Spelling suggestions: "subject:"annan naturresursteknik"" "subject:"innan naturresursteknik""
21 |
Suspended solids and metals in highway runoff : implications for treatment systemsHallberg, Magnus January 2006 (has links)
It is known that traffic is a source of pollutants and that pollutant loads increase with elevated traffic densities. Studies executed in Stockholm, Sweden advocate that highway runoff from roads with an annual average daily traffic (AADT) exceeding 30,000 vehicles need treatment before discharge to the receiving water. It is common knowledge that sedimentation is the most expedient method for stormwater treatment. However, sedimentation units are area demanding and in highly urbanised watersheds the land use is often restricted. Studies have implied the occurrence of first flush, i.e. an initially higher pollutant load in the beginning of the runoff event, in highway watersheds. With an emphasized first flush it would be possible to treat only a part of the total runoff volume reducing the area needed for a sedimentation basin. In general two methods are used to design stormwater treatment ponds. One method is based on the reduced catchment area and pond surface and the other is based on an average runoff volume and a permanent pond volume. The methods are relaying on data from routine monitoring of various treatment systems and suggest removal efficiencies for pollutants. Applying general removal efficiencies for design it can be intricate to estimate an outlet concentration when the specific removal efficiency may be dependent on the initial concentration of the pollutant. Consequently, knowledge of the removal efficiencies dependence on initial concentration would be helpful to optimise stormwater treatment systems. This research has studied runoff from highly trafficated watersheds. The aim has been to evaluate the mass transport, stormwater quality and sedimentation behaviour and their implications for stormwater treatment. The study sites, Eugenia and Fredhäll, are located along the six-lane highway E4 through Stockholm that has an AADT load of 120,000 vehicles and a speed limit of 70 km/h. In lack of a unified definition of first flush the mass transport was studied using the EU directive 1991/271/EEC discharge demand for TSS of 60 mg/l. It was found that for the majority of the runoff events during winter the event mean concentration exceeded 60 mg/l suggesting that the complete runoff volume should be captured during winter. The dissolved concentration of metals showed significant variations between winter and summer, as did the concentration in the particulate matter (mg/kg). It was possible to correlate total metal concentration to total suspended solids with good correlation (r2 >0.90) for the majority of studied metals in winter and summer. The findings would imply that a successful treatment of the studied metal pollutants could be carried out by sedimentation. However, depending on discharge criteria, the elevated levels of dissolved matter, especially during winter, have to be considered with regards to the selection of the appropriate water treatment process. The sedimentation process could be described by a logarithmical function and initial turbidity. Good correlation (r2 >0.90) was indicated between turbidity and TSS. The sedimentation process of the studied highway runoff varied significantly (p<0.05) when elevated levels of NaCl could be found in the runoff. A significant difference (p<0.05) was shown for turbidity and TSS between summer and winter, which was assumed to be related to the use of studded tires. This study implies that the entire runoff volume must be treated and that the use of first flush as a design criterion is less applicable for the winter period. The study implies good correlation between total metal concentration and TSS. In addition the indicated correlation between turbidity and TSS would point to the possibility to use turbidity as a surrogate measurement for TSS and the studied metals. Moreover, the possibility to describe the sedimentation process by the initial concentration of turbidity would infer the utilisation of turbidity as a tool for process control for stormwater treatment systems. In addition, the novel results for the dependence on the sedimentation process could be incorporated in existing models for design of stormwater treatment systems in similar watersheds. / QC 20101115
|
22 |
Suggestion of generic Product Category Rules (PCR) for newbuildingsCabrol, Philippe January 2006 (has links)
This Master Thesis project consists in suggesting generic Product Category Rules (PCR) for newbuildings which will be in line with the requirements of the PCR for building product issued inFebruary 2006 by the Swedish Environmental Management Council. The suggestion for a PCRfor new buildings is meant to provide a structured framework to the real estate professionals fora reliable, comprehensive and verifiable communication of the environmental performance oftheir buildings. Typical examples of possible use of an environmental declaration of a newbuilding would be communication towards authorities, marketing purposes or planningpurposes. This will also allow the authorities to be able to include the environmentalconsiderations inherent to the buildings themselves in the decision-making process for housingdevelopments (in addition to other environmental considerations inherent to the developmentproject such as EIA results for instance).
|
23 |
EVALUATION OF PHOTOGRAMMETRIC TOTAL STATIONMelesse, Fentaw Degie January 2015 (has links)
Photogrammetry is a science which obtains reliable measurements by a means of pho-tographs, and it can be aerial or terrestrial. This study is done in KTH main Campus on L building located at Drottning Kristinas väg 30. It assessed the precision of Trim-ble total station S8 for photogrammetric point measurement relative to the coordi-nates measured with a total station. The steps performed in the study were: planning the measurements (selection of the study area, selection of the instruments, selection of the station points, selection of the software and putting the target points over the facade), data acquisition and finally data processing in TBC software. In the work, sys-tematic error tests were carried out, and the tests results show that there are systematic errors in easting and northing of the measurement result, however it was difficult to say there is or there is no systematic error in the elevation. The most likely source of these errors might be an incorrect orientation of the camera. It was seen that there were some factors influenced the precision of photogrammetric point measurements, such as image redundancy and parallax angle between images. The precision assess-ment was done by calculating photogrammetric points; from different parallax angles between images and from different numbers of images which were taken from differ-ent station points. The better results or smaller differences between the total station and photogrammetric coordinates were detected from five station points relative to four and three station points and from parallax angle in range 60-105 degree relative to parallax angles in range 30-60 and 0-30 degrees. In general, precise photogrammet-ric coordinates were obtained from parallax angle in range 60-105 degree and from five station points.Keywords: Photogrammetry; precision; station points, checkpoints, Trimble total sta-tion, Trible Business Center.
|
24 |
Vattengeokemi och syre-väteisotoper som verktyg för spårning av vattenkällor vid vattentäkter : En fältstudie vid Gäddviksområdet i LuleåEriksson Solander, Viktor January 2020 (has links)
Groundwater is an important source of drinking water where advanced knowledge in the area is of great importance in order to ensure the drinking water quality for future generations. Groundwater is chemically complex because it is formed from a large variety of water sources where the water comes from and passes through different geological and hydrological environments. Environmental forensics is an important area in environmental studies where a wide variety of analytical techniques are integrated to be able to trace and identify sources of pollution. In the Gäddvik project, environmental forensics is applied as a method for tracking pollution in naturally occurring waters. Concentrations of selected elements, oxygen- and hydrogenisotopes and cerium-anomalies have been used to show chemical differences between different water sources in groundwater reservoirs in the Gäddvik area. A sub-study at Kvarnträsket (a lake located in the Gäddvik area) has been carried out to track surface water intrusion in nearby groundwater used for drinking water. Different types of graphs and charts have been created from data on the area, where these have been used to give a simplified visualization of different geochemical trends for selected elements/isotopes. Quality differences between two nearby groundwater reservoirs have been studied and discovered, where one is Luleå’s main groundwater reservoir and the other is a backup groundwater reservoir. Surface water from the Luleå River has been detected in the main groundwater reservoir to a greater extent than in the backup groundwater reservoir. This may be since the main reservoir is under higher exposure and uses river water for artificial infiltration to the groundwater. Oxygen- and hydrogenisotopes have been shown to be useful for tracking and locating surface water infiltration in groundwater intended for drinking water. / Grundvatten är en viktig källa för dricksvatten där en utvecklad kunskap inom området är av stor betydelse för att kunna säkerställa dricksvattenkvalitén för framtida generationer. Grundvatten är kemiskt komplext eftersom det bildas från en stor variation av vattenkällor där vattnet kommer från och passerar genom olika geologiska och hydrologiska miljöer. Environmental forensics är ett viktigt område inom miljöstudier där man integrerar en bred variation av analytiska tekniker för att kunna spåra och identifiera föroreningskällor. I Gäddviksprojektet tillämpas environmental forensics som metodik för spårning av föroreningar i naturligt förekommande vatten. Koncentrationer av valda element, syre- och väteisotoper samt cerium-anomalier har använts för att visa kemiska skillnader mellan olika vattenkällor vid vattentäkter i Gäddviksområdet. En delstudie vid Kvarnträsket (en sjö belägen i Gäddviksområdet) har genomförts för att spåra ytvattenintrång i närliggande grundvatten som används för dricksvatten. Olika typer av grafer och diagram har skapats från data över området, där dessa har använts för att förenklat visualisera olika geokemiska trender för valda element/isotoper. Kvalitetsskillnader mellan två närliggande vattentäkter har studerats och upptäckts där ena täkten är Luleås huvudvattentäkt och den andra är en reservvattentäkt. Ytvatten från Luleälven har upptäckts i huvudvattentäkten i större utsträckning än reservvattentäkten. En potentiell orsak till detta är att huvudvattentäkten är under högre belastning och använder älvvatten för konstgjord infiltration till grundvattnet. Syre- och väteisotoper har visats användbara för spårning och lokalisering av ytvattenintrång i grundvatten avsedda för dricksvatten.
|
25 |
Implementing Life Cycle Assessment in the Product Development Process : Creating a simplified LCA-tool to support decision making and implement sustainability as a design parameterJohansson, Markus, Sars, Jonatan January 2023 (has links)
Design is described as the main factor influencing a product's sustainability, and with industrial growth, global interest in sustainability issues has also increased. Furthermore, the design process is an important part when companies are to reduce climate impact of their products, and that the demand for more environmentally friendly products is increasing. Due to both an expanded legal framework and increased consumer demand for green products, the concept of sustainable product development has been increasingly established and received greater attention. A method to determine the environmental impact of a product during its life cycle is to perform a life cycle assessment (LCA). However, conducting a LCA requires large amounts of information, information that can often be unreliable and difficult to obtain. For this reason, together with the fact that a LCA is both time-consuming and costly to carry out, there is reason to explore the possibilities for a simplified life cycle assessment (SLCA). The aim of this thesis is to investigate how a SLCA-tool could be created to support decision making in the product development process (PDP). Furthermore, the thesis intends to investigate how a SLCA-tool can be successfully integrated and used, and what role a SLCA-tool have in the PDP process. This tool creation will therefore contribute to more knowledge in the implementation of SLCA in manufacturing companies. A qualitative approach was used to address the aim of the paper. The methodology used was five-folded and included 1) preliminary study, 2) specification, 3) creation of tool, 4) verification of tool and 5) implementation. The creation of the tool was based on the conditions of a multinational company within the manufacturing sector. The results indicate that the user-friendliness of a SLCA-tool should be prioritized over the precision, on the basis that the tool should be used by designers with a mandate to make decisions about the design of a product. A SLCA-tool should therefore mainly focus on the raw material extraction and use phase, as these are the life cycle phases that generally have the highest climate impact, but it should also consider the other life cycle phases of a product. This reduces the number of choices the user has to make. To further help users make sustainability-related decisions in the PDP, a SLCA-tool should help them compare the environmental impact of different design options. Despite the gross simplifications, the evaluation of the developed SLCA-tool shows that the distribution of climate impact between the life cycle phases can largely be the same in a SLCA-tool as in a full scale LCA. By setting sustainability objectives early in the PDP and engaging an early integration of a SLCA-tool, even if the information about the product is initially limited, sustainability can be concretized and become a design parameter like time to market and cost. Through the early integration into the PDP, a SLCA-tool can also be used in a business context in Product Portfolio Management to ultimately develop a sustainable technology portfolio that meets customer needs. The creation of a SLCA-tool, based on company-specific conditions, gives hope for successful implementation and use, but the tool should also be evaluated after a period of implementation to determine its final effect on decision-making in the PDP. What is also important to consider is that the tool developed in this thesis only takes into account the climate impact, and thus a system perspective should be applied by complementing other ecodesign tools to avoid sub-optimization in decision-making. Furthermore, it should also be kept in mind that the main purpose of a SLCA is to map a product's climate impact and understand how resources can be allocated to reduce the climate impact of a product. If there is an awareness of these conditions, a SLCA-tool can both reduce cost and time, compared to a full scale LCA, to support decision-making in the PDP from a climate perspective.
|
26 |
Artificial neural networks : applications in morphometric and landscape features analysisEhsani, Amir Houshang January 2007 (has links)
In this thesis a semi-automatic method is developed to analyze morphometric features and landscape elements based on Self Organizing Map (SOM) as a unsupervised Artificial Neural Network algorithm. Analysis and parameterization of topography into simple and homogenous land elements (landform) can play an important role as basic information in planning processes and environmental modeling. Landforms and land cover are the main components of landscapes. Landscapes are dynamic systems that involve interrelation between physical characteristics (such as landform, soil) and anthropogenic processes (such as land use). In morphometry (as general term of geomorphometry) - the qualitative and quantitative measurement of topography - morphometric parameters are calculated such as profile curvature and longitudinal curvature. They are then used in morphometric analysis to identify morphometric features like plane, channel, ridge, peak or pit. In February 2000 the Shuttle Radar Topography Mission (SRTM), collected data over 80% of the Earth's land surface, to derive a consistent digital elevation model (DEM) for allland areas between 60 degrees N and 56 degrees S latitude. This DEM with about 90 m grid spacing was used to generate morphometric parameters of first order (slope) and second order (minimum curvature, maximum curvatures and cross-sectional curvature) by fitting a bivariate quadratic surface. These surface curvatures are strongly related to landform features and geomorphological processes. The thesis starts with an overall introduction and literature review. Then two methods for morphometric analysis are compared: morphometric parameterization and feature extraction proposed by Wood (1996a), calculated with Geographic Information Systems (GIS) software and our method implemented with Self Organizing Map (SOM) as an nsupervised artificial neural networks paradigm. Finally in our method for landscape element analysis morphometric parameters and remotely sensed spectral data are combined. The emphasis is on morphologically homogeneous landscape elements characterized by similar slope and curvature conditions. SOM is used to reduce large multidimensional data sets to one output layer consisting of 20 map units. These map units are interpreted in terms of morphometric features, slope and land cover to identify and characterize landscape elements or geoecological units Both studies have demonstrated valuable methods for extraction of land information that can be used in geomorphologic applications and geoecosystem modeling. These methods allow important savings in field work and can be used as alternative to labor intensive manual methods. But results may depend on scale and quality of the DEM and the topographic situation; caution should be used in interpretation. Evaluation of these methods in other areas with different morphometric conditions and with multi-scale DEM remains to be done. / QC 20101104
|
27 |
Varför sorterar inte Lidingöbor ut sitt matavfall? : Matavfallsinsamling för småhushåll på Lidingö / Why do not Lidingö citizens sort out their food waste? : Food waste system for Lidingö householdsBorg, Emelie, Pereira de Moraes, Felicia January 2017 (has links)
Lidingö har sedan 2010 erbjudit sina invånare att bli abonnenter av tjänsten för matavfallsinsamling. Trots årliga kampanjer har de dock inte samma anslutningsgrad som kommuner som har ett taxerings - och insamlingssystem som fungerar på liknande sätt. Syftet med detta arbete är därför att svara på; Varför sorterar inte småhus ut matavfall i Lidingö stad trots att det finns förutsättningar för det? Genom litteraturstudier och utskickad enkät till boende på Lidingö har anledningar till varför majoriteten av småhus-hushållen inte är abonnenter tagits fram samt vilka åtgärder som Lidingö stad kan bistå med för att få fler av dessa att bli abonnenter. Det som identifierades som anledningar till att Lidingöbor inte sorterar var främst att de var oroliga för lukt, de hade för lite matavfall och de saknade information. Kampanjer som ansågs fungera väl genom resultat från litteraturstudier i beteendeförändring och jämförelse med andra kommuner var att använda informatörer eller dörrknackare samt att involvera boende i funktionen och driften av systemet. De slutgiltiga åtgärdsförslagen till Lidingö var att synliggöra information bättre och på ett sätt som får de boende att känna sig personligt engagerade till att sortera samt att minska trösklarna i systemet. / Lidingö has since 2010 offered residents to become subscribers of the food waste collection service. Despite annual campaigns they do not have the same connection rates as municipalities that have a taxation and collection system that works similarly. The purpose of this work is therefore to answer; Why does not single-family houses sort out food waste in Lidingö stad despite they have the conditions to do it? Through literature studies and a questionnaire sent to residents in Lidingö, reasons have been identified as for why the majority of small-family households are not subscribers, and what means Lidingö stad can use to get more subscribers. What was identified as a reason why citizens of Lidingö did not sort was primarily that they were worried about smell, they had too little food waste and they lacked information. Recommended campaigns that were identified through results from literature studies in behavioural change and comparison with other municipalities are; use informers or door-stepping and involve residents in the functioning and operation of the system. The final action proposals for Lidingö stad is to make information better visible and in a way that makes the residents feel personally involved in sorting and reducing the thresholds in the system.
|
28 |
Carbon Neutral Road Transportation : An Assessment of the Potential of Electrified Road SystemsMöller, Clemens January 2017 (has links)
Sweden is striving towards a carbon neutral transportation sector by2030 which includes reductions from CO2 emissions by 70%. This thesis focusses especially on the decarbonization of road freight transportation. Even though electrification of vehicles is seen as one of the available options to reach this goal, present battery technology does not meet requirementsof energy density and cost. The electrification of roads with electrified road systems (ERS) enables vehicles to charge electrical energy while in motion and has the potential toreduce weight and costs of on-board batteries for electric vehicles and avoids range anxiety of vehicle operators. Within this Master’s thesis, available ERSs are assessed and it is shown which of the available systems performs best in selected categories. Furthermore, alterantive options for large CO2 emission reductions in the roadtransportation sector are evaluated and it is shown that ERSs constitute the most promising alternative. Results of this dissertation are based on a qualitative research approachand limited to data availability.
|
29 |
Key factors for introducing an improved climate adaptation for engineers and contractors working in multidisciplinary infrastructure projects / Nyckelfaktorer för att införa en förbättrad klimatanpassning för ingenjörer och entreprenörer som arbetar i multidisciplinära infrastrukturprojektSandra, Gustafsson January 2018 (has links)
Climate change poses a critical threat to future development and is a reality that affects our society, our way of thinking and acting. The international body has taken common position against climate change in the expression of, inter alia, the Paris Agreement on climate change and the Sustainable Development Agenda. Likewise, the Swedish Government’s is aiming for climate neutrality by 2045. This in parallel to the fact that public awareness and knowledge of sustainability grow, the pressure to deliver environmentally friendly, ethical, and economically profitable products increases. The increased pressure on organizations within both public and private sectors leave no opportunity to escape as everyone is required to assist against the common goals. For organizational survival, it is thus important to find new ways of tying societal improvement with business, calling for new forms of knowledge and competence. Infrastructure investments play a fundamental function to achieve sustainable development and empower communities as they enhance economic growth, reduces inequality and improve the quality of life. Simultaneously, the climate impact from construction, operation, and maintenance of infrastructure is significant. Knowledge, practical advice and guidance to cope with increased requirements for reducing greenhouse gas emissions are available. In addition, awareness of the need for systematic climate work has increased in line with the introduction of new requirements and guidelines. Nevertheless, the climate perspective is still not a natural part of the mindset and process and the level of achievement of climate-related goals can be considered too low This study aims at investigating how climate mitigation practices can be updated to truly facilitate and enable integration of a climate perspective into the work of designers and contactors working in multidisciplinary infrastructure projects. The study was conducted in the context of a large infrastructure project concerning the construction and expansion of a significant railway segment in Sweden. Among other things, the project include construction of a tunnel in a highly demanding environment involving major climate challenges and a number of aggravating factors. By studying practices, collaborations, and use of external expertise in parallel with how projects proceed and actors operate the study contributes with deeper understanding of existing challenges and key factors for improved integration. The study's analyzed results indicate a number of contributing factors that complicate integration of a climate perspective, among others lack of ownership and risk-taking of the process, lack of knowledge, time and feedback, structural barriers, skepticism, inadequate communication, etc. The conclusion provides four recommendations for further addressing the matter: new contract and procurement models, development of educational packages, review and develop the toolbox of designers and engineers, and evaluate existing practices. / Klimatförändringar utgör ett centralt hot mot vår framtida utveckling och är en realitet som påverkar vårt samhälle, sätt att tänka och agera. Världssamfundet har tagit gemensam ställning mot klimatförändringar i uttryck av bland annat Parisavtalet. Likaså har den svenska regeringen stiftat mål om klimatneutralitet år 2045. Detta parallellt med att allmänhetens ökade medvetenhet och kunskap om hållbarhet, ökar pressen att leverera miljövänliga, etiska och ekonomiskt lönsamma produkter. Den ökade pressen på organisationer inom både den offentliga och privata sektorn lämnar inget utrymme att ducka, eftersom alla är skyldiga att sträva mot de gemensamma målen. För organisatorisk överlevnad är det således viktigt att hitta nya sätt att kombinera samhällsnytta med företagsamhet vilket ökar efterfrågan av kompetens och kunskap inom området. Att investera i infrastruktur är en grundläggande funktion för att främja hållbar utveckling och stärka samhällen, eftersom det bidrar till ökat tillväxt, jämställdhet och förbättrad livskvalité. Samtidigt är klimatpåverkan från byggnation, drift och underhåll av infrastruktur betydande. Kunskap, praktiska råd och vägledning för hantering av ökade klimatkrav för minskade utsläpp av växthusgaser finns tillgängliga. Därtill har medvetenheten om behovet av systematiskt klimatarbete ökat i linje med att nya krav och riktlinjer introducerats. Trots detta, är klimatperspektivet fortsatt inte en naturlig del av tanke- och arbetsprocessen och nivån på uppnående av klimatrelaterade mål kan anses vara för låg. Denna studie syftar till att undersöka hur tillämpade arbetssätt kan uppdateras för att underlätta och möjliggöra integration av ett klimatperspektiv hos projektörer och entreprenörer som arbetar i multidisciplinära infrastrukturprojekt. Studien genomfördes i samband med ett stort infrastrukturprojekt som avser byggnation och utbyggnad av ett i Sverige betydande segment järnväg. Bland annat involverar projektet byggnation av en tunnel i en krävande miljö vilket medför stora klimatutmaningar och ett antal försvårande faktorer. Genom att studera tillämpade arbetssätt, samverkan och användning av extern expertis parallellt med hur projekt fortgår och aktörer arbetar bidrar studien med djupare förståelse av befintliga utmaningar och nyckelfaktorer för förbättrad integrering. Studien ger rekommendationer för vidare behandling av frågan. Studiens analyserade resultat indikerar ett antal bidragande faktorer som försvårar integreringen av klimatfrågan, bland annat bristande ägandeskap och riskupptagande i processen, bristande kunskap, tid och återkoppling, strukturella hinder, skepsis och bristfällig kommunikation. Studiens slutsats ger fyra rekommendationer för vidare arbete: nya kontrakts- och upphandlingsmodeller, utveckling av utbildningspaket, granskning och utveckling av verktygslådan till konstruktörer och ingenjörer samt utvärdering av befintliga arbetsmetoder.
|
30 |
Ageing behaviour of steel slags in landfill linersDiener, Silvia January 2009 (has links)
Steel slags are by-products of the steelmaking process. To avoid unnecessary disposal, e.g. into landfill, their chemical and physical properties should be exploited to support alternative uses. Steel slags can be recycled within the steel plant or used as construction material in roads, hydraulic engineering and different types of barriers, including landfill covers. A landfill cover consists of several layers, including a liner with low water and gas permeability in order to reduce methane and leachate emissions. Several studies have demonstrated that steel slags have good potential to fulfil such an application. However, there are questions regarding the stability of the slag minerals over long periods of time. A landfill cover must function well for many decades and centuries. In order to predict the long-term stability of steel slags as a landfill liner, laboratory experiments have been performed to study the effects of accelerated ageing of steel slag under controlled conditions. The factors investigated in the storage atmosphere were carbon dioxide content, relative humidity and temperature. The influence of leachate contact and ageing time were also assessed.This thesis reports the study of electric arc furnace slags and ladle slag from the production of high-alloyed tool steel after accelerated ageing for periods of three months and ten months. Mineralogy and leaching were studied using two different leaching tests, thermal analysis, acid-neutralization capacity assays and X-ray diffraction. For the ageing periods considered, the exposure of the slags to an atmosphere enriched with carbon dioxide had the greatest impact on leaching. In general, calcium, aluminium, sulphur and sodium leached from the slag matrix to the greatest extent while other metals such as chromium, nickel, lead and zinc were found at very low levels in the leachate. The leaching of calcium and aluminium reduced with increasing carbon dioxide level. Thermal analysis revealed the decomposition of carbonates. Weight and enthalpy changes were evaluated between 100 and 1000 °C. The buffer capacity of the steel slags, represented by the acid neutralization capacity (ANC 4.5) was not reduced after 10 months of ageing. However, the division of the titration into two steps revealed a shift of buffering zones for more highly aged samples, probably due to the formation of carbonates. The mineralogy of the investigated steel slags was complex with a large variety of mineral phases, principally calcium silicates, monticellite, periclase and a spinel phase. Other possible phases were gehlenite, merwinite, akermanite and iron. The existence of different solid solution is likely among the slag phases and can cause shifting of peaks in the X-ray diffractogram. Also, calcite was identified. Short-term carbonation has not shown significant impact on mineralogy despite of calcite formation. The results of the study contribute to a better understanding of the chemical and mineral stability of electric arc furnace slag and ladle slag in the environment of a landfill liner. The consequences of slag ageing include reduced leaching rates for certain elements. To predict the long-term behaviour of aged slag, the results of this study should be combined with data from two other sources - an ongoing ageing experiment that includes mechanical tests and a full scale field test at the Hagfors landfill. Additional analytical methods that can better characterise the mineralogy, for example scanning electron microscopy (SEM) and energydispersive X-ray spectroscopy (EDX), should also be applied to better quantify the mineralogical phases and to determine which trace elements are most abundant in specific minerals. / Stålslagg är en restprodukt som kommer från ståltillverkningen. Den har kemiska och fysikaliska egenskaper som bör utnyttjas och som gör den lämplig för återanvändning, samtidigt som onödig deponering kan undvikas. Stålslagg kan återanvändas inom ståltillverkningen eller så kan den användas som konstruktionsmaterial i väg- och vattenbyggnadskonstruktioner eller i olika typer av barriärkonstruktioner som till exempel deponisluttäckningar. En deponisluttäckning består av flera skikt där tätskiktet ska ha en låg vatten- och gaspermeabilitet för att minska metan- och lakvattenutsläpp. Flera studier visar att stålslagg uppfyller dessa egenskaper och har potential att kunna användas i deponitäckning. Men det finns fortfarande oklarheter angående slaggmineralernas stabilitet över en längre tid. En deponitäcknings funktion förväntas vara stabil i många tiotals eller hundratals år. För att kunna förutsäga det långsiktiga beteendet för stålslagg i ett tätskikt genomfördes ett laboratorieexperiment vars syfte var att studera effekterna av accelererad åldring under kontrollerade förhållanden. De faktorer som studerades var koldioxidhalten, relativa luftfuktigheten, temperaturen, kontakten med lakvatten samt åldringstiden. I denna avhandling presenteras undersökningen av ljusbågsugnsslagg och skänkslagg, från framställning av höglegerat verktygsstål, efter tre respektive tio månaders accelererad åldring. Mineralogin och lakningsegenskaperna studerades genom två typer av laktester, termiska analyser, analys av syraneutraliserande kapacitet samt röntgendiffraktion. För de studerade åldringstiderna var det exponeringen av stålslaggen för en koldioxidrik atmosfär som hade den största inverkan på lakningsegenskaperna. Kalcium, aluminium, svavel och natrium var de ämnen som uppvisade den högsta utlakningen från slaggen medan metaller som krom, nickel, bly och zink endast fanns i väldigt låga koncentrationer i lakvattnet. Utlakningen av kalcium och aluminium minskade med en ökande halt av koldioxid. Termiska analyser visade på en nedbrytning av karbonater. Vikt- och entalpiförändringar mellan 100 och 1000°C utvärderades. Stålslaggens buffertkapacitet, representerad av den syraneutraliserande kapaciteten (ANC pH 4,5), reducerades inte efter tio månaders åldrande. Däremot visade uppdelningen av titreringen i två steg på en förskjutning av buffertområdena för de prover som åldrats tio månader, förmodligen på grund av karbonatbildning. Mineralogin för de undersökta stålslaggerna var komplex med en stor variation av mineralfaser, främst kalciumsilikater, monticellit, periklas och en spinellfas. Andra möjliga mineralfaser var gehlenit, merwinit, åkermanit och järn. Förekomsten av olika fastfaslösningar i stålslaggsmineralerna är sannolik vilket kan orsaka förskjutningar av topparna i diffraktogrammen. Kalcit identifierades också. Karbonatisering under en kort tid visade sig inte ha någon signifikant inverkan på mineralogin, förutom en viss kalcitbildning. Resultaten från studien bidrar till en bättre förståelse av stabiliteten för ljusbågsugns- och skänkslagg i den miljö som finns i ett tätskikt. Åldringen av slaggen resulterade i en reducerad utlakning av vissa element. För att kunna förutsäga det långsiktiga beteendet för åldrad slagg bör resultaten från den här studien kombineras med data från ett pågående åldringsförsök som inkluderar mekaniska tester samt ett fullskaligt fältförsök på Hagfors deponi. Analysmetoder som mer detaljerat kan karaktärisera mineralogin, till exempel svepelektronmikroskopi (SEM) och energidispersiv röntgenspektroskopi (EDX), bör också användas för att bättre kunna kvantifiera mineralfaserna och bestämma vilka spårelement som är vanligast i specifika mineraler.
|
Page generated in 0.1634 seconds