Showing papers on "Tailings published in 2005"

In situ bioremediation of naphthenic acids contaminated tailing pond waters in the athabasca oil sands region--demonstrated field studies and plausible options: a review.

Abstract: Currently, there are three industrial plants that recover oil from the lower Athabasca oil sands area, and there are plans in the future for several additional mines. The extraction procedures produce large volumes of slurry wastes contaminated with naphthenic acids (NAs). Because of a "zero discharge" policy the oil sands companies do not release any extraction wastes from their leases. The process-affected waters and fluid tailings contaminated with NAs are contained on-site primarily in large settling ponds. These fluid wastes from the tailing ponds can be acutely and chronically toxic to aquatic organisms, and NAs have been associated with this toxicity. The huge tailings containment area must ultimately be reclaimed, and this is of major concern to the oil sands industry. Some reclamation options have been investigated by both pioneering industries (Syncrude Energy Inc. and Suncor Inc.) with mixed results. The bioremediation techniques have limited success to date in biodegrading NAs to levels below 19 mg/L. Some tailing pond waters have been stored for more than 10 years, and it appears that the remaining high molecular weight NAs are refractory to the natural biodegradation process in the ponds. Some plausible options to further degrade the NAs in the tailings pond water include: bioaugmentation with bacteria selected to degrade the more refractory classes of NAs; the use of attachment materials such as clays to concentrate both the NA and the NA-degrading bacteria in their surfaces and/or pores; synergistic association between algae and bacteria consortia to promote efficient aerobic degradation; and biostimulation with nutrients to promote the growth and activity of the microorganisms.

Naphthenic acids in athabasca oil sands tailings waters are less biodegradable than commercial naphthenic acids.

Abstract: Naphthenic acids (NAs) are natural constituents in many petroleum sources, including bitumen in the oil sands of Northern Alberta, Canada. Bitumen extraction processes produce tailings waters that cannot be discharged to the environment because NAs are acutely toxic to aquatic species. However, aerobic biodegradation reduces the toxic character of NAs. In this study, four commercial NAs and the NAs in two oil sands tailings waters were characterized by gas chromatography−mass spectrometry. These NAs were also incubated with microorganisms in the tailings waters under aerobic, laboratory conditions. The NAs in the commercial preparations had lower molecular masses than the NAs in the tailings waters. The commercial NAs were biodegraded within 14 days, but only about 25% of the NAs native to the tailings waters were removed after 40−49 days. These results show that low molecular mass NAs (C ≤ 17) are more readily biodegraded than high molecular mass NAs (C ≥ 18). Moreover, the results indicate that biodegra...

Natural Colonization of Plants on Five Lead/Zinc Mine Tailings in Southern China

Abstract: Mine tailings can have a specific assemblage of plant species due to their unique physicochemical properties, and this process can be important in developing ecological theory and restoration practice. Physicochemical properties and natural colonization of plants on five lead/zinc (Pb/Zn) mine tailings in southern China were investigated. The tailings studied included Fankou and Lechang in Guangdong Province, and Huangshaping, Shuikoushan, and Taolin in Hunan Province. Physicochemical properties of the tailings varied greatly both among and within tailings ponds, but in general, all contained high concentrations of heavy metals (Pb, Zn, Cu, and Cd) and low concentrations of N, P, and organic matter. Toxic levels of heavy metals and deficiency of major nutrients appeared to be the major constraints for colonization of plants on these Pb/Zn tailings and were reflected in the metal concentration of the plant tissues. The natural colonization of plants on these tailings was limited, with only some small patches distributed mainly on the edge of tailing ponds and even fewer patches on the center of the ponds. In total 54 plant species belonging to 51 genera and 24 families were recorded on the five tailings ponds, of which the 13 species belonging to Gramineae were major components of the tailings’ flora. Species establishing on the tailings at the initial colonization phase greatly depended on their seed-dispersal capacity. Further establishment and growth were then dependent on at least one of the three ecological strategies: (1) microsite (avoidance) strategy: plant establishment on tailings depended on dispersing onto microsites of relatively favorable edaphic conditions; (2) tolerance strategy: plant establishment was a result of evolving metal-tolerant ecotypes or constitutional metal tolerance; and (3) rhizome strategy: plant establishment on tailings depended on clonal growth by rhizomatous extension.

Cyclic shear response of fine-grained mine tailings

Abstract: The mechanical response of three different types of fine-grained mine tailings is examined using data from constant-volume cyclic direct simple shear (DSS) tests. Under cyclic DSS loading, fine-gra...

Causes and consequences of the Merriespruit and other tailings-dam failures

Abstract: On the night of 22 February 1994, the 31 m high northern wall of the number four tailings dam of the Harmony Gold mine collapsed. The tailings dam is situated 320 m up-slope of Merriespruit, a suburb of Virginia in the Free State Goldfields of South Africa. More than 2·5 million tonnes of liquefied tailings ripped through the sleeping mining village. Eighty houses were largely swept away and 200 others were severely damaged. Seventeen people were killed. The failure of this tailings dam shocked everybody who followed the unfolding drama of loss of life and destruction of property in the press. At the inquest following the disaster, the judge called this tailings dam a time bomb that was waiting to explode. For the first time in South African history, processed satellite images were allowed as scientific evidence in court. Together with eyewitness reports, all the evidence pointed overwhelmingly to the cause of the failure as being overtopping. The owner, the operator and six of their employees were subsequently found guilty of negligence and heavy fines were imposed. The Merriespruit disaster provided the State and the mining industry with the impetus to ensure the safe disposal of tailings. It also made the mining industry and all those involved with the design and operation of tailings dams take stock of their management and tailing disposal methods. Copyright © 2005 John Wiley & Sons, Ltd.

Biofilm formation by algae as a mechanism for surviving on mine tailings

Abstract: Photosynthetic biofilms successfully colonize the sediments of a mine tailings reservoir (Guanajuato, Mexico) despite the high metal concentrations that are present. To elucidate the mechanisms of biofilm survival despite metal ores, experiments were performed to evaluate the response of seminatural biofilms to Cu, Zn, and a combination of both metals at concentrations observed in the field. The biofilms were composed mostly of the chlorophyte Chlorococcum sp. and the cyanobacterium Phormidium sp., and their response to the two added metals was described by measurements of extracellular polymeric substances (EPS) and in vivo fluorescence. The photosynthetic efficiency and the minimal chlorophyll fluorescence of dark-adapted cells were measured by multiwavelength pulse amplitude-modulated fluorometry. The photosynthetic efficiency of light-adapted cells (phi(PSII)) also was measured. Metal exposure increased the EPS production of biofilms, as visualized with confocal laser-scanning microscopy. Extracellular polymeric substances enhanced the extracellular metal accumulation from the first day of metal exposure. Metals provoked changes in the relative abundance of the dominant taxa because of a species-specific response to the metals when added individually. Metals affected the phi(PSII) less than the total biomass, suggesting ongoing activity of the surviving biofilms. Survival of individual biofilm photosynthetic cells was found to resume from the embedding in the mucilaginous structure, which immobilizes the metals extracellularly. The survival of biofilms under mixed-metal exposure has practical applications in the remediation of mine tailings.

System dynamics approach to assess the sustainability of reclamation of disturbed watersheds

Abstract: The mining of oil sands in northern Alberta leaves behind large open pits, tailings, and overburden piles in which the surface and subsurface hydrology has been completely disrupted. Extensive recl...

Ecosystem Function in Alluvial Tailings after Biosolids and Lime Addition

Abstract: Municipal biosolids and agricultural limestone were incorporated into the surface of alluvial highly acidic, metal-contaminated mine tailings in Leadville, CO, in 1998. Amended sites were seeded and a plant cover was subsequently established. A range of chemical and biological parameters were measured over time to determine if treatment was sufficient to restore ecosystem function. An uncontaminated upstream control (UUC), a contaminated vegetated area (CVA), and soils collected from the tailings deposits before amendment addition were used for comparison. Standard soil extracts showed decreases in extractable Pb, Zn, and Cd in the amended soils. Increased CO 2 evolution, reduced N 2 O, and elevated NO - 3 in the amended tailings indicated an active microbial community. Levels of CO 2 and NO - 3 were elevated in comparison with the CVA and UUC. Ryegrass (Lolium perenne L.) and earthworm (Eisenia foetida) survival and metal uptake values were similar in amended tailings to a laboratory control soil. Ryegrass and worms in unamended tailings died. Field plant diversity was lower in amended areas than in CVA or UUC, with a higher percentage of the vegetative cover consisting of grasses. Small mammal analysis showed a low potential for elevated body Cd and Pb in the amended tailings. A re-entrainment study using fathead minnows (Pimephales promelas) showed no danger for resuspended amended tailings, as survival of fish was similar to the laboratory control. Data suggest that ecosystem function has been restored to the amended tailings, but that these systems are not yet in equilibrium.

Investigation and risk assessment modeling of As and other heavy metals contamination around five abandoned metal mines in Korea.

Abstract: Tailings, agricultural soils, vegetables and groundwater samples were collected from abandoned metal mines (Duckum, Dongil, Dongjung, Myoungbong and Songchun mines) in Korea. Total concentrations of arsenic (As) and heavy metals (Cd, Cu, Pb and Zn) were analyzed to investigate the contamination level. Several digestion methods (Toxicity characteristics leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP), 0.1 N/1 N HCl) and sequential extraction analysis for mine tailings were conducted to examine the potential leachability of As and heavy metals from the tailings. The order of urgent remediation for the studied mines based on the risk assessment and remedial goals was suggested. The Songchun mine tailings were most severely contaminated by As and heavy metals. Total concentrations of As and Pb in the tailings were 38,600–58,700 mg/kg (av. 47,400 mg/kg) and 11,800–16,800 mg/kg (av. 14,600 mg/kg), respectively. Agricultural soils having high As concentrations were found at the all mines. Average concentrations of Cd in the vegetables exceeded the normal value at all mines areas, while As only at the Dongjung, Myoungbong, and Songchun mine area. One groundwater sample each from the Dongil and Myoungbong mines, and 4 groundwater samples from the Songchun mine had values above 10 μg/L of As concentration. The TCLP method revealed that only Pb in the Songchun tailings, 6.49 mg/L, exceeded the regulatory level (5 mg/L). Employing the 1-N HCl digestion method, the concentration of As in the Songchun mine tailings, 4,250 mg/kg, was up to 3,000 times higher than its Korean countermeasure standard. Results from the sequential extraction of As in the tailings showed that the easily releasable fraction in the Myoungbong and Songchun mine tailings was more than 30% and the residual fraction was less than 40%. Based on results showing the exposure health risk employing the hazard quotient and cancer risk of As, Cd and Zn, the Dongil mine needs the most urgent remedial action. The concentration reduction factor (CRF) of As in both soil and groundwater follows the order: Songchun>Dongjung>Dongil>Myoungbong>Duckum mine.

Speciation of mercury and mode of transport from placer gold mine tailings

Abstract: Historic placer gold mining in the Clear Creek tributary to the Sacramento River (Redding, CA) has highly impacted the hydrology and ecology of an important salmonid spawning stream. Restoration of...

Cyanide Treatment: Physical, Chemical, and Biological Processes

Abstract: Several proven and effective chemical, physical, and biological treatment processes have been developed for the removal and recovery of cyanide from mill tailings and process solutions. These treatment processes are well understood and have been used for years at mine sites worldwide. The purpose of this chapter is to provide background information regarding these cyanide treatment processes, including basic chemistry and reagent uses, common areas of application, and treatment performance that can be expected at full-scale. Emphasis is placed on those treatment processes with proven full-scale success, as well as those processes exhibiting significant potential for specific application at mine sites. Coupled with the description of treatment processes are discussions of water management and effluent discharge strategies.

Environmental impact of the former Pb-Zn mining and smelting in East Belgium

Abstract: In the mining district of Plombieres-La Calamine (East Belgium), extensive Pb-Zn mining activities resulted in an important contamination of overbank sediments along the Geul river. Moreover, a huge amount of heavy metals is stored in a dredged mine pond tailing, which is located along the river. In the dredged mine pond tailing sediments, Pb-Zn minerals control the solubility of Zn, Pb and Cd. Although Pb, Zn and Cd display a lower solubility in overbank sediments compared to the mine tailing pond sediments, elevated concentrations of Pb, Zn and Cd are still found in the porewater of the overbank sediments. The considerable dactualT and dpotentialT mobility of Zn, Pb and Cd indicates that the mine pond tailing sediments and the overbank sediments downstream from the mine pond tailing represent a considerable threat for the environment. Besides the chemical remobilisation of metals from the sediments, the erosion of overbank sediments and the reworking of riverbed sediments act as a secondary source of pollution. D 2005 Elsevier B.V. All rights reserved.

The effect of unconfined mine tailings on the geochemistry of soils, sediments and surface waters of the lousal area (Iberian Pyrite Belt, Southern Portugal)

Abstract: The former Lousal mine, on the SW limb of the Lousal anticline, closed in 1988. Today Lousal is a small village, with much evidence of environmental and landscape disturbance. This is largely the legacy of mining and mine tailings dumped around the site, which, in turn, caused soil contamination and acid mine drainage. Particular attention is being given by the Portuguese Government to this sort of problem, bearing in mind the State’s responsibilities for the abandoned mine sites that occur in many parts of the Country. Despite the semiarid climatic conditions of the area, a visual inspection of the mine site indicates that the tailings are affected by considerable water erosion, particularly during large rainfall events. Significant amounts of Cu, Pb, Zn, As, Cd and Hg, occur within the soil collected near the tailing deposits (292– 7013 mg kg � 1 Cu, 871–12 930 mg kg � 1 Pb, 126–7481 mg kg � 1 Zn, 597–6377 mg kg � 1 As, 0� 2–16� 4m g kg � 1 Cd and 1– 130 mg kg � 1 Hg) and in stream sediments downstream of the tailings site (1–1986 mg kg � 1 Cu, 41-5981 mg kg � 1 Pb, 17–1756 mg kg � 1 Zn, 6–1988 mg kg � 1 As and 0� 2–5� 7m g kg � 1 Cd). All the soil samples collected in the tailings deposits exceed the permissible levels. Near the mine site, significant acid mine drainage is associated with the pyritic material and such waters show values of pH ranging from 1� 9t o 2� 9 and concentrations of 9249 to 20 700 mg L � 1 SO4 2� , 959 to 4830 mg L � 1 Fe and 136 to 624 mg L � 1 A1. Meanwhile, the acid effluents and mixed stream waters also carry high contents of SO4 2� , Fe, Al, Cu, Pb, Zn, Cd, and As, generally exceeding the Fresh Water Aquatic Life Acute Criteria. Copyright # 2005 John Wiley & Sons, Ltd.

Iron mineralogy of mine-drainage precipitates as environmental indicators: review of current concepts and a case study from the Sokolov Basin, Czech Republic

Abstract: Mine-drainage waters and associated precipitates from several active and abandoned lignite mines and mine dumps in the Sokolov Basin, northwestern Czech Republic, were sampled and analysed. The data showed considerable variations of effluent composition and pH that can generally be related to differences in the local microenvironments. Temporal changes such as seasonal fluctuations of precipitation, leading to variations of water infiltration through and runoff over mines and mine dumps, were also observed to noticeably affect effluent composition. These variations have led to a wide range of precipitates, the principal constituents of which are generally one or several of the ferric minerals jarosite, schwertmannite, goethite, ferrihydrite and lepidocrocite. The present paper consists of two parts: a short review of the genesis and properties of the named minerals, and a study of mine-drainage precipitates formed under different local conditions in various lignite mines and mine dumps of the Sokolov mining district. We show that variations in mine-drainage precipitate mineralogy, such as the presence or absence of specific ‘key’ minerals, can serve as indicators for factors such as the pH and sulphate concentration, and thus – with certain limitations – for the genetic environment during precipitate formation. Such variations in composition are reflected, among other properties, in the precipitate colour, which can therefore be used for a rapid identification and classification – both in the field and by remote sensing – of regions that are potentially prone to acid mine drainage.

Mineralogical and geochemical characterization of arsenic in an abandoned mine tailings of Korea

Abstract: The mineralogical and chemical characteristics of As solid phases in arsenic-rich mine tailings from the Nakdong As-Bi mine in Korea was investigated. The tailings generated from the ore roasting process contained 4.36% of As whereas the concentration was up to 20.2% in some tailings from the cyanidation process for the Au extraction. Thin indurated layers and other secondary precipitates had formed at the surfaces of the tailings piles and the As contents of the hardened layers varied from 2.87 to 16.0%. Scorodite and iron arsenate (Fe3AsO7) were the primary As-bearing crystalline minerals. Others such as arsenolamprite, bernardite and titanium oxide arsenate were also found. The amorphous As-Fe phases often showed framboidal aggregates and gel type textures with desiccation cracks. Sequential extraction results also showed that 55.7-91.1% of the As in tailings were NH(4)-oxalate extractable As, further confirmed the predominance of amorphous As-Fe solid phases. When the tailings were equilibrated with de-ionized water, the solution exhibited extremely acidic conditions (pH 2.01-3.10) and high concentrations of dissolved As (up to 29.5 mg L(-1)), indicating high potentials for As to be released during rainfall events. The downstream water was affected by drainage from tailings and contained 12.7-522 microg L(-1) of As. The amorphous As-Fe phases in tailings have not entirely been stabilized through the long term natural weathering processes. To remediate the environmental harms they had caused, anthropogenic interventions to stabilize or immobilize As in the tailings pile should be explored.