Arsenic readily released to pore waters from buried mill tailings |
| |
| Affiliation: | 1. Hydrologic Consultants, Inc., 143 Union Blvd., Suite 525, Lakewood, CO 80228, USA;2. Hydrochem Systems Corp., P.O. Box 17090, Golden, CO 80402, USA;3. Department of Chemistry and Biochemistry, University of Regina, 3737 Wascana Way, Regina, SK, Canada S4S 0A2;4. COGEMA Resources, Inc., P.O. Box 9204, Saskatoon, SK, Canada S7K 3X5;1. Center for Oceans and Human Health, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA;2. Department of Biology, University of Miami, Coral Gables, FL, USA;3. Division of Marine Geology and Geophysics, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, FL, USA;4. Department of Geological Sciences, University of Miami, Coral Gables, FL, USA;5. Division of Applied Marine Physics, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA;6. Department of Civil, Architectural, and Environmental Engineering, University of Miami, Coral Gables, FL, USA;1. Waite Research Institute, School of Agriculture, Food and Wine, University of Adelaide, Waite Rd, SA 5064, Australia;2. CSIRO Land and Water, Contaminant Chemistry and Ecotoxicology Program, Minerals Down Under Flagship, Waite Campus, Waite Rd, SA 5064, Australia;3. Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095, Australia;4. National Risk Management Research Laboratory, US EPA, Cincinnati, US;1. Institute of Chemical Technology, Department of Biotechnology, Prague 16628, Czech Republic;2. Charles University, Department of Biochemistry, Prague 12840, Czech Republic;3. University of North Dakota, Department of Chemistry, Grand Forks, ND 58202, USA;1. Technische Universität München, Chair of Urban Water Systems Engineering, Am Coulombwall, D-85748 Garching, Germany;2. Technische Universität München, Chair for Hydraulic and Water Resources Engineering, Arcisstr. 21, D-80333 München, Germany;3. Karlsruhe Institute of Technology, Engler-Bunte-Institut for Water Chemistry and Water Technology, Engler-Bunte-Ring 1, D-76131 Karlsruhe, Germany;1. Environmental Simulation and Pollution Control State Key Joint Laboratory, and State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (MARC), School of Environment, Tsinghua University, Beijing 100084, PR China;2. Shenzhen Laboratory of Microorganism Application and Risk Control, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, PR China |
| |
| Abstract: | At the McClean Lake Operation in the Athabasca Basin of northern Saskatchewan, the untreated acid raffinate solutions associated with U mill tailings contain up to 700 mg/L dissolved As. To reduce the concentration of As and other contaminants in acid tailing slurries at the JEB mill at McClean Lake, ferric sulfate may be added to the acid raffinates to assure that their molar Fe/As ratio equals or exceeds 3. Tailings slurries are then neutralized with lime to pH 4, and subsequently to pH 7–8. The neutralized tailings contain minerals from the original ore, which are chiefly quartz, illite, kaolinite and chlorite, and precipitated (secondary) minerals that include gypsum, scorodite, annabergite, hydrobasaluminite and ferrihydrite. Most of the As is associated with the secondary arsenate minerals, scorodite and annabergite. However, a few percent is adsorbed and/or co-precipitated, mainly by ferrihydrite. Of major concern to provincial and federal regulators is the risk that significant amounts of As might be released from the tailings to pore waters after their subaqueous disposal in the tailings management facility. A laboratory study was performed to address this issue, measuring readily desorbed As using a method known as equilibrium partitioning in closed systems (EPICS). The EPICS method was selected because it employs a leaching solution that, except for its As concentration, is identical in composition to the neutralized raffinate in contact with the tailings. Laboratory experiments and modeling results demonstrated that the As that could be readily released to pore waters is about 0.2% of the total As in the tailings. Long-term, such releases may contribute no more than a few mg/L of dissolved As to tailings pore waters. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
