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Conca, J. L., & Wright, J. (2006). An Apatite II permeable reactive barrier to remediate groundwater containing Zn, Pb and Cd. Appl. Geochem., 21(12), 2188–2200.
Abstract: Phosphate-induced metal stabilization involving the reactive medium Apatite II(TM) [Ca10-xNax(PO4)6-x(CO3)x(OH)2], where x < 1, was used in a subsurface permeable reactive barrier (PRB) to treat acid mine drainage in a shallow alluvial groundwater containing elevated concentrations of Zn, Pb, Cd, Cu, SO4 and NO3. The groundwater is treated in situ before it enters the East Fork of Ninemile Creek, a tributary to the Coeur d'Alene River, Idaho. Microbially mediated SO4 reduction and the subsequent precipitation of sphalerite [ZnS] is the primary mechanism occurring for immobilization of Zn and Cd. Precipitation of pyromorphite [Pb10(PO4)6(OH,Cl)2] is the most likely mechanism for immobilization of Pb. Precipitation is occurring directly on the original Apatite II. The emplaced PRB has been operating successfully since January of 2001, and has reduced the concentrations of Cd and Pb to below detection (2 μg L-1), has reduced Zn to near background in this region (about 100 μg L-1), and has reduced SO4 by between 100 and 200 mg L-1 and NO3 to below detection (50 μg L-1). The PRB, filled with 90 tonnes of Apatite II, has removed about 4550 kg of Zn, 91 kg of Pb and 45 kg of Cd, but 90% of the immobilization is occurring in the first 20% of the barrier, wherein the reactive media now contain up to 25 wt% Zn. Field observations indicate that about 30% of the Apatite II material is spent (consumed).
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Märten, H. (2006). Neueste Trends zur aktiven Wasserbehandlung und Anwendungsbeispiele. Wissenschaftliche Mitteilungen, 31, 13–22.
Abstract: Aktuelle Entwicklungen auf dem Gebiet der aktiven Wasserbehandlung im Bergbau in den spezifischen Anwendungsgebieten • Behandlung von sauren Bergbauwässern (AMD – acidic mine drainage) mit Schwerpunkt HDS-Technologie (HDS – high-density sludge) • In-situ-Behandlung bergbaubeeinflusster Grundwasserkörper, insbesondere nach Anwendung der In-situ-Laugung (ISL) • In-situ-Behandlung von Tagebaurestseen mit Schwerpunkt In-lake-Verfahren werden hinsichtlich Machbarkeit, technologischer Kenngrößen und Effizienz bewertet und kommen-tiert. Recent developments in the field of active water treatment technologies in the mining sector are re-viewed. Application areas of interest include • Treatment of acidic mine drainage (AMD) emphasizing HDS technology (HDS – high-density sludge) • In-situ treatment of groundwater affected by mining, in particular after the application of in-situ leaching (ISL) • In-situ treatment of lakes arising in former open-pit lignite mines, in particular the application of in-lake methods The various applications are evaluated with regard to feasibility, technical characteristics and treat-ment efficiency.
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