In 2019, 224 Mt of municipal solid waste was produced in Europe. A significant proportion of this waste is treated by incineration, producing 20 million tonnes of residual bottom ash from municipal solid waste incineration (MSWI) each year. While the coarsest fraction (> 2 mm) can be reused in the construction sector, this is not the case for the finest fraction (< 2 mm, 30% by weight), which is destined for landfill.
In this context, the Refina project brought together industrialists and academics from three countries (France, Belgium and the Czech Republic) with the aim of developing physical and chemical processes to recover the metals of interest contained in the fine fraction of bottom ash from the incineration of municipal solid waste. The objective of this project was twofold: to recover the elements of interest and to "clean" the residual materials before using them as substitutes for cement and sand in concrete formulations intended for applications in the construction sector.
The goal of Mathilde Perrin's thesis was to study the feasibility of selectively recovering copper and zinc, whose concentrations in the fine fraction of bottom ash are comparable to those in low-grade ores. A four-step process was designed, comprising rinsing, leaching, precipitation and electrodeposition. A selective leaching stage using a solution of ammonia and ammonium chloride was carried out to avoid co-leaching of iron. After the leaching stage, zinc precipitation was carried out by adding aluminium nitrate, followed by copper electrodeposition from an ammoniacal medium. Up to 70% of the Cu and Zn could be recovered with minimal changes to the composition of the leachate, allowing it to be reused. The process developed makes it possible to recover metallic copper and zinc in the form of spinel from waste that was initially destined for landfill.
Perrin M., Svecova L., Deseure J., Closed-loop process for Zn and Cu selective recovery from MSWI bottom ash fine fraction, Minerals Engineering 203(2023)108353, https://doi.org/10.1016/j.mineng.2023.108353
