Effect of oxygen and micro-cracking on the flotation of low grade nickel sulphide ore
- Authors: Muzenda, Edison , Afolabi, Ayo S.
- Date: 2010
- Subjects: Flotation , Micro-cracking , Nickel sulphide ore , Oxygen
- Type: Article
- Identifier: uj:4712 , http://hdl.handle.net/10210/10958
- Description: This study investigated the effect of oxygen and micro-cracking on the flotation of low grade nickel sulphide ore. The ore treated contained serpentine minerals which have a history of being difficult to process efficiently. The use of oxygen as a bubbling gas has been noted to be effective because it increases the pulp potential. The desired effect of micro cracking the ore is that the nickel sulphide minerals will become activated and this activation will render these minerals more susceptible to react with potassium amyl xanthate collectors, resulting in a higher recovery of nickel and hinder the recovery of other undesired minerals contained in the ore. Higher nickel recoveries were obtained when pure oxygen was used as a bubbling gas rather than the conventional air. Microwave cracking favored the recovery of nickel.
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Effect of pH on the recovery and grade of base metal sulphides (PGMs) by flotation
- Authors: Muzenda, Edison , Afolabi, Ayo S. , Abdulkareem, Ambali S. , Ntuli, Freeman
- Date: 2011
- Subjects: Platinum Group Metals , Metal sulphides , Flotation
- Type: Article
- Identifier: uj:4713 , ISSN 2078-0966 , http://hdl.handle.net/10210/10959
- Description: This study investigated the effect of pH on the recovery and grade of the Platinum Group Metals (PGMs) and base metal sulphides from the UG2 ore of the Bushveld Complex. This was achieved through running a series of test work in a Denver flotation cell at varying pH 6-11 at constant reagent dosage. The UG-2 reef is characterized by two predominant gangue phases i.e. chromite and silicate, that have significantly different physical and chemical properties. The test work was aimed at evaluating which pH gives best recoveries, and finding the effect of the chrome content in these recoveries. A pH of 9 gave the highest recovery compared to other pH ranges. However, the highest PGM grade was attained at a pH of 6 which is slightly acidic. Ideally this trend could be expected since the collectors (xanthates) are more stable in alkaline medium. The higher PGM recovery was also accompanied by higher chrome content as a result of their similar chemical properties.
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Effect of temperature on specific retention volumes of selected volatile organic compounds using the gas-liquid chromatographic technique revisited
- Authors: Muzenda, Edison , Afolabi, Ayo S.
- Date: 2010
- Subjects: Specific retention volumes , Volatile organic compounds , Polydimethylsiloxane , Gas liquid chromatography
- Type: Article
- Identifier: uj:4711 , http://hdl.handle.net/10210/10957
- Description: This paper is a continuation of our interest in the influence of temperature on specific retention volumes and the resulting infinite dilution activity coefficients. This has a direct effect in the design of absorption and stripping columns for the abatement of volatile organic compounds. The interaction of 13 volatile organic compounds (VOCs) with polydimethylsiloxane (PDMS) at varying temperatures was studied by gas liquid chromatography (GLC). Infinite dilution activity coefficients and specific retention volumes obtained in this study were found to be in agreement with those obtained from static headspace and group contribution methods by the authors as well as literature values for similar systems. Temperature variation also allows for transport calculations for different seasons. The results of this work confirm that PDMS is well suited for the scrubbing of VOCs from waste gas streams.
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Estimating the absorption of volatile organic compounds in four biodiesels using the Unifac procedure
- Authors: Mateescu, Corina M. , Muzenda, Edison , Belaid, Mohamed , Abdulkareem, Saka , Afolabi, Ayo S.
- Date: 2011
- Subjects: Biodiesel , Volatile organic compounds , Absorption
- Type: Article
- Identifier: http://ujcontent.uj.ac.za8080/10210/363185 , uj:4696 , http://hdl.handle.net/10210/10760
- Description: This work considered the thermodynamic feasibility of scrubbing volatile organic compounds into biodiesel in view of designing a gas treatment process with this absorbent. A detailed vapour – liquid equilibrium investigation was performed using the original UNIFAC group contribution method. The four biodiesels studied in this work are methyl oleate, methyl palmitate, methyl linolenate and ethyl stearate. The original UNIFAC procedure was used to estimate the infinite dilution activity coefficients of 13 selected volatile organic compounds in the biodiesels. The calculations were done at the VOC mole fraction of 9.213x10-8. Ethyl stearate gave the most favourable phase equilibrium. A close agreement was found between the infinite dilution activity coefficient of toluene found in this work and those reported in literature. Thermodynamic models can efficiently be used to calculate vast amount of phase equilibrium behaviour using limited number of experimental data.
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Microstructure and mechanical properties of ultra-fine grained copper processed by equal channel angular pressing technique
- Authors: Sanusi, Kazeem O. , Afolabi, Ayo S. , Muzenda, Edison
- Date: 2014
- Subjects: Tensile properties , Equal channel angular pressing technique , Grain refinement , Ultra-fine grained copper
- Type: Article
- Identifier: uj:5005 , ISSN 2078-0966 , http://hdl.handle.net/10210/13145
- Description: The equal channel angular pressing (ECAP) technique is now recognised for achieving very significant grain refinement of ultra-fine grained materials which, at present produce unique mechanical properties. This study reports the results of the tensile tests and the microstructural analysis carried out on the specimens of ultra-fine grained (UFG) copper processed by ECAP technique at room temperature using a die with a 126o between the die channels. The copper samples used in this work were subjected to six and twelve passes during the ECAP processing. Tensile tests were conducted for samples cut out in two different directions; in the parallel and perpendicular direction at room temperature to evaluate the mechanical properties after the ECAP at these two directions. The microstructural characterization was carried out using optical electron microscope (OEM) and scanning electronic microscope (SEM). The results show ECAP technique introducing significant grain refinement and produced ultrafine grains in copper and there is a potential for achieving high ductility in the copper alloy after processing. The tested sample is characterized by significant differences of strength properties depending on the direction.
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Reagent optimization across a UG2 plant
- Authors: Muzenda, Edison , Abdulkareem, Ambali S. , Afolabi, Ayo S.
- Date: 2013
- Subjects: Reagent optimization
- Type: Article
- Identifier: uj:4860 , ISBN 978-988-19251-0-7 , http://hdl.handle.net/10210/12536
- Description: Reagent optimization is very important in the recovery of valuable metals from their ore via flotation. This is particularly important for large platinum operations where correct reagent regime and addition system can provide improvement opportunities in recovery and grade. Also reagent optimization can reduce reagent costs for the rougher, scavenger and cleaner flotation units. Reagents were optimized in the flotation of hot floats from the plant at laboratory scale. It was found that in order to save cost, the collector and depressant must be reduced in the roughers and cleaners respectively. This report presents results and some practical considerations that must be taken into account to optimise reagent usage.
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