Recycled aluminium vs pure aluminium

Aluminium is the most abundant metal on Earth. The physical and mechanical properties of aluminium make it the ideal choice for parts that can be used in almost any industry. Aluminium is corrosion-resistant, durable and has a high strength-to-weight ratio.

Benefits of choosing aluminium for your part

When considering the type of metal for an application, many companies put aluminium at the top of their list. With its unique mechanical and physical properties, aluminium offers design engineers significant advantages. The metal creates lighter parts with more surface finishing options than other die casting alloys. It can also withstand the highest operating temperatures of all die casting alloys, making it a great choice for products that require heat dissipation, such as computers and handheld devices. Moreover, cast aluminium is versatile, corrosion-resistant and retains high dimensional stability with thin walls, allowing it to be used in almost any industry.

With all the benefits aluminium offers, it may come as a surprise that most aluminium is actually mixed with other materials such as magnesium, iron and copper. This is because the use of pure aluminium, or primary aluminium, in casting is quite costly due to the high amount of energy used during extraction. Recycled aluminium, or secondary aluminium, is much more cost-effective and readily available—not to mention beneficial for the Earth.

How do you extract pure aluminium?

150 years ago, aluminium was more expensive than gold—not because of how rare it was, but because of how expensive it was, and still is, to extract. Production of primary aluminium is quite demanding and costly.

In its purest state, aluminium is extracted from a clay ore called bauxite. The bauxite ore is purified to yield a fine white powder, aluminium oxide. Aluminium ions are separated from the oxide through electrolysis—a process in which aluminium sinks to the bottom of a melt tank in liquid form and is withdrawn and solidified to become the metal we recognise as aluminium.

Extracting primary aluminium is not only energy-intensive, resulting in high costs due to the amount of electricity used, but also environmentally detrimental. Large amounts of CO2 are released into the atmosphere during the extraction process, making recycled aluminium the perfect alternative for a more energy-efficient source of aluminium.

Recycled aluminium

Aluminium is 100% recyclable. And 75% of all the aluminium ever produced is still in use today. Since aluminium maintains all of its physical and mechanical properties, it makes the perfect, greener replacement for primary aluminium.

Secondary aluminium begins by being extracted from various waste streams. Scrap is separated by chemical composition—with purer forms of recycled aluminium maintaining the highest value and aluminium containing mixtures of other alloys and materials having the lowest. Since aluminium is non-magnetic, contaminants are removed from the scrap using magnets to remove debris. The remaining aluminium is shredded into small pieces, stripped of existing surface finishes and melted down to purify the molten metal. The final product is an aluminium alloy with pure aluminium properties.

Closed-loop recycling

Industrial scrap, or discarded metal from manufacturers and other foundries, is a key source of material for suppliers to recycle. At Dynacast, we send all scrap produced as a by-product of our operations for recycling and use in future projects. The closed-loop cycle prevents waste from going to landfill.

Consumer products make up the remaining scrap that is recycled. Items such as aluminium window frames are sorted, shredded, cleaned and melted before all by-products are removed. At this point, other alloys can be added to the aluminium, creating an almost exact recreation of primary aluminium.

Savings from recycled aluminium

The amount of energy used to produce aluminium is the ultimate differentiator when it comes to cost. Primary aluminium extraction uses a great deal of energy, consisting mainly of electricity, natural gas and liquefied petroleum gas consumption. The aerospace industry is most commonly known for using primary aluminium due to strict regulations and quality measures. Using secondary aluminium is a more energy-efficient choice than extracting pure aluminium, since casting secondary aluminium can produce a large amount of usable material with less effort. To put it in perspective, recycled aluminium uses approximately 90% less energy than mining for pure aluminium.

Most of the energy consumption in aluminium die casting is used to heat and remelt the metal during fabrication. For this reason, Dynacast is able to save more time, energy and money by remelting in-house. Since most products can be cast from secondary aluminium while still maintaining similar properties and material characteristics, recycled aluminium can be a sustainable solution for your next design.