High-tech sorting systems use lasers to identify metals at lightning speed

According to Germany's Federal Environment Foundation (DBU), three medium-sized companies have made the metal recycling plant possible with technical know-how and engineering skills. East of Berlin, Alba, a waste treatment and recycling company, opened its Hoppegarten plant last Wednesday to sort aluminium from waste. Alexander Bonde, secretary general of the DBU, summed it up at the conference: "This is groundbreaking high technology. Turn waste into environmental protection. For Bond, it's all about reducing metal waste and reusing precious raw materials to make high-quality alloys. He made it clear that it was an important contribution to "more environmental and climate protection because fewer raw materials have to be extracted from the earth."

However, it will take several years of development and research before the aluminum sorting device is ready for market. This is mainly due to the collaboration of two companies, Clean-Lasersysteme GmbH and Cleansort GmbH in North Rhine-Westphalia and OSR GmbH & Co.KG in Baden-Wurttemberg. While Clean-Lasersysteme works on proper measurement techniques, Cleansort is repairing plant construction. OSR, which specialises in scrap metal trading and raw material processing, is responsible for commissioning the prototype of the corresponding plant in Rosengarten (East Wurttemberg). The German Federal Environment Foundation provided technical and financial support of more than 1 million euros for high-tech projects.

Metal recovery: Precise determination of proportion in alloys

"The technology used is characterized by the highest accuracy," said DBU Division Head Michael Schwake. Combining the two methods, the aim is to accurately determine the scrap alloys. In metallurgy, an alloy is a homogeneous metallic material consisting of several chemical elements, at least one of which is a metal. Schwake: "For everything from the automotive industry, alloy components are critical. High performance materials such as body panels or axle beams require a precise ratio of alloys. This is exactly what the Hoppegarten plant ensured when, due to expected positive sustainability and cost implications, the plant initially sorted the aluminium scrap but could essentially separate all the metal materials for later reuse.

The waste is first cleaned and inspected by a laser on the assembly line

The first step is to transport palm-sized pieces of waste, such as perforated sheets, on the assembly line. The camera examines each individual part and identifies multiple checkpoints. High-tech lasers are then used at these test sites: first clean the surface of dirt and the underlying layer, down to the base metal, and then shine a timed laser pulse directly onto the scrap component. This can be done at lightning speed in a real sense. As a result, the material evaporates and the chemical composition is determined by light emission from the metal atoms. The blowout device at the end of the process uses air pressure to separate the waste.

This laser-based sorting technique - known in technical jargon as laser-induced plasma spectroscopy (LIBS) - will make it possible in the future to precisely melt waste based on its alloy content. DBU Secretary General Bonde: "This highly sophisticated technology is an outstanding development that could revolutionise the scrap market.

Great potential of laser-based LIBS sorting technology

To DBUs experts, the potential of this sorting technique seems huge. According to her, LIBS technology can significantly increase the amount of secondary raw materials used to produce recycled materials for high-performance materials. At present, their share of German metals production is 43 per cent of copper, 69 per cent of lead, 60 per cent of aluminium and 44 per cent of crude steel. For the country's annual production of about 50 million tons of steel, about 22 million tons of secondary raw materials and another 3 million tons of alloy metal will be used.

The German Association of Metal Dealers and Recyclers (VDM) is clear about the urgency of new technologies for waste recycling. According to VDM, demand for scrap aluminium in the European Union will grow to around 9 million tonnes in the coming decades -- promising: using scrap aluminium can save 95% of energy compared to energy consumption in primary production, according to VDM. And: according to Cleansort's calculations, systems like Hoppegarten save around €6m a year in costs - and nearly 18,000 tonnes of climate-damaging carbon dioxide - running on a two-shift basis, based on German electricity prices.

Source: Laser Net