How much energy does aluminium recycling save?

Remelting aluminium from scrap takes a fraction of the energy needed to produce it from bauxite — industry figures usually put it in the order of a few per cent. Primary production is electrolysis with very high electricity demand, whereas recycling is, in simple terms, melting metal that already exists. That gap is the main reason aluminium scrap has real market value.

Can aluminium be remelted indefinitely?

The metal itself does not lose its properties when remelted, so the number of cycles is not the limit. The limit is alloy composition: if wrought material is mixed with casting material, the resulting alloy usually carries too much silicon and copper to return to wrought products. The metal stays in the loop, but it descends to less demanding applications.

Why do aluminium alloys have to be kept separate?

Because adding alloying elements is easy, while removing them from the melt is not realistically feasible at industrial scale. A batch of clean extrusion can come back as extrusion. The same mass mixed with castings, wheels and radiators ends up in casting alloys and is worth less — which is why we value separated streams higher.

Aluminium recycling in a closed loop: what actually closes it

Aluminium is the textbook example of a closed material loop, but the loop only closes when wrought alloys are kept apart from casting alloys. We explain alloy cascading and what decides whether an extrusion comes back as an extrusion.

Aluminium is the most frequently cited example of a closed material loop — and rightly so, because the gap between primary production and recycling is dramatic here. Producing aluminium from bauxite is electrolysis with enormous electricity demand; remelting finished metal is, in simple terms, melting it. Industry figures usually put recycling in the order of a few per cent of the energy required for primary production.

That, however, is only half the picture. The "extrusion comes back as extrusion" loop does not close by itself — it is closed by keeping alloys apart. This article explains why.

A closed loop versus a cascading loop

In a closed loop the product returns to the same application: a window profile remelted into an extrusion billet becomes a profile again. In a cascading loop the metal stays in the economy but descends to less demanding applications — and does not come back up from them.

Aluminium is capable of both. Which of the two happens is decided by the composition of the batch that enters the melt.

Why alloys do not travel back up

Wrought aluminium (profiles, sheet, strip) and casting aluminium (housings, wheels, engine components) differ in their additions — above all silicon and copper. Casting alloys carry considerably more of both, because they need fluidity.

The problem is asymmetric: adding an alloying element to the melt is easy, removing it is practically impossible. So if extrusion is mixed with castings, the resulting alloy has a composition suited to foundry work but not to extrusion. The metal has stayed in the loop; the loop has simply stopped being closed.

This is where the entire economics of sorting aluminium comes from: separated streams keep the material high in the value chain, mixed ones push it down. Which grades we settle separately is set out in the guide to aluminium grades in scrap buying.

What this means for a supplier

Three practical conclusions.

Separate where the waste arises. Offcuts from a single line are homogeneous by definition. The same material tipped into a shared container with the rest of the plant stops being homogeneous, and has to be identified from scratch — or settled at the weakest fraction.

Watch for foreign components. Steel fittings in profiles, gaskets, insulation residue and moisture in turnings all reduce the metal yield per tonne. This is not about how tidy the batch looks; it is about how much metal is actually left after the melt.

Do not guess the grade. If you are not certain what is in the batch, there is no need to settle it before delivery — commercial grading is our job, and an alloy that is not obvious is checked with a handheld spectrometer at the branch.

Post-consumer versus production aluminium

Production scrap has an advantage that no later sorting can make up for: its composition is known. The plant knows which alloy it is stamping, so the offcuts are material with a repeatable specification. It is the most valuable form of aluminium in the trade and a natural candidate for an ongoing supply relationship.

Post-consumer scrap — from dismantling, demolition, window replacement — is mixed by its nature. Here value is built through identification and separation after delivery, not through assumptions.

How much aluminium is actually circulating

Aluminium has been in use for a little under two centuries, and products made from it have long life cycles — structures and joinery serve for decades. It is estimated that a large majority of all aluminium ever produced is still in use rather than in landfill. That is good news for the loop, but it is also why demand for scrap remains high: the material comes back to the melt slowly, because it first has to finish a long service life.

The practical conclusion

Recycling aluminium always pays. A closed loop pays more — and it is not the mill that decides whether one happens, but the way the material is collected at source.

See the forms in which we accept aluminium, check how rates are set on the buying prices page, or send a material enquiry — the type and a rough quantity are enough.