Green steel at its crossroads: Hybrid hydrogen-based reduction of iron ores

Iron- and steelmaking cause ?7% of the global CO2 emissions, due to use carbon for reduction iron ores. Replacing by hydrogen as reductant offers a pathway massively reduce these emissions. However, production using renewable energy will remain one bottlenecks at least during next two decades, because making gigantic annual crude steel 1.8 billion tons sustainable requires minimum stoichiometric amount ?97 million green per year. Another fundamental aspect render ironmaking sector more lies in an optimal utilization energy, thus reducing efforts costly in-process recycling. We therefore demonstrate here how efficiency consumption ore can be dramatically improved knowledge-based combination technologies: partially low temperature via solid-state direct (DR) kinetically defined degree, subsequently melting completely transforming it under plasma (i.e. reduction, HPR). Results suggest that transition point between technologies occurs where their is equal. found hematite through magnetite into wüstite DR clean efficient, but gets sluggish inefficient when forms outermost layers pellets. Conversely, HPR starts violent unstable with arc delocalization, proceeds smoothly efficiently processing semi-reduced oxides, effect which might related material's high electrical conductivity. performed hybrid experiments pellets 700 °C 38% (using standard thermogravimetry system) transferring them HPR, conducted lean gas mixture Ar-10%H2 arc-melting furnace, achieve full conversion liquid iron. This approach allows exploit specific characteristics favourable regimes both technologies, while simultaneously showing potential keep improve both, process stability furnace longevity limiting its overexposure radiation.