The European Union’s industrial future is currently tethered to a precarious dependence on external suppliers for the building blocks of the green transition. The RESiLEX project serves as a vital enabler, designed to de-risk the EU supply chain of critical raw materials by transforming mining waste from an environmental liability into a strategic asset. By establishing a circular secondary source, Resilex aligns directly with the 2030 CRMA mandate to secure 25% of annual consumption from recycled sources. This is not merely an ecological project; it is a geopolitical necessity.
The Treatment Train
Traditional mining waste management has historically been a “take-make-dispose” cost-centre, characterised by the discharge of acidic wastewater into ponds that pose perpetual environmental risks. The Resource Recovery (RR) Treatment Train represents a fundamental paradigm shift: it comprises an eight-unit system treating wastewaters and solid wastes from Tharsis Mining that splits the challenge into two complementary pathways. The following paragraphs describe the the Wastewater pathway of the Treatment train, developed by CETAQUA, and the solid pathway done developed by Tharsis Mining.
Wastewater pathway:
- Iron and aluminium removal — an initial physico-chemical step precipitates iron and aluminium together by neutralising the water to about pH 4.5 with caustic soda (NaOH).
- Anaerobic membrane bioreactor (AnMBR) — bacteria fed with an organic substrate (glycerol) generate the sulfide needed for metal precipitation, using the sulfate already present in the AMD as the electron acceptor.
- Sulfide precipitation — copper and zinc are recovered as copper and zinc sulfides (CuS, ZnS).
- Ion exchange (IEX) — selective resins retain cobalt and nickel.
- Acid recovery — nanofiltration concentrates cobalt and nickel and sulfuric acid is recovered for reuse within the train.
- Evaporative crystallisation — the concentrated stream is crystallised into cobalt and nickel sulfate crystals.
Video explaining the wastewater pathway
Solid-waste pathway:
- Thermal oxidation (roasting) — sulfur-rich solid waste is roasted in a rotary kiln to produce sulfur dioxide (SO₂).
- Sulfuric acid production — the SO₂ is converted into sulfuric acid (H₂SO₄), which feeds the ion-exchange step and closes the loop.
Targeted Recovery Matrix
| Extraction Technology | Recovered Compound | Primary Industrial Application |
| Physico-chemical Units | Iron (Fe) & alluminum (Al) | Potential re-use as an adsorbent |
| Sulfide Precipitation | Zinc sulfide (ZnS) & copper sulfide (CuS) | Intermediate concentrates for metallurgical sectors and potential pigments/coatings (ZnS) |
| Evaporator-Crystallizer | Cobalt & nickel sulfate hydrates (CoSO₄·xH₂O, NiSO₄·xH₂O) | Battery Grade precursors |
| Electrolysis/Refining | Sulfuric acid (H₂SO₄) | Internal re-use or Fertilizers |
[Download deliverable … ]
Economic scenarios: high purity as a catalyst for profitability
In the circular economy, technical efficiency is a stranded asset without a clear path to bankability. The economic modelling performed, demonstrates that financial viability is intrinsically linked to chemical refinement. The project evaluated two distinct trajectories, considering the upscaling of the RR treatment train to 50 m3/h at Tharsis Mining:
- Scenario I (Low Intervention): Recovered compounds are sold as raw concentrates to intermediate smelters. While this achieves basic regulatory compliance, the operating margins are narrow, yielding only €45,540 per year.
- Scenario II (High Profit/Grade A): By integrating advanced refining stages, specifically solvent extraction and meticulous pH adjustment, the system produces “Grade A” materials. This scenario generates a 295% increase in net operating margin, reaching €179,978 per year.
Achieving “Grade A” status is not a luxury; it is a regulatory requirement for market entry. High-purity products (>99.5% for cobalt sulphate and >99.99% for zinc sulphide) are the only way to satisfy REACH, CLP, and the General Product Safety Regulation (GPSR 2025) traceability and batch documentation mandates. This shift transforms waste remediation from a sunk cost into a high-margin industrial opportunity for the battery and optics sectors.
Environmental & Operational Risks
The LCA revealed that the hotspot for the climate change indicator and land use is the AnMBR, with more than 70% and almost 99%, respectively, of the total impact, while for the ecotoxicity freshwater the physico-chemical stage (including ultrafiltration) unit accounts for almost 97%. The climate change and land use results are explained for the yeast extract needed in the AnMBR, which requires agricultural production and large amount of energy to produce this reagent. On the other side, the presence of Fe in the waste stream in the first stage represents the main contributor for the ecotoxicity of freshwater.
This represents a significant strategic risk to the “End-of-Waste” status. However, this demand can be partially offset by the unit’s methane production. The pilot already used glycerol — a residue from the biodiesel industry — as its carbon source. Even so, this substrate is still not cheap, so improving long-term sustainability means exploring even lower-cost waste streams or alternative metabolic routes that reduce the organic demand of the process, further closing the circular loop.
Social Performance and Community Engagement
The S-LCA highlights a stark divergence between EU and global supply chains. While non-EU regions (specifically China) show “Very High Risk” in bargaining rights, strike freedom, and labor law violations, the European supply chain demonstrates superior human rights adherence. However, the EU model is not without flaws. Site-specific analysis of European firms reveals a failure in community engagement, specifically a lack of written policies for community involvement and the exclusion of local stakeholders from decision-making processes. Addressing these internal social gaps is essential for maintaining the “social license to operate” within Europe.
Webinar: Recovery of CRMs from mining waste
Securing the Future
The results achieved in RESiLEX provide a definitive blueprint for the future of the European silicon industry. We have demonstrated that the path to resource sovereignty is paved with the materials we once discarded. However, technological success must be matched by assertive policy, and here we are advancing some strategic recommendations:
- Mandatory Minimum Quotas: to provide the market certainty required for Scenario II investments, we recommend a 10% minimum quota for certified European secondary sources in all publicly funded battery and solar projects.
- Regulatory Harmonization: ensuring that recovered Grade A materials are fast-tracked for GPSR 2025 compliance to facilitate immediate integration into the Li-ion value chain.
By aligning the 295% profit potential of Grade A recovery with the 25% recycling targets of the 2030 CRMA, Resilex is building a technologically sovereign, socially responsible, and economically robust European industry. The transition from mining waste to high-tech value is no longer a pilot concept—it is a strategic imperative.