Pig iron is made by combining iron ore, charcoal, and flux in a blast furnace. The materials undergo reactions, creating liquid pig iron that drains through the bottom. Cast iron is produced by cooling the liquid iron in a long central channel. Pig iron is an intermediate step in creating wrought iron, cast iron, or steel.
The process of making pig iron involves combining iron ore, charcoal, and an intermediate material known as flux inside a blast furnace. As the materials combine with the intense heat, much of the iron ore melts, creating a superheated liquid form. Depending on the materials and method of cooling used, making cast iron can be an intermediate step in creating wrought iron, cast iron, or steel.
A blast furnace used to produce pig iron is usually a large steel structure with several openings. Near the top, openings allow for the addition of the ore, charcoal, and flux materials in an alternating pattern. Further down the furnace, two doors allow for the injection of air, which is preheated to a temperature between 1472-2192 degrees Fahrenheit (800-1200 degrees Celsius). At the bottom of the blast furnace, two additional openings allow the liquid metal and slag to drain.
Once inside the furnace, the materials undergo several reactions which allow for the creation of liquid pig iron. Coal releases carbon monoxide, which amplifies the heat in the air, raising the temperature to even higher levels. As carbon monoxide increases, it reduces the amount of iron oxide in the iron layers, leaving a higher percentage of pure metallic iron and reducing the melting point of the ore. The flux material, which is usually limestone or feldspar, reacts with impurities in the iron ore, creating a low-melting material known as slag and further purifying the ore. Once these crucial interactions have occurred, the iron melts and drains through the bottom of the furnace.
The next step in the production of cast iron involves cooling the material and also explains the unusual name of the product. As the liquid iron flows out of the furnace, it is traditionally diverted into a long central channel with many shorter channels arranged at an angle, where it cools and hardens. The name “ghisa” derives from the resemblance of the long canal to a mother pig, and the smaller canals to suckling piglets. In most modern cast iron production, however, this process is no longer used, as methods have been developed that allow cast iron to be transported in a liquid state, rather than as a hard material.
The production of pig iron is generally only one step in creating a finished iron product, as the high carbon content of iron in this form renders it mostly unusable. To make it more versatile, it can be smelted again and mixed with slag, creating wrought iron, or combined with additional iron ore and alloys to create pig iron. Most often, the production of pig iron is an intermediate step on the road to making the steel, involving a second burning process to remove many of the remaining impurities and the addition of other metals to create an iron-based alloy.
Protect your devices with Threat Protection by NordVPN
