Chapter One, the Introduction, provides a review of the three main areas of the project i.e. slate, pyrite and catalysis. Initially a brief overview of the slate industry, past and present, is provided to illustrate the relevance of this study to the slate industry of North Wales. An overview of previous work on the origin, formation and composition of slate is provided in addition to a review of previous work on slate expansion. An overview of the thermal decomposition of pyrite, a common accessory mineral in slate, is also discussed. This section mainly focuses on the work previously carried out on the decay of FeS2 in oxidising, reducing and inert atmospheres when present in host materials such as coal or gold. Finally an overview of catalyst support materials, hydrogenation
catalysts and techniques in catalyst preparation is provided.
Chapter Two, Slate, provides details on the characterisation work carried out on slate from the Llechwedd Slate Quarry, North Wales. Studies have also been undertaken on slate from the Villar de! Rey Slate Quarry, Spain. The thermal chemistry of slate is discussed focussing on determining the mechanism behind slate expansion. The investigation undertaken to identify the nature of the expansion gas and the key factors in expansion control i.e. heating rate, dwell times and final temperature is discussed.
Chapter Three, Pyrite, investigates the thermal decomposition of pyrite, pyrite in Welsh slate and pyrite in Spanish slate. Experiments have been carried out in nitrogen and in air to provide a mechanistic study of pyrite decay under different atmospheric conditions. A detailed study by SEM of the morphological changes occurring in pyrite after heating is given illustrating the differences in the decay mechanism of pyrite in the various atmospheres. An investigation to determine the differences in the decomposition of FeS2 within the internal matrix of slate compared to pyrite on its own is also provided. The effect of slate as a host material on the decomposition of F eS2 is discussed.
Chapter Four, Catalysis, investigates the potential use of expanded slate as a support material for a catalytically active metal. Details on the preparation of copper and palladium supported metal expanded slate catalysts by following impregnation and electroless plating techniques is provided. The activity of the catalysts towards hydrogenation reactions involving nitrobenzene, maleic acid and cyclohexene is discussed.
Chapter Five, Experimental, provides details of the experimental work carried out and the instruments used in the course of this study to investigate the expansion phenomenon of slate, the thermal decomposition of pyrite and the catalytic properties of expanded slate based catalysts.