Interest in our ground-breaking, CO2-free technology is increasing from the metal and mining industry around the world. We have therefore visualised the process in four steps – with associated descriptions – so that you can quickly and easily understand how GreenIron can contribute to the green transformation of our industry.
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.
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.
The batch is placed in the bell furnace when it has reached the desired temperature: around 550 °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.
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.