OpenUCT Home
→
Browsing by Author

Browsing by Author "Petersen, J"

Now showing items 1-18 of 18

Ageing of chromium(III)-bearing slag and its relation to the atmospheric oxidation of solid chromium(III)-oxide in the presence of calcium oxide

Author: Pillay, K ; von Blottnitz, H B ; Petersen, J Date: 2003 Slag arising in ferrochromium and stainless steel production is known to contain residual levels of trivalent chromium. As the chromium is normally bound in the slag matrix in various silicate or spinel phases, and hence not easily mobilised, ... Read more c b n d
An agglomerate scale model for the heap bioleaching of chalcocite

Author: Ogbonna, N ; Petersen, J ; Laurie, H D G Date: 2006 A mathematical model for bioleaching at the agglomerate scale is developed. The agglomerate is defined as a unit volume of a heap which contains a solid phase (a size distribution of ore particles), a liquid phase (stagnant and flowing leaching ... Read more
An Annual and Seasonal Characterisation of Winery Effluent in South Africa

Author: Sheridan, C M ; Glasser, D ; Hildebrandt, D ; Petersen, J ; Rohwer, J Date: 2011 Winery effluent is known to have a high chemical oxygen demand (COD) and a low pH. In this study, we extensively analysed effluent from two cellars and studied the temporal changes over the duration of a harvest and the duration of a year. ... Read more
An annual and seasonal characterisation of winery effluent in South Africa

Author: Sheridan, C M ; Hildebrandt, D ; Glasser, D ; Petersen, J ; Rohwer, J Date: 2011 Winery effluent is known to have a high chemical oxygen demand (COD) and a low pH. In this study, we extensively analysed effluent from two cellars and studied the temporal changes over the duration of a harvest and the duration of a year. ... Read more
Biooxidation kinetics of Leptospirillum ferriphilum under heap bioleach conditions

Author: Ojumu, T V ; Harrison, S T L ; Hansford, G S ; Petersen, J Date: 2008 Although the kinetics of biological oxidation of ferrous to ferric iron–the key step in any bioleaching process–have been studied for a variety of organisms, the focus has always been on conditions typical of tank-bioleaching. In heaps, ... Read more
Carbon dioxide and oxygen consumption during the bioleachingof a copper ore in a large isothermal column

Author: Petersen, J ; Minaar, S H ; du Plessis, C A Date: 2010 During large-scale column tests at BHP Billiton's Johannesburg Technology Centre (JTC) on a low-grade copper ore during 2005/6, the concentrations of both oxygen and CO2 were continuously monitored in feed and exit gas as well as at various ... Read more
Determination of oxygen gas-liquid mass transfer rates in heap bioleach reactors

Author: Petersen, J Date: 2010 A detailed experimental study is described which was conducted to determine the rate of oxygen gas–liquid mass transfer within the packed bed of heap bioleach reactors at different temperatures (22–68 °C), using the Na2SO3 method. The raw ... Read more
The influence of applied potentials and temperature on the electrochemical response of Chalcopyrite in Bacterial Leaching

Author: Tshilombo, A F ; Petersen, J ; Dixon, D G Date: 2002 Electrochemical techniques were conducted to clarify the role of solution potential and temperature under a variety of experimental conditions similar to those found during the mesophilic and thermophilic biooxidation of chalcopyrite (CuFeS2). ... Read more c b n d
Investigation of particles with high crack density produced by HPGR and its effect on the redistribution of the particle size fraction in heaps

Author: Ghorbani, Yousef ; Petersen, J ; Becker, Megan ; Mainza, Aubrey Njema ; Franzidis, Jean-Paul ; Kalala, JT Date: 2013 The application of comminution technology such as the High-pressure grinding rolls (HPGR), which is able to generate a high density of cracks in the ore particles, is favourable for leaching processes. Extraction of metallic values by the ... Read more c b
Investigation of the effect of mineralogy as rate-limiting factors in large particle leaching

Author: Ghorbani, Yousef ; Becker, Megan ; Petersen, J ; Franzidis, Jean-Paul Date: Oct 2013 Although heap leaching is by now well established in the mining industry, the process remains limited by low recoveries with different rate-limiting factors that are not clearly understood. In this study, three large particle size classes ... Read more c b
The kinetics of ferrous-iron oxidation by Leptospirillum ferriphilum in continuous culture: the effect of pH

Author: Ojumu, T V ; Petersen, J Date: 2011 The kinetics of ferrous ion oxidation by Leptospirillum ferriphilum were studied in continuous culture with a focus on the effect of solution pH (pH 0.8–2.0), assuming that the effect of pH on cell metabolism can be independently studied of ... Read more
The kinetics of ferrous-iron oxidation by Leptospirillum ferriphilum in continuous culture: the effect of temperature

Author: Ojumu, T V ; Hansford, G S ; Petersen, J Date: 2009 A typical bioleach heap is characterized by wide variation of temperature across the heap bed, leading to oxidation of target minerals occurring at different rates. Previous studies on the effect of temperature on the microbial oxidation of ... Read more
Microbial leaching of a low-grade sphalerite ore using a draft tube fluidized bed bioreactor

Author: Soleimani, M ; Hosseini, S ; Roostaazad, R ; Petersen, J ; Mousavi, S M ; Vasiri, Kazemi A Date: 2009 The use of a draft tube fluidized bed bioreactor (DTFBB) has been successfully demonstrated for the bioleaching of a chalcopyrite concentrate (Mousavi, et. al., 2005). In the present paper this technique was used for the bioleaching of zinc ... Read more
Modelling and Assessment of the Long-term Leachate Generation Potential in Deposits of Ferro-chromium Slags

Author: Petersen, J ; Petrie, J G Date: 2000 The environmental impact of solid waste materials is closely linked to their potential to produce a hazardous leachate once deposited in a landfill. This potential is conventionally assessed with simple laboratory batch leach tests, which ... Read more c b
Modelling of bioleach processes: connection between science and engineering

Author: Petersen, J Date: 2010 This paper gives a brief introduction to the modelling of bioleach processes, developed from a careful analysis of the fundamental process steps at the gas–liquid, biological and mineral interfaces, and how these interact in a given reactor ... Read more
Modelling zinc heap bioleaching

Author: Petersen, J ; Dixon, D G Date: 2007 A comprehensive modelling study of the HydroZinc™ heap bioleach process, using the HeapSim modelling tool, is described. The model was calibrated on the basis of a small number of column leach experiments and compared against pilot heap test ... Read more
A review of rate equations proposed for microbial ferrous-iron oxidation with a view to application to heap bioleaching

Author: Ojumu, T V ; Petersen, J ; Searby, G E ; Hansford, G S Date: 2006 In view of the fact that the microbial oxidation of ferrous iron to the ferric form is an essential sub-process in the bioleaching of sulphide minerals, the development of a comprehensive rate equation for this sub-process is critical. Such ... Read more
Thermophilic Heap Leaching of a Chalcopyrite Concentrate

Author: Petersen, J ; Dixon, D G Date: 2002 Thermophiles have been shown to be the only micro-organisms to leach chalcopyrite successfully. Heap leaching may be a feasible alternative to conventional bio-reactors, providing a high temperature environment can be maintained within the ... Read more c b n d