Hydrogen and nitrogen removal during converter steel making - by carbon di:oxide and oxygen injection through nozzles comprising three coaxial pipes

摘要

In a converter steel making process using bottom blowing nozzles which consist of three concentric tubes, oxygen is blown through the inner tube and protective gas is blown through the outer tube. The H2 and N2 contents of the metal are reduced at the end of refining by using CO2 as the protective gas. At the required moment for CO2 blowing, O2 is blown only through the inner tube and CO2 is blown through the intermediate tube and the outer tube. Large differences in amts. of gas to be injected can be accommodated, e.g. when C3H8 (used in amt. is approx. 4% of the amt. of O2) is replaced by CO2 (used in amt. is approx. 20% of the amt. of O2) as protective gas, since the outer tube only can be used for C3H8 blowing while bath the intermediate and outer tubes are used for CO2 blowing.