Thesis (M.S.)--Oregon State University, 1963. / Typescript. Includes bibliographical references (leaves 75-81). Also available on the World Wide Web.

Thesis (PhD) -- University of South Australia, 1998

Thesis (Ph. D.)--Columbia University, 1933. / Vita. Bibliography: p. [56-58].

School of Chemical and Metallurgical Engineering, Faculty of Engineering and Built in Environment, University of Witwatersrand, Johannesburg, South AfricaMay, 2016 / Trojan Nickel Mine in Bindura, Zimbabwe, produces nickel concentrates which, until 2008, were then processed at their smelter operations (Bindura Smelter and Refinery) and the subsequent product sent to the hydrometallurgical plant to produce nickel cathodes. However, due to economic challenges the smelter and hydrometallurgical plant operations were closed down in 2008. Currently, Trojan Mine produces nickel concentrates through flotation which are then sold to Glencore International, in China, for further processing. Since 2002, the MgO (also known as talc) content in the Trojan Nickel Mine final concentrates has increased from around 12% to a peak of 22%. The average MgO content in the concentrates for the year ending in March 2015 was 16.14%. An offtake agreement of sale was made with Glencore International, in China, whereby a penalty is charged for all concentrates with MgO levels greater than 5%. In the year 2015 alone, monthly revenue due to smelter penalties amounted to an estimated total of US$141 000. Higher MgO levels in the concentrates are prevalent when processing low grade ores, with nickel content ranging from 0.65-1.2%. This research focused on reducing the MgO content of the Trojan’s final concentrate to 12%; which was the smelter’s set target while it was still operational. In order to investigate the effect of pH and chemical depressants on the MgO levels in the concentrate, batch flotation tests were carried out at pH 8.95 and 10.2, using several guargum depressants namely: Betamin DZT 245 (standard), Cytec S9349, DLM PDE, DLM RS, and CMC (carboxy methyl cellulose) depressants namely: Depramin 177, 267 and 347, and ND 521, 522 and 523. The concentrates were collected at 1, 5, 15 and 25 minute intervals in order to understand the stage-wise recovery of nickel and MgO minerals. A flotation test, without a depressant, was also carried out in order to understand the kinetics of the gangue minerals. Stage addition of depressants was investigated, by adding another 50g/t dose of the DZT 245 depressant after 1 minute into the flotation test. Collector combination tests using SIPX, SIPX:NC228, SIPX:NC236 and SIPX:PNBX, were also carried out to determine the best reagent suite. To understand the recovery of nickel and MgO in the flotation circuit, a plant survey was carried out, and the particle size distribution (PSD) and assays of collected samples were determined. Flotation tests results indicated that DLM RS and DLM PDE guargum depressants had better selectivity towards MgO and higher nickel recoveries as compared to the Betamin DZT 245 depressant that is currently used in the plant. It is recommended that a plant trial be carried out using the DLM RS depressant, which further reduced the MgO and mass of concentrate recovered by 3.79% and 32% respectively. The stage recovery of MgO for a test carried out without a depressant showed that 57.7% of the MgO was recovered during the first five minutes of the test. Thus, there is need to effectively depress the fast floating MgO during the early stages of the flotation process. Nickel recovery and grade were increased by 2.7% and 2.1% respectively, after adding the second dose of the depressant after 1 minute into the flotation test. The results indicated that the fast floating MgO can depress the valuable mineral if the depressing effect of the depressant is short-lived, which in turn leads to reduced nickel recoveries. Hence, reducing the time between the two stage additions of the depressant in the plant will help further supress the fast floating MgO silicates. It was also noted that at least 60% of the nickel was recovered during the first five minutes of the tests. Hence, reducing the residence time of the rougher flotation bank would reduce MgO recovery into the concentrates without adversely affecting the nickel recoveries. Plant survey results showed that the scavenger bank feed that was deslimed, had less finer MgO particles and MgO content as compared to the rougher bank feed. This indicates that desliming before the coarse flotation process could reduce MgO slimes in the feed, reduce the recovery of MgO due to slime coatings in the final concentrates and the reagent consumption in the bank. Introducing the desliming unit could be beneficial since the desliming cyclones have low installation and operational costs. / MT2016

Thesis (Ph.D.)--Murdoch University, 2005. / CD-ROM contains appendix G. Thesis submitted to the Division of Science and Engineering. Bibliography: leaves 205-218.

Thesis--University of Missouri, School of Mines and Metallurgy, 1876. / The entire thesis text is included in file. Holograph [Handwritten and illustrated in entirety by author]. Title from title screen of thesis/dissertation PDF file (viewed September 5, 2008)

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This research study is more of an initiative towards Social Impact Assessment of copper-nickel mining in Botswana. The specific objectives of the study were centred on the assessment of the social impacts of copper-nickel mining in Botswana from the initial mining stage of exploration, surveying and mine site development to mine closure. The study was carried out under the broad hypotheses that mining influences population movement that impact on areas of mining; mining activities have both economic benefits and deleterious social impacts on the local communities found in the areas where mining is taking place; and mine closure has far reaching socio-economic, investment and developmental implications over and above the obvious interests of project owners. To achieve the broad aim as summarised above, the research study used a multi-disciplinary methodology and approach that required several kinds of expertise and sources of information. Hence it used both primary and secondary sources centred on interactive informative interviews, site visits and observations, questionnaires, census data records, mining companies’ publications, published textbooks and journal articles. The research study comprised of three different mines operated by three different mining companies in three varied socio-cultural and ethnic regions of Botswana. First was a detailed Social Impact Assessment of the initial phase of exploration, surveying and mine site development represented by Mowana mine project operated by African Copper in the rural areas of Dugwi and Mosetse. This case study yielded results showing that the social impacts of mining in the area are diverse and extensive. The findings suggest that the impacts relate not only to the possible economic benefits of foreign exchange, employment, the optimal use of available mineral resources and the possible development of Dugwi and Mosetse villages, but extends to the deleterious social impacts. The results also indicated that the social impacts have just begun in the two communities. Hence they point towards a possible disruption within the socio-cultural system of the local people if serious mitigation measures are not put in place; thus suggesting that the early stages of exploration and mine site development results in the most conflict between the mine and the local people. Second was a comprehensive Social Impact Assessment of Tati-Nickel Phoenix mining project in the peri-urban areas of Matshelagabedi and Matsiloje areas representing the mining stage of mine production and expansion. The results from this case study suggest that during vi mine production and expansion, many people were relocated. However, the overriding impression gained from the case study was Tati-Nickel Mining Company’s elaborate corporate policies that suggested good corporate governance and best practices that promote sustainable development. A notable milestone on good corporate governance and best practice that the other two case studies (mining company) could benchmark on is Tati-Nickel’s corporate social responsibility programme that has been designed to ensure that the communities within a fifty kilometre mine radius benefit from the mine. The results from the case study also distinguished the mining stage of production and expansion from the other two because it is associated with the deep entrenchment of the social impacts into the communities near to mining areas. Third was a detailed Social Impact Assessment on Bamangwato Concession Limited mine in the industrial town of Selebi-Phikwe. The case study represented the stage of mine closure. Through the findings of this case study, it became apparent that the economic dependence of Selebi-Phikwe on mining has seen the town developing into a mining town, increasing its vulnerability at mine closure. The results from the case study further suggest that mine closure will degrade the socio-economic sector of the town with ever far reaching socio-economic implications as many people lose their gainful employment, hence suggesting that a possible complete mine closure will be the most traumatic phase leading to major social conflict within the area. Thus the results suggest that at mine closure, the deleterious social impacts will overspill to other areas in Botswana with disastrous effects for the economy of the country. The results yielded through this study established in clear and passionate language that copper-nickel mining in Botswana influences population movements that lead to positive and negative impacts on the communities found in mining areas. Another major finding of the study is that copper-nickel mining activities have both economic benefits and deleterious social impacts on the local communities, hence the recommendation that the copper-nickel mining companies should embrace the concept of sustainable mining for sustainable development to avoid most of the negative impacts of their operations on the local communities.

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