TJ: The TOMRA sorting technologies have been used for ELV recycling for two decades. This started with the recovery of metals from residue streams, to divert residual metals which were ‘missed’ by traditional non-sensor based equipment (such as magnets and eddy current separators) from landfill. In the developed markets, the majority of metals are therefore being recovered for a long time. In less developed markets, this is still however an area where recyclers can improve.
Typical traditional products of metal scrap, such as Zorba (mixed non-ferrous metals) and Zurik (mixed metals after FINDER induction sorters), were sold to Asia where they were sorted manually. Since the mid-late 2000’s, the focus of recyclers changed to further sort these mixed fractions by using sensor technologies. This creates added value by producing mono-fractions with more overall value than the mix, but it also provides more options to sell metal scrap products directly to (local) processors (such as remelters), instead of using traders in between.
After a difficult period for the recyclers in the first half of the 2010’s, this trend has again picked up in recent years. The existing sorting technologies are improving, (increasing in speed, resolution, etc.), multiple technologies can be combined, and new technologies are being developed. This is allowing recyclers to add sorting steps and further increase purities. The real driver is that quality is king – recyclers producing mixed or contaminated products will have increasingly more difficulties selling.
Can you briefly tell us the “heart” of a TOMRA machine, that is to say how the selection of ferrous and non ferrous metals – and fluff – works? (may be some words on Combisense, Finder, X-Tract)
TJ: For the recycling of ELV’s, there are four sorting technologies that are predominantly used, either separately or combined. At TOMRA, these are included in the following sorting units:
FINDER: Sorting unit using an electromagnetic (EM) or induction sensor. This sensor provides information on metal signal, as well as shape, size and to some extent metal type in the latest generations. The FINDER is mainly used for recovering metals from residue, and sorting them into stainless steel and copper wire concentrates.
- FINDERPOLY: EM sensor combined with near-infra red (NIR) or LOD (laser) technology. NIR allows the recognition of plastics and other non-metals. Typical applications are the sorting of plastics and/or wood from residue, but also the upgrade of stainless steel and wire concentrates by LOD.
- X-TRACT XRT: Uses x-ray transmission (XRT) technology to sort material based on a difference in density. Mainly used for sorting of Zorba (product of an Eddy Current: aluminum, copper, brass, zinc and others) into aluminum and mixed heavy metals.
COMBISENSE: Uses an RGB color camera combined with an EM sensor. This unit is mainly used for sorting of mixed non-ferrous metals by color; in ELV recycling, typically the mixed heavies are sorted into copper (red), brass (yellow), printed circuit boards (green) and zinc/alu (grey).
At the end of the selection cycle, what are the secondary raw materials recovered? And what does the rest of the material consist of (and where does it go to)?
TJ: Every recycling plant is different, and it heavily depends on the location, market conditions, regulations etc. For a typical state-of-the-art sorting plant in a developed EU country, the material fractions recovered are:
- Zinc and other grey heavy metals
- Stainless steel
- Copper wires
Residual fractions can include:
- shredder light fraction (SLF), which is typically removed by windsifting at the shredder. This contains dust, foam, fluff, textiles etc, and is typically treated in specialized plants to recover residual valuables.
- Residual plastics and rubbers. These can be further sorted at specialized plants, but are also used in incineration plants.
Can TOMRA technology help improve the quality of the car fluff? How?
TJ: Yes, but it depends on how ‚car fluff‘ is defined. Normally car fluff means the SLF (see above), which is the most difficult material to sort efficiently by sensor equipment. Several mechanical treatment steps are needed to concentrate materials, then FINDER can be used to recover metals, NIR can be used to sort wood and/or plastics and a COMBISENSE chute can be used to sort fines metal fractions. In many cases, the low amount of valuable material and efforts to recover it makes this challenging, both economically and from a sorting perspective. However with recycling targets as well as costs of alternatives continuing to increase, the recovery and sorting of valuables out of fluff will also become more and more important.
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