Wood is a building material with outstanding cascading potential. Solid wood represents the highest value product in the cascade which at the end of its service life can be converted into newproducts extending the sequestration of carbon prior to the combustion of wood for energy production. The key to maximize the sequestration of carbon is to extend the service life of wood at each level of the cascade. Recycling of timber and wooden packaging as feedstock to produce wood-based panels or energy recovery is a current common practice. The concept of reclaiming full-sized timber as raw material for structural timber elements, has not been developed to an industrially viable solution so far.
One bottleneck in a potential production process is the detection of harmful or hazardous contaminations in the timber and sorting of the timber into different categories according to the degree of contamination. Contaminants of concern range from metal fasteners and concrete residues that can damage downstream machinery like saws, finger-jointing mills, and planers, to CCA containing wood preservatives and lead (Pb)-containing paints banned due to their toxicity. Near infrared spectroscopy (NIR), X-ray fluorescence and laser-induced breakdown are technologies that have been applied to detect contaminations in wood from construction and demolition (CD)-waste. However, industrial in-line application of the technologies and automated separation of timber pieces bigger than 50 mm has not been realized so far. The aim of the study covered in this paper is to evaluate the suitability of a state-of-the art industrial detection and separation line to sort pieces of timber. The study aims to explore potential and boundaries of commercial in-line waste wood sorting equipment for sorting and separation of reclaimed timber. The trial was conducted in the recycling test center of TOMRA Recycling in Mühlheim-Kärlich.
Keywords: reclaimed timber, CCA, contamination, detection, sorting
Authors
Karl-Christian Mahnert
Norwegian Institute of Wood Technology
Roja Modaresi
Norwegian Institute of Wood Technology
Ivar Ragnhildstveit
OMTRE
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