Experimental recovery of metals and glass for recycling and minerals as aggregate for concrete from waste incineration bottom ash: a case study from Austria

Abstract

A circular economy of metals, glass, and minerals in grate and fluidized-bed waste incineration bottom ashes requires enhanced treatment after standard treatment. This study presents an experiment for such an enhanced treatment. Samples of standardly treated bottom ashes were randomly collected and enhanced treated by wet sieving and drying, metal and glass separation. Metal and glass concentrates were analyzed for their quality for recycling, and production tests were made with the remaining minerals to evaluate their use as aggregate in standard concrete. Experiment results were analyzed by material flow analysis, and finally used to design and calculate metal, glass, and minerals recovery in an industrial-scale scenario. In the experiment, substantial additional quantities of metal concentrates with high metal contents were found and recovered from grate incineration bottom ash, but not from fluidized-bed incineration bottom ash. The amount of glass concentrates and the glass content in these were higher for fluidized-bed incineration bottom ashes. Remaining minerals from both ash types were suitable to be used as manufactured aggregates in concrete. Future studies should focus on the environmental and economic impacts of applying enhanced bottom ash treatment as performed in this study on an industrial scale.