Biocorrosion of Carbon Steel under Controlled Laboratory Conditions

In the Iberian Pyritic Belt (SW Europe), Acid Mine Drainage (AMD) is the consequence of the interaction of physical-chemical and biological factors, where aerobic Fe and/or S oxidizing chemolithotrophic and anaerobic sulfate reducing bacteria play an essential role. As a result, the polluted waters are highly acidic (pH 2–3) and contain numerous dissolved or suspended metals, which gives them a powerful corrosive action on constructions related to mining activities with high economic losses. To verify the role of bacteria in the corrosion of carbon steel, a common material in buildings exposed to corrosion in acidic waters, several experiments have been carried out under controlled conditions using carbon steel bars and acidic water containing bacteria consortia from an AMD river of the Iberian Pyritic Belt. In all the experiments carried out, a remarkable oxidation of supplemented iron was observed in the presence of bacteria. Using carbon steel as the sole iron source, we observed a slight corrosion of the bars, but when culture media was supplemented with elemental sulfur, steel bars was severely damaged. Since the bacteria inoculum come from the surface water, well oxygenated, nutrient-poor river, the obtained results are discussed based on facultative metabolism of acidophilic chemolithotrophic bacteria.This research was funded by Ministry of Science and Innovation (Spain), grant number PID2021-123130OBI0

Different evolution of tensile and compressive strength in concrete affected by acid mine drainage

Although not many studies have analysed the effects of acid mine drainage (AMD) on the durability of concrete, it is clear that such an aggressive environment affects the different mechanical parameters of this material. AMD is an environmental problem that affects the five continents and is especially widespread in the south western part of the Iberian Peninsula, in an area known as the Iberian Pyrite Belt. In this work, the effect of AMD on tensile and compressive strength of concrete has been evaluated, analysing the evolution of these two fundamental parameters on this structural material. For this purpose, a series of concrete samples were subjected to a controlled AMD environment in the laboratory, using water with pH 2.8 collected from the Tharsis Mine (SW Spain). The concrete samples were prepared in accordance with the parameters required by various international standards. The samples were subjected to the aggressive environment by AMD for two periods of time (3 and 6 months), after which they were subjected to non-destructive testing and destructive testing until breaking the samples by means of compression and tensile (indirect tensile test). In addition, Emission Scanning Electron Microscopy studies were performed on samples before AMD influence and on samples affected by AMD for six months. The obtained results using the ultrasonic equipment showed a decrease in concrete quality, an increase in porosity and permeability, the reduction of modulus of elasticity that reaches 8.5% after six months, as well as the appearance of microcracks. The destructive the tests showed that tensile strength is much more affected than the compressive strength: the tensile strength went from 4.31 MPa to 3.27 MPa (24%) after six months, while the compressive strength went from 48.22 MPa to 43.83 MPa (9%) in the same period of time. This different evolution means that the formulas used in international standards that relating compressive strength to tensile strength need to be modified by means of a correction factor.This work was supported by MCIN/AEI/10.13039/501100011033/ FEDER, UE (PID2021-123130OB-I00), the Regional Government of Andalucia (FEDER Operational Programme 2014-2020, UHU-202053) and the Huelva University (EPIT 2021, UHUPJ0001-624). Funding for open access charge: University of Huelva / CBU

Corrosion of Carbon Steel in Extreme Environments by Acid Mine Water: Experimental Study of the Process Using a Factorial Analysis Tool

Acid mine drainage (AMD) is a process resulting from mining activity, which has a potential degrading effect on metallic materials used in machinery and structural installations, mainly carbon steel composites. This work shows how steel is affected and degraded by AMD, as well as the physicochemical changes that occur in the solvent as a consequence of the metal corrosion process. For this purpose, thirty specimens were immersed in AMD for thirty weeks and were removed once per week, observing the changes that had occurred both in the metal and in the solvent to which it was exposed. The results show a material degradation with a loss of weight and alterations in the acid drainage with an increase in pH, total dissolved solids (TDS) and modifications in the rest of the solvent characteristics. The data from the measurements of the plates under study, together with the physicochemical data of the resulting reagent solution, were integrated into matrices for subsequent graphical–statistical processing using Statgraphics Centurion software, a powerful tool for exploratory data analysis, statistical summary, analysis of variance, statistical control, multivariate analysis, time series, etc., and which allows the different variables studied to be classified into categories or proximity ratiosThis work has been funded by an R&D&I project within the framework of the Andalusia FEDER Operational Programme 2014-202

Edition electronic support of didactic material for interactive self-learning

The creation of a new social-virtual space for human interrelations is necessary for new information and communication technologies. This new environment, which is being developed in the area of education, enables new processes of learning and transmission of knowledge through modern communication networks. All this invites us to support ourselves in the principles of hypertext education and autonomous learning together with the collective and cooperative. The aim is to reinforce learning through an interactive learning technique based on problems and selfevaluation. To achieve these objectives, it would be necessary to combine teacher-guided learning, the personal work of the learners and the working group. The project consists of the interactive didactic material electronic edition related to the subjects dealt with in the subject Geological Foundations (Degree of Engineering in Exploitation of Mines and Energy Resources) and Geology, (Degree in Engineering in Exploitation of Mines and Energy Resources). For this purpose, all the contents are integrated into a digital document with digital with sufficient links for the student to navigate throughout the subject. The objectives are: Compilation of the theoretical and practical contents of the subjects; Development and updating of a set of activities for the assimilation of the contents; Integration of all contents in a digital format document with sufficient links for student navigation throughout the subject; Incorporate links to websites of interest that allow the extension of the contents of the subject; Familiarize students with learning. To achieve the objectives proposed in the project, the following methodology is proposed: Phase I. Preparation of teaching material; Phase II Creation of an interactive virtual platform with the didactic material developed: Once all the didactic material has been developed and available, a navigation environment will be programmed with Frontpage (or similar) with which the student can easily access the developed contents. In this way, once all the didactic material has been prepared and available in digital format, a navigation environment will be programmed with which the student can be able to easily access the developed contents. With this didactic material, a publication will be made which will be easily accessible for all interested students. The student will have the theoretical contents developed, as well as a collection of representative problems solved, which will serve as a guide for the study of the subjects mentioned above. In addition, interactive tests will be carried out that allow the student to self-evaluate the theoretical-practical concepts worked on. In this way, this work can be considered as a first phase of the total virtualization of all the subjects

Preliminary results of ecotoxicological assessment of an Acid Mine Drainage (AMD) passive treatment system testing water quality of depurated lixiviates

The current work reports on the preliminary results of a toxicity test using screening experiments to check the efficiency of an innovative passive treatment plant designed for acid mine drainage purification. Bioassays took place with water samples before and after the treatment system and in the river, once treated water is discharged. Due to the high toxicity of the water collected at the mouth of the mine (before the treatment plant), the bioassay was designed and developed with respect to the exposed organism and the characteristics of the water. The results obtained in the screening experiment show the high efficiency of the treatment plant in terms of ecotoxicity, using Artemia sp. toxicity test

Physico-Chemical Influence of Surface Water Contaminated by Acid Mine Drainage on the Populations of Diatoms in Dams (Iberian Pyrite Belt, SW Spain)

Twenty-three water dams located in the Iberian Pyrite Belt were studied during March 2012 (early spring) in order to carry out an environmental assessment based on diatom communities and to define the relationships between these biological communities and the physico-chemical characteristics of the dam surface water. This is the first time that a diatom inventory has been done for dams a ected by acid mine drainage (AMD) in the Spanish part of the Iberian Pyrite Belt (IPB). It was found that the pH was the main factor influencing the behaviour of the diatom communities. Then, using a dbRDA approach it was possible to organize the aggrupation of diatoms into four groups in response to the physico-chemical conditions of the ecosystem, especially pH: (1) Maris, Aac, Gos, Cmora (pH 2–3); (2) Andc, San, And, Dpin (pH 3–4.5); (3) Gran, Pleon, Oliv, Lagu, Chan, SilI, SilII, Joya, Gar, Agrio, Camp, Corum (pH 4.5–6); (4) Herr, Diq I, Diq II (pH 6–7). The obtained results confirmed the response of benthic diatom communities to changes in the physico-chemical characteristics of surface water, and helped to understand the role of diatoms as indicators of the degree of AMD contamination in those 23 dams. Special attention was given to those that have an acidophilic or acid-tolerant profile (pH 2–3 and pH 3–4.5) such as Pinnularia aljustrelica, Pinnularia acidophila, Pinnularia acoricola and Eunotia exigua, which are the two groups found in the most AMD contaminated dams.Cuantificacíon de la carga metalica y sulfatos aportada por procesos AMD a embalses de la Faja Piritica Iberica: modelizacíon del processo y velocidades de colmatacíon” (CGL2010-21268-C02-01), Ministerio de Educación y Ciencia. “Cuantificacion de la carga metálica y sulfatos aportada por procesos AMD a embalses de la Faja Piritica Iberica” (P10-RNM-6570), Junta de Andalucía-Convocatoria Proyectos de Excelencia. Fundação para a Ciência e a Tecnologia (FCT), I.P. National funds in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19

Odiel River (SW Spain), a Singular Scenario Affected by Acid Mine Drainage (AMD): Graphical and Statistical Models to Assess Diatoms and Water Hydrogeochemistry Interactions

The Odiel River (SW Spain) is one of the most cited rivers in the scientific literature due to its high pollution degree, generated by more than 80 sulphide mines’ (mostly unrestored) contamination in the Iberian Pyritic Belt (IPB), that have been exploited for more than 5000 years. Along the river and its tributaries, the physico-chemical parameters and diatoms, from 15 sampling points, were analyzed in the laboratory. Physico-chemical parameters, water chemical analysis, together with richness and Shannon–Wiener indexes were integrated in a matrix. An initial graphical treatment allowed the definition and proposal of a functioning system model, as well as the establishment of cause–effect relationships between pollution and its effects on biota. Then, the proposed model was statistically validated by factor analysis. For acidic pH waters, high values of Eh, TDS, sulphate, ∑REE and ∑Ficklin were found, while diatomologic indicators took low values. Thus, factor analysis was a very effective tool for graphical treatment validation as well as for pollution–biota interaction models’ formulation, governed by two factors: AMD processes and water balance suffered by the studied river. As a novelty, the cause–effect relationships between high barium concentration and low diversity and richness were demonstrated in the IPB, for the first time: The authors are grateful to the Departments of Biology and Geosciences of the University of Aveiro, Portugal where diatom samples were identified. The authors are grateful to the Sustainable Mining Engineering Research Group, Department of Mining, Mechanic, Energetic and Construction Engineering at the Higher Technical School of Engineering, University of Huelva, Spain for paying for the water analyses. AT Luís is funded by national funds (OE), through FCT—Fundação para a Ciência e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of 29 August, changed by Law 57/2017, of 19 Jul

Estudio de la contaminación por drenajes ácidos de mina de las aguas superficiales en la cuenca del río Odiel (SO España)

La mayor parte de la cuenca del río Odiel se encuentra degradado por drenajes ácidos de mina. Entre los años 2002-2006 se realizó un estudio del estado de la contaminación en la cuenca del río Odiel junto con los de los embalses más importantes de la cuenca afectados por AMD. Como principales resultados se concluye que el 37% de la red hidrográfica se encuentra contaminada por metales pesados. Los mayores focos contaminantes proceden de las minas de Tharsis, Riotinto, La Lapilla y San Telmo. En los ríos Tinto y Odiel el arsénico se encuentra mayoritariamente en su especie As(V). En el río Tinto el As(III) representa el 0.5% mientras que en la cuenca del Odiel esta especie representa el 9%. Los embalses actúan como sumideros de contaminantes, produciendo una atenuación natural de la contaminación basada fundamentalmente en mecanismos de disolución y en la precipitación de sulfuros metálicos en las zonas anóxicas.Most of the Odiel River basin is affected by acid mine dranage. From 2002 to 2006, a study of the state of pollution was perfomed in the basin of the Odiel along with two of the most important water reservoirs. As main results we conclude that 37% of the hydrological network is polluted by heavy metals. The major sources of pollution are from Tharsis, Rio Tinto, The Lapìlla and San Telmo mines. In the rivers Tinto and Odiel arsenic is mostly in their species As (V). In the Tinto River As (III) represents 0.5% while in the Odiel basin this species represents 9%. Reservoirs act as sinks of contaminants, producing a natural attenuation of pollution mainly based mechanisms dilution and precipitation of metal sulfides in the anoxic zones