content of the melt, and is also rapid.