Metal recycling is a growing business area with potential for extensive economic and environmental benefits. A significant part of the metallic waste that is fragmented in Sweden is exported and refined via manual sorting. Automating the sorting process would make it possible to increase the amount of recycling, reduce the environmental impact of the already existing operation and make it possible for the entire recycling process to be accommodated within Swedish industry.
In conjunction with Acreo (another RISE institute), Stena Recycling and Outokumpu, Swerea KIMAB is developing a laser-based metering system with the objective of identifying and determining the chemical content of a material in less than one hundredth of a second, and doing this at a distance of up to several metres.
The LIBS system uses very short laser pulses to locally heat the sample and detect its spectral fingerprints, i.e. the light that the sample emits. This light is unique and characteristic for each individual material and discloses the composition of the sample. A compact prototype has been designed at Acreo, and element analyses and classification of authentic pieces of scrap from Stena Recycling have been performed in a laboratory environment using an analysis programme developed at Swerea KIMAB. Field experiments for sorting scrap were performed in 2011 at industrial plants.
The number of future industrial applications for a compact LIBS technique is very high, according to Simon Lille at Outokumpu Stainless:
"We see great potential for using the technique. In the raw materials field today, we have to have physical contact with the raw material to check for mistakes. In the future we will be able to scan an entire consignment to find non-relevant materials and contaminants and at the same time get an understanding of the composition. A rapid and certain analysis of material that has been delivered means that we can shorten our lead times considerably."