The process to thermo-chemically melt-scalp flaws and impurities developed on the surface of the steel block by using fuel gas and oxygen to hold a high quality in steel material is called scarfing When Hot block  is scarfed it is termed as  HOT SCARFING or COLD SCARFING in case the material is a cold block.

This is a process called oxygen lancing. A pipe pumping pure oxygen is used to clear slag near the outlet of the smelter vessel, so that liquid iron can flow freely. A furnace is used during the smelting process - heating iron ores to extract iron. The mixture of iron and oxide impurities is heated to about 1,500°C. Molten iron is drawn off on one side, and slag (waste) on the other.