The input materials arrive to our plant. These are oxidised materials and can have different shapes and metal content, such as: Ore, slag, mill/oxide scales, filter dust, roasted pyrite, grinding swarf, various tailings, etc.
The input material is agglomerated. To do so, in connection to our reduction furnace there is a pelletising/briquetting machine which use binders to agglomerate the material using for instance 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 allow the process gases flow freely through the batch to the heat recovery system. The batch is pre-heated to minimize process time and energy consumption. This can be achieved circularly by using excess heat from the previous process cycle.
The batch is placed in the bell furnace when it has reached the desired temperature: approximately 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 including elimination of the oxygen gas (O2). Hot hydrogen gas (H2) is then introduced into the chamber and the reduction process starts.
Steam (H2O) is created in an endothermic (heat-consuming) process, which decreases the temperature. The endothermic qualities results in steam being colder than the surrounding atmosphere and is subsequently “layered down” in a hot/cold separation. The steam is also 9 times heavier than hydrogen as thus pulled down by gravity. The steam is condensed to water as it cools down from heating the cold incoming hydrogen. The volume of steam is over a thousand times greater compared to water a droplet. As the steam condenses below the reduction chamber, a relative low pressure is created below the reduction chamber portion of the furnace. Nature will strive to equalise pressure within the furnace solution thus increasing the flow of hydrogen through the bed of oxidised material which in turn will speed up the reduction process. The only by-product of the process – water will continue to form until all available oxygen in the material has been removed. This process, fuelled by three natural laws (layering of cold/hot, gravity and pressure differences) takes approximately one hour.
The finished batch is stored and packeted for dispatch. The output is a non-pyrophoric high-grade metal (for instance sponge-iron) that can be reintroduced into the steel or other metal making processes. The product is CO2– and fossil-free and can be used in electric arc furnaces or foundries, as well as cooling material in converters in the steelmaking process.