Electrorefining and Electrochemistry of Molten Iron and Iron-Carbon Electrodes in Slag

Despite a perpetual societal need for steel, the industry is facing critical challenges as more steel must be continually recycled to improve sustainability and close material loops in circular economies. A major issue here is producing high-value products and controlling elements like carbon in the face of stringent consumer requirements, volatile markets, low profit margins, and scrap irregularity. In this dissertation, a new electrorefining process was developed where molten iron is decarburized by imposing an electromotive force between it and a slag electrolyte at 1600–1700 °C. Upon anodic polarization, oxygen-containing anions react with carbon dissolved in molten iron, evolving gaseous carbon monoxide. As carbon is oxidized from the iron anode, valuable metallurgical-grade silicon is recovered as a by-product on counter electrodes. Electrorefining trials were conducted over the entire compositional range from 4.5 to 0.005 wt% C and shown capable of producing high-value ultra-low carbon steel containingPh.D