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Material World
Object

Aluminium beverage can

Half a gram of metal thinner than a hair holding three atmospheres, and the most successful recycling loop there is.

A drinks can is drawn and wall-ironed from a single aluminium disc into a seamless body with walls around a tenth of a millimetre thick — thinner than a human hair, holding perhaps three atmospheres of carbonation, and stackable to several times its own weight.

It is two alloys and not one, which is the detail that decides its recycling. The body is a 3000-series aluminium-manganese alloy drawn to that thinness; the lid must be stiff enough to hold a rivet and a scored opening tab, and is a 5000-series aluminium-magnesium alloy. Melting cans together produces something that is neither, which is why closed-loop can recycling depends on collecting cans as cans rather than as scrap aluminium.

History

Steel cans from 1935; aluminium from 1958 and dominant within two decades on weight and on not imparting a taste. The stay-on tab of 1975 replaced the pull-ring, which had been discarded by the roadside in enormous numbers and cut a great many feet.

The weight has fallen continuously: a can that weighed around 85 grams in 1959 weighs under 13 grams now, which is a fifteen-fold materials efficiency gain achieved almost entirely through forming and alloy development rather than through any new material.

Cultural significance

It is the object that made aluminium recycling ordinary, and the economics are unusually favourable: remelting uses roughly five per cent of the energy of primary production, the metal does not degrade, and a can can be back on a shelf within weeks.

That combination — a valuable material, a clean single-product stream, and a consumer who already sorts it — is why can recycling rates reach eighty per cent and above in some countries while most other packaging does not come close. It is worth being precise about why: the loop closes because of the collection system, not because of the metal.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

is made of

  • Aluminium — element · the body drawn to a tenth of a millimetre, and a different alloy in the lid
  • 5000 series aluminium alloy — alloy · the lid, which must be stiff enough to hold a rivet and a scored tab where the body must be drawable

is used as

  • Packaging — application · and the closed loop works because of the collection system rather than because of the metal

Sources

  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
  • Material World
    Our own writing

Questions this page answers

Where it comes from, and what it becomes

Follow Aluminium beverage can back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Upstream — what it comes from

  • Aluminium beverage can → is made of (the body drawn to a tenth of a millimetre, and a different alloy in the lid) → Aluminium → is extracted from (via alumina — bauxite is refined by the Bayer process before smelting) → Bauxite → is sourced from (the residue of prolonged tropical weathering, which strips the silica and alkalis out of an aluminosilicate rock and leaves the aluminium behind — basalt is one common parent among several) → Basalt → is sourced from (partial melting of mantle peridotite is what basalt magma is — the residue left behind stays peridotite, depleted of what went into the melt) → Peridotite → is composed of (the mineral that defines the rock and gives it its name — a peridotite is olivine-dominant by definition) → Olivine
  • Aluminium beverage can → is made of (the lid, which must be stiff enough to hold a rivet and a scored tab where the body must be drawable) → 5000 series aluminium alloy → is produced by (magnesium into aluminium, and it must be melted under cover because magnesium burns) → Alloying and melting → takes as input (the base metal of both brass and bronze) → Copper → is produced by (as blister copper, refined electrolytically afterwards) → Smelting → takes as input (roasted to drive off sulfur, then reduced to copper) → Chalcopyrite
  • Aluminium beverage can → is made of (the body drawn to a tenth of a millimetre, and a different alloy in the lid) → Aluminium → is produced by (collects at the cathode while the carbon anodes are consumed) → Hall–Héroult process → takes as input (dissolved in molten cryolite and electrolysed) → Aluminium oxide → is sourced from (dissolved out with hot caustic soda in the Bayer process) → Bauxite → is sourced from (the residue of prolonged tropical weathering, which strips the silica and alkalis out of an aluminosilicate rock and leaves the aluminium behind — basalt is one common parent among several) → Basalt
  • Aluminium beverage can → is made of (the body drawn to a tenth of a millimetre, and a different alloy in the lid) → Aluminium → is extracted from (via alumina — bauxite is refined by the Bayer process before smelting) → Bauxite → is sourced from (the residue of prolonged tropical weathering, which strips the silica and alkalis out of an aluminosilicate rock and leaves the aluminium behind — basalt is one common parent among several) → Basalt → is composed of (an early-crystallising constituent of basaltic magma) → Olivine
  • Aluminium beverage can → is made of (the body drawn to a tenth of a millimetre, and a different alloy in the lid) → Aluminium → is extracted from (via alumina — bauxite is refined by the Bayer process before smelting) → Bauxite → is sourced from (the residue of prolonged tropical weathering, which strips the silica and alkalis out of an aluminosilicate rock and leaves the aluminium behind — basalt is one common parent among several) → Basalt → is composed of (calcium-rich plagioclase is a defining constituent of basalt) → Plagioclase
  • Aluminium beverage can → is made of (the body drawn to a tenth of a millimetre, and a different alloy in the lid) → Aluminium → is extracted from (via alumina — bauxite is refined by the Bayer process before smelting) → Bauxite → is sourced from (the residue of prolonged tropical weathering, which strips the silica and alkalis out of an aluminosilicate rock and leaves the aluminium behind — basalt is one common parent among several) → Basalt → is composed of (carried up as xenocrysts in alkali basalt and recovered from the gravels the basalt weathers into, rather than mined from the rock itself) → Sapphire

These are the most distinct paths back. Aluminium beverage can can be traced through others besides.

Downstream — what it becomes