Thesis--University of Missouri, School of Mines and Metallurgy, 1908. / R. E. Hoffman determined to be Ray Eugene Hoffman from "Forty-First Annual Catalogue. School of Mines and Metallurgy, University of Missouri". The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed February 26, 2009)

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Thesis (MTech(Chemical Engineering))--Cape Technikon, Cape Town, 2001 / Although numerous methods exist to treat mine water that is rich in CaS04 they all have inherent disadvantages. A means of treating acid mine drainage is by forming a precipitate known as ettringite. Ettringite is a low solubility calcium hydrosulphoaluminate that is stable between pH values of 11.4 and 124. Ettringite is made up of calcium, sulphate, aluminium and a large amount of water. The formation of this precipitate is a result of calcium sulphate which is brought into contact with an aluminium containing agent. Decomposition of ettringite takes place by reducing the pH to a near neutral value. A 5 stage process is proposed to treat acid mine drainage of which the formation of ettringite forms the cornerstone of this process. The process incorporates the formation of more than one precipitate, namely; metal hydroxides, gypsum, CaS04 and CaCOJ. To facilitate the formation of ettringite, gibbsite is recycled as a result of ettringite being decomposed. The results obtained in this paper are as a result of modeling this process on an Aspen Plus simulator. The simulation package is useful for investigating how this process behaves under non-ideal conditions and under various sensitivities. The process and its behavioral patterns are also analyzed in order to ascertain its economic viability.

Vid produktionsborrning av spränghål kan valet av borrstål för dimensionen ca 70-100 mm variera mellan olika gruvor. Eftersom valet av borrstål har inverkan på mer än den direkta kostnaden finns ett behov att kvantifiera dessa. Examensarbetet syftar till att ge en värdering av för- och nackdelar mellan olika borrstål samt att överblicka nuvarande kostnads- och konsumtionsdata. Målet med arbetet är att kvantifiera behovet av en styvare borrsträng i samband med produktionsborrning med hänsyn till dess kostnadspåverkan. Eftersom en fullständig jämförelse av olika borrstål kräver omfattande fältstudier vilka överskrider den avsatta tiden för detta arbete ligger fokusområdet på deras inverkan på hålavvikelser och mediabehov. Genom att beräkna den spiralformade böjningens kastlängd för de olika borrstålen samt de radiella krafterna och momentkrafterna som verkar på borrkronan till följd av borrsträngens böjning kan borrstålets inverkan på hålavvikelsen identifieras. Mediabehovet, vare sig det är luft eller vatten, påverkas av den fria ytan som uppstår mellan borrstålet och borrhålsväggen. Genom att beräkna förbrukningen kan valet av borrstål motiveras. Resultaten visar tydliga differenser för kritisk last mellan de fyra studerade borrstålen där borrör, oavsett diameter, tål klart högre belastningar. De radiella krafterna och mediabehovet följer samma trend medan momentkrafterna är desamma för samtliga borrstål. Insamlad kostnads- och förbrukningsdata talar för att ingen ekonomisk vinning finns i att använda stänger istället för rör, snarare vice versa. Resultaten talar enhälligt för att långhålsborrning med rör är det bästa alternativet med avseende på hålkvalitet, mediabehov och kostnad. / When drilling blast holes of ca 70-100 mm in diameter with long hole drilling, it´s common to use different types of drill steel. Since the choice has an impact on more than the direct costs, there is a need to quantify the other effects. The sole purpose of this thesis is to give an evaluation of pros and cons for different drill steels and to use current cost and consumption data to dignify this. The goal is to understand the need of an increased stiffness in the drill string during production drilling with regards of their effect on total costs. A complete evaluation of the different drill steels would need extensive field studies which would extend beyond the time frame for this thesis. To accomplish some validated conclusions there´s a need to define a field of focus. This thesis focus on how the choice of drill steel impacts the hole deviation and the use of media. By calculating the helical pitch for the different drill steels, the lateral forces and the bending moment acting on the drill bit, the impact on hole deviation can be identified. The use of media, whether it´s air or water, for sufficient flushing is affected by the cross sectional area between the drill string and the hole wall. By estimating the volume needed for sufficient flushing, the choice of drill steel can be motivated. The results show differences in the applicable critical load for which the drill tubes show bigger capacity. The lateral forces and the use of media follows accordingly whilst the bending moment remains the same for all of the drill steels. Cost and consumption data show that there is no economic gain in using drill rods instead of drill tubes, rather the opposite.    The results are unanimously and supports that using drill tubes is the best alternative with regards to hole quality, use of media and overall costs.

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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. / <p>QC20100709</p>

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[No abstract available] / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

[No abstract submitted] / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The Granduc Mine is near the British Columbia-Alaska boundary in rugged mountainous country about 36 miles northwest of Stewart B.C. The writer participated in detailed surface mapping in the vicinity of the mine during the field season of 1959. Rock specimens were collected in the field and examined microscopically in the laboratory. The results of the latter investigation form the greater part of this thesis. The oldest rocks in the area are north trending, steeply dipping and isoclinally folded metavolcanic and metasedimentary rocks that are believed to be correlative with the Hazelton group. These consist of a basal andesite complex which is overlain by a large thickness of metasedimentary rocks. The Hazelton group rocks have been regionally metamorphosed and synkinematically intruded by small subconcordant bodies of foliated diorite and hornblende granodiorite. The metasediments are believed to have formed from greywackes, marls and sandstones that have been progressively metamorphosed to form schists that can be classified in the quartz-albite-epidote-biotite subfacies of the greenschist facies. Almost identical mineral assemblages are found in the altered dioritic and metavolcanic rocks, and it is concluded that these initially high temperature assemblages have retrogressed during regional metamorphism to attain or approach equilibrium in the same metamorphic facies. At a late stage in the metamorphism strong differential movement was localized in a quartz-rich member of the metasedimentary rocks in a zone near the contact with metavolcanic rocks. All rocks in this zone have undergone retrogressive metamorphism, and have attained equilibrium in the quartz-albite-muscovite-chlorite subfacies of the greenschist facies. Drag folds show that this dislocation metamorphism was related to the formation of an anticlinal structure that lies to the east of the map area. Some of the major structural ore controls appear to have formed at this time. The strongly-developed isoclinal folding was later flexed during or following intrusion of the Coast Range batholith. Ore bearing solutions are believed to have been derived from batholithic emanations and these were channeled along crumpled and brecciated zones that formed during the earlier period of regional metamorphism. Two mineralized zones are present and these are essentially conformable with the metasediments and consist chiefly of chalcopyrite, pyrrhotite and sphalerite. Mineralization has replaced the host rock along favourable lithologic horizons, but appears most heavily concentrated in brecciated zones. The deposit is classified as Mesothermal Replacement. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate