[Truncated abstract] As mineral deposits continue to be mined, the non economic gangue materials such as sulphides (e.g. pyrite) that are extracted as part of the ore body or overburden are deposited within the waste rock and/or milled tailings. As a result of natural weathering processes, these reactive materials represent a potential hazard to surrounding environments. A major consequence, resulting from mine-waste impoundments containing sulphidic materials, relates to the offsite movement of low pH leachates containing elevated concentrations of metal ions posing a contamination threat. The processes and mechanisms acting in the formation of acid mine drainage (AMD) are highly variable and, to a high extent, controlled by climatic conditions as the main driver of water flow and wetness of the system which in turn determines the availability of oxygen as well as water for pyrite weathering. In particular, this thesis is based on the hypothesis that in semiarid and arid climates the acid production may be water … The experiments were repeated at different water contents ranging from 0.24 to 0.33 cm3 cm-3. Breakthrough curves (BTC) of Li+, K+, Ca2+, Mg2+, Na+ and pH were measured and described with models of different complexities. This included the use of a simple linear and non-linear isotherms for Li+ alone, a binary Li+ - K+ ion exchange, and a complete multicomponent chemical equilibrium description of ion transport. The latter, by including dissolution of primary minerals which released base cations such as Mg2+, Ca2+ and K+ explained some of the elution patterns of base cations for which the Li+ - K+ exchange was the dominant process. Furthermore, under unsaturated water flow conditions, retardation of Li+ increased with decreasing water content. Thus solute mobility in mafic rock tailings appears to decrease under strongly unsaturated water flow conditions.

No description available.

M.Tech. (Architectural Technology) / The architectural intervention proposes an urban redevelopment along the mining belt of the city of Johannesburg through the treatment of acid mine drainage. The design research includes a network of selected sites located along the Johannesburgmining belt to address the problem of acid mine drainage,as well as to provide solutions for future urban environments. The main solutions to eradicate the acid mine water problem are infrastructural, which in most cases is associatedwith inhumane environments. A design question addressing the marriage between harsh infrast ructure and humane environments is therefore dealt with ,in an attempt to create a self-sustaining architecture in which infrastructure can have an integrative urban function for the future . The dissertation aims to achive a design intervention that will thread the traces of a mining century into this contemporary African city, through an architecture that will grow into the future of the ever-changing and continuously emergent Johannesburg.

Ekobacken, Värmdö kommun, har problem med surt yt- och grundvatten med höga metallhalter. Uppmärksamheten har riktats mot berggrunden som krossats och lagrats i deponihögar. Bildningen av sur lak styrs av flertalet geokemiska egenskaper, bland annat vilka sulfidmineral som förekommer och deras kristallstruktur. Prover från Ekobacken har undersökts utifrån sulfidhalt, kristallarea för opaka mineral och surgörande potential för att kunna utröna om ett samband finns mellan kristallareafördelning och lakningsegenskaper. Proverna har mikroskopiskt undersökts i reflekterande ljus för att skilja ur vilka opaka faser som förekommer samt har tunnslip fotograferats för att bildanalysera de opaka faserna utifrån area och form. Ett statiskt laktest utfördes på proverna för att kvantifiera dess lakningsegenskaper. Resultatet visar att bergarterna bestod i stor del av kvarts, fältspat och biotit i olika fördelningar. Opaka faser som förekom var pyrit, grafit, kopparkis och magnetit. Bergarterna visade sig generellt ha hög sulfidhalt från ABA resultatet, där ett prov hade en halt på 0,61 vikt%, medan andra prov hade relativt hög bufferförmåga och därför ingen surgörande potential. Proverna som undersöktes visade sig vara likartade varandra i förhållande till kristallareafördelning av opaka faser och form. I den här studien gick ingen direkt korrelation mellan provens kristallareafördelning för opaka faser och lakningspotential att utröna / Ekobacken, Värmdö municipality, have a problem with acidic surface- and groundwater with high metal content. The attention has been directed towards the bedrock which have been crushed and stored in landfills. The production of acid drainage is controlled by multiple geochemical properties inter alia which sulphide minerals are present and the structure of crystals. Samples from Ekobacken has been collected and analysed for sulphide content, crystal-area of sulphide minerals and acidic potential to investigate if there is a correlation between crystal-area distribution and leachability. The samples were examined under reflective light microscopy to determine the different opaque phases present and the thin sections were photographed for a photo analysis regarding crystal area and shape. A static leachability test was performed to be able to quantify the samples potential to produce acidic drainage. The results show that the samples contained mostly quartz, feldspars and biotite. Opaque phases present were pyrite, graphite, chalcopyrite and magnetite. ABA results showed high sulphide content, where one sample reached 0,61 wt. % sulphide content. Other samples contained relative high ability to buffer acidic reaction and thus showed no potential to produce acidic drainage. The samples were homogenous to each other with regard of crystal-area distribution of opaque phases and aspect-ratio of individual crystals and in this study no direct correlation between the sample’s crystal-area distribution of opaque phases and potential to produce acidic drainage was apparent.

Les interactions entre des gouttes ou des bulles sont rencontrées dans de nombreuses applications industrielles et/ou environnementales. Ici, nous nous intéressons à l’électro-coalescence qui a des applications importantes comme par exemple la séparation eau/pétrole (coalescence de gouttelettes d'eau dans du pétrole). L’étude a été consacrée à l’élaboration et à la mise point de modèles basés sur les équations de Navier-Stokes et les équations régissant les champs électriques au niveau d’une seule goutte ainsi que l’interaction entre deux gouttes et plus particulièrement l’effet des forces hydrodynamiques et électrostatiques sur le mécanisme d’amincissement du film séparant les deux gouttes. Selon les cas traités, le suivi de l’interface est réalisé soit à l’aide de la méthode LS (Level Set) ou bien à l’aide de la méthode MM (Moving Mesh). Les solutions numériques ont été obtenues à l’aide du code de calcul COMSOL Multiphysics. Dans une première étape, nous avons analysé l’effet d’un champ électrique sur la déformation d’une seule goutte suspendue dans un autre fluide visqueux, pour différentes propriétés physiques et électriques des deux fluides. Le modèle a été testé et validé par confrontation avec les solutions analytiques existantes et avec des études numériques de la littérature. Nous avons examiné aussi l’influence du champ électrique sur la génération d’une goutte secondaire lors de la coalescence entre une goutte et une interface liquide-liquide déformable. Dans une seconde étape, nous avons étudié le drainage et la déformation de deux gouttes en interaction sous l’action d’une force constante. Contrairement à la théorie de lubrification basée entre autre sur l’hypothèse d’une petite déformation de l’interface, aucune hypothèse simplificatrice n’a été utilisée pour la résolution des équations, ce qui a permis d’obtenir des solutions numériques aussi bien pour les petites que pour les grandes déformations. Dans une troisième étape, nous avons examiné l’ascension d’une goutte isolée ou de deux gouttes de n-butanol dans l’eau sous l’influence de la force de flottabilité. L’évolution des vitesses terminales d’ascension des gouttes (goutte de tête/goutte suiveuse) et le drainage du film séparant les deux gouttes ont été analysées en présence et en l’absence de champ électrique. / Drops and bubbles interactions are encountered in various industrial and environmental applications. In this work, we focus on the electro-coalescence which has important industrial uses such as the destabilization of water / oil emulsions (coalescence of water droplets in oil). This study was devoted to the development and the elaboration of numerical models based on the Navier-Stokes equations and those describing the electrical field on a single drop as well as the interaction between two drops, and more particularly the effect of hydrodynamic and electrostatic forces on the thinning mechanism of the film separating the two drops. According to the treated cases, the interface tracking is achieved either by using the LS method (Level Set) or using the MM method (Moving Mesh). Numerical solutions were obtained using the commercial CFD software COMSOL Multiphysics. During the first step, we analyzed the effect of an electrical field on the deformation of a single suspended drop in another viscous fluid, for different physical and electrical properties of the two fluids. The model was tested and validated by comparison with existing analytical solutions and numerical studies found in the literature. We also analyzed the influence of the electric field on the generation of a secondary drop during the coalescence between a drop and a deformable liquid-liquid interface. In a second step, we investigated the drainage and deformation of two drops in interaction under the effect of a constant force. Unlike the lubrication theory which is based among others, on the assumption of a small interface deformation, in this work, no simplifying assumptions were used for the solution of equations, which allowed us to obtain numerical solutions for both small and large deformations. For the third step, we examined the rise of two drops of n-butanol in water under the influence of buoyancy force. The evolution of the drops terminal ascension velocity (leading drop/trailing drop), and the drainage of the film separating the two drops were analyzed in the presence and in the absence of electrical field.

No description available.

No description available.

published_or_final_version / Public Administration / Master / Master of Public Administration

No description available.

In this diploma thesis the issue of drainage system influence on water regime of catchment area was solved. The aim of the thesis was to analyze influence of drainage system on specific catchment area using mathematical, hydrological and statistical methods. In the teoretical part, the thesis describes the issue of drainage (specifically the drainage system of area of the Czech republic) and the influence of drainage system on water regime. In the practical part an analysis of the catchment area of Kopaninský creek and subcatchment areas P6, P52 and P53 was performed. At all of those areas, certains parts are dewatered by subsurface systematic drainage system, those parts are described in detail. The runoff coefficients and specific runoff from each subcatchment areas in different time interval were calculated and observed. Runoff separation and precipitation-runoff situation analysis were performed. The results are evaulated in the chapter Results and Discussion.