Basic oxygen furnace (postwar Austria)

Supersonic-velocity pure-oxygen lance creates froth of steel; 300 tons of cast iron converted to steel in 20 minutes vs. 24 hours in basic open hearth. The shaving-cream-vs-surface-diffusion analogy.

Then some guys in Europe, in Austria, decided to go back to something similar to the Bessemer converter. They would have a huge vessel four or five stories tall, steel lined with ceramic so you can melt steel in it without melting the steel shell. You have a massive steel pot maybe three or four feet deep. You pour the hot cast iron in here, and then you bring in a lance, a water-cooled copper lance, maybe about three-quarters of a foot in diameter, and you blow at supersonic velocity pure liquid oxygen down. That creates a froth of steel. They will fill up a 700-ton vessel — and in 20 minutes you can do what took 24 hours in a basic open hearth. The basic open hearth was surface diffusion. It was air going across the surface. You had to transport that carbon to oxygen one way, the carbon dioxide the other way — slow process, low area of contact, a surface reaction. Over here it's like shaving cream. You've got lots of surface area. And it's pure oxygen — you don't have to add any heat, you're burning carbon in there. In 20 minutes, 300 tons of cast iron becomes 300 tons of steel.