A closed-loop hydrometallurgical process for low-carbon iron processing

Electrification will be a key factor in decarbonizing hard-to-abate sectors, but challenges arise in applications that require very high temperatures, such as steel production. The intense heat requirements for converting iron ore into metal contribute significantly to the CO₂ emissions of the steel sector. A new hydrometallurgical process that promises to remove CO₂ from this process is being scaled up in a new pilot plant operated by Electra (Boulder, Colo.; www.electra.earth). “Unlike traditional methods that rely on high temperatures near 3,000°F to melt and chemically transform ores, which emits significant amounts of CO₂, Electra’s technology operates at 140°F, enabling seamless integration of intermittent renewable energy resources and making emissions-free iron possible,” says Trevor Braun, Electra’s senior manager of electrochemical development & testing.

Besides lower operating temperatures, one of the reasons that Electra’s process is so suitable for electrification is its ability to start and stop production quickly, which promotes the use of intermittent renewable electricity when it is available.

“Electra’s process can utilize a wide variety of iron ores, even already-mined feedstock, dissolving them in an acidic solution using a proprietary process. Then, we use a hydrometallurgy technique to purify the solution, where all the impurities are removed and refined into separate co-products, such as alumina and silica. After purifying the iron solution, we use electricity to deposit the iron from the solution onto reusable metal plates. The iron metal is then harvested from the steel plates and sent to the steelmaker,” explains Braun. This closed-loop process regenerates consumables, such as water and acid, enabling circular clean-iron production.

Since 2020, the process has scaled up from producing 50-cm ² iron plates in a bench-scale system to commercially relevant 1-m ² plates. “The pilot plant will continue to evaluate iron ores from all over the world, focusing on impurity removal to produce 99% pure iron. We’re currently evaluating sites throughout the U.S. for the first phase of our commercial deployment,” adds Braun.