PROCESS DESCRIPTION

During production of steel in a blast furnace, the molten pig iron goes to the converter for refining immediately after melting. The converter is a large mounted container which is tiltable. In the converter, pure oxygen is blown onto the molten pig iron under a pressure of approximately 12 to 14 bar and burns carbon to carbon monoxide (decarburisation) in an intensive, exothermic reaction. Other elements, such as silicon, manganese or sulphur, also oxidise and settle in the slag.  

After decarburisation, reduction of slag chromium and, if necessary, desulphurisation is carried out before the final temperature and alloy are set. In order to achieve maximum decarburisation and minimal slagging as well as for the degassing of hydrogen, argon or an argon-oxygen mixture, the composition of which is changed during the process, is supplied via floor purgers.

For the slag-splashing process, a slag residue remains in the converter after pouring off the molten steel. Nitrogen is injected through an oxygen-blowing lance and as a result the slag is distributed over the inner surface of the converter and forms a protective layer on the refractory lining, which significantly prolongs its life.

Advantages:

• Maximum decarburisation
• Optimal slagging and hydrogen degassing
• Protects refractory lining
• New refractory lined converters must be warmed up according to the specifications of the refractory material producer. Oxyfuel burners, with air enrichment or exhaust gas recirculation in the lower temperature range, are an economical solution for this.

Advantages:

• Natural gas savings of 30% - 40%