| 1. |
- Nilsson, Charlotte, 1985-, et al.
(författare)
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Municipal sludge ash for abatement of ARD
- 2016
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Ingår i: Mining Meets Water – Conflicts and Solutions. - Freiberg : TU Bergakademie Freiberg, Institute of Mining and Special Civil Engineering. - 9783860125335 ; , s. 699-705
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Konferensbidrag (refereegranskat)abstract
- Abatement of ARD with passive treatment systems can quite often rely only on pH-control if the iron content is high enough and to allow for the formation of ferric hydrous oxides, which act as efficient adsorbents. The stability of ferric hydrous oxides is sensitive to lowering of pH as well as Eh why they must be controlled. Hence, it would be favourable to use a well ordered adsorbent that is stable over time and under the chemical conditions of ARD. Municipal waste water sludge is a growing problem in many countries and incineration under oxidative conditions can be used to oxidize anthropogenic organic molecules which pose a threat to the environment. Sludge ashes rendering from wastewater treatment in which iron is used as a flocculation agent have high concentrations of calcium/ magnesium and ferric oxides, and should therefore, in theory be a suitable candidate for treatment of ARD. This study has therefore focused on the ability for these ashes to act as a sorbent for the removal of metals from ARD. The stability and potential release of metals from the material were quantified in batch experiments by extraction at pH 2-10, resulting in equilibrium concentrations (at pH 8) of 11.9, 0.08 and 24.1 mg L-1 for Al, Fe and Mn respectively. However, after washing with water the corresponding values were 0.01, 0.03 and 0.09 mgL(-1). In fact, after washing the sludge ash is stable from pH 4 to 10, with only slightly higher concentrations found at pH 2. Batch experiments on metal adsorption from ARD showed more than 99% sorption of Cr, Cu, Pb and V, corresponding values for Co, Ni and Zn were 56, 86 and 34% respectively. The overall results from this study show that sludge ashes are a promising solution for treatment of ARD.
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| 2. |
- Qureshi, Asif, et al.
(författare)
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Characterisation of fly ashes for minimisation of acid mine drainage from coal mining waste rocks
- 2016
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Ingår i: Mining meets water. - Freiberg : TU Bergakademie Freiberg, Institute of Mining and Special Civil Engineering. - 9783860125335 ; , s. 977-986
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Konferensbidrag (refereegranskat)abstract
- Acid mine drainage (AMD) due to the oxidation of sulphide bearing waste rock (WR) is a common environmental problem associated with coal extraction. Therefore, WRs from a lignite producing coal field in Pakistan and Lignite (PK), bituminous (FI) and biomass (SE) fly ashes (FAs) were mineralogically and chemically characterised to i) estimate the potential of WRs for generating AMD ii) estimate their deteriorating effects on natural waters, and iii) evaluate the FAs for their potential to minimise the impacts of WRs by preventing and/or neutralising AMD. The WRs were composed of quartz, pyrite, arsenopyrite, kaolinite, hematite and gypsum with traces of calcite, malladerite, spangolite, franklinite and birnessite. The major elements Si, Al, Ca and Fe were in the range (wt. %) of 8 – 12, 6 – 9, 0.3 – 3 and 1 – 10, respectively, with high S concentrations (1.94 – 11.33 wt. %). All FAs contained quartz, with iron oxide, anhydrite and magnesioferrite in PK, mullite and lime in FI and calcite and anorthite in SE. The Ca content in SE was 6 and 8 times higher compared to PK and FI, respectively.The WRs had considerable potential for generating AMD with net neutralisation potential corresponding to-70 to-492 kg CaCO3 tonne-1. FAs showed to have sufficient acid neutralisation potential corresponding to 20 – 275 kg CaCO3 tonne-1 , SE being the most alkaline probably due to the higher Ca content. The element leaching varied between the WRs due to their chemical and mineralogical composition and pH conditions during the weathering cell test for 28 weeks. However, in general, the leachates from the more acidic WRs were enriched about 3 to 4 orders of magnitude for certain elements compared to the less acidic WRs. The concentrations of Ca, SO42-, Na and Cl in the leachates were much higher compared to other elements from all FA samples. Iron, Cu and Hg were not detected in any of the FA leachates because of pH ranging from 9 to 13.Overall, the WRs had considerable potential for AMD generation and element leaching, therefore, deteriorate natural waters within the mining area. FAs, on the other hand, possess potential to minimise the impacts of WRs on the environment, due to their buffering capacity. However, the FAs vary in chemical composition and buffering capacity depending on their source, which makes it a possible challenge for utilisation.
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| 3. |
- Sartz, Lotta, 1979-, et al.
(författare)
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Development of a low-tech treatment for neutral mine water : a case study
- 2016
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Ingår i: Mining Meets Water. - Freiberg, Germany : TU Bergakademie Freiberg, Institute of Mining and Special Civil Engineering. - 9783860125335 ; , s. 913-918
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Konferensbidrag (refereegranskat)abstract
- Lovisagruvan is a Pb-Zn-Ag mine in mid-south Sweden, with a yearly production of some 40 000 tons. There are four main levels in the mine: 55, 105, 145 and 190 m below ground. Water is continously pumped at a rate of 5 m3/h, passing sedimentation pools at each of the four main levels in the mine and finally one above ground. A modified backfill mining is used and in order to visually separate the ore from the waste rock limestone is used as a separating layer. Limestone addition in combination with non-acid producing mineralisation generates a pH-neutral mine water. For many years the mine has had problems with high levels of zinc and lead in the mine water released to recipient. The primary contaminants, lead and zinc, were mainly found as particles or associated to particles. With a combination of several measures including a sandfilter and FeSO4 addition suspended matter was reduced 93 %, lead 91 % and zinc 71 %.
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| 4. |
- Siren, Susanne, et al.
(författare)
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Green liquor dregs in mine waste remediation, from laboratory investigations to field application
- 2016
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Ingår i: Mining Meets Wate. - Freiberg : TU Bergakademie Freiberg, Institute of Mining and Special Civil Engineering. - 9783860125335 ; , s. 706-713
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Konferensbidrag (refereegranskat)abstract
- The oxidation of sulphides in mine wastes is a possible threat to the environment as it has potential to generate acid rock drainage (ARD). A way to reduce ARD formation is to apply a soil cover to reduce oxygen fluxes and water infiltration to the underlying reactive wastes. A typical mine waste cover in Sweden consists of a compacted sealing layer of a fine grained till overlaid by an on-compacted protection layer. However, a fine grained till with low enough hydraulic conductivity (HC) can be difficult to find in the vicinity of the mine and it might be necessary to mix it with a fine grained material. In this study a mixture of till and a residue from pulp and paper production, Green Liquor Dregs (GLD) was studied in laboratory and in a pilot cell study. The objective of the laboratory study was to investigate if an addition of GLD will improve the HC of tills with different clay contents. The results show that HC of the different tills studied decreases with addition of 5-10 w.% of GLD, except from the clayey till that already had a low HC without addition of GLD. In the pilot scale study a cell was constructed to investigate the feasibility to compact a sealing layer of a fine grained till and 10 w. % of GLD. The pilot scale study shows that it can be difficult to reach a high compaction degree in the field. However, it does not necessarily mean that the HC of the sealing layer will increase. In fact the laboratory study shows the opposite trend, a decrease in HC with a decrease in dry density for tills with low clay content. The main conclusion of the study is that addition of GLD can be an alternative option to improve the properties of a local till that alone does not meet the requirements for HC.
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| 5. |
- Sjöberg, Susanne, et al.
(författare)
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REE-Enriched Mn-Oxide Precipitates in Water-Bearing Fractures in the Ytterby Mine, Sweden
- 2016
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Ingår i: Mining Meets Water – Conflicts and Solutions. - Freiberg : TU Bergakademie Freiberg, Institute of Mining and Special Civil Engineering. - 9783860125335 ; , s. 346-352
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Konferensbidrag (refereegranskat)abstract
- The Ytterby mine, Sweden, is known for the discovery of eight elements, including yttrium and five of the rare earth elements (REE). The mine was in operation from 1750 to 1933 and was after closure used as a storage depot for fuel from the 1950s to 1995. A tunnel was opened in the 1950s through the bedrock into the mine to allow access to the storage depot. Recent water monitoring campaigns (20122015) in the mine revealed a black substance (denoted YBS) in some fractures opening into the tunnel. Analysis of the YBS (elemental analysis, phase analysis by XRD, SEM with energy dispersive X-ray spectrometry, IR-and EPR-spectroscopy, preferential leaching at pH 4) showed that the main mineral component of the YBS is the manganese oxide birnessite. Also minor quantities of other less well defined manganese oxides were found, as well as silicates (quartz grains, possibly feldspar grains) and calcite. Birnessite has typically the composition Mx(Mn3+, Mn(2)(4+))O(4)xAq, with M= Na, Ca and x= 0.5. The birnessite component in YBS had a Mn3+/Mn4+ ratio of 1.04/0.96 with M = 0.42 Ca + 0.03 (REE+Y), 0.03 Mg and 0.03 other metals. All of these metals were firmly associated with the structure, since no release was observed at pH 4, except for significant fractions of the total Na, Mg, Ca-contents. Thus, REE+Y correspond to 1% of the total YBS mass and up to 3% of the metal content in the birnessite phase. This corresponds to an REE enrichment factor of the order 106 (YBS-birnessite/ fracture water). Birnessite with a substantial fraction of REE in the lattice has not previously been reported. The formation of birnessite is a microbial process. Identification of the microorganisms present in the Ytterby system is in progress.
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| 6. |
- Åhlgren, Kristina, 1976-, et al.
(författare)
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Identification of major point sources in the severely contaminated alum shale area in Kvarntorp, Sweden
- 2016
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Ingår i: Mining Meets Water – Conflicts and Solutions. - Freiberg : TU Bergakademie Freiberg, Institute of Mining and Special Civil Engineering. - 9783860125335 ; , s. 377-382
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Konferensbidrag (refereegranskat)abstract
- Scarcity of imported fuel led to oil production from alum shale in the Kvarntorp area, 200 km west of Stockholm, during 1941-1966. Remains from this are a 100 meter high waste deposit, Kvarntorpshogen, consisting mostly of shale ash and water filled open pits. As this shale is rich in sulphur and trace metals such as U, Ni and Mo, leaching from the waste deposit is feared. To elucidate the important question whether Kvarntorpshgen is the most important concern, or to what extent other sources might contribute with contamination, water sampling was extended to contain more localities than the ordinary control program. A new approach was the sulphur isotope analysis. The results point towards an area too complex for using sulphur isotopes for mixing calculations. Isotope fractionation during oil production is shown by the delta(34) difference between shale and shale ash. Current isotope fractionation indicates sulphate reduction. Some localities indicate pyrite weathering and others rather show buffer capacities due to the presence of lime. Sr concentrations also suggest weathering. It is indicated that Kvarntorpshgen has an impact on the surroundings, but also that the water filled open pits as well as an industrial area affect the water quality. It is concluded that Kvarntorpshgen is one of the most important contributors of metal dispersion, but other point sources cannot be discarded as environmental risks.
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