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  • 1. Abderrazek, K.
    et al.
    Uheida, Abdusalam
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Seffen, M.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Srasra, N. Frini
    Srasra, E.
    Photocatalytic degradation of indigo carmine using [Zn-Al] LDH supported on PAN nanofibres2015In: Clay minerals, ISSN 0009-8558, E-ISSN 1471-8030, Vol. 50, no 2, 185-197 p.Article in journal (Refereed)
    Abstract [en]

    Zn-Al layered double hydroxides (LDH), before and after calcination, were tested for the removal of indigo carmine (IC) dye from solution. These LDH photocatalysts were characterized by powder x-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetry/differential thermogravimetry (TG/DTG), nitrogen physisorption at -196 degrees C, scanning electron microscopy (SEM) and diffuse reflectance spectrophotometry (DRS). The different photocatalysts were supported on polyacrylonitrile (PAN) nanofibres, so that filtration was unnecessary. The PXRD and FTIR analyses showed that the IC adsorption on c-Zn-Al-3-500 (LDH calcined at 500 degrees C) was enhanced by construction of the hydrotalcite matrix intercalated with the dye. The intercalation was clearly evidenced by the appearance of a peak at low degrees 2 theta values. All of the materials prepared exhibited photocatalytic activity, which for the c-Zn-Al-3-500 was comparable to that of commercial PAN-supported ZnO nanoparticles (100% degradation after 180 min). Kinetic studies showed that the degradation of the IC followed a pseudo-first order rate. The high activity and the ease of both synthesis and separation processes rendered this photocatalyst a promising candidate for environmental remediation.

  • 2.
    Acuña, José
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Distributed thermal response tests: New insights on U-pipe and Coaxial heat exchangers in groundwater-filled boreholes2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    U-pipe Borehole Heat Exchangers (BHE) are widely used today in ground source heating and cooling systems in spite of their less than optimal performance. This thesis provides a better understanding on the function of U-pipe BHEs and Investigates alternative methods to reduce the temperature difference between the circulating fluid and the borehole wall, including one thermosyphon and three different types of coaxial BHEs.

    Field tests are performed using distributed temperature measurements along U-pipe and coaxial heat exchangers installed in groundwater filled boreholes. The measurements are carried out during heat injection thermal response tests and during short heat extraction periods using heat pumps. Temperatures are measured inside the secondary fluid path, in the groundwater, and at the borehole wall. These type of temperature measurements were until now missing.

    A new method for testing borehole heat exchangers, Distributed Thermal Response Test (DTRT), has been proposed and demonstrated in U-pipe, pipe-in-pipe, and multi-pipe BHE designs. The method allows the quantification of the BHE performance at a local level.

    The operation of a U-pipe thermosyphon BHE consisting of an insulated down-comer and a larger riser pipe using CO2 as a secondary fluid has been demonstrated in a groundwater filled borehole, 70 m deep. It was found that the CO2 may be sub-cooled at the bottom and that it flows upwards through the riser in liquid state until about 30 m depth, where it starts to evaporate.

    Various power levels and different volumetric flow rates have been imposed to the tested BHEs and used to calculate local ground thermal conductivities and thermal resistances. The local ground thermal conductivities, preferably evaluated at thermal recovery conditions during DTRTs, were found to vary with depth. Local and effective borehole thermal resistances in most heat exchangers have been calculated, and their differences have been discussed in an effort to suggest better methods for interpretation of data from field tests.

    Large thermal shunt flow between down- and up-going flow channels was identified in all heat exchanger types, particularly at low volumetric flow rates, except in a multi-pipe BHE having an insulated central pipe where the thermal contact between down- and up-coming fluid was almost eliminated.

    At relatively high volumetric flow rates, U-pipe BHEs show a nearly even distribution of the heat transfer between the ground and the secondary fluid along the depth. The same applies to all coaxial BHEs as long as the flow travels downwards through the central pipe. In the opposite flow direction, an uneven power distribution was measured in multi-chamber and multi-pipe BHEs.

    Pipe-in-pipe and multi-pipe coaxial heat exchangers show significantly lower local borehole resistances than U-pipes, ranging in average between 0.015 and 0.040 Km/W. These heat exchangers can significantly decrease the temperature difference between the secondary fluid and the ground and may allow the use of plain water as secondary fluid, an alternative to typical antifreeze aqueous solutions. The latter was demonstrated in a pipe-in-pipe BHE having an effective resistance of about 0.030 Km/W.

    Forced convection in the groundwater achieved by injecting nitrogen bubbles was found to reduce the local thermal resistance in U-pipe BHEs by about 30% during heat injection conditions. The temperatures inside the groundwater are homogenized while injecting the N2, and no radial temperature gradients are then identified. The fluid to groundwater thermal resistance during forced convection was measured to be 0.036 Km/W. This resistance varied between this value and 0.072 Km/W during natural convection conditions in the groundwater, being highest during heat pump operation at temperatures close to the water density maximum.

  • 3.
    Ahmad, Nawaz
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering. KTH Royal Institute of Technology.
    REACTIVE TRANSPORT MODELLING OF DISSOLVED CO2 IN POROUS MEDIA: Injection into and leakage from geological reservoirs2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The geological sequestration of carbon dioxide (CO2) is one of the options of controlling the greenhouse gas emissions. However, leakage of CO2 from the storage reservoir is a risk associated with geological sequestration. Over longer times, large-scale groundwater motion may cause leakage of dissolved CO2 (CO2aq).

    The objectives of this thesis are twofold. First, the modelling study analyzes the leakage of CO2aq along the conducting pathways. Second, a relatively safer mode of geological storage is investigated wherein CO2aq is injected in a carbonate reservoir. A reactive transport model is developed that accounts for the coupled hydrological transport and the geochemical reactions of CO2aq in the porous media. The study provides a quantitative assessment of the impact of advection, dispersion, diffusion, sorption, geochemical reactions, temperature, and heat transport on the fate of leaking CO2aq.

    The mass exchange between the conducting pathway and the rock matrix plays an important role in retention and reactions of leaking CO2aq. A significant retention of leaking CO2aq is caused by its mass stored in aqueous and adsorbed states and its consumption in reactions in the rock matrix along the leakage pathway. Advection causes a significant leakage of CO2aq directly from the reservoir through the matrix in comparison to the diffusion alone in the rock matrix and advection in a highly conducting, but thin fracture. Heat transport by leaking brine also plays an important role in geochemical interactions of leaking CO2aq

    Injection of CO2aq is simulated for a carbonate reservoir. Injected CO2-saturated brine being reactive causes fast dissolution of carbonate minerals in the reservoir and fast conversion of CO2aq through considered geochemical reactions. Various parameters like dispersion, sorption, temperature, and minerals reaction kinetics are found to play important role in the consumption of CO2aq in reactions.

  • 4.
    Ahmad, Nawaz
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering. KTH Royal Institute of Technology.
    Wörman, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering.
    Jarsjö, Jerker
    Stockholm University, Sweden.
    Sanchez-Vila, Xavier
    Universitat Politècnica de Catalunya, UPC-BarcelonaTech, 08034 Barcelona, Spain.
    Bottacin-Busolin, Andrea
    Hellevang, Helge
    Non-isothermal reactive transport modelling of dissolved CO2 leaking through a fractured caprockManuscript (preprint) (Other academic)
    Abstract [en]

    Geological storage of CO2 is considered as one of the mitigation actions for climate change adverse effects. However, some fraction of CO2 dissolved in the brine following injection, may leak from the reservoir through permeable zones such as conducting fractures. In this study we perform the reactive transport modelling of single-phase brine saturated with dissolved CO2 (CO2aq) along a conducting fracture in a clay-rich caprock. This study investigates the role of temperature and various reaction systems on the fate of migrating CO2aq, its geochemical interactions with the carbonate minerals, its conversion in geochemical reactions and associated medium porosity and permeability evolutions along the transport pathway.About 0.64% of leaking CO2aq is found converted into other ions in its geochemical interactions with calcite (simplified geochemical system). Addition of mineral dolomite in the geochemical system (extended geochemical system) results in up to 11% higher mass conversion of CO2 in reactions as compared to the simplified geochemical system. Considering extended geochemical system and heat transport by moving brine resulted in about 27.34% higher mass conversion of CO2 in reactions as compared to the simplified geochemical system. A combination of extended geochemical system, heat transport and sorption resulted in about 82.59% higher mass conversion of CO2 compared to the simplified geochemical system. Leaking CO2aq travelled less than 250 m along the fractured pathway, for a velocity of nearly 19 m/year in the fracture, due to retardation caused by mass stored in aqueous and adsorbed states.

  • 5.
    Ahmad, Nawaz
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering. KTH Royal Institute of Technology.
    Wörman, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering.
    Sanchez-Vila, Xavier
    Universitat Politècnica de Catalunya, UPC-BarcelonaTech, 08034 Barcelona, Spain.
    Bottacin-Busolin, Andrea
    The role of advection and dispersion in the rock matrix on the transport of leaking CO2-saturated brine along a fractured zoneManuscript (preprint) (Other academic)
    Abstract [en]

    CO2 that is injected into a storage reservoir can leak in dissolved form because of brine displacement from the reservoir, which is caused by large-scale groundwater motion. Simulations of the reactive transport of leaking CO2aq along a conducting fracture in a clay-rich caprock are conducted to analyze the effect of various physical and geochemical processes. Whilst several modelling transport studies along rock fractures have considered diffusion as the only transport process in the surrounding rock matrix (diffusive transport), this study analyzes the combined role of advection and dispersion in the rock matrix in addition to diffusion (advection-dominated transport) on the migration of CO2aq along a leakage pathway and its conversion in geochemical reactions. A sensitivity analysis is performed to quantify the effect of fluid velocity and dispersivity. Variations in the porosity and permeability of the medium are observed in response to calcite dissolution and precipitation along the leakage pathway. We observe that advection and dispersion in the rock matrix play a significant role in the overall transport process. For the parameters that were used in this study, advection-dominated transport increased the leakage of CO2aq from the reservoir by nearly 305%, caused faster transport and increased the mass conversion of CO2aq in geochemical reactions along the transport pathway by approximately 12.20% compared to diffusive transport. 

  • 6.
    Ahmad, Nawaz
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering. KTH Royal Institute of Technology.
    Wörman, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering.
    Sanchez-Vila, Xavier
    Bottacin-Busolin, Andrea
    The role of advection and dispersion in the rock matrix on the transport of leaking CO2-saturated brine along a fractured zone2016In: Advances in Water Resources, ISSN 0309-1708, E-ISSN 1872-9657, Vol. 98, 132-146 p.Article in journal (Refereed)
    Abstract [en]

    CO2 that is injected into a geological storage reservoir can leak in dissolved form because of brine displacement from the reservoir, which is caused by large-scale groundwater motion. Simulations of the reactive transport of leaking CO2aq along a conducting fracture in a clay-rich caprock are conducted to analyze the effect of various physical and geochemical processes. Whilst several modeling transport studies along rock fractures have considered diffusion as the only transport process in the surrounding rock matrix (diffusive transport), this study analyzes the combined role of advection and dispersion in the rock matrix in addition to diffusion (advection-dominated transport) on the migration of CO2aq along a leakage pathway and its conversion in geochemical reactions. A sensitivity analysis is performed to quantify the effect of fluid velocity and dispersivity. Variations in the porosity and permeability of the medium are found in response to calcite dissolution and precipitation along the leakage pathway. We observe that advection and dispersion in the rock matrix play a significant role in the overall transport process. For the parameters that were used in this study, advection-dominated transport increased the leakage of CO2aq from the reservoir by nearly 305%, caused faster transport and increased the mass conversion of CO2aq in geochemical reactions along the transport pathway by approximately 12.20% compared to diffusive transport.

  • 7.
    Ahmad, Nawaz
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering. KTH Royal Institute of Technology.
    Wörman, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering.
    Sanchez-Vila, Xavier
    Universitat Politècnica de Catalunya, UPC-BarcelonaTech, 08034 Barcelona, Spain.
    Jarsjö, Jerker
    Stockholm University, Sweden.
    Bottacin-Busolin, Andrea
    Hellevang, Helge
    Injection of CO2-saturated brine in geological reservoir: A way to enhanced storage safetyManuscript (preprint) (Other academic)
    Abstract [en]

    Injection of free phase supercritical CO2 into deep geological reservoirs is associated with risk of considerable return flows towards the land surface due to the buoyancy of CO2, which is lighter than the resident brine in the reservoir. Such upward movements can be avoided if CO2 is injected in the dissolved phase (CO2aq). In this work, injection of CO2-saturated brine in a subsurface carbonate reservoir is modelled. Physical and geochemical interactions of injected low-pH CO2-saturated brine with the carbonate minerals (calcite, dolomite and siderite) are investigated in the reactive transport modelling. CO2-saturated brine, being low in pH, shows high reactivity with the reservoir minerals, resulting in a significant mineral dissolution and CO2 conversion in reactions. Over the injection period of 10 years, up to 16% of the injected CO2 is found consumed in geochemical reactions. Sorption included in the transport analysis resulted in additional quantities of CO2 mass stored. However, for the considered carbonate minerals, the consumption of injected CO2aq is found mainly in the form of ionic trapping.

  • 8.
    Al-Ajmi, Adel
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Wellbore stability analysis based on a new true-triaxial failure criterion2006Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    A main aspect of wellbore stability analysis is the selection of an appropriate rock failure criterion. The most commonly used criterion for brittle failure of rocks is the Mohr-Coulomb criterion. This criterion involves only the maximum and minimum principal stresses, s1 and s3, and therefore assumes that the intermediate stress s2 has no influence on rock strength. When the Mohr-Coulomb criterion had been developed, it was justified by experimental evidence from conventional triaxial tests (s1>s2=s3). Based on triaxial failure mechanics, the Mohr-Coulomb criterion has been extensively used to represent rock failure under the polyaxial stress state (s1>s2>s3).

    In contrast to the predictions of Mohr-Coulomb criterion, much evidence has been accumulating to suggest that s2 does indeed have a strengthening effect. In this research, I have shown that Mohr-Coulomb failure criterion only represents the triaxial stress state (s2=s3 or s2=s1), which is a special case that will only occasionally be encountered in situ. Accordingly, I then developed a new true-triaxial failure criterion called the Mogi-Coulomb criterion. This failure criterion is a linear failure envelope in the Mogi domain (toct-sm,2 space) which can be directly related to the Coulomb strength parameters, cohesion and friction angle. This linear failure criterion has been justified by experimental evidence from triaxial tests as well as polyaxial tests. It is a natural extension of the classical Coulomb criterion into three dimensions.

    As the Mohr-Coulomb criterion only represents rock failure under triaxial stress states, it is expected to be too conservative in predicting wellbore instability. To overcome this problem, I have developed a new 3D analytical model to estimate the mud pressure required to avoid shear failure at the wall of vertical, horizontal and deviated boreholes. This has been achieved by using linear elasticity theory to calculate the stresses, and the fully-polyaxial Mogi-Coulomb criterion to predict failure. The solution is achieved in closed-form for vertical wellbores, for all stress regimes. For deviated or horizontal wellbores, Mathcad programs have been written to evaluate the solution. These solutions have been applied to several field cases available in the literature, and the new model in each case seems to be consistent with the field experience.

  • 9.
    Andersson, J. Christer
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Rock Mass Response to Coupled Mechanical Thermal Loading: Äspö Pillar Stability Experiment, Sweden2007Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    The geological disposal of nuclear waste, in underground openings and the long-term performance of these openings demand a detailed understanding of fundamental rock mechanics. A full scale field experiment: Äspö Pillar Stability Experiment was conducted at a depth of 450 m in sparsely fractured granitic rock to examine the rock mass response between two deposition holes. An oval shaped tunnel was excavated parallel to the σ3 direction to provide access to the experiment and also provide elevated stress magnitudes in the floor. In the tunnel floor two 1.75-m diameter 6-m deep boreholes were excavated so that a 1-m thick pillar was created between them. In one of the holes a confinement pressure of 700 kPa was applied and in the other displacement transducers were installed. The pillar volume was monitored by an Acoustic Emission System. Spatially distributed thermocouples were used to monitor the temperature development as the pillar was heated by electrical heaters. The excavation-induced stress together with the thermal-induced stress was sufficient to cause the wall of the open borehole to yield. The temperature-induced stress was increased slowly to enable detailed studies of the rock mass yielding process. Once the rock mass loading response was observed, the rock mass was unloaded using a de-stress slotting technique.

    This thesis focuses on the in-situ study of the rock mass response to coupled mechanical thermal loading and thermal-mechanical unloading. The experiment, its design, monitoring and observations are thoroughly described. An estimate of the yielding strength of the rock mass is presented and compared with laboratory test and results from other rock mass conditions reported elsewhere in the open literature. General conclusions about the effect of the confining pressure and the observations from the unloading of the pillar are also presented.

    Important findings are that the yielding strength of the rock mass has been successfully determined, low confinement pressures significantly affects the onset of yielding, the primary mode of fracture initiation and propagation is extensional, no significant time dependency of the yielding process was observed. The unloading studies also indicated that what appeared to be shear bands likely was a propagating zone of extensile failure that weakened the rock so that displacements in the shear direction could occur.

  • 10.
    Ask, Daniel
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    New developments in the Integrated Stress Determination Method and their application to rock stress data at the Aspo HRL, Sweden2006In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, Vol. 43, no 1, 107-126 p.Article in journal (Refereed)
    Abstract [en]

    The Integrated Stress Determination Method (ISDM) is a powerful tool for estimating the regional stress tensor from in-situ measurements of local stress tensors using a wide variety of stress measuring techniques. This study presents new developments of the ISDM: The stress field may be described with up to 12 model parameters; and is applicable to data from CSIR- and CSIRO HI-type of overcoring devices, hydraulic fracturing, hydraulic tests of pre-existing fractures (HTPF), as well as to combined data sets. Furthermore, in combined data sets, the hydraulic fracturing and/or HTPF data may be used to constrain the average elastic parameters, Young's modulus and Poisson's ratio. The new ISDM developments were applied to the extensive and recently re-analysed rock stress data at the Aspo Hard Rock Laboratory. The results reveal a good fit of the re-analysed data. Overall, the re-analysis indicates that the stress field at Aspo HRL is relatively well constrained and consistent with depth. The NE-2 Fracture Zone influences the stresses, and dividing the regional stress field into a NW and a SE stress domain. When the hydraulic fracturing data were used to constrain the average elastic parameters, Young's modulus, E, and Poisson's ratio, v, quite similar results were obtained (E = 50.8 GPa and v = 0.33) compared with results from biaxial tests of overcore samples (E = 61.6 MPa and v = 0.26).

  • 11.
    Asp, Kenneth
    Swedish National Road and Transport Research Institute.
    VTI:s och KFB:s forskardagar: del 2. Rapportsammanställning av föredrag vid forskardagarna i Linköping 2000-01-12-13 beträffande: EU-projektet ALT-MAT, redovisning av resultat - trafik och miljöprojekt KFB - bilismen i ett kulturellt perspektiv - tema nedbrytning av väg - tema upphandling - tema vägyta-trafikeffekter - tema infrastrukturens sårbarhet - jämförelse mellan olika lösningar - hälsoeffekter och attityder - olika åtgärder i vägtrafiken-möjligheter och effekter - väginformatik-nya perspektiv och aktuella insatser2000Conference proceedings (editor) (Other academic)
  • 12.
    Belonoshko, Anatoly B.
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Lukinov, Timofiy
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Rosengren, Anders
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory. KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. AlbaNova University Center, Sweden.
    Bryk, Taras
    Litasov, Konstantin D.
    Synthesis of heavy hydrocarbons at the core-mantle boundary2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, 18382Article in journal (Refereed)
    Abstract [en]

    The synthesis of complex organic molecules with C-C bonds is possible under conditions of reduced activity of oxygen. We have found performing ab initio molecular dynamics simulations of the C-O-H- Fe system that such conditions exist at the core-mantle boundary (CMB). H2O and CO2 delivered to the CMB by subducting slabs provide a source for hydrogen and carbon. The mixture of H2O and CO2 subjected to high pressure (130 GPa) and temperature (4000 to 4500 K) does not lead to synthesis of complex hydrocarbons. However, when Fe is added to the system, C-C bonds emerge. It means that oil might be a more abundant mineral than previously thought.

  • 13.
    Benavente, Martha
    et al.
    Faculty of Chemical Engineering, National University of Engineering (UNI), Managua, Nicaragua.
    Casas, Jesús M.
    Dept of Chemical Engineering, University of Chile (UChile), Santiago, Chile.
    Martínez, Joaquín
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Speciation of Cyanide and Compounds related to the Washing of Gold Ore Tailing2002In: CIQ 2002: Proceedings of the 15th Chilean Congress of Chemical Engineering, Punta Arenas, Chile, 2002Conference paper (Refereed)
  • 14.
    Bergkvist, Adam
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Mobil bergkrossning: Energibehov och emissioner2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I detta examensarbete undersöks energibehov och emissioner hos mobila krossanläggningar tillhörande NCC Industry AB. Bergtäkterna Eker och Dylta i Örebro län samt Mörtsjön i Södermanlands län har studerats och analyserats. Dessa bergtäkter producerar ballastprodukter som till större del används i anläggningsindustrin och vid asfaltstillverkning. Tester har genomförts på den elektriska konsumtionen i de olika anläggningarna för att beräkna relevanta parametrar som varit eftersökta. Produktionsrapporter och elmätningar har sammanställts, löpande under ett flertal veckor, i ett räknedokument för att kunna erhålla efterfrågade datavärden.

    De sökta faktorerna har varit energibehov i form av kWh/Ton samt emissioner i form av kg CO2/Ton. Mätningarna avser krossar, siktar och transportband vid maskinuppställningar för mobil krossning. Resultaten visar att värden på elförbrukningen uppgår till 2,1 kWh/ton med en variation från 1,1 till 3,1 kWh/ton beroende på ingående maskiner och driftförhållanden. För CO2-emissionerna var motsvarande genomsnitt 0,9 kg CO2/ton vid dieseldrift med variation 0,4 till 1,6 kg CO2/ton. Vid omräkning till en tänkt nätdrift med el låg genomsnittet på 0,17 kg CO2/ton. Beräkningarna skall bidra till en grönare tillverkningsprocess av ballastprodukter och kom att visa att skillnaderna i utsläpp (kg CO2/Ton) är uppemot 90 % större vid dieseldrift gentemot eldrift på en av de olika anläggningarna. Dessa resultat har sedan analyserats och rekommendationer görs för framtida drift och investeringar i samtliga anläggningar. Dessa rekommendationer utvärderas sedan av NCC för att avgöra huruvida de är relevanta eller icke. Att genomföra ombyggnationer och modifiera utrustningen kan dock vara mycket kostsamt. Elektricitetsproduktionen är inte analyserad i rapporten. Beräkningar är utförda med förutsättningen att elen är av nordisk mix. Dessa uppgifter är inhämtade från Naturvårdsverket. En ekonomisk analys av denna investering ingår inte i denna rapport. 

  • 15. Berumen, S. A.
    et al.
    Pérez-Megino, L. P.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Socioeconomic ranking for the development of coal-mining regions in Europe2016In: Revista de Métodos Cuantitativos para la Economía y la Empresa, ISSN 1886-516X, Vol. 21, no 1, 39-57 p.Article in journal (Refereed)
    Abstract [en]

    The socioeconomic situation of European coalfields is highly heterogeneous. On the one hand, successful examples comprise regions that long ago embraced internationalization, innovation and/or restructuring strategies. In those regions where the aforementioned strategies were fruitful, the development of new production methods led to gradual repopulation. Less successful examples, however, are likely to experience undesired effects as a consequence of both the suppression of aid (EU- and regional- level) and the liberalization of EU mining markets, starting on December 31, 2018. This papers aims to provide a method to accurately assess the socioeconomic situation of these regions. As such a method is rooted in previous policies, it enables the identification of welfare-enhancing policies for the inhabitants of European coalfield regions.

  • 16.
    Casas, Jesús M.
    et al.
    Dept of Chemical Engineering, University of Chile (UChile), Santiago, Chile.
    Martínez, Joaquín
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Speciation of Copper Mine Solutions1994In: CONAMET'94 & ALAMET III, Vol. 1: Proceedings of the 8th Chilean Congress of Metallurgy and the 3rd Congress of the Latin-American Association of Metallurgy and Materials, Antofagasta, Chile: Catholic University of North , 1994, 1-10 p.Conference paper (Refereed)
  • 17.
    Casas, Jesús M.
    et al.
    Dept of Chemical Engineering, University of Chile (UChile), Santiago, Chile.
    Martínez, Joaquín
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Vargas, T.
    Dept of Chemical Engineering, University of Chile (UChile), Santiago, Chile.
    Two-Dimensional Model of Heat and Gas Transport and Mineral Oxidation in Copper Bioleaching Dump1995In: Biohydrometallurgical Processing, Vol. 1: Proceedings of the International Biohydrometallurgy Symposium (IBS-95) / [ed] Vargas, T., Jerez, C.A., Wiertz, J.V., Toledo, H., Santiago, Chile: University of Chile , 1995, 447-457 p.Conference paper (Refereed)
  • 18.
    Casas, Jesús M.
    et al.
    Dept of Chemical Engineering, University of Chile (UChile), Santiago, Chile.
    Martínez, Joaquín
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Vargas, T.
    Dept of Chemical Engineering, University of Chile (UChile), Santiago, Chile.
    Influence of Bacterial Activity on Temperature, Oxygen Profiles and Leaching Rates in the Bioleaching of Copper Sulfide Ore Beds1997In: IBS 97: Proceedings of the International Biohydrometallurgy Symposium, Sydney, Australia: Australian Mineral Foundation , 1997, M5-3.1 p.Conference paper (Refereed)
  • 19.
    Casas, Jesús M.
    et al.
    Dept of Mining Engineering, University of Chile, Santiago, Chile.
    Vargas, T.
    Dept of Chemical Engineering, University of Chile, Santiago, Chile.
    Martínez, Joaquín
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Bioleaching model of a copper-sulfide ore bed in heap and dump configurations1998In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 29, no 4, 899-909 p.Article in journal (Refereed)
    Abstract [en]

    A two-dimensional (2-D) model for a heap or dump bioleaching of a copper ore containing mainly chalcocite and pyrite has been developed. The rate of the mineral sulfide dissolution was related to the rate of oxidation by bacteria attached onto the ore surface. The latter was calculated using the model of Michaelis-Menten, where both temperature and dissolved oxygen in the leach solution were taken into account by the kinetic equation. Oxygen transport through the ore bed was associated with natural air convection originating from the decrease in gas density inside the ore bed, which was attributable not only to heating, but also to humidification and decrease in the oxygen concentration. The model was used to estimate air-velocity fields and profiles of temperature and oxygen concentrations as well as mineral conversions during the bioleaching operation for ore beds with different pyrite contents, bacterial populations, widths, heights, and permeabilities. The model provides a useful tool for the design, improvement, and optimization of industrial operating conditions.

  • 20.
    Casas, Jesús M.
    et al.
    Dept of Chemical Engineering, University of Chile (UChile), Santiago, Chile.
    Vargas, T.
    Dept of Chemical Engineering, University of Chile (UChile), Santiago, Chile.
    Martínez, Joaquín
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Modelling of Bioleaching from Low Grade Copper Sulphide Ore1993In: Biohydrometallurgical Technologies, Vol. 1: Proceedings of an International Biohydrometallurgy Symposium (IBS'93) / [ed] A.E. Torma, J.E. Wey, V.I. Lakshmanan, The Minerals, Metals & Materials Society , 1993, 249-258 p.Conference paper (Refereed)
  • 21. Chen, Yifeng
    et al.
    Hu, Shaohua
    Wei, Kai
    Hu, Ran
    Zhou, Chuangbing
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Experimental characterization and micromechanical modeling of damage-induced permeability variation in Beishan granite2014In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 71, 64-76 p.Article in journal (Refereed)
    Abstract [en]

    Triaxial compression tests with measurements of permeability were performed on core granite samples taken at 450-550 m depth from the Beishan area in Gansu Province, a potential site for China's high-level radioactive waste (HLW) disposal. Corresponding to the distinct features in the stress-strain behaviors, the permeability of the Beishan granite was found to evolve with a clear permeability decrease in the initial microcrack closure region, a constant permeability value in the elastic region and a dramatic permeability increase in the crack growth region. The permeability increases by up to and over two orders of magnitude as deviatoric stress increases up to sample failure; but at a given deviatoric stress, the permeability reduces remarkably with the increase of confining pressure. An empirical upper bound permeability model was presented by relating the mechanisms involved in the microstructure alteration to the permeability change, and the experimental results were well simulated by the proposed model. Combined with field geological characterization and numerical simulation, the implications of the experimental results for China's HLW disposal were discussed.

  • 22.
    Dong, Zheng
    University of Gävle, Department of Technology and Built Environment.
    Automated Extraction and Retrieval of Metadata by Data Mining: a Case Study of Mining Engine for National Land Survey Sweden2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Metadata is the important information describing geographical data resources and their key elements. It is used to guarantee the availability and accessibility of the data. ISO 19115 is a metadata standard for geographical information, making the geographical metadata shareable, retrievable, and understandable at the global level. In order to cope with the massive, high-dimensional and high-diversity nature of geographical data, data mining is an applicable method to discover the metadata.

    This thesis develops and evaluates an automated mining method for extracting metadata from the data environment on the Local Area Network at the National Land Survey of Sweden (NLS). These metadata are prepared and provided across Europe according to the metadata implementing rules for the Infrastructure for Spatial Information in Europe (INSPIRE). The metadata elements are defined according to the numerical formats of four different data entities: document data, time-series data, webpage data, and spatial data. For evaluating the method for further improvement, a few attributes and corresponding metadata of geographical data files are extracted automatically as metadata record in testing, and arranged in database. Based on the extracted metadata schema, a retrieving functionality is used to find the file containing the keyword of metadata user input. In general, the average success rate of metadata extraction and retrieval is 90.0%.

    The mining engine is developed in C# programming language on top of the database using SQL Server 2005. Lucene.net is also integrated with Visual Studio 2005 to build an indexing framework for extracting and accessing metadata in database.

  • 23. Englund, David
    et al.
    Brunberg, Anna
    Jacks, Gunnar
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    A CASE STUDY OF A FRESHWATER PEARL MUSSEL (MARGARITIFERA MARGARITIFERA) POPULATION IN CENTRAL SWEDEN2008In: Geografiska Annaler, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 90A, no 4, 251-258 p.Article in journal (Refereed)
    Abstract [en]

    Most of the Margaritifera margaritifera populations in Sweden are not reproducing. Land use such as forestry, eutrophication and water regulation for hydropower are commonly reported causes for the absence of reproduction. A brook with a very dense population of pearl mussels has been investigated with regard to the age distribution of the population and their habitat, in order to discover the reason for the absence of reproduction. The population consisted almost entirely of old mussels with very few young ones. The water flow and chemistry of the water are very stable and well buffered, due to a large glacifluvial deposit in the catchment area. The substrate in the stream is favourable and well aerated to a depth of at least 15 cm. Forestry has been practised with care for at least the last 15 years to avoid siltation of the stream sediments. The most likely reason for the lack of reproduction seems to be the water regulation of the main stream introduced 60 years ago, which has left the main stream dry seasonally. This is likely to have affected the population of brown trout which is the host for the first life-stage of the mussels, the glochidia.

  • 24.
    Fidalgo, Alexandre Barreiro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Can H-2 enhance the oxidative dissolution of UO2?2016In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 477, 85-87 p.Article in journal (Refereed)
  • 25.
    Ghodrati, Behzad
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kumar, UdayLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.Schunnesson, HåkanLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Proceeding of the 26th International Symposium on Mine Planning and Equipment Selection: MPES 20172017Conference proceedings (editor) (Refereed)
  • 26.
    Ghosh, Rajib
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Schunnesson, Håkan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Gustafson, Anna
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Monitoring of Drill System Behavior for Water-Powered in-the-hole (ITH) drilling2017In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 7, no 7, 121Article in journal (Refereed)
    Abstract [en]

    A detailed understanding of the drilling system and the drilling control is required to correctly interpret rock mass conditions based on monitored drilling data. This paper analyses data from hydraulic in-the-hole (ITH) drills used in LKAB’s Malmberget mine in Sweden. Drill parameters, including penetration rate, percussive pressure, feed pressure, and rotation pressure, are monitored in underground production holes. Calculated parameters, penetration rate variability, rotation pressure variability, and fracturing are included in the analysis to improve the opportunity to predict rock mass conditions. Principal component analysis (PCA) is used to address non-linearity and variable interactions. The results show that the data contain pronounced hole length-dependent trends, both linear and step-wise linear, for most parameters. It is also suggested that monitoring can be an efficient way to optimize target values for drill parameters, as demonstrated for feed force. Finally, principal component analysis can be used to transfer a number of drill parameters into single components with a more straightforward geomechanical meaning

  • 27.
    Gustavsson, Daniel
    et al.
    Linköping University, Department of Management and Engineering.
    Wallin, Jakob
    Linköping University, Department of Management and Engineering.
    Simulering av hydrauliska dämpare i borrslagverk2008Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    This master thesis consists of the creation of shock absorber models for percussive rock drills. A model of the rock was also developed. These models were connected to existing models of the rock drill to create a complete simulation of the rock drilling process.

    When the models had been created the rock model was evaluated by comparison with measured values from lab tests. The verified rock model was then used to evaluate the shock absorber models.

    Four new shock absorber concepts have been developed. Three of these have been modelled, while the fourth have only been sketched and described.

    The evaluation of the models showed the following:

    • Simulations of the single shock absorber don’t correlate to reality very well. The movement is too rapid and poorly damped.

    • The simulated behaviour of the tandem shock absorber corresponds to reality, but the simulated hydraulic pressures aren’t reliable and neither is the damping.

    • Simulation of the double shock absorber reflects reality fairly well, although the model of the check valve can be improved.

    • There are problems with fluttering damper pressures in simulation whenever an accumulator is connected directly to the damper volume. The problem doesn’t exist if there is a line or an orifice with enough losses between the volume and the accumulator.

    • The feeder system needs to be modelled.

  • 28.
    Haglund, Elin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Fukthaltens påverkan på maskintillverkad betongsand vid Vikan Kross2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis examines how the moisture content of the input material as well as the speed setting on the VSI-crusher affect grain shape and filler content in manufactured concrete sand. The aim of this thesis is to determine the most effective speed setting on the VSI-crusher and additionally to examine the capacity of the windsift at different moisture levels. Some suitable instruments for measuring humidity and determining grain shapes have also been studied.

    Sampling was conducted in the concrete sand plant at Vikan Kross owned and operated by Skanska Asfalt and Betong AB. Tests to produce grain size distribution curve, fleakiness index and moisture content were performed at Skanska´s laboratory in Angered.

    The impact of moisture is more evident at a lower speed setting on the VSI-crusher, the filler content is more than doubled when the material goes from dry to humid.

    The grain shape is improved at a higher speed setting on the VSI-crusher, also the filler content in the manufactured concrete sand is lower. Best grain shape is achieved in dry material.

    The amount of filler that the crusher generates is also lower at the higher speed setting, except for very wet material. The windsifts ability to reduce filler content in the material varies greatly between moisture levels.

    The study of instruments resulted in three instruments considered suitable for concrete sand manufacturing, one portable and one permanently installed from Franz Ludwig GmbH for moisture measurement and one instrument from Retsch Technology for determination of grain shape.

  • 29.
    Hellman, Fredrik
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Åkesson, Urban
    Trafikverket.
    Eliasson, Thomas
    SGU.
    Kvantitativ petrografisk analys av bergmaterial: en metodbeskrivning2011Report (Other academic)
    Abstract [en]

    The main mineralogical properties of rock materials used in road construction are described from a technical perspective in this VTI report. It is the quality of the rock material in combination with pavement design that determines future maintenance needs and technical lifetime of road construction. The report also presents a microscopic method for the determination of rock quality.

    Road structures are composed of aggregates of different size fractions. Unbound aggregates are used for sub-base and base course layers. These layers should act as a foundation to be able to handle traffic loads and climate variations without deformation and break down. The properties of the unbound layers are largely determined by the rock quality (mineralogy, e.g.), grading curve and particle shape. Inferior materials can be used in less sensitive parts of the structure, while materials with high quality should be used in the more sensitive upper parts of the structure. In this way one can use the resources of rock quarries in the best way. The quality of the rock material and manufacturing determines future maintenance needs and technical lifetime of road construction.

    The report contains a brief literature review in which the main mineralogical properties of the rock are described from a technical perspective.

    The report presents a microscopic method for the determination of rock quality. It is designed to assess the technical characteristics of the rock for use as unbound material in road constructions. The method can be used in other contexts where technical characterizations of rock material are important. The method presents the quantitative assessment of mineralogy, grain boundaries, grain size, foliation and micro cracks. Appendixes contain examples of a completed analysis and pictures to facilitate the assessment and quantification of thin sections under microscope.

  • 30.
    Herbert, Roger
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Björnström, Joakim
    Barrier system for the treatment of nitrogen effluents from the Malmberget iron mine2009In: Proceedings, Securing the Future. Skellefteå, Sweden, 2009Conference paper (Refereed)
    Abstract [en]

    At the Malmberget iron mine in northern Sweden, nitrogen from undetonated explosives is discharged from the mine with process water. After passing through a settling pond, excess process water is discharged to the Linaälv River via a spillway. Because of the risk for eutrophication in rivers and coastal areas downstream, it is necessary to decrease the N levels in the effluent waters. This study presents the results from laboratory column experiments under water – saturated conditions, conducted at room temperature and 5oC, which will be used in the design of a pilot-scale barrier system. The columns were filled with a reactive substrate consisting of sawdust and activated sewage sludge. The results of the room temperature experiments demonstrated that nitrate removal efficiency was >95% for flow rates < 341 liters d-1 m-3 reactive mixture. However, at flow rates of ~700 liters d-1 m-3 reactive mixture, nitrate removal efficiency decreased to ~64%. Tracer experiments indicated an increasing degree of channeling in the columns as flow rate increased, thus leading to a reduction in removal efficiency. Apparent denitrification rates were estimated to 2.8 -9.3 g N d-1 m-3 and 2.2 g N d-1 m-3 at room temperature and 5oC, respectively.

  • 31.
    Herbert, Roger
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Höckert, Linda
    Mine waste stabilization with biosludge and paper mill waste2009In: Proceedings, Securing the Future. Skellefteå, 2009Conference paper (Refereed)
    Abstract [en]

     

  • 32.
    Hudson, John A.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Stephansson, Ove
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Andersson, J
    Guidance on numerical modelling of thermo-hydro-mechanical coupled processes for performance assessment of radioactive waste repositories2005In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, Vol. 42, no 5-6, 850-870 p.Article in journal (Refereed)
    Abstract [en]

    This paper provides advice on how to incorporate thermo-hydro-mechanical (THM) coupled processes into performance and safety assessments and design studies for radioactive waste disposal in geological formations. The advice is based on work conducted for the EU research project BENCHPAR: "Benchmark Tests and Guidance on Coupled Processes for Performance Assessment of Nuclear Waste Repositories". In Section 1, there is an explanation of why numerical analyses incorporating THM mechanisms are required for radioactive waste studies and background material on the subject is provided. Then, the THM processes and their interactions are explained in Section 2. Three case examples of THM numerical analysis are presented in Section 3 to illustrate the type of work that can be conducted to study the near-field, upscaling, and the far-field. The importance and priority of the THM couplings are summarized in Section 4. Recommended soft and hard auditing procedures are presented in Section 5. We place special emphasis on the fact that the most important step in numerical modelling is not executing the calculations per se, but the earlier conceptualization of the problem regarding the dominant processes, the material properties and parameters, the engineering perturbations, and their mathematical presentations. The associated modelling component of addressing the uncertainties and estimating their influence on the results is also important. Thus, the specific models and codes should be studied first to evaluate the harmony between the nature of the problem and the nature of the codes. The tactical use of particular numerical techniques will then be based on a sound strategic foundation. An associated listing of bullet point recommendations and issues for future directions for this THM subject area is given in Section 6.

  • 33.
    Hugoson, Alexander
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Précenth, Henrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Kvalitetssäkrad Bultplansgenerering2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis in rock mechanics was carried out on behalf of Boliden during the period of April to May 2016 at Boliden underground mine in Garpenberg.

    The bolting rigs in Garpenberg are equipped with a new system to assist the operator to position the rock bolts according to the planned bolting pattern. This means that the planned bolt spacing is manually inserted in the bolt positioning software and by referring to two previously installed bolts the planned location of the next bolting fan is generated and shown in the software.

    The aim of the thesis was to perform a quality control regarding the bolting rigs navigation system by reference bolting. Through comparing the bolting rigs data log with the measurements of the actual outcome it was determined if the location of the bolts were positioned according to the specified rock support plan.

    The work was performed by measuring the location of eight bolting fans (a total of 104 installed bolts) with a total station. The data was then compared with a data log that is automatically generated in the software at the installation of each bolt. The data has mainly been analysed using computer software such as AutoCAD and Microsoft Excel in order to calculate deviation of the bolting rigs data log and the measurements of actual outcome (mean values, standard deviation and normal distribution).

    The result of the measurements shows that 30.4% of all rock bolts are in the range of 0-3 centimetres from their planned locations.

    The analysis shows a total standard deviation of 0.103 metres.

    The analysis of deviations requires that the sensors on the joints of the bolting rigs are calibrated for the bolt positioning software and therefore control measurements were carried out.

  • 34.
    Höckert, Linda
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Kemisk stabilisering av gruvavfall från Ljusnarsbergsfältet med mesakalk och avloppsslam2007Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Mine waste from Ljusnarsbergsfältet in Kopparberg, Sweden, is considered to constitute a great risk for human health and the surrounding environment. Some of the waste rock consists of sulphide minerals. When sulphide minerals come into contact with dissolved oxygen and precipitation, oxidation may occur resulting in acid mine drainage (AMD) and the release of heavy metals. The purpose of this study has been to characterise the waste material and try to chemically stabilize the waste rock with a mixture of sewage sludge and calcium carbonate. The drawback of using organic matter is the risk that dissolved organic matter can act as a complexing agent for heavy metals and in this way increase their mobility. An additional study to examine this risk has therefore also been performed.

    The project started with a pilot study in order to identify the material fraction that was suitable for the experiment. When suitable material had been chosen, a column test was carried out for the purpose of studying the slurry’s influence on the mobility of metals along with the production of acidity. To clarify the organic material’s potential for complexation a pH-stat batch test was used. Drainage water samples, from the columns, were regularly taken during the experiment. These samples were analysed for pH, electrical conductivity, alkalinity, redox potential, dissolved organic carbon (DOC), sulphate and leaching metals. The effluent from the pH-stat-test were only analysed on a few occasions and only for metal content and change in DOC concentration.

    The results from the laboratory experiments showed that the waste rock from Ljusnarsberg easily leached large amounts of metals. The stabilization of the waste rock succeeded in maintaining a near neutral pH in the rock waste leachate, compared to a pH 3 leachate from untreated rock waste The average concentration of copper and zinc in the leachate from untreated waste rock exceeded 100 and 1000 mg/l respectively, while these metals were detected at concentrations around 0.1 and 1 mg/l, respectively, in the leachate from the treated wastes. Examined metals had concentrations between 40 to 4000 times lower in the leachate from treated waste rock, which implies that the stabilisation with reactive amendments succeeded. The long term effects are, however, not determined. The added sludge contributed to immobilise metals at neutral pH despite a small increase in DOC concentration. The problem with adding sludge is that if pH decreases with time there is a risk of increased metal leaching.

  • 35.
    Höckert, Linda
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences.
    Kemisk stabilisering av gruvavfall från Ljusnarsbergsfältet med mesakalk och avloppsslam: Chemical stabilization of mine waste with sewage sludge and calcium carbonate residues2007Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Chemical stabilization of mine waste from Ljusnarsbergsfältet with sewage sludge and calcium carbonate residues

    Mine waste from Ljusnarsbergsfältet in Kopparberg, Sweden, is considered to constitute a great risk for human health and the surrounding environment. Some of the waste rock consists of sulphide minerals. When sulphide minerals come into contact with dissolved

    oxygen and precipitation, oxidation may occur resulting in acid mine drainage (AMD) and the release of heavy metals. The purpose of this study has been to characterise the waste material and try to chemically stabilize the waste rock with a mixture of sewage sludge and calcium carbonate. The drawback of using organic matter is the risk that dissolved organic matter can act as complexing agents for heavy metals and in this way increase their mobility. An additional study to examine this risk has therefore also been performed.

    The project started with a pilot study in order to identify the material fraction that was suitable for the experiment. When suitable material had been chosen, a column test was carried out for the purpose of studying the slurry’s influence on the mobility of metals along with the production of acidity. To clarify the organic material’s potential for

    complexation a pH-stat batch test was used. Drainage water samples, from the columns,

    were regularly taken during the experiment. These samples were analyzed for pH, electrical conductivity, alkalinity, redox potential, dissolved organic carbon (DOC), sulphate and leaching metals. The effluent from the pH-stat-test was only analyzed on a few occasions and only for metal content and change in DOC concentration.

    The results from the laboratory experiments showed that the waste rock from Ljusnarsberg easily leached large amounts of metals. The stabilization of the waste rock succeeded in maintaining a near neutral pH in the rock waste leachate, compared to a pH 3 leachate from untreated rock waste The average concentration of copper and zinc in the leachate from untreated waste rock exceeded 100 and 1000 mg/l respectively, while these metals were detected at concentrations around 0.1 and 1 mg/l, respectively, in the leachate from the treated wastes. Examined metals had concentrations between 40 to 4000 times lower in the leachate from treated waste rock, which implies that the stabilization with reactive amendments succeeded. The long term effects are, however, not determined. The added sludge contributed to immobilize metals at neutral pH despite a small increase in DOC concentration. The problem with adding sludge is that if pH decreases with time there is a risk of increased metal leaching.

  • 36.
    Isaksson, Nils
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Lundström, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Dammsäkerhetsutvärdering samt utformning av dammregister och felrapporteringssystem för svenska gruvdammar2005Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A lot of mine waste rock and tailings arise from all mining processes and have to be stored in an appropriate way. Tailings are deposited in impoundments retained by tailings dams. The objective of tailings dams is to retain the slurry from the mining process and in that way prevent spill into the surroundings that might be harmful for the environment. Tailings dams are often constructed as staged embankments so that construction costs and demand of materials are spread more evenly over the period of deposition.

    The objective of this thesis has been to compile information about and evaluate events at Swedish tailings dams and also to develop a collective database for all Swedish mining companies for all tailings dams and all events that occur at tailings dams.

    Information about 60 events at Swedish tailings dams has been gathered and evaluated. The evaluation has been performed by comparison between and analysis of individual parameters and also by use of a multivariate statistical method called PLS. The statistical analysis shows a decrease in the numbers of events during the last five years, which indicates improved dam safety within the mining industry. The analysis also shows that severe events and the human factor might be related when it comes to the initiating cause of the event. Further relations between the parameters and the severity of the events can be seen from the PLS-analysis, for example that low and short tailings dams to a greater extent are subjected to severe events. To be able to draw more reliable conclusions further studies with a more complete basic data are needed.

    This work has shown a need of a collective database within the Swedish mining industry for tailings dams and occurring events at tailings dams so that more complete basic data could be obtained for future studies. A structure for such a database has been developed in Microsoft Access 2000. The aim of the database is to facilitate feedback within the mining industry and to gather comprehensive data for future statistical evaluations.

  • 37.
    Jianliang, Wang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Global Energy Systems. China University of Petroleum - Beijing.
    Davidsson, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Global Energy Systems.
    Höök, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Global Energy Systems.
    Lianyong, Feng
    Chinese coal supply and future production outlooks2013In: Energy, ISSN 0360-5442, Vol. 60, 204-214 p.Article in journal (Refereed)
    Abstract [en]

    China's energy supply is dominated by coal, making projections of future coal production in China important. Recent forecasts suggest that Chinese coal production may reach a peak in 2010–2039 but with widely differing peak production levels. The estimated URR (ultimately recoverable resources) influence these projections significantly, however, widely different URR-values were used due to poor understanding of the various Chinese coal classification schemes. To mitigate these shortcomings, a comprehensive investigation of this system and an analysis of the historical evaluation of resources and reporting issues are performed. A more plausible URR is derived, which indicates that many analysts underestimate volumes available for exploitation. Projections based on the updated URR using a modified curve-fitting model indicate that Chinese coal production could peak as early as 2024 at a maximum annual production of 4.1 Gt. By considering other potential constraints, it can be concluded that peak coal in China appears inevitable and immediate. This event can be expected to have significant impact on the Chinese economy, energy strategies and GHG (greenhouse gas) emissions reduction strategies.

  • 38.
    Jing, Lanru
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Hudson, J. A.
    Fundamentals of the hydro-mechanical behaviour of rock fractures: roughness characterization and experimental aspects2004In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, Vol. 41, no 3, 383-383 p.Article in journal (Refereed)
    Abstract [en]

    The coupled hydro-mechanical behaviour of rock fractures plays an important role in design, performance and safety assessments of rock engineering projects. However, due to the complexity in the mathematical representation of the fracture surface geometry and its effects on the stress-flow behaviour of the fractures, and the limitations in the test conditions in laboratories, significant lack of knowledge still exists in testing and modelling approaches regarding rock fractures. Based on a general review of the roughness characterization and shear-flow testing of rock fractures, this paper presents the definition of the stationarity threshold of roughness, and a combined experimental-numerical approach for simulating rock fracture testing conditions for more general fluid flow behaviour of the rock fractures. The conclusions are that fracture roughness characterization must be conducted and represented in three-dimensions and the more general fluid flow behaviour cannot be observed with conventional parallel shear-flow tests or compressionradial flow tests. Numerical simulations are needed to reveal more general behaviour of stress-flow processes of rock fractures with boundary and loading conditions that are difficult or impractical in laboratory tests.

  • 39.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Influence of scale and matedness on the peak shear strength of fresh, unweathered rock joints2016In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 82, 36-47 p.Article in journal (Refereed)
    Abstract [en]

    It is widely recognized that the mechanical parameters for unfilled and rough rock joints, such as the peak shear strength, can vary with scale. However, due to contradictory results concerning the extent and nature of the scale effect reported in the literature, it is still a debated subject. A conceptual model developed by Johansson and Stille 2014 suggests how roughness and matedness at different scales influences the peak shear strength for fresh, rough and unweathered joint. However, the model's ability to predict how the roughness and matedness affects the peak shear strength at different scales was not verified. The aim of this paper is to investigate the ability of the conceptual model to estimate the peak shear strength at different degrees of matedness and scales. A series of direct shear test were carried out at two different scales and two different degrees of matedness. The peak shear strength from the tests was compared to the peak shear strength calculated with the conceptual model. The results showed that the model can predict the peak shear strength for both the perfectly mated and the unmated joints. No scale effect was observed in the shear tests, which is in line with the predictions using the model. The influence of matedness in combination with scale might explain some of the contradictory findings regarding the scale effect.

  • 40.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Shear Strength of Unfilled and Rough Rock Joints in Sliding Stability Analyses of Concrete Dams2009Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The horizontal water load combined with uplift forces implies that concrete damsare sensitive for sliding. At the same time, the safety of concrete dams againstsliding in the rock foundation is associated with large uncertainties. One of themain uncertainties regards the shear strength of rock joints.

    Several failure criteria exist to express the shear strength for unfilled and roughrock joints. However, these criteria do not in general consider a possible scaleeffect which means that the shear strength could be lower at larger scales. Somesuggestions exist for how a possible scale effect could be considered, but theseare mainly based on empiric grounds. This means that there exists a need of amore detailed and conceptual understanding on the scale effect of rock joints.

    In an attempt to increase the understanding on the scale effect of unfilled andrough rock joints, a conceptual model was derived. The model is based on theassumptions that contact points occur at the steepest asperities facing the sheardirection and that their total area could be expressed with adhesion theory. Fractaltheory is used in order to idealize the surface roughness by superposition ofasperities at different scales. Based on changes in the size and number of contactpoints, the conceptual model suggests that the scale effect does not occur for alltypes of rock joints. Perfectly mated joints are suggested to not exhibit any scaleeffect while a considerable scale effect could be expected for unmated joints.

    The practical implications from this, for foundations with unfilled joints, is thatunmated joints with large aperture are most critical for the sliding stability ofconcrete dams, since these joints probably are the ones with longest persistenceand lowest shear strength.

    In order to study the scale effect of rock joints further, eighteen shear tests atdifferent scales were performed. All of the samples were taken from the rockfoundation at Långbjörn hydropower station. Possible scale effects could beobserved, but no firm conclusions could be made, mainly due to different surfacecharacteristics of the tested joints. Three of the samples were also used toinvestigate the accuracy of the conceptual model. This investigation revealed thatit may be necessary to distinguish between weathered and unweathered joints,since the distribution of contact points appears to become more randomlydistributed for a weathered joint which in turn results in lower friction angles.

    In Sweden, dam safety is governed by the Swedish power company’s guidelinesfor dam safety, RIDAS. When the Swedish guidelines were compared withguidelines and regulations in other countries, it was realized that there exists aneed for a more balanced evaluation of the sliding stability for concrete damsfounded on rock in Sweden. In a first step of development, it can be based onsafety factors and an increased use of investigations. However, in a second step, anatural way of the development of RIDAS would be in a direction towardsreliability based methods.

  • 41.
    Johansson, Fredrik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Bagheri, Mehdi
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Stille, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Variation of mechanical parameters of a slightly weathered joint in granite estimated from fourteen shear tests2010In: ROCK MECHANICS IN CIVIL AND ENVIRONMENTAL ENGINEERING, 2010, 223-226 p.Conference paper (Refereed)
    Abstract [en]

    Describing the mechanical parameters of a rock joint with single values is difficult since rock has a natural spatial variation. In addition to this, the interpretation of the results is dependent on the number of tests. Despite this fact, input data for these parameters are often given with a deterministic value. This paper presents the results of fourteen shear tests tested under a constant normal stress of approximately 0.8 MPa. The samples were taken from a slightly weathered rock joint in granite. Basic friction angle and dilation angle, together with shear and normal stiffness, are evaluated. Based on the results, mean values and standard deviations together with coefficient of variations for the different parameters are presented. After that, different statistical distributions for the parameters are compared. Finally, the results are compared against calculated values derived from commonly used equations.

  • 42.
    Johansson, Nils
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    Deponier som gruvor: Förekomst och förutsättningar för att utvinna basmetaller från svenska deponier2014Report (Other academic)
    Abstract [en]

    Ända sedan den första gruvan i de paleolitiska samhällena för 450 000 år sedan (Lewis och Clark, 1964) har människan successivt flyttat metallresurser från jordskorpan in till samhället i byggnader, infrastruktur, produkter och avfallshögar. Det pågår således ett geologiskt skifte (Johansson, 2013), som accelererade i samband med industrialiseringen, där metaller omlokaliseras till den bebyggda miljön på bekostnad av de geologiska reserverna. Vissa forskare menar att människan har blivit en geologisk kraft så till den grad att för vissa metaller som järn och koppar är mängderna jämförbara i samhället med reserverna i jordskorpan (Lichtensteiger, 2002;. Elshkaki et al, 2004; Spatari et al. 2005, Müller et al, 2006; Halada et al, 2009; Johansson, 2013).

    Soptippar, eller mer formellt deponier, är ett av förråden ovanför jordytan som har fått allt mer uppmärksamhet, eftersom de i sin roll av att vara i slutet av materialflödet fångar upp en stor andel av metallerna på ett avgränsat område. Om deponier definieras i vid mening till att inkludera alla former av avfallsupplag, dvs. även till exempel gruvavfall, så återfinns troligen 50 % av alla uppgrävda metaller i dessa inaktiva förråd (Johansson et al., 2013; Kapur, 2006; Graedel and Kapur 2006). Ur ett globalt perspektiv innebär detta att exempelvis mängden koppar i avfallsupplag motsvarar hälften av de kvarvarande mängderna i jordskorpans reserver (Johansson et al., 2013).

    Även om avfallsupplag avgränsas till inflöden av industriellt avfall (exklusive gruvavfall) och hushållsavfall så är metallinnehållet signifikant. Materialflödesanalyser av koppar och järn har påvisat att mellan 10-20 % av metallerna ovanför jordytan finns i dessa förråd (Johansson et al., 2013). Visserligen är deponering av hushållsavfall idag begränsad, men sedan industrialiseringen har deponeringen varit den vanligaste avfallshaneringsmetoden i Sverige. Detta innebär att i stort sett varje by har sin egen soptipp med stora mängder metaller och andra resurser placerade på hög. Uppskattningsvis finns över 4000 kommunala soptippar i Sverige med varierande storlek (Frändegård et al., 2013).

    Vid sidan av kommunala soptippar finns det även industriella soptippar som är placerade direkt i anknytning till en verksamhet. Uppskattningar har antytt att det finns upp till 1000 industriella soptippar i Sverige. Till skillnad från hushållsavfall deponeras fortfarande signifikanta mängder industriellt avfall i form av till exempel schaktmassor och aska (Naturvårdsverket, 2012a). Det saknas dock mer detaljerade studier av mängderna av olika metaller i industriella och kommunala deponier samt de tekniska och institutionella förutsättningarna för att bryta dessa metaller. Kan deponier vara framtidens gruvor?

  • 43.
    Johansson, Nils
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    Omformulera Svensk metallpolitik2015In: Landets Fria Tidning, ISSN 2001-7448, , 1 p.Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    I form av produkter som elektronik, infrastruktur och konstruktionsmaterial, flyttar människan enorma mängder metaller från gruvor i jordskorpan in i våra samhällen. Människan har blivit en geologisk kraft och en del forskare menar att vissa metallmängder i den byggda miljön är jämförbara i storlek med de mängder som finns kvar i jordskorpans reserver. I Sveriges samlade el- och telenät finns till exempel lika mycket koppar som det finns kvar i Aitikgruvan utanför Gällivare, en av Europas största koppargruvor. En stor del av metallerna är alltjämt i användning, men lika stora mängder har förlorats i olika avfallshögar som gruvavfall och soptippar. Utöver återvinningen av metaller från det årliga avfallsflödet, till exempel pantburkar, finns det således en stor potential att uppnå en bättre samhällelig resurseffektivitet. I dagsläget återvinns dessutom endast ungefär hälften av alla metalltyper som samlas in som avfall. Kritiska metaller som sällsynta jordartsmetaller återvinns inte alls, vilket innebär att medan prospekterare letar efter dessa metaller i jordskorpan låter vi de som redan finns nära oss gå förlorade.

  • 44.
    Johansson, Nils
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    Framtidens gruva är hållbar2014In: Svenska dagbladet, ISSN 1101-2412, Vol. 06-24, 1 p.Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Sveriges mineralpolitik är ensidigt fokuserad på att förbättra förutsättningarna för traditionell gruvnäring. Trots det växer intresset för att utvinna metaller från rivna byggnader, omodern teknisk utrustning, soptippar och infrastruktursystem.

  • 45.
    Johansson, Nils
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    Politikerna hämnar metallåtervinning2014In: Avfall och Miljö, ISSN 0284-1827, no 3, 1 p.44-44 p.Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Indirekt stödje staten gruvsektorn med enorma summor pengar varje år. Det leder till ojämna marknadsvillkor och att återvinningsbranschen inte utvecklas i den takt som den skulle kunna, exempelvis via landfill mining.

  • 46.
    Johansson, Nils
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    Defensiv strategi för återvinning av metaller2014In: Svenska Dagbladet, ISSN 1101-2412Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Regeringen satsar på gruvor i stället för återvinning. Mindre än 1 procent av de flesta sällsynta metallerna återvinns när de tas ur drift. I stället hamnar de på soptippar eller i naturen, skriver sju forskare i en slutreplik.

  • 47.
    Johansson, Nils
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Krook, Joakim
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Eklund, Mats
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    The institutional capacity for a resource transition: A critical review of Swedish governmental commissions on landfill mining2017In: Environmental Science and Policy, ISSN 1462-9011, E-ISSN 1873-6416, Vol. 70, 46-53 p.Article in journal (Refereed)
    Abstract [en]

    Recycling of minerals from waste deposits could potentially double the recycling flows while offering an opportunity to address the many problematic landfills. However, this type of activity, i.e., landfill mining, brings many advantages, risks and uncertainties and lacks economic feasibility. Therefore, we investigate the capacity of the Swedish authorities to navigate the environmental, resource, and economic conditions of landfill mining and their attitude to support such radical recycling alternatives towards a resource transition.

    By analyzing three governmental commissions on landfill mining, we show how the authorities seem unable to embrace the complexity of the concept. When landfill mining is framed as a remediation activity the authorities are positive in support, but when it is framed as a mining activity the authorities are negative. Landfill mining is evaluated based on how conventional practices work, with one and only one purpose: to extract resources or remediation. That traditional mining was a starting point in the evaluation becomes particularly obvious when the resource potential shall be evaluated. The resource potential of landfills is assessed based on metals with a high occurrence in the bedrock. If the potential instead had been based on metals with low incidence in the Swedish bedrock, the potential would have been found in the human built environment.

    Secondary resources in landfills seem to lack an institutional affiliation, since the institutional arrangements that are responsible for landfills primarily perceive them as pollution, while the institutions responsible for resources, on the other hand, assume them to be found in the bedrock. Finally, we suggest how the institutional capacity for a resource transition can increase by the introduction of a broader approach when evaluating emerging alternatives and a new institutional order.

    The full text will be freely available from 2019-02-16 11:13
  • 48.
    Johansson, Nils
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Krook, Joakim
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Frändegård, Per
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    A new dawn for buried garbage?: An investigation of the marketability of previously disposed shredder waste2017In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 60, 417-427 p.Article in journal (Refereed)
    Abstract [en]

    This paper examines the market potential of disposed shredder waste, a resource that is increasingly emphasized as a future mine. A framework with gate requirements of various outlets was developed and contrasted with a pilot project focusing on excavated waste from a shredder landfill, sorted in an advanced recycling facility. Only the smallest fraction by percentage had an outlet, the metals (8%), which were sold according to a lower quality class. The other fractions (92%) were not accepted for incineration, as construction materials or even for re-deposition. Previous studies have shown similar lack of marketability. This means that even if one fraction can be recovered, the outlet of the other material is often unpredictable, resulting in a waste disposal problem, which easily prevents a landfill mining project altogether. This calls for marketability and usability of deposited waste to become a central issue for landfill mining research. The paper concludes by discussing how concerned actors can enhance the marketability, for example by pre-treating the disposed waste to acclimatize it to existing sorting methods. However, for concerned actors to become interested in approaching unconventional resources such as deposited waste, greater regulatory flexibility is needed in which, for example, re-deposition could be allowed as long as the environmental benefits of the projects outweigh the disadvantages.

    The full text will be freely available from 2018-05-20 09:49
  • 49.
    Johnson, Kyle D.
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Raftery, Alicia M.
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Lopes, Denise Adorno
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Wallenius, Janne
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Fabrication and microstructural analysis of UN-U3Si2 composites for accident tolerant fuel applications2016In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 477, 18-23 p.Article in journal (Refereed)
    Abstract [en]

    In this study, U3Si2 was synthesized via the use of arc-melting and mixed with UN powders, which together were sintered using the SPS method. The study revealed a number of interesting conclusions regarding the stability of the system - namely the formation of a probable but as yet unidentified ternary phase coupled with the reduction of the stoichiometry in the nitride phase - as well as some insights into the mechanics of the sintering process itself. By milling the silicide powders and reducing its particle size ratio compared to UN, it was possible to form a high density UN-U3Si2 composite, with desirable microstructural characteristics for accident tolerant fuel applications.

  • 50.
    Johnson, Kyle D.
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Wallenius, Janne
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Jolkkonen, Mikael
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Claisse, Antoine
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Spark plasma sintering and porosity studies of uranium nitride2016In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 473, 13-17 p.Article in journal (Refereed)
    Abstract [en]

    In this study, a number of samples of UN sintered by the SPS method have been fabricated, and highly pure samples ranging in density from 68% to 99.8%TD-corresponding to an absolute density of 14.25 g/cm3 out of a theoretical density of 14.28 g/cm3-have been fabricated. By careful adjustment of the sintering parameters of temperature and applied pressure, the production of pellets of specific porosity may now be achieved between these ranges. The pore closure behaviour of the material has also been documented and compared to previous studies of similar materials, which demonstrates that full pore closure using these methods occurs near 97.5% of relative density.

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