Effect of Selective Milling on the Concentration Process of Critical Raw Materials from MSW Incinerator Bottom Ash

This research introduces selective milling as a reliable and effective initial concentration process to enable efficient separation and ensure high recovery rates of valuable and critical materials (minerals and metals) from processed incinerator bottom ash (pr.IBA), a treated mineral fraction originating from the conventional municipal solid waste (MSW) incinerator bottom ash (IBA) processing steps. Four different types of pr.IBA (each sample weighing up to three tons) were selectively milled using a demonstration-scale vertical roller mill to produce three distinct products: fine, middle, and coarse fractions. Chemical analysis demonstrated that a concentration step after selective milling could be reliably achieved regardless of the variation in the sources and qualities of the input materials. Specifically, calcium-containing compounds can be enriched in the fine fraction, potentially containing Ca2SiO4, CaSO4, and CaCO3. Complementary to its particle size equivalent to the raw mix, this calcium segregation could be valuable as an alternative material in cement clinker production. Conversely, the segregation of metal-bearing substances, particularly iron and copper, was detected in the coarse fraction. Such segregation is comparable to specific ore grades and enhances the possibility of metal recovery from pr.IBA.