Abstract:The industrial implementation of Magnetic Density Separation (MDS) in the recycling of raw materials requires more than just the science of understanding why it works ('know-why') and the technology of how that can be accomplished ('know-how'). In addition, detailed knowledge of the market for streams of end-of-life products (supply side) and the market for recycled raw materials (demand side) are paramount to optimize the practical implementation and the design of an industrial plant. Indeed, in such a plant MDS is used to separate mixed streams of recycled materials into product streams which comply with market demands on grade and purity of the product compared with virgin streams. A recently developed non-linear innovation model is used to connect four fundamental cycles which continuously interact in the process of turning MDS technology into green business. The strength of this Cyclic Innovation Model lies in connecting technical capabilities with societal market needs. Only when a good match between the two is found a new technology such as, MDS develop into an innovation. The separation of polyolefins from end-of-life product is selected as one of the first industrial-sized applications of MDS in recycling. CIM is used to identify opportunities and challenges which need to be addressed to turn the MDS technology into an innovation that builds an economically attractive business in the context of a green society.

Incineration reduces the mass of municipal solid waste (MSW) by 70% to 80%, and it reduces the volume by 90%. The resulting fractions of the incineration are bottom ash, fly ash and flue gas residue. Bottom ash is by far the largest residue fraction. About 1.1 million tons of bottom ash are produced in the Netherlands and about 20 million tons in Europe, every year. The production of bottom ash is rising because MSW is increasingly incinerated. Bottom ash is land filled in many European countries. However, the material is suitable as a building material from a civil engineering viewpoint, e.g. for embankments and foundations of roads.Bottom ash contains a considerable amount of non-ferrous and ferrous metals that should be removed for such an application. The recovery of these metals improves the engineering and environmental properties of the ash, and creates a financial benefit. Conventional dry physical methods recover only a small part of the metal value from the ash. This study gives a mass balance for the metal recovery plant of the Amsterdam incinerator (AEB). The results are based on research experiments performed in a new pilot plant for the wet physical separation of bottom ash. The recovery of ferrous and non-ferrous metals is above 70%. The metals that are found in the ash pay for a substantial part of the separation process.

The accuracy of sink-float separations in water-based media such as Magnetic Density Separation is compromised by tiny air-bubbles attached to the surface of hydrophobic materials in the feed. Separations of plastics mixtures with accuracy better than 10 kg/m 3 require a total elimination of air-bubbles by pre-wetting the surface of the feed particles with a thin film of water. Theoretical and experimental results are compared for pre-wetting processes based on condensation from the gas phase and direct liquid-solid contact for both shredded waste and virgin polymers. The tests show that the wettability of most polymers improve slightly by steaming for about 1 minute, but the best wetting results are obtained with immersion in boiling tap water. The success of wetting in boiling water can be explained by the deposition of a thin layer of calcium carbonate. Shredded plastics are easier to be wetted than virgin polymers, probably because a relatively rougher surface is caused by the shredder process. A new wetting process to eliminate air bubbles was developed on the basis of these results, which carries a minimal amount of heat and water with the feed to the MDS process liquid.