GMPV6.1 | Critical metals and minerals from mining and quarrying waste materials: formation, recovery and environmentally sustainable management for their valorization.
EDI
Critical metals and minerals from mining and quarrying waste materials: formation, recovery and environmentally sustainable management for their valorization.
Co-organized by ERE4
Convener: Antonello AquilanoECSECS | Co-conveners: Elena Marrocchino, Giovanna Antonella Dino, Angel M Lopez-Buendia, Stefan Dirlich
Orals
| Mon, 15 Apr, 08:30–10:10 (CEST)
 
Room -2.33
Posters on site
| Attendance Mon, 15 Apr, 16:15–18:00 (CEST) | Display Mon, 15 Apr, 14:00–18:00
 
Hall X1
Posters virtual
| Attendance Mon, 15 Apr, 14:00–15:45 (CEST) | Display Mon, 15 Apr, 08:30–18:00
 
vHall X1
Orals |
Mon, 08:30
Mon, 16:15
Mon, 14:00
The production of minerals and metals is projected to increase by almost 500% by 2050 in order to meet climate targets and the growing demands of society and industry. The extraction and processing of geological resources inevitably generate a significant amount of waste throughout the extraction and processing stages. Waste from quarrying and mining contains substantial quantities of residual minerals, including critical raw materials (CRMs) such as metals and rare earth elements (REE). These waste materials have the potential to be valuable mineral resources.
In the past, the primary focus of mining and mining waste management was on addressing environmental risks and landscape degradation. However, advancements in innovative and technological processes now allow us to reduce, reuse, and recycle these industrial residues, promoting more sustainable exploitation practices. Nevertheless, there are additional challenges associated with the exploration, characterization, recovery, reprocessing, and testing of these recovered materials. Furthermore, it is crucial to develop realistic models for mining waste to accurately assess the prospects for sustainable utilization.
The main topics to be discussed in this session address, but are not limited to:
-Sustainable quarry and mine waste management strategies
-Innovative tools and enhanced methodologies in active and legacy sites for environmental/risk monitoring
-Identification of potential secondary resources (e.g., REEs, CRM)
-Characterisation of geomaterials, their environmental interactions and decay
-Technological developments for waste sampling, characterisation and environmental assessment
-Innovative mineral exploration, extraction, and (re)processing technologies, including geometallurgy
-Mine waste sites rehabilitation and repurposing

Keywords: extractive waste; circular economy; sustainable mining; raw materials and critical raw materials characterization, mine waste management

Orals: Mon, 15 Apr | Room -2.33

Chairpersons: Antonello Aquilano, Elena Marrocchino, Giovanna Antonella Dino
08:30–08:35
08:35–08:45
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EGU24-652
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ECS
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Virtual presentation
Antonio Tazzini, Francesca Gambino, Marco Casale, and Giovanna Antonella Dino

Stone industry plays a significant role in the global economy. The 2015 production was placed in the order of 82.6 million tons with a percentage of the waste extraction and processing amount to over 70% of the gross quantity. Carbonate stones (such as marble, limestone and travertine) account for 58 % of the whole production of dimension stone, serving as primary materials for construction and ornamental uses since ancient times. Approximately 50% of waste is generated during mining operation and around 15% during processing. The disposal of marble powder, a very fine material produced by the marble industry, is one of today's global environmental problems affecting stone industry. Even if the ultra-fine calcareous particles contained in marble sludge have applications in most major industries, thanks to their chemical and physical characteristics, in most cases these materials are landfilled because of the difficulties in recovering, mainly related to local legislation and lack of appropriate protocols.
The need to reduce the use of non-renewable natural resources and, at the same time, to minimize the negative impacts on the environment, has led to an increasing interest in recovery and recycling, in line with the expressed EU policy in the Europe 2020 strategy to reduce Europe's efficiency and in the EU strategy for sustainable development. The Carrara marble basin is one of the most emblematic cases in the Italian stone industry, and it includes about one hundred quarries of colored and white marble, exploited from Roman times. Even if the new technologies have improved efficiency in quarrying and reduced the production of waste, around 50% of the extracted marbles in the Carrara basin still result in waste. Modern cutting technologies generate greater amount of finer materials and sawing residue, varying in size from sand to silt. Due to this very fine particle, it’s easy to see how this characteristic can cause problems with the stability of landfills, with consequent difficulties for their management. The aim of this research is to provide a comparison between different characteristics of marble fine waste in Carrara, both sludges deriving from quarry-cutting and stone processing, to demonstrate the feasibility of their recovery and utilization in different industrial application (i.e., mineral fillers, high value-CaCO3 products, building sector). The results obtained from analysis are promising and could lead to a possible reuse of the materials, in line with the circular economy approach. The reuse of marble waste can bring the double benefit of giving a new value to this by-product and, at the same time, partially eliminate the environmental problem caused by it. The combination of all these insights could lead to sustainable mining of the ornamental stones industry.

How to cite: Tazzini, A., Gambino, F., Casale, M., and Dino, G. A.: Circular economy in extractive industry: challenge and chance to recover fine particles produced in marble quarries exploitation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-652, https://doi.org/10.5194/egusphere-egu24-652, 2024.

08:45–08:55
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EGU24-948
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ECS
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Highlight
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Virtual presentation
Marco Casale, Xinyuan Zhao, Faten Khelifi, Alessandro Cavallo, Elio Padoan, Ke Yang, and Giovanna Antonella Dino

Rare Earth Elements (REE) are considered to be highly "critical" by the European Commission because the concentration of global supply and their use in a wide range of emerging technologies (e.g. smart phones, electric cars and wind turbines) and this at a time of increasing geopolitical tensions. According to the European Commission’s assessment, the demand for rare earth elements is expected to increase more than fivefold by 2030. Today, Europe is dependent on imports of these minerals, where China completely dominates the market, a factor which increases the vulnerability of European industry. Alternative sources of REE in Europe, such as recovery of quarrying and processing waste, are being considered.

This research, part of an italian project NODES, wich has received funding (PNRR) from the EU, about circular economy and recovery of mineral waste, focuses on the possibility to recover REE from extractive waste. The investigated area cover Piedmont Region in northern Italy. Waste materials from gneisses and granites (ranging from blocks up to residual sludge) used as dimension stones were characterized for volume, chemistry, mineralogy, and texture.

Based on the first analyses carried out, the most interesting contexts are those related to gneisses in Luserna Stone and Verbano Cusio Ossola quarrying area and to quartzites of Monte Bracco quarrying area.

Thanks to a proper treatment activity (grinding, screening and magnetic separation), these materials, present in past extractive waste facilities and in extractive waste coming from exploitation and working activities, could be used to recovery of REE. After the first phase, connected to “waste” characterisation, the following activities will be linked to processing of the richest samples to exploit (at Laboratory level) REE, and to economic issues.

An additional step will include leaching extraction tests (always at laboratory scale) to identify the best and most sustainable technique to extract and separate REE from the sampled extractive waste.

 

Key words: Rare Earth Elements, Critical Raw Materials, Supply-chain, extractive waste, mining waste, leaching, magnetic separation.

How to cite: Casale, M., Zhao, X., Khelifi, F., Cavallo, A., Padoan, E., Yang, K., and Dino, G. A.: Alternative ways to supply Rare Earth Elements: extractive waste recovery., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-948, https://doi.org/10.5194/egusphere-egu24-948, 2024.

08:55–09:05
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EGU24-7191
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ECS
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Virtual presentation
Shivam Sharma, Debabrata Das, Prakash Tiwari, and Ramkrishna Mondal

Rare earth elements and yttrium have attracted considerable attention in recent decade due to their crucial roles in modern technology, particularly in the production of electronics, magnets, and batteries. These elements are of particular importance for developed and developing countries, as they play a significant role in clean energy as well as their growth and development. The concentration, distribution, and modes of occurrence of rare earth elements and yttrium in coal from the Oligocene formation in the Makum coalfield were investigated in this study. The study found that the coal samples from the Makum coalfield have a low ash and high sulfur content. Furthermore, the study revealed that the total concentration of rare earth elements and yttrium in the coal samples ranged from 1.48 to 77.61 ppm, with an average of 27.49 ppm. Based on the analysis of the coal samples. Average concentration of rare earth elements and yttrium in the Makum coalfield, as observed in this study, is lower than the concentration found in world average coals. it was observed that the 60ft coal seam had a higher average LREE/HREE ratio compared to the 20ft and 8ft coal seams. This indicates variations in the distribution patterns of rare earth elements and yttrium within the different coal seams. Coals from this region show a positive europium anomaly and have a weak negative cerium anomaly, indicating a significant marine influence during their formation. The sequential leaching used in this study provided valuable insights into the modes of occurrence of rare earth elements and yttrium in the coal samples from the Makum coalfield. Having a comprehensive understanding of the proportions of rare earth elements and yttrium in different forms, such as organic, silicate-aluminate, acid soluble, ion-exchangeable, and water soluble, is crucial for the development of effective methods and technologies for the extraction of these critical elements from coal.

How to cite: Sharma, S., Das, D., Tiwari, P., and Mondal, R.: Rare earth elements and yttrium in Oligocene coals of Makum coalfield, Assam (North-east India), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7191, https://doi.org/10.5194/egusphere-egu24-7191, 2024.

09:05–09:15
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EGU24-21695
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ECS
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Highlight
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On-site presentation
Junaid Ghani, Katerina Rodiouchkina, Ilia Rodushkin, Enrico Dinelli, Valerio Funari, Thomas Aiglsperger, Lena Alakangas, and Emma Engström

Municipal Solid Waste Incineration (MSWI) plants are of great concern, generating solid by-products, namely Fly Ash (FA) and Bottom Ash (BA). These MSWI residues have received significant attention for environmental concerns and the recovery of valuable elements, minerals, and secondary raw materials. The potential recovery of elements in MSW are crucial for circular economy and environmental sustainability (Han et al, 2021; Funari et al, 2016). Therefore, available types of fly ashes samples, i.e., lime- and soda-doped fly ash from bag filters following electrostatic precipitation, and quenched BA samples were sampled during pre- (2013, 2020) and post-pandemic period (2021, 2022) from two grate-furnace MSWI plants, located in Ferrara (FE) and Forlì (FC) cities in Italy. The sample preparation and elemental analysis were performed at ALS Scandinavia laboratory as a part of an international research collaboration between University of Bologna, Luleå University of Technology, and ALS Scandinavia. In this study, we aimed to determine and compare the elemental composition in MSWI samples by Inductively Coupled Plasma-Sector Field Mass Spectrometry (ICP-SFMS) to assess metal abundance by enrichment factor and elemental flows using substance flow analysis and MSWI systems’ mass balance (Brunner and Rechemberg, 2004). Our results showed that recovery of valuable elements (Al, Fe, Si, Zn, and Cu) was high after strong digestion method for all the FA and BA samples. Overall, little variation in elemental composition of FA and BA in both selected periods (pre-pandemic vs post-pandemic) suggests a similar input flow of urban waste. Enrichment factors (EF) show enrichment of Zn, Cu, Al, Fe, Mg, Ca, Na, K, and potentially toxic elements like Pb, Cd in both FA and BA. The chondrite normalized REE patterns of FA and BA are relatively similar suggesting that the BA and FA feeding material are mostly geogenic materials, with possible anthropogenic fluctuation for Ce, Tb, and Yb. The upper continental crust (UCC) normalization patterns were consistent for most elements. In contrast, Ba, K, P, and La patterns vary, likely showing an anthropogenic signal. Mass balance assessment showed that the waste streams can host from low to high concentration of strategic elements as an alternative source of value in the circular economy.

 

References

  • Funari, V., Bokhari, S.N.H., Vigliotti, L., Meisel, T. and Braga, R., 2016. The rare earth elements in municipal solid waste incinerators ash and promising tools for their prospecting. Journal of Hazardous materials, 301, pp.471-479.
  • Han, S., Ju, T., Meng, Y., Du, Y., Xiang, H., Aihemaiti, A. and Jiang, J., 2021. Evaluation of various microwave-assisted acid digestion procedures for the determination of major and heavy metal elements in municipal solid waste incineration fly ash. Journal of Cleaner Production, 321, p.128922.
  • Brunner, P.H., Rechberger, H., 2004. Methodology of MFA. In: Practical Handbook of Material Flow Analysis. Lewis Publishers, Boca Raton London New York Washington, D.C., pp. 34–166, ISBN: 1-5667-0604-1.

How to cite: Ghani, J., Rodiouchkina, K., Rodushkin, I., Dinelli, E., Funari, V., Aiglsperger, T., Alakangas, L., and Engström, E.: Recovery of Metals from Municipal Solid Waste Incineration Plants Wastes: A Comparative Case Study of Pre- and Post-Pandemic Periods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21695, https://doi.org/10.5194/egusphere-egu24-21695, 2024.

09:15–09:25
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EGU24-19639
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Highlight
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On-site presentation
Axel D. Renno, MD Naziat Hossain, Anna Magdalena Baecke, Abrar Kabir, and Stefan Dirlich

Within the FINEST project (https://finest-project.de/) we tackle the use and management of finest particulate anthropogenic material flows in a sustainable circular economy. Subproject 3 "FINEST Disperse Metals" has set itself the goal of safely mixing various fine and ultra-fine-grained material flows that accumulate as waste during various industrial processes and extracting metallic raw materials from them in a subsequent multi-stage pyrometallurgical process, as well as generating a safe slag that can be disposed of without monitoring.

The idea of mixing different fine-grained waste streams arose from the experience that the search for economically and ecologically sustainable forms of recycling for the individual types of waste often failed despite promising approaches. This is usually due to individual parameters of the chemical or phase composition. The mixing we are aiming for allows us to select the technological parameters much more freely and to react to the rapid changes that are typical of waste streams.

We will implement this concept using three different material streams:

  • So-called shredder fines from plastics, car and WEEE recycling
  • Metallurgical fly ash from non-ferrous metallurgy
  • Quarry dust and dust from concrete recycling.

 

The experimental work is preceded by a comprehensive characterization of the material flows in terms of chemical and phase composition, general physical parameters such as particle size distribution, particle shapes and flowability as well as any potential hazards. Based on this, both the mixing behavior and the pyrometallurgical parameters are modeled.

We use quarry dust for two main purposes. Their main contribution is to act as slag formers in the pyrometallurgical processing of the mixtures in the plasma furnace. This should be combined with the lowest possible liquidus temperatures and viscosities of the slag system. We are currently using four different quarry dusts from active quarries in the Free State of Saxony for our investigations (1 granite, 2 granodiorites and 1 amphibolite) as well as material from the concrete recycling of an extensive demolition project in Dresden.

Optimized mixing ratios between the individual quarry dusts and various metallurgical flue dusts were determined as part of the modeling using FactSageTM.  The behavior during mixing of the material flows was initially investigated theoretically using model materials. The mixing steps were visualized using X-ray computed tomography.

How to cite: Renno, A. D., Hossain, M. N., Baecke, A. M., Kabir, A., and Dirlich, S.: Quarry dust an essential component in the pyrometallurgical recovery of valuable materials from mixed fine-grained waste, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19639, https://doi.org/10.5194/egusphere-egu24-19639, 2024.

09:25–09:35
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EGU24-17463
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ECS
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On-site presentation
Stefanie Hetz and Axel Schippers

Laterite ore deposits in Brazil and other tropical countries harbor large amounts of nickel and cobalt resources, along with other critical raw materials. The conventional methods of recovering nickel and cobalt, such as pyrometallurgy or high-pressure acid leaching, entail high energy, reagent costs, and expensive equipment. To address this, the German-Brazilian project BioProLat aims to develop an integrated, low-energy, and environmentally friendly biohydrometallurgical process for metal recovery from Brazilian laterite ores.

The process involves leveraging acidophilic bacteria that use sulfur as an electron donor, coupling sulfur oxidation to the reduction of ferric iron, ultimately converting insoluble metal compounds into water-soluble forms. This generates sulfuric acid, creating the necessary acidic conditions to keep iron and other metals soluble. Laboratory-scale bioreactor experiments optimized parameters like pH, temperature, and a suitable bacterial consortium for bioleaching nickel and cobalt. Results from aerobic bioleaching of laterite with a consortium of Acidithiobacillus thiooxidans strains showed an extraction of 85% for both cobalt and nickel. Mineralogical and geochemical analyses were conducted to identify mineral phases, which are attacked by bioleaching, and estimate the portions of cobalt and nickel released by bioleaching of different mineral phases. The goal is to scale up the optimized process, converting untapped ores and limonite stockpiles into valuable resources and unlocking new raw material reserves by enhancing metal recovery from existing mines.

How to cite: Hetz, S. and Schippers, A.: Stirred-tank reactor bioleaching of nickel and cobalt from Brazilian laterite ores, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17463, https://doi.org/10.5194/egusphere-egu24-17463, 2024.

09:35–09:45
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EGU24-16673
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ECS
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On-site presentation
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Francesco Falabella, Antonio Pepe, Krištof Oštir, and Fabiana Calò

This work addresses the preliminary achievements of the Horizon Europe European project S34I1 (Secure and Sustainable Supply of Raw Materials for EU Industry) (https://s34i.eu) that aims to increase the autonomy of Europe over raw materials resources through research and development of new data-driven methods devoted to the analysis of Earth observation data.

Among the different activities of the project, one of the major contributions is related to the systematic monitoring of mining site instabilities by developing and applying advanced multi- temporal interferometric SAR (InSAR) techniques for the generation of long-term deformation time series. To this purpose, an InSAR multi-grid technique for efficient processing of sequences of differential SAR interferograms (particularly, phase unwrapping operations) has been carried out directly at the native high-resolution spatial grid without any model or assumption on deformation.

Experiments were carried out at the Gummern, Austria, extraction site by processing two sets of ascending and descending SAR datasets collected by the EU Copernicus Sentinel-1A/B sensors from October 2014 to March 2023. The line-of-sight (LOS)-projected ground displacement time series were generated by inverting the unwrapped single-look interferograms using the Small BAseline Subset (SBAS) algorithm. Consequently, non-linear and seasonal patterns that could indicate a sudden failure of the surface can be identified with millimetre precision. A post-operation step was also performed over the group of georeferenced common targets as seen from complementary geometries (i.e., ascending and descending orbits) to compute from LOS-projected ground deformations the long-term 2-D (up-down, east-west) ground displacement time series. To this aim, conventional and new combination methods are applied by assuming the north-south displacements do not significantly contribute to the observed LOS measurements.

1This study is funded by the European Union under grant agreement no. 101091616, project S34I – SECURE AND SUSTAINABLE SUPPLY OF RAW MATERIALS FOR EU INDUSTRY, coordinated by Ana C. Teodoro.

How to cite: Falabella, F., Pepe, A., Oštir, K., and Calò, F.: Use of Interferometric Synthetic Aperture Radar Techniques as a remote tool for Mineral Extraction Sites Monitoring , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16673, https://doi.org/10.5194/egusphere-egu24-16673, 2024.

09:45–09:55
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EGU24-7319
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ECS
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On-site presentation
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Sophie Graul, Vincent Monchal, Rémi Rateau, Lauri Joosu, Marko Moilanen, Mawo Ndiaye, and Rutt Hints

The importance of rare earth elements (REEs) in high-tech industries and the growing demand for raw materials have spurred interest in exploring unconventional deposits. Sedimentary phosphorite deposits are among the most prospective, with REE extraction as a P by-product. However, these ores are highly diverse regarding ΣREE content, distribution, and nature of phosphatic materials. This study focuses on the Estonian phosphorites of the Baltic paleobasin, which constitute one of Europe's largest phosphate rock reserves and are characterised by phosphatic shell fragments deposited in nearshore settings.

Geochemical investigations were conducted on carbonate-cemented phosphorites from Toolse and Aseri deposits. The determination of REE distribution and uptake mechanisms within apatites and carbonates was addressed by LA-ICP-MS in situ imaging technique developed by Drost et al. (2018), which allows identification and discrimination of mineral phases by integrating semiquantitative compositional data through the stepwise elemental distribution. Diagenetic enrichment stages were assessed using the following pathfinder elements as pooling channels: Sr and U.

Shelly apatites have homogenous REE-distribution patterns, MREE-enriched up to 15-fold compared to the PAAS, with positive Y and Ce anomalies indicative of an early digenetic overprint traceable by the Sr distribution. The average REE content in studied apatite is 2149ppm. However, the extent of diagenetic overprint and enrichment varies locally. In Toolse, shells show lesser recrystallised textures, and the Sr- and U-depleted stages allow the tracing of pristine signals prior to deposition. In Aseri, U-sorting reveals a second, alteration-driven enrichment in which fragment edges present a ΣREE up to 7020ppm. This alteration stage is less pronounced in Toolse, where REE content reaches only 4150ppm. The distinction between Sr and U-driven enrichment is less evident due to the lower input of hydrogenic or lithogenic REE carriers. The carbonates from both localities were found to be REE depleted compared to PAAS.

Based on these observations, the compositions of the apatite species could be distinguished and modelled to characterise the deposit. The diagenetic enrichment of REE was mainly driven by the upwelling of nutrient-rich waters, Fe and Mn-(oxyhydr)oxide reductive desorption, and secondary phosphatisation and homogenisation of shells. Fluctuations of redox gradients and Fe-Mn cycles led to slight local REE variability. Developing euxinic conditions and lithogenic input endorsed a later alteration-driven uptake, resulting in highly REE-rich edges. Despite differences in enrichment level, the two deposits' REE distribution patterns are similar. Main REEs are Ce (33%), Y (21%), La (12%), Nd (16%) and Dy (3%), and are considered among the most critical elements. On average, U concentrations are 92ppm in Aseri and 31ppm in Toolse, and toxic elements (Cd, Zn, Th) are found in trace amounts.

The study introduces a combined technique based on LA-ICP-MS and empirical distribution function data analyses as a powerful, accurate, cost-effective tool for determining REE distributions. It allows visualisation at different scales, representative measurements and a first approach to semi-quantifying elements. The method could provide insights into factors that control genesis in low-grade sedimentary ores and determine their potential valorisation routes.

How to cite: Graul, S., Monchal, V., Rateau, R., Joosu, L., Moilanen, M., Ndiaye, M., and Hints, R.: LA-ICP-MS imaging technique application on Estonian sedimentary phosphorites: Revealing REE enrichment stages and advanced ore characterisation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7319, https://doi.org/10.5194/egusphere-egu24-7319, 2024.

09:55–10:10

Posters on site: Mon, 15 Apr, 16:15–18:00 | Hall X1

Display time: Mon, 15 Apr 14:00–Mon, 15 Apr 18:00
Chairpersons: Giovanna Antonella Dino, Antonello Aquilano, Stefan Dirlich
X1.125
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EGU24-1809
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ECS
Shuangliang Liu, Mingshi Wang, Zhaoyang Gao, Xuan Liu, Hong-Rui Fan, Alan Butcher, Yann Lahaye, Radoslaw Michallik, Ester Jolis, and Sari Lukkari

Scandium (Sc) is famous as a rare-scattered element in nature but can be anomalously enriched by the carbonatite system, especially in the Bayan Obo deposit (~0.14 Mt). However, the Sc distribution of Bayan Obo deposit is rarely revealed, which hinders resource utilization and the understanding of Sc mineralization. Thus, we comprehensively analyze the occurrence and distribution characteristics of Sc resources of Bayan Obo deposit, from deposit scale to mineral scale, based on 236 samples and 13 representatives. In the deposit scale, the Sc contents are 301-2 ppm (banded/massive type ores), 273-91 ppm (vein-type ores), 77-17 ppm (ore-hosting dolomite), and 281-1 ppm (slate/schist) for different rock types, respectively. Among them, the high-Sc rocks usually occur in the vicinity of the contact zone between the H9 slate/schist and the ore-hosting dolomite, which represents the most intently fenitization area in Bayan Obo. In the rock scale, Sc is heterogeneously scattered in rock with a small volume ratio (less than 0.1‰) of extremely high-Sc domains (Sc contents >0.3 wt. %). In contrast, Sc resources are more commonly found in aegirine and Na-amphibole, ranging from hundreds to thousands of ppm, sometimes reaching several weight percent, of banded/massive type ores and vein-type ores, and in biotite and titanite of altered slate/schist, typically in dozens of ppm. Notably, in the mineral scale, three types of individual Sc minerals are first distinguished in the Bayan Obo carbonatite deposit, that is thortveitite, aegirine-jervisite solid solution, and bazzite. Their metasomatism texture and mineral associations record two Sc migration and precipitation events in this deposit. These new reports reveal that the hydrothermal process is the main controlling factor of Sc resources in the Bayan Obo carbonatite system, and provide a scientific basis for the rational and effective utilization of Sc resources in this deposit.

How to cite: Liu, S., Wang, M., Gao, Z., Liu, X., Fan, H.-R., Butcher, A., Lahaye, Y., Michallik, R., Jolis, E., and Lukkari, S.: The occurrence and distribution of Scandium resources in the world-class Bayan Obo REE-Nb-Fe deposit, China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1809, https://doi.org/10.5194/egusphere-egu24-1809, 2024.

X1.126
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EGU24-6141
Susanna Mancini, Francesca Gambino, Antonio Tazzini, and Giovanna Antonella Dino

The present research focuses on one of the most complex and challenging applications of 'sustainable' mortar use in restoration. The study stems from the context of the PNRR NODES project – Spoke 2, coordinated by the University of Turin and promotes sustainable development and technologies for a “greener” future.

In modern construction, the use of mortars demands a finished product that is suitable for its use, with good aesthetic properties and durability over time. These characteristics are even more crucial in a restoration project, where compatibility with the old material comes into play. The sustainability of 'raw' materials, in this case secondary raw materials, is an issue that characterises the current historical moment. In this context, the characterisation of ancient mortars plays a fundamental role in establishing correlations with their sources and for the creation of new formulations.

The sustainability of 'alternative' mortars refers to the valorisation of local products, the use of waste materials and fully recyclable compounds, and reduced impact on human health and the environment. One of the potential compounds to use for mortar production can be collected from extractive waste associated to marble and limestone exploitation. Indeed, lime is alkaline and non-toxic, well-known as antiseptic and disinfectant. In addition, due to the low burning temperature and partial reabsorption of carbon dioxide during setting, lime, especially quicklime, is characterised by lower permanent CO2 emissions.

In this study different protocols are carried out, compared, and analysed in detail, with the aim of systematising 'alternative' restoration mortar formulations. These are based on the use of 'geomaterials', like waste from mining industry and construction and demolition. In particular, the lime-based binder is obtained from the calcination of white marble waste (quarry sludge, sawdust, etc.) from two different quarries located in Tuscany and Val d'Aosta. The aggregate used for the skeleton of the mortars can be obtained from quarry waste in Piedmont and Val d'Aosta (e.g. gneisses, granites, marbles, limestone, etc.) and/or concrete selected from treatment plants that recycle construction and demolition waste.

Finally, each formulation is evaluated regarding performance, compatibility with historic mortars and potential contribution to the circular economy.

The results of this research activity are an example of a multidisciplinary approach to the conservation and sustainable management of cultural heritage sites, where issues of scientific research, art, green building and circular economy are intertwined.

How to cite: Mancini, S., Gambino, F., Tazzini, A., and Dino, G. A.: Sustainable restoration mortars in a circular economy perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6141, https://doi.org/10.5194/egusphere-egu24-6141, 2024.

X1.127
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EGU24-6287
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ECS
Discovering the Critical and Strategic Raw Materials potential of historical mining dumps of Sardinia 
(withdrawn)
Lorenzo Sedda, Antonio Attardi, Giovanni De Giudici, and Stefano Naitza
X1.128
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EGU24-8434
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ECS
Antonello Aquilano, Elena Marrocchino, and Carmela Vaccaro

The Sardinia region has a longstanding tradition in ornamental granite extraction, reaching its production peak in the 1990s when it became Italy's leading granite producer, accounting for 90% of the national production [1]. However, the industry faced a decline starting from the mid-2000s due to the entry of other competitors into the global market and due to significant infrastructure issues on the island [1]. The 2008 financial crisis further reduced global granite demand and in the subsequent years, compounded by the events of the COVID-19 pandemic, prolonged the crisis in the sector. In Italy, granite production plummeted from over 2 million metric tons in 2011 to just under 200,000 metric tons in 2022 [2].
Granite extraction has a striking impact on the Sardinian landscape, with landfills of granite blocks, visible from kilometers away, contributing to significant landscape degradation. These, in addition, affect plans to develop the unique archaeological sites of the Domus de Janas and contribute to soil depletion. 
The European Critical Raw Materials Act to future supply chains is crucial for Europe's green and digital transition, in line with the European Green Deal that identified recycling as part of the supply solution. In this context, recognizing potential opportunities for recycling these waste materials could aid in advancing the objectives of the European Union, enhance the aesthetic quality of the Sardinian landscape, and contribute to revitalize the granite extraction industry in Sardinia.
This study focuses on the circular economy in a granite quarry located in the municipality of Buddusò (province of Sassari, Sardinia). Active for about 40 years, this quarry has accumulated significant amounts of granite waste from which feldspar, quartz and rare earth elements can be extracted. This research presents the results of geochemical, petrographic, and mineralogical analyses conducted on granite waste samples from the quarry under study. In addition, potential recycling solutions for this material in the context of Critical Raw Material supply are discussed.

References:

[1] Careddu, N.; Siotto, G.; Marras, G. The Crisis of Granite and the Success of Marble: Errors and Market Strategies. The Sardinian Case. Resources Policy 2017, 52, 273–276. https://doi.org/10.1016/j.resourpol.2017.03.010.
[2] Istituto Nazionale di Statistica - Istat. Production in Value and Quantity per Single Product - Granite and Similar Rocks, Rough, without Shape. Accessed 18/12/2023. https://esploradati.istat.it/databrowser/#/it/dw/categories/IT1,Z0600IND,1.0/IND_PRODUCTION/DCSP_PRODCOM/IT1,115_168_DF_DCSP_PRODCOM_2,1.0

How to cite: Aquilano, A., Marrocchino, E., and Vaccaro, C.: Granite waste produced in quarries exploitation in northern Sardinia (Italy): recycling chances within the context of Critical Raw Material supply, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8434, https://doi.org/10.5194/egusphere-egu24-8434, 2024.

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EGU24-8511
Carmela Vaccaro, Antonello Aquilano, and Elena Marrocchino

SEM-EDS and polarized optical microscopy analysis of granite blocks taken from decorative rocks quarry waste landfills in Sardinia were used in mining prospecting to evaluate potential unconventional sources of critical raw materials (CRMs). Achieving the goals outlined in the European Green Deal regarding the green and digital transition may face significant challenges due to the substantial increase in demand for CRMs in the near future so access to CRMs is a strategic security issue for the European Union.

Because of the similar chemical properties that characterize Rare Earth group elements among themselves, there are few effectively exploitable deposits in the world. Predominantly in carbonatite complexes and pegmatitic granitoid bodies, the subtle variations in the properties of RE (Rare Earth) group elements allow significant fractionation and economically exploitable enrichment of small intrusive bodies and/or intrusive veins consisting of one or more REE minerals, such as allanite, REE oxides, apatites, and carbonates.

Sardinia's ornamental granite quarries have in the past generated high concentrations of unmarketable waste (mostly pegmatite bodies and veins with REE-enriched late-magmatic and deuteric mineralogical phases). The huge amount of these waste accumulations has resulted in high land consumption and landscape distortions, but with the increased REE demand they now represent an important resource, as they can contribute to the implementation of the EU Critical Raw Materials Act.

This study reports the results of SEM-EDS investigations combined with polarized optical microscope observations conducted on thin sections of granite obtained from waste samples from the numerous leucogranite quarries of Buddusò (Northern Sardinia, Italy). These granites are composed primarily of quartz, plagioclase, K-feldspar, and biotite, with accessory minerals including zircon, epidote, titanite, ilmenite, apatite, and xenotime. Feldspars have recently been included in the list of Critical Raw Materials[2]; therefore, the identification of solutions for their exploitation (which represent a significant portion of the rocks investigated) could provide a strong contribution to the needs of the European Union. Epidotes often appear in these rocks as allanite enriched in light rare earth elements.

In this context, it could be very interesting to evaluate the possibility of applying physical mineral separation methodologies to obtain, on the one hand, mineral concentrates containing Rare Earth Elements for the extractive metallurgy industry. On the other hand, feldspars have recently been included in the list of Critical Raw Materials [1]; therefore, identifying solutions for their exploitation (which represent a significant portion of the investigated rocks) could provide a strong contribution to the needs of the European Union.

This study of the quartz and feldspar phases and REE concentrations in accessory minerals will be useful in optimizing the physical separation methodologies of minerals useful to obtain CRMs for industry and the ceramic and glass manufacturing sectors.

Reference:

[1] Grohol, M., C. Veeh, DG GROW, e European Commission. «Study on the Critical Raw Materials for the Europe - Final Report». Luxembourg: European Union, 2023.

How to cite: Vaccaro, C., Aquilano, A., and Marrocchino, E.: SEM-EDS and Polarized Optical Microscope Analysis of Granite Quarry Waste to Reveal Potential Unconventional Sources of Critical Raw Materials, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8511, https://doi.org/10.5194/egusphere-egu24-8511, 2024.

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EGU24-16645
Jakob K. Keiding, Nolwenn Coint, Benjamin Heredia, Nynke Keulen, Yann Lahaye, and Xuan Liu

Raw material supply chains are intricate and complex systems that often suffer from a lack of transparency. To enhance sustainability in mineral supply, there is an urgent need to rectify this transparency deficit. Traceability, which involves tracking a product through different stages of production, transformation, and commercialization, from its origin to its end-of-life, including potential recycling, could be a crucial facilitator for increased transparency.

Nd magnets (also known as NdFeB magnet) are the strongest permanent magnet type known and serve as critical components in green technologies like windmill turbines and electric motors for vehicles. While Nd magnets offer numerous advantages, their production involves the use of rare earth elements (REE), critical raw materials that lack supply chain transparency, standards, and certification schemes regarding environmental and social impacts, and governance. The objective of this study is to investigate whether there are distinct chemical characteristics associated with Nd magnets and to determine the feasibility of establishing a correlation between a magnet and unidentified information, potentially linking it to a plausible source.

Nd magnets have been systematically collected for the purpose of tracing their material origins. Two distinct categories of Nd magnets were assessed for this investigation. The first category comprises novel magnets with documented production years (ranging from 1999 to 2023) and varying grades marked by different Nd contents. The second category consists of magnet scraps lacking specific information. Our study employed a comprehensive approach, incorporating automated quantitative mineralogy (AQM), Scanning Electron Microscope spectroscopy element mapping (SEM-EDS) to examine microtextures and major element content, and LA-ICP-MS analyses for trace elements and Nd isotopes.

Analyzing these magnets revealed noticeable compositional distinctions among samples, both in terms of manufacturing sources and production years. Four distinct groups of trace elements were identified in the novel magnets, aiding in the differentiation of various production year groups. These groups include Ti, Cr, Se, La, Cr, Nd, Gd, Yb (Group 1), B, Eu, Tb (Group 2), Al, As, Ge, Pr, Sm, Dy, Tm (Group 3), and Mn, Ho (Group 4). Nd isotope analyses indicated a broad present-day epsilon Nd values, ranging from -30 to -7, with some degree of inter-sample overlaps. This extensive range appears to surpass the typical coverage of REE deposits. Higher values suggest the potential incorporation of REEs from South China ion-absorption deposits, while lower values hint at the involvement of REEs from Olympic Dam (Australia) and/or Mountain Pass (US).

These preliminary findings contribute with valuable insights into the diverse origins and compositions of Nd magnets, suggesting that geochemical fingerprinting could emerge as a pivotal traceability tool for assessing the origin of Nd magnets in the future.

How to cite: Keiding, J. K., Coint, N., Heredia, B., Keulen, N., Lahaye, Y., and Liu, X.: Geochemical tracing of Nd magnets – a possible future tool to improve sustainable sourcing of critical raw materials?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16645, https://doi.org/10.5194/egusphere-egu24-16645, 2024.

Posters virtual: Mon, 15 Apr, 14:00–15:45 | vHall X1

Display time: Mon, 15 Apr 08:30–Mon, 15 Apr 18:00
Chairpersons: Antonello Aquilano, Giovanna Antonella Dino, Stefan Dirlich
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EGU24-6851
Ouafi Ameur-Zaimeche, Rabah Kechiched, Paola Mameli, Ernesto Mesto, Giovanni Mongelli, Abdelhamid Oulad mansour, and Emanuela Schingaro

This research explores the major element control on the distribution of critical metals (CM) in red muds (RM), the residues of the Bayer process developed on bauxite ore, sampled at the Porto Vesme disposal site, Sardinia, Italy. RM represent an environmental challenge due to their high alkalinity and storage issues. The relationships between major elements and CM were assessed by Compositional Data Analysis (CoDa).

X-ray powder diffraction (XRPD) revealed predominant minerals including hematite, gibbsite, boehmite, anatase, cancrinite, sodalite, and quartz, consistent with previous studies on RM from the same site (Castaldi et al., 2008; Mombelli et al., 2019). Inductively Coupled Plasma Mass Spectrometry (ICP-MS) assessment reported the major oxides composition (wt %): SiO2 (11.9 – 22.6), Al2O3 (17.4 – 24.9), Fe2O3 (22.2 – 30.3), MgO (0.7 – 4.7), CaO (2.6 – 5.9), Na2O (3.5 – 11.5), K2O (0.2 – 0.7). Iron content averaged at 25.8 wt%, underscoring i considerable presence of iron in bauxite residues, while alumina averaged at 20.75 wt% is consistent with the large amount of Al-hydroxides detected by XRPD. Among CM, specifically the LREE, the Ce abundance (93 – 258 ppm) is a notable feature.

CoDa involved Principal Component Analysis after a transformation of raw data into centred log ratio. The PC1 and PC2 association revealed significant influence from TiO2 and Na2O on critical metals such as HREE, LREE, Sc, and Co. Noteworthy is the Bayer process involving high-temperature pressure leaching of bauxite ores with sodium hydroxide solution for the Al recovery, leaving TiO2 in the resulting residue. Other CM, such as V and Ga, are predominantly controlled by MgO.

This preliminary study suggests that RM could be a promising geo-material for a strategic CM recovery and efficiently reusing the secondary byproduct, providing a sustainable and environmentally friendly alternative to its mere disposal (Liu and Naidu, 2014).

How to cite: Ameur-Zaimeche, O., Kechiched, R., Mameli, P., Mesto, E., Mongelli, G., Oulad mansour, A., and Schingaro, E.: Critical metals distribution in Bauxite Residues: a Compositional Data Analysis approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6851, https://doi.org/10.5194/egusphere-egu24-6851, 2024.