Laser gets it sorted - A revolutionary sorting machine

As technologies develop new products often unexpectedly migrate and cross over into other fields. Belgium’s Visys NV Cleantech Sorting realized their compact laser food-sorting systems could be a valuable tool in the recycling industry by Pieter Willems The increasing global interest in recycling, along with international legislation on product quality and operating procedures, is paving the way to new product developments. Technologies are being combined, blended and often become applicable in completely different fields. The food industry, where the product specifications are extremely stringent, is one such area where new developments are crossing the boundaries. It can take time for food industry technology to infiltrate into the recycling business, due to the differences in product standards and operating environments. However, in the case of Visys NV Cleantech Sorting, a Belgium-based company specializing in the design and production of digital laser sorting machines, this was time well spent. The company discovered there was a need for many of the features of its food sorters in recycling equipment, and when it developed a machine which utilized these features, it started out on the road to success. Besides the sorting efficiency, many other parameters were a challenge for the team. Features like sorting stability, flexibility and ease of use needed to be included in the design, and have now been combined into a compact, small footprint device. Laser light source Conventional light sources, like light bulbs, tubes or halogen spots typically need a relatively long warming up time to bring the light source to a stable level. Ageing on the other hand creates a downfall of light output. On top of this, it is necessary to have light sources located relatively close to the product stream to provide sufficient illumination of the product being sorted. In a dusty and dirty recycling environment, these light sources become grubby, resulting in less light on the product, and hence a shift in the sorting results. Regular cleaning and re-calibration is therefore a must. Visys NV Cleantech Sorting’s digital laser sorting machine Click here to enlarge image A laser on the other hand, behaves as a virtual digital device, so is either on or off (0% or 100%). On top of this, Visys folds the laser light source away in optical boxes which are under constant pressure to keep the optics clean. Although simple, this is probably one of the most interesting features of a laser it reflects directly on the sorting output and once settings are made there is no need for calibration and the product quality will remain constant. No more belts Existing sorting systems often make use of long black belts in order to speed up the product and stabilize it before it enters the illumination/inspection zone. Belts are subject to damage, and round objects risk deviating from their path between inspection and subsequent ejection. Visys uses a short feeding vibrator followed by a slide down. The 0.5 metre slide accelerates the product and brings it to the laser detection line. Just 5 cm below this detection, air nozzles eject the wanted or unwanted material. There is no time for an object to change path and influence the sorting process. This mechanical set-up assures only a small amount of floor space is needed for the device and the combination of the in-feed vibrating table and machine offers a ready to use solution. Flexibility on the same platform In general there are three parameters which are taken into account to make a decision in the sorting process colour, structure and shape. All of these can be combined ‘uncompromised’. Whereas other systems on the market are mainly used for one application, the Visys digital sorters can switch use in just ten seconds. Implementing a special module, like the ‘PCB (printed circuit board) Locator’, which is embedded in the system, can be done at any time. A selection of multiple laser wavelengths and the choice for single-sided inspection or double-sided inspection improves flexibility. The normal set-up uses a two-stream system: creating an ‘accept’ and a ‘reject’ stream, but it is also possible to split the machine up into two parts. One lane can be used for the main stream, while the second lane can be applied for re-passing the accept or reject stream. In this way, a three-stream flow is obtained. Multiple applications The application range is virtually unlimited. Some examples include: WEEE, glass, wood, plastics, car scrap, metals and ore. Although not obligatory, the devices perform best on products that have been pre-cleaned by traditional methods, like an over-belt magnet, eddy current or aspiration system. In WEEE sorting, one can choose to sort the incoming shredded product, or sort after the eddy current has been applied. PCBs can be separated from aluminium and plastics by means of the PCB Locator where there is a possibility to remove only PCBs, or in combination with copper. On the other hand, if one wants to focus on plastics, this can be done as well. Glass fractions can be cleaned from any remaining paper, plastics, metal etc., while in some other applications glass can be removed from the main stream. In case of cathode ray tube (CRT) glass, remaining impurities, like metals and plastics can be removed. On a sample of CRT glass that hasn’t been washed, funnel and front glass can be separated. Mixed waste, including printed circuit boards (PCBs), are easy to sort by laser Click here to enlarge image In the process of sorting wood all foreign bodies like foils, plastics, metal and stones are separated from the wood, and high efficiencies are reached on MDF. Whole scrap cars are shredded but different fractions need to be separated in order to recover precious materials. Using Visys technology the process can be performed on the same platform. This application flexibility is a unique set-up in the sorting industry. Where existing devices are limited to a specific application, the Visys sorters can multi-task, and are able to change application in just a matter of seconds. Easy to set and run Built-in scope functions allow the user to assess the reflections of the laser light source on different materials. The operator can evaluate the differences and set the machine quickly. Conclusion With EU regulations on waste to become more stringent, the call for new technologies is stronger. Landfill prices are rising, and the fact that waste streams do contain precious elements makes it attractive and favourable to invest in new and innovative technologies. Existing technologies will continue to be fine-tuned. In the field of magnets, new and better solutions will be found, and future improvements will be made to optical sorters and mechanical separators. Flexibility will be inevitable, as there will be a need to keep on reducing rest fractions, since these will be due for landfill. In order to tackle the many challenges in the recycling facility, and to create multiple fractions, the need for flexible, highly-efficient technology is clearly needed. Visys NV Cleantech Sorting offers a novel solution. Multiple applications can be run on the same device, and all future developments will be designed to be run on the same platform leaving the customer with a very powerful tool. Mechanically, one can avoid the use of transport belts, so the machine’s size is compact. Visys NV Cleantech Sorting’s future developments will result in more specific modules being designed for use on the existing platform. In this way, the customer benefits from the current set-up, with the possibility of upgrades in the future. Pieter Willems is sales director of Visys NV Sorting Systemse-mail: pieter.willems@visysglobal.com