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Eger, P., Melchert, G., & Wagner, J. (2000). Using passive treatment systems for mine closure – A good approach or a risky alternative? Min. Eng., 52(9), 78–83.
Abstract: In 1991, LTV Steel Mining decided to close an open-pit taconite mine in northeastern Minnesota using a passive-treatment approach consisting of limiting infiltration into the stockpiles and wetland treatment to remove metals. More than 50 Mt (55 million st) of sulfide-containing waste had been stockpiled adjacent to the mine during its 30 years of operation. Drainage from the stockpiles contained elevated levels of copper, nickel, cobalt and zinc. Nickel is the major trace metal in the drainages. Before the closure, the annual median concentrations ranged from 1.5 to 50 mg/L. Copper, cobalt and zinc are also present but they are generally less than 5% of the nickel values. Median pH levels range from 5 to 7.5, but most of the stockpile drainages have pH levels greater than 6.5. Based on the chemical composition of each stockpile, a cover material was selected. The higher the potential that a stockpile had to produce acid drainage, the lower the permeability of the capping material required. Covers ranged from overburden soil removed at the mine to a flexible plastic liner. Predictions of the reduction in infiltration ranged from 40% for the native soil to more than 90% for the plastic liner. Five constructed wetlands have been installed since 1992. They have removed 60% to 90% of the nickel in the drainages. Total capital costs for all the infiltration reduction and wetlands exceeded $6.5 million, but maintenance costs are less than 1% of those for an active treatment plant. Because mine-drainage problems can continue for more than 100 years, the lower annual operating costs should pay for the construction of the wetland-treatment systems within seven years.
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Sottnik, P., & Sucha, V. (2001). Moznosti upravy kysleho banskeho vytoku loziska Banska Stiavnica-Sobov. Remediation of acid mine drainage from Sobov Mine, Banska Stiavnica. Mineralia Slovaca, 33(1), 53–60.
Abstract: A waste dump formed during the exploitation of quartzite deposit in Sobov mine (Slovakia) produces large quantity of acid mine drainage (AMD) which is mainly a product of pyrite oxidation. Sulphuric acid--the most aggressive oxidation product--attacks gangue minerals, mainly clays, as well. This process lead to a sharp decrease of the pH values (2-2.5) and increase of Fe, Al and SO (super 2-) (sub 4) contents (TDS = 20-30 mg/1). Passive treatment system was designed to remediate AMD. Chemical redox reactions along with microbial activity cause a precipitation of mobile contamination into a more stable forms. The sulphides are formed in the anaerobic cell, under reducing conditions. Fe-, Al- oxyhydroxides are precipitated in the aerobic part of the system. Precipitation decreases the Fe and Al contents along with immobilization of some heavy metal closely related to oxyhydroxides. Besides oxidation, the wetland vegetation is an active part of on aerobic cell. The system has been working effectively since September 1999. The pH values of outflowing water are apparently higher (6.2-6.8) and contents of dissolved elements (Fe from 2.260 to 4.1; Al from 900 to 0.18; Mn from 51 to 23; Cu from 4.95 to 0.03 mg/l) is significantly lowers.
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Adam, K. (2003). Solid wastes management in sulphide mines: From waste characterisation to safe closure of disposal sites. Minerals and Energy Raw Materials Report, 18(4), 25–35.
Abstract: Environmentally compatible Waste Management schemes employed by the European extractive industry for the development of new projects, and applied in operating sulphide mines, are presented in this study. Standard methodologies used to assess the geotechnical and geochemical properties of the solid wastes stemming from mining and processing of sulphidic metal ores are firstly given. Based on waste properties, the measures applied to ensure the environmentally safe recycling and disposal of sulphidic wastes are summarised. Emphasis is given on the novel techniques developed to effectively prevent and mitigate the acid drainage phenomenon from sulphidic mine wastes and tailings. Remediation measures taken to minimise the impact from waste disposal sites in the post-closure period are described.
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Camus, M. (1997). Le traitement des eaux de mine desaffectees. Die Aufbereitung von Wässern aus stillgelegten Bergwerken. Treating water from closed mines. Mines et Carrieres, (Feb), 38–39.
Abstract: In einem alten französischen Bergwerk, in dem früher Blei und Silber abgebaut wurden, kam es nach dem Wiederanstieg des Grundwassers zu einer erhöhten Schwermetallbelastung von Quellgebieten, die einen Fluß mit Forellenbesatz schädigten. Zur Beseitigung dieser Grundwasserverunreinigung wurde das saure Grubenwasser mit erhöhten Eisen- und Zinkgehalten übertage gefaßt und einer Wasseraufbereitung unterzogen. In der für einen Durchsatz von 100 m(exp 3)/h konzipierten Wasseraufbereitung wurden die Schadstoffbestandteile durch Oxidation und anschließende Neutralisation mit Kalk (Anhebung des pH-Wertes auf 8,2 bis 8,3) gefällt, durch Zugabe eines Flockungsmittels gebunden und die Schlammbestandteile anschließend einem Eindicker und Filterpressen zugeführt. Der Kalkverbrauch wird mit 240 kg/d angegeben. Die tabellarisch zusammengestellten Analysenergebnisse zeigen, daß die Wasseraufbereitung einen sehr guten Wirkungsgrad hatte. Neben einer Anhebung des pH-Wertes von 6,5 auf 8,2 konnten die Schwermetallgehalte bei Fe von 22 mg/l auf 0,09 mg/l und bei Zn von 38 mg/l auf 0,4 mg/l abgesenkt werden.
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Rees, B., Bowell, R., Dey, M., & Williams, K. (2001). Passive treatment; a walk away solution? Mining Environmental Management, 9(2), 7–8.
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