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The recycling of Waste Electrical and Electronic Equipment (WEEE) is gaining greater importance at a global level. Historically, the EU has driven developments in this field, establishing EU-wide legal regulations in 2003 in the form of the WEEE Directive (RL 2002/96/EC). These regulations govern the treatment of this complex waste stream and demand that disused electrical equipment – or E-scrap – must be separated and recycled. Since the introduction of the EU legislation, more and more countries have followed suit, introducing regulations that aim to ensure the safe recovery and recycling of E-scrap.
E-scrap has a complex composition and encompasses anything from computers, office electronic equipment and gadgets, to mobile phones, television sets and refrigerators. E-scrap includes used electronics which are destined for reuse, resale, salvage, recycling, or disposal. The typical composition of this waste stream of WEEE
categories 1-9, without large appliances/cooling devices, screens and TVs, is as follows: ferrous metals (40%), non-ferrous metals including PCBs (25%), plastics (30%), glass, wood and other materials (10%). *
Not only does this waste stream contain a number of hazardous components, but it also contains a significant amount of valuable and scarce raw materials, such as stainless steel, aluminium, gold, silver, copper, brass, indium and platinum. In fact, E-scrap contains up to one hundred times more precious metals than the same amount of the primary resource, ore.
The key objective for WEEE processors is to remove all of the pollutants, while also recovering the profitable components at high purity levels, in the most cost effective manner, so let’s look at how this can be achieved.
How the technology worksThe core components of conventional processing of E-scrap are shredders, air separators, magnet, manual controls, sieves, and non-ferrous metal separators. In order to achieve the greatest yield and highest purity levels, sensor-based sorting systems are often used downstream of the ferrous and non-ferrous metal separators in recycling plants.
At this stage, the best results are achieved if the material is screened into the following particle sizes: 0 – 8mm, 8 – 25mm and 25 – 50mm. Each of these fraction sizes can then be further sorted using a combination of sorting steps and processing procedures. Here is a typical example of how TITECH’s sensor-based sorting technology can operate:
A TITECH finder initially separates all metals from non-metals before sorting the metal stream further into PCBs, non-ferrous metal concentrates, cables, copper, brass, stainless steel and precious metals. The TITECH finder has been designed to separate high purity metal fractions from even the most difficult fractions in terms of composition.
The non-metal fraction, including plastics, then goes onto the TITECH autosort, where the material can be further sorted by any colour and any polymer required. The TITECH autosort combines near infra-red (NIR) and visual (VIS) sensors that are able to simultaneously sort material by material type and colour. For plastic recovery, the focus is on the main polymers ABS1, ABS-PC1,5, PS2, PE3, PP4 and PC5. Whereas conventional technology loses these resources, TITECH’s systems are able to identify and separate each individual polymer.
A combination of the TITECH finder and TITECH combisense can then be used to further sort the material depending on the plant’s requirements. The TITECH combisense is designed to identify colours, shapes and metals from bulk solids. The metal sensor is combined with a colour camera and the high spatia l resolution in conjunction with precise colour measurement makes it possible to sort and separate complex material streams such as PCBs, brass and copper.
Depending on the system design and the material value, TITECH machines run in so-called online or batch operation. Each of the above steps can then be applied across all three grain sizes of fractions: 0 - 8mm, 8 – 25mm and 25 – 50mm.
One of the key benefits of sorting technology is its flexibility: detection techniques like metal sensors, colour line cameras, near infrared (NIR), X-ray transmission technology and visual spectrometers (VIS) can be applied in a flexible way and combined with each other. This means that solutions can be tailored to the individual requirements of each processing plant
By setting up a trial on a processor’s shredded material, TITECH is able to identify whether one particular grain size range is very high in value. If this is the case, then the sorting solutions can be concentrated on highest value size range, resulting in the best payback on investment for the processor. Typically, on a WEEE project, the return on investment is less than 12 months.
By designing the optimum combination and co-ordination of the machines in the system, it is possible to achieve yield results of over 98% and product purities of up to 95% -
levels that would never be possible using conventional technology to process WEEE waste.