Direct Reduction of Solid Fe2O3 in Molten CaCl2 by Potentially Green Process

Sintered (300 degrees C) porous pellets of Fe2O3 were electrolyzed to Fe in molten CaCl2 (800-900 degrees C) under argon at 1.8-3.2 V for 2-20 h. The laboratory scale experiments show that it was a potentially direct green method to produce Fe powder. At lower electrolysis voltage (<2.2 V), higher current efficiency (>90%) and smaller energy consumption (similar to 3.0 kWh/kg) can be obtained. When the electrolysis voltage was above 2.4 V, the deposition of metal Ca from the salt lowered the current efficiency and increased the energy consumption. The electrolysis voltage also had effects on the micrographs of the reduced powder. The cubic particles can be seen in the products at the voltage lower than 2.2 V; when the voltage was higher than 2.2 V, it was nodular. The reduction proceeds at the cathode in two steps, i.e., from Fe2O3 to FeO and then to Fe. The oxygen emits at the anode. The process is potentially free of carbon emission and produces two useful products at both cathode and anode, promising a zero-emission technology for the extractive metallurgical industry.