Profiles in Garbage: Steel Cans

Steel containers may have originated in 14th century Bohemia. However, it wasn't until 1809 that a Frenchman invented a process to package preserved food. Three years later, tinplated cans were produced in Britain and perfected during the next four decades. And, in 1938 the steel beer can was first produced.

Steel cans are made from tinplated steel, which is produced in basic oxygen furnaces. A thin layer of tin is applied to the can's inner and outer surfaces to prevent rusting and to protect food and beverage flavors. As a result, steel cans are often called "tin cans." As steel-making has evolved, an increasing amount of cans use a chromium wash in place of tin.

Most steel cans are used for food products (steel cans account for more than 90 percent of food cans), followed by "general packaging" for products such as paint and aerosols.

Steel Can Municipal Solid Waste (MSW) Facts:

Generated: * 2.86 million tons or 1.3% by weight.*

* 21.4 pounds of steel cans per person.*

* 32.8 billion steel cans, or 122 per person, were used in 1997.

* The average steel can weighs 2.78 ounces.

Recycled: * 1.73 million tons for a 60.5% recycling rate.*

* 1.5 million tons for a 57.9% rate in 1999 (industry data).

Recycled Content: The basic oxygen furnace process uses a minimum of 25% scrap steel to make tinplate and other steel products. Steel cans provide less than 10% of this scrap.

Composted: * Steel cans do not compost. However, they are biodegradable in the sense that steel cans left exposed to the elements will slowly rust.

Incinerated or Landfilled: * 1.13 million tons or 0.7% of discarded MSW by weight.*

* Steel cans are noncombustible.

* Waste-to-energy facilities will normally use magnets to remove steel cans from incineration.

Landfill Volume: * 4.03 million cubic yards or 1% of landfilled MSW.*

Density: * Whole, unflattened steel cans have a density of 150 pounds per cubic yard.

* Baled cans have a density of 850 pounds per cubic yard.

* Landfilled steel cans weigh 560 pounds per cubic yard.

Source Reduction: * Today's steel cans are 34% lighter in weight than in 1972.

* During the past 25 years, average tinplate thickness has been reduced by 30 percent, from 0.20 mm to 0.14mm.

Recycling Markets:

Steel mills are the largest market for steel cans. Integrated mills use the basic oxygen process to manufacture tinplate, appliances, car bodies and steel framing.

Electric arc furnaces use 100% scrap to produce steel shapes such as railroad ties and bridge spans. Electric arc furnaces are more geographically diverse and tend to have smaller capacities than basic oxygen furnaces.

Detinners remove the tin from steel cans for resale to tin using industries. With less tin use in steel cans, the importance of the detinning market has declined substantially. Foundries use scrap as a raw material in making castings and molds for industrial users.

End-Market Specifications:

Steel cans are covered by Institute of Scrap Recycling Industries Inc. Ferrous Scrap Guidelines FS 213, "Steel Can Bundles." Cans may be baled without removal of paper labels, but must be free of other non-metallics. Non-ferrous metals and large pieces of plastic that were not eliminated at processing facilities can create safety and production problems in a steel furnace.

Recycling Cost and Value: * Collection costs range from $217 to $309 per ton.

* Processing costs range from $30.22 to $125.64 per ton.

American Iron & Steel Institute, Washington, D.C. Website: www.steel. org

Can Manufacturers Institute, Washington, D.C.

"Characterization of Municipal Solid Waste in the United States: 1998 Update," 1999. U.S.

Environmental Protection Agency Office of Solid Waste, Website:

"Measurement Standards and Reporting Guidelines," National Recycling Coalition, Alexandria, Va. Website:

Resource Recycling Technologies, Vestal, N.Y."Scrap Specifications Circular," 1998, Institute of Scrap Recycling Industries Inc., Washington, D.C. Website:

Steel Recycling Institute, Pittsburgh. Website:

Waste Recyclers Council, Washington, D.C. Website: www.envasns. org * 1997 U.S. EPA estimates.