Europe’s critical-minerals strategy is extending into existing metallurgical waste streams, with zinc-processing residues being assessed as a source of gallium, germanium and indium. Metallon Clean Extractions, a subsidiary of Zinc of Ireland, is developing the ARGO hydrometallurgical process to recover metals from zinc-leach residues.
The development programme has received a €734,000 VLAIO grant as part of a total €1.22 million programme. Zinc of Ireland is contributing approximately €489,000 over 24 months. Development is being conducted with KU Leuven’s SOLVOMET platform, while Nyrstar is participating through feedstock supply and industrial testing. A pilot stage is targeted for early 2027.
ARGO Targets Multiple Metals
The ARGO process is designed to recover zinc, lead and silver, alongside the minor metals gallium, germanium and indium. The latter metals are significant for European supply because domestic availability is limited, while they are used in semiconductors, optics and advanced industrial applications. The proposed feedstock has already passed through mining and part of the processing chain. Zinc-leach residue is located at existing industrial sites with infrastructure already in place, avoiding the need for a new mine, waste dump and haul road associated with a conventional mining development.
Hydrometallurgical Processing of Residues
The main technical challenge involves the chemistry of the material. Industrial residues contain complex combinations of metals and impurities, making recovery rates, reagent consumption and final product purity important factors in determining the commercial viability of the process. ARGO is being developed around the recovery of valuable metals from these existing refinery residues. If the targeted metals can be recovered economically, the process could provide an additional source of strategic mineral supply without requiring entirely new mining operations. The approach would treat some metallurgical waste streams as secondary mineral inventories, while using existing industrial sites and infrastructure as part of the recovery model.
