For more than 100 years the EU mining industries have been discarding their extractive-waste residues. Estimates suggest this represents 29% of the EU-28’s current waste output. When poorly managed these residues are a significant environmental hazard. Sulfidic Cu-Zn, Zn-Pb and Cu-Zn-Pb tailings pose the largest challenge, as they are prone to acid mine drainage. However, these tailings also contain valuable metals. Recently, the European Innovation Partnership (EIP) on Raw Materials launched a “call to arms” to transform the “extractive-waste problem” into a “resource-recovery opportunity”. Additionally, the EIP has warned about the acute shortage of talent in this sector. In order to develop a highly skilled workforce, to mitigate environmental risks and to economically recover valuable raw materials, the ETN for the remediation and reprocessing of sulfidic mining waste sites (SULTAN) provides the first-ever training programme dedicated to the reprocessing of tailings. SULTAN has pooled the interdisciplinary and intersectoral expertise of leading EIT RawMaterials members, world-leading mining and chemical companies, covering all the links in the tailings-reprocessing value chain. SULTAN develops cutting-edge methodologies to assess the resource potential of Europe’s main tailings families (WP1) and explores eco-friendly mining chemicals to be used in advanced metal-extraction/recovery set-ups (WP2). SULTAN not only recovers the metals but also valorises the clean(ed) tailing residues in circular-economy applications, incl. inorganic polymers, green cements and ceramics (WP3). In WP4 a novel environmental assessment methodology is developed. The 15 SULTAN ESRs also benefit from a unique soft-skills training programme (WP5) and maximise the impact of their research through dissemination and exploitation (WP6). This will kick-start their careers as highly employable professionals in the EU’s tailings reprocessing/remediation sector, as well as for geological surveys, teaching and scientific organisations, and public bodies.
Figure 1. SULTAN Consortium: 8 Beneficiaries and 7 Partner Organisations. Network-Wide Events (8), TSF & site visits (5) and access to research materials (tailings) (3) are shown, along with the EU-wide character of SULTAN and the link with EIT RawMaterials. The infographic highlights 10 key operational and closed mines in Europe that produce(d) Cu, Zn and/or Pb. The Freiberg Mining District and the Plombières mines are also shown as these historical mining regions provides two of the three main research materials in SULTAN.
SULTAN Feedstocks. In order to maximise the EU-wide applicability of the developed valorisation routes, the consortium has closely inspected the stocks and flows of tailings in Europe, in terms of mineralogical chemistry, metal content and EU-wide abundance. SULTAN has decided to focus on the tailings generated by the mineral processing of Cu-Zn ores, Zn-Pb ores and mixed Cu-Zn-Pb ores. The resulting tailings are not only different in terms of chemical composition (Figure 2a), they also contain, depending on the specific ore body, valuable metals, ranging from base, precious to critical metals such as In, Ge and Ga (Figure 2b). They also represent the largest volumes of tailings in Europe, and are widely available in countries like Sweden, Poland, Bulgaria, Portugal, Spain, Belgium and Ireland (see Figure 1)
Figure 2. (a) Average chemical composition of three targeted tailings, (b) Valuable (incl. critical6) metals addressed in SULTAN.
Figure 3. Overview SULTAN WPs and the supply-chain approach