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Abstract

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Abstract: A common problem faced during the recovery of valuable metals is the presence of impurities/unwanted elements. In order to retain a high concentration of a desired metal, all impurities which affect the metal’s recovery should be removed before the final stage of recovery. In this work, research is conducted on the removal of residual sulphur from refractory gold bearing bioleach residue through the application of bio-oxidation, where sulphur is oxidized at different temperatures and pH levels to form sulphuric acid. Refractory sulphide ores and concentrates often consume large quantities of cyanide during leaching of gold using cyanide solution. Sulphides, elemental sulphur and many base metals react readily with cyanide, reducing the amount of cyanide available for leaching of the desired metal. So sulphur causes problems by increasing cyanide consumption and decreasing the environmental quality of the residue. In this research bacterial oxidation of sulphur was simulated in volumetric and Erlenmeyer flasks where inoculums were added to sulphur suspension to catalyse the oxidation of sulphur. Some of the flasks were operated at different pH levels and were controlled using a NaOH solution to investigate the optimum conditions of bacterial oxidation of sulphur. The controlled pH of 2.6 and a temperature of 50oC were found to be the best conditions for bacterial oxidation of sulphur. So this problem of sulphur consuming cyanide could possibly be overcome by controlling the pH at 2.6 and temperature at 50oC in the final stage of bacterial leaching gold plant using NaOH or some other neutralizing agent depending on the cost, which happens to enhance the kinetics of bacterial oxidation of sulphur. The operational conditions of moderate temperature and atmospheric pressure make this method very attractive from economic and environmental point of view.

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Abstract: An integrated procedure for steam extraction followed by volatiles sampling and analysis from the leaves of the Eucalyptus tree was explored. There are two problems to overcome in the extraction from solid plant materials: that of releasing the essential oils from solid matrix and letting it diffuse out successfully, and to model in a manner that can be scaled-up to industrial proportions. Towards this end, the effect of different parameters, such as temperature, pressure and extraction time on the extraction yield were investigated. Temperature (90oC, 97oC, and 99oC) was found to be a significant parameter affecting yield. An increase in yield was observed as pressure was increased and the use of high pressure (150 kPa) in steam generation units permits much more rapid and complete distillation of essential oils over atmospheric pressure. The yield was calculated from the relation between the essential oil mass extracted and the raw material mass used in the extraction. The volatiles, Eucalyptus oil in vapour form, released from the leaves were condensed and analyzed using Gas Chromatography, and eight major components were found to be contained in this species. A mathematical model based on diffusion of essential oil in the leaves was developed. Using a numerical method, the best diffusion coefficient was established for different operating conditions by comparing the model concentration of oil remaining in the leaves with the experimental amount of oil recovered; hence minimizing the sum of squared errors. It was found that one can not simply assume that the oil leached and recovered at the end of a run was the same as that originally present in the leaves. The initial mass of oil was determined by fitting the diffusion model to the data at all temperatures. The Arrhenius model was used to account for the effect of temperature. The resulting expression for the diffusion coefficient as a function of temperature can now be used to model the large scale extraction of the essential oils from Eucalyptus leaves.

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Abstract: Long range imaging systems that capture video through the atmosphere face a major problem in the form of atmospheric turbulence. This turbulence causes a phenomenon called heat shimmer which appears as a blurring and a wavering geometric distortion of the target scene which limits the effective range of the imaging system. We explore an image processing approach to mitigating the blurring effect of this distortion by using a blind deconvolution technique to sharpen the video signal and a dynamic illuminance-reflectance correction technique to improve the signal’s contrast. The algorithm is implemented on a Graphics Processing Unit to achieve near real-time performance.

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Abstract: Metal sulphate containing acid mine water decantation is generally expected to be an ever increasing challenge as mining activity winds down on the Witwatersrand. The water is contaminated due to by-products of aerobic bacterial action, which catalyses the oxidation of sulphide minerals in the presence of oxygen and water. During the flooding of an abandoned mine, air is replaced with ground water, limiting the access of oxygen as this gas is only sparingly soluble in water. This paper is a theoretical study on how the quality of decanting mine water at a given location may be expected to vary in the longer term.

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Abstract: Mining disturbs geologic formations that took millions of years to form; once disruption has taken place, a variety of problems may arise, from physical hazards to pollution of water and soil. The main goal of this paper is to demonstrate the technical feasibility of ferric and ferrous ions in-situ removal from Acid Mine Drainage and to design suitable flowcharts that can be used to model in-situ neutralization. The principle is based on lime neutralization without agitation that consists of diffusion and neutralization of hydrogen ions within the solution, which will increase the pH and lead to diffusion and precipitation of ferric and ferrous ions. Experimental tests were conducted with raw Acid Mine Drainage solution from Randfontein Mine (Johannesburg, South Africa) and the method shows that it is possible to achieve about 90 - 98% efficiency for ferric and ferrous ions in-situ removal from Acid Mine Drainage.

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Abstract: Please refer to full text for abstract

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Abstract: Static power converters produce harmonics due to the nature of the conversion process. This paper will investigate the effect on the power factor of a sinusoidal and Fryze current reference on a PWM boost type rectifier. It has been shown in previous papers that a Fryze current ref is best. This paper will develop a mathematical model, based on the single sided Fourier expansion. Using this mathematical model it will be shown that even though a high harmonic content could be present in a Fryze controlled PWM boost type rectifier, the power factor has been optimally improved.

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Aricle

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Artcle

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article

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Article

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Article.

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Article:Global Engineering Education Conference (EDUCON)

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Articles

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Artilce

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Artilcle

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Artiucle

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Book

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Book chapter

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Book Chapter

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Book Discussion

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Challenges affecting leadership development in the construction industry

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Citation: Joseph, Meera K. & Varachiam, Farouk. 2016. Technology transfer through industry-University-government collaboration.

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Citation: Nemes, C. & Tshibanda, M. 2012. Stochastic analysis for wind speed forecasting. The International Conference on Innovation and Collaboration in Engineering Research (INCER), 2-4 July, 2012, Bucharest, Romania.

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Citation: Nicolae,D.V., Richards, C.G. & Ehlers, P. 2010. Small power, three to one phase matrix converter for wind generators.International Symposium On Power Electronics, Electrical Drives, Automation And Motion (SPEEDAM), June 14-16, 2010, Italy:1339-1343. DOI:10.1109/SPEEDAM.2010.5542159

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Citation: Pan, X. 2013. System Integration of Automated Mine Optimization System. International Symposium Control, Optimization and Automation in Mining, Minerals and Metal Processing, 25-28 August, 2013, San Diego, California.

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Citation: Sun, Y. et al. 2014. Hypothesis testing-based adaptive PSO. Journal of Engineering, Design and Technology 12(1):89-101.

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Citation: Sun, Y., Wang, Z., Van Wyk, B.J. 2013. Chaotic hopfield neural network swarm optimization and its application. Journal of applied mathematics, 2013,(10)

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Conference

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Conference Paper

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Conference paper

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Conference preceeding

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Conference preceedings

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Conference procedings

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Conference proceeding

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Conference proceedings

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Conference Proceedings

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Conference proceedings.

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Conferende proceedings

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Dataset

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Discusion

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Discussion

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Doctoral (Thesis

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Doctoral (Thesis)

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Doctoral Thesis

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Doctoral(Thesis)

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English

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Exam

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Exam paper

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Finding Aid

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Formula sheet

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games

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gamification

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Image

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images

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Inaugural

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Journal

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Journal Article

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Journal article

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M.Com Thesis

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M.Ed. Thesis

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M.Phil. (Engineering Management)

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M.Tech. (Construction Management)

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M.Tech. (Operations Management)

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Magazine

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Master (Thesis)

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Masters

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Masters (Thesis

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Masters (Thesis)

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Masters (Thesis0

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Masters Thesis

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Masters TThesis)

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Masters(Thesis)

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Master’s Thesis

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Mini-Dissertation

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Musical Score

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Newsletter

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Other

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Presentation

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Proceedings conference

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Public lecture

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Recording, oral

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Report

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Seminars

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Software

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Technical Report

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Thesis

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Thesis (D. Phil)

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Thesis (D. Phil.)

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Thesis (D.Cur)

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Thesis (Doctorate)

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