Metal recycling conserves natural resources and significantly reduces the energy footprint of manufacturing. Metals are highly valued because they can be melted down and reformed repeatedly without any degradation to their fundamental properties, making them infinitely recyclable. This conservation process lessens the demand for resource-intensive mining operations and the substantial energy required for primary material production.
The Two Core Categories of Recyclable Metals
The initial stage of metal recycling relies on the presence of iron. All recyclable metals fall into one of two categories: ferrous or non-ferrous. Ferrous metals, such as steel and iron, contain iron, which makes them magnetic and generally susceptible to rust when exposed to moisture. Their magnetic property simplifies the separation process, allowing recycling facilities to use powerful electromagnets to easily extract them from mixed waste streams.
Non-ferrous metals do not contain iron and are consequently non-magnetic. This group includes materials like aluminum, copper, brass, and zinc, which possess a higher resistance to corrosion. Because magnets cannot be used to separate non-ferrous metals, specialized technology known as eddy current separators is employed. This equipment uses a rapidly changing magnetic field to induce an electric current within the non-magnetic metals, causing them to be momentarily repelled and sorted into a separate collection stream.
Highly Recycled Metals Found in the Home
The most commonly recycled metals that consumers encounter are those found in everyday household packaging, primarily aluminum and steel cans. Aluminum beverage cans are highly sought after because recycling requires approximately 95% less energy than producing new aluminum from its raw ore, bauxite, substantially reducing greenhouse gas emissions.
Steel cans, often referred to as tin cans, are also widely accepted in curbside programs. Recycling steel saves between 60% and 74% of the energy needed for new production, conserving iron ore, coal, and limestone. For both aluminum and steel food containers, proper preparation is necessary to maintain the quality of the recycled material. Removing all food residue by rinsing the cans prevents contamination that can negatively impact the smelting process and the final product purity.
High-Value Scrap Metals and Alloys
Beyond curbside collection, certain metals and alloys hold significant economic value and are collected at dedicated scrap yards. Copper is consistently one of the most valuable non-ferrous metals, driven by its widespread use in electrical wiring, plumbing pipes, and heat exchangers. Its high market price provides a strong incentive for individuals and businesses to collect and sell it for scrap rather than disposing of it as trash.
Brass, an alloy primarily composed of copper and zinc, is another high-value scrap metal commonly sourced from plumbing fixtures, keys, and decorative hardware. Scrap facilities also process large volumes of stainless steel, a ferrous alloy known for its corrosion resistance and found in appliances and industrial equipment. These materials are typically handled by demolition companies or individuals who collect larger, heavier items not suitable for municipal bins.
To maximize the value of these materials, scrap must be “cleaned” by separating the metal from any attached non-metal components. For example, plastic sheathing must be stripped from copper wiring before sale, as insulation reduces metal content and purity. Similarly, any steel screws or plastic handles must be removed from aluminum components to prevent contamination during the melting process. Clean, segregated scrap fetches the highest price because it requires less processing labor at the recycling facility.
Metals That Cannot Be Recycled Curbside
While most metal is recyclable, certain items are deliberately excluded from standard curbside programs due to safety hazards, contamination risks, or their complex composition. Items containing hazardous heavy metals, such as mercury in old thermometers or fluorescent bulbs and lead in certain batteries, must be kept out of the recycling stream. These toxic substances can be released during processing and require specialized hazardous waste or e-waste collection programs for safe handling.
Small, mixed-material metal items can damage sorting machinery at the materials recovery facility. Small metal pieces like screws, bolts, and thin wire hangers often fall through the sorting screens or wrap around rotating equipment, causing costly breakdowns. Similarly, small household appliances, despite containing metal, are problematic due to their mixture of plastic, wiring, and various metals that cannot be easily separated by the automated system.
Any large metal items that may be contaminated with oil, fuel, or chemical residues, such as car parts or machinery components, are universally rejected from bins. The residual fluids pose a fire risk and contaminate large batches of otherwise clean scrap metal. For these complex or contaminated materials, the appropriate disposal options are often municipal drop-off events, specialized electronic waste recyclers, or direct delivery to a commercial scrap metal yard.