A system of light harvesting, sensing and regulating was designed based on the photo-thermal and Seebeck effect of flexible CuO nanostructures. [email protected] meshes were prepared via self-oxidation of Cu mesh and utilized as the photo-thermal material. Upon irradiation by visible light, the temperature of the [email protected] mesh dramatically increases. The temperature difference between the irradiated and non-irradiated parts of the [email protected] mesh produced a measurable voltage output due to the Seebeck effect. The generated voltage was then converted into a digital signal to control a rotary neutral-density disc to filter the received light. This enabled regulation of the intensity of the incident light at a selected region. This system is cost effective and has potential applications in greenhouses, factories and smart buildings to minimize energy consumption and improve wellbeing.
Pyrrhotite, a significant sulfide mineral in base metal sulfide deposits, exists in various superstructures including magnetic (4C) and non-magnetic (5C and 6C) types. Identifying and quantifying pyrrhotite superstructures in an ore sample has been a challenge, hindering efforts to improve pyrrhotite rejection in copper–gold flotation. This study employed synchrotron X-ray powder diffraction (S-XRPD) analysis to quantify pyrrhotite superstructures in the concentrates obtained from flotation of a copper–gold ore after grinding with forged steel and 30% chromium grinding media. S-XRPD demonstrated a superior capability in detecting characteristic peaks of 4C, 5C and 6C pyrrhotite superstructures compared to conventional XRPD. Utilizing the Rietveld refinement method, the identified pyrrhotite superstructures were quantified. These findings were successfully validated through independent X-ray fluorescence analysis on elemental compositions. The quantification work demonstrated that 30% chromium grinding media enhanced the floatability of all pyrrhotite superstructures over forged steel grinding media and each pyrrhotite superstructure in the copper–gold ore resembled a copper sulfide mineral rather than pyrite in response to grinding media during flotation. This research highlights the potential of S-XRPD as an effective technique for identifying and quantifying pyrrhotite superstructures in ore samples and determining their flotation behaviors.
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.
Nickel is typically distributed across several fine-grained minerals in nickel laterites, formed by intense tropical weathering of ultramafic rocks. Indonesia accounts for approximately 16% of the world’s lateritic nickel reserves, which play an increasing role in global nickel production. However, relatively few geochemical studies of Indonesian laterites have been undertaken and quantification of Ni speciation is unclear. In this study the Ni geochemistry of an Indonesian laterite composed of limonite and saprolite has been examined using synchrotron microprobe analysis (microprobe X-ray fluorescence microscopy, μ-XFM; microprobe X-ray diffraction, μ-XRD; microprobe X-ray absorption spectroscopy; μ-XAS) and bulk XAS. This approach provides semi-quantitative species specific information not readily obtainable using traditional laboratory methods that are hampered by the fine-grained heterogeneous nature of laterites. In the limonite 16 ± 4% of the Ni was found to be substituted for Al in lithiophorite with 26 ± 7% being associated with lizardite (a serpentine) substituted for Mg. A minor proportion of the Ni is adsorbed onto the Mn layers of phyllomanganate (e.g., lithiophorite). However the majority of the Ni, 58 ± 15% is substituted for Fe in goethite. The majority of the Ni (85 ± 21%) within the saprolite is found to be associated with lizardite, the predominant mineral. A few relatively large Ni asbolane grains are also observed, which account for 14 ± 3% of the Ni with the remaining 1 ± 0.3% of the Ni replacing Fe within goethite.
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