Showing papers on "Tailings published in 2000"

An Archaeal Iron-Oxidizing Extreme Acidophile Important in Acid Mine Drainage

Abstract: A new species of Archaea grows at pH ∼0.5 and ∼40°C in slime streamers and attached to pyrite surfaces at a sulfide ore body, Iron Mountain, California. This iron-oxidizing Archaeon is capable of growth at pH 0. This species represents a dominant prokaryote in the environment studied (slimes and sediments) and constituted up to 85% of the microbial community when solution concentrations were high (conductivity of 100 to 160 millisiemens per centimeter). The presence of this and other closely related Thermoplasmales suggests that these acidophiles are important contributors to acid mine drainage and may substantially impact iron and sulfur cycles.

Methanogens and sulfate-reducing bacteria in oil sands fine tailings waste

Abstract: In the past decade, the large tailings pond (Mildred Lake Settling Basin) on the Syncrude Canada Ltd. lease near Fort McMurray, Alta., has gone methanogenic. Currently, about 60%-80% of the flux of...

Diatom communities as indicators of environmental stress in the Guadiamar River, S-W. Spain, following a major mine tailings spill

Abstract: An accident in a mine tailings dam caused the outflowof mud and water rich in heavy metals in April 1998that flooded the Guadiamar River and its floodplain,in the vicinity of Donana National Park Theimpact on the periphytic communities was evaluated byanalyzing the evolution of the diatom communitiesafter seven (November 1998) and fourteen months (June1999) of the accident The comparison between thereference and affected sites showed a shift from adiatom community dominated by Fragilariaconstruens, Achnanthes minutisssima and Amphora pediculus to another dominated by Nitzschia palea and Gomphonema parvulum Thevalues for Shannon-Wiener diversity strongly decreasedin the affected area; changes between survey periodsfailed to show a marked recovery However, evennesswas slightly higher for the June 1999 period,suggesting a slight improvement in the diatomcommunity Diatom indices (IPS-IDG, Descy, CEE,Lange-Bertalot) were applied to the data Values forthese also showed a marked decrease in water qualityat sites closest to the mine tailings spill, as wellas a progressive recovery downstream Correlationanalyses between the diatom descriptors and theenvironmental variables confirmed that heavy metals inthe water and sediment had a marked and lasting effecton the diatom communities of the Guadiamar Otherpollution events (eg `alpechin' sewage) probablyhindered recovery of the periphytic communities

Recovery Exploitation of iron ore tailing for the development of ceramic tiles

Abstract: India ranks as the sixth largest producer of iron ore in the world. The current practice of washing iron ore in India generates as high as 18 million tonnes of tailings per year. These tailings are stored in massive ponds and pose environmental hazards. Safe disposal or utilisation of these materials thus remains a challenging task for the iron ore industry in India. The present paper describes a new development in managing these tailings by converting them into value added products such as ceramic floor and wall tiles for building application. These tiles have high strength and hardness compared to conventional tiles and conform to most of the EN standards. Energy economy and lower production costs are some other benefits. (C) 2000 Elsevier Science Ltd. All rights reserved.

Arsenic Speciation: Involvement in Evaluation of Environmental Impact Caused by Mine Wastes

Abstract: Since large areas have been contaminated by arsenic-rich industrial and mining by-products in several countries, knowledge of arsenic (As) behavior in soils and water is of major concern for reclamation of polluted sites and evaluation of environmental risk. Chemi's tailings (France) contains average concentrations up to 7,000 mg kg{sup {minus}1} As and was listed by the authority as an important potentially pollutant site. Because As speciation determines its mobility, it was investigated in surface and ground waters of the site and a study of the solid As-bearing phase was performed on suspended particulate material (SPM). Results of sequential extraction, carried out on the SPM collected in drainage waters, show that most of total extracted As (78%) and Fe (77%) is bound to an iron hydrous oxide phase, which was determined to be lepidocrocite ({gamma}-FeOOH) by x-ray diffraction and infrared spectrometry. Particulate material was >220 times more concentrated than dissolved As. Conditions for the stability of dissolved (<0.45 {micro}m) arsenite [As(III)] and arsenate [As(V)] are discussed on the basis of thermodynamical data and field measurements of pH and redox potentials. The theoretical stability of As(V) corresponds to a large association between As and particulate material, and large amounts of the metalloidmore » are released in solution when As-rich particles come from oxidized ground waters to moderately reduced conditions. These results are important for evaluating, modeling, and rehabilitating As-polluted sites.« less

The environmental impact of gold mine tailings footprints in the Johannesburg region, South Africa

Abstract: Gold mining in South Africa resulted in vast volumes of tailings, which have been deposited in impoundments. Poor management of most of the tailings dams resulted in the escape of seepage, adversely affecting soils and water quality. Some tailings dams have been partially or completely reclaimed leaving contaminated footprints. These zones pose a serious threat to the underlying dolomitic aquifers. In this study, the footprints of seven selected sites situated near Johannesburg have been investigated. It was found that the topsoil is highly acidified and only a minor portion of contaminants is bioavailable. However, phytotoxic contaminants such as Co, Ni and Zn could complicate rehabilitation measures as they limit the soil function. In addition, soil samples contain trace element concentrations, which often exceed background concentrations in soils. As a result, the depletion of buffer minerals and the subsequent acidification could result in the long-term remobilization of large quantities of contaminants into the groundwater. Soil management measures such as liming are required to prevent the contaminant migration from the topsoil into the subsoil and groundwater as well as to provide suitable recultivation conditions to enable future land use.

Mercury Speciation in Drainage from the New Idria Mercury Mine, California

Abstract: Little is known about the amount and form of mercury released from inoperative mercury mines in the western United States. To address this, we measured mercury concentrations and speciation in water impacted by the New Idria mine. Total unfiltered mercury concentrations (UHgT) in acid mine drainage (AMD) (5.2 to 41 ng/L) were comparable to concentrations upstream from the mine (4.2 to 13 ng/L). We measured substantially higher UHgT concentrations (2900 to 12 400 ng/L) in water 1.2 km downstream from the AMD input and estimate that the creek transports a baseline flux of 1.5 kg of Hg/yr from the mine site. We hypothesize that tailings are the primary source of mercury to this creek. We attribute the decrease in UHgT along a downstream transect to Hg(II) scavenging by iron oxyhydroxide particles that precipitate and settle out of the water. Likewise, dissolved gaseous mercury concentrations decreased with increasing distance from the mine (2.8 ng/L at 1.2 km; 0.56 ng/L at 7.5 km). We regard abiotic atmosphe...

Heavy metal coprecipitation with hydrozincite [Zn(5)(CO(3))(2)(OH)(6)] from mine waters caused by photosynthetic microorganisms.

Abstract: An iron-poor stream of nearly neutral pH polluted by mine tailings has been investigated for a natural phenomenon responsible for the polishing of heavy metals in mine wastewaters. A white mineralized mat, which was determined to be hydrozincite [Zn5(CO3)2(OH)6] by X-ray diffraction analysis, was observed in the stream sediments mainly in spring. The precipitate shows a total organic matter residue of 10% dry weight and contains high concentrations of Pb, Cd, Ni, Cu, and other metals. Scanning electron microscopy analysis suggests that hydrozincite is mainly of biological origin. Dormant photosynthetic microorganisms have been retrieved from 1-year-old dry hydrozincite. The autofluorescent microorganisms were imaged by a scanning confocal laser microscope. A photosynthetic filamentous bacterium, classified as Scytonema sp. strain ING-1, was found associated with microalga Chlorella sp. strain SA1. This microbial community is responsible for the natural polishing of heavy metals in the water stream by coprecipitation with hydrozincite. Abandoned mines present a high environmental hazard in all countries today. In several parts of the world where mining activities have shut down, the problem of the control and reclamation of polluted areas for new activities arises. The polishing of metals from a mining area is a difficult task. The transformation of metals into harmless species or their removal in a suitable recycled mineral form such as carbonates (1, 15) is a possible solution for the remediation of a mining area. Therefore, research in this field continues, with the isolation of new strains with more-successful mechanisms for the reduction of metal toxicity. At Ingurtosu (southwestern Sardinia, Italy) lead and zinc sulfide ore deposits were mined until 1968 and tailings were deposited along the Rio Naracauli creek. The MontevecchioIngurtosu deposit consists of galena-sphalerite veins in a quartz gangue containing iron, calcium, and magnesium carbonate minerals. Pyrite, chalcopyrite, barite, cerussite, and anglesite are the most commonly associated minerals (22). Previous studies in this area have shown that waters are highly polluted by heavy metals, in spite of their near-neutral pH (4‐6, 30).

Reproductive, immune, and physiological end points in tree swallows on reclaimed oil sands mine sites

Abstract: Wild nestling tree swallows (Tachycineta bicolor) inhabiting reclaimed wetlands receiving tailings or water from mine tailings ponds on oil sands mine sites were the subjects in a multiyear study to determine the ecological viability of these areas. Spanning two field seasons, immune function, reproductive performance (clutch size and mass, hatching success), nestling growth and survival, and diet of tree swallows were examined on six wetlands. One aspect of immune function, the T-lymphocyte proliferative response, was assessed in vivo using a phytohemagglutinin skin test. Hepatic ethoxyresorufin-O -deethylase (EROD) activityprovided a biomarker of exposure to oil sands contaminants in the tree swallow nestlings. Results show that there were no differences among reclaimed wetland sites for tree swallow reproductive success, nestling growth rate, and immune response that could be attributed to tailings or tailings pond water additions. Increased EROD activity confirmed the presence of xenobiotics in the diets of nestlings from two sites, while the main reference site was relatively free of EROD-inducing compounds. Dietary analyses showed that 84% of the food items of the tree swallow nestlings were of aquatic origin, likely from the local wetlands, and thus would be expected to provide a good reflection of biological effects of any mining-related contaminants accumulating through the food chain.

Crushed rocks and mine tailings applied as K fertilizers on grassland

Abstract: Crushed rocks and mine tailings containing biotite, K-feldspar and nepheline as K-bearing minerals were applied as K fertilizers in a series of 15 grassland field trials. A treatment with KCl as K-source outyielded treatments with rock based fertilizers in the first and the second experimental year. In the third and last year of the study when no K fertilizers were supplied, previously added carbonatite and biotite concentrate supported grass growth as much as previously added KCl did. Although it is concluded that a substantial part of the K bound in biotite and/or nepheline in crushed carbonatites, biotite concentrate and epidote schists is plant available, these rock/mineral products weathered too slowly to replenish the native pool of plant available K within a three year period with five harvests. The K bound in K-feldspar seemed to be nearly unavailable for the grass plants.

Influence of Reduction Reactions and Solid-Phase Composition on Porewater Concentrations of Arsenic

Abstract: An increasing amount of attention is being focused on the effects of arsenic on health and the factors that control arsenic mobility in groundwater. The release and transport of arsenic below the water table in the current tailings impoundment at Campbell Mine in Balmertown, ON, Canada, are controlled by the reduction of ferric oxide phases within the saturated tailings. The activity of chemolithotrophic bacteria is indicated by enriched δ34S−SO4 ratios, high alkalinity, depleted δ13C−CO3 ratios, and low SO4 concentrations, all of which are consistent with bacterially mediated Fe and SO4 reduction. The concentrations of Fe and As in the tailings porewater increase with depth. This increase is attributed to the bacterially mediated reduction of As-rich hematite and maghemite. The maximum concentrations of Fe and As are 20 and 100 mg/L, respectively. At the bottom of the impoundment, As concentrations decrease sharply to 0.3 mg/L. This decrease in concentration is attributed to reprecipitation of the As as ...

Revegetation of Pb/Zn Mine Tailings, Guangdong Province, China

Abstract: The Lechang lead/zinc mine is located in the north part of Guangdong Province, southern China. The tailings residue from the extraction of lead/zinc ores was permanently stored in tailings ponds, which required revegetation to reduce the environmental impact. A field study was, therefore, conducted to evaluate the effects of different ameliorants, including: (1) pig manure (PM); (2) mushroom compost (MC); (3) burnt coal residue (BC); (4) fly ash (FA); and (5) surface soil on the growth of Agropyron elongatum (tall wheat grass), Cynodon dactylon (Bermuda grass), Lolium multiflorum (Italian ryegrass), and Trifolium repens (clover) in the tailings residue. The results from the core profiles indicated that adding FA (10 cm) or BC (15 cm) as a barrier layer between the cover soil and the tailings could increase pH, compared to the treatment with soil only. C. dactylon grew well and had a high cover (90‐100%) in all the treatment plots except the control plots without any amendment. A. elongatum and L. multiflorum had a higher cover when grown in plots covered with a barrier layer using FA or BC (both with surface soil), than those grown in plots covered with surface soil only. Treatment plots receiving a thicker soil cover (30 cm) had a better dry weight yield than those with a thinner soil cover (15 cm), regardless of the barrier layer. The results from this study indicate that the use of either 15 cm BC or 10 cm FA as a barrier layer with surface soil, or the use of 38 tonnes PM/ha and 6 cm MC, were effective for the revegetation of Pb/Zn mine tailings. C. dactylon was the best species among the four species used for revegetation.

Post-mining landform evolution modelling: 2. Effects of vegetation and surface ripping.

Abstract: Computer simulations of the topographic evolution of the proposed post-mining rehabilitated landform for the ERA Ranger Mine, showed that for the unvegetated and unripped case, the landform at 1000 years would be dissected by localized erosion valleys (maximum depth = 7·6 m) with fans (maximum depth = 14·8 m) at the outlet of the valleys. Valley form simulated by SIBERIA has been recognized in nature. This indicates that SIBERIA models natural processes efficiently. For the vegetated and ripped case, reduced valley development (maximum 1000 year depth = 2·4m) and deposition (maximum 1000 year depth = 4·8m) occurred in similar locations as for the unvegetated and unripped case (i.e. on steep batter slopes and in the central depression areas of the landform). For the vegetated and ripped condition, simulated maximum valley depth in the capping over the tailings containment structure was c. 2·2 m. By modelling valley incision, decisions can be made on the depth of tailings cover required to prevent tailings from being exposed to the environment within a certain time frame. A reduction in thickness of 1 m of capping material over tailings equates to c. 1 000 000 Mm3 over a 1 km2 tailings dam area. This represents a saving of c. $1 500 000 in earthworks alone. Incorporation of SIBERIA simulations in the design process may result in cost reduction while improving confidence in environmental protection mechanisms. Copyright 2000 © Environmental Research Institute of the Supervising Scientist, Commonwealth of Australia.

Copper bioavailability and amelioration of toxicity in Macquarie Harbour, Tasmania, Australia

Abstract: The 100-year operation of the Mount Lyell Mining and Railway Company Limited's copper mine in Queenstown, Australia, has resulted in the deposition of over 100 million cubic metres of mine tailings, smelter slag and topsoil into the King River and Macquarie Harbour. A preliminary risk assessment, together with chemical mea- surements of dissolved copper, ASV-labile copper, copper complexing capacity and resin-adsorbed copper, sug- gested that copper in mid-salinity harbour waters was potentially bioavailable. However, toxicity tests based on inhibition of microalgal (Nitzschia closterium) growth showed that copper in these waters was not toxic, even though labile copper concentrations (6-24 mg L -1 ) exceeded the concentration of lowest observable effect for algae of 5 mg L -1 . Measurements of intracellular and membrane-bound copper confirmed that cell division was not affected because copper was not taken up intracellularly. Amelioration of copper toxicity was due to binding of dis- solved organic matter and/or other metals at the cell membrane, preventing copper binding and uptake. An under- standing of the mechanism of copper toxicity and its amelioration is vital to assessing various clean-up options for the harbour.

Microbiological Pyrite Oxidation in a Mine Tailings Heap and Its Relevance to the Death of Vegetation

Abstract: The oxidation of pyrite in a mine tailings heap in Romania was studied to clarify the contribution of acid drainage to the death of vegetation on the eastern slope of the tailings. Where vegetation died, pyrite oxidation was detected as deep as 1 m, as indicated by the brownish color of the samples. At these sites Thiobacillus ferrooxidans-like bacteria were present with cell counts of 10 3g and Thiobacillus thiooxidans-like bacteria occurred with cell counts of 10 g. At the western slope, where vegetation thrived, cell counts of < 10 g were measured. Correspondingly, leaching activity and concentrations of pyrite oxidation products such as sulfate and elemental sulfur were markedly higher on the eastern slope than on the western slope. These differences were mainly a result of the high acid neutralization potential in the material from the western slope, which kept the pH in a neutral range allowing for plant growth. In contrast, on the eastern slope with its low acid neutralization potential, the pH ...