Showing papers on "Tailings published in 2011"
TL;DR: The changes promoted by the biochar seem to be in favor of its use on mine wastes to help the establishment of a green cover in a phytostabilization process.
438 citations
TL;DR: In this paper, the authors developed a new method for the preparation of high value, environmentally friendly products from tailings Magnetic Fe3O4 nano-powder was synthesized by ultrasonic assisted chemical co-precipitation utilizing high purity iron separated from iron ore tailings by acidic leaching method Magnetite particles with 15nm average diameter were characterized by X-ray diffraction, field-emission scanning electron microscopy and vibrating sample magnetometer.
330 citations
TL;DR: The main acid-producing process is the exposure of pyrite to air and water, which promotes oxidative dissolution, a reaction catalyzed by microbes as discussed by the authors, and current and future mining should plan for the prevention and remediation of these contaminant discharges by the application of hydrogeochemical principles and available technologies.
Abstract: Acid mine waters, often containing toxic concentrations of Fe, Al, Cu, Zn, Cd, Pb, Ni, Co, and Cr, can be produced from the mining of coal and metallic deposits. Values of pH for acid mine waters can range from −3.5 to 5, but even circumneutral (pH ≈ 7) mine waters can have high concentrations of As, Sb, Mo, U, and F. When mine waters are discharged into streams, lakes, and the oceans, serious degradation of water quality and injury to aquatic life can ensue, especially when tailings impoundments break suddenly. The main acid-producing process is the exposure of pyrite to air and water, which promotes oxidative dissolution, a reaction catalyzed by microbes. Current and future mining should plan for the prevention and remediation of these contaminant discharges by the application of hydrogeochemical principles and available technologies, which might include remining and recycling of waste materials.
216 citations
TL;DR: In this paper, a feasibility study is performed on geopolymerization of mine tailings so that they can be recycled and utilized as construction material, and the results show that the Si/Al ratio and the alkalinity have profound effects on the mechanical and micro-structural properties of the mine-tailings-based geopolymers.
203 citations
TL;DR: In this paper, the possibility of making construction bricks by using the hematite tailings from western Hubei province of China was investigated, where the additives of clay and fly ash were added to the raw materials to improve the brick quality.
188 citations
TL;DR: The microbial communities in relation to microbial activities as a function of depth in an active tailings pond routinely treated with gypsum to accelerate densification and Methanogenesis was inhibited in laboratory incubations by nearly 50% suggesting that in situ sulfate reduction can substantially minimize methane emissions.
Abstract: Oil sands tailings ponds receive and store the solid and liquid waste from bitumen extraction and are managed to promote solids densification and water recycling. The ponds are highly stratified du...
187 citations
TL;DR: These studies demonstrating methanogenic biodegradation of longer-chain n-alkanes by microbes native to oil sands tailings may be important for effective management of tailings and greenhouse gas emissions from tailings ponds.
Abstract: Extraction of bitumen from mined oil sands ores produces enormous volumes of tailings that are stored in settling basins (current inventory ≥840 million m3). Our previous studies revealed that certain hydrocarbons (short-chain n-alkanes [C6–C10] and monoaromatics [toluene, o-xylene, m-xylene]) in residual naphtha entrained in the tailings are biodegraded to CH4 by a consortium of microorganisms. Here we show that higher molecular weight n-alkanes (C14, C16, and C18) are also degraded under methanogenic conditions in oil sands tailings, albeit after a lengthy lag (∼180 d) before the onset of methanogenesis. Gas chromatographic analyses showed that the longer-chain n-alkanes each added at ∼400 mg L–1 were completely degraded by the resident microorganisms within ∼440 d at ∼20 °C. 16S rRNA gene sequence analysis of clone libraries implied that the predominant pathway of longer-chain n-alkane metabolism in tailings is through syntrophic oxidation of n-alkanes coupled with CO2 reduction to CH4. These studies d...
180 citations
TL;DR: In this paper, two tailing ponds (Lirio and Gorguel) from an abandoned Pb-Zn mine for a future reclamation were selected, surface samples were taken and analyzed for waste properties and total, extractable by DTPA and water-soluble Pb, Cu, Zn and Cd content.
168 citations
TL;DR: In this article, the authors examined the behavior of the Stava tailings dams in terms of the percentage of silt and sand that composed the soil, and the susceptibility of the dams to liquefaction.
Abstract: Tailings dams can be fragile structures and too often they are subject to liquefaction. The material they are composed of is rather peculiar, having a man-made origin, and their behaviour is still not very well understood. The soil from the Stava tailings dams, structures that were subject to liquefaction in 1985 causing extensive destruction, was investigated in this study as an example of tailings. Two main aspects of their behaviour have been examined: the influence of the percentage of silt and sand that compose the soil on its mechanical behaviour, and the susceptibility to liquefaction, analysing the behaviour within a critical state framework. In this paper it is shown that, as the quantity of silt increases, the slope and intercept of the normal compression line and critical state line at higher pressures decrease until an inversion of behaviour is observed, while at lower stress levels the critical state line changes its position but not its slope. This means that the effect of adding silt on the...
163 citations
TL;DR: In this paper, the authors studied soils and vegetation in three heavily contaminated sites with potential toxic metals and metalloids (Zn, Pb, Cd, As, TI) in the mining district of Les Malines in the Languedoc region (southern France).
Abstract: Mining activities generate spoils and efflu- ents with extremely high metal concentrations of heavy metals that might have adverse effects on ecosystems and human health. Therefore, information on soil and plant metal concentrations is needed to assess the severity of the pollution and develop a strategy for soil reclamation such as phytoremedia- tion. Here, we studied soils and vegetation in three heavily contaminated sites with potential toxic metals and metalloids (Zn, Pb, Cd, As, TI) in the mining district of Les Malines in the Languedoc region (southern France). Extremely high concentrations were found at different places such as the Les Avinieres tailing basins (up to 160,000 mg kg -1 Zn, 90,000 mg kg -1 Pb, 9,700 mg kg -1 of As and 245 mg kg -1 of Tl) near a former furnace. Metal contamination extended several kilometres away from the mine sites probably because of the transport of toxic mining residues by wind and water. Spontaneous vegetation growing on the three mine sites was highly diversified and included 116 plant species. The vegetation cover consisted of species also found in non-contaminated soils, some of which have been shown to be metal- tolerant ecotypes (Festuca arvernensis, Koeleria vallesiana and Armeria arenaria) and several Zn, Cd and Tl hyperaccumulators such as Anthyllis vulneraria, Thlaspi caerulescens, Iberis intermedia and Silene latifolia. This latter species was highlighted as a new thallium hyperaccumulator, accumulating nearly 1,500 mg kg -1 . These species represent a patrimonial interest for their potential use for the phytoremediation of toxic metal-polluted areas.
139 citations
TL;DR: The tendency of mine wastes to produce acid or neutral drainage containing potentially toxic metals generally reflects the ratio of primary sulfide to carbonate minerals and the trace element concentrations inherited from the ore deposit, as well as any ore processing that may have created new compounds as mentioned in this paper.
Abstract: Large volumes of waste rock and mine tailings are stored at mine sites. Predicting the environmental impact of these wastes requires an understanding of mineral–water interaction and the characterization of the solid materials at the microscopic scale. The tendency of mine wastes to produce acid or neutral drainage containing potentially toxic metals generally reflects the ratio of primary sulfide to carbonate minerals and the trace element concentrations inherited from the ore deposit, as well as any ore processing that may have created new compounds. Whether potentially toxic elements are released to surface water, groundwater, or bodily fluids (in the case of ingestion or inhalation) depends on the host mineral and the possibility of sequestration by secondary minerals.
TL;DR: The size-fractionated chemical characterization of atmospheric aerosols sampled over a period of a year near an active mining and smelting site in Arizona show that arsenic and lead concentrations follow a bimodal distribution, with maxima centered at approximately 0.3 and 7.0 μm diameter, and it is hypothesize that the sub-micron arsenic andLead are the product of condensation and coagulation of Smelting vapors.
Abstract: Mining operations are potential sources of airborne metal and metalloid contaminants through both direct smelter emissions and wind erosion of mine tailings. The warmer, drier conditions predicted for the Southwestern US by climate models may make contaminated atmospheric dust and aerosols increasingly important, with potential deleterious effects on human health and ecology. Fine particulates such as those resulting from smelting operations may disperse more readily into the environment than coarser tailings dust. Fine particles also penetrate more deeply into the human respiratory system, and may become more bioavailable due to their high specific surface area. In this work, we report the size-fractionated chemical characterization of atmospheric aerosols sampled over a period of a year near an active mining and smelting site in Arizona. Aerosols were characterized with a 10-stage (0.054 to 18 μm aerodynamic diameter) multiple orifice uniform deposit impactor (MOUDI), a scanning mobility particle sizer (SMPS), and a total suspended particulate (TSP) collector. The MOUDI results show that arsenic and lead concentrations follow a bimodal distribution, with maxima centered at approximately 0.3 and 7.0 μm diameter. We hypothesize that the sub-micron arsenic and lead are the product of condensation and coagulation of smelting vapors. In the coarse size, contaminants are thought to originate as aeolian dust from mine tailings and other sources. Observation of ultrafine particle number concentration (SMPS) show the highest readings when the wind comes from the general direction of the smelting operations site.
TL;DR: In this article, a seven-step sequential extraction procedure was used to investigate the mobility and retention behaviour of Al, Fe, Mn, Cu, Zn, Pb, Cr, Co, Ni, Mo, Cd, Bi, Sn, W, Ag, As and U in specific physical-chemical and mineral phases in mine tailings and soils in the surroundings of the abandoned Ervedosa mine.
TL;DR: Negative impacts in the diatom communities growing at different sites along a strong metal pollution gradient were shown through Canonical Correspondence Analysis: in the sites influenced by Acid Mine Drainage (AMD), the dominant taxon was Achnanthidium minutissimum, however, Pinnularia acoricola was the dominant species when the environmental conditions were extremely adverse.
TL;DR: Based on the inherent tolerance ability of J. curcas in existing adverse environmental conditions without liming, it could be used as a suitable candidate for phytostabilization in acid mine tailings.
Abstract: Greenhouse pot experiments were conducted to determine the growth response, metal tolerance, and phytostabilization potential of Jatropha curcas L The plants were grown on different degrees of multi-metal contaminated acid mine soils (T0, control; T1, moderately and T2, highly contaminated soils) with or without limestone amendments. The order of metal accumulation in J. curcas was roots>stems>leaves. The higher tolerance index (>90%) with no phytotoxic symptoms and growth reduction in T1 showed that this plant has the ability to tolerate polymetallic acid mine tailings. Further, various enzymatic and non-enzymatic antioxidants also actively involved in metal defense mechanism in J. curcas. On the other hand, to alleviate the predominant phytoavailable toxic metals such as Al, Cu, and Pb, different rates (0.1, 0.25, 0.50, and 1%) of limestone amendments were added in both T1 and T2 soils. The growth performance of J. curcas was improved due to the increase in soil pH and decrease in phytoavailable soil A1 (95%), Zn (approximately 75%), and Cu (approximately 65%) contents at 0.50% of lime addition. Based on the inherent tolerance ability of J. curcas in existing adverse environmental conditions without liming, it could be used as a suitable candidate for phytostabilization in acid mine tailings.
TL;DR: Whether arbuscular mycorrhizal fungi (AMF) can help support plant growth in tailings at a reduced compost concentration is explored and changes in the rhizosphere microbial community structure of the native plant Prosopis juliflora are investigated.
TL;DR: 2-Line ferrihydrite, a form of iron in uranium mine tailings, is a dominant adsorbent for elements of concern (EOC), such as arsenic, and arsenic was found to retard ferriHydrite dissolution and transformation as well as goethite formation.
Abstract: 2-Line ferrihydrite, a form of iron in uranium mine tailings, is a dominant adsorbent for elements of concern (EOC), such as arsenic. As ferrihydrite is unstable under oxic conditions and can undergo dissolution and subsequent transformation to hematite and goethite over time, the impact of transformation on the long-term stability of EOC within tailings is of importance from an environmental standpoint. Here, studies were undertaken to assess the rate of 2-line ferrihydrite transformation at varying As/Fe ratios (0.500-0.010) to simulate tailings conditions at the Deilmann Tailings Management Facility of Cameco Corporation, Canada. Kinetics were evaluated under relevant physical (~1 °C) and chemical conditions (pH ~10). As the As/Fe ratio increased from 0.010 to 0.018, the rate of ferrihydrite transformation decreased by 2 orders of magnitude. No transformation of ferrihydrite was observed at higher As/Fe ratios (0.050, 0.100, and 0.500). Arsenic was found to retard ferrihydrite dissolution and transformation as well as goethite formation.
TL;DR: Tailings storage facilities could be redesigned to promote CO₂ sequestration by directing leachate waters from tailings piles into specially designed ponds where carbonate precipitation would be mediated by both chemical and biological processes, thereby storing carbon in stable carbonate minerals and potentially valuable biomass.
Abstract: Ultramafic mine tailings from the Diavik Diamond Mine, Canada and the Mount Keith Nickel Mine, Western Australia are valuable feedstocks for sequestering CO2 via mineral carbonation. In microcosm experiments, tailings were leached using various dilute acids to produce subsaline solutions at circumneutral pH that were inoculated with a phototrophic consortium that is able to induce carbonate precipitation. Geochemical modeling of the experimental solutions indicates that up to 2.5% and 16.7% of the annual emissions for Diavik and Mount Keith mines, respectively, could be sequestered as carbonate minerals and phototrophic biomass. CO2 sequestration rates are mainly limited by cation availability and the uptake of CO2. Abundant carbonate mineral precipitation occurred when heterotrophic oxidation of acetate acted as an alternative pathway for CO2 delivery. These experiments highlight the importance of heterotrophy in producing sufficient DIC concentrations while phototrophy causes alkalinization of waters an...
TL;DR: A technique with coal-based direct reduction followed by magnetic separation is presented in this study for recovering and reusing iron otherwise wasted in vanadium tailings.
TL;DR: In this article, a detailed mineralogical, geochemical, and microbiological investigation of two tailing impoundments near the town of Pezinok, Slovakia is presented. But the primary objective of this study was the mineralogy that formed in the impoundment after the deposition of the tailings (so-called tertiary minerals), which are present as grains and as rims on primary ore minerals.
Abstract: The mineralogical composition of mining wastes deposited in voluminous tailing impoundments around the world is the key factor that controls retention and release of pollutants. Here we report a detailed mineralogical, geochemical, and microbiological investigation of two tailing impoundments near the town of Pezinok, Slovakia. The primary objective of this study was the mineralogy that formed in the impoundment after the deposition of the tailings (so-called tertiary minerals). Tertiary minerals include oxyhydroxides of Fe, Sb, As, Ca and are present as grains and as rims on primary ore minerals. X-ray microdiffraction data show that the iron oxyhydroxides with abundant As are X-ray amorphous. The limiting (lowest) Fe/As (wt/wt%) ratio in this material is 1.5; beyond this ratio, the hydrous ferric oxide does not retain arsenic. The grains with less As and little to moderate amounts of Sb are goethite; the grains where Sb dominates over Fe are poorly crystalline tripuhyite (FeSbO4). Even the most heavily contaminated samples (up to 29 wt% As2O5) are populated with diverse communities of microorganisms including typical arsenic-resistant heterotrophic species as well as iron reducers and sulfur oxidizers. Several recovered clones cluster within phylogenetic groups that are solely based on environmental sequences and do not contain a single cultivated species, thus calling for more work on such extreme environments.
TL;DR: In this paper, the effect of preconditioning coal tailings with varying flocculants and dosages on filtration kinetics and the resultant moisture content of the filter cake was investigated.
TL;DR: The results show that the PF has advantage over the hyperaccumulator in reflecting the removal capabilities of a plant for a target element, and is more adequate for assessing the potential of a plants to be used in phytoremediation than conventional method.
Abstract: The concentrations of uranium, thorium, barium, nickel, strontium and lead in the samples of the tailings and plant species collected from a uranium mill tailings repository in South China were analyzed. Then, the removal capability of a plant for a target element was assessed. It was found that Phragmites australis had the greatest removal capabilities for uranium (820 μg), thorium (103 μg) and lead (1,870 μg). Miscanthus floridulus had the greatest removal capabilities for barium (3,730 μg) and nickel (667 μg), and Parthenocissus quinquefolia had the greatest removal capability for strontium (3,920 μg). In this study, a novel coefficient, termed as phytoremediation factor (PF), was proposed, for the first time, to assess the potential of a plant to be used in phytoremediation of a target element contaminated soil. Phragmites australis has the highest PFs for uranium (16.6), thorium (8.68), barium (10.0) and lead (10.5). Miscanthus floridulus has the highest PF for Ni (25.0). Broussonetia papyrifera and Parthenocissus quinquefolia have the relatively high PFs for strontium (28.1 and 25.4, respectively). On the basis of the definition for a hyperaccumulator, only Cyperus iria and Parthenocissus quinquefolia satisfied the criteria for hyperaccumulator of uranium (36.4 μg/g) and strontium (190 μg/g), and could be the candidates for phytoremediation of uranium and strontium contaminated soils. The results show that the PF has advantage over the hyperaccumulator in reflecting the removal capabilities of a plant for a target element, and is more adequate for assessing the potential of a plant to be used in phytoremediation than conventional method.
TL;DR: A greenhouse pot experiment was conducted to evaluate the potential of selected woody plants for revegetation in copper (Cu) and lead/zinc (Pb/Zn) mine tailing areas, suggesting that A. fruticosa and S. cannabina, which have the highest tolerance and biomass production, respectively, demonstrated the potential for tailings revegetations in southern China.
Abstract: A greenhouse pot experiment was conducted to evaluate the potential of selected woody plants for revegetation in copper (Cu) and lead/zinc (Pb/Zn) mine tailing areas. Five woody species (Amorpha fruticosa Linn, Vitex trifolia Linn. var. simplicifolia Cham, Glochidion puberum (Linn.) Hutch, Broussonetia papyrifera, and Styrax tonkinensis) and one herbaceous species (Sesbania cannabina Pers) were planted in Cu and Pb/Zn tailings to assess their growth, root morphology, nutrition uptake, metal accumulation, and translocation in plants. Amorpha fruticosa maintained normal growth, while the other species demonstrated stress related growth and root development. Sesbania cannabina showed the highest biomass among the plants, although it decreased by 30% in Cu tailings and 40% in Pb/Zn tailings. Calculated tolerance index (TI) values suggested that A. fruticosa, an N-fixing shrub, was the most tolerant species to both tailings (TI values 0.92-1.01), while S. cannabina had a moderate TI of 0.65-0.81 and B. papyrifera was the most sensitive species, especially to Pb/Zn tailings (TI values 0.15-0.19). Despite the high concentrations of heavy metals in the mine tailings and plants roots, only a small transfer of these elements to the aboveground parts of the woody plants was evident from the low translocation factor (TF) values. Among the woody plants, V. trifolia var. simplicifolia had the highest TF values for Zn (1.32), Cu (0.78), and Pb/Zn (0.78). The results suggested that A. fruticosa and S. cannabina, which have the highest tolerance and biomass production, respectively, demonstrated the potential for tailings revegetation in southern China.
TL;DR: In this article, the authors describe a recently completed study conducted at seven gold processing centers in Portovelo-Zaruma, Southern Ecuador, which involved consultation with local miners to understand the behaviour of mercury (with a focus on mercury loss) in artisanal gold mining operations through the evaluation of two cyanidation processes (Merrill-Crowe and Carbon-in-pulp), using a participatory approach.
TL;DR: In this paper, a laboratory physical model test has been performed to evaluate the structural stability of a new tailings impoundment, where the tailings particle composition and distribution below a beach, the change of phreatic surface of the dam, and the engineering properties of tailings of dam profiles have been measured.
TL;DR: In this article, the unsaturated hydraulic properties (water retention curve (WRC), air entry value (AEV), residual water content, unsaturated hydraulics conductivity) of gelfill (GF) are investigated.
TL;DR: Radiocarbon and stable carbon and oxygen isotopes are used to assess the ability of mine tailings to trap and store modern CO(2) within secondary carbonate minerals in the arid, subarctic climate at Diavik.
Abstract: The mineral waste from some mines has the capacity to trap and store CO2 within secondary carbonate minerals via the process of silicate weathering. Nesquehonite [MgCO3·3H2O] forms by weathering of Mg-silicate minerals in kimberlitic mine tailings at the Diavik Diamond Mine, Northwest Territories, Canada. Less abundant Na- and Ca-carbonate minerals precipitate from sewage treatment effluent deposited in the tailings storage facility. Radiocarbon and stable carbon and oxygen isotopes are used to assess the ability of mine tailings to trap and store modern CO2 within these minerals in the arid, subarctic climate at Diavik. Stable isotopic data cannot always uniquely identify the source of carbon stored within minerals in this setting; however, radiocarbon isotopic data provide a reliable quantitative estimate for sequestration of modern carbon. At least 89% of the carbon trapped within secondary carbonate minerals at Diavik is derived from a modern source, either by direct uptake of atmospheric CO2 or indir...
TL;DR: These findings suggest tailings wetlands become less toxic with age, and that these amphibians will be able to complete their life cycle in tailing wetlands that have sufficiently detoxified with age.
Journal Article•
TL;DR: Quantitative PCR (and statistical analyses) revealed that, overall, copy number of nifH sequences increased with progressing succession and correlated with changes in physiochemical properties and the recorded nitrogenase activities of the tailings.