Metallurgical results from a 30‐t AC plasma ladle furnace

In a 30‐t ladle furnace equipped with three A.C. transferred arc‐plasma torches for a power input of 6 MW, the influence of argon plasma heating on the chemical composition of a number of steel grades from carbon to chromium‐nickel steels was investigated. The concentrations of carbon, manganese, chromium and nickel remained virtually constant even for extra‐long heating periods of 2 hours. Silicon melting loss was appr. 0.03%/h, comparable to conventional ladle furnaces. Nitrogen pickup proved to be negligibly small, although the N 2 partial pressure in the furnace was about 0.5 bar. Since the slag is well heated up by the plasma flames, a metal desulphurization is noticed, the extent of which depends on the basicity of the slag. At the slag/gas interface, equilibrium is established with the slightly oxidizing furnace atmosphere, leading to sulphur transfer from slag to gas via SO 2 .