Neves Corvo is an underground high-grade Cu-(Sn)-Zn mine, located in the Portuguese part of the world-class Iberian Pyrite Belt (IPB), which is currently producing copper, zinc, and lead concentrates. The operation is owned by SOMINCOR, a subsidiary of Lundin Mining, with a maximum capacity of 2.6 Mtpy for the copper processing plant and 1.0 Mtpy for the zinc processing plant. From 2010 till end of 2019, the mine has accumulated 7.3 Mt of waste rock and 17 Mt of thickened tailings. These mining residues are stored in Cerro do Lobo Tailings Management Facility (Cerro do Lobo TMF), which completes a volume of 47 Mt since the beginning of the operation in 1989 (30 Mt are slurry tailings). The deposition method changed in 2010 from slurry subaquatic deposition to sub-aerial thickened tailings stack (vertical expansion) in co-deposition with potentially acid-generating (PAG) waste rock. X-ray fluorescence analysis have shown copper and zinc grades variation in the waste rock between 0.12 and 0.4%, and 0.1% and 0.3%, respectively, and concentrations up to 0.6% and 1.3% of copper and zinc, respectively, in the tailings. Mineralogically, the tailings consist mainly in pyrite, sphalerite, chalcopyrite, ± arsenopyrite, ± tetrahedrite-tennantite, and gangue minerals such as quartz, phyllosilicates, carbonates, and some oxides, and have a non-uniform particle size distribution ranging between 1 and 100 µm. The waste rock fraction is millimetric to centimetric in size and is formed by the local host rocks, mineralogically consisting in quartz, chlorite (clinochlore and chamosite), calcite, and variably abundant disseminated sulfides, largely dominated by pyrite. Both mining residues might be envisaged as materials with valorization potential both for base metal recovery (tailings) and/or as non-metallic raw materials for construction or other applications (waste rock).The contributing editor for this article was Max Frenzel.

Sulfidic mining waste rock is a side stream from the mining industry with a potential environmental burden. Alkali activation is a promising method for transforming mining waste into construction materials. However, the low reactivity of minerals can be a sizeable challenge in alkali activation. In the present study, the reactivity of waste rock was enhanced by mechanochemical treatment with a LiCl-containing grinding aid. X-ray diffraction (XRD) and diffuse reflectance infrared Fourier transform (DRIFT) analysis were utilized to display the structural alteration of individual minerals. A schematic implication of the grinding mechanism of mica was provided according to the results of transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The alkaline solubility displayed the enhanced chemical reactivity of the waste rock, in which Si and Al solubility increased by roughly 10 times and 40 times, respectively. The amorphization of aluminosilicate is achieved through chemical assisted mechanochemical activation. Sulfidic waste rock, as the sole precursor in alkali activation, achieved a 28-day compressive strength exceeding 10 MPa under ambient curing conditions. The simulation of the upscaled grinding process was conducted via the HSC Chemistry® software with a life-cycle assessment. The results showed that mining waste rock can be a promising candidate for geopolymer production with a lower carbon footprint, compared to traditional Portland cement. Graphical Abstract

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<p>Recent studies on historic mine waste (e.g. tailings, waste rock, metallurgical waste) indicate the recycling potential of the material for metal extraction. Historic mine wastes have been shown to be of more interest than modern mine wastes, due to the lower efficiency of ore processing in the past. Although the knowledge of processing has significantly improved, there are still some areas in the processing sector that could be improved. Most previous studies have focused on the bulk analysis of mine wastes, without a detailed analysis of important characteristics, such as mineral texture, associations, liberation and locking. Recent studies focus on detailed mineralogical analysis, in order to more accurately assess the availability of the metals within the potential material for metal extraction. The present study investigates the geochemical and mineralogical characteristics of different mine and metallurgical waste material from a tailings pond in Plombières (East Belgium). The tailings pond covers a minimum surface area of 8000 m<sup>2</sup>, comprising 4 main types of material.  Ore microscopy, X-ray fluorescence (XRF), quantitative X-ray powder diffraction (XRD), scanning electron microscope (SEM) based Mineral Liberation Analysis (MLA) and electron microprobe (EPMA) were used to identify and characterise Pb and Zn phases within the material. XRF analysis shows that the mine wastes dominantly consist of SiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub> and Fe<sub>2</sub>O<sub>3</sub>, while the content of Zn and Pb varies from 51 ppm to 24 wt % and 10 ppm to 10.1 wt %, respectively. The mineralogy of the mine waste is characterised by quartz, amorphous phases and phyllosilicates, with minor amounts of Fe-oxide, Pb- and Zn-bearing minerals. Based on the processing of the ore, the amorphous phase is present as pyrometallurgical slag.  Mineral- to element- conversion shows a lack of Pb and Zn content. MLA and EPMA analysis confirm that the missing Pb is distributed between Pb- droplets within the slags and in the amorphous structure of the slags. Additionally, the analyses reveal that zinc is also dominantly located within the slags.</p>