Browsing by Subject "Sphalerite"

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    Leaching of a zinc ore and concentrate  using the Geocoat™ technology
    (Elsevier, 2011) Soleimani, Mohammad; Petersen, Jochen; Roostaazad, Reza; Hosseini, Soheil; Mohammad, Mousavi; Najafi, Alireza; Vasiri, Akhtarolmolouk Kazemi
    In this study, the Geocoat™ technology was used for the extraction of zinc from a mineral concentrate obtained from the Kooshk mine (Yazd, Iran) by a culture dominated by the mesophilic bacterium Acidithiobacillusferrooxidans in a packed column bioreactor. A low grade sphalerite ore was used as support for the concentrate coating. During the 100 days of leaching pH, Fe3+, Fetotal, microbial population density and zinc extraction were measured. The final zinc extraction from concentrate and low grade support was 97% and 78%, respectively, and it was found that leaching from the support does not proceed significantly before leaching from the coating is completed.
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    Modelling zinc heap bioleaching
    (Elsevier, 2007) Petersen, J; Dixon, D G
    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 results. The model calibration thus confirmed, a detailed sensitivity study was conducted in order to establish the key parameters that determine the overall rate of Zn extraction. In the present case these were found to be oxygen gas–liquid mass transfer, various factors affecting the delivery of acid into the heap, and factors affecting the temperature distribution within the heap. A set of improved design parameters are proposed that would almost double the zinc conversion rate measured in the pilot plant – from 83% in 740 days to 78% in 383 days – and increase zinc production rate from 1.77 to 4.35 kg/m2/day. However, this improvement must be evaluated in the context of various implications for the downstream process.
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    Use of X-ray computed tomography to investigate crack distribution and mineral dissemination in sphalerite ore particles
    (Elsevier, 2011) Ghorbani, Yousef; Becker, Megan; Petersen, Jochen; Morar, Sameer H; Mainza, Aubrey; Franzidis, J-P
    As the trends in mineral processing move towards the beneficiation of finer grained and more complex ore bodies, so too do the methods needed to understand and model these processes. During the heap leaching of low-grade ore bodies, the crack distribution and mineral dissemination in ore particles are important characteristics that determine the performance of sub-processes, such as the diffusion of reagents in and out of particle pores. Recent developments in X-ray computed tomography (CT) as an advanced diagnostic and nondestructive technique have indicated the potential for the technology to become a tool for the acquisition of 3-D mineralogical and structural data. The spatial distribution of cracks and mineral dissemination in particles derived from a sphalerite ore in the Northern Cape, South Africa, was characterized using a high-resolution industrial X-ray CT system. This paper describes the use of image analysis techniques including image segmentation, which uses a combination of thresholding and other methods to characterize and quantify crack and mineral dissemination in the sphalerite particles. The results are validated with those obtained using traditional techniques such as physical gas (with N2) adsorption, mercury intrusion porosimetry, SEM and QEMSCAN. A comparison of the effect of different comminution devices (HPGR and Cone crusher) on crack generation is also given.