Maximum sorting efficiency and increased scrap aluminum quality 

Aluminum is a light metal with a bright future, and its production is tending to increase, as the material largely replaces steel in many applications thanks to its strength and low weight. A clear example is the automotive sector and even more so in electric cars, where weight reduction is crucial," says Brian Gist, Sales Director Metals at TOMRA Sorting Recycling.

Therefore, when using recycled material, quality control is essential. This process starts with the scrap aluminum recyclers, as they supply raw materials to the aluminum producers. However, the latter must verify that the materials they have purchased meet the respective quality requirements. Both recyclers and producers must, therefore, be involved in the improvements in the classification of materials.

In this way, aluminum producers control the quality level before the material enters the furnace and avoid the loss of castings due to heavy metal peaks exceeding the maximum allowable content of these elements," Brian Gist points out. "TOMRA’s technology becomes a second control barrier after the materials have been processed by the recyclers".

This secondary aluminum production using scrap material recycling has a fundamental positive role in the recycling economy. It increases recovery rates and delivers a high quality end product with a lower carbon footprint, since it requires lower energy and raw material costs compared to the primary aluminum smelting process. The latter uses bauxite ore as a raw material and requires high energy consumption and complicated physico-chemical processes.

In the words of Brian Gist: "We believe the trend today is for aluminum producers to continue to develop their processes for separating raw materials. It has even partially replaced the work of the recyclers in terms of material differentiation, creating new qualities that are always adapted to their needs".

Not using a technology such as the XRT from TOMRA involves several risks if the material does not meet the required specifications in terms of composition and grain size. The final product may not achieve the desired properties. Furthermore and in order to compensate for this quality deviation, other types of materials have to be added during the refining process.

For example, a process of dilution and/or addition of various additives may be required, which results in very high costs per ton of the final product produced. In short, significant economic losses, as well as greater instability and lack of control at the kiln entrance are to be expected.

What XRT technology means for remelters and refiners

Today, there are a variety of systems used by the aluminum industry or by the supplying scrap companies to process the material: XRT technology, dense media separation, densimetric tables and even manual separation. This range of possibilities leads to the creation of materials of very different origins and with very different qualities. In fact, many processors of scrap have their own quality laboratories with melting furnaces, and results are often sent to the scrap customers to prove both traceability and compliance with the required quality standards. In this sense, TOMRA's XRT technology is a fundamental tool to achieve consistent product quality and to generate new fractions with higher added value, allowing the recyclers to sell their products at a much higher price/tonne.