Iron Electrowinning Lab

Low-temperature iron electrowinning (LT-EW, commercialized by pioneers like Electra and the European Siderwin consortium) is an electrochemical steelmaking process that operates between 60°C and 110°C in an aqueous alkaline electrolyte (concentrated sodium hydroxide solution). Instead of burning metallurgical coal or coke at 1,600°C in a blast furnace, electrical current directly reduces dissolved iron oxide into 99.99% pure elemental iron plates at the cathode, releasing only pure oxygen gas at the anode with zero direct CO2 emissions.

Green hydrogen direct reduction (H2-DRI) in shaft furnaces requires scarce, expensive direct-reduced (DR) grade iron ore pellets containing over 67% iron and minimal impurities, representing less than 4% of global iron reserves. In contrast, low-temperature electrowinning selectively leaches iron oxide into liquid solution while gangue minerals (such as silica, alumina, and phosphorus) remain insoluble solids. These impurities are filtered out mechanically at under 100°C, enabling the use of abundant commercial ores (35% to 55% Fe) and mine tailings without high-temperature smelting.

Green hydrogen DRI steelmaking requires roughly 3.5 to 4.5 MWh of electricity per tonne of iron, primarily because water electrolysis incurs significant round-trip thermodynamic conversion losses (roughly 50 kWh/kg H2) before hydrogen ever reaches the reduction furnace. In direct electrowinning, electrons transfer directly from the electrical circuit to iron ions in solution at 1.8 to 2.2 V, achieving specific electricity consumption of only 2.4 to 2.8 MWh per tonne of pure iron—a 30% to 40% reduction in total electric power requirements.

The anodic half-reaction (4 OH- -> O2 + 2 H2O + 4 e-) generates approximately 0.43 tonnes of high-purity oxygen gas per tonne of pure iron plate produced. In an integrated steel manufacturing complex, this clean oxygen stream can be directly piped to downstream electric arc furnaces (EAF) or chemical plants, completely eliminating the capital cost and electrical consumption of separate cryogenic air separation units (ASU) and generating an economic credit of $35 to $60 per tonne of oxygen.

Capital expenditures are dominated by modular electrowinning cell tanks, high-current DC power rectifiers, automated cathode plate harvesting cranes, and liquid-solid filtration circuits ($400 to $550 per annual tonne of capacity). Because the process utilizes inexpensive low-grade iron ore ($30 to $65/tonne) and benefits from low electricity intensity, net levelized cost of pure iron (LCOI) ranges between $280 and $380 per tonne of iron, making it directly cost-competitive with coal blast furnaces when carbon border adjustment tariffs (EU CBAM) or carbon prices are applied.