Steelmaking

Pig Iron and/or Steel scrap is used as a starting Material for smelting steel. In addition to carbon, this includes admixtures of other Metals and non-metals. Oxygen is added to the molten metal to lower any Carbon content that is too high and remove undesirable accompanying elements (impurities). This oxidises these elements into slag and burns the carbon. Since large amounts of heat are generated during this process, iron and steel scrap needs to be added to prevent overheating.

Basic oxygen steelmaking processes such as the Linz-Donawitz (LD) process or the further developed LD-AC process have become the most widely established on a global level.

EF steelmaking is used to make high-quality electric steels. An electric arc generates temperatures of up to 3,500°C in the furnace. Scrap, pig iron and the required quantities of alloying elements are added after refining the molten metal. Deoxidising with Aluminium or ferrosilicon can improve the quality of the steel.

Depending on the extent of deoxidising, killed or unkilled steels are produced. Only small quantities of gases are still found in the latter. Even smaller residual gas fractions can be achieved using vacuum remelting, which produces the highest grade steel.

Smaller batches are often smelted in induction furnaces. An alternating magnetic field is built up in an induction coil in the crucible. When combined with the molten metal, this creates a short-circuited coil. The induced voltage heats the material.