solid waste 101

Metal recycling, by Erik Hersman


Metals in the municipal waste stream fall into two categories: ferrous metals and non-ferrous metals. Ferrous metals are alloys of iron and one or more other metals, and have magnetic properties. Steel, alloy steel, cast iron, and wrought iron are common examples of ferrous metals. Non-ferrous metals do not contain iron. Aluminum, copper, brass, zinc, nickel, and tin and their alloys fall into this category. All metals can be recycled an infinite number of times without losing quality. The earth’s supply of metal ores is limited and mining these ores is energy intensive and produces toxic wastes. Recycling metal items saves energy and natural resources and reduces air and water pollution.

Food and beverage containers are the most common metal items in the municipal waste stream. Aluminum beverage cans, foil, and disposable baking pans are typical items in household trash. Most recovered aluminum is used in the production of new cans, which requires only 5% of the energy needed to produce cans from virgin aluminum ore. Each ton of aluminum that is recycled saves 10 cubic yard of landfill space. Steel and tin are typically used for canned foods. Steel is easy to separate from the waste stream because of its magnetic properties. Recycled steel is important in the production of new steel products, and the energy conserved by recycling a single steel food can could light a 10-watt LED bulb for more than a day. About half of the tin used annually is made into solder, and 12% into food cans and other packaging.  Recycled tin contributes approximately a third of the tin used in manufacturing annually.

Scrap yards handle large metal items such as appliances (“white goods”), left-over building materials, and vehicle parts.

Because of their high intrinsic value, metals such as lead, copper, silver, brass, and gold, are unlikely to enter the waste stream. “Heavy metals,” which include lead, cadmium, chromium, and mercury, are highly toxic and have serious health and environmental impacts. Items containing these metals should be disposed of with household hazardous waste.


Metal Recycling: How to Recycle Metal and its Importance (Conserve Energy Future)

Recycling Economic Information (REI) Report (EPA)

Aluminum Facts (Muncie Sanitary District)

Sustainability in Steel Recycling (American Iron and Steel Institute – pdf file download)

Tin Recycling (International Tin Association)

Infinitely Recyclable (The Aluminum Association)


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