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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Exploring conditions leading to self-heating of pyrrhotite-rich materials

Wang, Xinran, 1973- January 2007 (has links)
Self-heating of sulphide minerals has a potential for serious impact on environment and safety in mining of ores, and storage and transport of concentrates. A research program, focused on the investigation of the conditions under which the H2S is produced from pyrrhotite-rich materials, has been initiated using the self-heating facility and technology developed at the Noranda Technology Centre. It is hypothesized that H 2S production could be important in self-heating as the exothermic heat of oxidation of H2S to SO2 is greater than that for oxidation of S to SO2. / The hypothesis of liberation of H2S was tested using copper (as metal pieces and sulphate solution) as a detector, both in the self-heating apparatus and in a "weathering" apparatus at 40°C. X-ray diffraction and scanning electron microscopy analysis of coatings and precipitates confirmed the formation of copper sulphide and therefore indicated the release of H 2S. Release of H2S involves acid conditions and the possible origin of the acidity was discussed. / Prior work had suggested that the level of exposure to oxygen was a factor in self-heating. Tests were conducted to explore the role of oxygen level. Three tests were conducted in the weathering apparatus at 40°C with covers of no hole, 3 holes and 128 holes to control access the air. Weight gain was recorded every two days and stage B self-heating tests were conducted on the samples after a month of weathering. Under limited air access (no hole and 3 hole covers), the samples showed higher weight gain, higher degree of oxidation (by colour change) and higher self-heating rates compared with the sample with more exposure to air (128 hole cover). X-ray diffraction analysis identified the oxidation products elemental sulphur, maghemite and goethite in the samples under the limited air conditions. A series of non-standard self-heating tests were conducted in the self-heating apparatus under different air flow rates of Stage A. These showed that the samples weathered under low air flow rates yielded significantly higher self-heating rates in both stage A and B. / All the experiments indicate that a high level of exposure to air dose not promote self-heating but rather suppress it. Less oxidative conditions play a critical role in the self-heating of pyrrhotite-rich materials.
2

Exploring conditions leading to self-heating of pyrrhotite-rich materials

Wang, Xinran, 1973- January 2007 (has links)
No description available.

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