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Jonathan Weiss | Dreamstime
Aleksandr Matveev | Dreamstime
The GreenIron process delivers sponge iron: a non-pyrophoric and “CO2-free,” high-grade metal that can be used as a steelmaking raw material in electric arc furnaces, smelting plants, foundries, as well as cooling material in basic oxygen steelmaking.

Pursuing Carbon-Neutral Iron for Steelmaking

Dec. 1, 2023
A reduction process that uses hydrogen fuel to recycle waste metal or treat ore will result in high-grade iron units, and a “completely CO2-free value chain,” according to the developers.

The regulatory pressure to decarbonize their processes is severe for manufacturing businesses but there is also pressure from capital lenders, and increasingly there is pressure from downstream buyers who want to certify that their suppliers uphold their commitment to carbon-neutrality. There is much discussion remaining to be had about the authenticity of carbon-neutrality claims and feasibility of net-zero goals, but the need to address those objectives is real. It is particularly intense for businesses that manufacture ferrous metal products. And to that end, there are multiple concepts in the offing and several projects in development are gaining serious consideration.

One project moving toward industrialization comes from a Swedish company called GreenIron H2 AB, a developer touting a hydrogen-based technology for recycling oxidized metals, as well as reducing virgin raw materials, namely iron ore. “We want to contribute to creating a completely CO2-free value chain, from the extraction of ore to the production of steel and various metals,” according to a recent statement. “Our greatest focus is on paving the way for a circular paradigm by producing valuable commodities from residues and waste.”

What GreenIron promises to deliver is a “CO2-free” high-grade metal – sponge iron, or direct reduced iron (DRI) – that can be used as a raw material by electric steelmakers, smelters, and foundries, to diminish the carbon footprints of their operations. Each of these operations are mainly scrap-based, but GreenIron’s pellets are also proposed as inputs for basic oxygen furnaces, as a cooling charge during steelmaking.

The GreenIron process begins with preparing the raw materials – ore (e.g., magnetite, hematite, wustite), slag, mill scale, filter dust, roasted pyrite, grinding swarf, various tailings, or other oxidized metals. This material is agglomerated using lignin, molasses, bentonite clay, or similar binder, and then pelletized or briquetted in a cold-forming step. The shape of these pellets will ensure proper hydrogen gas flow through the material once they reach the heating and reduction sequence.

After the pellets have been preheated to around 550 °C the batch is placed in a bell furnace, and flushed with an atmosphere of nitrogen gas (N2) that is then evacuated, to draw out any oxygen in the furnace chamber. Hot hydrogen gas (H2) is introduced, and the reduction process begins.

According to the developers, the reduction process works as a result of changes in gravity, temperature, and pressure, and its only by-product is water. The final material is sponge iron/DRI, a high-grade metal typically defined as 91-93% iron that can be stored and shipped safely.

GreenIron plans to start construction this winter of a full-scale production facility at an industrial park about 100 miles north of Stockholm, to start operation in 2024. It estimates that the annual production of a GreenIron furnace will be approximately 28,000 metric tons of DRI, which would mean that one furnace can reduce CO2 emissions by at least 56,000 mt per year versus a comparable iron source, mainly due to the use of hydrogen gas as the reduction agent. The process is also scalable, according to GreenIron.

The company has prepared for its commercialization stage by striking an agreement with Seco/Warwick Group to manufacture the atmosphere furnaces in which reduction will take place. “The long-term agreement provides for the delivery of a series of equipment. Cooperation in this technology area will provide us with development and cooperation in the area of pro-ecological solutions, which is in line with the company’s mission,” stated Seco CEO Sławomir Woźniak.