A converter steelmaking method in which molten iron is blown into steel from the top of a converter with pure oxygen, or LD method; in the United States, it is generally called BOF method, also called BOP method. It is the main method of modern steelmaking. The furnace is an upright, dome-shaped container that is inserted into the furnace from the top with an upright water-cooled lance to supply oxygen. The shaft can be tilted.