Steel is a versatile commodity that plays a major part in everyday life—it is used in applications ranging from food cans and household containers to automobiles and office buildings. Steel makes up the largest category of metals in the municipal solid waste (MSW) stream. For many years, steel has been a commonly recycled material in North America and throughout the world. Efficiently managing and recycling used steel products is important to maximize the utility of this commodity.
How Steel is Made
Steel is an alloy of iron, produced by heating coke, iron ore, and limestone in a blast furnace. It is produced in one of two ways: the basic oxygen furnace (BOF) process and the electric arc furnace (EAF) process.
The BOF process uses 25 to 35 percent recovered steel to make new steel. It combines molten iron from blast furnaces with an injection of very pure oxygen, which causes a chemical reaction. Products such as automotive fenders, refrigerator encasements, soup cans, pails, and industrial drums are made with this type of steel. BOF steel is ideal for these applications because of its "drawability," or ability to be flattened into sheets.
The EAF process uses virtually 100 percent recovered steel to make new steel. Scrap steel is melted and refined by passing an electric current from electrodes through the material. Products such as structural beams, steel plates, and reinforcement bars are made with this type of steel because it is so strong.
How Steel is Recycled
Steel cans from MSW and other steel recyclables are usually collected from the curbside, drop-off sites, or multi-material buyback centers. The steel is then hauled to a material recovery facility, where workers separate it from other recyclables and crush it in to large bales. The bales are shipped to steel mills or foundries, where they are combined with other steel scrap and melted in a furnace to make new steel.
Benefits of Steel Recycling
The steel industry in North America has been recycling steel scrap for more than 150 years. The steel industry needs scrap to produce new steel, which ensures that all steel products contain anywhere from 25 percent up to 100 percent recycled content. It also is cheaper to recycle steel than it is to mine virgin ore to manufacture new steel. New ore is still mined in order to supplement production of steel and steel products.
Recovering steel not only saves money, but also dramatically reduces energy consumption, compared to making steel from virgin materials. In turn, this reduces the amount of greenhouse gases released in to the air during processing and manufacturing steel from virgin ore.