Our technology

Step 1. Input materials

The input – oxidised materials – arrive to the plant. These can have different shapes and metal content. The input materials can be metal ore, slag, mill scale, filter dust, roasted pyrite, grinding swarf, various tailings, or other oxidised materials.

Step 2. Material pre-processing

The input material needs to be agglomerated. To do so, there is a pelletising/briquetting machine in connection to our reduction furnace. Binders are used to agglomerate the material, these can for instance be lignin, molasse, bentonite, or other. The material is cold-formed without heating and therefore energy-saving. Their shape ensures gas flow through the material bed, which is required during the heating and reduction.

The material is loaded into a perforated metal barrel which will allows the process gases flow freely through the batch to the heat recovery system. The batch is pre-heated to minimise the processing time.

Step 3. Reduction of metal oxide to metal

The batch is placed in the bell furnace when it has reached the desired temperature: around 600 °C. The internal atmosphere is flushed with nitrogen gas (N₂) and thereafter evacuated. In this step, the main goal is to control the internal environment, where elimination of the oxygen gas (O₂) is of great importance. Hot hydrogen gas (H₂) is then introduced into the chamber and the reduction process starts.

Our only by-product, water, is formed during the reduction. The reduction process is designed to work with gravity and temperature as well as pressure changes. In addition, the process is internally circular: the incoming hydrogen is heated by the outgoing gas with minimal heat loss. Overall, it makes our process very energy efficient. Water continues to form in until all available oxygen in the material has been removed. This process is fuelled by three forces of nature, layering of hot/cold, gravity, and pressure difference, and takes approximately one hour.

Step 4. Customer product

The finished batch is stored and packaged for dispatch. The output is sponge iron: a non-pyrophoric, high-grade metal that can be used in steel or other metal fabrication processes. The outgoing metals are CO₂-free and can be used in electric arc furnaces, smelting plants, foundries, as well as cooling material in converters in the steelmaking process.

What Makes GreenIron’s Technology Different/?

Hydrogen-based reduction

Hydrogen enables fossil-free reduction while producing only water as a by-product, unlike traditional blast furnace processes that rely on coke and emit CO₂.

Batch-based flexibility

The batch-based process allows different materials and compositions to be processed within the same system, providing high operational flexibility.

Modular furnace design

Each GreenIron furnace has a small footprint and is designed for modular deployment, enabling:

• Local processing close to steel plants
• Stepwise, scalable expansion

Resilient operation

The process can operate effectively with intermittent power, making it well suited for integration with renewable energy systems.

Materials and Flexibility

GreenIron’s technology can process a wide range of metal oxides and residual materials, including:

• Iron-based residuals e.g. mill scale and filter dust (ev. länka till hur dessa material uppstår)
• Oxides containing nickel, copper and molybdenum

The near-term focus is on steel industry by-products, with the technology designed to expand into additional segments over time.

Validation and Industrial Readiness

GreenIron’s technology has been validated through extensive R&D and industrial development:

• Patented process and system design
• R&D furnace in operation since 2020
• First full-scale commercial facility in Sandviken, Sweden since 2025.