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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--University of Missouri, School of Mines and Metallurgy, 1910. / The entire thesis text is included in file. Typescript. Walter I. Phillips determined to be Walter Irving Phillips from "Forty-First Annual Catalogue. School of Mines and Metallurgy, University of Missouri." Title from title screen of thesis/dissertation PDF file (viewed March 24, 2009) Includes bibliographical references (p. 12).

M.Phil. (Natural Economics) / Due to the overwhelming influence of gold on the national economy of South Africa, the importance of the other mineral resources are often underestimated. South Africa is the largest exporter of metals essential to the modern World industry - metals such as chrome, manganese and vanadium. Our vast reserves of these and other ferrous metals might yet prove to provide this country with substantial political and economic powers in years to come. The importance of the availability of ferrous metals for the continued existence of the modern global civilization is not always realised. These metals, in the form of various steels and other alloys, form an integral part of our daily lives in modern communities. This important role and the numerous problems faced by the global ferrous metals industry provided me with a challenging field of study. The phenomenon of cyclical volatility is inherent in mineral commodity markets and is eminently present in the markets for steel and related alloys, due mainly to the sensitivity of these markets to general economic welfare. In turn, and due to the derived demand relationship that exists between these metals and steel, the ferrous metals are particularly susceptible to economic prosperity and depression. More often than not, a period of economic prosperity is characterised by ferrous metal supply shortages, while excess supply is typical during periods of economic recession. Interest in the study of the complexities of ferrous metal markets was kindled whilst in the employ of the Minerals Bureau of the Department of Mineral and Energy Affairs.

En Nouvelle-Calédonie sont réalisées deux nouveaux projets métallurgiques. Tandis que le projet « usine du Nord » s’inscrit dans la politique de rééquilibrage, le projet Goro Nickel renforce à contrario la prééminence économique de la capitale Nouméa. Les résidents des tribus de Gatope, Oundjo, Baco et Netchaot, situées à proximité de la future usine du Nord, ont une perception grosso modo positive du projet. Ils voient dans la construction de l’usine non seulement un instrument politique pour l’émancipation de la population kanak, mais associent le projet surtout à l’espoir d’avoir un emploi. De l’autre côté, ils craignent les impacts sur l’environnement. Mais le terme « environnement » n’englobe pas uniquement l’environnement physique, mais également l’environnement culturel. Sur terre et en mer se trouvent des lieux sacrés qui ont une valeur d’identité. Outre un emploi direct chez l’opérateur minier, la création d’entreprise de sous-traitance et l’acquisition d’actions, la mise en valeur des terres coutumières représente un moyen de participation au projet du Nord. Parmi les quatre tribus étudiées, Baco remplit les meilleurs conditions requises pour une intégration de ses GDPL dans le développement de la zone VKP. Mais la mise en valeur d’une terre coutumière montre que des conflits entre clans resurgissent souvent concernant la question foncière. D’une part, le développement économique rapide entraîne l’apparition de nouvelles disparités sociales et pourrait accroître la marginalité des populations tribales kanak lorsqu’elles ne sont pas ou peu connectées à ce développement. D’autre part, les Kanak ont la possibilité de devenir des acteurs du développement. / Currently, two metal processing plants are built in New Caledonia. In contrast with the policy of territorial balance, supported by the Koniambo Project, the Goro Nickel Project will nurture the economic pre-eminence of the capital Nouméa. The inhabitants of the Kanak villages Gatope, Oundjo, Baco and Netchaot, located near by the future “factory of the north”, are generally speaking in favour of the nickel project. They not only regard the construction of the factory as a political instrument for the emancipation of the Kanakian population, but, above all, associate the project with the hope of a job. On the other hand, they fear negative impacts on the environment, especially concerning the lagoon and the mangrove forests. The term “environment”, however, does not only embrace the physical, but also the cultural environment. Identity-establishing holy sites are to be found ashore as well as in the sea. Alongside the opportunity to get a job at the nickel enterprise, the foundation of a supplier and the purchase of stocks, the valorisation of customary represents a chance to participate in the Koniambo Project. Baco is provided with the best premises to integrate its GDPLs into the economic process of the region VKP. But the valorisation of estates thus forms also displays the repeated conflict over the land issue among the clans. Whereas some Kanak make use of the economic development, others will likely suffer from such a marginalisation. / Im Neukaledonien entstehen zwei neue Metallverarbeitungsfabriken. Während das Koniambo-Projekt die Politik des räumlichen Ausgleichs unterstützt, wird das Goro-Nickel-Projekt die wirtschaftliche Vorrangstellung der Hauptstadt Nouméa fördern. Die Einwohner der Kanak-Dörfer Gatope, Oundjo, Baco und Netchaot, in der Nähe der zukünftigen „Fabrik des Nordens“ gelegen, haben eine im Großen und Ganzen positive Meinung von dem Nickelprojekt. Sie sehen im Bau der Fabrik nicht nur ein politisches Instrument für die Emanzipation der kanakischen Bevölkerung, sondern verbinden mit dem Projekt vor allem die Hoffnung auf einen Arbeitsplatz. Auf der anderen Seite fürchten sie negative Auswirkungen auf die Umwelt. Der Begriff „Umwelt“ steht jedoch nicht nur für die physische Umwelt, sondern auch für die kulturelle. Sowohl an Land als auch im Meer finden sich Heiligenstätten, die einen identitätsstiftenden Wert haben. Neben der Möglichkeit eines Arbeitsplatzes beim Nickelunternehmen, der Gründung eines Zuliefererunternehmens und dem Kauf von Aktien bildet die gewinnbringende Bewirtschaftung von Ländereien eine Chance zur Partizipation am Koniambo-Projekt. Von den vier untersuchten Kanak-Dörfern verfügt Baco über die besten Voraussetzungen zur Integration in die wirtschaftliche Entwicklung der Region VKP. Die gewinnbringende Bewirtschaftung von Ländereien zeigt aber auch, dass es immer wieder zu Streitigkeiten zwischen den Clans um die Landfrage kommt. Auf der einen Seite steht eine schnelle wirtschaftliche Entwicklung, auf der anderen Seite neue soziale Disparitäten, welche die Entwicklung nach sich zieht. Während einige Kanak die Entwicklung nutzen können, werden andere wahrscheinlich untere einer verstärkten Marginalisierung leiden.