The waste materials combine with the limestone, which acts as a flux, forming a slag, which floats on top of the molten iron. Both are tapped in turn, the slag being removed in slag cars, and the iron in hot metal cars. Exhaust gases are carried away from the top of the blast furnace by the downcomer pipes, cooled, and the solid content removed in dust catchers. This dust contains iron ore, limestone, and coke, as well as waste products, and is normally recycled to the roasting and sintering area for reuse. Average output from a modern blast furnace will be approximately 800-1000 tons per day.
Iron produced in the blast furnace is carried to the steel making area in hot metal cars.
The Open Hearth 2. The Bessemer Converter 3. The Basic Oxygen Process 4. In each one the carbon content of iron is reduced to a required level by the application of heat. All ingredients are added during the process to effect the properties of the finished product, which is steel.