Browsing by Author "Broadhurst, J L"

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    A comparison of pyrrhotite rejection and passivation in two nickel ores
    (Elsevier, 2013) Chimbganda, T; Becker, M; Broadhurst, J L; Harrison, S T L; Franzidis, J.-P
    The non-stoichiometric sulfide mineral pyrrhotite (Fe1-xS) occurs almost ubiquitously inter-grown with the principal nickel mineral, pentlandite ((Fe,Ni)9S8). During Ni processing, pyrrhotite is generally rejected to the tailings stream by flotation to produce a low tonnage, high grade (Ni) smelter feed and reduce SO2 emissions. In this study, the effect of different pyrrhotite flotation rejection strategies (artificial oxidation and TETA: SMBS addition) are evaluated on a magnetic (Ore A) and non-magnetic (Ore B) pyrrhotite ore to determine if either may effectively depress and potentially passivate the pyrrhotite surface during flotation to produce benign tailings without compromising pentlandite recovery. For both ores, the best pyrrhotite rejection (pentlandite/pyrrhotite recovery) was obtained using TETA: SMBS. Differences in the flotation performance of the two ores are considered more a function of BMS content, liberation and ore handling rather than a difference in sulfide passivation from the inherent pyrrhotite mineralogy (magnetic vs non-magnetic pyrrhotite). Pyrrhotite passivation could possibly provide a means of rendering the tailings non-reactive and thus mitigate acid rock drainage (ARD) formation.
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    A comparison of pyrrhotite rejection;passivation in two nickel ores
    (Elsevier, 2013) Chimbganda, T; Becker, M; Broadhurst, J L; Harrison, S T L; Franzidis, J-P
    The non-stoichiometric sulfide mineral pyrrhotite (Fe1-xS) occurs almost ubiquitously inter-grown with the principal nickel mineral, pentlandite ((Fe,Ni)9S8). During Ni processing, pyrrhotite is generally rejected to the tailings stream by flotation to produce a low tonnage, high grade (Ni) smelter feed and reduce SO2 emissions. In this study, the effect of different pyrrhotite flotation rejection strategies (artificial oxidation and TETA: SMBS addition) are evaluated on a magnetic (Ore A) and non-magnetic (Ore B) pyrrhotite ore to determine if either may effectively depress and potentially passivate the pyrrhotite surface during flotation to produce benign tailings without compromising pentlandite recovery. For both ores, the best pyrrhotite rejection (pentlandite/pyrrhotite recovery) was obtained using TETA: SMBS. Differences in the flotation performance of the two ores are considered more a function of BMS content, liberation and ore handling rather than a difference in sulfide passivation from the inherent pyrrhotite mineralogy (magnetic vs non-magnetic pyrrhotite). Pyrrhotite passivation could possibly provide a means of rendering the tailings non-reactive and thus mitigate acid rock drainage (ARD) formation.
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    A mineralogical approach to evaluating laboratory scale acid rock drainage characterisation tests
    (Elsevier, 2015) Becker, M; Dyantyi, N; Broadhurst, J L; Harrison, S T L; Franzidis, J-P
    Effective management of the risks associated with acid rock drainage (ARD) requires the ability to identify material with a potential to generate ARD reliably. With the increasing prevalence of quantitative mineralogy (Quantitative XRD, auto-SEM), opportunity exists to use mineralogy at all stages in ARD characterisation and prediction. This study uses a mineralogical approach across the head grade samples and the residues obtained under leach conditions of several common ARD characterisation tests (Acid Neutralising Capacity, Net Acid Generation), as well as the University of Cape Town (UCT) biokinetic test to evaluate the extent to which acid-neutralising minerals react. The results show the contribution of the carbonates to the acid neutralising capacity, as well as the partial dissolution of intermediate weathering silicate minerals such as chlorite and mica.
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    Mitigating the generation of acid mine drainage from copper sulphide tailings impoundments in perpetuity: A case study for an integrated management strategy
    (Elsevier, 2010) Hesketh, A H; Broadhurst, J L; Harrison, S T L
    Acid mine drainage (AMD) is one of the most serious and pervasive challenges facing the minerals industry. Current philosophy in sulfide tailings management takes an end-of-pipe approach which is yet to be shown to be sufficient to prevent post-closure impacts from AMD and guarantee “walk-away” status. An improved, integrated approach to tailings management and AMD mitigation is proposed, whereby conventional tailings are separated with the use of flotation into a largely benign tailings stream and a sulfide-rich product. The key features of this conceptual approach are outlined and partly demonstrated for the case of porphyry-type copper sulfide tailings. The significance of this approach is that it provides a basis for the identification of opportunities for the development of new process designs incorporating waste management systems for mitigating AMD in a manner consistent with the principles of cleaner production and sustainable development.