Page 36 - Hub-4 Magazine Issue 70

Recycling-MRF’s/Shredders/Balers
So why are we producing any new aluminium at all?
Hoffmann: These days to be able to produce certain quality alloys, we still need primary aluminium, the manufacturing process for which is highly energy intensive. Maintaining high quality levels for recycled aluminium requires intelligent cycles using highly efficient recycling technologies, such as sensor- based sorting technology. This can then compensate for the downgrading of material qualities experienced in the recycling cycle, which also enables secondary aluminium to be efficiently used in the production of what are known as aluminium wrought alloys.
What is the importance of aluminium alloys?
Hoffmann: There are hundreds of different alloys and, depending on the requirements of the application in question, they provide various mechanical properties, such as strength or hardness. Developments in this field are highly dynamic. In the automotive sector, for example, it has long been standard to produce body parts from aluminium. And now, supporting parts, like suspensions are being manufactured out of recently developed aluminium alloys or even aluminium compounds. Of course, the engine itself is already mainly made from cast aluminium. Several automotive manufacturers have already honed in on aluminium as a material. Aluminium’s lower weight helps them comply with ever tighter CO2 emission requirements; the density of aluminium is 2.7 times less that of steel.
Aluminium will also be a key material for electric vehicles. The more steel is replaced with aluminium, the greater the range of an electric vehicle. Its potential for the future is huge too.
Alongside these large potential savings in CO2 emissions driven by lightweight design in the automotive sector, this potential will also be boosted by the efficient and specific use of recycled aluminium to reduce greenhouse gases.
Using recycled aluminium consumes around 95% less energy than primary aluminium. But precise sorting technology is essential for ensuring high-quality recycled goods.
STEINERT XSS T EVO 5.0 sorts heavy metals from light metals like aluminium
How do you ensure as high a grade of aluminium as possible from recycling?
Hoffmann: It goes without saying that this depends a great deal on the input material. The quality needed of course also depends on its intended use. Course impurities, like plastics or
wood, can be removed with relatively simple technology, involving eddy current separators.
Sensors can sort to a much finer degree. X-ray transmission technology is basically the same as that used in the medical profession where the absorption of x-ray radiation makes different material densities visible. When sorting metal, this means that pieces of metal on a conveyor belt can be radiated and classified into materials and purity levels to a high degree of accuracy.
The huge advances made in detection, software and the processing of signals deliver a combination of very accurate sorting and high speed. Compressed air is then used to separate good parts out from not so good ones.
What happens then with the sorted material?
Hoffmann: Smelting plants buy the metal to process it further. But there is also an option of further sorting the aluminium into alloys. The more precisely this is done, the more specifically the material can be used. We then inch ever closer to the goal of a closed cycle, in other words, a circular economy.
What technological advances have been made recently at STEINERT?
Hoffmann: Not long ago, we updated our system with x-ray transmission technology. We call the system XSS, which stands for x-ray and sensor sorting, the latest innovation bears the add-on EVO. This embodies developments made over the last five years. For example, we are now able to detect various material characteristics much more precisely than was previously the case. This is mainly thanks to enhanced signal processing. Nowadays, the systems are able to better separate out certain alloys. What’s more, we are also now able to separate free magnesium, a metal that is frequently found in aluminium scrap and if not detected causes considerable extra work in aluminium smelting works. This is challenging because, like aluminium, magnesium is a light metal and its absorption coefficients for x-ray radiation are therefore very similar.
Have you made any other breakthroughs?
Hoffmann: Yes, we have made the components in our systems even more resistant. The x-ray source, a key and costly component, for example, now comes with a four-year warranty, which is unique in the sector.
What is happening on the markets right now?
| p36 |
www.hub-4.com Sept-Oct 21 - Issue 70