Geochemical and mineralogical control on the mobility of arsenic in a waste rock pile at Dlouhá Ves,Czech Republic |
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| Authors: | E Kocourková O Sracek S Houzar J Cempírek Z Losos J Filip P Hršelová |
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| Institution: | 1. Department of Mineralogy and Petrography, Moravian Museum, Zelný trh 6, 659 37 Brno, Czech Republic;2. Institute of Geological Sciences, Faculty of Science, Masaryk University, Kotlá?ská 2, 611 37 Brno, Czech Republic;3. Department of Geology, Faculty of Science, Palacký University, 17. Listopadu 12, 771 46 Olomouc, Czech Republic;4. OPV s.r.o. (Protection of Groundwater Ltd), Bělohorská 31, 169 00 Praha 6, Czech Republic;5. Regional Centre of Advanced Technologies and Materials, Palacký University, Šlechtitel? 11, 783 71 Olomouc, Czech Republic |
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| Abstract: | A waste rock pile with initial high sulfide (10–20 wt.%) and low carbonate content (1–2 wt.%) located at Dlouhá Ves in the Czech Republic has been investigated in two profiles (excavation and outcrop) using powder X-ray diffraction, electron microprobe analysis, bulk composition analysis and Mössbauer spectroscopy. The mobility of arsenic and other contaminants was evaluated by leaching experiments. The primary source of the arsenic was arsenopyrite, which was significantly oxidized in both profiles. The principal As-bearing phase at the excavation profile was goethite, located at the top of the profile, and minerals of the jarosite group which were found down to its base. Melanterite, rich in copper and zinc, was found in a sulfide-rich, lower part of the profile together with anglesite. At the outcrop profile, minerals of the jarosite–beudantite group, scorodite and kaňkite prevail and no Fe(II)-minerals were found. The paste pH was lower at the excavation profile (minimum about 1.9) than at the outcrop profile (minimum of about 2.8). Processes in the pile are affected by the pyrite/arsenopyrite ratio, where high pyrite content decreases the As/S ratio and results in the formation of jarosite group minerals and low pH conditions. Where arsenopyrite predominates, sulphides are coated by scorodite and other Fe–As phases like schwertmannite, which limit their further oxidation. |
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| Keywords: | Waste rock Arsenic Scorodite Jarosite Arsenic mobilization |
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