published_or_final_version / toc / Applied Geosciences / Master / Master of Science

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Inductively coupled plasma atomic emission spectrometry has been investigated for solution, slurry and speciation analysis. It has been shown that it is possible to optimise a simultaneous multielement analysis for slurry and solution samples using solid state detection and optimisation algorithms. A range of certified reference materials have been analysed using optimum conditions and results were in good agreement with certified values. Slurry nebulisation has been used for the first time in the analysis of NIST SRM Total Diet' and carbon black samples. Both radially and axially viewed ICP spectrometers were used in these studies. Modifications of the mass transport efficiency of solutions and slurries through the sample introduction system was illustrated upon EIE addition. The transport phenomenon was found to be dependent on the matrix element and not on the analyte of interest. A decrease in transport efficiency was found to be related to the mass of the EIE added. Solution and slurry atom and ion line intensity ratios obtained from an axially viewed ICP were used to illustrate emission enhancement when Mg was used as the thermometric species of interest. Enhancement was found to be spatially dependent and the energy transfer processes governing excitation were modified upon EIE addition. The magnitude of the enhancement effects for solutions and slurries differed, once transport effects had been negated, and this was attributed to variations in atomisation efficiency. A radially viewed ICP spectrometer was also used to monitor the effect of ElEs on solutions and slurries. The Abel integral technique was used to transform lateral profiles and Fe atom line ratios were calculated. 'Real' enhancement effects were apparent upon EIE addition when transport effects had again been negated. The plasma excitation temperature was used as a physical marker to determine the effect of EIE addition on solutions and slurries of Fe. The variation in Texc upon EIE addition was small but showed an increasing trend from Li to Cs. Radially obtained values of Texc were lower than literature values whereas preliminary values obtained axially compared well. It has been demonstrated that transient signal data may be obtained from an array-based spectrometer for speciation studies. The feasibility of reverse phase and size exclusion HPLC-ICP-AES has been demonstrated for the separation of a selection of organosilicon species of various molecular weights. Detection limits were in the range 0.1 to 5 ug ml-1 for a radially viewed plasma. The use of axial viewing when aspirating organic solvents as part of the mobile phase yields higher limits of detection owing to the noise that is measured.

Bentonite/cement grouts and slurries are used in the civil engineering industry in various ground engineering processes. The specifications usually require a minimum compressive strength or shear strength at 28 days age. The interaction between the materials namely bentonite, cement and water is complex; both the bentonite content and the cement content of the grout affect the development of shear strength. An investigation of the development of shear strength has been made for a range of grouts with bentonite contents from 5% to 20% by weight of water and water/cement ratios from 4 to 12. The shear strength was measured at various ages up to 336 days age using a Pilcon hand held shear vane tester, for many grout mixes the shear strength was still increasing at 336 days age. Two mixes were placed in vertical plastic pipes in order to investigate how shear strength may vary with depth in a ground borehole. A mathematical model has been developed to predict the shear strength of any grout mix at any age within the range studied, the model comprises a simple equation with two coefficients A and B which can be obtained from contour plots depending on the mix proportions. The model has been tested using four mixes different from those use to derive the model; statistically there is no significant difference between the actual and predicted results and the model can be used with reasonable confidence.

Thesis (M.S.)--Ohio University, June, 1987. / Title from PDF t.p.

Thesis (M.S.)--Ohio University, November, 1994. / Title from PDF t.p.

M.Ing. (Electrical and Electronic Engineering) / An extensive literature survey revealed that the existing process design methods for specifying the power requirements of industrial mixers depended either upon an assumption of laminar flow conditions, or on a comparison with a Newtonian liquid, or both. In fact, real industrial mixers often experience flow regimes ranging from laminar near the walls of the vessel to fully turbulent in the impeller zone. Moreover, industrial liquids are rarely Newtonian in character. A method of torque monitoring is proposed for fully describing the power requirements of an industrial mixer to suspend a mineral slurry. This method, by incorporating a critical dimension, the impeller diameter, is suitable for scale-up. It was tested in a uranium leaching application with good results. The "comparative viscosity" of the slurry can also be derived. This parameter is suitable for process control purposes.

In this study, slurry availability and the extent of the slurry mixing (i.e., among fresh slurry, spent slurry, and residual rinse-water) were varied via three different injection schemes. An ultraviolet enhanced fluorescence technique was employed to qualitatively indicate slurry availability and its flow on the pad during polishing. This study investigated standard pad center area slurry application and a slurry injection system (SIS) that covered only the outer half of the wafer track. Results indicated that the radial position of slurry injection and the alteration of fluid mechanics by the SIS played important roles in slurry mixing characteristics and availability atop the pad. Removal rates were found to decrease with slurry availability, while a higher degree of slurry mixing decreased the fraction of fresh slurry and consequently lowered the removal rate. By using a hybrid system (i.e., a combination of slurry injection via SIS and standard pad center slurry application), the polishing process benefited from higher slurry availability and higher fraction of fresh slurry than the conventional pad center slurry application and the shorter SIS, individually. This work underscores the importance of optimum slurry injection geometry and flow for obtaining a more cost-effective and environmentally benign chemical mechanical planarization process.

An experimental method was developed for characterizing time-dependent slurries of elongated particles in a coaxial cylinder viscometer which has a wide gap between the inner rotating cylinder and the stationary cup. A model slurry system was studied; it consisted of a dispersed phase of regularly sized nylon fibers and a dispersing medium of an aqueous solution of polyethylene glycol with dextrose and sodium chloride, each of whose effects on the time-dependent nature of the slurry could be examined separately. The slurry gelled in the viscometer on standing. The time-variation of shear stress exerted on the wall of the inner cylinder rotating at a constant angular velocity was recorded as a stress decay curve. It was found that only a part of the gap between the cylinders of the viscometer flows under shear, and that the thickness of the flowing layer increases with time and approaches an equilibrium value. The time-variation of the thickness of the flowing layer Rx(t) as well as the shear stress decay was measured for fifteen slurries. An empirical reaction-rate type model was constructed for the time-variation of the thickness of the flowing layer Rx(t). A second order-zero order reversible reaction model fitted the experimental data well. The three fitting factors of the model were the equilibrium value of the thickness of the flowing layer Rx∞, and the two rate parameters kf/B and B/A. These factors (Rx, Kf/B, and B/A) were correlated with particle length-to-diameter ratio, volume fraction of particles in the slurry, and angular velocity of the rotating cylinder. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Unknown

M.Ing. / Please refer to full text to view abstract