Deoxidation of Molten Steel Using a Short‐Circuited Solid Oxide Electrochemical Cell

Abstract

Deoxidation of steel melts by short-circuiting an electrochemical cell has been demonstrated. A one-end closed yttria-stabilized zirconia (YSZ) tube, whose inner wall is coated with a porous molybdenum-YSZ cermet, is inserted into the steel melt. A reducing gas is passed through the tube, and a short circuit is established between the cermet and the melt. The deoxidation process has been analyzed and mathematically modeled by dividing the external short-circuit current into regions characterized by total resistance control and mass transport control. The kinetics are enhanced by increasing the oxygen mass-transfer coefficient in the melt (increasing melt stirring) and decreasing the total short-circuited cell resistance.

A Phenomenological Investigation on the Control of Oxides at the Interface Using an Electrochemical Cell

“…Previous researches on electrochemical cell reactions incorporated the methodologies of direct periodic melt samplings 3) or cell current measurements 4) to detect melt oxygen concentration in the bulk. Unlike the bulk periodic measurements, the cell potential (E cell ) of the present study is continuously measured for obtaining the oxygen concentration at the molten steel/MSZ interface (P O2 Inter ) calculated by using Eqs.…”

“…[1][2][3][4][5][6] In particular, stabilized zirconia has received much focus due to its selective permeability of oxygen ions and possible application to electrochemical deoxidation in high temperature extractive metallurgy. [2][3][4][5][6] Past work on electrochemical deoxidation was controlled on the bulk oxygen concentration change of the molten metal in the bulk and showed the deoxidation rate to be limited by the slow diffusion of oxygen.…”

Electrochemical Deoxidation of Molten Steel with Application of an Oxygen Permeable Membrane

“…The coating method employed in this study is similar to that in other studies. [6][7][8][9]20,21) For comparison, YSZ tube without coating is also used in deoxidation experiment. The YSZ tube is connected to an alumina tube with a ceramic adhesive.…”

“…Thus, electrochemical deoxidation has been proposed by several researchers in order to produce clean metals without inclusions. [1][2][3][4][5][6][7][8][9] Electrochemical deoxidation of liquid steel, which utilizes an oxygen-permeable membrane in the deoxidation process, eliminates the formation of solid inclusions from the beginning. It has started from the idea that oxygen can be removed from the steel melt to deoxidation agents without producing non-metallic solid inclusions under the oxygen chemical-potential gradient (Dm O 2 ) between two sides of the membrane.…”

“…The surface-exchange reactions occurring at the interfaces has been ignored by most investigators by assuming that the surface-exchange kinetics is rapid under the condition prevailing at the steel refining environment (high temperature). 4,7) In practice, however, interfacial process often makes a significant contribution to the overall permeating rate of the mixed ionic and electronic conducting membranes. An attempt to examine importance of the surface oxygen exchange reaction in determining the electrochemical deoxidation rate is made with the aim of developing a new refining technique to improve the aforementioned elec-…”