The Ruhrstahl-Heraeus process (RH process) is a secondary metallurgy process in which liquid metal - especially steel - is subjected to a vacuum treatment for degassing . In addition, the melt can also be decarburized. It is named after the two companies that developed the process in the late 1950s: Ruhrstahl and Heraeus .
A portion (approx. 25%) of the liquid steel in the ladle is sucked into a vessel under vacuum . The vessel has two immersion tubes on the underside. These are dipped from above into the melt located in a melting pan, then the vessel is evacuated . As a result, part of the melt rises through both channels into the vessel. One therefore speaks of a partial quantity degassing system. Argon or nitrogen is then continuously blown into one channel . Since nitrogen is considerably cheaper to buy, argon is usually only blown in if the batch to be treated must not contain any additional nitrogen. This causes the liquid steel to rise into the vacuum vessel in this channel, following the principle of the mammoth pump . There the melt is decarburized and degassed and flows back through the other channel into the melting pan. This is why one speaks of the vacuum circulation process.
The aim of this treatment is to produce steel with greater purity, in particular the removal of hydrogen in order to reduce hydrogen brittleness. The first RH treatment of steel was carried out in the Henrichshütte steelworks on June 24, 1958. The RH process was later expanded to become the RH-OB process (RH-Oxygen Blowing), in which the degassed melt is also decarburized directly with blown oxygen. In addition to steel, the process can also be used for other metals such as B. Apply copper .
- Application / patent DE1216904A and DE1098971B "Method / device for vacuum degassing of molten metals, especially steel" from April 3, 1957 and May 30, 1958
- Franz-Josef Hahn, Ingo Knopp, Andreas Ploch, Carl-Heinz Schutz: A success story: The RH vacuum process after 50 years of development . In: Stahl und Eisen 128, 2008, 11, , pp. 61-76.