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  • 51.
    Karlsson, Stefan
    et al.
    Örebro University, Department of Natural Sciences.
    Bäckström, Mattias
    Örebro University, Department of Natural Sciences.
    Surface water quality in Bersbo, Sweden: fifteen years after amelioration of sulphidic waste2003Conference paper (Refereed)
  • 52.
    Karlsson, Stefan
    et al.
    Örebro University, Department of Natural Sciences.
    Grahn, Evastina
    Örebro University, Department of Natural Sciences.
    Düker, Anders
    Örebro University, Department of Natural Sciences.
    Bäckström, Mattias
    Örebro University, Department of Natural Sciences.
    Historical pollution of seldom monitored trace elements in Sweden - Part A: sediment properties and chronological indicators2006In: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 8, no 7, p. 721-731Article in journal (Refereed)
    Abstract [en]

    Sediment cores from four small oligotrophic boreal lakes, with minor acidification, in remote regions of central Sweden were used for historical interpretation of their metal content, with focus on Cu, Cd, Pb and Zn in Lake Stensjön, which has the longest sediment record (at least two centuries according to 210Pb dating). Comparison is made with the other three lakes. Major and trace elements in lake water, porewater and the acid-leached (HNO3) solid sediment phase was analysed with ICP-MS. In addition, general lake water chemistry, TOC and principal anions were measured in the aqueous phases. Redistribution processes were interpreted from geochemical modelling. The solid/solution distribution of pe/pH sensitive elements, indicates a minor diagenetic redistribution and the concentration profiles are therefore suitable for chronological evaluation. The ratios of Al, Ti, Sc and V, indicated a qualitative shift of sedimenting material a century ago, which did not have any impact on the retention of trace elements. Lead had a concentration profile, supported by the 206Pb/207Pb ratio, where it was possible to distinguish preindustrial conditions, early industrialisation in Europe, industrialisation in Sweden, and the use of leaded petrol after the Second World War. Cadmium showed a similar concentration pattern. The zinc profile resembled that of cadmium, but with less enrichment. Local lithogenic sources are believed to be quantitatively important. The solid/solution distribution (Kd) was independent of depth for all four elements. The sediment concentrations of copper and zinc are not related to early industrialisation but its concentration has doubled since the Second World War.

  • 53.
    Karlsson, Stefan
    et al.
    Örebro University, School of Science and Technology.
    Karlsson, Lovisa
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Sjöberg, Viktor
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Water quality in a black shale mining area: effects of pH and natural organic acids on weathering and subsequent metal releases2014In: An Interdisciplinary Response to Mine Water Challenges / [ed] Wanghua Sui, Yajun Sun and Changshen Wang, China University of Mining and Techno logy Press , 2014, p. 136-136Conference paper (Refereed)
    Abstract [en]

    Mining of black shale (alum shale) of Late Cambrium age for the extraction of alum started in the early 17th century in Sweden, and in the late 19th century there was an extensive use of shale, with its high content of organic carbon, as fuel in lime-burning processes. Full-scale recovery of hydrocarbons from shale took place in Kvarntorp during 1942-66, and recovery of uranium in Ranstad during 1965-76. Remains from the historic mining and processing of black shale are some 50 major deposits with processed and unprocessed shale residues, as well as water-filled pits, at the former mining sites. There are also large areas covered with crushed shale, e.g. as road filling material. Studies of the weathering of shale due to exposure to the atmosphere and water with pH within the natural range indicate a high leachability of cationic elements at low pH, as well as anionic elements at high pH. The presence of organic complexing acids of natural origin (microbial exudates and humic acids) may give an enhanced leaching, particularly at pH above 8, when hydroxy-groups would constitute active metal binding sites. Results from studies of weathering and leaching of processed and unprocessed black shale are presented, as well as the effects on the water quality observed at former mining sites and related environmental impact.

  • 54.
    Karlsson, Stefan
    et al.
    Örebro University, School of Science and Technology.
    Sartz, Lotta
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Abatement of ARD with solid alkaline waste materials: A meso-scale field test with emphasis on general hydrochemical parameters2009In: Securing the Future and 8th ICARD, 2009, p. 10 pages-Conference paper (Refereed)
    Abstract [en]

    Abatement of acid mine drainage (ARD) can be made by controlling pH and Eh of the effluents, to optimise retention of major and trace components. The use of solid alkaline waste products from lime production, pulp and paper industry and steel production as well as ashes from bio fuels was evaluated in a meso-scaleexperiment. Each test system hadthree 0.4 m3barrelsthat contained the alkaline waste, a passive support and peat nuggets, in this order.The alkaline wastes consisted of lime kiln dust (LKD), green liquor dreg (GLD), lime mud (LM), LD-slag and fresh and aged ashes. The ARD came either from reactors with acid waste or water taken from a nearby mine shaft. Neutralization was observed for fresh ash, LKD, LD and LM/ash with pH of 6.5, 8.9, 5.3 and 6.6, respectively. The corresponding alkalinities were 0.3, 10.1, 1.8 and 0.5 meqv/l. For carbonated ash and GLD the pH was 3.9 and 4.7 and with acidity remaining. In the best performing systems the average trace metal retention was Pb (>99%), Cu (>99%), Cd (90%) and Zn (70%).

  • 55.
    Karlsson, Stefan
    et al.
    Örebro University, School of Science and Technology.
    Sjöberg, Viktor
    Örebro University, School of Science and Technology.
    Ogar, Anna
    Dep. Environ. Sci., Jagellonian University, Krakow, Poland.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Leachability of Cu, Zn, As, Ba and Pb from refuse in the Zelazny Most tailings dam2014In: Annual International Mine Water Association Conference: An Interdisciplinary Response to Mine Water Challenges / [ed] Sui, W., Sun, Y. & Wang, C., Xuzhou, China: China University of Mining and Technology Press , 2014, p. 121-125Conference paper (Refereed)
    Abstract [en]

    In order to establish plants on any kind of mine waste it is essential to determine its chemical properties, i.e. the potential to release elements. In this study we combine chemical extraction of six different solid metal species (water soluble, ion-exchangeable, carbonate, reducible, oxidizable acid leachable) on tailings from Zelazny Most, Poland. The results show that the plants encounter an environment with circumneutral pH and high availability of Ca, Na, and Cu. During reducing conditions there is also an increasing availability of As, Fe, Pb, and Zn.

  • 56.
    Karlsson, Ulrika
    et al.
    Örebro University, Department of Natural Sciences.
    Karlsson, Stefan
    Örebro University, Department of Natural Sciences.
    Düker, Anders
    Bäckström, Mattias
    Assessing the release of thallium, cadmium, lead, copper and zinc from deposits with mixed wastes: a case studyManuscript (Other academic)
  • 57. Lind, Bo
    et al.
    Bäckström, Mattias
    Örebro University, Department of Natural Sciences.
    Geisler, Erika
    First flush effect of metals and anions in stormwater runoff from roads in mid-Sweden2001In: Urban transport VII: urban transport and the environment for the 21st century / [ed] L.J. Sucharov, C.A. Brebbia, Southampton: WIT Press , 2001, p. 497-508Conference paper (Other academic)
  • 58. Salih, Isam
    et al.
    Bäckström, Mattias
    Örebro University, Department of Natural Sciences.
    Karlsson, Stefan
    Örebro University, Department of Natural Sciences.
    Lund, Eva
    Pettersson, Håkan B. L.
    Impact of fluoride and other aquatic parameters on radon concentration in natural waters2004In: Applied Radiation and Isotopes, ISSN 0969-8043, E-ISSN 1872-9800, Vol. 60, no 1, p. 99-104Article in journal (Refereed)
    Abstract [en]

    Radon (222Rn) accumulation in water in relation to stable elements was studied for the purpose of determining factors influencing the transfer of 222Rn to and from water. In 72 groundwater samples, 222Rn and about 70 analytical parameters were analysed using radiometric and ICP-MS techniques. Using multivariate statistics (partial least squares), it was observed that 222Rn has a positive correlation with fluoride and uranium. The correlation with fluoride was further investigated by a laboratory time-scale experiment to measure the emanation of 222Rn from water as a function of fluoride, pH and carbonate. The transfer of 222Rn from water was measured by continuous monitoring in air in a closed loop set-up. It was observed that fluoride in water adhere or trap 222Rn preferably in acidic water (pH 3). It is suspected that natural physical processes (such as diffusion and microbubble phenomenon) are less effective to transport 222Rn in the presence of fluoride.

  • 59.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Chemical association and mobility of trace elements in 13 different fuel incineration bottom ashes2016In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 172, p. 105-117Article in journal (Refereed)
    Abstract [en]

    The release of trace elements from waste incineration bottom ash is problematic during utilization/landfilling. Thirteen bottom ashes (from various waste fuels and wooden/mixed wooden fuel) were investigated with respect to the total content, leaching behaviour by standard leaching procedure (EN 12457-3), and chemical association of trace elements by sequential extraction. Results showed that the content of trace elements in household/or industrial waste bottom ashes were of high level in comparison to in wooden/mixed wooden fuel/mixed wooden waste ashes. Type of fuel being treated greatly impacts the total inventory of trace elements. On average, trace element content in 13 ashes followed the decreasing order; Cu > Zn > Pb > Cr > Ni > Sb > As. In this study the average total content of Zn, Pb, Cu and Cr was higher in grate bottom ash treating household/industrial waste in comparison to fluidized boilers ash using same waste, however, there were too few data points and variation in data was large. By Standard leaching procedure, an excessive amount (more than disposal limit) of leached Cr, Pb, Sb and Cu (mostly in household/industrial waste ash) was observed in 6, 5, 5 and 4 of the 13 samples, respectively. Correlation coefficients (r) found between total and water leachable contents for Cu, Sb and As were 0.8, 0.7 and 0.6 respectively. Sequential extraction indicated that residual was the major fraction mostly, however, considerable amounts of trace elements had the potential to leach out. A large fraction of arsenic (57% based on average values) in 5 samples (mostly in waste/virgin wood and mixed wooden waste/fuel) and Zn (49% based on average values) in 4 of 13 samples (mostly household/or industrial) were found in the fractions that are easily available (acid soluble and exchangeable). Further, a considerable amount of Cu in 4 samples were found associated with the organic-bound phase. Dissolved organic matter might play an important role in leaching of Cu during utilization/landfilling. Moreover, principal component analysis (PCA) showed that fuel type affects the association of trace elements in bottom ash. Amounts of labile trace elements in wooden/mixed wooden fuel/waste bottom ashes were comparatively lower than other fuel bottom ashes. None of the samples exceeded the limit of disposal with respect to DOC leaching while chlorine in two and sulphate in three samples (household/industrial) exceeded limit. LOI (550 °C) values were higher for bottom ash from grate facilities probably due to no-pre-treatment of the waste fuel. While comparatively low values of LOI (1 000 °C) in few samples implies that the oxidation might have outweighed the loss of carbonates.

  • 60.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Chemical association and mobility of trace elements in 13 different fuel incineration fly ashes2015In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 165, p. 193-204Article in journal (Refereed)
    Abstract [en]

    The migration of trace elements from waste incineration fly ash is problematic during utilization/ landfilling. This study investigated the chemical association and potential mobility of trace elements in fly ashes originating from incineration of different fuels [virgin wood, recovered waste wood (RWW), mixed wooden fuel/waste, household, industrial, and mixed waste]. Fly ashes were characterized for total content of trace elements, chemical association by sequential extraction and leaching behaviour by standard leaching method (EN 12457-3). Results showed that average total content of trace elements in 13 fly ashes decreased in the order Zn > Cu > Pb > Sb > Cr > As > Cd. Sequential extraction results indicated that overall, Cd, Pb, Zn, Cu and Sb were the most mobile elements and excessive leaching was associated with high content of acid exchangeable fractions. Sequential extraction showed thatthe average percentage of trace elements in labile and stable fractions for all 13 fly ashes decreased in the order:Cd > Cu > Sb > Zn > As > Pb > Cr (ion-exchangeable), Pb > Zn > Sb > Cd > Cu > As > Cr(acid soluble),Cr > As > Pb > Sb > Cu > Zn > Cd (residual). The standard leaching procedure of ashes indicated that the leached amount of Pb in all samples, Zn in 7 while Cu in 6 (out of 13) samples, respectively, exceeded the regulatory level for disposal. Moreover, principal component analysis (PCA) showed that fuel type affects the chemical association of trace elements in fly ash. Further, risk assessment code (RAC) suggested that most of fly ashes presented very high risk due to high RAC values for Cd, Zn, Cu and Sb.

  • 61.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Distribution and leaching characteristics of trace elements in ashes as a function of different waste fuels and incineration technologies2015In: Journal of Environmental Sciences(China), ISSN 1001-0742, E-ISSN 1878-7320, Vol. 36, no 1 Oct., p. 9-21Article in journal (Refereed)
    Abstract [en]

    Impact of waste fuels (virgin/waste wood, mixed biofuel (peat, bark, wood chips) industrial, household, mixed waste fuel) and incineration technologies on partitioning and leaching behavior of trace elements has been investigated. Study included 4 grate fired and 9 fluidized boilers. Results showed that mixed waste incineration mostly caused increased transfer of trace elements to fly ash; particularly Pb/Zn. Waste wood incineration showed higher transfer of Cr, As and Zn to fly ash as compared to virgin wood. The possible reasons could be high input of trace element in waste fuel/change in volatilization behavior due to addition of certain waste fractions. The concentration of Cd and Zn increased in fly ash with incineration temperature. Total concentration in ashes decreased in order of Zn > Cu > Pb > Cr > Sb > As > Mo. The concentration levels of trace elements were mostly higher in fluidized boilers fly ashes as compared to grate boilers (especially for biofuel incineration). It might be attributed to high combustion efficiency due to pre-treatment of waste in fluidized boilers. Leaching results indicated that water soluble forms of elements in ashes were low with few exceptions. Concentration levels in ash and ash matrix properties (association of elements on ash particles) are crucial parameters affecting leaching. Leached amounts of Pb, Zn and Cr in > 50% of fly ashes exceeded regulatory limit for disposal. 87% of chlorine in fly ashes washed out with water at the liquid to solid ratio 10 indicating excessive presence of alkali metal chlorides/alkaline earths.

  • 62.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Leaching of Zn, Cu and Pb from oxidised sulphidic mine waste as a function of temperature, L/S ratio and leaching reagents2013In: Goldschmidt, 2013Conference paper (Refereed)
  • 63.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Trace element partitioning in ashes from boilers firing pure wood or mixtures of solid waste with respect to fuel composition, chlorine content and temperature2014In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 34, no 12, p. 2505-2519Article in journal (Refereed)
    Abstract [en]

    Trace element partitioning in solid waste (household waste, industrial waste, waste wood chips and waste mixtures) incineration residues was investigated. Samples of fly ash and bottom ash were collected from six incineration facilities across Sweden including two grate fired and four fluidized bed incinerators, to have a variation in the input fuel composition (from pure biofuel to mixture of waste) and different temperature boiler conditions. As trace element concentrations in the input waste at the same facilities have already been analyzed, the present study focuses on the concentration of trace elements in the waste fuel, their distribution in the incineration residues with respect to chlorine content of waste and combustion temperature. Results indicate that Zn, Cu and Pb are dominating trace elements in the waste fuel. Highly volatile elements mercury and cadmium are mainly found in fly ash in all cases; 2/3 of lead also end up in fly ash while Zn, As and Sb show a large variation in distribution with most of them residing in the fly ash. Lithophilic elements such as copper and chromium are mainly found in bottom ash from grate fired facilities while partition mostly into fly ash from fluidized bed incinerators, especially for plants fuelled by waste wood or ordinary wood chips. There is no specific correlation between input concentration of an element in the waste fuel and fraction partitioned to fly ash. Temperature and chlorine content have significant effects on partitioning characteristics by increasing the formation and vaporization of highly volatile metal chlorides. Zinc and cadmium concentrations in fly ash increase with the incineration temperature.

  • 64.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Uranium in 31 Swedish ashes – differences between boiler type and fuels2015In: Uranium – Past and Future Challenges / [ed] Merkel, B.J. and Arab, A., Springer, 2015, p. 745-750Conference paper (Refereed)
    Abstract [en]

    From 14 Swedish boilers (grate fired as well as fluidized bed) 31 different ashes were collected and analysed for uranium. Uranium concentrations ranged from 0.32 to 22 mg/kg dw. Average uranium concentration in the bottom ash and fly ash was 1.3 and 2.7 mg/kg dw, respectively, indicating that uranium in the fuel is quite volatile during combustion. Highest concentration of uranium was found in a fly ash from a boiler burning peat indicating that peat is a natural source of uranium.

  • 65.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Waste incineration: impact of input waste fuel composition on trace element distribution and chemical speciation in fly and bottom ashesArticle in journal (Refereed)
  • 66.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Waste incineration: impact of input waste fuel composition on trace element distribution and chemical speciation in fly and bottom ashes2015Conference paper (Refereed)
    Abstract [en]

    Incineration process for waste to energy is a widely developed method for solid waste management in Sweden and all over the world. In addition to its unique benefits of mass and volume reduction of waste, it can also provide electricity and/or heat. In Sweden 48% of household waste, 40% of industrial waste and 75% of recovered waste wood (RWW) (construction and demolition) are treated through incineration. In order to avoid environmental concerns and operational problems posed by incineration by-products (fly ash, bottom ash), it is important to understand that how trace element partitioning respond to the changes in waste composition. In this study, Influence of input waste fuel composition and chlorine content on trace element distribution in solid waste (RWW, industrial waste, RWW mixed with bark & sludge and mixed household & industrial waste) incineration fly and bottom ashes were studied. Further, chemical speciation of trace elements in resulting fly/bottom ashes was investigated by sequential extraction. Results indicate that Zn, Cu, Pb and Cr are the dominating trace elements in the waste fuel and ashes. Most part of high and medium volatile trace elements such as Cd, Pb, Zn, Sb and As were transferred to fly ash for pure RWW / industrial waste incineration in fluidized boilers. Overall, As and Cd seems to show increased transfer to fly ash with the increase in input content of these elements in the waste fuel, while low volatiles Cu and Cr showed decrease in transfer to fly ash with input content. Overall, Cd was partitioned mostly in the fly ash in all cases during incineration, most probably because of vaporization, condensation on fly ash particles and adsorption mechanisms. While 2/3 or more of Zn and Pb also transferred to fly ash. Low volatiles Cu and Cr stayed mainly in the bottom ash except in a few fluidized boilers operation that might be attributed to particle entrainment or turbulence. Increased chlorine in the waste fuel feed increased the trace element transfer to fly ash especially for Zn and Pb by forming their metal chlorides that are highly volatile. Sequential extraction results and risk assessment code showed that Zn and Pb in RWW, Cd in industrial waste, Pb, Cu and Cd in mixed household/industrial waste while Zn, Cd in mixed biofuel waste fly ash were posing high risk to the environment on utilization/landfilling. Further speciation results indicated that in RWW bottom ash, arsenic was mainly (around 50%) present in mobile fractions (ion exchangeable and acid soluble). While in mixed household & industrial waste bottom ash, 65% of Cu was bound to the oxidizable fraction that indicates the role of organic matter on leaching. Moreover, bottom ash from incineration of industrial waste or mixed household/industrial waste contained higher amounts (as compared to biofuel incineration bottom ashes) of trace elements such as that of Zn, Cu, Cr and Sb in labile fractions An increased input concentration of certain trace elements, such as Zn when firing pure RWW or mixed biofuel and chlorine while firing mixed waste or industrial waste, caused increased concentration in fly ash. It might also boost the deposition and corrosion problems. So it is suggested to keep input metal content and chlorine concentrations as low as possible

  • 67.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Sartz, Lotta
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Chemical leaching of Zn, Cu and Pb from oxidized sulfidic mining waste followed by stabilization using green liquor dregManuscript (preprint) (Other academic)
  • 68.
    Saqib, Naeem
    et al.
    Örebro University, School of Science and Technology.
    Sjöberg, Viktor
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Flotation tailings as a copper resource - Extraction and characterization through chemical leachingManuscript (preprint) (Other academic)
  • 69. Sartz, L.
    et al.
    Bäckström, Mattias
    Örebro University, Department of Natural Sciences.
    The behaviour of barium, strontium, aluminium, chromium and molybdenum when leaching fly ash with acid rock drainage2008In: ICAM 2008: Ninth international congress for applied mineralogy, 2008, p. 357-364Conference paper (Other academic)
    Abstract [en]

    Acid rock drainage (ARD), commonly found in vicinities of sulfidic mines, possess properties capable of widely affecting the surrounding environment by acidification and heavy metal pollution. In most ARD treatments, various alkaline sources are used to neutralise the acid produced. Utilisation of highly alkaline fly ashes instead of raw materials is a cost-effective alternative, which lately have become increasingly popular. In laboratory batch experiments, neutralising capacity of fly ash was studied during 20 days. ARD was added to the fly ash once a day, for each increment the liquid to solid ratio (L/S ratio) was increased. At an early stage of the experiment (day 6, L/S ratio 12), the concentration of barium in solution unexpectedly increased by a factor of 50 (from 200 to 10 000 Όg·1-1). This high concentration also sustained the following two days (L/S ratios 14 and 16) before dropping to the original level. pH showed a slight increase during these observations (pH 12.4-12.7). The phenomenon was also observed in a parallel and identical series. In addition to barium, aluminium and strontium clearly increased in the same manner, however not as much as barium. Furthermore, concentrations of chromium and molybdenum noticeably decreased at these distinct L/S ratios (12, 14 and 16). The behaviour of barium and subsequently strontium, aluminium, chromium and molybdenum is only partially understood. The decrease of chromium and molybdenum is suggested to be due to incorporation into the interlayer regions of hydrocalumite (Ca4Al2(OH)12(OH) 2·6H2O), replacing the hydroxide groups, which also explains the increase in pH. Moreover, the increase of barium, strontium and aluminium could be attributable to dissolution of the silicate mineral celsian (Ba,Sr(Al2Si2O8)). Alternatively, barium and strontium increase could be explained by dissolution of a Ba,Sr(SO 4)-solid solution and aluminium increase by dissolution of hydrocalumite or ettringite.

  • 70.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Chemical stabilization of historic mine waste using alkaline paper mill by-products: batch mixing experimentsManuscript (preprint) (Other academic)
    Abstract [en]

    Neutralization of acid-generating sulphidic mine waste by mixing with three alkaline paper mill by-products (lime mud, green liquor dregs and fly ash) were studied in batch experiments. An initial liquid/solid (L/S) ratio of 10 was used, where after the mixtures were diluted at four occasions (corresponding to L/S 12, 14, 16 and 18).

    pH in the control was 3.3 to 3.1 (slightly decreasing with time/leach day) while pH in the amended systems was increased with three to four pH-units compared to the control. An amendment of 5 % was sufficient to increase pH to 7 and slightly above. A mixture of alkalinities from lime mud and fly ash (carbonate and hydroxide), did not increase pH more than the pure lime mud amendment, except at a very high amendment (50 %).

    Trace element immobilizations (Cu, Zn, Cd, Pb) were almost quantitative: Concentrations in amended systems were decreased compared to the control with more than 97 %. Immobilization of lead was pH-dependent, while zinc and copper did not show such strong correlation with pH. The main trace element immobilization mechanism was probably sorption onto formed iron oxy(hydr)oxides and/or coprecipitation.

    Elements that might increase due to amendment of the alkaline materials were chromium, vanadium and molybdenum. Chromium was present at highest concentrations in the green liquor dreg, and leaching of chromium (around 600 µg/l) was also observed from this material. Leached chromium concentrations in the green liquor dreg amended systems were however decreased due to lowered pH and Cr(OH)3 precipitation.

  • 71.
    Sartz, Lotta
    et al.
    Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Chemistry and environmental science research as a part of education: An example from Sweden2014In: 1st International Congress and Exhibition on Current Trends on Science and Technology Education (SCITEED 2014) / [ed] Oral, A.Y. and Bahsi, Z.B., Curran Associates, Inc., 2014, p. 27-32Conference paper (Refereed)
  • 72.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kumla, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Development of a low-tech treatment for neutral mine water: a case study2016In: Mining Meets Water: Conflicts and Solutions / [ed] Drebenstedt, C. & Paul, M., Freiberg, Germany: TU Bergakademie Freiberg, Institute of Mining and Special Civil Engineering , 2016, p. 913-918Conference paper (Refereed)
    Abstract [en]

    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 %.

  • 73.
    Sartz, Lotta
    et al.
    Bergskraft Bergslagen, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Impact of temperature on weathering rates: a long term kinetic study on waste rock from Bergslagen, Sweden2013In: Annual International Mine Water Association Conference: Reliable Mine Water Technology / [ed] Brown, A.; Figueroa, L. & Wolkersdorfer, Ch., Colorado, USA: IMWA , 2013, p. 463-469Conference paper (Refereed)
    Abstract [en]

    To assess the impact of different climatic conditions four weathering systems with waste rock from Bergslagen, Sweden, were followed. Secondary weathering products (ferrous and ferric sulphates and (oxy)hydroxides) on pyrite surfaces can slow down oxidation rates. It was investigated if repeated freezing/thawing could have an effect on the stability of the secondary product layer. After 90 weeks of weathering, freezing/thawing had not enhanced weathering rates, not even in combination with warm, humid air. Highest weathering rates were unexpectedly found in a reference system constantly kept at room temperature, and not in the more forceful humidity cell system.

  • 74.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Laboratory mixing of oxidized mine waste with different alkaline by-products (LD-slag, lime kiln dust and fly ash)Manuscript (preprint) (Other academic)
    Abstract [en]

    Neutralization and metal removal efficiency were studied for mixtures of alkaline waste materials and oxidized mine waste. Leaching of the mixtures were performed during 65 days at an L/S ratio of 10-18.

    It was found that as pH increased the trace element concentrations from the mine waste (mainly Cd, Cu, Pb and Zn) were immobilized through sorption and partly precipitation at higher pH. However, as the amount of alkaline amendments increased leaching of anionic trace elements (Cr, Mo, Se and V) from the alkaline by-products were noticed. For LD leaching of vanadium was particularly significant and showed increasing concentrations with time. It was also found that the anionic trace elements had a maximum leaching at pH around 10-11, where sorption became important. It is thus important to keep pH below 10 in order to minimize the anionic leaching. Optimum pH for immobilization of trace elements from the mine waste was therefore found to be between 8 and 10. Optimum pH can be achieved by addition of around 20-30 % fly ash or by 5-10 % LD or LKD. For the highly alkaline materials there is a significant risk that the resulting pH from a remediation will be higher than 10, which will lead to increased leaching of several anionic trace elements. For the fly ashes the problem is the opposite with risk of obtaining a pH to low to immobilize especially zinc.

  • 75.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Long-term leaching of fly ash with ARD: pH-dependent accumulation and release of trace elementsManuscript (preprint) (Other academic)
    Abstract [en]

    In most ARD treatments, various alkaline sources are used to neutralize the acid produced. Utilization of highly alkaline fly ashes instead of raw materials is a cost-effective alternative, which lately have become increasingly popular.

    In laboratory batch experiments, neutralizing capacity for fly ash was studied during 20 days in two parallel series. ARD was added to fly ash once a day, for each increment the liquid to solid ratio (L/S ratio) was increased (final L/S around 3 000).

    At an early stage of the experiment (L/S ratio 12), the concentration of barium in solution unexpectedly increased from 200 to 10 000 µg/l. pH showed a slight increase during these observations (pH 12.4-12.7). Furthermore, concentrations of chromium and molybdenum noticeably decreased at these distinct L/S ratios. The decrease of chromium and molybdenum is suggested to be due to incorporation into the interlayer regions of hydrocalumite (Ca4Al2(OH)12(OH)2∙6H2O), replacing the hydroxide groups, which also explain the increase in pH.

    Trace elements (Cd, Cu, Pb and Zn) from the added ARD were effectively removed from the solution (93-96 %) and were not released until pH dropped below 7. Major mechanism behind the immobilization of trace elements is sorption onto newly formed HAO/HFO.

    Large differences were seen between leaching with different leaching media (distilled water or ARD), why the use of site-specific materials and reagents are crucial in experiments evaluating possible use in field applications.

  • 76.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Reclamation of historical mine waste using alkaline by-products2007In: Northern Latitudes Mining Reclamation Workshop, Juneau, Alaska, USA, 15-17 May, 2007, 2007, p. 10 pages-Conference paper (Refereed)
  • 77.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Treatment of acidic and neutral metal-laden mine waters with bone meal filters2012In: Mine Water and the Environment / [ed] McCullough, C.D., Lund, M.A. and Wyse, L, International Mine Water Association (IMWA) , 2012, p. 643-650Conference paper (Refereed)
  • 78.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Treatment of Acidic and Neutral Metal-Laden Mine Waters with Bone Meal Filters2013In: Mine Water and the Environment, ISSN 1025-9112, E-ISSN 1616-1068, Vol. 32, no 4, p. 293-301Article in journal (Refereed)
    Abstract [en]

    Bone meal was used to treat two different mine waters: acidic (pH 4.5) mine water containing high concentrations of Fe and Al and neutral/slightly alkaline (pH 7) mine water. Original primary contaminants in both waters were Pb and Zn. The contaminants were dissolved in the acidic mine water and mostly suspended in the neutral mine water. Flow through the filter treating the acidic mine water was relatively low (0.1 L/min), but increased towards the end of the test period. Removal of Pb and Cu was very good in the acidic mine water (around 80 %); removal of Zn was slightly less (60 %) due to the final pH (approximate to 6-6.5). Flow through the filter treating the neutral mine water was initially significantly higher (5 L/min) and the removal of Pb and Zn was less compared to the acidic mine water (50 % for Pb and 35 % for Zn). The major reason for the difference in metal removal in the two mine waters was the difference in Fe and Al sorption sites, flow rate, and pH; in order for the bone meal to dissolve and form metal phosphate, the pH has to be <7.

  • 79.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kumla, Sverige.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    On the neutralisation of ARD and acid generating waste rock by different alkalinity sources: carbonate and/or hydroxide2010In: Mine water & innovative thinking: proceedings 2010 / [ed] Wolkersdorfer, C. and Freund, A., Nova Scotia, Canada: Cape Breton University Press , 2010, p. 263-266Conference paper (Refereed)
    Abstract [en]

    Six alkaline waste materials were tested for their neutralising capacity and metal immobilisation ability as amendments to a weathered waste rock. Two of the materials were of carbonate-type: lime mud (LM) and green liquor dreg (GLD) and four were of hydroxide-type: lime kiln dust (LKD), LD-slag (LD), carbonated fly ash (CFA) and a fresh fly ash (FFA). pH achieved by carbonate and ARD reactions (approximately 6) is too low to ensure quantitative sorption of e.g. Zn and Cd. Hydroxide neutralisation reactions however result in higher pH, but lower alkalinity.

  • 80.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Alkaline by-products as amendments for stabilization and neutralization of oxidized sulphidic mine waste deposits2010In: 34th British Columbia Mine Reclamation & 35th CLRA/ACRSD National Conference, 2010, p. 10 pages-Conference paper (Refereed)
    Abstract [en]

    Stabilization of oxidized sulphidic mine waste deposits with alkaline by-products could be a way of controlling ARD. Mixtures of alkaline by-products (10% by volume) and oxidized waste rock have been studied during six months in 30 L experimental drums. Alkaline by-products are: lime mud (LM), green liquor dreg (GLD), lime kiln dust (LKD), LD slag (LD), water work granules (WWG), carbonized fly ash (FAE) and fresh fly ash (FAF). The experiments are fed with water once a week to imitate natural precipitation.

    pH of the reference (no alkaline amendment) is below 3 and trace metal concentrations are 2000 mg/l, 4 mg/l and 1 mg/l for Zn, Cd and Pb respectively. LKD, LM and LD amended systems (pH 6.7-7.5) are the most efficient for Cd- and Zn-removal (reduction at least 99 % compared to the reference), while GLD (tap pH 6.5) is the most efficient for Pb-removal (99 % reduction compared to the reference). FAE amended system only reaches pH around 5 and accordingly trace metal reduction is rather low. Geochemical simulations using PHREEQC indicate equilibrium with otavite and smithsonite in the WWG and GLD systems, whereas cerrusite is at equilibrium in the LKD, WWG and GLD systems.

  • 81.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Paper mill by-products and fly ash as amendments to oxidized waste rock: neutralization and trace metal reduction in a meso-scale field studyManuscript (preprint) (Other academic)
    Abstract [en]

    Remediation of oxidized mine waste is often hampered by the risk of reductive dissolution of ferric iron phases and the resulting release of trace elements. In order to partly avoid this problem the oxidized mine waste can be amended with an alkaline material. In this meso-scale experiment with 7 different amended systems and a control an oxidized waste rock was mixed with several alkaline by-products and leachates were collected for 44 months. Results show that pH in the amended systems increased between 1.1 and 2.2 pH units compared to the untreated reference (pH 4.4). The increase in pH resulted in a significant decrease in trace element concentrations, averaging a concentration reduction around 97 %. Sorption was probably the main reduction mechanism.

    Flow rate measurements in the different systems showed a strong correlation between pH and the flow rate. It was concluded that the type of alkaline material and the number of alkaline layers were of less importance than the flow rate when it came to quality of the leachates. However, fly ashes were found in all the best performing systems. Longer residence time clearly improves the quality of the leachates. When it comes to comparison of the different systems it seems that systems containing fly ashes performed best. Least effective systems contained green liquor dregs and amendments with too little fly ash. It is clear that alkaline materials can be used in order to reduce the leaching of trace elements from historical mine waste deposits.

  • 82.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Law, Psychology and Social Work.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Effect of pH and time on the release of vanadium from LD -slag2009Conference paper (Refereed)
  • 83.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    From bench to field: A stepwise method towards full scale remediation of historic mine sites2009In: 8th International Conference on Acid Rock Drainage (ICARD) and Securing the Future: Mining, Metals & the Environment in a Sustainable Society 2009, 2009, p. 1207-1216Conference paper (Refereed)
  • 84.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Leaching of lime kiln dust and LD-slag with ARD in a sequential batch experiment2010Manuscript (preprint) (Other academic)
    Abstract [en]

    Treatment of ARD in a reactive barrier or an alkaline filter prior to release to the recipient is a desired and often suggested alternative. Alkaline candidate materials for the purpose that are cheap are by-products such as fly ash, lime kiln dust and different steel slags. An experiment was carried out where two highly alkaline by-products (LD slag and lime kiln dust) were exposed to a real ARD in sequential batch design.

    It was found that the buffering capacity was high enough in both materials in order to neutralize the added ARD even if large portions of the total buffering capacity was washed out during the experiment. Washing out of alkalinity is a greater problem for oxide/hydroxide materials than it is for carbonate dominating materials. Calculations indicated that the buffering capacity in the LKD would last at least until L/S 3 000 while it would last approximately until L/S 1 000 for LD slag. Lack of buffering capacity is thus not the major problem with the materials, but rather the lack of capacity for trace element immobilization. Including sorption onto HFO and HAO and precipitation of different hydroxides and carbonates the already immobilized trace elements from the added ARD started to be remobilized around pH 8. Below pH 8 concentrations increased rapidly due mainly to desorption and was soon found to be higher than in the added ARD.

    Some of the divalent elements (Mg and Mn) were also found to be controlled by their hydroxides at high pH and at circumneutral pH by their carbonates. This results in higher concentrations at lower pH (below 10) since the carbonates are more soluble than the hydroxides.

    It is important to characterize the used alkaline by-products at the expected chemical conditions in order to be able to assess potential trace element leaching (most likely anionic elements such as vanadium and chromium).

  • 85.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Mixing of acid rock drainage with alkaline ash leachates: formation of solid precipitates and pH-buffering2010Manuscript (preprint) (Other academic)
    Abstract [en]

    Three metal-rich and acidic mine waters (from Bersbo and Ljusnarsberg, Sweden) were mixed with alkaline fly ash leachates in various proportions, representing a pH-titration. The changes in pH, as well as the loss of metals in solution due to precipitation of solid phases, were followed. Mineral equilibria and changes in pH and alkalinity were simulated with the geochemical code PHREEQC using the MINTEQv4 database, and comparisons between measured and simulated pH-responses were made.

    The formation of solid precipitates corresponded to fairly well-defined pH-buffering regions, reflecting the composition of the mine waters (notably the levels of Fe, Al and Mn). For the mine waters not dominated by iron the precipitation of zinc had a distinct buffering effect at near-neutral pH. The formation of solid magnesium phases (carbonate, as well as hydroxide) was indicated at high pH (above 9), but no formation of solid calcium phases despite high sulfate levels. The phases that precipitate were various amorphous mixtures, mostly of the metals Fe, Al, Mn, Zn and Mg.

    For the iron-rich mine water, pH was poorly simulated with a simple MIX-model, while alkalinity predictions agreed reasonably well with measured data. For the aluminum-rich mine waters the simulated pH-responses agreed well with the measurements.

  • 86.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Mixing of acid rock drainage with alkaline leachates: Formation of solid precipitates and pH-buffering2016In: Mine Water and the Environment, ISSN 1025-9112, E-ISSN 1616-1068, Vol. 35, no 1, p. 64-76Article in journal (Refereed)
    Abstract [en]

    Three metal-rich, acidic mine waters (from Bersbo and Ljusnarsberg, Sweden) were mixed with alkaline fly ash leachates in various proportions, representing a pH titration. Changes in pH and the loss of metals in solution due to precipitation of solid phases were tracked. Mineral equilibria and changes in pH and alkalinity were simulated using the geochemical code PHREEQC and the MINTEQv4 database, and the measured and simulated pH responses were compared. The formation of solid precipitates corresponded to fairly well-defined pH-buffering regions, reflecting the mine water compositions (notably the levels of Fe, Al, and Mn). Zn precipitation had a distinct buffering effect at near-neutral pH for the mine waters not dominated by iron. The formation of solid Mg phases (carbonate, as well as hydroxide) was indicated at high pH (above 9), but not formation of solid Ca phases, despite high sulfate levels. The phases that precipitated were various amorphous mixtures, mostly of the metals Fe, Al, Mn, Zn, and Mg. For the Fe-rich mine water, pH was poorly simulated with a simple MIX model, while alkalinity predictions agreed reasonably well with measured data. For the Al-rich mine waters, the simulated pH responses agreed well with the measurements. In an additional step, geochemical simulations were performed where selected proxy phases for major elements were forced to precipitate; this significantly improved the pH and alkalinity predictions. This approach may be more efficient than performing mixing experiments and titrations.

  • 87.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Stabilisation of acid-generating waste rock with alkaline by-products: Results from a meso-scale experiment2009In: Securing the Future and 8th ICARD, 2009, p. 10 pages-Conference paper (Refereed)
  • 88.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Strategy for instant neutralisation and metal immobilisation in ARD2010In: Mine water and innovative thinking: proceedings 2010 / [ed] Christian Wolkersdorfer, Antje Freund, Nova Scotia, Canada: Cape Breton University Press , 2010, p. 267-270Conference paper (Refereed)
    Abstract [en]

    For ARD filters, reactive barriers are often the methods of choice. Some problems are recognised though; iron precipitation cause hydraulic changes and inhibition of neutralising phases. Instead of filter/barrier installation alkalinity is suggested to be added in an aqueous phase (leach beds). Addition of a highly alkaline solution to different ARD results in a rapid, almost instant neutralisation, precipitation of metals (Fe, Al) as well as almost quantitative coprecipitation and sorption of trace metals at near neutral pH. Generation of alkalinity on-site, added to ARD as an aqueous phase, would be a fast and simple ARD treatment method.

  • 89.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Sjöberg, Viktor
    Örebro University, School of Science and Technology.
    ARD treatment in sequential filter sections: efficiency of different alkaline waste materials2010In: Mine water and innovative thinking: proceedings 2010 / [ed] Christian Wolkersdorfer, Antje Freund, Nova Scotia, Canada: Cape Breton University Press , 2010, p. 271-274Conference paper (Refereed)
    Abstract [en]

    Six alkaline waste materials are tested as potential filter materials for ARD treatment. The study is an ongoing project since 2.5 years on a mine waste remediation test field in  opparberg, Sweden. The filters (0.5 m3) are operating under field conditions and general parameters (pH, electric conductivity, redox potential (Eh), alkalinity, acidity and sulphate) are measured immediately after sampling in a mobile laboratory. The reactive (alkaline) materials are followed by other filter materials in sequence with non-reactive support materials, to ensure iron/aluminum precipitation and trace metal sorption.

  • 90.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kumla, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Sädbom, Stefan
    Bergskraft Bergslagen AB, Kumla, Sweden.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Alkaline by-products to ameliorate oxidized sulphidic mine waste and ARD2010In: Proc. EU Mine Drainage Research Exchange Conf. PADRE, June 11, Freiberg, Germany, 2010, p. 1 p-Conference paper (Refereed)
  • 91.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Sjöberg, Viktor
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Successive neutralization, precipitation and trace metal immobilization in meso-scale filters for ARD treatmentManuscript (preprint) (Other academic)
    Abstract [en]

    Six alkaline by-products were studied in reactive filters (3×0.4 m3) built on the historic mine site Ljusnarsbergsfältet, Kopparberg, Sweden. Each filter was made out of three connected sections in a sequence (neutralization – oxidation (precipitation) – sorption). Total buffering capacity of the alkaline materials was found to have a minor impact on their respective performances. Other chemical and physical circumstances were more important, e.g. carbonation, iron precipitation and preferential flow path formations. A combination of fresh fly ash and lime mud had similar chemical responses as a carbonated fly ash. These filters were also the worst performers, considering overall trace element immobilizations.

    No particular differences were found between two different passive adsorbents in the oxidation stage, where iron and aluminum were intended to precipitate and act as sorbent phases for other elements: Cu, Zn, Cd, and Pb. In general it was found that highly alkaline materials containing alkalinities as CaO/Ca(OH)2 were superior to materials with carbonate alkalinity.

  • 92.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Sädbom, Stefan
    Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Applicability and suitability of different alkaline by-products in historic mine sites remediation2012In: 9th International Conference on Acid Rock Drainage (ICARD 2012) / [ed] Price, W.A., Hogan, C. and Tremblay, G., Mine Environment Neutral Drainage ( MEND ) , 2012, p. 682-693Conference paper (Refereed)
  • 93.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kumla, Sweden.
    Hamilton, Ian
    Econova Recycling AB, c/o Alfred Nobel Science Park, Örebro Sweden.
    Macsik, Josef
    Ecoloop AB, Stockholm, Sweden.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Luleå, Sweden.
    Sädbom, Stefan
    Bergskraft Bergslagen AB, Kumla, Sweden.
    Westin, Gunnar
    RISE Processum AB, Örnsköldsvik, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kumla, Sweden.
    Green Liquor Dregs from Pulp and Paper Industry used in Mine Waste Management: a Symbiosis Project (GLAD) between two Swedish Base Industries2017In: Mine Water & Circular Economy / [ed] Wolkersdorfer, C., Sartz, L., Sillanpää, M. and Häkkinen, A, Lappeenranta, Finland: Lappeenranta University of Technology , 2017, Vol. II, p. 862-868Conference paper (Refereed)
    Abstract [en]

    Mining has been and still is an important industry in Sweden. Leaching from sulfidic mining waste is however a serious environmental issue that can bring acidity and metals in solution. Simultaneously, green liquor dreg (GLD) with potential to decrease oxygen transport to the waste and neutralize acid leachate, is generated by the pulp and paper industry and deposited in landfills. The aim of the project is to promote valorisation of GLD, identify hinders and create a database providing information about the material and its variability to enhance establishment of circular economy for the pulp and paper mill waste.

  • 94.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Larsson, Erik
    Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Alkaline treatment of ARD: carbonate and hydroxide alkalinities in sequence2012In: 9th International Conference on Acid Rock Drainage (ICARD 2012) / [ed] Price, W.A., Hogan, C. and Tremblay, G, Ontario, Kanada: Golder Associates Ltd. , 2012, p. 78-88Conference paper (Refereed)
  • 95.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Larsson, Erik
    Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Sädbom, Stefan
    Bergskraft Bergslagen AB, Kopparberg, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Weathering of waste rock in different climatic conditions: A kinetic freeze/thaw and humidity cell experiment2011In: Mine water: Managing the challenges: proceedings of the International Mine Water Association Congress 2011 / [ed] Rüde, T.R., Freund, A. and Wolkersdorfer, C., Aachen: RWTH , 2011, p. 453-456Conference paper (Refereed)
    Abstract [en]

    Ferrous and ferric sulphates and (oxy)hydroxides can grow on pyrite surfaces and slow oxidationrates. However, in northern climates, repeated freeze/thaw cycles can cause cracks, channeling and exposureof new surfaces. In the present study, weathering in a repeated freeze/thaw experiment was compared to aregular humidity cell experiment. Introductory results (after 17 weeks) show very small changes in pH for thefreeze/thaw system (pH around 5), while pH in reference and humidity cell systems decreased rapidly thefirst weeks (to around 4). An increase in electrical conductivity, sulphate and major ions was noticed in thetwo latter systems.

  • 96.
    Sartz, Lotta
    et al.
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kumla, Sweden.
    Sädbom, Stefan
    Bergskraft Bergslagen AB, Kumla, Sweden.
    Bäckström, Mattias
    Örebro University, School of Science and Technology. Bergskraft Bergslagen AB, Kumla, Sweden.
    Remediation of Historic Waste Rock by Injection of Green Liquor Dregs: Results From a Field Scale Trial, Gladhammar, Southern Sweden2018In: Mine Water: Risk to Opportunity / [ed] Wolkersdorfer, Ch., Sartz, L., Weber, A., Burgess, J. and Tremblay, G, Pretoria, South Africa: Tshwane University of Technology , 2018, Vol. II, p. 1124-1129Conference paper (Refereed)
    Abstract [en]

    Mining in Gladhammar, southern Sweden started in the 15th century, generating waste rock containing copper, cobalt, and arsenic. During remediation (2011) some waste rock was preserved, due to its geoscienti- c value, and placed on a geomembrane surface. Eventually, it became apparent that it had a substantial environmental impact (pH 3.8, Cu 96 mg/L, Co 21 mg/L). In 2017, green liquor dregs was injected in order to increase pH and decrease trace element mobility. Ten months a er injection pH was 8.3 and concentrations of copper and cobalt 1.3 mg/L and 1.1 mg/L, respectively. Evaluation will continue for at least five years.

  • 97. Skogsjö, Erika
    et al.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Barrier system for treatment of heavy metal drainage at Ranstad, Sweden2010In: Mine water & innovative thinking: Proceedings of the International Mine Water Association Symposium, 2010, Sydney, Nova Scotia, Canada, CBU Press , 2010, p. 275-278Conference paper (Refereed)
    Abstract [en]

    Alum shale was mined and processed (leaching with sulphuric acid for uranium recovery) atRanstad, Sweden, during 1965—69, and the shale residues were deposited on site. A barrier system fortreatment of leachates from the deposit was constructed in 1999: (1) Sedimentation pond (2) pre-treat-ment filter, and (3) final filter in sequence. Iron, Al and Mn were precipitated in section (2). Retention ofother elements (As, Cr, Co, Ni, Zn and U) is attributed to adsorption by precipitated iron and componentsin section (3). More than 90% of the Fe and As and 50% of the Cr, Cd, Zn and U were removed from theleachates.

  • 98.
    Stahre, Nanna
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Sartz, Lotta
    Örebro University, School of Science and Technology.
    Element leaching from green liqour dregs from 16 Swedish paper mills2019In: Sardinia_2019: 17th International Waste Management and Landfill Symposium, 30 sept-4 oct, 2019, Santa Margherita di Pula, Italy, 2019Conference paper (Other academic)
    Abstract [en]

    Green liquor dregs (GLD) is an alkaline by-product from the paper and pulp industry with a pH between 10 and 14. Today most of the produced GLD in Sweden are landfilled. In order to increase the utilization, the environmental performance needs to be determined. Samples were collected from 16 mills at 3 different times approximately 6 months apart, totalling 42 samples. Leaching was performed in two sequential steps at an L/S ratio of 2 and 8 on wet samples corresponding to 25 g DM. The liquid phases were analysed for pH, electrical conductivity, alkalinity, anions and element concentrations. Leaching of sodium and potassium were as expected very high but leaching of calcium was low. Chromium, nickel, copper, cadmium and zinc leaches generally less than ≤5% of total concentrations. Sodium and potassium are present in GLD as easily soluble salts that are easily washed out. Calcium leaching is restricted by calcite solubility resulting in little effect on short time buffering capacity, however, in the long term calcium minerals will affect the buffering capacity. For nickel, copper, cadmium and lead there are some soluble salts present in the GLD but most of the elements are probably solubility controlled. Geochemical calculations indicated hydroxides as solubility controlling phases for at least copper and in some cases also for lead. Leaching of zinc is to some extent solubility controlled which is indicated by the fact that the soluble concentrations is similar for both L/S 2 and L/S 8. When comparing the leached concentrations from GLD with concentrations from mining waste there is an environmental benefit even if the GLD is not inert. In conclusion, GLD is well suited to be used for treatment of acidic mining waste instead of being landfilled in non-hazardous and hazardous landfills.

  • 99.
    Uwayezu, Jean-Noel
    et al.
    Örebro University, School of Science and Technology.
    Yeung, Leo W. Y.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Sorption of PFOS isomers on goethite as a function of pH, dissolved organic matter (humic and fulvic acid) and sulfate2019In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 233, p. 896-904Article in journal (Refereed)
    Abstract [en]

    Understanding the distribution of PFOS isomers between the aqueous phase and goethite is crucial, since it is an abundant sorbent and thus may have a large influence on the mobility of PFOS. This study was conducted to understand the effects of pH, humic acid (HA), fulvic acid (FA) and sulfate on sorption of PFOS isomers. The results will increase the understanding about what parameters may control the fate and transport of PFOS in surface and ground water.

    The study was conducted by adding PFOS spiked water to a goethite slurry with different aqueous chemistry. Levels of total PFOS and PFOS isomers were quantified using an Ultra-Performance Liquid Chromatograph coupled to a triple quadrupole mass spectrometer. Results showed that sorption of PFOS was mainly dependent on pH; sorption decreased as pH increased. Presence of HA increased log K-d from 1.29 to 2.03, 1.76 to 1.92 and 1.51 to 1.96 at pH 5.50-7.50 for 3-/4-/4-PFOS, 6-/2-PFOS and L-PFOS, respectively. Changes in the aqueous chemistry also affected the behaviour of PFOS as the addition of Na2SO4 enhanced the sorption of PFOS. Results showed that L-PFOS was more readily sorbed to goethite at pH < 4.35 both in the presence and in the absence of humic or fulvic acids. At pH > 4.5 the 3-/4-/5-PFOS isomer group was more associated to goethite. Besides electrostatic interactions, which controlled the sorption of PFOS, this study indicate that the presence of dissolved humic substances in the aqueous phase enhances the sorption via hydrophobic mechanisms.

  • 100.
    Åhlgren, Kristina
    et al.
    Örebro University, School of Science and Technology.
    Bäckström, Mattias
    Örebro University, School of Science and Technology.
    Identification of major point sources in the severely contaminated alum shale area in Kvarntorp, Sweden2016In: Mining Meets Water – Conflicts and Solutions: IMWA 2016 in Leipzig, Germany, July 11–15, 2016 / [ed] Drebenstedt, C. & Paul, M., Freiberg: TU Bergakademie Freiberg, Institute of Mining and Special Civil Engineering , 2016, p. 377-382Conference paper (Refereed)
    Abstract [en]

    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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