FCT; European Social Fundinfo:eu-repo/semantics/publishedVersio

Cordeiro, Mayara

Gomes, Patrícia

Grande, José António

Valente, Teresa Maria Fernandes

Universidade do Minho: RepositoriUM

XII CONGRESO NACIONAL Y XI IBÉRICO DE GEOQUÍMICAInvestigar los recursos cuidando el ambienteLinares (Jaén), 26 a 28 septiembre 2017178MAPPING MINING WASTES AND ANALYZING AFFECTED AREASTHROUGH EXPEDITIOUS PHYSICO-CHEMICAL PARAMETERSCordeiro, Mayaraa, Valente, Teresab, Grande, José Antonioc, Gomes, Patríciada University of Minho & Institute of Earth Sciences, Master student, email: mayaratcordeiro@gmail.com; b University of Minho & Institute of EarthSciences, Professor, e-mail: teresav@dct.uminho.pt; c University of Huelva, Professor, email: grangil@uhu.es; d University of Minho & Institute of EarthSciences, PhD student, email: fpssgomes@gmail.comABSTRACTIn the past, the large-scale exploitation of São Domingos mine,in the Portuguese sector of the Iberian Pyrite Belt, generatedenormous reactive waste dumps. The sulphide- richness of theseaccumulations has been responsible for degradation of the entireecosystem through the discharge of acidic leachates, veryenriched in sulfate and metals. Pyrite is the most abundantmineral, from which oxidation results this acid mine drainage.Nowadays, there are numerous waste dumps, of differentmining periods (from the roman until XX century), dispersedalong the entire mining complex. The wastes present highvariability in gran size and lithological composition, whichcontrols their reactivity and consequently their contaminantpotential. So, specifically, the present study shows a map of thewastes, at scale of 1:25,000, in order to analyze the nature ofwater changes induced by the solutions that are drained fromthe different types of waste accumulations.Key words: acid mine drainage, mapping, mining wastes,reactive materials, São Domingos, SW Portugal1. INTRODUCTIONThe mining complex of São Domingos is located in the northernpart of the Iberian Pyrite Belt (IPB) and was mined between 1857and 1966 for the production of pyrite, copper and sulfur (Matoset al., 2012). The intense mining activity produced considerableamounts of wastes, from which oxidation results extremely acidleachates with high content of sulphate, metals and metalloids,known as acid mine drainage (AMD) (Parker and Robertson,1999; Younger et al., 2002; Grande et al., 2016; Valente et al.,2016). The presence of secondary minerals in the waste dumpsand the drainage surfaces indicate that these materials are stillreactive and have environmental importance with regard to thesolubility and potentially toxic elements enclosing in its compo-sition. The final discharge of acid leachates reaches the Chançariver, main effluent of the Guadiana river, potentially affected bythis pollution (Álvarez-Valero et al., 2008). This work presentspreliminary results on mapping of the mining wastes and inanalyzing their properties, in order to understand the contribu-tion of different types of wastes to the water degradation. 2. MATERIALSFor mapping activities Garmin GPSMAP 76CSx was used. This ac-tivity was supported by the topographic map 559-Santana deCambas (1:25000), aerial photographs and the QGIS 2.12 soft-ware. Measuring of field physico-chemical parameters was achie-ved through multi-parameter meter (Orion 5 Star). Mining wasteswere collected and stored in plastic bags.3. METHODS3.1. SAMPLINGWater was collected once a month between October 2016 andJune 2017 in the following locations of the system: (PAT 1) waterfrom Tapada Grande, represents water that is not influenced bythe mine; (PAT 2) water from the pit lake; (PAT 3), (PAT 4), (PAT5), (PAT 6), (PAT 7) and (PAT 8) are sites directly influenced byAMD; (PAT 9) acid water dam; (PAT 10) immediately upstream ofthe confluence in the Chança river, (PAT 11) dispersion plume ofAMD in the river; (PAT 12) Chança water reservoir. Wastes werecollected in order to cover compositional variability.3.2. ANALYTICAL METHODS FOR WATERThe pH, electric conductivity (EC) and redox potential (Eh) of thewater samples were measured in the field with a multi-parame-ter meter (Orion 5 Star). 3.3. MAPPING AND ANALYTICAL METHODS FOR WASTESThe identification of the wastes and landfills in the field were co-eval to the cartographic activity. For the waste characterization,the pH and EC of the paste were obtained in a suspension of1:2.5, following the procedure described by Black (1965), X-raydiffraction was applied for mineralogical characterization of se-lected materials. Sulphur content was obtained by ICP-MS.4. RESULTS The Figure 1 illustrates the mapping of the wastes, which accu-mulations were classified in two categories: waste dumps (Ex)were considered as piles of different types of materials derivedfrom the mining and industrial activities, whereas landfills (Ax)represent accumulated materials that suffered transport, whichSESIÓN 6. GEOQUÍMICA AMBIENTAL, BIOGEOQUÍMICA Y CARTOGRAFÍA GEOQUÍMICAMapping mining wastes and analyzing affected areas through expeditious physico-chemical parameterswww.congresodegeoquimica.org 179WD Location Area (ha) Drainage direction General propertiesE1 N from the PL 1.87 PL and north Horizontal surface, medium to fine granulometry, black and redcolors, composed of old slags and gossan, very old wd andpartially re-vegetated.E2 NW from the PL 0.86 PL Compacted volcanics and shales.E3 NE from the PL 2.02 PL Group of small wd with heterogeneous granulometry andcomposition. Old slags mixed with material in process ofpedogenesis and material used in civil construction. Very oldwd and totally re-vegetated.E4 E from the PL 0.51 PL Volcanics and shales with heterometric granulometry.E5 SE from the PL 6.36 PL and stream Wd from distinctive periods overlapped,southwards heterogeneous material (shales) of fine to gross granulometry,from the PL re-vegetated.E6 E from the PL 0.08 PL Very thin material, light color.E7 S from the PL 2.5 PL Gossan with fine to medium particle size; re-vegetated.E8 W from the PL 0.41 Stream southwards Fine to very fine granulometry, great presence of secondaryfrom the PL oxides and sulfates of green and yellow colors (Cp and Jrs).E9 SW from the PL 7.48 PL and stream Major composition of cementation wastes (~ 80%). At the SWsouthwards from limit of this wd there are sulphide-rich materials and secondarythe PL minerals resulting from their alteration, predominantly Cp and Jrs.E10 NW from the PL 0.49 PL Washed Py, fine granulometry, there are also abundantquartz, Jrs and GthE11 W from the PL 2.1 PL Fine material, composed predominantly of modern slags,black color.E12 N from the PAT 4 3.1 PAT 4 Predominate fragments of shale, medium to grossgranulometry, sporadically occur large mineralized blocksthat show evidence of incipient oxidation and salinization.E13 NW from the church 1.5 Lagoon Shale with medium to gross granulometry, re-vegetated(planting of olive trees).E14 N from the PAT 6 2.11 AWS Old slag, medium to thick granulometry, black color.E15 E from the PAT 6 5.93 AWS Material very thin to fine, white to pale beige.E16 Between PAT 6 6.28 AWS Slag with granulometric variety, sand to pebble, black color andand PAT 7 with different degrees of roasting. There are portions wherethere is evidence of reactivity (gypsum) probably because theprocess was not complete, thus there were sulphides capable oforigin these salts. Ordinary slag has an inert, vitreous character,however in some portions (more exposed areas), there arereactions.E18 E from the PAT 7 1.55 PAT 7 and AWS Mixture of washed ore, Py ashes and Cp (the last can reachthicknesses of up to 10 cm). Sometimes they are distinguished,in the field, by the type of salinization that develops on theirsurface, in some cases white salts predominate, probablygypsum and iron sulphate (rozenite); in other cases the greensalt Cp is the most common one.E19 SE from the PAT 7 0.07 PAT 7 Old slag, medium to thick granulometry, black color.E20 S from the PAT 1 16.89 AWS Brownish shales, sometimes dark gray, with medium to thickgranulometry. This wd is partially re-vegetated.E21 SE from the PAT 1 1.42 PAT 3 Volcanics and clay shales with variable granulometry (mediumto thick) and light gray and light brown colors.E22 E from the PL 0.24 PL Old slag, medium to thick granulometry, black color.Note: WD: waste dump; PL: pit lake; AWS: acid water stream. Py: pyrite; Jrs: jarosite; Gth: goethite; Cp: copiapite.TABLE 1 – DESCRIPTION OF WASTE DUMPS WITH REFERENCE TO THE MAPXII CONGRESO NACIONAL Y XI IBÉRICO DE GEOQUÍMICAInvestigar los recursos cuidando el ambienteLinares (Jaén), 26 a 28 septiembre 2017180LF Location Area Drainage C or NC pH EC General properties(ha) direction paste pasteA1 Surrounding 14.6 PL and C 2.59 - 6.92 - Heterogeneous granulometry of various origins:PAT 3 PAT 3 3.07 7.21 tailings, residues from smelted ore, remains of oldmS/cm precipitates and iron oxides. There are strong evidences of acidity, like salinization (Al-Fe and sulphates, mainly at the landfill base) and filamentous algae. There is great abundance of Jrsas a cover over the rock fragments. Fragments ofjasper were also identified.A2 Stream 2.15 Stream NC - - Fine to very fine materials fromsouthwards southwards metallurgical treatment.from the PL from the PLA3 N from 1.37 Stream C 3.27 10.97 Very heterogeneous granulometry, predominancethe stream southwards mS/cm of highly oxidized material, very red color.southwards from the PL Features characteristics similar to the oxidizedfrom the PL material of E9.A4 W from 3.42 PL and NC - - Very heterogeneous material (volcanics andthe PL PAT 3 shales) and granulometry, not calcined, very highdegree of revegetation.A5 SW from the PL 3.31 Stream C 2.71 2.05 At the western boundary of this landfillsouthwards - 2.86 - 2.32 there is the formation of a depression where thefrom the PL mS/cm accumulation of very fine sediments is observed,with fine, beige color, deriving from transport.A6 W from PAT 4 1.92 PAT 4 C 2.51 7.70 Fine sediment deriving from the leaching of themS/cm surrounding landfills, providing the accumulationof fine material. Contaminant character evidencedby corrosion phenomena and the presence ofsupergenic neoformations, namely Jrs / Fe sulfates,besides the pH of the paste and of the finer residues.A7 E from 7.71 PL and NC - - Shale and gossan fragments withPAT 1 PAT 3 variable granulometry.A8 NW 2.71 Tapada NC - - Fragments of volcanics and shalesfrom PL Pequena with variable granulometry.and PLA9 NE from 3.49 PAT 3 and C 3.35 297 Predominantly fragments of shale nature, PAT 3 PAT 4 µs/cm sporadically occur large mineralized blocks thatshow signs of incipient oxidation and salinization.A10 S from 10.09 PAT 5 C 3.05 - 595 - Similar characteristics to A1: heterogeneousPAT 3 and AWS 3.31 1525 granulometry and diverse origins. There are alsoµs/cm recent precipitates, but there are scatteredaccumulations of old slag and a greater proportionof rocks with iron oxides, variable granulometryand a greater proportion of shales.A11 NE from 0.28 PAT 5 C Washed Py, fine granulometry, occurs coveringPAT 5 and AWS the debris deposited below (A10).A12 N from 1.76 AWS NC - - Shales, medium particle size, non reactive,PAT 6 without vegetation.A13 NW from 6.58 AWS NC - - Similar characteristics to A12, shale material,PAT 7 medium particle size, non reactive, withoutvegetation.A15 NE from 1.12 AWS nd Set of evaporation rafts used to recover FePAT 7 sulphate. TABLE 2 – DESCRIPTION OF LANDFILLSSESIÓN 6. GEOQUÍMICA AMBIENTAL, BIOGEOQUÍMICA Y CARTOGRAFÍA GEOQUÍMICAMapping mining wastes and analyzing affected areas through expeditious physico-chemical parameterswww.congresodegeoquimica.orgpresent location results from some kind of the use of the wastedumps. Both present high variability concerning grain size andcomposition. The waste dumps and landfills were described ac-cording to their attributes, such as occupied surface area, particlesize, color, main lithologies, physical stability, pH paste, EC pasteand state of revegetation, among others. Table 1 is an extract ofthe waste dumps inventory and Table 2 is concerned to the land-fills. The characterization of the landfills attended to their reactivenature, which is potentially responsible for AMD. So, criteria suchas pH of the paste and presence of salinization were used as in-dicators of the respective contaminant character: Contaminant(C) or not contaminant (NC).Figures 2 and 3 present average values of field parameters, illus-trating the influence of the discharge of AMD along the riversystem. For effects of better illustration, the mining complex wasdivided in two sectors. The North sector (Fig. 2) includes the ma-terials around the pit lake until the area of industrial treatment(Achada do Gamo), whereas the South sector shows the downs-tream area, until the confluence in the Chança reservoir. The lo-west values of pH, and highest EC and Eh were presented by PAT7 (Achada do Gamo), followed by PAT 2 (pit lake). Both sites areinfluenced by waste dumps, as shown in Figure 2, whose amountof sulphur is presented in Table 3. The most contaminated site,PAT 7, is surrounded by the waste dump E18, which were sam-pled in three different areas and presented the highest concen-trations of sulphur. Regarding to the PAT 2, six waste dumps wereanalyzed, and some of the samples also showed elevated con-centrations of sulphur. 181LF Location Area Drainage C or NC pH EC General properties(ha) direction paste pasteA16 E from 6.31 AWS nd Leaching tank with very fine, white to pale beige,PAT 6 material.A17 E from 11.23 PAT 7 NC - - Areas affected by old mining processes. fragmentsPAT 7 and AWS of rocks yellowish to reddish with some evidenceof oxidation - small portions of rocks with Fe oxide.Fragments of jasper, shale and volcanic. Incipientrevegetation where there is water A18 SW from 0.41 AWS C Heterogeneous material, identified shales andPAT 9 gossan fragments. The water drained by this landfillreaches a water line where there is the presence ofopaque and shiny white salts (gypsum), this waterline shows no evidence of acidity.A19 SE from 0.72 AWS NC - - Heterometric non-reactive heterogeneousPAT 9 fragments of shales and volcanics.A20 NE from 2.17 PAT 3 NC - - Heterometric fragments of volcanics and shales.PAT 3A22 S from 6.25 AWS - - - Area around the infrastructures of the Achada doPAT 7 Gamo and railway, with small lenticules ofheterogeneous material, namely washed Py(greater proportion), slag and oxidized materials.Note: LF: Landfill; PL: pit lake, C: contaminant; NC: not contaminant; nd: not determined; AWS: acid water stream; Py: pyrite; Jrs: jarosite.TABLE 2 – DESCRIPTION OF LANDFILLS (CONT)Figure 1 – Mapping of mining wastes.ference POCI-01-0145-FEDER-007690 and national funds provi-ded by FCT – Fundação para a Ciência e Tecnologia.7. REFERENCES- Álvarez-Valero, A.M., Pérez-López, R., Matos, J.X., Capitán,M.A., Nieto, J.M., Saez, R., Delgado, J., Caraballo, M. (2008).Potential environmental impact at São Domingos mining dis-trict (Iberian Pyrite Belt, SW Iberian Peninsula): evidence froma chemical and mineralogical characterization. EnvironGeololgy, 55, 1797–1809. - Black, C.A. (1965) (ed.) Methods of soil analysis. Part 2.Chemical and microbiological properties. Agronomy Series nº9, ASA, Madison, Wis.- Grande, J.A., de la Torre M.L., Valente T., Fernandez P., PérezOstalé, E. (2016). Spatial evolution of an AMD stream in theIberian Pyrite Belt: process characterization and control fac-tors on the hydrochemistry. Hydrological Sciences Journal,61:8, 1503-1511. XII CONGRESO NACIONAL Y XI IBÉRICO DE GEOQUÍMICAInvestigar los recursos cuidando el ambienteLinares (Jaén), 26 a 28 septiembre 20171825. CONCLUSIONSIn general, waste dumps and reactive landfills are the main focusof the contamination in São Domingos. The pH of the paste, thesulphur content as well as evidence of salinization are indicatorsof the contaminant character. In accordande, drainage from thesereactive sites is reponsible for the worst contamination scenario,observed in PAT 7. Thus, this point has an average pH of 1.86, ECof 14132.44 S/cm and Eh of 521.47 mV, followed by the pitlake (2.68 pH, EC 6939.22 S/cm, Eh 550.10 mV), both of themstrongly influenced by discharge of acidic leachates emergingfrom different types of waste dumps, including piles of fine grainpyrite.6. ACKNOWLEDGMENTThis work was co-funded by the European Union through theEuropean Regional Development Fund, based on COMPETE 2020(Programa Operacional da Competitividade eInternacionalização), project ICT (UID/GEO/04683/2013) with re-Figure 2 – Average values of physico-chemical parameters in re-presentative sampling points in the northern area.Figure 3 – Average values of physico-chemical parameters in re-presentative sampling points in the southern area.Drainage direction Waste Dump Total S (%) pH EC (S/cm) Eh (mV)PAT 2 - Pit lake E1 0,28E4 0,30E5 0,50E7 0,77E10 (oxidised) 11,20E10 (unoxidised) 1,26E11 3,20 2.68 6939.22 550.10PAT 7 - Achada do Gamo E18 6,75E18a 66,20E18b 10,50 1.86 14132.44 521.47TABLE 3 – DESCRIPTION OF LANDFILLSSESIÓN 6. GEOQUÍMICA AMBIENTAL, BIOGEOQUÍMICA Y CARTOGRAFÍA GEOQUÍMICAMapping mining wastes and analyzing affected areas through expeditious physico-chemical parameterswww.congresodegeoquimica.org- Matos, J. X., Pereira, Z., Batista, M. J., Oliveira, D. de. (2012).São Domingos mining site - Iberian Pyrite Belt. In 9thInternational Symposium on Environmental Geochemistry (pp7-12). Aveiro.- Parker, G., Robertson, A. (1999). Acid drainage. A critical re-view of acid generation from sulfide oxidation: processes, tre-atment and control. Australian Minerals & Energy EnvironmentFoundation, Occasional Paper, 11, 227.- Valente, T., Grande, J. A., Ceron, J. C., De La Torre, M. L.,Santisteban, M., Borrego, J., Fernández, P., Sánchez-Rodas, D.(2016). Spatial distribution of major and trace elements in amining dam: sources and relationships among elements ofenvironmental concern. Environment Earth Science, 75:342. - Younger, P. L., Banwart, S.A., Hedin, R.S. (2002). Mine water:hydrology, pollution, remediation. Kluwer, Dordrecht, 442.183

Mapping mining wastes and analyzing affected areas through expeditious physico-chemical parameters

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Mapping mining wastes and analyzing affected areas through expeditious physico-chemical parameters

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