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Major benefits and constraints related to mineral extraction within the EU have been identified on the examples of selected critical raw materials’ deposits. Analyzed case studies include the following ore deposits: Myszków Mo-W-Cu (Poland), Juomasuo Au-Co (Finland), S. Pedro das Águias W-Sn (Portugal), Penouta Nb-Ta-Sn (Spain), Norra Kärr REEs (Sweden) and Trælen graphite (Norway). They represent different stages of development, from the early/grassroot exploration stage, through advanced exploration and active mining, up to reopening of abandoned mines, and refer to different problems and constraints related to the possibility of exploitation commencement. The multi-criteria analysis of the cases has included geological and economic factors as well as environmental, land use, social acceptance and infrastructure factors. These factors, in terms of cost and benefit analysis, have been considered at three levels: local, country and EU levels. The analyzed cases indicated the major obstacles that occur in different stages of deposit development and need to be overcome in order to enable a new deposit exploitation commencement. These are environmental (Juomasuo and Myszków), spatial (Juomasuo) as well as social constraints (Norra Kärr, Juomasuo). In the analyzed cases, the most important constraints related to future deposit extraction occur primarily at a local level, while some important benefits are identified mainly at the country and the EU levels. These major benefits are related to securing long-term supplies for the national industries and strategically important EU industry sectors.

Based on research carried out at 67 tailings dams in Spain: (1) tailings dams contain alternating sedimentary layers with contractive and dilative geomechanical behaviours; (2) tailings saturate quickly but drain more than 10 times slower due to the high-suction capacity of the porous sediments (2–300 MPa); and (3) over the long-term, a stationary flow regime is attained within a tailings basin. Four temporal and spatial conditions must all be present for a tailing dams flow failure to occur: (1) the tailings must experience contractive behaviour; (2) the tailings must be fully saturated; (3) the effective stress due to static or dynamic load must approach zero; and (4) the shear stress must exceed the tailings residual shear stress. Our results also indicate that the degree of saturation (S r ) is the most influential factor controlling dam stability. The pore-pressure coefficient controls geotechnical stability: when it exceeds 0.5 (S r  = 0.7), the safety factor decreases dramatically. Therefore, controlling the degree of tailings saturation is instrumental to preventing dam failures, and can be achieved using a double drainage system, one for the unconsolidated foundation materials and another for the overlying tailings.

This work describes a special case of pollution potential assessment applied to an abandoned sulfide tailings impoundment located in the Riotinto mining district (Huelva), near the Tinto River. Three overlapping levels of discharged tailings were recognized in the impoundment, from deeper to upper: pale yellow to white, red, and brownish-yellow. Mineralogical, physical, and chemical characteristics of tailings, water leachates, water, and sulfate efflorescent salts were analyzed. The total toxic element content and the leachate concentration were respectively used to calculate two indices that support potential toxicity assessment: the Index of Contamination (IC) and the Hazard Average Ratio (HAQ). According to the IC values, all tailings samples showed a high potential for contaminating soils and sediments, especially the intermediate tailings with up to As (8.6 g kg −1 ), Pb (14.8 g kg −1 ), and Cu (1 g kg −1 ). Deeper tailings leachate was extremely saline and acidic, with a very high concentration of sulfates and toxic elements, exceeding the values: 2600, 980, 30, and 17 mg L −1 for SO 4 , Fe, Al, and Cu, respectively. For this reason, these deeper tailings were linked to the saline and acid seepage, and also to the sulfate acid efflorescences formed at the dike toe. In conclusion, the studied abandoned tailings impoundment is related with a high likelihood of polluting the environment, represented by very high IC and HAQ values. However, when the Tinto River is considered the receiving water body, the severity of the potential contamination must be judged as very low.

This work explores the ability of the Spanish Geochemical Database to identify the existence of polluted stream sediments due to the presence of abandoned mine wastes. The mining district of Sierra de Cartagena-La Unión has been used as test area. A total of 18 abandoned tailings facilities were selected and samples were taken for analysis of the content in potential toxic elements. The results were contrasted with geochemical background values in order to identify which geochemical elements could entail anomalies potentially reflected in the Spanish Geochemical Database. For the study area, As, Cd, Pb, and Zn have been identified as potential toxic elements which can be used as geochemical indicators of sediment pollution processes originated in abandoned mine wastes. Furthermore, the correlation between Cd and Zn allows them to be considered as the best indicators of potential sediment contamination. The study of anomaly thresholds, through the analysis of accumulated frequencies of the contents of these elements in the sediments of the Spanish Geochemical Database, allows identifying sediments that may have been contaminated. A Mann-Whitney test contrasting the data of tailings, polluted sediments, and non-polluted sediments has been performed in order to verify differences among these types of samples. In addition, a geospatial analysis has demonstrated a very close relationship between contaminated sediments and the presence of mining wastes upstream. This methodology can be applied to any other mining region, to recognize the possible influence of pollution processes derived from the presence of abandoned mine wastes taking advantage of existing geochemical databases.

On 17 August, 1960 the biggest disaster by death toll in Spain, related with a tailings dam fault, took place in Reocin (Santander). The tailings dam \"La Luciana\" failed causing the death of eighteen people. After the fault, the mining company carried out several geotechnical tests in the remaining materials of the tailings dam. The results are available to be consulted in the Reocin Mines Documentary Collection, from which we have obtained mechanical Cone Penetration Test (CPT) data near the fault area as well as diverse maps of the dam pre-failure and post-failure. The processing of such data through current analysis techniques has revealed the relationship between the fault of the tailings dam and static liquefaction phenomena.

El 17 de agosto de 1960 se produjo en Reocín (Cantabria) el mayor desastre en pérdidas de vidas humanas acaecido en España en relación con la rotura de una presa de residuos mineros. El depósito de residuos mineros \"La Luciana\" sufrió un fallo que derivó en costosos daños materiales y provocó la muerte a dieciocho personas. Tras la rotura, la compañía minera realizó diversos ensayos geotécnicos sobre los materiales remanentes del depósito. Los resultados obtenidos pudieron ser consultados en el Fondo Documental Mina de Reocín, obteniéndose datos de Ensayos de Penetración Estática (CPT) mecánicos del entorno de la zona de rotura, así como diversa cartografía del depósito anterior y posterior a la catástrofe. A la luz de los conocimientos actuales y el tratamiento de estos datos mediante nuevas técnicas, ha podido evidenciar la relación de la rotura del depósito con fenómenos de licuefacción estática.

Se describe una metodología para la evaluación del impacto paisajístico residual de una explotación de carbón a cielo abierto en el Valle de Laciana (España) tras el cese de la actividad, aplicando un índice de impacto paisajístico que evalúa: la pérdida de calidad visual del paisaje por la actividad extractiva, y su incidencia visual en función de la capacidad de absorción visual del medio, el grado de restauración de los terrenos alterados y su visibilidad desde las zonas más frecuentadas por la población. El resultado final de la evaluación es un impacto sobre el paisaje severo y moderado dependiendo de las unidades paisajísticas afectadas. Este índice paisajístico constituye una herramienta que puede ser aplicada en los diseños de restauración, en los planes de vigilancia de las evaluaciones de impacto ambiental y en la recuperación de áreas degradas por la minería.

This work describes a methodology to evaluate the landscape residual impact of an opencast coal mine in Laciana Valley (Spain), applying a landscape impact index that evaluates: the loss of visual quality of the landscape due to the extractive activity and its visual influence, depending on the visual absorption capacity of the environment, the degree of restoration of the upset areas, and its visibility from the zones most frequented by the population. Final results of the evaluation show severe and moderate impacts on landscape depending on the landscape unit. The landscape impact index is shown as a useful tool that can be applied to restoration designs, environmental vigilance plans and recovery of areas degraded by mining activity.

El 17 de agosto de 1960 se produjo en Reocín (Cantabria) el may or desastre en pérdidas de vidas humanas acaecido en España en relación con la rotura de una presa de residuos mineros. El dep ósito de residuos mineros “La Luciana” sufrió un fallo que deri vó en costosos daños materiales y provoc ó la muerte a dieciocho perso nas. Tras la rotura, la compañía minera realizó diversos ensayo s geotécnicos sobre los materiales remanentes del depósito. Los r esultados obtenidos pudieron ser consultados en el Fondo Docume ntal Mina de Reocín, obteniéndose datos de Ensayos de Penetración Es tática (CPT) mecánicos del entorno de la zona de rotura, así co mo diversa cartografía del depósito anterior y posterior a la catá strofe. A la luz de los conocimientos actuales y el tratamiento de estos datos mediante nuevas técnicas, ha podido evidenciar la relación de l a rotura del depósito con fenómenos de licuefacción estática.

In large-scale regional models, used for the management of underground resources, it is quite common to find that relationships between the regional aquifer and small wetlands are not included. These models do not consider this connection because of the small amount of water involved, but they should consider the potential for significant ecological impacts if the groundwater resources in the ecosystems associated with these wetlands are mismanaged. The main objective of this work is to investigate the possibilities offered by MODFLOW LGR-V2 to represent (at small scale) the Santa Olalla pond, located in the Doñana Natural Park (South of Spain), and its relationship with the Almonte-Marismas regional aquifer. As a secondary objective, we propose to investigate the advantages and disadvantages that DRAIN, RIVER and LAKE MODFLOW packages offer within the MODFLOW LGR-V2 discretizations. The drain boundary condition with a coarse discretization implemented through ModelMuse allows the most adequate performance of the groundwater levels in the environment of the pond. However, when using lake boundary condition, the use of the MODFLOW LGR-V2 version is particularly useful. The present work also gives some guidelines to employ these packages with the MODFLOW graphical user’s interface, ModelMuse 4.2.