The Closing the Loop project involves Aurubis AG, an expert in multi-metal recycling, and GRILLO-Werke AG, a specialist in zinc chemistry. Together, they efficiently recycle valuable metals such as copper and zinc.

The recycling process at Aurubis AG produces copper cathodes from recycling raw materials. GRILLO-Werke use the zinc-rich oxide produced in the process as a raw material for the production of zinc sulphate. When GRILLO processes the filter dust into zinc sulphate, a residue accumulates that contains other valuable ingredients such as copper, tin and lead in an enriched form. Aurubis AG takes back this residue, recovers the metals as products and thus closes the recycling loop.