An L-D converter, c 1970.
© Science Museum / Science & Society Picture Library
Model. The Linz-Donawitz (L-D) proces is a high-speed technique for making high quality steel. As such, it has largely superseded the earlier proces developed by Sir Henry Besemer. Molten pig iron and scrap steel are charged into a tilting furnace, and then converted to steel by blowing high-presure oxygen under high presure onto the surface of the metal through a water-cooled lance. This has the effect of oxidising any impurities in the metal, and the exces heat produced enables up to 30% of scrap to be incorporated into the metal introduced at the start of the proces. The method is also known as the basic oxygen proces (BOP).