Tomra’s XRT sorting technology facilitates the classification process and optimizes the efficiency of sorting secondary aluminium raw material.
The quality control of aluminium scrap used as secondary raw material in metal production is becoming increasingly stringent. First class material is not always guaranteed for manufacturers which are dependent on buying recycled aluminium materials. Tomra’s X-Ray Transmission (XRT) sorting technology with its X-Tract and X-Tract X6 Fines units is highly recommended for efficiently separating aluminium and aluminium alloys from heavy metals, which delivers consistent quality for the resulting raw materials and products.
“Aluminium 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 recyclers, as they supply raw materials to the aluminium 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.
XRT sorting technology provides benefits for scrap processors and recyclers
Tomra’s XRT sorting technology facilitates the classification process and optimizes the efficiency of sorting secondary aluminium raw material. This applies to those who use aluminium scrap consisting of several alloys and heavy metals, including copper, zink, iron, magnesium, silicon, etc.
“Prior to the melting process of secondary aluminium, our XRT technology separates the heavy metals from aluminium alloys containing more than 2% heavy metals before entering the furnace. Each aluminium alloy contains a certain percentage of other metals, which must be constantly controlled to ensure that the chemical composition of the product meets the required specifications. In this way, aluminium 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,” Gist points out. “Tomra’s technology becomes a second control barrier after the materials have been processed by the recyclers.”
This secondary aluminium 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 aluminium smelting process. The latter uses bauxite ore as a raw material and requires high energy consumption and complicated physico-chemical processes.
Tomra’s XRT technology even compounds the advantages when used by refiners and remelters. Using the sorting technology in the process can lead to a reduction in the purchase costs of the raw material (scrap), firstly because the materials do not have to have an excessively strict composition and secondly because less is processed. Thus, scrap can be bought at a lower price with a lower quality and subsequently cleaned by X-Tract technology. “Secondary smelters, who are particularly interested in separating scrap to pure fractions, now have the possibility of buying raw materials at a lower price and sort it with Tomra’s XRT technology to achieve the desired quality level. A very favourable option,” clarifies Gist.
Apart from cleaning scrap, they can moreover produce new fractions, for example by separating the crankcase from the profile.
X-Tract and X-Tract X6 Fines
Tomra has two models that incorporate XRT technology: the X-Tract and the X-Tract X6 Fines. Firstly, the X-Tract enables sorting by recovering ready-to-melt aluminium fractions with a purity of 98-99%. The XRT technology also enables substances to be separated according to their atomic density, regardless of their colour and surface impurities. Tomra’s X-Tract X6 Fines identifies and classifies grain sizes that are almost half the size of those that could previously be processed (between 5 and 40 mm). In addition, the heavy metals separated with this device can be further separated by the Combisense Belt system by colour, brightness and shape.
The operating costs of Tomra’s sensor-based dry sorting systems are significantly lower compared to a system with dense media that uses water and additives. Additionally, dry sorting makes the necessity for water treatment obsolete.