Mapping of critical raw materials in bauxite mining residues using geostatistics and remote sensing
Authors: Sara Kasmaeeyazdi1, Adriana Guatame-Garcia2, Francesco Tinti1, Mike Buxton2, Emanuele Mandanici1, Joachim Schick3, Francoise Bodenan4, Dimitris Sparis5, Elefthymios Balomenos6, Roberto Bruno1
1Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, Bologna, Italy
2Department of Geosciences and Engineering, Delft University of Technology, Delft, Netherlands
3Innovation Center for Extractive Metallurgy, Orano Mining, Bessines-sur-Gartempe, France
4Bureau de Recherches Géologiques et Minières, BRGM, Orléans, France
5National Technical University of Athens, Athens, Greece
6Mytilineos S.A., Agios Nikolaos, Greece
Keywords:Bauxite mapping; Hyperspectral images; Band ratio
Abstract: In remote sensing analysis, bands information and indices are used to map different regionalized variables, for different applications of earth and environmental sciences. Moreover, the classifications methods can be used to differentiate the areas, and then with kriging tools to estimate the target variable values and variances. Often, these analyses are enriched by the validation of the obtained estimation maps using values from in-situ samples. On the other hand, to get effective and reliable maps, there is the need of high amount of data. In this
research, remote sensing studies (statistical studies, spectrum view and unsupervised classifications) applied to Copernicus Sentinel-2 images have been combined with advanced geostatistical approaches (Gaussian simulation using Turning Bands -TBs- algorithm) to map the distribution of one critical raw material (Vanadium element-V2O5). The approach has been applied to a Bauxite tailings case study in Greece. Simulation results have been obtained for the Vanadium grade variability maps in the Bauxite tailings for 1000 realizations using infield samples as direct and Sentinel-2 images as an auxiliary variable. To test the simulation results, the reproduced experimental variograms of the realizations are compared with the selected
variogram model of the Vanadium concentration and they have shown a coherent convergence. Hence, despite the lack of band-ratio existence for Vanadium identification in remote sensing analysis and, on the other hand, the limited number of initial sampling of data for geostatistical analysis, the integration of both approaches has generated appropriate maps of Vanadium grade distribution, within the Bauxite tailings case study.
Oral Presentation: 14th International Conference on Geostatistics for Environmental Applications - GeoEnv2022, 22-24 June 2022, Parma, Italy,
Mapping bauxite mining residues using remote sensing techniques
Authors: Sara Kasmaeeyazdi1, Roberto Braga2, Francesco Tinti1, Emanuele Mandanici1
1Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, Bologna, Italy
2Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna, Italy
Keywords:Bauxite mapping; Hyperspectral images; Band ratio
Abstract: Bauxite residuals from abandoned mining sites are both an environmental challenge and a possible source of secondary raw materials. Processing of multispectral and hyperspectral images with the best available techniques can help to produce multiscale spatial maps of elements inside and around the mining sites. Authors propose a procedure for mapping elements concentration using multiple data sets at different scale and resolution. A comparison between multispectral Sentinel-2 images and hyperspectral PRISMA processing is performed over some case studies of bauxite residues in the Mediterranean area. Specifically, a case study from Italy is composed by artificial canyons created by past artisanal mining activities and by stockpiles of extracted bauxite. Hyperspectral punctual measurements (spectro-radiometer surveys) were taken in various zones of the bauxite site, where also infield topsoil samples were taken for X-Ray fluorescence chemical analysis. Final concentration maps were estimated by performing geostatistical techniques.
Oral Presentation: International Conference on Raw Materials and Circular Economy - RawMat2021, 06-09 September 2021, Athens, Greece
Open access Conference Paper, Materials Proceedings, Volume 5(1), 91, January 2022
The future of scandium recovery from wastes
Authors: Olga Chernoburova1, Alexandre Chagnes2
1Université de Lorraine, GeoRessources laboratory, France
2Université de Lorraine, CNRS, GeoRessources laboratory, France
Keywords: Scandium, Mining Residues, Critical Raw Materials
Abstract: With growing demand for renewable and clean energy technologies, the need in rare earth metals is increasing. Scandium, which is often considered as a rare earth element (REE), is a critical metal used in aluminum alloys, for automotive, aerospace, defense and renewable energy industries (European Commission, 2020). The metal’s scarcity is justified by its limited world production that is mostly concentrated in China (66%), Russia (26%) and Ukraine (7%) (Dittrich and Yagmurlu, 2018). Economic concentrations of scandium in primary ores are rare. In order to secure EU supply of the metal it is important to identify its potential alternative sources, as well as the technologies suitable for the metal recovery. According to the study of Gaustad et al. (2021), the most promising scandium-rich residues include: ashes, generated during coal combustion and bauxite residues, containing on average 2.9 and 11.6 times the average concentration of scandium in ores, respectively. For some of these wastes, scandium content is associated with high variability when wastes of different origin are compared, whereas for other wastes such variability manifests to a lesser extent. Nevertheless, despite the attractive concentrations and large available tonnage of the residues, extraction of scandium from these materials presents a technological challenge. An extensive research work has been and is currently being conducted on the extraction of REE from wastes; however, the majority of methods and technologies under development are characterized with low TRL. Another important issue that has to be addressed is the price volatility of scandium and potential influence of an emerging alternative stream of metal on its market price. It is thus important to identify a strategy allowing economically secure recovery of scandium from wastes. In this work, recently developed methods and technologies for scandium extraction from wastes are reviewed and discussed. The major problems associated with scandium production from the above-mentioned wastes are addressed. The review concludes with highlights and perspectives.
Oral Presentation: International Conference on Raw Materials and Circular Economy - RawMat2021, 06-09 September 2021, Athens, Greece
Open access Conference Paper, Materials Proceedings, Volume 5(1), 55, December 2021
Best practices for characterising mine wastes towards a mineral recovery assessment: a concept
Authors: Mike Buxton1, Adriana Guatame-Garcia1, Francesco Tinti2, Sara Kasmaee2
1Department of Geosciences and Engineering, Delft University of Technology, Delft, Netherlands
2Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, Bologna. Italy
Keywords: mine wastes, mineral recovery optimisation, holistic overview
Abstract: In response to the growing strategic and economic interest in sourcing minerals from mining residues, the industry is increasingly developing practices to optimise mineral recovery. Some of the challenges lies in characterising the spatial and volumetric distribution of the waste components and upscaling geochemical and mineralogical data from microscopic to deposit-scale observations. This work introduces a conceptual framework for the geochemical and mineralogical characterisation of mine wastes that can support the successful recovery of residual and secondary ores. The basis of this framework is a combination of laboratory analyses, in-the-field surveys and remote sensing techniques integrated through machine learning and artificial intelligence techniques. The output of this framework is a toolbox that provides a holistic overview of the components inside a waste deposit and their distribution that generates information about the presence of recoverable ore.
Oral Presentation, Sustainable Minerals '21, 21-24 June 2021 | Online
Challenges in the sampling and characterisation of mining residues for CRMs recovery
Authors: Adriana Guatame-Garcia1, Mike Buxton1, Sara Kasmaee2, Francesco Tinti2, Rachel Horta Arduin3, Aina Mas Fons3, Francoise Bodenan4, Joachim Schick5
1Department of Geosciences and Engineering, Delft University of Technology, Delft, Netherlands
2Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, Bologna. Italy
3Université de Bordeaux, Bordeaux, France
4Bureau de Recherches Géologiques et Minières, BRGM, Orléans, France
5Innovation Center for Extractive Metallurgy, Orano Mining, Bessines-sur-Gartempe, France
Keywords: Round Table, sampling, characterisation, mining residues
Abstract: 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.
Oral Presentation, virtual European Geosciences Union (vEGU) Conference, 30th April 2021
Mine waste reuse and reprocessing: an important step for the implementation of the circular economy in Europe
Authors: Françoise Bodénan1,Yannick Ménard1, Patrick d'Hugues1
1Bureau de Recherches Géologiques et Minières, BRGM, Orléans, France
Keywords: mine wastes, circular economy, secondary sources
Abstract: 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.
Oral Presentation, virtual European Geosciences Union (vEGU) Conference, 30th April 2021
Valutazione preliminare in ottica di ciclo di vita della fattibilità di una filiera italiana del riciclaggio delle batterie elettriche per autotrazione
Authors: Cristian Chiavetta1, Marco La Monica1, Pier Luigi Porta1, Claudia Scagliarino2, Laura Cutaia1
1Laboratorio RISE – ENEA, via Anguillarese 301, 00123 ROMA
2CINIGeo – Consorzio Interunivesitario Nazionale per l’Ingegneria delle Georisorse Corso Vittorio Emanuele II, 244 - 00186 Roma
Keywords: Batterie elettriche, Material Flow Analysis, Filiera del riciclaggio, Fattibilità economica, Monetizzazione impatti ambientali
Abstract: L’affermazione di un modello circolare di produzione e consumo delle risorse necessita di interventi sull’attuale modello economico linerare a livello di prodotto-processo, catena del valore, settore produttivo oltre che a livello territoriale, tenendo conto delle interazioni tra i diversi sistemi produttivi. Il Laboratorio RISE di ENEA ha applicato in diversi contesti un approccio per la valutazione della fattibilità di sistemi di urban mining tramite un’analisi di scenario di medio-lungo periodo per la quantificazione dei flussi di materie prime seconde producibili ed una contestuale analisi della sostenibilità economico-ambientale. In questo articolo si propone la descrizione dell’applicazione di tale approccio metodologico alla valorizzazione delle batterie elettriche di trazione, includendo alcune considerazioni preliminari sulla monetizzazione delle esternalità ambientali, valutate tramite la metodologia del Life Cycle Assessment (LCA).
Oral Presentation, 14° convegno della Rete Italiana LCA 9-11 dicembre 2020, Cortina D'Ampezzo
Evaluating the correlation between ground information and satellite spectral data by geostatistical tools
Authors: Roberto Bruno1, Sara Kasmaee1,2, Francesco Tinti1, Emanuele Mandanici2
1Department of Civil, Chemical, Environmental and Materials Engineering, Sector Mining Engineering and Geostatistics - UNIBO, via Terracini 28, 40121 Bologna
2Department of Civil, Chemical, Environmental and Materials Engineering, Sector Geomatics - UNIBO, viale del Risorgimento 2, 40136 Bologna
Keywords: Satellite data, Geostatistics, Kriging of Components
Abstract: Satellite information opened new scenarios for planet surface mineral exploration. Hyperspectral information brought by sensors on board potentially help identifying and measuring concentrations of an element if an accurate calibration is done, based on available ground sampling. Most popular uses of satellite images refer to 2D problems and most calibrations refer to the spectral properties of the objects to be discovered and characterized (Follador M., 2005). Before calibration, images are affected by standard preprocessing, for instance for filtering unwanted effects, and for enhancing the information considered useful. The general problem for mineral exploration and reserves characterization is the spatial distribution of the target variable, with limited and sparse in situ information. Satellite images provide auxiliary information, which can be used, when correlation is found with the target variable. In this case the expected result should improve the estimation or the representation of spatial distribution of the sampled variable. Independently of the variable at hand (grades, discovery probability, …) and of the spatial distribution model (estimation, simulation), Geostatistics allows to tackle the central problem: finding meaningful correlations and modelling the unknown surface distribution of the interest variable by including satellite data as auxiliary information (Chiles et al., 2012; van der Meer, 1994). Three issues need attention when considering satellite images: a) the different support of direct and auxiliary information, being pixel data refereed to a surface, in contrast with the punctual ground data b) the need of 3D modelling c) the space-time nature of the satellite information. The correlation study is one of the most delicate phases when using satellite images for improving the models’ quality of surface distribution of a target variable. Geostatistics offers a wide variety of powerful tools for a deep study of these correlations. A short case study is reported as an example where it was identified the most correlated spatial component by a multivariate structural analysis.
Oral Presentation, Mineral Exploration Symposium, 17-18 September 2020 Online Event Proceedings
Application of geostatistical analysis interacting with the earth observation data for recovery of raw materials from mining residuals (stockpiles and tailings): research projects at University of Bologna.
Authors: Sara Kasmaee1,2, Emanuele Mandanici1, Francesco Tinti1, Stefano Bonduà1, Roberto Bruno1
1Department of Civil, Chemical, Environmental and Materials Engineering, Sector Mining Engineering and Geostatistics - UNIBO, via Terracini 28, 40121 Bologna
2Department of Civil, Chemical, Environmental and Materials Engineering, Sector Geomatics - UNIBO, viale del Risorgimento 2, 40136 Bologna
Keywords: Earth Observation, Geostatistics, Raw Materials, Recovery
Abstract: The poster presents an overview of the ongoing research projects at University of Bologna – DICAM Department, applying geostatistical methods to mining stockpiles and tailings with the purpose of metal recovery. The educational program RawMatCop of EIT Raw Materials is the main supporter of the research. The work takes advantage of the use of Earth Observation (EO) data for sampling optimization in mining residuals from abandoned and active mines. Purposes are both recovery of raw materials and environmental rehabilitation of tailing dams and landfills. EO can play an important role in accounting the raw material resources of a territory, since current satellites, such as the Copernicus constellations (Sentinels), provide continuous spatial and temporal coverage of the global at no cost. Thanks to the spatial resolution, Copernicus data can improve the characterization (quantification and evaluation) of a resource, together with the assessment of the associated risks. Moreover, EO can be used for continuous monitoring of the target areas, conditioned by mining activites. On the other hand, geostatistical analysis, using in situ sampling and EO images, exploit innovative methods to improve accuracy of grade and pollution maps, thus reducing the number of samples, with evident cost reduction. Test sites are bauxite residuals, located in Mediterranean Region: Greece and Montenegro (under analysis, 2019), Sardinia and Apulia (programmed work, 2020). Finally, a new international Project, INCO-Piles, starting in early 2020 and led by the research group, has the scope to identify the most promising mining residuals of Southern Europe for recovery of critical raw materials.
Poster session, Conference on Mining the European Anthroposphere, 20-21 February 2020, Bologna