Field study of geochemistry and solute fluxes in flooded uranium mine tailings

2002 ◽  
Vol 39 (2) ◽  
pp. 357-376 ◽  
Author(s):  
Vicky Peacey ◽  
Ernest K Yanful ◽  
Roger Payne
Keyword(s):  
Pore Water ◽  
Mine Tailings ◽  
Diffusion Flux ◽  
Metal Mobility ◽  
Oxidation Products ◽  
Uranium Mine ◽  
Dissolved Metals ◽  
Dissolved Solids ◽  
Solute Fluxes ◽  
Water Cover

A geochemical investigation was conducted at the Quirke cell 14 mine waste management area near Elliot Lake, Ontario, Canada, to assess the evolution of water quality of submerged preoxidized uranium mine tailings. Dissolved solids, sulphate, and radium fluxes towards the water cover were calculated using measured solute concentrations, water-cover volumes, and seepage rates for 1993 and 1999. Results indicate that flooding of preoxidized tailings can lead to the initial release of dissolved solids, acidity, and sulphate from the tailings to the overlying water cover. However, the overall impact of this release on the water cover can be minimal in the long term because of dilution from precipitation and fresh water inflows and flushing of the oxidation products down into the pore water. Profiles of dissolved metals and sulphate across the tailings–water interface at the study site indicated a high degree of chemical stability. Solute concentrations in the water cover were homogeneous and generally low at all stations. Pore-water profiles revealed minor remobilization of some trace metals and radionuclides in the shallow pore water (~0.15 m).Key words: mine tailings, water cover, pore-water geochemistry, radium, metal mobility, diffusion, flux.

Field evidence of resuspension in a mine tailings pond

2001 ◽  
Vol 38 (4) ◽  
pp. 796-808 ◽  
Author(s):  
Celestina Adu-Wusu ◽  
Ernest K Yanful ◽  
Mohammed H Mian
Keyword(s):  
Shear Stress ◽  
Mine Tailings ◽  
Critical Shear Stress ◽  
Field Measurements ◽  
Shear Stresses ◽  
Wind Speeds ◽  
Tailings Pond ◽  
Field Evidence ◽  
Water Cover ◽  
Solubility Of Oxygen

Flooding of tailings under shallow water covers is an effective method of decommissioning potentially acid generating mine tailings. The low diffusivity and solubility of oxygen in water are attractive features of this technology. However, wind-induced waves can resuspend flooded tailings and expose them to greater contact with dissolved oxygen, thereby increasing the potential for oxidation and acid generation. Field measurements of wind activity and waves under different water cover depths and associated resuspension for a mine tailings pond in Ontario are presented and discussed. The results show that wind speeds greater than 8 m/s above water covers that are shallower than 1 m create waves of height greater than 10 cm and bottom shear stresses greater than 0.2 Pa. Under these conditions the critical shear stress of the mine tailings was exceeded, resulting in erosion and subsequent resuspension.Key words: mine tailings, water cover, wind-induced waves, resuspension, wind speed, shear stress.

Ecological amendment of uranium mine tailings using native plant species

2021 ◽  
pp. 249-261
Author(s):  
Lal Singh ◽  
Prafulla Soni ◽  
T. Mohan Manu
Keyword(s):  
Plant Species ◽  
Mine Tailings ◽  
Uranium Mine ◽  
Native Plant ◽  
Native Plant Species

Characteristics of the Acidity in Acid Sulfate Soil Drainage Waters, McLeods Creek, Northeastern NSW, Australia

2006 ◽  
Vol 3 (3) ◽  
pp. 225 ◽  
Author(s):  
Rosalind Green ◽  
T. David Waite ◽  
Michael D. Melville ◽  
Ben C. T. Macdonald
Keyword(s):  
Oxidation Products ◽  
Metal Species ◽  
Acid Sulfate Soils ◽  
Iron Sulfides ◽  
Dissolved Metals ◽  
Species Determination ◽  
Acid Sulfate ◽  
Direct Titration ◽  
Sulfate Soils ◽  
Drainage Waters

Environmental Context. Acid sulfate soils are found in many low-lying coastal areas, but they can also be encountered in inland areas of Australia and other parts of the world. These soils typically contain iron sulfides, primarily pyrite (FeS2) and mackinawite (FeS), and the products that result from oxidation of these iron minerals. Acidic and metal-rich waters can be produced when the pyrite in soil is oxidized by natural means or accelerated when the soil is drained, which typically occurs when it is developed for agriculture or urban use. In general, acid sulfate soils become a problem when oxidation products are transported from the soil profile into nearby streams and estuaries, which can severely affect the ecology, biodiversity, economic development, and the aesthetics of adjacent waterways. The key contributors to acidity in drainage waters from the site examined are Al3+, AlSO4– and, under particular circumstances, Mn2+ and Fe2+, but the principal species contributing to acidity are strongly time variant and would be expected to vary from site to site. Abstract. Catchments that contain acid sulfate soils can discharge large quantities of acid and dissolved metals into waterways. At McLeods Creek in far northern NSW, Australia, the acidity from the hydrolysis of dissolved metal species, particularly aluminium and iron, contributes to greater than 70% of the total acidity. Therefore, a poor relationship exists between both calculated and titrated acidity and pH because of the dominant influence of these hydrolyzable metal species. Determination of the so-called ‘cold acidity’ by direct titration with NaOH yields results that are difficult to replicate because of the buffering effects of suspended solids, carbon dioxide ingassing, and/or MnII and FeII oxidation in the sample as the titration end-point is approached. Samples that are pre-treated with sulfuric acid and hydrogen peroxide produce results (of ‘hot acidity’) that can be easily replicated and are similar to calculated acidities based on elemental analysis and speciation calculations. The cold acidity values for titrations of 105 water samples from the chosen field site are often higher than hot acidity values as a result of the loss of carbonate acidity during pre-treatment of samples for hot acidity analysis.

Mobility of Ra-226 and Heavy Metals (U, Th and Pb) From Pyritic Uranium Mine Tailings Under Sub-Aqueous Disposal Conditions

2011 ◽  
Author(s):  
Nand K. Dave´
Keyword(s):  
Heavy Metals ◽  
Surface Water ◽  
Mine Tailings ◽  
Ion Concentration ◽  
Uranium Mine ◽  
Acid Generation ◽  
Shallow Zone ◽  
Acidic Conditions ◽  
Waste Repositories

Laboratory lysimeter studies were undertaken to evaluate the leaching characteristics and mobility of Ra-226 and other heavy metals (U, Th and Pb) from pyritic uranium mine tailings under sub-aqueous disposal conditions for assessing the long-term radiological stability of such waste repositories. The experiments were conducted using three types of un-oxidized tailings: fine, coarse and gypsum depleted mill total tailings. The results showed that Ra-226 was leached from surface of the submerged tailings and released to both surface water and shallow zone pore water during initial low sulphate ion concentration of the surface water cover in all three cases. The release of Ra-226 was further enhanced with the onset of weak acidic conditions in the surface water covers of both coarse and gypsum depleted mill total tailings. With additional acid generation and increasing sulphate and iron concentrations, the dissolved Ra-226 concentrations in the water covers of these tailings gradually decreased back to low levels. Pb was also leached and mobilized with the development of moderate acidic conditions at the surface of the submerged coarse and gypsum deplete tailings. No leaching of U and Th was observed.

Migration of acidic pore waters at the Waite Amulet tailings site near Rouyn–Noranda, Quebec, Canada

1992 ◽  
Vol 29 (3) ◽  
pp. 466-476 ◽  
Author(s):  
Ernest K. Yanful ◽  
Luc C. St-Arnaud
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Water ◽  
Mine Drainage ◽  
Geotechnical Properties ◽  
Horizontal Flow ◽  
Sulphide Mineral ◽  
Saturated Zone ◽  
Pore Waters ◽  
Dissolved Metals ◽  
Water Contents

Pore waters found in the unsaturated zone of the Waite Amulet tailings have been modified by sulphide mineral oxidation, resulting in acidic pH (near 4) and high concentrations of dissolved iron and sulphate at about 5 and 12 g/L, respectively. These pore waters have been displaced down into the shallow saturated zone of the tailings by infiltrating water. Most metals are removed from the pore water as a result of pH buffering before they reach the deeper saturated zone. However, some dissolved metals still remain in solution and are transported with the pore water through the tailings. Numerical flow modelling shows that an anisotropy in hydraulic conductivity (ratio of Kx/Ky is estimated to be 100) exists in the tailings, most likely due to the presence of horizontal fine-grained "slime" layers. The estimated horizontal pore-water velocity is almost 20 times higher than the vertical velocity. Anisotropy in hydraulic conductivity has the effect of promoting horizontal flow over vertical flow in the model. The geometry of the tailings impoundment and the assumed impermeability of the varved clay soil underlying the tailings also contribute to increased horizontal flow. To verify that a preferred horizontal flow exists and that the clay subsoil is indeed impermeable, the geotechnical properties and hydrogeochemistry of the clay are also evaluated. The results indicate that clay located beneath the tailings is slightly overconsolidated in the shallow zone but normally consolidated at greater depth by the weight of the tailings. Overconsolidation ratios reach a maximum value of 2.0. In the clay–tailings interface zone, the soil is characterized by lower in situ water contents and slightly higher undrained shear strengths Cu than the deeper clay. The water contents of the near-interface clay average about 40% and the Cu values 80 kPa, compared with an average water content of 55% and a Cu value of only 20 kPa for the clay at greater depths. These geotechnical properties confirm the presence of a desiccated oxidized upper zone identified in previous studies. It is hypothesized that fractures that could have appeared in the oxidized zone before the tailings deposition would have been closed due to consolidation by the tailings mass. Above-background sulphate concentrations observed in the clay layer at a depth of 1 m are believed to be controlled by diffusion and advection. The presence of fractures in the oxidized zone and excess pore-water pressures generated during consolidation of the clay by the tailings mass could have also influenced chemical transport. Key words : acid generation, acid mine drainage, diffusion, geotechnical, hydrogeochemistry, tailings.

Study of the Oxidation State of Arsenic and Uranium in Individual Particles From Uranium Mine Tailings, Hungary

2007 ◽  
Author(s):  
A. Alsecz ◽  
J. Osa´n ◽  
J. Pa´lfalvi ◽  
I. Sajo´ ◽  
Z. Ma´the´ ◽  
...  
Keyword(s):  
Oxidation State ◽  
Mine Tailings ◽  
Track Detector ◽  
Uranium Mine ◽  
Nuclear Track Detector ◽  
Mobile Form ◽  
Edge Structure ◽  
X Ray ◽  
Uranium Ore ◽  
Distribution Of Elements

Uranium ore mining and milling have been terminated in the Mecsek Mountains (southwest Hungary) in 1997. Mine tailings ponds are located between two important water bases, which are resources of the drinking water of the city of Pe´cs and the neighbouring villages. The average U concentration of the tailings material is 71.73 μg/g, but it is inhomogeneous. Some microscopic particles contain orders of magnitude more U than the rest of the tailings material. Other potentially toxic elements are As and Pb of which chemical state is important to estimate mobility, because in mobile form they can risk the water basis and the public health. Individual U-rich particles were selected with solid state nuclear track detector (SSNTD) and after localisation the particles were investigated by synchrotron radiation based microanalytical techniques. The distribution of elements over the particles was studied by micro beam X-ray fluorescence (μ-XRF) and the oxidation state of uranium and arsenic was determined by micro X-ray absorption near edge structure (μ-XANES) spectroscopy. Some of the measured U-rich particles were chosen for studying the heterogeneity with μ-XRF tomography. Arsenic was present mainly in As(V) and uranium in U(VI) form in the original uranium ore particles, but in the mine tailings samples uranium was present mainly in the less mobile U(IV) form. Correlation was found between the oxidation state of As and U in the same analyzed particles. These results suggest that dissolution of uranium is not expected in short term period.

Preliminary risk assessment of the wet landscape option for reclamation of oil sands mine tailings: Bioassays with mature fine tailings pore water

2001 ◽  
Vol 16 (3) ◽  
pp. 197-208 ◽  
Author(s):  
Robert E. A. Madill ◽  
Monika T. Orzechowski ◽  
Guosheng Chen ◽  
Brian G. Brownlee ◽  
Nigel J. Bunce
Keyword(s):  
Risk Assessment ◽  
Pore Water ◽  
Mine Tailings ◽  
Oil Sands ◽  
Mature Fine Tailings ◽  
Fine Tailings
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