Sustainable and highly efficient production of high-purity iron from oxide ores by acidic electrowinning in anion-rich electrolytes

Iron (Fe) and steel-making industries are major contributors to global CO2 emissions, accounting for 7% of total industry emissions. Electrolytic ironmaking processes emerge as one promising route for sustainable ironmaking, because of their potential to decarbonize process heat and eliminate carbon-based reductants, the two major carbon emission sources in ironmaking. Among various electrolytic ironmaking routes, molten oxide electrolysis and alkaline electrolysis have attracted the most attention in the past decade. Acidic electrolysis, despite its unique advantages, remains less studied due to the severe hydrogen evolution side reaction and the resulting low faradaic efficiency. In this work, we report a novel ironmaking process in acidic electrolytes, Acidic electro-Winning in Anion-Rich Electrolytes (AWARE), which successfully addresses the low-efficiency problem of acidic electrolysis by leveraging novel anion-rich electrolytes that were invented based on recent breakthroughs in aqueous electrolyte science. Both batch- and continuous-mode ironmaking were demonstrated using oxide Fe ores in various current densities. High-efficiency production (up to 99.8%) of high-purity Fe (>99%) from two oxide Fe ores (impurity up to 10.2 wt%) with high current densities (up to 1000 mA/cm2) at low temperatures (25-80°C) were demonstrated. The roles of process parameters (current, flow rate, type of feedstock, temperature) and electrolyzer design (electrolyte, electrode, and membrane) were systematically studied. A comprehensive analysis of the technological and economic potential of emerging electrolytic ironmaking processes was conducted. Based on the results and analysis, it is concluded that the proposed AWARE represents a new generation of sustainable ironmaking technology that has the potential to transform ironmaking due to its low operation temperatures (< 100 °C), high efficiency (>99%), high impurity tolerance, zero chemical usage, zero waste production, and zero carbon emissions.