D stands for the good standard mass production

The current standard solution in the industry for the mass production of primary steel is based on the blast furnace route.  Due to many differences in the details of the processes, the emissions per blast furnace vary. For new and modern blast furnaces, class D applies with 1,800 to 2,250 kg CO₂e per tonne of crude steel at 20% scrap ratio. Process optimisation with regard to CO₂-emissions is achieved, for example, by adding high-purity scrap and hydrogen to the blast furnace process. In addition, further scrap is traditionally used for cooling in the converter process. Some manufacturers project these savings onto a smaller product quantity in a special "mass balancing process" so that optimised products can be offered in a targeted manner. Older or technically unfavourable blast furnaces can cause emissions of > 2,250 kg CO₂e per tonne of crude steel. This corresponds to class E on the Les standard scale. The class is not labelled.

Iron ore is reduced to pig iron using coking coal in the blast furnace process. The smelting process takes place at around 2,000°C. In the subsequent steelworks, crude steel is produced in the converter by blowing in oxygen. Scrap is also fed in for cooling. Slabs are then cast and rolled out in the hot rolling mill. The flat steel can also be further refined using a cold rolling process and technical surface treatments.

The blast furnace process emits large quantities of CO₂, which is the most serious climate disadvantage of this process. Additional blast furnace gases from the process are then converted into electricity, meaning that many integrated steelworks have to buy little or no external electricity. This circumstance additionally drives the demand for energy in the transformation of the steel industry. Electricity has to be purchased on a large scale and channelled to the steelworks via an infrastructure if self-supply is no longer possible.

The label:

The label makes the various solutions offered by steel manufacturers transparent. The focus is on the basic product with the highest emissions, namely from the raw material through crude steel production to the hot-rolled coil. To this end, Stahlo has developed a combined label that expands the Low Emission Steel Standard (Less) of the German Steel Federation with additional information on the main elements of the process. This gives Stahlo customers the transparency and comparability of the Less classification as well as further information about the "HOW" of the manufacturer. The various elements of production are represented by simple symbols.