Im Artikel werden deterministische und probabilistische Verfahren zur Bewertung des Risikos in tagesbruchgefährdeten Braunkohlengebieten vorgestellt und verglichen. Dabei wird besonders auf die Theorien zu den Bruchwahrscheinlichkeiten nach Fenk und Päßler eingegangen und die wechselseitigen Abhängigkeiten beleuchtet. Weiterhin werden die Möglichkeiten eines altbergbaulichen Risikomanagementes auf der Basis von Bruchwahrscheinlichkeiten mit ihren Vor- und Nachteilen aufgezeigt.

Syftet med denna uppsats var att söka förståelse till varför den nedlagda gruvan i Nautanen fortsätter att förorena miljön i närområdet. Utifrån aktör- och nätverksteori har utgångspunkten varit den att olika aktörer har haft olika intressen i Nautanen. Alla aktörer har studerats neutralt och utgångspunkten har varit den att det existerar en ontologisk jämlikhet mellan aktörerna – ingen är starkare än den andra. Genom en kvalitativ fallstudiemetod har olika material bearbetats. Undersökningen visade att försöken på efterbehandling inte genomfördes till dess fullo. Detta beror på att två aktörer, Gällivare kommun och markägaren Sveaskog, inte kunde komma överens om framtidsansvaret för Nautanen. Således resulterade det i att projektet avslutades och föroreningarna fortsatte att förorena. Genom att analysera resultatet lyfts olika belägg för olika slutsatser om vilken aktör som är den starkare aktören samt ansvarig till varför Nautanen fortsätter att förorena. Är det Gällivare kommun eller Sveaskog? Är det lagstiftningen eller staten? / The purpose of this essay was to understand why the old mining site in Nautanen continues to pollute the enviroment in the immediate area. Based on the actor-network theory, different actors have had different interests in Nautanen. All actors have been studied neutrally and the starting point has been that there is an ontological equality between the actors – no actor is stronger than the other. Different materials have been processed through a qualitative case study method. The study showed that the post-treatment trials were not fully carried out. This was because two actors, Gällivare municipality and the landowner Sveaskog, were unable to agree on the future responsibility for Nautanen. Thus, it resulted in the project coming to an end and the pollution continuing to pollute. Analyzing the results highlights different evidence for different conclusions about wich actor is the stronger actor and is responsible for why Nautanen continues to pollute. Is it Gällivare municipality or Sveaskog? Is it the law or the state?

>Magister Scientiae - MSc / Mining has a lengthy history in South Africa, and subsequent beneficiation processes have been conducted with little regard for the environment, thus leaving the land with un-rehabilitated abandoned mines. Currently, most of these abandoned mine sites are no longer operational and they continuously contaminate soil, air and water resources in various areas where mining took place. This study looks at the treatment of contaminated mine water using the Dispersed Alkaline Substrates (DAS) which is a new South African technology that uses a variety of substrates to neutralize and raise the pH of mine water while lowering the solubility of potentially dangerous metals.

Mining processes generate waste rock, tailings, and slag that can increase heavy metal concentrations in soils. Un-reclaimed, abandoned mine sites are particularly prone to leaching these contaminants, which may accumulate and pose significant environmental and public health concerns. The characterization and spatial delineation of heavy metals of such soils is vital for risk assessment and soil reclamation. Bumpus Cove, once one of the richest mineralized districts of eastern TN, is home to at least 47 abandoned, un-reclaimed mines that were all permanently closed by the 1950s. This study evaluated 52 soil samples collected within a 0.67 km2 study area containing 6 known abandoned Pb, Zn, and Mn mines at the headwaters of Bumpus Cove Creek for heavy metal concentrations. Soil samples were analyzed for Zn, Mn, Pb, Cu, and Cd by means of microwave-assisted acid digestion and flame atomic absorption spectrometry (FAAS). Using the measured values and digital elevation model (DEM) derived from lidar data, ordinary kriging and cokriging interpolation techniques were used to predict the trend of heavy metal concentrations throughout the study area. Concentrations for Zn, Mn, and Pb show significant variability between sample sites (ranges of 12 – 1,354 mg/kg Zn, 6 – 2,574 mg/kg Mn, 33 – 2,271 mg/kg Pb). Cu and Cd were much less variable, with ranges of 1 - 65 mg/kg and 7 – 40 mg/kg, respectively. Of the measured heavy metals, only Zn and Pb exceed permissible limits in soils. Results show that ordinary kriging interpolation methods produced improved results over ordinary cokriging with and without lognormal transformations for all metals. Mn and Pb were found to transport further downhill following the natural drainage, whereas Zn, Cu and Cd concentrations exhibit localized variability without a clear transportation path. This study can provide a reference for state and local entities responsible for heavy metal monitoring in Bumpus Cove, TN.

Department of Mining and Environmental Geology / MESC

Thesis (M.Sc. (Geology)) -- University of Limpopo, 2022 / The Two Rivers Platinum Mine (TRP) located in the Eastern Bushveld Igneous Complex is currently exploiting platinum-group elements (PGE) in the Upper Group 2 chromitite (UG2) Reef at the Dwarsrivier Farm. TRP has acquired a new prospect (at the Buffelshoek Farm) and is currently planning to mine the UG2 Reef and potentially also the Merensky Reef (MR). Three drill-cores which intersected the UG2 Reef and MR at the Buffelshoek Farm made available by TRP were sampled for mineralogical studies using complementary techniques including reflected light microscopy, mineral liberation analyser and electron microprobe. The platinum group minerals (PGM) which host the PGE exhibit variability in their flotation rates and consequently variable PGE recoveries that is mostly attributed to the not so well understood PGM distributions and characteristics. The purpose of the study was to investigate the PGE process mineralogical characteristics such as the PGM phases, their modal abundances and mineral associations, as well as the grain size distributions within the UG2 Reef and MR at the Buffelshoek Farm. The observed PGM phases are broadly grouped into PGE sulphides, PGE arsenides, PGE bismuth-tellurides, PGE antimonides and PGE alloys. The PGM phases are largely dominated by PGE-sulphides (average of 80%) in the UG2 Reef and PGE-arsenides (average of 39%) in the MR. Although the UG2 Reef and MR are mineralogically different, the PGM observed are similar in composition, but vary in their proportions. The PGM are mostly associated with base metal sulphides typically, pentlandite in the UG2 Reef and silicates, which are dominated by amphiboles in the MR. The PGM grain sizes generally range between 2 and 22 microns in the UG2 Reef and range between 2 and 32 microns in the MR. The concentrations of platinum are the highest in both the UG2 Reef and MR, and with the platinum largely deported in PGE-sulphides (about 69 - 84.9%) in the UG2 Reef and PGE-arsenides in the MR. Palladium is mostly deported in the PGE sulphides (about 52.3 - 69.2%) in the UG2 Reef and mostly deported in PGE antimonides (about 43%) and PGE bismuth-tellurides (about 37%) in the MR. Rhodium (Rh) is entirely deported in the PGE sulphides in the UG2 Reef and deported in PGE sulphides (about 86.5%) and PGE bismuth-tellurides (about 13.5%) in the MR. Expected recoveries of PGM ranges from 76 to 89% for PGE sulphides and arsenides in the UG2 Reef and 61.3% in the MR, which is considered good. PGE bismuth-tellurides, PGE antimonides and PGE alloys are expected to be variably to poorly recovered, requiring suitable reagents to be well recovered both in the UG2 Reef and MR. / Faculty of Science and Agriculture Research Division Geological Society of South Africa North West University's School of Geo- and Spatial Science

No description available.

[Truncated abstract] Acidic mine lakes are formed as a result of the oxidation and dissolution of metal sulfide minerals and are primarily characterized by low pH values of 2 – 4. Many strategies for the bioremediation of acidic mine lakes depend on the alkalinity generation capabilities of microbial ferric and/or sulfate reducing bacteria. However nearly all mine lakes are oligotrophic, with very low concentrations of available organic carbon and nutrients; all required for healthy microbial growth. There is also an unusual class of mine lakes characterized by low concentrations of organic carbon and also very low concentrations of dissolved iron and sulfate. Our ability to promote microbial activity in these systems is especially challenging. This study focuses on one of these systems, Lake Kepwari, a coal mine lake in Western Australia. Numerical modeling of remediation strategies is an efficient way of testing scenarios prior to expensive in-field trials. However such modeling relies on good descriptions of microbial processes, including kinetic parameterizations of ferric and sulfate reduction. There has been little research to date on the study of kinetic parameterizations of the chemical and biological alkalinity generation in acidic mine lakes. The objectives of this thesis were to investigate the viability of microbial ferric and sulfate reduction in an ultraoligotrophic, acidic mine lake, to assess the impact of these microbial processes on water quality and to parameterize the Dual Monod kinetics of neutralization under dual limitation conditions. Molecular analyses including most probable number, DNA extraction, polymerase chain reaction, polymerase chain reaction – denaturing gradient gel electrophoresis were used to examine the microbial communities in the lake sediments. ... The Monod maximum specific microbial growth rates with respect to dissolved organic carbon and ferric, and as determined in batch experiments, were 0.07 ± 0.01 and 0.048 ± 0.02 day-1, respectively, and their corresponding Monod half saturation constants and were 14.37 and 5.6 mmol L-1. The Monod maximum consumption rates under ferric and OC limitation were also estimated. The Monod maximum specific microbial growth rates with respect to dissolved organic carbon and sulfate, , and were 0.05 ± 0.01, 0.08 ± 0.01 and 0.07 ± 0.02 day-1, respectively, and their corresponding Monod half saturation constants, and were 75.5, 131.8 and 10.2 mmol L-1. The Monod maximum consumption rates under sulfate and OC limitation were also estimated. The results of this study suggest that strategies for the remediation of ultraoligotrophic, acidic mine lakes may rely on microbial ferric and sulfate reduction, however additions of both organic carbon and sulfate/ferric are essential. These results can be immediately applied to mesocosm studies in outdoor enclosures and to the management of acidic mine lakes. Furthermore, this thesis has provided a new, valuable understanding on the Dual Monod kinetic parameterizations of neutralization for an ultraoligotrophic, acidic mine lake environment. These parameterizations are essential for the lake ecological models that will be used to investigate remediation scenarios for acidic mine lakes.

MENVSC / Department of Ecology and Resource Management / Historically, mining activities have generated vast quantities of abandoned tailings dumps in several regions of South Africa and throughout the world. The management and disposal of huge volumes of tailings dumps has constituted a major challenge to the environment. The current study aims to establish the physicochemical properties and mineralogical characterization of the old copper tailings dump in Musina, to reveal the mobility patterns and attenuation dynamics of potentially toxic or heavy metal species as a function of depth, with a view of assessing their potential environmental impact with respect to surface and ground water systems. This information is crucial in the beneficial utilization of copper tailings in the development of sustainable construction materials as part of reuse approach management system. About twelve tailings samples were collected into polyethylene plastic bags from three established tailings profiles drilled by a hand auger. The collected tailings samples were characterized using standard analytical procedures i.e., X-ray fluorescence (XRF), X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive spectroscopy (SEM-EDS). The transfer of potentially toxic or heavy metal species from tailings to water was evaluated using the standardized batch leaching test (EN 12457) and speciation-equilibrium calculations on the aqueous extracts performed by MINTEQA2. The leachate concentration of cations in the collected tailings samples was determined by inductively coupled mass spectrometry (ICP-MS) and the leachate concentration of anions was determined by ion chromatography (IC). A modified sequential extraction scheme was applied on the selected tailings samples of the drilled tailings profiles to further understand the mode of occurrence, the geochemical partitioning and distribution, real mobility, and environmental bioavailability of potentially toxic or heavy metal species in the tailings and tailings-soil interface. The extracted fractions or phases from sequential scheme were as follows: (F1) water-soluble fraction, (F2) exchangeable fraction, (F3) carbonate fraction, (F4) iron and manganese hydroxide associated fraction, (F5) organic matter and secondary sulphide associated fraction, (F6) primary sulphide bound fraction, and (F7) residual or silicate fraction. The results obtained from the seven steps sequential extraction scheme were validated by the determination vi of percentage recoveries from pseudo-total digestion or total metal content of the original sample. The distribution of major elements and potentially toxic or heavy metal species in different leachate fractions obtained after each step of sequential extraction of the selected tailings samples was determined by inductively coupled plasma mass spectrometry (ICP-MS). The appraised data was used to reveal the impact of atmospheric oxygen and infiltrating rain-water on the chemistry of copper tailings dump by depth profiles. Macroscopic properties revealed that the abandoned Musina copper tailings are fine to medium coarse grained, and range in color from light/dark gray at the upper or shallow depth of the tailings, to dark reddish-brown at the deeper zone where the tailings are mixed with the underlying soil or soil-interface. The drilled respective tailings profiles were uniform and slightly varied in both mineralogical and bulk chemical compositions with tailings depth. Mineralogical analysis showed the following order of mineralogical composition within the respective tailings profiles: quartz> epidote> chlorite> muscovite> calcite> hematite. Chalcopyrite was the only sulphide mineral observed by optical microscopy, although not identified or quantified by XRD and SEM-EDS analysis. The observed discrete chalcopyrite grains were attributed to the primary mined ore (i.e., chalcopyrite, chalcocite and bornite) during past copper mining activities in Musina. The tailings profiles were characterized by a medium alkaline pH (7.97-8.37) that corresponds very well with the tailings leachates or pore-water pH (8.36-8.46). This pH was constant and slightly varied with tailings depth in the respective tailings profiles. The high abundance of alumino-silicate minerals and traces of carbonates as calcite coupled with low sulphide mineral content, suggested a high neutralization capacity of the tailings which was in common agreement with an alkaline nature of the copper tailings dump. The chemical composition of major elements within the respective tailings profiles followed the order: Si>Al>Fe>Ca>Mg>K>Na, and corresponds very well with the mineralogical composition of the tailings, whereby alumino-silicates were the most abundant minerals in the tailings samples. Nevertheless, the solid-phase concentration of metals decreases with increasing tailings depth as Cu>Sr>Zr>Ni>Zn and was incongruent with the mineralogical composition within the respective tailings profiles. The main secondary minerals were calcite and hematite, and their proportion increased with increasing tailings vii depth. In addition, hematite formed coatings on the rims and corners of chlorite as observed from optical microscopy, and retained relatively high amounts of potentially toxic or heavy metals (up to 862 ppm of Cu, up to 36 ppm of Ni, and up to 25 ppm of Zn) at the upper and shallow depth of the respective tailings profiles, where bulk density was high and low porosity. Based on batch leaching tests, the amounts of potentially toxic or heavy metal species released into solution were low (0.27-0.34 μg/L Pb, 0.54-0.72 μg/L Ni, 0.88-1.80 μg/L Zn, and 20.21-47.9 μg/L Cu) and decreases with increasing tailings depth, indicating that, presently, the tailings have a minor impact on heavy metals load transported to the receiving surface and groundwater systems. The low concentration of potentially toxic or heavy metal species in solution is primarily due to their retention by secondary Fe oxide phases (i.e., hematite) and the prevailing medium alkaline pH condition of the tailings leachate or pore-water. The observations are consistent with MINTEQA2 speciation calculations, which predicted the precipitation of secondary phase cuprite (Cu2O) as the main solubility-controlling mineral phase for Cu, Zn, and Ni. Primary factors influencing aqueous chemistry at the site are neutralization and dissolution reactions as a function of pH, precipitation, and sorption into hydrous oxides (hematite and cuprite). Based on sequential extraction results, the leachable concentration of potentially toxic or heavy metal species in the water-soluble, exchangeable and carbonate fractions of the respective tailings profiles was relatively low, except for Cu and Mn. For instance, the leachable concentration of Cu and Mn reached 10.84 mg/kg and 321.7 mg/kg at the tailings-soil interface (3 m) in tailings profile C, respectively. The low concentration of potentially toxic or heavy metal species (Cr, Co, Ni, Zn, Cd, and Pb) in these fractions could be due to the low solubility of minerals bearing these trace elements caused by variations in pore-water pH in the respective tailings profiles. The high concentration of Cu and Mn in these fractions suggests their high mobility and therefore most available for uptake in the environment. Except for Cu>Mn>Cr, the contents of potentially toxic or heavy metal species in the Fe and Mn oxides and organic matter or sulphides bound fractions was low, due to the low viii quantity of these fractions in the tailings, despite their high affinity and sorption capacity for potentially toxic or heavy metal species. Likewise, the residual fraction of the respective tailings profiles contained the highest proportion of potentially toxic or heavy metal species. Although the highest potentially toxic or heavy metal species content was in fractions with limited mobility, care must be taken since any geochemical change or shift in the tailings pH or acidic conditions may cause them to be displaced to more mobile fractions, thereby increasing their mobility and environmental bioavailability. Therefore, physicochemical properties of the tailings including pH and mineralogical composition of the tailings samples were the main substrate controlling the geochemical partitioning and distribution, potential mobility, and environmental bioavailability of potentially toxic or heavy metal species by tailings depth. The knowledge of mobility and eco-toxicological significance of tailings is needed when considering tailings dump disposal or reuse in the environment. The addition of copper tailings at 3 and 28 days successfully improved the compressive strength of cement mortar mixtures incorporating tailings at C5 (5%) and C10 (10%) respectively, although with small margin relative to the control mixture (C0). The maximum strength was 31.15 Mpa attained after 28 curing days, and slightly varied when compared with other compressive strength on copper blended cement mortars mixtures in other countries, used for the development of sustainable construction materials. The chemical composition, physical properties and improved compressive strength on cement mortars mixtures incorporating copper tailings, implies that copper tailings are suitable for the development of sustainable construction materials, thereby ensuring job creation, availability of land for development usage, and the reduction of environmental pollution induced by the abandoned copper tailings dumps.