Vacuum Treatment of Molten Steel: RH (Ruhrstahl Heraeus) versus VTD (Vacuum Tank Degasser)

摘要

In the beginning of their development in 1950s, RH and VTD were applied to produce quality steel in term of low hydrogen content for reducing of "hair crack" formation. In the meantime, both of these technologies are installed in steelworks in order to obtain high quality of steel products containing low hydrogen content, low nitrogen content, ultra-low carbon content, low total oxygen content as well as ultra-low sulphur content. The criteria of technology selection of these vacuum treatment techniques are strictly dictated by the steel grade to be produced. Intensive slag-metal interaction was observed during molten steel treatment on VTD which promotes a good condition for sulphur removal. On the other hand, less slag-metal interaction is taken place during RH treatment. Therefore, comparisons of RH and VTD treatments for impurities removal in molten steel are presented in this paper using some models for impurities prediction after vacuum treatment, consumptions and treatment cycle times, as well the availability of the vacuum vessel. The capability of molten steel desulphurization on VTD plant through top slag and on RH plant by powder blowing is discussed.