Coke and Ironmaking

The process involved behind the blast furnace was very simple. The necessities used for the production of the pig iron were iron ore, coke, and limestone. For fuel for the blast furnace coke was used. The limestone was used as an additional source of carbon monoxide, which produces a chemical reaction with the iron ore. The coke, iron ore, and limestone are all dropped into the furnace from a giant mixing silo in to the bosh where extremely hot air passes through it heating it to melt all substances. The gases that are produced from the melted substances are caught in a chamber in the top of the furnace and then put in an exhaust chamber. When the substances are melted they separate into slag which floats up to the top, and then the full molten iron ore melts into pig iron. The giant tank that was made of firebrick was called a bosh, this is where the substances are melted. Close to the bottom of the bosh is a hole used in the draining of the molten pig iron. Near the top of the bosh is a hole where the scrap metal is taken off the top of the molten pig iron, this is called slag. The entire process involved with the blast furnace is very simple, and very productive. The two chief fuels used for the blast furnace are limestone and coke. Limestone contained large amounts of calcium carbonate and magnesium carbonate, or dolomite. Calcium carbonate was obtained as a white precipitate by passing Carbon Dioxide through lime water. Calcium carbonate's main purpose was for metallurgy. Coke is mostly made up of carbon and is made from coal by heating Amorphous Carbon to high temperatures without air. The main reason that these two fuels were used was because they both have large amounts of carbon in them, and they were cheap and easy to obtain. The carbon allowed the coke and limestone to be burned very freely and easily. There's an abundance of limestone, and the transition from coal to coke was not a difficult one. With the invention of the blast furnace, and efficient ways to heat it, comes the ability to quickly make pig iron. The problem with pig iron is that it is too brittle, and will not hold up to pressure. In order to solve this problem most of the carbon has to be extracted from the iron. After de-carbonization wrought iron is formed, "An easily welded and forged iron that is a mechanical mixture of refined metallic iron" In the early eighteenth century the process was done by re-heating the metal several times in charcoal fire, then banging away at it with big hammers. The result was an imperfectly formed but stronger metal. Henry Cort understood that age old process was a greatly inefficient method to form wrought iron, so he went to work and solved this problem by patenting grooved rolls and puddling in 1783 and 1784. This process de-carbonized the pig iron in one step. The metal was heated and cooled until they could be separated by different melting points. The rolling mill was then used to squeeze the iron rather than beat it with hammers. This method was fifteen times faster and now an unlimited amount of shapes and sizes could be formed into a strong efficient wrought iron. Script by David Carver, Mack Mayo and Charles Smith