Process engineering and cost efficiency of steelmaking by means of hydrogen-based direct reduction.

Objective. Sponge iron is also gaining in importance in Europe because scrap-based steelmaking requires the level of tramp elements to be kept within narrow limits, especially when producing flat steels on thin slab casters in mini-mills. Examined is the extent to which liquid steel can be produced economically in Europe by way of the hydrogen-based direct-reduction/electric steelmaking route, also taking into account the reduction of ore fines. Primarily of interest is whether the production costs are comparable to those incurred via the blast furnace/LD steel plant route. Summary. Some 480 x 10(9) m(3) (S.P.T.) hydrogen are produced per year around the world, of which around 42% stems from natural gas, 21% from oil, and 21% from coal or coke-oven gas. The link between hydrogen and steelmaking is made in the present article through two direct reduction processes: the Hyl III process which uses pellets and lump ore, and a new process designed to reduce ore fines in a horizontal fluidized-bed reactor. In the latter process a heat exchanger, through which a part of the heat required for the reduction is generated, is immersed in the fluidized bed. A cost comparison between the blast furnace/smelting reduction plant/LD steel plant route and the direct reduction plant/electric steel plant route when making 1 to 1.5 mill. tpa steel illustrates that the production of DRI can also be quite attractive in Germany. A prerequisite would be the hydrogen-based reduction of ore fines, in which respect the hydrogen would have to extracted from cheap imported coal. Based on a production capacity of 3 to 4 mill. tpa., the prime costs of making liquid steel by either route are approximately the same. It is shown that sponge iron (DRI) produced in Germany can be the same in price or also be less expensive than sponge iron imported to Germany from ''cheap energy countries''. The CO2 emission levels per tome of liquid steel are calculated to be lower for the ore fines reduction/electric steelmaking route than for conventional steelmaking in a blast furnace and LD steel plant.