Recycling and Utilisation of Secondary Aluminium Products
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Efficient utilisation of secondary aluminium products is increasingly important as the energyconsumption and CO2 emissions are greatly reduced by recycling compared to primaryproduction. The aim of this study was to compare the recyclability of used beverage cansto incinerator metal, and investigate the efficiency of an environmentally friendly salt flux.In addition, an alternative to traditional recycling was executed to potentially increase theutilisation of dross. Used beverage can scrap and incinerator metalwere melted under two different salt fluxes intwo different induction furnaces one 20 cl. crucible and one 500 cl. crucible. For the smallscaleexperiments the coalescence was measured by sieving the resulting metal pieces. Inthe larger scale experiments, the yield was measured through a mass balance and the metalwas analysed through inductively coupled plasma mass spectrometry and electron probeanalyser. Furthermore, clean aluminium and dross were charged into a pre-prepared molten CaOSiO2slag at 1600±C for the purpose of aluminothermic reduction of SiO2. The resulting metaland slag phases were chemically analysed by inductively coupled plasma mass spectrometryand electron probe analyser, and compared to results obtained by thermodynamic modelling. The results indicate that the incinerator metal is highly recyclable, as it is easily coalescedand produce yields in the same region as used beverage cans. However, lead contaminationsare present in the raw material leading to relatively high lead contents in the resulting metal,which could be detrimental for the finished product. As for the salts, the operating temperature seems to be of importance for their performance.Temperatures close to the salts solidification temperature result in low yield, which is alsoconfirmed by theory. In the small-scale experiments, the recycled salt seemed to performvery well, while the two salts performapproximately equal in the larger scale experiments. Moreover, from the preliminary experiments on aluminothermic reduction, dross seems likea suitable reducing material for aluminothermic reduction, as the chemical composition isvery close to that obtained for clean aluminium. However, the obtained chemical compositionsdeviate from the theoretical composition, most likely due to the solidification procedure.