Increased resource efficiency through selective fragmentation of bottom ash

Important results from the project

The project´s partial goal of gaining acceptance for the method and results from selective fragmentation of Swedish bottom ash has been met, while the partial goal of a business model where the mineral component becomes a new fraction that can be recycled requires more research. A sustainable business model for the Swedish market requires a solution for how the sorting rest is recycled and that the mechanical properties of the mineral fraction are the same as those of virgin products. It must also be proven that the fractions are not harmful to people´s health and the environment.

Expected long term effects

Sorting of slag from Swedish bottom ash into several fractions was successfully done in Switzerland, as well as chemical testing of these fractions in Sweden. The method demonstrated an increased metal recovery of 20 to 30%, generating increased revenue and environmental benefits. In Switzerland they are using mineral fraction in concrete production, iron oxide as an additive in cement production. Recycling has also been certified to obtain CO2- credits. For a sustainable business model, more evaluation and research is required around suitable areas of use.

Approach and implementation

Sending MIBA to Switzerland for treatment resulted in data on the composition of the Swedish slag. Chemical tests made it possible to further define how the fractions should be handled. Investigation of possible applications and legal potential yielded insights that the recycling process is complex and probably requires cooperation with relevant industries and authorities. A more accurate economic and environmental assessment of the method is needed. Other solutions to utilize the slag may be more feasible if the sorting residue in the future ends up in landfill.