ALUMINUM SCRAP SORTING

How to sort aluminum scrap

Sorting aluminum scrap is not just good for the planet – it’s good for business. From the collection of used materials to melting and remanufacturing, the process is designed to preserve the value of this versatile metal.

Input material preparation and ZORBA fraction

Aluminum scrap, including profiles, used beverage cans (UBCs), and shredded fractions from end-of-life vehicles and household appliances, but also production or new scrap, enters the recycling stream as part of mixed scrap – or after precleaning referred to as ZORBA.

Pre-treatment and ZORBA processing

This fraction contains aluminum and other non-ferrous metals and must be cleaned and pre-shredded. After this, the scrap sorting process begins.

Separating out iron

Magnetic separation of ferrous metals

Firstly, magnets are often used to separate free iron pieces and compounds out of the material flow. This is essential to prevent contamination in subsequent processing steps and to recover valuable ferrous metals.

STEINERT magnetic solutions

Magnets such as STEINERT BR magnetic head pulleys and STEINERT UME overhead suspension magnets are often used for this purpose. They ensure efficient and continuous removal of iron components from the scrap stream.

Non-ferrous separation

Recovering non-ferrous metals and aluminum

After removing ferrous using magnetic separation, the next step is the extraction of non-ferrous metals. For this process step our eddy-current separator STEINERT EddyC has become a global standard. The so called non-ferrous metal separator recovers nf-metals while cleaning the metal fraction from undesired materials like plastics, wood or glass. The generated ZORBA predominantely consists of aluminum, but also contains heavy metals like copper, brass or zinc. 

Sensor-based sorting in an aluminum recycling process

ZORBA fraction purification

This mixture of light and heavy metals (separated by grain size) is now separated using X-ray technology (STEINERT XSS T EVO 5.0) into aluminum and the mixed fraction of copper, brass, zinc, etc. This achieves a maximum yield and purity of aluminum and the material can be marketed in a defined quality.

Application for profiles and light aluminum scrap

For fractions of profiles and light aluminum scrap, wet mechanical separation of free heavy metals and high-alloy aluminum components (such as cast parts) is often not economically viable.

Dry sorting by atomic density

In such cases, dry mechanical sorting by atomic density provides a reliable alternative or flexible addition to sink/float separation to meet changing quality requirements. The above-mentioned grain-size-separated fractions are then processed using the STEINERT XSS T EVO 5.0.

High-purity aluminum output

This system effectively separates aluminum scrap from a mixed fraction of copper, brass, zinc, and other free heavy metal pieces. It enables the separation of high-alloy aluminum and free heavy metals, achieving aluminum scrap purities of more than 99.8%.

Cast / wrought separation

The separation of cast and wrought aluminum using XRT-technology is essential to preserve material quality and value. Cast aluminum typically contains high levels of alloying elements such as silicon—often exceeding 15 %—while wrought alloys have significantly lower silicon content, usually between 0.3 % and 5 %. When both types are melted together, the silicon-rich cast aluminum contaminates the wrought fraction, making it unsuitable for high-quality applications. Since silicon cannot be efficiently removed in metallurgical processes, dilution with primary aluminum remains the only option—an expensive and resource-intensive approach.

Maintaining a clean and clearly defined wrought fraction is therefore crucial. It not only prevents downgrading of valuable material but also forms the foundation for subsequent alloy-specific separation steps, ensuring the highest possible purity and quality in aluminum recycling processes.

Modular process for specific aluminum grades

The two-step approach with eddy current separation and sorting by atomic density not only maximizes aluminum yield and purity but also enables recyclers to market the material in well-defined qualities – such as Al 224, Taint Tabor (mainly clean sheet goods), or high-value premium grades. Our systems are modular and scalable – tailored to your input streams and desired product purity.

Enriching Free Magnesium in NF Metal Streams

In mixed non-ferrous metal streams, aluminum is often accompanied by small amounts of the light metal magnesium. Since magnesium has an even lower density than aluminum, advanced sorting systems using X-ray transmission (XRT) can identify and separate it as a distinct material class. 

By analyzing material density and atomic composition, XRT technology enables the targeted enrichment or removal of free magnesium, depending on process requirements. This precise detection ensures that valuable light metals are recovered efficiently, while minimizing contamination within aluminum fractions and enhancing the overall purity and value of the recycled output.