Environmental Management of Aznalcóllar Mine and Its Influence in the Hydrogeochemical of the Pit lake
Since its 1995 closure and the subsequent 1998 accident, the Aznalcóllar mine pit has been used as a disposal site for diverse metal-rich materials, such as the polluted soils removed during the cleaning of areas along the Guadiamar River, waste rock, pyrite sludge, and ashes deriving from pyrite roasting. At present, the mining pit is partly flooded and contains a highly acidic (pH 2.7) pit lake with approximately 6 Mm3 of metal and sulphate-rich water. Recent detailed research performed in the area has proven that the reaction of the lake water with both the dumping mining wastes and the inflow of acid mine waters are strongly modifying the water quality of the pit lake. A major change was identified in the water quality that resulted from the dumping of 1.4 Mm3 of pyritic wastes during 2005 and 2006. The oxidative dissolution of this mineral has resulted in: (1) a total consumption of dissolved oxygen, (2) a notable increase of electric conductivity (from 8.6 to 12 mS/cm) and (3) a strong acidification (pH from 4.2 to 2.7) and an important heating that was observed as a result of the exothermic character of pyrite oxidation. Despite the total lack of oxidizing agents—such as O2 and Fe(III) (Fe[III] < 5% total Fe)—in the pit lake, pyrite is being oxidized with a continuous increase of the SO4 2- and Fe concentrations.
Document Type: Research Article
Publication date: 2013-08-01
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Water Environment Research� (WER�) publishes peer-reviewed research papers, research notes, state-of-the-art and critical reviews on original, fundamental and applied research in all scientific and technical areas related to water quality, pollution control, and management. An annual Literature Review provides a review of published books and articles on water quality topics from the previous year. Published as: Sewage Works Journal, 1928 - 1949; Sewage and Industrial Wastes, 1950 - 1959; Journal Water Pollution Control Federation, 1959 - Oct 1989; Research Journal Water Pollution Control Federation, Nov 1989 - 1991; Water Environment Research, 1992 - present.
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