raakarauta

Raakarauta is a Finnish term that translates to "pig iron" in English. It refers to a semi-finished, high-carbon iron alloy produced by smelting iron ore with a reducing agent, typically coke, in a blast furnace. The process involves heating the iron ore, coke, and a flux material such as limestone to very high temperatures. The coke acts as both a fuel and a reducing agent, removing oxygen from the iron oxides in the ore. The flux combines with impurities in the ore to form slag, which floats on top of the molten iron and can be easily removed.

The resulting molten metal, raakarauta, has a high carbon content, typically ranging from 3.5% to 4.5%, along with other impurities like silicon, manganese, phosphorus, and sulfur. This high carbon content makes raakarauta brittle and unsuitable for direct use in most applications. It is characterized by its granular fracture surface, giving it the name "pig iron" due to its resemblance to a sow nursing piglets, a casting method used historically.

Raakarauta serves as a primary raw material for further refining processes. It is typically remelted and recast into steel or cast iron. Steelmaking involves reducing the carbon content and removing impurities. Cast iron is produced by further alloying or by remelting and pouring into molds. Therefore, raakarauta is a crucial intermediate product in the iron and steel industry, forming the basis for a wide range of metallic products.