With so many of our everyday products and structures relying on the strength and durability of steel, understanding its creation will ensure a safer and more effective product. This starts with steel's production in a furnace. Two common types are the basic oxygen furnace and electric arc furnace varieties, but do you know the difference?
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What is a Basic Oxygen Furnace?
A basic oxygen furnace is a pear-shaped structure with a closed bottom and an open top that works to process steel. Commonly known as BOF, this type of furnace relies on pure oxygen, rather than air, to convert iron into steel.
Dipping a water-cooled oxygen lance into the top of the furnace, inputs such as iron ore and sometimes coal or limestone are added before poured into a ladle, where alloys and deoxidizers are added to in order to help it reach the proper composition. The shape of a basic oxygen furnace allows manufacturers to tilt it onto its side to charge and pour molten steel. On some rare occasions, oxygen is injected into the mixture through a process known as "bottom blowing," through a spout found at the bottom of the barrel.
What is an Electric Arc Furnace?
The electric arc furnace is more modern than the former and produces its product using scrap steel material, which is tossed into the furnace with the help of a large crane. A lid containing electrodes is then placed on top of and lowered into the furnace, where they conduct an electric current which takes the shape on an arc. As the heat created melts the scrap steel, additional metals and oxygen are added to the material and eventually poured into a ladle and removed from the furnace once the process is completed.
The Pros and Cons of Each
A basic oxygen furnace yields high production with minimal labor involved and creates a finished product that is low in nitrogen. The need for raw materials to create the end product, however, has proven to make this type of furnace inefficient both financially and in terms of its use of time. Moreover, when coal added during production is burned off, it creates a by-product known as coke, which gives off carbon monoxide, as does limestone, which is another common additive used in this method.
Because electric arc furnaces rely on mostly recycled materials to produce steel, the environmental factors alone are considered a major advantage. Using 100 percent recycled steel, electric arc furnaces help contribute less waste material and save primary resources and energy while lowering greenhouse gas emissions. Because this method relies so heavily on unwanted and unused material, however, the resources can be limited, stalling production time and output.