Landfill mining from extractive waste facilities: The importance of a correct site characterisation and evaluation of the potentialities. A case study from Italy

Abstract

At present, little information is available on the opportunities and challenges to recover valuable critical raw materials (CRM) and secondary raw materials (SRM) from extractive waste (EW) deposits. In this study, an integrated framework describing the key steps required to assess the viability of CRM recovery from EW deposits is presented. The framework has been tested and validated using a pilot site located in the Northern region of Lombardy, Gorno. A tiered characterisation approach was used to support the framework and obtain information on (i) the deposit features and their characteristics including geocharacterisation of the waste layers, (ii) the physicochemical properties of the waste layers, and (iii) the presence of CRM/SRM hot spots using a combination of drone technology and geographic information system (GIS) data collection. Zinc (0.65 to 19.3 wt %) and Cadmium (22-544 ppm) and to a lower extent Gallium (6.0-88.6 ppm) were the most abundant elements that could be potentially recovered from the waste rocks. Assuming that all Zn, Cd and Ga were from exploitable minerals (eg. sphalerite, calamine, etc...), there are good opportunity of significant revenues ranging between 13.4 and 63 M€ for Zn, 18.5 and 88 k€ for Cd and 132 and 530 k€ for Ga. While caution is needed in extrapolating these potential revenues, there are promising and supporting the potential economic viability of landfill mining at EW deposits.

The Bargiolina, a Striking Historical Stone from Monte Bracco (Piedmont, NW Italy) and a Possible Source of Industrial Minerals

“…Preliminary data (XRD and XRF) on selected samples show a fair amount of kaolin and a very low Fe 2 O 3 content, suggesting a hydrothermal origin (quartz veins, presence of tourmaline) and a good suitability for the ceramic industry. Finally, the chance to exploit the other kaolinitic gneisses on the slopes of Monte Bracco should be further evaluated: If the reuse of quartzite waste and kaolin-rich gneisses are feasible, a more targeted field geological survey, physical, chemical and mineralogical characterization of the potential deposit and total volume estimation (field and GIS investigations) are recommended [16]. In the perspective of sustainable mining, it is important to move towards an integrated exploitation of the Monte Bracco area, with contemporary exploiting of the quartzite bench (second class material-quarrying activity), the quartzite waste and the kaolinitic gneisses (first class materials-mining activity for industrial minerals).…”

Assessment of the Possible Reuse of Extractive Waste Coming from Abandoned Mine Sites: Case Study in Gorno, Italy

“…Site description, which consists of collection of information about geology, mining, and processing activities (Section 2.1) [33] 2. Site investigation and sampling strategy (Section 2.2), which includes planned field survey to collect representative samples, define the investigating areas, evaluate waste characteristics, and estimate EW volumes [33] 3. Preparation of sub sample to be tested for RM/CRM recovery (Section 2.3)…”

“…The sampling was performed in dumps placed at Mount Arera ( Figure 3) following site investigation and sampling activities described in Dino et al [33] and here briefly reported. The WR dumps at Mount Arera are spread uniformly with thickness of c. 2 m. Waste rock material was sampled using a hand shovel and/or a hammer.…”

“…The mineralogical analysis of feed was not performed in this study, as it has been conducted on extractive waste from this site in a previous study by Dino et al [33], which indicated the presence of sphalerite in the WR. However, tailings contained minor amounts of Fe sulphate, Zn-silicate (hemimorphite), Zn-carbonate (smithsonite and/or hydrozincite), and rare Cu-As-Sb ± Pb sulphosalt(s).…”

“…Site investigation and sampling strategy (Section 2.2), which includes planned field survey to collect representative samples, define the investigating areas, evaluate waste characteristics, and estimate EW volumes [33]…”