Cancrinite specimens from Ontario were studied. Chemical and thermogravimetric analyses were made. Non-Bragg reflections were observed in x-ray photographs. These reflections have the same symmetry as the main lattice reflections, but the intensities, abundance and the relative positions of them with respect to the main lattice reflections are different from one specimen to another. In the heated specimens, the superstructure reflections decrease in intensities, shift in position and are streaked in a direction parallel to the a*-axis on the a* c* reciprocal lattice plane. Phase changes in the heated cancrinites show that the sodalite group of minerals occur as transitional phases in the cancrinite break down reactions. It is shown that the non-Bragg reflections are very similar to the main lattice reflections. There is a probable relation between the non-Bragg reflections in cancrinite and the sodalite group of minerals. / Thesis / Master of Science (MSc)

The Ditrău Alkaline Massif (Romania) is located in the Eastern Carpathians, as an intrusion in the Bukovina nappe system of the Mesozoic crystalline zone. Nepheline syenites are the most abundant rocks occurring in the central and eastern part of the Massif, and represent the youngest intrusion of the complex. Petrographic observations and fluid inclusion studies were performed on nepheline syenites in order to examine the evolution and the effect of the magmatic fluids on the alteration of nepheline to secondary minerals as sodalite, cancrinite and analcime. Fluid inclusion studies in nepheline, aegirine, albite and cancrinite provide evidence for the role of highly saline fluids in incongruent transformation reactions by which sodalite, cancrinite and analcime crystallize mostly on the expense of nepheline. The fluids, in most cases, can be modeled by the H2O-NaCl system with various NaCl contents; however inclusions with more complex fluid (containing also K, Ca, CO3, etc. besides H2O and NaCl) composition are abundant. Raman spectroscopic studies of daughter minerals in inclusions demonstrate the presence of alkali-carbonatic fluids in some of the earliest inclusions of nepheline, aegirine and albite. The alteration process is supported by the presence of H2O-NaCl fluid inclusions in cancrinite, showing lower salinity compared to those in nepheline. During the crystallization period of the nepheline syenites the rock was in equilibrium with a high salinity, carbonate rich solution that evolved to decreased salinity with time. The following observations support this: • paragenesis of mineral phases and their fluid inclusions: the early phases have high salinity inclusions and the late phases have low-salinity inclusions • the partitioning of chlorine depends on the pressure of the system: at about 2.0 kbars, the fluids coexisting with the melt have a high initial salinity and the salinity decreases with time; inclusions in nepheline show the lowest trapping pressure at ~2.5 kbars, hence the system has a high initial salinity and decreases with time • aH2O increases with time, resulting in the formation of H2O-bearing phases in a late stage of the crystallization of nepheline syenites. / Master of Science

Philosophiae Doctor - PhD / In South Africa, almost 90 % of the country’s electricity is generated from coal combustion. This reliance on coal for energy production is projected to continue in the near and medium term due to the increasing demand for industrial and domestic energy. During coal combustion, a large quantity of fly ash is produced as the main waste product and in South Africa approximately 36 - 37 million tons of fly ash is produced on a yearly basis. The management of huge quantities of fly ash has been and still is a continuing challenge that requires urgent intervention. In this regard, there exists an urgent need to maximize fly ash beneficiation, thus forming the motivation for this research. The overall objectives of this thesis was to synthesize high pure phase zeolites A and X from South African fly ash, study their formation mechanism, and explore the potential of mine waters during the synthesis process as well as developing new and efficient zeolite synthetic protocols by the use of ultrasound. In order to address these objectives, the research was designed in a sequential manner so that the preceding results could act as a platform for the attainment of the next objective. In this case, the identification and optimization of synthesis conditions for producing zeolite A and X acted as a basis for understanding the influence of use of mine waters as a substitute for pure water. This further laid the foundation for the in-situ ultrasonic monitoring of the formation process of zeolite A and X from fly ash. The final stages of the study involved use of ultrasonic energy as an ageing tool to improve the conditions obtained during the hydrothermal synthesis of zeolite A as well as investigate the potential to synthesize zeolites directly by use of ultrasound without the need for the fusion, aging or conventional hydrothermal treatment step. The result of the optimized synthesis conditions for producing zeolite A starting either from clear extract of fused fly ash or unseparated, fused South African class F fly ash slurry were molar regimes of 1 Al2O3 : 30.84 Na2O : 4 SiO2 : 414.42 H2O or 1 Al2O3 : 5.39 Na2O : 2.75 SiO2 : 111.82 H2O respectively and at a hydrothermal synthesis temperature of 100 °C for 2 hours. The optimized procedure was simple, efficient and resulted in a considerable improvement of the quality and phase purity of the zeolite A product when the clear extract of fused fly ash was used instead of starting from unseparated, fused fly ash slurry. On the other hand, the optimized synthesis conditions for preparing the typical octahedral shaped zeolite X from South African fly ash was found to be a molar regime of 1 Al2O3 : 4.90 Na2O : 3.63 SiO2 : 115.92 H2O at a hydrothermal synthesis temperature of 80 ºC for hours.