The research work demonstrates the technical viability of employing
zirconia-based inert SOM anodes for environmentally sound and cost-effective
production of metals such as magnesium, tantalum, titanium, rare
earths, silicon, aluminum, etc., by directly reducing them from
their oxides. The inert anode consists of the oxygen-ion-conducting
stabilized zirconia membrane in intimate contact on one side with
a catalytically active electronic phase. The opposite (other) side
of the zirconia membrane is placed in contact with an ionically
conducting solvent phase containing the desired oxide for reduction.
A cathode is placed in the solvent and an appropriate electric potential
is applied between the electrodes to electrolyze the metals from
The full-benefit of the process can be realized if it is
conducted at temperatures between 1000-1400°C. At these temperatures
the ohmic resistance drop across the stabilized zirconia membrane
are low and therefore high current densities on the order of 1 A/cm2
or greater can be obtained. In addition, the process efficiency
can be further increased by directly reforming hydrocarbon fuel
over the anode.
Topics covered in this research include: stability of the
zirconia membrane in the selected molten solvent (flux), volatility
of the flux, transport processes, potentiodynamic sweeps, electrolysis
experiments, metal recovery and analysis and process scaleup.