Search Results (89)

This study characterises low-grade copper ore tailings from a conventional flotation circuit to evaluate their feasibility for further processing. A suite of advanced analytical techniques, such as X-ray fluorescence (XRF), inductively coupled plasma (ICP), X-ray diffraction (XRD), and the quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN), was employed to assess the elemental, chemical, and mineralogical composition of the tailings. Chalcopyrite was identified as the dominant copper-bearing mineral phase, predominantly locked within iron oxides and silicate gangue minerals. The QEMSCAN results showed that chalcopyrite was only partially liberated, which highlights the complex mineral intergrowths that hinder efficient recovery. Based on the mineralogical characteristics, the applicability of various processing techniques, including conventional froth flotation, advanced flotation methods [including Hydrofloat^TM, Jameson, and the Reflux Flotation Cell (RFC)], magnetic separation, and gravity separation, was evaluated. Overall, this study indicates that incorporating HydroFloat™, the Jameson Cell, and the RFC into the flotation circuit could greatly improve copper recovery from tailings. This study also identified rare earth elements (REEs) as potential by-products of copper recovery, so it is an additional opportunity for resource recovery. This paper contributes to sustainable mining practices and resource optimization by highlighting the characteristics and recovery of valuable minerals from tailings. Full article

Biological reduction of sulphates has gradually replaced unit chemical processes for the treatment of acid mine drainage (AMD), which exerts a significant environmental impact due to its elevated acidity and high concentrations of heavy metals. Bioremediation is optimally suited for the treatment of AMD because it is cost-effective and efficient. Anaerobic bioremediation employing sulphate-reducing bacteria (SRB) presents a promising solution by facilitating the reduction of sulphate to sulphide. The formed can precipitate and immobilise heavy metals, assisting them in their removal from contaminated wastewater. This paper examines the current status of SRB-based bioremediation, with an emphasis on recent advances in microbial processes, reactor design, and AMD treatment efficiencies. Reviewed studies showed that SRB-based bioreactors can achieve up to 93.97% of sulphate reduction, with metal recovery rates of 95% for nickel, 98% for iron and copper, and 99% for zinc under optimised conditions. Furthermore, bioreactors that used glycerol and ethanol as a carbon source improved the efficiency of sulphate reduction, achieving a pH neutralisation from 2.8 to 7.5 within 14 days of hydraulic retention time. Despite the promising results achieved so far, several challenges remain. These include the need for optimal environmental conditions, the management of toxic hydrogen sulphide production, and the economic feasibility of large-scale applications. Future directions are proposed to address these challenges, focusing on the genetic engineering of SRB, integration with other treatment technologies, and the development of cost-effective and sustainable bioremediation strategies. Ultimately, this review provides valuable information to improve the efficiency and scalability of SRB-based remediation methods, contributing to more sustainable mining practices and environmental conservation. To ensure relevance and credibility, relevance and regency were used as criteria for the literature search. The literature sourced is directly related to the subject of the review, and the latest research, typically from the last 5 to 10 years, was prioritised. Full article

Copper is a critical metal required for green energy technologies such as wind turbines and solar cells. However, copper supply is limited by copper recovery from primary copper sulphides (e.g., chalcopyrite-CuFeS₂) due to passivating reaction products. Therefore, this study examined surface ‘passivation’ of primary copper sulphide minerals undergoing coupled dissolution with reprecipitation (CDR) reactions and the associated mineral surface changes in acidic and chloride-rich lixiviants (FeCl₃-only, AlCl₃-rich, NaCl-rich, and CaCl₂-rich lixiviants). Acidic FeCl₃-only, NaCl-rich, and CaCl₂-rich lixiviants resulted in only bornite dissolution and the formation of a residual Cu-S phase and Fe-SO₄ phase on the chalcopyrite surface. In contrast, leaching with the AlCl₃-rich lixiviant resulted in both chalcopyrite and bornite dissolution with limited hydrolysis of Fe³⁺ to Fe-hydroxy sulphates and minimal Fe³⁺ flux inhibition to the copper sulphide minerals surface due to the ion exchange mechanism between Al³⁺ and Fe³⁺. Further, there was preferential formation of an Al-SO₄ phase at consistently high Eh and acidity, thereby a high availability of Fe³⁺ in solution for enhanced copper dissolution from both bornite and chalcopyrite. These findings could serve as a reference for coupled dissolution with reprecipitation reactions during copper sulphide leaching, offering a pathway to more efficient and sustainable copper extraction from low-grade ores. Full article

Phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), has emerged as a promising non-invasive cancer treatment, addressing issues like drug resistance and systemic toxicity common in conventional breast cancer therapies. Recent research has shown that copper sulphide (CuS) nanoparticles and polydopamine (PDA) exhibit exceptional photothermal conversion efficiency under 808 nm near-infrared (NIR) laser irradiation, making them valuable for cancer phototherapy. However, the effectiveness of PDT is limited in hypoxic tumour environments, which are common in many breast cancer types, due to its reliance on local oxygen levels. Moreover, single-modality approaches, including phototherapy, often prove insufficient for complete tumour elimination, despite their therapeutic strength. In this paper, a microfluidic-assisted approach was used to create multifunctional silk-based nanoparticles (SFNPs) encapsulating the chemotherapeutic drug Epirubicin (EPI), the PTT/PDT agent CuS, and the heat-activated, oxygen-independent alkyl radical generator AIPH for combined chemotherapy, PTT, and PDT, with a polydopamine (PDA) coating for enhanced photothermal effects and surface-bound folic acid (FA) for targeted delivery in breast cancer treatment. The synthesised CuS-EPI-AIPH@SF-PDA-FA nanoparticles achieved a controlled size of 378 nm, strong NIR absorption, and high photothermal conversion efficiency. Under 808 nm NIR irradiation, these nanoparticles selectively triggered the release of alkyl radicals and EPI, improving intracellular drug levels and effectively killing various breast cancer cell lines while demonstrating low toxicity to non-cancerous cells. We demonstrate that novel core–shell CuS-EPI-AIPH@SF-PDA-FA NPs have been successfully designed as a multifunctional nanoplatform integrating PTT, PDT, and chemotherapy for targeted, synergistic breast cancer treatment. Full article

This article presents a study on the precipitation of copper from the cyanide leaching solutions used for gold–copper ores, both with and without the addition of a sulphidizer (Na₂S). Mathematical models were developed to summarize the effects of the pH, initial copper concentration, and Na₂S stoichiometric ratio on the precipitation process, using an experimental design based on a probabilistic–deterministic method. Varying the stoichiometric ratio of Na₂S has a minimal impact on the precipitation process. However, the presence of a sulphidizer is significant, as the precipitation process occurs at pH levels of 5 and below. The initial concentration of copper in the solution was identified as the most significant factor. At copper concentrations of 0.34% and 1.55% (pH = 3), the precipitation rates were 51.48% and 47.6%, respectively. This study also determined that the most effective method across the entire range of copper concentrations in the solution was the precipitation of copper in the form of copper cyanide hydrate (CuCN∙nH₂O) without the addition of Na₂S. At copper concentrations of 0.34% and 1.55% (pH = 3), the precipitation rates were 86.47% and 85%, respectively. The pH level was the most significant factor influencing this process, as copper deposition without Na₂S did not occur at a pH of 5. The obtained models allow us to accurately predict the influence of factors on the deposition process. Aided by the mathematical model of precipitation (without Na₂S), we selected the conditions for an enlarged experiment using 20 L of solution (Cu = 0.34%, pH = 3.2), which showed the high efficiency of the method. The calculated recovery amounted to 86%, where practical recovery was 87.2%, and divergence was ≥1.2%. Full article

Grinding conditions affect the flotation of copper sulphide minerals as changes in the properties of the grinding media and their interactions with the sulphide minerals, and between sulphide minerals themselves, affect the chemical environment in the flotation pulp. Galvanic interactions between steel grinding media and sulphide minerals, and between sulphide minerals, can lower the pulp potential, decrease the dissolved oxygen concentration in the mineral slurry, and lead to the dissolution of iron and copper from the media and the minerals. As a result, the formation of hydrophilic iron hydroxides and their adsorption on the copper sulphide minerals can be deleterious to copper flotation while pyrite (when present) can be activated to flotation by dissolved copper lowering the grade of the copper concentrate. Electrochemically less active grinding media (e.g., chrome alloy balls rather than mild steel media) can have beneficial effects on flotation performance due to the lower oxidation of the grinding media and consequently the lower production of oxidised iron species in the pulp. Copper activation of pyrite can be decreased by chemical additions to the pulp. In this paper, relevant experimental data published in the last 15 years are discussed. Full article

The study object was slag from the Balkhash copper smelter, obtained by re-melting anode mud containing nonferrous metals. The process flow for processing these slags includes sintering with Na₂SO₄, Na₂CO₃, and coal, followed by soda-alkaline leaching of the sinter and extraction of metals from the solution into marketable products. Since sintering is the main operation providing high selectivity, the composition of the products of this process was studied. The main transformations during sintering were determined, and the optimal parameters were identified. The structures of slags and sintered materials obtained during the experiments were studied by electron-probe microanalysis. Sintering was performed at 600–800 °C. The best results for sulphidization of slag components were obtained at 800 °C; a further increase in temperature leads to the smelting of sinter particles and slows down sulphidization. The optimal quantities of additives, based on the weight of the slag, are Na₂SO₄—45%, Na₂CO₃—15%, and reducing agent—41%, with a sintering time of 2 h. These conditions enable the sulphidization of non-ferrous metals in the slag to the entire depth of the polymetallic globules. The distinct concentration of harmful impurities (Ni, As, and Sb) was observed in the fine structure of the polymetallic globules. Full article

Several Jurassic, ophiolite-hosted Cu-Zn VMS deposits occur in Tuscany. They are hosted by tectonic units of oceanic affinity (Ligurian Units), such as the well-known deposits of nearby Liguria. Industrial production was small and definitively ceased in the 1960s. Locally, massive ore (chalcopyrite-bornite-chalcocite) with an exceptionally high grade was found. The Montecatini Val di Cecina mine exploited the largest “bonanza” and, for few decades in the 19th century, became one of the most profitable copper mines in Europe. This study provides an updated review of these deposits. Tuscan Cu-Zn VMSs mostly occur in proximity of the contact between the serpentinite-gabbro basement and the overlying basalts. Chalcopyrite-pyrite stockworks occur in serpentinite-gabbro cut by dolerite dykes, while the largest massive sulphide bodies are hosted by polymictic-monomictic breccias at the base of pillow basalts. Early chalcopyrite ores were mechanically–chemically reworked and upgraded to bornite-rich nodular ore embedded in a chlorite, calcic amphibole, Fe-rich serpentine, quartz, andradite, ilvaite, and xonotlite assemblage. This bornite-rich ore contains substantial amount of sphalerite and pyrite and ubiquitous grains of clausthalite, hessite, tellurium, and gold. They represent a prime example of the sub-seafloor portion of a hybrid mafic-ultramafic oceanic hydrothermal system formed in an OCC along the slow spreading ridge of the Jurassic Piedmont-Ligurian Ocean. The peculiar mineralogical–textural character of the bornite-rich ore was driven by an interface coupled dissolution–precipitation process mediated by fluids. Full article

A full potential all-electron density functional method within generalized gradient approximation is used herein to investigate correlations of the electronic, elastic and thermo-electric transport properties of cubic copper sulphide and copper selenide. The electronic band structure and density of states suggest a metallic behaviour with a zero-energy band gap for both materials. Elastic property calculations suggest stiff materials, with bulk to shear modulus ratios of 0.35 and 0.44 for Cu₂S and Cu₂Se, respectively. Thermo-electric transport properties were estimated using the Boltzmann transport approach. The Seebeck coefficient, electrical conductivity, thermal conductivity and power factor all suggest a potential p-type conductivity for α-Cu₂S and n-type conductivity for α-Cu₂Se. Full article

Flotation performance can significantly be affected by seasonal variations due to the changes in water temperature and pulp temperature, type and concentration of dissolved ions in process water. Extreme temperature conditions could be the major factor affecting flotation performance and mask the influence of water chemistry. Therefore, the interactive effects of the temperature and water chemistry should be taken into consideration, particularly for mine sites experiencing extreme temperature conditions. In this paper, effects of temperature, sulphate (SO₄²⁻), thiosulphate (S₂O₃²⁻) and calcium (Ca²⁺) ions on the flotation performance of a Cu-Pb-Zn complex sulfide ore were investigated using a statistical experimental design and modelling approach. The results were evaluated using ANOVA and regression analysis to determine the significant parameters and derive individual regression models for each flotation response using Design Expert software version 6.0.8. Individual regression models were developed for mass pull, water recovery, grade and recovery of the sulfide minerals using the statistically significant main effects and their interactions. The models were used to determine the concentration of the dissolved ions and pulp temperature required to achieve the maximum zinc recovery, maximum zinc grade or the optimum zinc grade and recovery. The results showed that the water chemistry (i.e., the concentrations of Ca²⁺, SO₄²⁻ and S₂O₃²⁻) affected the flotation performance significantly at low temperature (25 °C). At high pulp temperature (60 °C), however, the temperature was the dominant parameter and masked the effects of water chemistry. Details of the statistical experimental design, discussions of the effects of experimental factors and their interactions on flotation performance, and the development of regression models are presented in this paper. Full article

The depletion of the ore reserves in the world necessitates the search for secondary sources such as waste products (tailings and slag). The treatment and cleaning up of such secondary sources also has a positive impact on the environment. A smelter in Namibia we examined had historic slag which accumulated over decades of its operating life, thus posing the challenge of how best to collect representative samples to evaluate and propose viable methods of recovering contained metals. In this study, analytical and mineralogical characterization of the slag was performed using X-ray fluorescence (XRF) analysis, atomic absorption spectrometer (AAS), ICP-OES, scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) analysis, and optical microscopy analysis. The chemical analyses showed that the metal values contained in the slag were mainly copper, lead, and zinc whose average contents were approximately 0.35% Cu, 3% Pb, and 5.5% Zn. About 10.5% Fe was also contained in the slag. Germanium was detected by scanning electron microscopy, but was however below detection limits of the chemical analysis equipment used. Based on the results, approximate conditions under which the different slag phases were formed were estimated and the recovery routes for the various metals were proposed. Analysis by both optical and scanning electron microscopy revealed that Zn and Fe occurred mainly in association with O as oxides, while Cu and Pb were mainly associated with S as sulphides. The slag consisted of three different phases, namely the silicate phase (slag), metallic phase and the sulphide phases. The phases in the slag were mainly silicate phases as well as metallic and sulphide phases. It was observed that the metallic and sulphide phases were dominant in the finer size fractions (−75 µm) whereas the sulphide phase was also present in the coarser size fractions (+300 µm). An important finding from the microscopy examination was that the sulphide phases were interstitial and could be liberated from the slag. This finding meant that liberation and subsequent concentration of the sulphide phases was feasible using conventional processing techniques. Full article

Copper, uranium, and rare earth element (REE) mineralisation occurs in hydrocarbon-bearing Devonian continental sandstones in southwest Orkney, Scotland. The aeolian Yesnaby Sandstone Formation and fluvial Harra Ebb Sandstone Formation were mineralised following oil emplacement. The REE-bearing APS mineral florencite is particularly associated with bituminous nodules, many of which contain brannerite. Subsequently hydrothermal copper and other sulphides, and barite, further mineralised the oil reservoir at a temperature of ~190 °C. Oil was mobilised through mineralised fractures at this stage. Biodegradation of the oil occurred later, following the Carboniferous-Permian uplift. The occurrence confirms that Cu-APS mineralisation is possible in relatively low-temperature regimes in sedimentary basins. Full article

Geological and radiometric studies of outcrops aided by extensive subsurface exploration through drill holes in an otherwise soil-covered terrain revealed the existence of low grades, medium tonnage, and metasomatite types of polymetallic uranium deposits at Rohil in India. Microscopic studies, electronprobe micro analyses, and geochemical analyses of samples from lodes indicate the polymetallic nature of mineralisation involving copper and molybdenum, in addition to uranium. Wide variations in the composition of fluid (S-, F-, P-, and O-rich) led to the formation of sulphides, fluorite, U-phosphosilicate, quartz, and magnetite, respectively, and are associated with uraninite. Litho-geochemical analyses from the Rohil deposit indicate multifarious metasomatic alterations associated with polymetallic mineralisation occurring in veins. The major mineralogical and metasomatic controls on rock compositions and the extent of material transfer processes that influenced the host rocks and mineralisati on are quantified by molar element ratio studies and alteration plots. General element ratio (GER) diagrams on chemical analyses of rock samples reveal albitisation and chloritisation as major and microclinisation, sericitisation, carbonatisation, and silicification as minor wall rock alterations associated with ore mineralisation. The alteration box plot between the chlorite–carbonate–pyrite index (CCPI) and the Ishikawa alteration index (AI) indicates the influence of hydrothermal activity and dominance of both albitisation and chloritisation. The ore zone is controlled by meso- and microstructures and the geometry of the soda- and potash-metasomatised zone around hydrothermal veins. This zone contains several anastomosing mineralised veins defined by a prominent joint that is set in quartzite that strikes subparallel to the axial surface of the F₂ isoclinal folds and the pervasive schistosity S₁ in the quartz–feldspar–biotite schist. Aventurisation of albite and microcline, established through electron probe micro analyses, can be considered as a pathfinder for uranium mineralisation. The close association of uranium and metallic sulphide mineralisation with microstructural, mineralogical (albitisation, chloritisation, and microclinisation), and geochemical variations can be applied as suitable exploration guides in a similar geological set-up worldwide. Full article

Mining and mineral processing industry adversely affects ecosystems and communities in nearby areas, including high freshwater consumption and scarcity. That is why the emerging global trend is to use sea water in flotation to recover valuable minerals from finely disseminated base metals ores. Recent studies investigate sea water flotation of copper, molybdenum, nickel sulphides and pyrite, while flotation of sphalerite, the main valuable mineral for zinc production, remains uncovered. This paper examines the feasibility of sphalerite flotation by conventional collectors in artificial sea water using a bubble-particles technique and frothless flotation tests. Potassium isopropyl xanthate (PIPX) and sodium isopropyl dithiophosphate (SIDTP) were used as collectors, and copper sulphate was introduced as the activator, while zinc sulphate and sodium sulphide were used as depressants. We examined the most common size fractions of sphalerite: medium (−74 + 44 μm) and fines (−44 μm). The findings showed the feasibility of sphalerite flotation in artificial sea water. We also established correlations between the rate of bubble-particle attachment and the sphalerite flotation recovery resulting in the growth of flotation recovery with the increase of the bubble-particle attachment rate. The results can be used as guidelines in choosing flotation reagents for sphalerite flotation in sea water. Another practical application of the results is the potential for sustainable development of the industrial sector, ecosystems and societies due to the replacement of fresh water by sea water, although further technological and environmental studies are required. Full article

The wreck of the Punic ship exhibited at the Archaeological Park of Lilybaeum (Marsala, Italy) is a unique example in the world. In this paper, the investigation of some metal finds (30 nails and 3 fragments of sheathings) belonging to the wreck of the Punic ship is reported. Portable X-ray fluorescence and Raman spectroscopy allowed us to identify the elements and compounds constituting them and make some deductions about their composition. X-ray diffractometry, polarised optical microscopy and scanning electron microscopy of the collected micro-samples allowed us to explain the degradation that occurred in the underwater environment. Full article