In the joint project "Shredder sand", a process was developed to recover fine-grained metals and minerals from so-called shredder sands. Shredder sands are heterogeneous residues produced when processing shredder light fractions using the VW-SiCon method. The composition of these sands varies according to the input shares to the shredder of end-of-life vehicles, white goods and mixed scrap.
Shredding is the conventional method used today to process vehicle scrap. The flows occurring during shredding are processed together with fractions containing metals from large electrical appliances and mixed scrap in order to guarantee the economical utilisation of large modern shredder units. During the subsequent processing of the shredder residues with the VW-SiCon process, shredder sands are produced which contain iron, non-ferrous metals like copper and zinc and mineral components. These contain small and minute metal particles which, up to now, have been disposed of to a large extent and thus excluded from the value added chain.
The project partners’ objective was to recover these residues via innovative separation processes instead of dumping them as has been the case so far. Existing technologies were upgraded with novel separation processes and combinations of them in order to maximise recovery of the fine-grained metals contained within them.
On average, 65 per cent of the shredder sands with particles under one millimetre in size were able to be recycled using the multi-stage process developed, which combines wet-mechanical and wet-chemical process stages. This would generate 40,000 tonnes of material per year on average in Germany alone, which could be reintroduced to the material cycle.
Four reusable fractions are formed using the new process: iron and copper concentrates, a mineral substance and a non-ferrous mixed fraction. These substances can then be used as secondary raw materials in metallurgical processes and in producing building materials.
Recycling previously dumped waste optimises the recycling chain both
economically and ecologically and contributes to conserving and