The Experts below are selected from a list of 8505 Experts worldwide ranked by ideXlab platform
Youngsuk Song - One of the best experts on this subject based on the ideXlab platform.
-
analyses on variations in the unsaturated characteristics of a mine Waste Dump slope during rainfall
Environmental Earth Sciences, 2016Co-Authors: Youngsuk Song, Yongchan Cho, Seongwon HongAbstract:Field measurement units and a system were constructed and installed in a Waste-Dump slope at the Imgi mine to investigate and analyze the variations in the unsaturated characteristics of the soil. The field instrumentation system was composed of a data acquisition system, a solar system, and measuring sensors. The rainfall, matric suction, and volumetric water contents were continuously measured from the units in the instrumented site and analyzed with the soil water characteristic curve (SWCC) estimated from laboratory experiments. The variations in matric suction and volumetric water content were primarily affected by the rainfall intensity. At the surface of the slope, the largest increase and decrease in the changes in matric suction and volumetric water content were observed during the wetting and drying processes, respectively. The matric suction and volumetric water content measured from the instrumented area were compared with the SWCCs obtained from the laboratory test, and the measured data were located between the drying and wetting paths. The drying and wetting paths obtained from the laboratory test are regarded as primary drying and wetting curves, respectively. Therefore, the measured data can be defined as scanning curves, which are located between primary drying and wetting curves. The variations in matric suction according to volumetric water content were dependent on depth, and a wide range of variations was observed at shallow depths. It was confirmed that the unsaturated soil near the ground surface has the sensitive reaction induced by the infiltration and evaporation in nature.
-
deformation measurements and a stability analysis of the slope at a coal mine Waste Dump
Ecological Engineering, 2014Co-Authors: Yongchan Cho, Youngsuk SongAbstract:Abstract This study surveyed and investigated the deformation of the coal Waste Dump slope and the natural ground slope under the Waste Dump at Dogye village in Samcheock city, Gangwon Province, Korea. Multiple sets of south-north tension cracks were observed at the crest of the coal Waste Dump slope. These cracks were greater than 100 m in length, and the resulting drop head averaged 1.0–1.5 m. To investigate the behaviors of the Waste Dump slope and the natural slope under the Waste Dump, wire sensors and a rain gauge were installed at the crest of the Waste Dump slope, and inclinometers were installed in the natural slope of the ground under the Waste Dump. According to the monitoring results, the deformation at the crest of the Waste Dump slope steadily increased and then converged over time due to the effect of the infiltration of rain into the ground after rainfall. In addition, the horizontal deformation of the natural slope under the Waste Dump was affected by the accumulated precipitation. The basis of this effect is that the rate of increase of the maximum horizontal deformation tends to show increasing or convergent behavior according to the precipitation. The slope stability analysis showed that the safety factor of the natural slope before the discharge of the Waste was 2.14. Meanwhile, the safety factor of the Waste Dump slope, including the natural slope in the dry season was 1.66 and the safety factor in the rainy season was 0.98. The natural slope before the discharge of the Waste and the coal Waste slope, including the natural slope remained stable during the dry season but became unstable during the rainy season, especially when the ground water level in the Waste Dump slope becomes rising as a result of infiltration by rainwater. The Waste Dump slope and the natural slope under the Waste Dump experienced deformation due to the increasing weight placed on the Waste Dump by the infiltration resulting from rainfall.
Martin Mihaljevic - One of the best experts on this subject based on the ideXlab platform.
-
arsenic mineralogy and mobility in the arsenic rich historical mine Waste Dump
Science of The Total Environment, 2015Co-Authors: Michal Filippi, Petr Drahota, Vladimir Machovic, Vlasta Bohmova, Martin MihaljevicAbstract:A more than 250 year-old mine Dump was studied to document the products of long-term arsenopyrite oxidation under natural conditions in a coarse-grained mine Waste Dump and to evaluate the environmental hazards associated with this material. Using complementary mineralogical and chemical approaches (SEM/EDS/WDS, XRD, micro-Raman spectroscopy, pore water analysis, chemical extraction techniques and thermodynamic PHREEQC-2 modeling), we documented the mineralogical/geochemical characteristics of the Dumped arsenopyrite-rich material and environmental stability of the newly formed secondary minerals. A distinct mineralogical zonation was found (listed based on the distance from the decomposed arsenopyrite): scorodite (locally associated with native sulfur pseudomorphs) plus amorphous ferric arsenate (AFA/pitticite), kaňkite, As-bearing ferric (hydr)oxides and jarosite. Ferric arsenates and ferric (hydr)oxides were found to dissolve and again precipitate from downward migrating As-rich solutions cementing rock fragments. Acidic pore water (pH3.8) has elevated concentrations of As with an average value of about 2.9 mg L(-1). Aqueous As is highly correlated with pH (R2=0.97, p<0.001) indicating that incongruent dissolution of ferric arsenates controls dissolved As well as the pH of the percolating Waste solution. Arsenic released from the dissolution of ferric arsenates into the pore water is, however, trapped by latter and lower-down precipitating jarosite and especially ferric (hydr)oxides. The efficiency of As sequestration by ferric (hydr)oxides in the Waste Dump and underlying soil has been found to be very effective, suggesting limited environmental impact of the mine Waste Dump on the surrounding soil ecosystems.
-
natural attenuation of arsenic in soils near a highly contaminated historical mine Waste Dump
Science of The Total Environment, 2012Co-Authors: Petr Drahota, Michal Filippi, Martin Mihaljevic, Vojtěch Ettler, Jan Rohovec, Ondřej SebekAbstract:Abstract Arsenic-contaminated soils near historical As-rich mine Waste in Jachymov (Czech Rep.), resulting from the smelting and seepage of the mine Waste pore water, were studied to examine As partitioning between solid phases and pore waters. Mineralogical and geochemical analyses showed that As is exclusively associated with unidentified amorphous Fe oxyhydroxides, poorly crystalline goethite and hematite as adsorbed and coprecipitated species (with up to 3.2 wt.% As). Adsorption of As by Fe oxyhydroxides is likely to be a major control on the migration of As in the soil pore water containing only up to 15 μg L− 1 As(V). The slight variations in the dissolved As(V) concentrations do not follow the total contents of As in the soil or adsorbed As, but appeared to be a function of pH-dependent sorption onto Fe oxyhydroxides. The geochemical modelling using PHREEQC-2 supported the efficiency of As(V) adsorption by Fe oxyhydroxides in the soil affected by As-rich Waste solution seepage. It also suggested that active Fe oxyhydroxides has a strong attenuation capacity in soil that could effectively trap the aqueous As(V) from the unremitting Waste seepage for the next approx. 11600 years.
Tangfu Xiao - One of the best experts on this subject based on the ideXlab platform.
-
comparative analyses of the microbial communities inhabiting coal mining Waste Dump and an adjacent acid mine drainage creek
Microbial Ecology, 2019Co-Authors: Enzong Xiao, Baoqin Li, Valdis Krumins, Yiran Dong, Jie Deng, Qi Wang, Tangfu XiaoAbstract:Microbial communities inhabiting the acid mine drainage (AMD) have been extensively studied, but the microbial communities in the coal mining Waste Dump that may generate the AMD are still relatively under-explored. In this study, we characterized the microbial communities within these under-explored extreme habitats and compared with those in the downstream AMD creek. In addition, the interplay between the microbiota and the environmental parameters was statistically investigated. A Random Forest ensemble model indicated that pH was the most important environmental parameter influencing microbial community and diversity. Parameters associated with nitrogen cycling were also critical factors, with positive effects on microbial diversity, while S-related parameters had negative effects. The microbial community analysis also indicated that the microbial assemblage was driven by pH. Various taxa were enriched in different pH ranges: Sulfobacillus was the indicator genus in samples with pH < 3 while Acidobacteriaceae-affiliated bacteria prevailed in samples with 3 < pH < 3.5. The detection of some lineages that are seldom reported in mining areas suggested the coal mining Dumps may be a reservoir of phylogenetic novelty. For example, potential nitrogen fixers, autotrophs, and heterotrophs may form diverse communities that actively self-perpetuate pyrite dissolution and acidic Waste generation, suggesting unique ecological strategies adopted by these innate microorganisms. In addition, co-occurrence network analyses suggest that members of Acidimicrobiales play important roles in interactions with other taxa, especially Fe- and S-oxidizing bacteria such as Sulfobacillus spp.
M Osanloo - One of the best experts on this subject based on the ideXlab platform.
-
a new developed model to determine Waste Dump site selection in open pit mines an approach to minimize haul road construction cost
International Journal of Engineering, 2020Co-Authors: A Hajarian, M OsanlooAbstract:Today, during the life of an open pit mine, million tons of materials, including Waste and ore, are displaced by truck fleets. In the case of a shallow ore deposit, which is located up to 300 meters to the ground surface, depending on preliminary equipment size and capacity, it will take three to five years to remove overburden and Waste rocks to expose the ore body. In that period, the main Waste Dump site will be used as a disposal of Waste Dump. Apart from considering the characteristics of the Waste Dump location such as geological and geotechnical properties, the major factors influencing the hauling process are topography, hauling length and construction cost of the haul road. Truck transportation cost depending on the circumstances comprises 45 to 60% of the cost of mining of one tonne ore. Thus, well site selection of Waste Dump in coordination with the main haul road path confidently leads to a significant saving of economic resources. In this research, while identifying the effective factors in selecting the Waste Dump sites, a linear mathematical model is developed to find a suitable site for Waste Dump disposal considering minimizing haul road construction cost.
-
new approach for selection of Waste Dump sites in open pit mines
Mining Technology, 2008Co-Authors: Asieh Hekmat, M Osanloo, Akbarpour M ShiraziAbstract:AbstractOwing to the nature of surface mining, the volumes of mining Wastes are significantly large, which are usually the most visual landforms left after open pit mining. Increased public concerns regarding toxicity and contaminated material of mine Wastes have forced a re-evaluation of the risk and acceptability of mining in most areas. For these reasons, a careful selection of Waste Dump sites, particularly hazardous ones, is very important. Before selecting the most suitable place for large volume of Waste and low grade material, a series of studies must be carried out. In each case, it is important to be able to compare and weigh components to effectively select the most appropriate Dump site. This paper presents an approach to Waste Dump site selection in open pit mines using the integration of multiattribute decision making (MADM) methods. Different MADM methods often produce different outcomes. To make the best decision for Dump site selection, the results of subjective and objective MADM methods...
M O Olorunfemi - One of the best experts on this subject based on the ideXlab platform.
-
integrated geophysical and hydro chemical investigations of impact of the ijemikin Waste Dump site in akure southwestern nigeria on groundwater quality
Social Science Research Network, 2019Co-Authors: Oluwaseun E Odipe, Rasheed Ogunleye, Musa Sulaiman, Suleiman S Abubakar, M O OlorunfemiAbstract:Background: Improper Waste disposal can negatively impact the ecosystem and constitutes a major human health risk. Objectives: The present study evaluated the environmental impact on groundwater quality of an open-air Waste Dump in Akure, southwestern Nigeria, using an integrated geophysical survey and hydro-chemical analysis of water samples. Methods: The geophysical survey involved three dipole-dipole 2-D imaging profiles and seven vertical electrical soundings (VES) along three traverses. The dipole-dipole data were inverted using the Dipro for Windows software, while the VES data were quantitatively interpreted using partial curve matching and computer assisted 1-D forward modeling with the WINResist software. The VES interpretation results were used to generate geoelectric sections. For the hydro-chemical analysis, samples were taken from five hand-dug wells at various distances from the Dumpsite. The samples were analyzed for temperature, pH, conductivity, total dissolved solids (TDS), and some major elements (calcium ion (Ca2+), magnesium ion (Mg2+), chloride ion (Cl-), nitrate (NO3-), sulfate (SO42-)) whose concentration values were compared with World Health Organization (WHO) and Nigerian Industrial Standard (NIS) standards for assessment of groundwater quality. Results: The VES curves revealed three distinct geoelectric/geologic layers with thicknesses and resistivities in the range of 0.7 - 2.0 m and 31 - 55 Ωm for topsoil, 6.2 - 14.6 m and 13 - 114 Ωm for the weathered layer, and a fresh basement with resistivity values ranging from 344 -∞ Ωm. In the hydro-chemical analysis, pH values ranged between 7.57 - 7.8, electrical conductivity ranged from 884 - 1510 μS/cm, and TDS ranged between 588 - 1008 mg/l. Concentration values of Ca2+ and Mg2+ ranged between 78 - 132 mg/l and 1.8 - 19 mg/l, respectively. Conclusions: The results from the combined electrical resistivity methods showed relatively low resistivity values at the topsoil and weathered layers and the hydro-chemical assessment of water samples indicated that the topsoil and groundwater within the Dumpsite may have been polluted by leachate.
-
geophysical and hydro chemical investigation of the area around a Waste Dump site in ile ife southwest nigeria
Global Journal of Geological Sciences, 2009Co-Authors: K O Obase, M O Olorunfemi, J O AkintorinwaAbstract:An integrated geophysical and hydro-chemical investigation was carried out in the area around the Stadium-Apollo Market Waste Dump located in Igboya area of Ile-Ife. It was with the aim of determining the geoelectric characteristics and groundwater chemistry which were used in delineating the subsurface sequence and evaluating the possible pollution of groundwater in the area. Eight Vertical Electrical Sounding (VES) stations were occupied along two traverse lines trending North-South and East-West directions. Dipole-Dipole profilings were also carried out along same traverses. Eight water samples were collected from hand dug wells and analyzed for some chemical elements such as total acidity, major ions (Na+, K+, Cl-, Mg2+, Ca2+), NO3- and heavy metals (Cd, Cu, Fe, Hg, and Pb). Results of the investigation indicate that a maximum of four subsurface layers- the top soil, clay/sandy clay unit, the weathered layer and the basement bedrock exist in the area. The weathered layer constitutes the main aquifer unit with thicknesses of between 7 and 38 m. From the 2-D resistivity structures, contaminant plumes characterized by relatively low resistivity values ( KEYWORDS: Geophysical, Hydro-chemical, Waste Dump, Groundwater Quality, Pollution
