Metallurgy has always been a major industry in terms of industrial gas usage. The role of process gases has developed from their use as part of the combustion process to their use in atmosphere control and as part of chemical reactions.
Integrated Steel Mills
Since there are different specifications for O2 and N2 for blast furnaces and BOFs, AIR LIQUIDE has successfully developed specific cryogenic plants to meet your needs such as:
• Dual-purity plants,
• Low pressure / low purity plant for blast furnace air enrichment: OXIAL
It is generally used to prevent contact, hence interaction, between liquid metal and the surrounding atmosphere. Applications include melt stirring, tun dish purging to prevent steel re-oxidation and secondary steel refining in vacuum degassers, such as the VOD, RH, RH-OB. However, the largest quantities of argon are consumed in the AOD process for decarburising raw high-chromium steels while minimizing the chromium oxidation.
CO2 is typically used for environment protection. CO2 is used for red fume suppression during hot metal transfers, for nitrogen pick-up reduction during EAF tapping and for bottom stirring. In the non ferrous metallurgy, it is used for fume suppression during ladle transfer of matte (Cu/Ni production) or bullion (Zn/Pb production). Small amount of liquid CO2 can be used in processes incorporating carbon dioxide pre-treatment to enhance restoration of acidified water from Acid Mine Drainage (AMD).