1.18 : 강철 제조

Steel manufacturing begins with smelting iron ore into cast iron in the blast furnace. Smelting involves layering the iron ore with a fuel called coke and crushed limestone in the furnace.

First, coke is ignited with a blast of air, producing carbon monoxide, which reduces the ore to molten iron.

The limestone forms a slag, capturing impurities, and floats above the molten metal. This molten iron is then drained for steel processing.

The molten iron contains excess carbon and impurities. A basic oxygen process is adopted to remove them. It involves an oxygen lance dipped into molten iron and scrap, using a lime and fluorspar flux, which forms discardable slag by reacting with phosphorus.

Finally, new metallic elements may be introduced to modify the steel's composition as required.

When steel reaches the pouring stage from the furnace, it's either molded into ingots or processed via a strand-casting machine. Ingot molds may have diameters spanning several feet and heights ranging from six to eight feet.

Also, the finished steel is continuously cast into thick, rough shapes known as beam blanks or blooms.