ERE5.7

Towards an environmentally sustainable transformation of tailings and mine waste: circular economy and future vision

ERE5.7

Towards an environmentally sustainable transformation of tailings and mine waste: circular economy and future vision

Convener: Alexandra Escobar | Co-conveners: Rosie BlanninECSECS, Jens Gutzmer, Eric Pirard, Jorge Relvas

vPICO presentations

| Fri, 30 Apr, 11:00–12:30 (CEST)

vPICO presentations: Fri, 30 Apr

Chairpersons: Alexandra Escobar, Rosie Blannin

11:00–11:05

5-minute convener introduction

Characterization

11:05–11:07

EGU21-3257

ECS

Mineralogical Characterization, Resource Estimation and 3D Modeling of Sulfidic Tailings at the Neves Corvo Mine: An On-going Assessment

Alexandra Escobar, Jorge Relvas, Alvaro Pinto, and Mafalda Oliveira

Neves Corvo is an underground high-grade Cu-(Sn)-Zn mine, currently producing copper, zinc and lead concentrates. Copper production started in 1989, followed by tin production, between 1990 and 2001, and zinc / lead production started in 2006. The operation is owned by SOMINCOR, a subsidiary of Lundin Mining, with a maximum capacity of 2.6Mtpy for the copper processing plant and 1.0Mtpy (ongoing expansion to 5.6Mtpy) for the zinc processing plant.

The Neves Corvo VMS deposit is located in the Portuguese part of the world-class Iberian Pyrite Belt (IPB) and is composed of seven orebodies. The Neves, Corvo, Zambujal and Lombador orebodies are currently in production, whereas the Semblana and Monte Branco orebodies are relatively recent discoveries still under development and evaluation, and the Graça orebody has been already fully mined.

From 2010 till end of 2019, the mine has accumulated 7.3Mt of waste rock and 17Mt of thickened tailings. These mining residues are stored in Cerro do Lobo Tailings Management Facility (Cerro do Lobo TMF), which completes a volume of 47Mt since the beginning of the operation in 1989 (30Mt 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. The thickened tailings have an average of 63% solids. X-ray fluorescence analysis have shown copper and zinc grades variation in the waste rock between 0.3 and 0.9%, and 0.4% and 1.1%, respectively, and concentrations up to 0.3% and 0.4% of copper and zinc, respectively, in the tailings.

Mineralogically, the tailings consist mainly in pyrite, sphalerite, chalcopyrite, +/- arsenopyrite, +/- tetrahedrite-tennantite, 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, which include acid volcanic rocks, schists and graywackes, all of them containing variably significant disseminated sulfides, largely dominated by pyrite.

On-going research is being undertaken aiming to build a geometallurgical model for the Neves Corvo mine, ground on a huge database on the chemical and mineralogical composition, and particle size distribution of the mine tailings, coupled with (and calibrated by) new analytical and automated data acquired in a large set of carefully selected representative samples, in order to assess the potential recovery of base metals and their by-products out of these potentially valuable mine residues. The model construction and consequent resource estimation will be based on the daily monitoring of the tailings deposition at the disposal units, over the past 10 years (i.e., since the subaerial deposition has started at Neves Corvo), in terms of volume/tonnage, chemical and mineralogical compositions and physical characterization of the material.

This study is part of the work package 1 (WP1) of ETN–SULTAN project (H2020) - European Training Network for the remediation and reprocessing of sulfidic mining waste sites. Publication supported by FCT- Project UID/GEO/50019/2019 - Instituto Dom Luiz.

How to cite: Escobar, A., Relvas, J., Pinto, A., and Oliveira, M.: Mineralogical Characterization, Resource Estimation and 3D Modeling of Sulfidic Tailings at the Neves Corvo Mine: An On-going Assessment, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3257, https://doi.org/10.5194/egusphere-egu21-3257, 2021.

11:07–11:09

EGU21-9454

ECS

Mineralogical characterisation and deportment studies of different mine waste material from a historic tailings pond in Plombières, East Belgium.

Srećko Bevandić, Philippe Muchez, Rosie Blannin, Kai Bachmann, Max Frenzel, Alexandra Gomez Escobar, Álvaro Pinto, and Jorge M. R. S. Relvas

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 m², 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 SiO₂, Al₂O₃ and Fe₂O₃, 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.

How to cite: Bevandić, S., Muchez, P., Blannin, R., Bachmann, K., Frenzel, M., Gomez Escobar, A., Pinto, Á., and M. R. S. Relvas, J.: Mineralogical characterisation and deportment studies of different mine waste material from a historic tailings pond in Plombières, East Belgium., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9454, https://doi.org/10.5194/egusphere-egu21-9454, 2021.

11:09–11:11

EGU21-2992

ECS

A novel approach for the geospatial modelling and resource assessment of tailings storage facilities

Rosie Blannin, Max Frenzel, and Jens Gutzmer

Tailings are the fine-grained residues of ore processing operations, typically stored in dedicated tailings storage facilities (TSFs). Despite being viewed as ‘waste’ materials, tailings can contain significant amounts of valuable metals which were not recovered by original processing techniques or were previously not of economic interest. Re-processing of tailings deposits for the recovery of remaining metals has the additional benefits of mitigation of environmental hazards posed by the TSFs, such as Acid Mine Drainage (AMD). The estimation of mineral resources requires the construction of accurate and reproducible geospatial models. However, the sedimentary-style deposition and subsequent weathering of tailings results in a complex internal structure which is challenging to model, with a laterally and vertically heterogeneous distribution of the minerals comprising the residues. The present study investigates a novel approach for the geospatial modelling of a TSF case study. The surface of the tailings deposit was densely sampled in order to assess the intrinsic horizontal variability. Drill core samples were taken from a depth of 1-3 m, on a 30 m grid and nested grids of 15 m and 7.5 m, with additional random and twin holes. The entire depth of the TSF was sampled in 2 m intervals with a total of 10 drill holes to assess vertical variability. All drill core samples were analysed with x-ray fluorescence spectrometry and inductively coupled plasma mass spectrometry. The compositional data was log-ratio-transformed and variography and subsequent ordinary kriging and co-kriging were performed on the surface samples. The variogram models obtained for the surface samples were then applied for kriging of the deeper layers. Historical photographs of the surface of the TSF were used to improve estimates with co-kriging for the corresponding layers. The entire data set will be used to determine the most efficient sampling approach for the resource estimation of TSFs.

How to cite: Blannin, R., Frenzel, M., and Gutzmer, J.: A novel approach for the geospatial modelling and resource assessment of tailings storage facilities, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2992, https://doi.org/10.5194/egusphere-egu21-2992, 2021.

Re-use and Valorization

11:11–11:13

EGU21-4776

ECS

Environmental assessment of sulfidic mine waste and its integration into green construction materials

Jillian Helser and Valérie Cappuyns

Proper management and storage of mine waste (e.g., tailings and waste rock) is one of the main issues that mining industries face. Additionally, there is already an uncountable amount of existent historical mine waste, which may, even centuries later, still be leaching contaminants into the environment. One solution to minimize the risks associated with the waste, with also potential economic benefits, is through the valorization of the waste. This can be done by first recovering valuable metals and removing hazardous contaminants. Then, the remaining residue can be valorized into green construction materials, such as geopolymers, ceramics or cement. For some mine waste materials, such as those with only trace levels of metals, that are not economically viable to extract, the “waste” can be reused directly without this additional cleaning step. In the present study, mine waste originating from 3 different sites, both operational and historical mines, was characterized and assessed in comparison with the cleaned mine waste (i.e., cleaned by bioleaching or ion flotation methods) and with different types of green construction materials containing (cleaned and uncleaned) mine waste. Particular emphasis was given to the study of the mobilization of metal(loid)s from the mine waste and green construction materials (i.e., ceramics, geopolymers and cement) under different conditions, through a series of leaching tests (i.e., EN 12457-2, US EPA’s Toxicity Characteristic Leaching Procedure, and a pH-dependent leaching test). The standardized leaching tests were applied to either mimic neutral conditions in nature, conditions in a landfill (end of life), or a worst-case scenario (i.e., in extremely acidic or alkaline pH).

Mineralogical (X-ray diffraction) and chemical (X-ray fluorescence) characterizations of the original mine waste samples revealed high levels of Pb, Zn, and As in most samples. Additionally, the samples consisted mostly of quartz, micas, clay minerals and/or feldspars. Some samples also contained pyrite (FeS₂), a key mineral that generates acid mine drainage. Based on the leaching studies, some geopolymers, ceramics, and cement efficiently immobilized certain metals (such as Pb and Zn). Also, longer curing durations of the geopolymers in most cases improved the immobilization of metal(loid)s. Overall, the leaching studies revealed that the concentrations of mine waste incorporated in the construction materials, as well as the pH of those materials, were the main factors influencing the mobility of metal(loid)s. Additionally, for ceramics, the temperature at which the test pieces were fired, also played a major role. Through this detailed characterization, the environmental impacts were assessed from the mine waste to the downstream products, determining which valorization methods are the most viable to close the circular economy loop.

How to cite: Helser, J. and Cappuyns, V.: Environmental assessment of sulfidic mine waste and its integration into green construction materials, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4776, https://doi.org/10.5194/egusphere-egu21-4776, 2021.

11:13–11:15

EGU21-7639

ECS

Turning mine waste into a ceramic resource: Plombières mine tailing case

Francisco Veiga Simão, Hilde Chambart, Laure Vandemeulebroeke, Peter Nielsen, and Valérie Cappuyns

Mining and quarrying waste is considered the second largest waste stream in Europe. According to Eurostat, in 2018, this extractive waste accounted for over a quarter of all the EU-27 waste output (26.2%). The accumulation of this type of waste in tailing dams or waste rock piles, with no end-use, can pose as a significant environmental and health hazard as well as a resource loss. Sulphidic mine waste processing residues (tailings) pose a large challenge, as their content in hazardous metalloids and sulphates tend to become more chemically available, leading to the generation of acid mine drainage. Apart from the hazardous metalloids and sulphates, these mine tailings contain valuable base, precious and critical metals which can be used in different technological applications. Moreover, silicates and clay minerals are amongst the most common and abundant minerals in sulphidic mine tailings, which indicates that after pre-treatment, if necessary, they can be used in different ceramic building applications (e.g. roof tiles and blocks) for an increasing world’s population.

Plombières Zn-Pb inactive mine (Eastern Belgium), was exploiting an ore deposit between 1844-1882 and after closure of the mine, imported ores were smelted at the Plombières site until 1922. The dumped material from the mining operations consist of mainly mine waste and metallurgical waste, such as tailings and slags, from the processing plants. The goal of the present study is to evaluate the potential use of (uncleaned) Plombières tailing material in 3 different ceramic products (roof tiles, blocks and pavers), with different compositions and firing temperatures, taking into account production parameters, product quality and environmental compliance in Flanders (Belgium).

After a detailed physical, mineralogical, chemical, thermal and environmental characterisation of the Plombières mine tailing material, as well as of the replaced raw materials, one company-specific blend has been modified on a lab scale for each ceramic product, by partly or totally replacing some primary raw materials (mainly clay and sand) by 5%, 10% and 20% of Plombières fine tailing material. The shaping, drying and firing behaviour of lab test pieces was assessed and compared to the standard, as well as the required technical, aesthetical and chemical properties of each ceramic product. Furthermore, environmental compliance tests (column leaching test) were performed on the fired test pieces of all the ceramic products. The column leaching test is performed considering a 2^nd life scenario where shaped building products are demolished and can be recycled as granulates (non-shaped building products).

How to cite: Veiga Simão, F., Chambart, H., Vandemeulebroeke, L., Nielsen, P., and Cappuyns, V.: Turning mine waste into a ceramic resource: Plombières mine tailing case, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7639, https://doi.org/10.5194/egusphere-egu21-7639, 2021.

11:15–11:17

EGU21-8895

ECS

Opportunities related to Moroccan mine wastes valorisation

Yassine Taha, Rachid Hakkou, and Mostafa Benzaazoua

Large amounts of solid wastes are produced by the mining industry. These wastes are often considered as problematic materials as they can lead to harmful impacts on the surrounding environment and the society. However, it was proved by many studies that most of mine wastes are inert but sometimes mixed with problematic components such as sulfidic minerals and hazardous metals and metalloids. Reprocessing and retreatment of mine wastes is a key sustainable solution to remove the sources of pollution and to recover the remaining high value products. Many studies around the world have demonstrated the big interest in recovering the residual metals and the use of mine wastes in other applications such as the construction sector.

In this study, a special accent will be given to the current management practices of mine wastes in Morocco as well as the possible opportunities related to the reuse of mine wastes coming from different mining activities. Three main materials categories are targeted: phosphate waste rocks and tailings, coal waste rocks and zinc tailings. The goal is to suggest more sustainable management methods and to explore new future opportunities related to the re-use and reprocessing of these wastes. Some possible high value-added products from these types of wastes are suggested based on their characteristics, location and volume. Construction aggregates, ceramics, bricks, cement, glass, acid mine drainage control, and road-base construction are among the possible explored channels.

How to cite: Taha, Y., Hakkou, R., and Benzaazoua, M.: Opportunities related to Moroccan mine wastes valorisation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8895, https://doi.org/10.5194/egusphere-egu21-8895, 2021.

Mineral processing - recycling techniques

11:17–11:19

EGU21-3050

ECS

Flocculation as an Alternative to Increase the Recovery of Ultrafine Particles of Pyrite in Flotation of Tailings

Ana Luiza Coelho Braga de Carvalho, Feliciana Ludovici, Henrikki Liimatainen, André Carlos Silva, and Daniel Goldmann

Nowadays, flotation is the most commonly used method for mineral concentration. However, conventional flotation circuits are not suitable for ultrafine particles, and this is a challenge for the concentration of finely disseminated minerals. Moreover, tailing contain a considerable amount of very fine particles which can include valuable and hazardous minerals that have the potential to be recovered. Concern about ultrafine particles has increased as they are present in a wide variety of mineral pulps and can contain valuable minerals that have been lost to the tailings. Several alternatives have been proposed to improve the recovery of ultrafine particles in flotation, for example, decreasing the size of the air bubbles, column flotation, selective agglomeration of particles, etc. Among all, selective polymeric flocculation represents a promising option. The current study focuses on the use of polymeric flocculation to increasing the size of pyrite particles aiming to improve its recovery in the flotation of sulfidic tailings. Flocculation was performed with pyrite particles presenting P80 < 4 mm, in aqueous medium and alkaline conditions. Two polyacrylamides and a new nanocellulose-based chemical were used as flocculants. Microflotation tests were performed, without the addition of collector, to evaluate the formation of flocs through the reduction of the mechanical entrainment of pyrite after being submitted to flocculation.

How to cite: Coelho Braga de Carvalho, A. L., Ludovici, F., Liimatainen, H., Silva, A. C., and Goldmann, D.: Flocculation as an Alternative to Increase the Recovery of Ultrafine Particles of Pyrite in Flotation of Tailings, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3050, https://doi.org/10.5194/egusphere-egu21-3050, 2021.

11:19–11:21

EGU21-3298

ECS

Low-Energy Desalination Technologies for Treating Mining Effluents

Georgios Kolliopoulos

As our societies evolved and the quality of primary resources deteriorated, water use in process circuits has led to the generation of ever-increasing volumes of contaminated effluents. Despite the efforts for water recycling in process circuits, desalination technologies fail to treat solutions of high salinity, due to their focus on dilute solutions, such as seawater. The lack of energy efficient effluent desalination technologies leaves vast volumes of aqueous residues sitting in tailings ponds. This practice often allows oxygen to dissolve in water and oxidize certain elements, which leads to the generation of acid in a sequence of events known as acid mine drainage. Uncontrolled discharges resulting from such mining wastes have detrimental effects on the nearby water quality and aquatic ecosystems as well as on the health of the people of the local communities. In this work, we report on novel freeze desalination processes that can recover clean water from such industrial effluents in the form of ice at significantly lower energy compared to state-of-the-art desalination processes. Therefore, the developed technologies promise to economically and efficiently reduce the water-consumption related environmental footprint of the processing industry, the risks and liabilities associated with tailings ponds, as well as to secure access to safe clean water for nearby communities.

How to cite: Kolliopoulos, G.: Low-Energy Desalination Technologies for Treating Mining Effluents, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3298, https://doi.org/10.5194/egusphere-egu21-3298, 2021.

11:21–11:23

EGU21-12048

ECS

Combining bioleaching and brine-leaching in metal leaching processes: alternative to conventional

Tamara Azevedo Schueler and Daniel Goldmann

The recovery of valuable metals such as copper (Cu), zinc (Zn) and lead (Pb) from mine tailings has gained attention in recent years, mainly for the environmental risk of tailings storage facilities and the demand of such elements in different industrial sectors. Many sulphide tailings deposits are spread worldwide, and some of them belong to active mines, which produce tons of material per year. Leaching is a well-known technology for metal extraction. However, two aspects must be considered: the dissolution of metals involves the use of fresh water and, the tailings contain low metal concentrations and high impurities. As a result, leaching is too expensive due to energy input in water purification and high acid consumption. The use of salt water in mineral extraction processes is becoming more attractive in the mining sectors over the years, especially in regions where fresh water is scarce. The presence of salt water in metal leaching has demonstrated a great capacity to increase metal extraction from ore, for example, by increasing the surface and porosity of copper containing minerals. This phenomenon plays an important role in metal leaching. The formation of a passive layer on the surface of the mineral in oxidizing conditions is a strong barrier in the extraction of the target metal. Conditions that overcome this obstacle are of utmost importance for the mining industry. Furthermore, a combination of conventional leaching systems with biological methods (bioleaching) is shown to be a good strategy in tailings leaching. Bioleaching has been applied to the treatment of poor ores and tailings, since acidophilic bacteria can oxidize Fe²⁺ with the regeneration of Fe³⁺ ions, together with the reduction of sulphur species to sulfuric acid, leading to the extraction of metals. Moreover, it is considered a more environmentally friendly technology than traditional extraction methods, as it occurs naturally, more economical and results in significantly less pollution. Therefore, some studies have been applying biological leaching as a pre-treatment for chemical leaching of mining tailings. The aim of this work is to present and discuss possibilities to conventional metal extraction processes, combining the two strategies of bioleaching and brine-leaching.

How to cite: Azevedo Schueler, T. and Goldmann, D.: Combining bioleaching and brine-leaching in metal leaching processes: alternative to conventional, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12048, https://doi.org/10.5194/egusphere-egu21-12048, 2021.

11:23–11:25

EGU21-12333

ECS

Functionalized nanocelluloses as bio-based chemicals in froth flotation

Feliciana Ludovici, Ana Luiza C.B. de Carvalho, Robert Hartmann, and Henrikki Liimatainen

Froth flotation is the most common process in the mining industry for the beneficiation of complex sulfide ores. For this purpose, thiol collectors (mostly xanthates) are typically used as flotation chemicals because of their efficacy. However, concerns for their effect on human health and negative impact on the environment increasingly urge for alternative candidates. Consequently, there are great ecological and economical interests to develop novel green chemicals from renewable resources to overcome the inherent environmental and health problems associated with traditional petroleum-derived mining chemicals. Cellulose, which is the most abundant natural polymer resource, represents a green alternative raw material to develop sustainable chemicals that could replace currently used synthetic additives. In the present work, we introduce a novel environmentally friendly and industrially feasible process to produce selective froth flotation chemicals. Therefore, the pulp fibers were disintegrated to cellulose nanoparticles and further functionalized with a silylation reaction in aqueous conditions. Two different functional groups were incorporated into the cellulose nanoparticles and subsequently investigated, namely a thiol-functional moiety, which has an affinity towards pyrite ore surfaces, or an amine-functional moiety, which has an affinity towards silica surfaces. Microflotation tests were carried out in a Hallimond tube to study the flotability of pure pyrite or quartz as a function of pH value, collector concentration, flotation time, and gas flow rate using the novel green nanoparticles, and their results were compared with commercial xanthate and amine chemicals.

Keywords: cellulose nanoparticles, deep-eutectic solvent, silylation, ore beneficiation, froth flotation.

How to cite: Ludovici, F., C.B. de Carvalho, A. L., Hartmann, R., and Liimatainen, H.: Functionalized nanocelluloses as bio-based chemicals in froth flotation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12333, https://doi.org/10.5194/egusphere-egu21-12333, 2021.

Challenges

11:25–11:27

EGU21-10617

Sustainable Development Goal Conflicts in Re-Mining of Tailings

Philipp Büttner, Jens Gutzmer, Jonathan Engelhardt, and Mirko Martin

The Davidschacht tailings storage facility (TSF), operated from 1944 to 1964, represents one of the largest tailings dams in the historic Freiberg mining district. It contains a volume of 760,000 m³ of sulfidic flotation tailings, residues of former base metal and silver ore beneficiation. The tailings material still contains elevated concentrations of valuable elements such as zinc (0.4 wt.% on average), lead (0.2 wt.%) and copper (0.05 wt.%) as well as indium (10 ppm). The material has thus become the focus of efforts to enable eventual re-mining and recovery of valuable metals. However, such efforts have to take into account a number of important interests of the public. The first of these is the fact that the unrehabilitated tailings pose a significant risk to the environment. Cd (44 ppm on average) and As (0.6 wt.%) concentrations are particularly high – and have a marked influence on the adjacent water bodies, such as the Freiberg Mulde river. Curbing this influence has been the subject of multiple remediation studies, but pressure to act has risen recently due to increasing regulatory demands on the quality of surface water (EU Water Framework Directive of 2000). This is, in principle, very much in favor of re-mining the tailings in an effort to remove also hazardous components. Counteracting this reclamation scenario is the fact that the TSF is part of the UNESCO World Heritage Site “Erzgebirge / Krusne Hory” that was awarded in 2019. Another restriction pertains to the highly protected status of individual species (esp. sand lizard) settling on the TSF surface. This constellation obviously provides ample space for discussion as to how to deal with the tailings material contained in the Davidschacht TSF in future. Different sustainable development goals (SDG) have to be weighed against each other in order to find a holistic and sustainable. Airlift reactor-based bioleaching has been considered as an opportunity to maximize the sustainability of re-mining activities on the Davidschacht TSF. This innovative approach – and its circumstantial limitations – are documented in this contribution.

How to cite: Büttner, P., Gutzmer, J., Engelhardt, J., and Martin, M.: Sustainable Development Goal Conflicts in Re-Mining of Tailings, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10617, https://doi.org/10.5194/egusphere-egu21-10617, 2021.

11:27–11:29

EGU21-4734

ECS

Challenges in the sampling and characterisation of mining residues for CRMs recovery

Adriana Guatame-Garcia, Mike Buxton, Sara Kasmaee, Francesco Tinti, Rachel Horta Arduin, Aina Mas Fons, Francoise Bodenan, and Joachim Schick

The recent Circular Economy Action Plan for Europe¹ considers mine waste a secondary source of minerals. These deposits contain potentially economic concentrations of Critical Raw Materials (CRMs), such as Al, Li, Co and REE, which are strategic for the global economy and energy transition. However, there are significant knowledge and technological gaps that hinder their successful recovery. The INCO-Piles 2020 project² is currently working on the recapitulation, establishment and development of innovative technologies for the sustainable extraction of CRMs from the residuals of mining activities, focusing on Regional Innovation Scheme (RIS) strategic areas. The project includes the definition of potential applications, best practices, and the promotion of technology transfer through round tables that count with international experts' participation.

The first Round Table, a hybrid event held in December 2020 with 73 experts from 23 countries, addressed the challenges in recovering CRMs from tailings. The discussions were based on three topics: (1) challenges in sampling and characterisation from mining residue, (2) extraction and processing challenges, and (3) economic and environmental challenges. Regarding the first topic, one of the most significant issues is the inherent heterogeneity of mine waste deposits, which is a product of the mine processing and deposition methods, and the post-depositional weathering reactions. The lack of historical data, particularly for old deposits, hampers the understanding of such processes. A second challenge concerns the specific type of information required for assessing the CRMs potential. Representative geochemical and mineralogical data must be collected and interpreted at different scales (i.e., from individual minerals to tens of meters tall waste rock piles and tailings). The collection of representative samples faces issues related to the accessibility to the mine waste sites, the coverage and the sample contamination (i.e., material mixing) related to sample recovery methods. The scalability can be addressed by a combination of laboratory analyses, in-the-field surveys and remote sensing techniques. Current innovations in the combination of modern analytical instruments for geochemistry and mineralogy (e.g., pXRF, LIBS and portable infrared spectrometers) and the implementation of machine learning and artificial intelligence techniques will contribute to closing the knowledge and technology gaps.

Lastly, the discussions included the potential hazards faced during the characterisation and re-intervention of old-sites. Well-known mine wastes issues related to human health, environment and license to operate that can hinder a characterisation campaign must be properly considered before the commencement of a CRMs recovery project. The participants also identified transversal challenges for the three discussion topics, such as the need for regulation and professionals with an appropriate background.

All the insights discussed during this First Round Table will serve as a baseline for defining the best practices for characterisation and sampling of CRMs in mine wastes and contributing to increasing the sustainability in the supply of mineral resources and improving old mining sites' environmental quality.

¹ EU Circular Economy Action Plan https://ec.europa.eu/environment/circular-economy/

² INCO-Piles is a two-year project funded by EIT RawMaterials. More information: https://site.unibo.it/inco-piles-2020/en

How to cite: Guatame-Garcia, A., Buxton, M., Kasmaee, S., Tinti, F., Horta Arduin, R., Mas Fons, A., Bodenan, F., and Schick, J.: Challenges in the sampling and characterisation of mining residues for CRMs recovery, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4734, https://doi.org/10.5194/egusphere-egu21-4734, 2021.

11:29–11:31

EGU21-7764

Highlight

Mine waste reuse and reprocessing: an important step for the implementation of the circular economy in Europe

Françoise Bodénan, Yannick Ménard, and Patrick d'Hugues

Whereas there are growing needs for mineral resources (metals for the energy and digital transitions
and construction materials), the mining industry must produce them from poorer, more
heterogeneous and more complex deposits. Therefore, volumes of mine waste produced (including
tailings) are also increasing and add up to waste from mining legacy. For example in Europe (x27): 732
Mtons of extractive waste are generated per year and more than 1.2 Btons of legacy waste are stored
all over the European territory. The localisation (and potential hazards) are well known and covered
by the inventories carried out in EU countries under the Mining Waste Directive.
At the same time, Europe is implementing the circular economy approach and put a lot of emphasis
on the resource efficiency concept. In this context, reprocessing operation to recover both metals and
mineral fraction is studied with the objective of combing waste management (reducing final waste
storage and long-term impact) and material production from secondary resources.
Numerous industrial experiences of reprocessing of mine waste and tailings exist all over the world to
recover metals such as copper, gold or critical raw materials - CRM They concern mainly active mine
where both primary and secondary resources are considered in profitable operations; for example in
Chile, South Africa, Australia. Mineral fraction recovery is often not considered which still leaves the
industry with a high volume of residual minerals to store and manage.
In addition, legacy mining waste are potentially available for reprocessing. In this case, numerous
mining liabilities issues need to be managed. Some of the European legacy mining waste have residual
valuable metals that could be recovered but some of them have very low metal contents. In Europe,
classical rehabilitation operations – usually at the charge of member states and local authorities – is
the priority and concern the reduction of instabilities and impacts to the environment including heap
remodelling, covering and water management with long-term treatment. Completing this risk
management approach by a circular economy one is a very active R&D subject in EU27.
This presentation will give an overview of EU research projects which tackled the legacy mining waste
challenge from inventory to process development. Several process flowsheets to recover metals were
designed and tested on several case studies with CRM – REE, Co, W, Sb, etc. Initiatives to reuse mineral
fraction are also underway and should be ready for commercialisation in the coming years.
Resources efficiency concept and the circular economy implementation starts on mining sites. In order
to facilitate the implementation of this approach, the technical solutions will need to be included in
innovative global initiatives covering also legal (liability management), environmental (Life Cycle
Analysis approaches) and social (acceptance) questions.

How to cite: Bodénan, F., Ménard, Y., and d'Hugues, P.: Mine waste reuse and reprocessing: an important step for the implementation of the circular economy in Europe, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7764, https://doi.org/10.5194/egusphere-egu21-7764, 2021.

11:31–11:33

EGU21-4027

Legacy deposits: can a small-scale mining paradigm contribute to the re-processing mining wastes to supply critical raw materials?

Jérôme Bodin, Guillaume Bertrand, and Patrick D'Hugues

In line with the perspective of the Raw Material Initiative launched in 2008 by the European Commission to ensure access to and supply of critical raw materials in Europe, the H2020-funded IMPaCT project (Grant no. 730411) aims to develop a Switch-On Switch-Off (SO-SO) concept as an emergence of a new modern small-scale mining paradigm. Its ultimate goal is to increase the viability of many critical metals hosted in small primary deposits, particularly in Europe, by developing a modularized mobile plant (MMP) concept that can economically operate different type of ores in different types of geological and geographical contexts.

In addition, the project addresses the prospect of applying the SO-SO concept and the small-scale mining paradigm with regard to the reprocessing of mineral wastes in Europe. A dataset of legacy deposits of interest for the SO-SO concept was drawn from the ProMine Anthropogenic Concentration (AC) database (built during the European FP7 ProMine project) used as the data source and by applying a sequential-rating as a methodology to rank records and to highlight potential targets.

Apart from national mining wastes registries, the ProMine AC database remains so far the most exhaustive and reliable attempt at a consolidated pan-European database regarding mining wastes. Despite data shortcoming in the ProMine AC database, this study proposes potential targets of mineral wastes for the SO-SO concept in Europe and provides with preliminary information on location, type of waste, commodities content, tonnage and their potential.

To put into perspective the application of the SO-SO concept and the small-scale mining paradigm in regards with mineral wastes reprocessing, this study also proposes generic flowsheets to address specific potential targets identified among the records from the ProMine AC database and based on the preliminary information available. However, the relevancy and completeness of these information still require a case-by-case assessment. As a result, this methodology falls into a scoping approach that could be applied ahead of (pre)feasibility studies.

Combining the re-exploitation of a primary ore deposit along with the reprocessing of its wastes inherited from previous mining and ore processing activities is of great interest in seeking social acceptance. Eventually, in such perspective, a cross survey of the potential of both primary deposits, using the ProMine Mineral Deposits (MD) database, and secondary deposits, using the ProMine AC database, therefore appears as a relevant scoping strategy ahead of implementing small-scale mining.

How to cite: Bodin, J., Bertrand, G., and D'Hugues, P.: Legacy deposits: can a small-scale mining paradigm contribute to the re-processing mining wastes to supply critical raw materials?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4027, https://doi.org/10.5194/egusphere-egu21-4027, 2021.

11:33–12:30

Meet the authors in their breakout text chats