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Chalcopyrite, galena, and sphalerite commonly coexist with pyrite in sulfidic waste rocks. The aim of this work was to investigate their impact, potentially by galvanic interaction, on pyrite oxidation and acid generation rates under simulated acid and metalliferous drainage conditions. Kinetic leach column experiments using single-minerals and pyrite with one or two of the other sulfide minerals were carried out at realistic sulfide contents (total sulfide 47% for galena vs <1.5% for chalcopyrite) over 72 weeks. The results are directly relevant to mine waste storage and confirm that the galvanic interaction plays a role in controlling acid generation in multisulfide waste even at low sulfide contents (several wt %) with small probabilities (≤0.23%) of direct contact between sulfide minerals in mixed sulfide experiments.
Gujie Qian; Rong Fan; Jianyin Huang; Allan Pring; Sarah L. Harmer; He Zhang; Maria Angelica D. Rea; Joël Brugger; Peter R. Teasdale; Christopher T. Gibson; Russell C. Schumann; Roger St. C. Smart; Andrea R. Gerson. Oxidative Dissolution of Sulfide Minerals in Single and Mixed Sulfide Systems under Simulated Acid and Metalliferous Drainage Conditions. Environmental Science & Technology 2021, 55, 2369 -2380.
AMA StyleGujie Qian, Rong Fan, Jianyin Huang, Allan Pring, Sarah L. Harmer, He Zhang, Maria Angelica D. Rea, Joël Brugger, Peter R. Teasdale, Christopher T. Gibson, Russell C. Schumann, Roger St. C. Smart, Andrea R. Gerson. Oxidative Dissolution of Sulfide Minerals in Single and Mixed Sulfide Systems under Simulated Acid and Metalliferous Drainage Conditions. Environmental Science & Technology. 2021; 55 (4):2369-2380.
Chicago/Turabian StyleGujie Qian; Rong Fan; Jianyin Huang; Allan Pring; Sarah L. Harmer; He Zhang; Maria Angelica D. Rea; Joël Brugger; Peter R. Teasdale; Christopher T. Gibson; Russell C. Schumann; Roger St. C. Smart; Andrea R. Gerson. 2021. "Oxidative Dissolution of Sulfide Minerals in Single and Mixed Sulfide Systems under Simulated Acid and Metalliferous Drainage Conditions." Environmental Science & Technology 55, no. 4: 2369-2380.
The aim of this study was to determine the reactivity of the chalcopyrite (112) surface under industrially relevant leaching conditions. Leaching of the chalcopyrite (112) surface was carried out at approximately pH 1 and in the presence of 0.01 M ferric or ferrous. The atomic force microscopy (AFM) and Raman microspectroscopy analyses suggested that the chalcopyrite (112) surface was relatively inert, with no formation of elemental sulfur observed over 42 days of leaching. In addition, it was found that the distribution of Fe-S and Cu-S bonds was always negatively correlated, as revealed by Raman analysis. This suggested that the breakage of the Fe-S and Cu-S bonds did not occur concurrently at a specific reaction site. The rate of variation of surface roughness, as reflected by AFM data, also suggested that leaching of the chalcopyrite (112) surface in the ferric or ferrous solution medium likely occurred more rapidly in the initial stage (fewer than seven days) than in the later stage (after seven days).
Gujie Qian; Christopher T. Gibson; Sarah Harmer-Bassell; Allan Pring. Atomic Force Microscopy and Raman Microspectroscopy Investigations of the Leaching of Chalcopyrite (112) Surface. Minerals 2020, 10, 485 .
AMA StyleGujie Qian, Christopher T. Gibson, Sarah Harmer-Bassell, Allan Pring. Atomic Force Microscopy and Raman Microspectroscopy Investigations of the Leaching of Chalcopyrite (112) Surface. Minerals. 2020; 10 (6):485.
Chicago/Turabian StyleGujie Qian; Christopher T. Gibson; Sarah Harmer-Bassell; Allan Pring. 2020. "Atomic Force Microscopy and Raman Microspectroscopy Investigations of the Leaching of Chalcopyrite (112) Surface." Minerals 10, no. 6: 485.
Yubiao Li; Yilun Yao; Bing Wang; Gujie Qian; Zhiming Li; Yangge Zhu. New insights into chalcopyrite leaching enhanced by mechanical activation. Hydrometallurgy 2019, 189, 1 .
AMA StyleYubiao Li, Yilun Yao, Bing Wang, Gujie Qian, Zhiming Li, Yangge Zhu. New insights into chalcopyrite leaching enhanced by mechanical activation. Hydrometallurgy. 2019; 189 ():1.
Chicago/Turabian StyleYubiao Li; Yilun Yao; Bing Wang; Gujie Qian; Zhiming Li; Yangge Zhu. 2019. "New insights into chalcopyrite leaching enhanced by mechanical activation." Hydrometallurgy 189, no. : 1.
The aim of this study was to determine the combined effect of galvanic interaction and silicate addition on the dissolution of pyrite, the major contributor to acid and metalliferous drainage (AMD). Single (pyrite, sphalerite, and galena)- and bi-sulfide (pyrite-sphalerite and pyrite-galena) batch dissolution experiments were carried out with addition of 0.8 mM dissolved silicate for comparison to previously published data. The pyrite dissolution rate was reduced by 98% upon silicate addition at pH 7.4 with little effect at pH 3.0 and 5.0. The effect of galvanic interaction on reducing pyrite dissolution decreased with increasing pH and was greater in the presence of sphalerite than galena. In contrast, the effect of silicate addition increased with increasing pH and was greater in the presence of galena than sphalerite. The greatest combined effect was at pH 7.4, with <0.1% of pyrite leached in both bi-sulfide systems. Silicate addition also significantly reduced the dissolution of sphalerite or galena (by 10-44%, except at pH 3 for the pyrite-sphalerite system). These results suggest that silicate addition, for reducing both pyrite dissolution and metalliferous drainage, may be applicable at a broad pH in mixed sulfide systems.
Gujie Qian; Rong Fan; Michael Short; Russell C. Schumann; Allan Pring; Andrea R. Gerson. The Combined Effects of Galvanic Interaction and Silicate Addition on the Oxidative Dissolution of Pyrite: Implications for Acid and Metalliferous Drainage Control. Environmental Science & Technology 2019, 53, 11922 -11931.
AMA StyleGujie Qian, Rong Fan, Michael Short, Russell C. Schumann, Allan Pring, Andrea R. Gerson. The Combined Effects of Galvanic Interaction and Silicate Addition on the Oxidative Dissolution of Pyrite: Implications for Acid and Metalliferous Drainage Control. Environmental Science & Technology. 2019; 53 (20):11922-11931.
Chicago/Turabian StyleGujie Qian; Rong Fan; Michael Short; Russell C. Schumann; Allan Pring; Andrea R. Gerson. 2019. "The Combined Effects of Galvanic Interaction and Silicate Addition on the Oxidative Dissolution of Pyrite: Implications for Acid and Metalliferous Drainage Control." Environmental Science & Technology 53, no. 20: 11922-11931.
In order to unravel the oxidation mechanism(s) of chalcopyrite (CuFeS2) surfaces, the surface anisotropy of CuFeS2 was investigated under both dry and aqueous atmospheres through a fundamental density functional theory (DFT) study. Results showed that the CuFeS2 (112) surface was the preferred cleavage surface, rather than the commonly-assumed (001) surface. Iron oxides were formed when contacting with either molecular O2 or dissociated O atoms, but sulfoxy species were only formed in the presence of dissociated O atoms, exposing Cu atoms on the S-terminated (001) and (112) surfaces. This indicates that strong oxidation conditions are beneficial to CuFeS2 oxidation and the release of metals into solution. In addition, CuFeS2 was preferentially oxidized by O2 prior to the adsorption of H2O under an aqueous condition with both H2O and O2. The H2O adsorbed on the O-oxidized surface further promoted CuFeS2 oxidation, resulting in the formation of a hydrophilic surface, rather than the naturally hydrophobic surface. This study has unveiled, for the first time, the mechanisms of the oxidation of the most stable and reactive CuFeS2 (112) and (001) surfaces under both dry and aqueous environments at an atomic level, with potential applications in CuFeS2 flotation and leaching processes.
Zhenlun Wei; Yubiao Li; Huimin Gao; Yangge Zhu; Gujie Qian; Jun Yao. New insights into the surface relaxation and oxidation of chalcopyrite exposed to O2 and H2O: A first-principles DFT study. Applied Surface Science 2019, 492, 89 -98.
AMA StyleZhenlun Wei, Yubiao Li, Huimin Gao, Yangge Zhu, Gujie Qian, Jun Yao. New insights into the surface relaxation and oxidation of chalcopyrite exposed to O2 and H2O: A first-principles DFT study. Applied Surface Science. 2019; 492 ():89-98.
Chicago/Turabian StyleZhenlun Wei; Yubiao Li; Huimin Gao; Yangge Zhu; Gujie Qian; Jun Yao. 2019. "New insights into the surface relaxation and oxidation of chalcopyrite exposed to O2 and H2O: A first-principles DFT study." Applied Surface Science 492, no. : 89-98.
Acid mine drainage (AMD) from mine wastes is a critical environmental issue worldwide. It is caused principally by the oxidation of pyrite (FeS2) through a combination of complex reactions (physical, chemical, and biological), often associated with toxic metals/metalloids with varying toxicity, such as As, Cd, Pb and Zn. This paper is specifically focused on the role of reactive silicate minerals (including aluminosilicates) in contributing to pyrite surface passivation (at-source control for reduced AMD generation) and neutralisation processes for long-term AMD mitigation. The neutralisation potential of (alumino)silicate minerals (those readily accessible on-site) to buffer acid generation at reduced pH levels in the long-term is also discussed in the review. Overall, the review aims to present cost-effective solutions, using readily available (alumino)silicate minerals, to provide long-term neutralisation and precursors required for pyrite surface passivation (source control) for sustainable at-source geochemical AMD control.
Yan Zhou; Michael D. Short; Jun Li; Rong Fan; Gujie Qian. Non-carbonate geochemical options for long-term sustainable acid and metalliferous drainage control at-source. Environmental Earth Sciences 2019, 78, 157 .
AMA StyleYan Zhou, Michael D. Short, Jun Li, Rong Fan, Gujie Qian. Non-carbonate geochemical options for long-term sustainable acid and metalliferous drainage control at-source. Environmental Earth Sciences. 2019; 78 (5):157.
Chicago/Turabian StyleYan Zhou; Michael D. Short; Jun Li; Rong Fan; Gujie Qian. 2019. "Non-carbonate geochemical options for long-term sustainable acid and metalliferous drainage control at-source." Environmental Earth Sciences 78, no. 5: 157.
The presence of latent acidity in the form of the jarosite-alunite mineral group complicates assessment of the rates of acid and metalliferous drainage (AMD) generation from potentially acid-forming waste rocks and tailings. To enable better prediction of the contributions from these secondary sulfate minerals, the relationships between pH and the rate of dissolution for natrojarosite and alunite, for comparison with pyrite, have been determined. In single mineral unstirred systems, the dissolution rates of natrojarosite and alunite in the pH range 2–7 were in the range of 10−14 to 10−13 mol m−2 s−1 and were found to be slowest at pH 3.4 and 5.5, respectively. At pH above these respective minima, alunite and natrojarosite dissolution results in acid release. The surface area-normalised dissolution rates of both minerals were 2–3 orders of magnitude slower than that of pyrite under the same conditions, and were 2–4 orders of magnitude slower than the rates of stirred dissolution of synthetic jarosite and alunite reported in the literature. In mixed mineral mini-column dissolution tests, pyrite oxidation proceeded at almost the same rate in the longer term (>50 days), regardless of the presence or absence of natrojarosite or alunite. As the presence of these secondary sulfate minerals does not impact significantly on pyrite oxidation, their contributions to AMD can be taken into account separately enabling accurate calculation of the neutralisation rates needed to effectively manage AMD.
Gujie Qian; Rong Fan; Michael Short; Russell C. Schumann; Jun Li; Yubiao Li; Roger St.C. Smart; Andrea R. Gerson. Evaluation of the rate of dissolution of secondary sulfate minerals for effective acid and metalliferous drainage mitigation. Chemical Geology 2018, 504, 14 -27.
AMA StyleGujie Qian, Rong Fan, Michael Short, Russell C. Schumann, Jun Li, Yubiao Li, Roger St.C. Smart, Andrea R. Gerson. Evaluation of the rate of dissolution of secondary sulfate minerals for effective acid and metalliferous drainage mitigation. Chemical Geology. 2018; 504 ():14-27.
Chicago/Turabian StyleGujie Qian; Rong Fan; Michael Short; Russell C. Schumann; Jun Li; Yubiao Li; Roger St.C. Smart; Andrea R. Gerson. 2018. "Evaluation of the rate of dissolution of secondary sulfate minerals for effective acid and metalliferous drainage mitigation." Chemical Geology 504, no. : 14-27.
The aim of this study was to test the performance of a novel method for acid rock drainage (ARD) control through the formation of Al(OH)3-doped passivating surface layers on pyrite. At pH 2.0 and 4.0, there was no obvious inhibition of the pyrite oxidation rate on addition of 20 mg L-1 Al3+ (added as AlCl3•6H2O). In comparison, the pyrite oxidation rate at circum-neutral pH (7.4 ± 0.4) decreased with increasing added Al3+ with ≈98% reduction in long-term (282 days) dissolution rates in the presence of 20 mg L-1 Al3+. Al3+ was added to the solution and allowed to equilibrate prior to pyrite addition (2 g L-1). Consequently almost all Al3+ (> 99.9%) was initially present as aluminium hydroxide precipitates at pH 7.4. X-ray photoelectron spectroscopy analysis showed a significant concentration of Al3+ (20.3 at.%) on the pyrite surface reacted at pH 7.4 with 20 mg L-1 added Al3+, but no Al3+ on pyrite surfaces reacted at pH 2.0 and 4.0 with added Al3+. Transmission electron microscopy and synchrotron X-ray absorption near edge spectroscopy analyses indicated that compact surface layers containing both goethite and amorphous or nano-crystalline Al(OH)3 formed in the presence of 20 mg L-1 Al3+ at circum-neutral pH, in contrast to the porous goethite surface layers formed on pyrite dissolved in the absence of Al3+ under otherwise identical conditions. This work demonstrates the potential for novel Al-based pyrite passivation of relevance to the mining industry where suitable Al-rich waste materials are available for ARD control interventions.
Yan Zhou; Rong Fan; Michael Short; Jun Li; Russell C. Schumann; Haolan Xu; Roger St. C. Smart; Andrea R. Gerson; Gujie Qian. Formation of Aluminum Hydroxide-Doped Surface Passivating Layers on Pyrite for Acid Rock Drainage Control. Environmental Science & Technology 2018, 52, 11786 -11795.
AMA StyleYan Zhou, Rong Fan, Michael Short, Jun Li, Russell C. Schumann, Haolan Xu, Roger St. C. Smart, Andrea R. Gerson, Gujie Qian. Formation of Aluminum Hydroxide-Doped Surface Passivating Layers on Pyrite for Acid Rock Drainage Control. Environmental Science & Technology. 2018; 52 (20):11786-11795.
Chicago/Turabian StyleYan Zhou; Rong Fan; Michael Short; Jun Li; Russell C. Schumann; Haolan Xu; Roger St. C. Smart; Andrea R. Gerson; Gujie Qian. 2018. "Formation of Aluminum Hydroxide-Doped Surface Passivating Layers on Pyrite for Acid Rock Drainage Control." Environmental Science & Technology 52, no. 20: 11786-11795.
Although the acid generating properties of pyrite (FeS2) have been studied extensively, the impact of galvanic interaction on pyrite oxidation, and the implications for acid and metalliferous drainage, remains largely unexplored. The relative galvanic effects on pyrite dissolution were found to be consistent with relative sulfide mineral surface area ratios with sphalerite (ZnS) having greater negative impact in batch leach tests (sulfide minerals only, controlled pH) and galena (PbS) having greater negative impact in kinetic leach column tests (KLCs, uncontrolled pH, >85 wt% silicate minerals). In contrast the presence of pyrite resulted consistently in greater increase in galena than sphalerite leaching suggesting that increased anodic leaching is dependent on the difference in anodic and cathodic sulfide mineral rest potentials. Acidity increases occurred after 44, 20 and 12 weeks in the pyrite-galena, pyrite-sphalerite and the pyrite containing KLCs. Thereafter acid generation rates were similar with the Eh consistently above the rest potential of pyrite (660 mV, SHE). This suggests that treatment of waste rocks or tailings, to establish and maintain low Eh conditions, may help to sustain protective galvanic interactions and that monitoring of Eh of leachates is potentially a useful indicator for predicting changes in acid generation behaviour.
Gujie Qian; Rong Fan; Michael Short; Russell C. Schumann; Jun Li; Roger St.C. Smart; Andrea R. Gerson. The Effects of Galvanic Interactions with Pyrite on the Generation of Acid and Metalliferous Drainage. Environmental Science & Technology 2018, 52, 5349 -5357.
AMA StyleGujie Qian, Rong Fan, Michael Short, Russell C. Schumann, Jun Li, Roger St.C. Smart, Andrea R. Gerson. The Effects of Galvanic Interactions with Pyrite on the Generation of Acid and Metalliferous Drainage. Environmental Science & Technology. 2018; 52 (9):5349-5357.
Chicago/Turabian StyleGujie Qian; Rong Fan; Michael Short; Russell C. Schumann; Jun Li; Roger St.C. Smart; Andrea R. Gerson. 2018. "The Effects of Galvanic Interactions with Pyrite on the Generation of Acid and Metalliferous Drainage." Environmental Science & Technology 52, no. 9: 5349-5357.
Acid and metalliferous release occurring when sulfide (principally pyrite)-containing rock from mining activities and from natural environments is exposed to the elements is acknowledged as a major environmental problem. Acid rock drainage (ARD) management is both challenging and costly for operating and legacy mine sites. Current technological solutions are expensive and focused on treating ARD on release rather than preventing it at source. We describe here a viable, practical mechanism for reduced ARD through the formation of silicate-stabilized iron oxyhydroxide surface layers. Without silicate, oxidized pyrite particles form an overlayer of crystalline goethite or lepidocrocite with porous structure. With silicate addition, a smooth, continuous, coherent and apparently amorphous iron oxyhydroxide surface layer is observed, with consequent pyrite dissolution rates reduced by more than 90% at neutral pH. Silicate is structurally incorporated within this layer and inhibits the phase transformation from amorphous iron (oxy)hydroxide to goethite, resulting in pyrite surface passivation. This is confirmed by computational simulation, suggesting that silicate-doping of a pseudoamorphous iron oxyhydroxide (ferrihydrite structure) is thermodynamically more stable than the equivalent undoped structure. This mechanism and its controlling factors are described. As a consequence of the greatly reduced acid generation rate, neutralization from on-site available reactive silicate minerals may be used to maintain neutral pH, after initial limestone addition to achieve neutral pH, thus maintaining the integrity of these layers for effective ARD management.
Rong Fan; Michael Short; Sheng-Jia Zeng; Gujie Qian; Jun Li; Russell C. Schumann; Nobuyuki Kawashima; Roger St. C. Smart; Andrea R. Gerson. The Formation of Silicate-Stabilized Passivating Layers on Pyrite for Reduced Acid Rock Drainage. Environmental Science & Technology 2017, 51, 11317 -11325.
AMA StyleRong Fan, Michael Short, Sheng-Jia Zeng, Gujie Qian, Jun Li, Russell C. Schumann, Nobuyuki Kawashima, Roger St. C. Smart, Andrea R. Gerson. The Formation of Silicate-Stabilized Passivating Layers on Pyrite for Reduced Acid Rock Drainage. Environmental Science & Technology. 2017; 51 (19):11317-11325.
Chicago/Turabian StyleRong Fan; Michael Short; Sheng-Jia Zeng; Gujie Qian; Jun Li; Russell C. Schumann; Nobuyuki Kawashima; Roger St. C. Smart; Andrea R. Gerson. 2017. "The Formation of Silicate-Stabilized Passivating Layers on Pyrite for Reduced Acid Rock Drainage." Environmental Science & Technology 51, no. 19: 11317-11325.
Yubiao Li; Gujie Qian; Paul L. Brown; Andrea R. Gerson. Chalcopyrite dissolution: Scanning photoelectron microscopy examination of the evolution of sulfur species with and without added iron or pyrite. Geochimica et Cosmochimica Acta 2017, 212, 33 -47.
AMA StyleYubiao Li, Gujie Qian, Paul L. Brown, Andrea R. Gerson. Chalcopyrite dissolution: Scanning photoelectron microscopy examination of the evolution of sulfur species with and without added iron or pyrite. Geochimica et Cosmochimica Acta. 2017; 212 ():33-47.
Chicago/Turabian StyleYubiao Li; Gujie Qian; Paul L. Brown; Andrea R. Gerson. 2017. "Chalcopyrite dissolution: Scanning photoelectron microscopy examination of the evolution of sulfur species with and without added iron or pyrite." Geochimica et Cosmochimica Acta 212, no. : 33-47.
The effective control and treatment of acid mine drainage (AMD) from sulfide-containing mine wastes is of fundamental importance for current and future long-term sustainable and cost-effective mining industry operations, and for sustainable management of legacy AMD sites. Historically, AMD management has focused on the use of expensive neutralising chemicals to treat toxic leachates. Accordingly, there is a need to develop more cost-effective and efficient methods to prevent AMD at source. Laboratory kinetic leach column experiments, designed to mimic a sulfide-containing waste rock dump, were conducted to assess the potential of organic waste carbon supplements to stimulate heterotrophic microbial growth, and supress pyrite oxidation and AMD production. Microbiological results showed that the addition of biosolids was effective at maintaining high microbial heterotroph populations and preventing AMD generation over a period of 80 weeks, as verified by leachate chemistry and electron microscopy analyses. This research contributes to the ongoing development of a cost effective, multi-barrier geochemical-microbial control strategy for reduced mineral sulfide oxidation rates at source.
Omy T. Ogbughalu; Andrea R. Gerson; Gujie Qian; Roger St. C. Smart; Russell C. Schumann; Nobuyuki Kawashima; Rong Fan; Jun Li; Michael D. Short. Heterotrophic Microbial Stimulation through Biosolids Addition for Enhanced Acid Mine Drainage Control. Minerals 2017, 7, 105 .
AMA StyleOmy T. Ogbughalu, Andrea R. Gerson, Gujie Qian, Roger St. C. Smart, Russell C. Schumann, Nobuyuki Kawashima, Rong Fan, Jun Li, Michael D. Short. Heterotrophic Microbial Stimulation through Biosolids Addition for Enhanced Acid Mine Drainage Control. Minerals. 2017; 7 (6):105.
Chicago/Turabian StyleOmy T. Ogbughalu; Andrea R. Gerson; Gujie Qian; Roger St. C. Smart; Russell C. Schumann; Nobuyuki Kawashima; Rong Fan; Jun Li; Michael D. Short. 2017. "Heterotrophic Microbial Stimulation through Biosolids Addition for Enhanced Acid Mine Drainage Control." Minerals 7, no. 6: 105.
Laboratory kinetic leach column (KLC) tests were carried out to define the conditions required to control acid generation from a highly reactive, potentially acid-forming (PAF) iron ore waste rock. It was found that lime addition (0.1 wt % blended) plus either blending of silicates (25 wt % K-feldspar and 25 wt % chlorite), or addition of a non-acid forming (NAF) top cover containing about 10% dolomite (PAF:NAF = 5:1 wt %), when watered/flushed with lime-saturated water, greatly reduced acid generation as compared to the control KLC (PAF alone, watered/flushed with Milli-Q water), but did not result in circum-neutral pH as required for pyrite surface passivation and effective acid and metalliferous drainage (AMD) mitigation. In contrast, the combined use of these treatments—blended lime and silicates with an NAF cover and watering/flushing with lime-saturated water—resulted in leachate pH of 12 (up to 24 weeks). Mass balance calculations for Ca2+ and scanning electron microscopy (SEM) analyses suggest that calcite or gypsum may have formed in the NAF-amended KLCs and lime with added silicate KLC. Although the combined approach in the form trialled here may not be practical or cost-effective, control of a highly reactive natural PAF waste by pyrite surface passivation appears to be possible, and an improved treatment methodology (e.g., slightly increased lime blending without the need for further lime watering/flushing) could usefully be examined in the future.
Yan Zhou; Michael D. Short; Jun Li; Russell C. Schumann; Roger St. C. Smart; Andrea R. Gerson; Gujie Qian. Control of Acid Generation from Pyrite Oxidation in a Highly Reactive Natural Waste: A Laboratory Case Study. Minerals 2017, 7, 89 .
AMA StyleYan Zhou, Michael D. Short, Jun Li, Russell C. Schumann, Roger St. C. Smart, Andrea R. Gerson, Gujie Qian. Control of Acid Generation from Pyrite Oxidation in a Highly Reactive Natural Waste: A Laboratory Case Study. Minerals. 2017; 7 (6):89.
Chicago/Turabian StyleYan Zhou; Michael D. Short; Jun Li; Russell C. Schumann; Roger St. C. Smart; Andrea R. Gerson; Gujie Qian. 2017. "Control of Acid Generation from Pyrite Oxidation in a Highly Reactive Natural Waste: A Laboratory Case Study." Minerals 7, no. 6: 89.
Acid and metalliferous drainage (AMD) is broadly accepted to be a major global environmental problem facing the mining industry, requiring expensive management and mitigation. A series of laboratory-scale kinetic leach column (KLC) experiments, using both synthetic and natural mine wastes, were carried out to test the efficacy of our pyrite passivation strategy (developed from previous research) for robust and sustainable AMD management. For the synthetic waste KLC tests, initial treatment with lime-saturated water was found to be of paramount importance for maintaining long-term circum-neutral pH, favourable for the formation and preservation of the pyrite surface passivating layer and reduced acid generation rate. Following the initial lime-saturated water treatment, minimal additional alkalinity (calcite-saturated water) was required to maintain circum-neutral pH for the maintenance of pyrite surface passivation. KLC tests examining natural potentially acid forming (PAF) waste, with much greater peak acidity than that of the synthetic waste, blended with lime (≈2 wt %) with and without natural non-acid-forming (NAF) waste covers, were carried out. The addition of lime and use of NAF covers maintained circum-neutral leachate pH up to 24 weeks. During this time, the net acidity generated was found to be significantly reduced by the overlying NAF cover. If the reduced rate of acidity production from the natural PAF waste is sustained, the addition of smaller (more economically-feasible) amounts of lime, together with application of NAF wastes as covers, could be trialled as a potential cost-effective AMD mitigation strategy.
Gujie Qian; Russell C. Schumann; Jun Li; Michael D. Short; Rong Fan; Yubiao Li; Nobuyuki Kawashima; Yan Zhou; Roger St. C. Smart; Andrea R. Gerson. Strategies for Reduced Acid and Metalliferous Drainage by Pyrite Surface Passivation. Minerals 2017, 7, 42 .
AMA StyleGujie Qian, Russell C. Schumann, Jun Li, Michael D. Short, Rong Fan, Yubiao Li, Nobuyuki Kawashima, Yan Zhou, Roger St. C. Smart, Andrea R. Gerson. Strategies for Reduced Acid and Metalliferous Drainage by Pyrite Surface Passivation. Minerals. 2017; 7 (3):42.
Chicago/Turabian StyleGujie Qian; Russell C. Schumann; Jun Li; Michael D. Short; Rong Fan; Yubiao Li; Nobuyuki Kawashima; Yan Zhou; Roger St. C. Smart; Andrea R. Gerson. 2017. "Strategies for Reduced Acid and Metalliferous Drainage by Pyrite Surface Passivation." Minerals 7, no. 3: 42.
Gujie Qian; Yubiao Li; Jun Li; Andrea R. Gerson. Consideration of enthalpic and entropic energy contributions to the relative rates of chalcopyrite dissolution in the presence of aqueous cationic impurities. International Journal of Mineral Processing 2017, 159, 42 -50.
AMA StyleGujie Qian, Yubiao Li, Jun Li, Andrea R. Gerson. Consideration of enthalpic and entropic energy contributions to the relative rates of chalcopyrite dissolution in the presence of aqueous cationic impurities. International Journal of Mineral Processing. 2017; 159 ():42-50.
Chicago/Turabian StyleGujie Qian; Yubiao Li; Jun Li; Andrea R. Gerson. 2017. "Consideration of enthalpic and entropic energy contributions to the relative rates of chalcopyrite dissolution in the presence of aqueous cationic impurities." International Journal of Mineral Processing 159, no. : 42-50.
To better understand chalcopyrite leach mechanisms and kinetics, for improved Cu extraction during hydrometallurgical processing, chalcopyrite leaching has been conducted at solution redox potential 750 mV, 35–75 °C, and pH 1.0 with and without aqueous iron addition, and pH 1.5 and 2.0 without aqueous iron addition. The activation energy (Ea) values derived indicate chalcopyrite dissolution is initially surface chemical reaction controlled, which is associated with the activities of Fe3+ and H+ with reaction orders of 0.12 and −0.28, respectively. A surface diffusion controlled mechanism is proposed for the later leaching stage with correspondingly low Ea values. Surface analyses indicate surface products (predominantly Sn2− and S0) did not inhibit chalcopyrite dissolution, consistent with the increased surface area normalised leach rate during the later stage. The addition of aqueous iron plays an important role in accelerating Cu leaching rates, especially at lower temperature, primarily by reducing the length of time of the initial surface chemical reaction controlled stage.
Yubiao Li; Zhenlun Wei; Gujie Qian; Jun Li; Andrea R. Gerson. Kinetics and Mechanisms of Chalcopyrite Dissolution at Controlled Redox Potential of 750 mV in Sulfuric Acid Solution. Minerals 2016, 6, 83 .
AMA StyleYubiao Li, Zhenlun Wei, Gujie Qian, Jun Li, Andrea R. Gerson. Kinetics and Mechanisms of Chalcopyrite Dissolution at Controlled Redox Potential of 750 mV in Sulfuric Acid Solution. Minerals. 2016; 6 (3):83.
Chicago/Turabian StyleYubiao Li; Zhenlun Wei; Gujie Qian; Jun Li; Andrea R. Gerson. 2016. "Kinetics and Mechanisms of Chalcopyrite Dissolution at Controlled Redox Potential of 750 mV in Sulfuric Acid Solution." Minerals 6, no. 3: 83.
This study combined physical data from synchrotron SAXS, FTIR and microscopy with in-silico molecular structure predictions and mathematical modeling to examine inulin adjuvant particle formation and structure. The results show that inulin polymer chains adopt swollen random coil in solution. As precipitation occurs from solution, interactions between the glucose end group of one chain and a fructose group of an adjacent chain help drive organized assembly, initially forming inulin ribbons with helical organization of the chains orthogonal to the long-axis of the ribbon. Subsequent aggregation of the ribbons results in the layered semicrystalline particles previously shown to act as potent vaccine adjuvants. γ-Inulin adjuvant particles consist of crystalline layers 8.5 nm thick comprising helically organized inulin chains orthogonal to the plane of the layer. These crystalline layers alternate with amorphous layers 2.4 nm thick, to give overall particle crystallinity of 78%.
Thomas G. Barclay; Harinda Rajapaksha; Alagu Thilagam; Gujie Qian; Milena Ginic-Markovic; Peter D. Cooper; Andrea Gerson; Nikolai Petrovsky. Physical characterization and in silico modeling of inulin polymer conformation during vaccine adjuvant particle formation. Carbohydrate Polymers 2016, 143, 108 -115.
AMA StyleThomas G. Barclay, Harinda Rajapaksha, Alagu Thilagam, Gujie Qian, Milena Ginic-Markovic, Peter D. Cooper, Andrea Gerson, Nikolai Petrovsky. Physical characterization and in silico modeling of inulin polymer conformation during vaccine adjuvant particle formation. Carbohydrate Polymers. 2016; 143 ():108-115.
Chicago/Turabian StyleThomas G. Barclay; Harinda Rajapaksha; Alagu Thilagam; Gujie Qian; Milena Ginic-Markovic; Peter D. Cooper; Andrea Gerson; Nikolai Petrovsky. 2016. "Physical characterization and in silico modeling of inulin polymer conformation during vaccine adjuvant particle formation." Carbohydrate Polymers 143, no. : 108-115.
The dissolution of chalcopyrite in association with pyrite in mine waste results in the severe environmental issue of acid and metalliferous drainage (AMD). To better understand chalcopyrite dissolution, and the impact of chalcopyrite’s galvanic interaction with pyrite, chalcopyrite dissolution has been examined at 75 °C, pH 1.0, in the presence of quartz (as an inert mineral) and pyrite. The presence of pyrite increased the chalcopyrite dissolution rate by more than five times at Eh of 650 mV (SHE) (Cu recovery 2.5 cf. 12% over 132 days) due to galvanic interaction between chalcopyrite and pyrite. Dissolution of Cu and Fe was stoichiometric and no pyrite dissolved. Although the chalcopyrite dissolution rate at 750 mV (SHE) was approximately four-fold greater (Cu recovery of 45% within 132 days) as compared to at 650 mV in the presence of pyrite, the galvanic interaction between chalcopyrite and pyrite was negligible. Approximately all of the sulfur from the leached chalcopyrite was converted to S0 at 750 mV, regardless of the presence of pyrite. At this Eh approximately 60% of the sulfur associated with pyrite dissolution was oxidised to S0 and the remaining 40% was released in soluble forms, e.g., SO42−.
Yubiao Li; Gujie Qian; Jun Li; Andrea R. Gerson. Chalcopyrite Dissolution at 650 mV and 750 mV in the Presence of Pyrite. Metals 2015, 5, 1566 -1579.
AMA StyleYubiao Li, Gujie Qian, Jun Li, Andrea R. Gerson. Chalcopyrite Dissolution at 650 mV and 750 mV in the Presence of Pyrite. Metals. 2015; 5 (3):1566-1579.
Chicago/Turabian StyleYubiao Li; Gujie Qian; Jun Li; Andrea R. Gerson. 2015. "Chalcopyrite Dissolution at 650 mV and 750 mV in the Presence of Pyrite." Metals 5, no. 3: 1566-1579.
Yubiao Li; Gujie Qian; Jun Li; Andrea R. Gerson. Kinetics and roles of solution and surface species of chalcopyrite dissolution at 650 mV. Geochimica et Cosmochimica Acta 2015, 161, 188 -202.
AMA StyleYubiao Li, Gujie Qian, Jun Li, Andrea R. Gerson. Kinetics and roles of solution and surface species of chalcopyrite dissolution at 650 mV. Geochimica et Cosmochimica Acta. 2015; 161 ():188-202.
Chicago/Turabian StyleYubiao Li; Gujie Qian; Jun Li; Andrea R. Gerson. 2015. "Kinetics and roles of solution and surface species of chalcopyrite dissolution at 650 mV." Geochimica et Cosmochimica Acta 161, no. : 188-202.
Gujie Qian; Yubiao Li; Andrea R. Gerson. Applications of surface analytical techniques in Earth Sciences. Surface Science Reports 2015, 70, 86 -133.
AMA StyleGujie Qian, Yubiao Li, Andrea R. Gerson. Applications of surface analytical techniques in Earth Sciences. Surface Science Reports. 2015; 70 (1):86-133.
Chicago/Turabian StyleGujie Qian; Yubiao Li; Andrea R. Gerson. 2015. "Applications of surface analytical techniques in Earth Sciences." Surface Science Reports 70, no. 1: 86-133.