Thermal treatment of minerals has been researched over the past few decades, with a view to reducing the energy requirements in the comminution process. The use of microwave radiation has proven especially interesting, due to the differential dielectric heating leading to the generation of intergranular fractures, therefore better liberation of minerals and a reduction in the generation of fines, which are notoriously difficult to process. This thesis specifically investigated the effect of microwave pre-treatment on the efficiency of the downstream separation processes used in the minerals industry. If any energy savings that are made in the comminution process are negated by a severely detrimental effect in the separation of valuable mineral from the gangue then this would not make economic sense for microwave pre-treatment to be utilised. Conventional heat treatment, in air, lead to the formation of oxide mineral phases throughout the bulk of the pyrite, galena, ilmenite and molybdenite samples analysed. This heat treatment had no effect on the mineralogy of the chromite sample. Thermal alteration of the kaolinite sample tested also revealed no significant changes. Dielectric measurements of the minerals showed that all would adsorb microwave radiation, apart from chromite and kaolinite. Exposure to microwave radiation did not induce changes in the bulk mineral, as shown by X-ray diffraction analysis. However, use of scanning electron microscopy showed evidence of oxidation of the pyrite surface, and a mineral liberation analyser showed the formation of pyrrhotite and hematite on the surface of the particles.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:550864 |
| Date | January 2007 |
| Creators | Waters, Kristian Edmund |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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