Sulfide Complex Research Articles

Hydrometallurgical Recovery of Cu and Zn from a Complex Sulfide Mineral by Fe3+/H2SO4 Leaching in the Presence of Carbon-Based Materials

Chalcopyrite, the main ore of copper, is refractory in sulfuric media with slow dissolution. The most commonly employed hydrometallurgical process for the oxidation of chalcopyrite and copper extraction is the sulfuric acid ferric sulfate system The main objective of the present work is to study the use of cheap carbon-based materials in the leaching of copper and zinc from a sulfide complex mineral from Iberian Pyrite Belt (IPB). The addition effect of commercial charcoal (VC) and two magnetic biochars (BM and HM) that were obtained by pyrolysis of biomass wastes was compared to that of commercial activated carbon (AC). The experimental results performed in this work have shown that the presence of carbon-based materials significantly influences the kinetics of chalcopyrite leaching in the sulfuric acid ferric sulfate media at 90 °C. The amount of copper and zinc extracted from IPB without the addition of carbon-based material was 63 and 72%, respectively. The highest amount of extracted zinc (>90%) was obtained with the addition of VC and AC in IPB/carbon-based material ratio of 1/0.25 w/w. Moreover, it is possible to recover more than 80% of copper with the addition of VC in a ratio 1/0.25 w/w. Moreover, an optimization of the properties of the carbon-based material for its potential application as catalyst in the leaching of metals from sulfide is necessary.

Acquirement of Gold from Concentrate (Pezinok, Slovakia) with Utilization of Algae in Mechanochemical Processes

The deficiency of primary raw materials and the difficult processing of sulphide concentrates with low gold content, as well as the long-time use of the dangerous cyanide method, instigated to the search a more effective and environmentally conscious method of acquirement this noble metal. For this reason, this work was focused on gold obtaining from a refractory sulphide complex concentrate (Pezinok, Slovakia) with the application of the non-cyanide mechanochemico-biological process. Gold in this complex concentrate occurs physically enclosed in the intercrystalline space of sulphide minerals, and is also isomorphic and fills structure defects in sulphides. The exclusion of gold from such complex mineral matrices of the concentrate can be achieved by using a mechanochemico-biological process. This innovative process makes possible obtaining of gold using an application of a thiourea solution, which is a convenient alternative opposite to the toxic cyanidation method. The utilized of the biological process with the application of algae has shown that algae with siliceous structures make it possible to obtain of gold from a complex concentrate (Pezinok, Slovakia) with dimension in the nano range. These algae are part of aquatic ecosystems and, in addition, are being food for other animals, utilizing for fuel production and, more recently, they are the important raw material for the production of hydrogen, methane and some types of biofuels. Limnetic algae (diatoms, golden algae) have unique properties, they create the largest mass of biomass of all plants on Earth and at the same time they are able to move. The mechanochemico-biological process is a method that enables to obtain gold nanoparticles 100 nm from the refractory sulphide concentrate (Pezinok, Slovakia). Mechanochemical activation of this concentrate and silica shells of the limnetic algae of tribes (Dinobryon, Surirella) in thiourea solution caused changes in physico-chemical properties of the minerals of gold as well as in the constituents of the algae minerals. These structural changes had under specific conditions a decisive influence on the exclusion of gold nanoparticles to the thiourea solution. The gold nanoparticles had subsequently fixed in the cellular matrix on mechanochemical activated algae shells. The reason for the fixation of gold nanoparticles was the action of biomolecules that algal cells during activation secreted while they defend again the chemical effect of metal ions present in the solution. Nanoparticles of gold were acquirement from the concentrate after less than two hours by described mechanochemico-biological process. In the case of mechanochemical activation of the concentrate, but without the activation of defined algae, the exclusion of gold nanoparticles was not confirmed even after a triple activation time (six hours). Owing to, the algae had to be activated to recover of gold from this sulphide concentrate. It follows, the entire mechanochemico-biological process had to be followed.

Evolution of Sulfides in Nonoriented Silicon Steels during Heating Process

The evolution of sulfides in nonoriented silicon steels during the heating process is investigated through chemical composition analysis and thermodynamic calculation. Evolution behaviors of sulfides are analyzed using field emission scanning electron microscope (FESEM) and automatic scanning electron microscope (ASPEX). A homogeneous complex sulfide is detected containing magnesium and manganese. The different proportions of MgS and MnS in the complex sulfide are due to the competition between Mg, Mn, and S in low‐sulfur steel. Sulfides and compounds containing sulfides, oxides, and nitrides are mainly formed during the heating temperature of 1000 °C. The presence of sulfides and compounds with sulfide and oxide is at the temperature of 1300 °C. Sulfides reach equilibrium in less time than AlN at 1000 °C, while the time for sulfides to reach the theoretical equilibrium value takes precedence over oxides at 1300 °C. In addition, the proportions of various types of precipitation at 1300 and 1000 °C are discussed through the theoretical calculation and the observation results.

Inexpensive Organic Materials and Their Applications towards Heavy Metal Attenuation in Waters from Southern Peru

There is interest in using locally available, low cost organic materials to attenuate heavy metals such as Cd, Cr, Cu, Hg, Ni, Pb, and Zn found in surface waters in Peru and other developing regions. Here we mesh Spanish language publications, archived theses, and prior globally available literature to provide a tabulated synthesis of organic materials that hold promise for this application in the developing world. In total, nearly 200 materials were grouped into source categories such as algae and seashells, bacteria and fungi, terrestrial plant-derived materials, and other agricultural and processing materials. This curation was complemented by an assessment of removal potential that can serve as a resource for future studies. We also identified a subset of Peruvian materials that hold particular promise for further investigation, including seashell-based mixed media, fungal blends, lignocellulose-based substrates including sawdust, corn and rice husks, and food residuals including peels from potatoes and avocadoes. Many studies reported percent removal and/or lacked consistent protocols for solid to liquid ratios and defined aqueous concentrations, which limits direct application. However, they hold value as an initial screening methodology informed by local knowledge and insights that could enable adoption for agriculture and other non-potable water reuse applications. While underlying removal mechanisms were presumed to rely on sorptive processes, this should be confirmed in promising materials with subsequent experimentation to quantify active sites and capacities by generating sorption isotherms with a focus on environmental conditions and specific contaminated water properties (pH, temperature, ionic strength, etc.). These organics also hold promise for the pairing of sorption to indirect microbial respiratory processes such as biogenic sulfide complexation. Conversely, there is a need to quantify unwanted contaminant release that could include soluble organic matter and nutrients. In addition to local availability and treatment efficacy, social, technical, economic, and environmental applicability of those materials for large-scale application must be considered to further refine material selection.

Bioleaching of Cu and Zn from Complex Sulfide using an Isolated Iron Oxidizing Bacteria

Bioleaching kinetics of copper and zinc from a complex sulfide concentrate sample was evaluated in this manuscript. An acidophilic microorganism was used for the metal dissolution. The metal dissolution was evaluated based on the variation of leaching parameters like initial pH, pulp density, and initial ferrous concentration. The leaching rate of metals increased with the increase of initial ferrous concentration up to 20g/L, and it decreased on a further increase of the initial ferrous concentration. It decreased at the initial ferrous concentration above 20g/L due to the formation of an iron precipitate, which did not allow the contact of lixiviant with the metal sulfide matrix. The leaching rate increased with the increase of initial pH up to 2.0, and thereafter it decreased. Similarly, the leaching rate remained unchanged up to pulp density of 15%(w/v), and it decreased upon further increase of the pulp density due to the mutual completion of the complex sulfide particles towards the lixiviants.

Effect of adding yttrium on precipitation behaviors of inclusions in E690 ultra high strength offshore platform steel

AbstractThe mechanism of inclusions precipitation of the E690 offshore platform steel, with and without addition of yttrium, was studied using the thermodynamic calculation method. The results show that in the E690 steel in the absence of yttrium, the MnS inclusions were precipitated in the liquid phase at the solidification front. By adding the yttrium, MnS inclusions were replaced by spindle and spherical yttrium-containing oxide and sulfide complex inclusions, and the precipitation sequence of yttrium-containing inclusions in the liquid steel was Y2O3, Y2O2S, and YS. However, Y2S3 inclusions cannot be precipitated in the liquid steel under the experimental conditions. It was also found that Al2O3 inclusions can be formed in the liquid steel with and without addition of yttrium. The thermodynamic calculation results are in accordance with the experimental results.

Base metal citrate pretreatment of complex ores to improve gold and silver leaching with thiourea

A pretreatment to remove and recover base metals present in complex sulfide refractory ores is proposed as a method to improve the extraction of precious metals with thiourea. Sodium citrate solutions at pH 8 and 5 were employed to extract lead and iron, respectively, from two concentrates: one having silver in a primarily galena matrix and the other, with gold associated with pyrite. The pretreatment solutions, containing the base metals, were subjected to electrolysis and pH adjustment, before being recycled back to the pretreatment stage. The results showed that citrate pretreatment successfully extracted lead and some iron, liberating the precious metals for thiourea leaching. The citrate pretreatment solution could be reutilized, after base metal removal, decreasing the reagent and water requirements. In all cases, the citrate pretreatment improved precious metal extraction.

C-N, C-S and S-S Bond Cleavage by Rhodium PCcarbene P Pincer Complexes.

Rhodium PCcarbene P complexes 1-L {L=PPh3 , PPh2 (C6 F5 )} react with isothiocyanate, carbodiimide and disulphide to enable C-S, C-N and S-S bond cleavage. The cleaved molecules are sequestered by the metal center and the pincer alkylidene linkage, forming η2 -coordinated sulfide or imide centered pincer complexes. When a C-S or S-S bond is cleaved, the resulting complexes can bridge two rhodium centers through sulphur forming dimeric complexes and eliminating a monodentate phosphine ligand.

Chalcopyrite leaching in acid media: a review

In the modern practice of copper production, more and more attention is paid to the possibility of treating low-percentage sulfide ores that cannot be treated with conventional procedures (crushing, grinding, flotation). In addition to this, the processes of obtaining copper from complex sulfide concentrates, which cannot undergo pyrometallurgical processing, are increasingly being investigated. Extraction of copper from such raw materials is in most cases achieved by applying leaching procedures.
 Since chalcopyrite (CuFeS2) is by far the most abundant copper sulfide mineral, a large portion of the research is focused on studying the behavior of chalcopyrite in the leaching process, because processes of copper extraction from increasingly poor raw materials may be created using results of these studies. In addition, the main objective of this research is examining the kinetics and mechanism of chalcopyrite oxidation under the influence of various oxidants (O2, Fe3 +, H2O2, chlorate ions, etc.) and at the same time obtaining data necessary for the development of copper production process that could satisfy increasingly stringent technological, economic and environmental criteria.
 The paper presents the existing knowledge of the chalcopyrite leaching procedure and phenomena that accompany chalcopyrite oxidation in acidic sulfate and chloride solutions.

Synthesis, characterization and electrochemical investigation of physical vapor deposited barium sulphide doped iron sulphide dithiocarbamate thin films

Current work has undertaken the synthesis of barium sulphide, ferrous sulphide and barium sulphide doped ferrous sulphide complex using dithiocarbamate (DTC) ligand as single source precursor for the first time in an in-situ mode. Doped metal sulphides were grown into thin films of 840 nm thickness via physical vapor deposition (PVD) on pre-sonicated fluorine doped tin oxide (FTO) inside resistive heating unit (RHU). Prepared metal sulphides and thin films were evaluated for their crystallographic, compositional, optical, microstructural and elemental analysis via X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet visible spectrophotometry (UV-Vis), field emission scanning electron microscopy (FE-SEM), and Rutherford back scattering spectrometry (RBS), respectively. An average crystallite size of 37 nm was exhibited by XRD. FT-IR peaks recorded in the range of 4000–400 cm−1 via potassium bromide palletization technique were indicative of the successful chelation of metal sulphides by DTC. UV-Vis based optical parameters expressed a direct and indirect bandgap of 3.5 and 3 eV, respectively. Exceedingly compact and uniform thin films were exhibited by FE-SEM with development of agglomerated clusters. Strong signals for barium, iron and sulphur were confirmed via RBS having 5 MV pelletron tandom accelerator with an alpha beam of 2.08 MeV made normally incident on the target sample and scattered at an angle of 170°. Electrochemical investigation i.e. cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry (CA) of the fabricated thin films expressed impressive electrical characteristics with a specific capacitance of 34.06 Fg−1 at 10 mV/s and a functional stability for 1900 s at 100 mA. Fabricated films possess a suitable candidacy for utilization in photovoltaic and electrochemical contraptions.

Currents and topography drive assemblage distribution on an active hydrothermal edifice

The deep sea is characterized by a wide range of landscapes, including complex features where topography and currents interact to form highly heterogeneous habitats. In addition to a complex topography, hydrothermal vent environments are characterized by strong environmental gradients that structure the spatial distribution of biological communities. The role of vent fluid temperature and chemical composition on species distribution is now well understood, but investigations on the effects of the complex sulfide edifice topography are scarce. Here, we used a novel approach combining 3D photogrammetric reconstruction, in situ environmental measurements and modeling to characterize assemblage distribution on the active edifice Eiffel Tower (Lucky Strike, Mid-Atlantic Ridge). Through the analysis of a high-resolution 3D model of the edifice, we show that assemblage distribution along with hydrothermal activity vary with their position on the edifice. Although physical terrain variables had a minor effect on assemblage distribution, the distance from fluid exits explained the distribution of most assemblages. However, these particular variables did not significantly explain the distribution of medium-sized Bathymodiolus azoricus mussels, the dominant assemblage on the edifice. Similarly, proximity to fluid exits only partially accounted for the distribution of microbial mats throughout the edifice. By modeling the current-driven dispersion of hydrothermal plumes around the edifice, we demonstrated that differences in mussel sizes may be due to differences in exposure time to currents bringing plume material. For the first time, we provide evidence that hydrothermal plumes can affect faunal assemblages meters away from fluid exits and that this relatively long-distance effect of vent plumes can fully account for microbial mat distribution throughout the edifice. Our findings extend the area of influence of hydrothermal plumes on vent communities considerably beyond previous estimations and suggest that the interactions between bottom currents, topography and smoker locations should be further investigated and considered as important structuring factors at vents. This novel approach, allowing to cover large areas of the seafloor, is particularly well suited for deep environments where topography and currents interact to form complex oceanographic patterns (e.g. canyons, seamounts). Its application to larger areas and various ecosystems can significantly enhance our understanding of benthic communities’ distribution at large.

Biogeochemical cycling of heavy metals in lake sediments: impact of multispecies diffusion and electrostatic effects

Fate and transport of heavy metals is controlled by the biogeochemical processes in the environment. Reactive transport modeling is particularly important for capturing the complex interplay between the microbial community dynamics and redox-stratified environments. The focus of this study is to investigate the impacts of (i) multicomponent diffusion (MCD) and (ii) electrical double layer (EDL) on reactive diffusive transport of heavy metals at Lake Coeur d’Alene (LCdA) sediments. The solute benthic fluxes at LCdA sediments are controlled by diffusion, and therefore, the biogeochemical model is focused purely on diffusive transport. In diffusive transport-dominated multicomponent systems, species-specific multicomponent diffusion (i.e., Nernst-Planck representation of diffusion) and the explicit treatment of electrostatic effects can play an important role on the overall dynamics of biogeochemical cycling of metals in the system. The results of this study demonstrate that the use of single uniform diffusion coefficient for all species in purely diffusion-dominated sediments may underestimate the mobility of heavy metals undergoing complex reaction network. This outcome is further signified when explicit treatment of EDL effects is considered in addition to MCD. The simulation results also illustrate the importance of aqueous metal (bi)sulfide complexes, especially when MCD and EDL effects are implemented in reactive transport simulations, impacting the solubility and dynamics of heavy metals in diffusion-dominated systems. The competitive effects of Fe-reducing bacteria FRB and sulfate reducing bacteria SRB activities on pH and overall biogeochemical processes are also demonstrated with multispecies diffusion and explicit treatment of electrostatic effects in the system.

High‐temperature phase and microstructure evolution of polymer‐derived SiZrCN and SiZrBCN ceramic nanocomposites

ABSTRACTA zirconium and a zirconium/boron containing single‐source precursor were synthesized via chemical modification of a commercially available polysilazane (Durazane 1800) with tetrakis (dimethylamido) zirconium (IV) (TDMAZ) as well as with both TDMAZ and borane dimethyl sulfide complex, respectively. The polymer‐to‐ceramic transformation of the precursors into SiZrCN and SiZrBCN ceramics as well as the thermal evolution of their phase composition and microstructure was studied. The pyrolysis of the precursors led to the formation of amorphous SiZrCN and SiZrBCN ceramics. Interestingly, the as prepared SiZrBCN ceramic was single‐phasic and fully featureless; whereas SiZrCN exhibited the presence of nano‐sized ZrO2 particles; however, only very localized in close proximity to internal surfaces. Heat treatment at higher temperatures induced crystallization processes in both prepared ceramics. Thus, at temperatures beyond 1500°C, cubic ZrCxNy, β‐Si3N4 as well as β‐SiC were generated. It was shown that the incorporation of B into SiZrCN suppressed the crystallization of ZrCxNy and, in addition, impeded the reaction of SiNx with C, resulting in an improved thermal stability of SiZrBCN compared to SiZrCN ceramic. Moreover boron was shown to be mainly located in the sp2‐hybridized “free” carbon present in SiZrBCN, forming a turbostratic BCN phase which has been unequivocally detected by means of high‐resolution transmission electron microscopy (HRTEM) and energy‐dispersive X‐ray spectroscopy (EDS).

Depression of lead-activated sphalerite by pyrite via galvanic interactions: Implications to the selective flotation of complex sulfide ores

Complex sulfide ores are typically mixtures of various sulfide minerals like sphalerite (ZnS), chalcopyrite (CuFeS2), galena (PbS), pyrite (FeS2), and barite (BaSO4) and processed by selective flotation to recover target-sulfide minerals like chalcopyrite and sphalerite. Some complex sulfide ores, however, contain anglesite (PbSO4), a mineral with relatively high solubility, that complicates selective flotation because its dissolution releases Pb2+, which ‘activates’ co-existing sulfide minerals (e.g., ZnS). Because both target and non-target sulfide minerals are recovered when flotation is non-selective, another flotation stage to recover target minerals in froth products is required. Aside from anglesite, co-existing gangue sulfide minerals like pyrite also complicate selective flotation because of their strong effects on the floatability of target-sulfide minerals via electrochemical interactions.In this study, the effects of pyrite on the floatability of lead-activated sphalerite were investigated using flotation tests and electrochemical techniques coupled with contact angle measurements. Moreover, factors important to lead-activated sphalerite floatability were elucidated in detail using dissolution experiments and X-ray photoelectron spectroscopy (XPS). Finally, a mechanism for lead-activated sphalerite depression by pyrite is proposed.

An affordable method to produce CuInS2 ‘mechano-targets’ for film deposition

We report on the room temperature, simple and cheap preparation by mechano-synthesis of polycrystalline targets of complex sulphide semiconductors, namely CuInS2 (CIS), to be used for film deposition in physical vacuum techniques such as PLD, sputtering or LT-PED. The sulphur (S)-based targets usually require expensive high pressure equipment to compensate the high S vapour pressure; nevertheless they are indispensable for the deposition of high band-gap semiconductor materials. The comparison of CIS films grown by mechano-synthesis and by commercial targets demonstrates similar material quality, making the mechano-synthesis a viable solution in the fabrication of high band-gap, S-based targets of complex chalcogenides.

Reduction of Amides and Esters with Borane Dimethyl Sulfide Complex

Reduction of Amides and Esters with Borane Dimethyl Sulfide Complex

ABOUT MODERN RESEARCH IN THE FIELD OF COMPLEX SULFIDE COMPOUNDS (STATE AND TRENDS)

The article provides an overview of the most significant scientific papers (from more than 600literature sources), devoted to the studies of complex sulfides, some of which are given in this research. There areexamples of research in the field of the most promising complex sulfides CdZnS, AgInS, CuInS, ZnInS and thepredicted scope of their practical application in the article. The tendencies in the research for physicochemicalproperties of complex metal sulphides are revealed

Petrography and Mineralogy of the Quartz and Quartz-Feldspar Sulphide Veins in the Pan-African Syenitic Massif of Guider (North Cameroon)

In the syenitic pluton of Guider (593 ± 4 Ma) in the North-West Cameroon domain of Central African Fold Belt, mineralized N-S to NE-SW vertical or sub-vertical quartz and quartz feldspar veins has been recently identified. In this contribution, we present petrography and mineralogy of these veins, in order to constrain their genesis and emplacement mechanisms based on detailed field work, petrographic studies and chemical characterization of minerals by using an electron probe microanalyser (EPMA). Field observations and vein microstructures show that the emplacement of the veins has been controlled by the dextral N-S trending strike-slip shear zones related to the regional D2 deformation phase. The results of mineralogical analysis reveal the co-presence of silicates and metallic minerals that include magnetite, ilmenite, pyrite, bismuthite, galena (very rare) and sulphide complexes (BiPbS, BiAgPbS, FeBiPbCuS, BiFe(TeS), FeBiPbS, BiPbCuS). The gangue is represented by quartz (quartz 1, quartz 2 and quartz 3), feldspars, sericite, chlorite, yellowish brown clay minerals, and hematite. The textural relationships between sulphides, quartz and alteration products show that the mineralization is essentially syn- to late-D2 and suggest that syenitic country rock and dextral shear zones have played an important role in the metallogenesis of these veins. This mineralization shows characteristics for copper-bearing calc-alkaline deposits, but differs from these by its more extensive alteration and its abundance in hematite. Substitutions of Al(IV) by Si(IV) in sericite associated with the sulphide mineralization and cataclastic deformation suggest that the temperature of trapping of the fluids is between 230°C and 275°C.

FAST DETERMINATION OF THE SULFUR SPECIES IN SOLID PHASE SYSTEMS BY A TPO-IR METHOD

Qualitative and quantitative assessment of total sulfur and sulfur species in solid phase is necessarily important for development of effective desulfurization methods, reduction of environmental pollution, and prevention of catalyst poisoned. In this work, TPO-IR (Temperature Programmed Oxidation- Infrared) method was used for rapid determination of sulfur species in solid minerals. The high purity of Ag2S was used as the calibration materials at the fixed temperature of 1100 °C, and the TPO experimental runs were performed on the solid minerals of phosphorite and coal. The results show that pyrite sulfur with Tmax of 426 °C, and two thiophene sulfurs with Tmax of 450 °C and 481 °C were found in Kaiyang phosphorite by fitting the TPO-IR curves; while pyrite sulfur with Tmax of 432 °C, complex sulfide with Tmax of 679 °C and sulfate sulfur with Tmax of 939 °C were found in Weng’an phosphorite. For Gas coal, the TPO-IR curves of sulfur release can be deconvoluted into seven individual curves, while that of Anthracite deconvoluted into four individual curves. In conclusion, the TPO-IR method has many advantages for determination of sulfur species in solid phase systems, such as less sample consumption, simple pretreatment, convenient operation and low cost, etc.

Optimization of chlorite and talc flotation using experimental design methodology: Case study of the MCG plant, Morocco

SYNOPSIS Response surface methodology (RSM), central composite design (CCD), and desirability functions were used for modelling and optimization of the operating factors in chlorite and talc (collectively termed 'mica') flotation. The influence of pulp pH, cyanide (NaCN) consumption, and particle size was studied with the aim of optimizing ssilicate flotation while minimizing recoveries of galena, chalcopyrite, and sphalerite. Flotation tests were carried out on a representative sample of a complex sulphide ore from Draa Sfar mine (Morocco). The model predictions for the flotation of each of the minerals concerned were found to be in good agreement with experimental values, with R2 values of 0.91, 0.98, 0.99, and 0.90 for mica, galena, chalcopyrite, and sphalerite recoveries, respectively. RSM combined with desirability functions and CCD was successfully applied for the modelling of mica flotation, considering simultaneously the four flotation responses to achieve the maximum recovery of mica and minimal loss of Pb, Cu, and Zn to the flotation concentrate. Keywords: chlorite, talc, flotation, response surface methodology, central composite design, optimization.