Metal Grades Research Articles

The Effect of the Use of Technological Lubricants Based on Vegetable Oils on the Process of Titanium Sheet Metal Forming

Abstract The paper evaluates the drawability of titanium sheet metal Grade 2, with the focus on friction conditions that are present in the sheet metal forming process. The study aims to present the results of the examinations of the friction coefficient during a strip drawing test. The focus of the experiment was on lubricants based on vegetable oils i.e. rapeseed oil, sunflower oil and olive oil. Boric acid was used to improve the lubricating properties of vegetable oils. The results of numerical simulations of the process of forming a cover with stiffening components made of grade 2 titanium sheet metal was also presented. The numerical simulation was carried out using the FEM method with PAMStamp 2G software. The effect of conditions of friction between the sheet metal and tool parts and pressure force of the blank holder on the forming process were investigated. Numerical calculations were performed with consideration for the phenomenon of material strain hardening and anisotropy of plastic properties of the sheet metal formed. The analysis of the deformations and reduction in wall thickness of the drawn parts can be used for determination of the effect of changes in selected parameters on the process of drawn part forming. The quality of drawn parts was assessed based on the shape inaccuracy determined during simulation of forming. The inaccuracy depended on the conditions of the process and strength properties of the titanium sheet metal.

Free vibration analysis of functionally graded beams resting on variable elastic foundations using a generalized power-law distribution and GDQ method

In this research work, based on the Euler–Bernoulli theory and by means of Generalized Differential Quadrature (GDQ) method, free vibration characteristics of functionally graded (FG) beams resting on two-parameter foundation are focused. The two-constituent functionally graded beam consists of ceramic and metal grading through the thickness. A generalized power-law distribution is considered for the ceramic volume fraction. A detailed parametric study is carried out to highlight the influences of different profiles of fiber volume fraction, four parameters of power-law distribution and two-parameter elastic foundation modulus on the vibration characteristics of the FG beams.

Numerical Investigation of Caved Rock Mass Friction and Fragmentation Change Influence on Gravity Flow Formation in Sublevel Caving

Metal grade dilution is the main production disadvantage of the sublevel caving method, and overcoming this problem has been investigated over the years using different methodologies. Herein, numerical simulation using the discrete element method is used to analyze the influence of friction and fragmentation change in caved rock mass on ore dilution and recovery. The individual and mutual change of each parameter is analyzed. It is considered that at the beginning, the friction angle can be lower or higher than the basic friction angle, and after a certain moment, it will come close to the basic friction value, while fragmentation always decreases. The results showed that both friction and fragmentation, when decreasing, are influencing the higher dilution due to smaller kinematic resistance in the caved mass. If lower friction than the basic one is considered, with the drop of fragmentation, the decrease of dilution occurs. Once the basic friction angle is reached, the fragmentation of the caved mass becomes the dominant influencing factor, and its decrease will continuously increase the dilution until the end of production. However, identifying periods when these changes occur, the possibility for better production planning opens at the design stage, as well as the application of different sublevel designs.

Metallurgical Study of Stellite 6 Cladding on 309-16L Stainless Steel

309-16L stainless steel was deposited over base metal Grade 91 steel (9Cr–1Mo) as buffer layer by shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW) and flux cored arc welding processes, and then, Stellite 6 (Co–Cr alloy) was coated on stainless steel buffer by SMAW, GTAW and plasma transferred arc welding processes. Stellite 6 coatings were characterized using optical microscope, Vickers hardness tester and optical emission spectrometer, respectively. The FCA deposit has less heat-affected zone and uniform hardness than SMA and GTA deposits. The buffer layer has reduced the formation of any surface cracks and delamination near the fusion zones. The microstructure of Stellite 6 consists of dendrites of Co solid solution and carbides secretion in the interdendrites of Co and Cr matrix. Electron-dispersive spectroscopy line scan has been conducted to analyse the impact of alloying elements in the fusion line and Stellite 6 deposits. It was observed that dilution of Fe in PTA-deposited Stellite 6 was lesser than SMA and GTA deposits and uniform hardness of 600–650 \(\hbox {HV}_{0.3}\) was obtained from PTA deposit. The chemical analysis resulted in alloy composition of PTA deposit has nominal percentage in comparison with consumable composition while GTA and SMA deposits has high dilution of Fe and Ni.

Rare earths (La, Ce, Nd) and rare metals (Sn, Nb, W) as by-products of kaolin production – Part 2: Gravity processing of micaceous residues

This paper, which is the second in a series of three, follows a previous study that showed that Light Rare Earth Elements (LREE), hosted in monazite and rare-metals (Sn, Nb, W), hosted in cassiterite, rutile and wolframite, respectively, are pre-concentrated in the micaceous residue of a kaolin plant. However, the low grade and fine size range of the metal-bearing minerals make their recovery difficult using unique gravity concentration methods. An enhanced gravity concentration flowsheet was tested, which began by screening the residue into three size fractions: +180μm, 180–53μm and −53μm. The 180–53μm fraction was treated with a spiral as a roughing unit and then a shaking table as a cleaning unit, whereas the fine −53μm processing is addressed in the third publication. The design of experiments (DOE) methodology was used to set the best operating parameters. The best heavy mineral recoveries for the spiral concentrate were obtained at a low wash water flow rate and low pulp density. The spiral scavenging tests showed that up to 80% of the heavy minerals can be recovered. However, the mineralogical analysis showed that after three passes, middlings began to be recovered, suggesting that the scavenging operations should not be further continued. Furthermore, up to 70% monazite could be recovered in a single pass. Shaking table testing on the spiral concentrates showed that heavy mineral concentrates with up to 98.5% of heavy minerals can be recovered. However, the concentrate grades were still low for most metals (Sn, Nb and W), with the exception of LREEs, which reached up to 1.6% LREE in the shaking table concentrate. Given the reasonable overall recoveries, the main reason for the low concentrate grades could have been the very low grade of the feed material, which was two to three times less enriched in metals than the average micaceous residues grades. This suggests that the cut-off grade for those metals should be above 100ppm and points to the critical aspect of metal grade variability in the micaceous residue as a major issue if potential industrial applications are to be considered.

Study on recovery of valuable metals from waste mobile phone PCB particles using liquid-solid fluidization technique

In this paper, an effort was made to separate the valuable metals from waste mobile phone printed circuit board (PCB) particles using liquid-solid fluidization technique. Based on the mechanical liberation characteristics of waste mobile phone PCBs, four closely sieved particles having a granularity, respectively, of 0.075–0.106, 0.106–0.18, 0.18–0.25 and 0.25–0.35mm were chemically analyzed and charged into the fluidized bed to study the fluidization separation behavior. The minimum fluidization velocities and terminal settling velocities of single components were served as an important tool for the evaluations of the experimental data. The results showed that, in the process configuration, the fluidization separation was effective within each limited range of particle size with proper control on water velocity. When the water velocity was in the appropriate range, higher metal yield and grade could be obtained. The calculated minimum fluidization velocities and terminal settling velocities of waste mobile phone PCB particles were in reasonable agreement with the actual operating water velocities. Additionally, the influence of the porosity of perforated plate distributor and the height of the fluidized bed on the metal grade and yield was also discussed. The application of liquid-solid fluidization technique in beneficiation of waste mobile phone PCB particles is expected to be one of the important developmental directions.

A multivariate destination policy for geometallurgical variables in mineral value chains using coalition-formation clustering

Complex polymetallic mining projects with multiple processing streams tend to require tight blending constraints, with different operational and processing targets. These blending requirements are generally not focused solely on metal grade, but rather on a set of geometallurgical variables that affect the performance of the operation and its ability to meet targets and maximize project value. Because of this, a multivariate destination policy is developed here, based on coalition formation clustering (a line of study of cooperative game theory), which avoids the use of cut-off grades and defines where material is sent by accounting for the value and relation of groups of blocks being processed together. This allows improving investment decisions as a result of optimizing project performance, because the variables that affect blending and processing requirements are actively accounted for in the optimization process. A case study on a copper-gold mine with six destinations is presented, where the method proposed shows significant improvements in meeting processing requirements and increases the expected net present value by 5.6% when compared to a traditional method. This shows that complex processing requirements can be accounted for and respected without any loss of project value.

Spatial Pair-Copula Modeling of Grade in Ore Bodies: A Case Study

A real-world mining application of pair-copulas is presented to model the spatial distribution of metal grade in an ore body. Inaccurate estimation of metal grade in an ore reserve can lead to failure of a mining project. Conventional kriged models are the most commonly used models for estimating grade and other spatial variables. However, kriged models use the variogram or covariance function, which produces a single average value to represent the spatial dependence for a given distance. Kriged models also assume linear spatial dependence. In the application, spatial pair-copulas are used to appropriately model the non-linear spatial dependence present in the data. The spatial pair-copula model is adopted over other copula-based spatial models since it is better able to capture complex spatial dependence structures. The performance of the pair-copula model is shown to be favorable compared to a conventional lognormal kriged model.

Spent battery flows, characterization and recycling processes

Spent batteries are an important waste flow regarding the recovery of the contained metals motivated by economic, environmental and strategic reasons. The portable battery market is dominated by primary Zn-Mn cells, but the market of secondary batteries are continuously growing, with particular relevance for Li-ion batteries, used in practically all electronic devices. The batteries are metal concentrates, having metal grades such as 20%–30% of Zn, Mn, Co, Ni, depending on the battery system. These metals are specifically concentrated in the electrodes, which are the most important component of a battery. The most usual chemical forms of these metals in the electrodes are oxides or hydrated oxides, but other solid phases can be found such as metal alloys. The recycling of batteries can be done by pyrometallurgical and hydrometallurgical processes. The first one usually involves the distillation of some more volatile metals, such as Zn in Zn-Mn cells and Cd in Ni-Cd cells. For Ni-MH and Li-ion batteries, some pyrometallurgical approaches involve the melting and recovery of Ni or Co, but with losses of other metals (like lithium and rare earths). The hydrometallurgical alternative allows higher metal recovery rates, as practised industrially for Zn-Mn and Li-ion batteries. Many studies on alternative processes for recycling Li-ion batteries have been intensively carried out due to the special interest on these batteries nowadays and in the future.

The Xitieshan volcanic sediment-hosted massive sulfide deposit, North Qaidam, China: Geology, structural deformation and geochronology

The Xitieshan deposit (~64Mt at 4.86% Zn, 4.16% Pb, 58g/t Ag, and 0.68g/t Au) is hosted by the Middle to Late Ordovician Tanjianshan Group of the North Qaidam tectonic metallogenic belt, NW China. This belt is characterized by island arc volcanic, ultra-high pressure (UHP) metamorphic and ophiolitic rocks. The Tanjianshan Group constitutes a succession of metamorphosed bimodal volcanic and sedimentary rocks, which are interpreted to have formed on the margin of a back-arc ocean basin between the Qaidam block and the Qilian block.Four stratigraphic units are identified within the Ordovician Tanjianshan Group. From northeast to southwest they are: 1) unit a, or the lower volcanic-sedimentary rocks, comprising bimodal volcanic rocks (unit a-1) and sedimentary rocks (unit a-2) ranging from carbonates to black carbonaceous schist; 2) unit b, or intermediate-mafic volcaniclastic rocks, characterized by intermediate to mafic volcaniclastic rocks intercalated with lamellar carbonaceous schist and minor marble lenses; 3) unit c, a purplish red sandy conglomerate that unconformably overlies unit b, representing the product of the foreland basin sedimentation during the Early Silurian; 4) unit d, or mafic volcanic rocks, from base to up, comprising the lower mafic volcaniclastic rocks (unit d-1), middle clastic sedimentary rocks (unit d-2), upper mafic volcaniclastic rocks (unit d-3), and uppermost mafic volcanic rocks (unit d-4). Unit a-2 hosts most of the massive sulfides whereas unit b contains subordinate amounts.The massive stratiform lenses constitute most of the Xitieshan deposit with significant amount of semi-massive and irregularly-shaped sulfides and minor amounts in stringer veins. Pyrite, galena and sphalerite are the dominant sulfide minerals, with subordinate pyrrhotite and chalcopyrite. Quartz is a dominant gangue mineral. Sericite, quartz, chlorite, and carbonate alteration of host rocks accompanies the mineralization.U-Pb zircon geochronology yields three ages of 454Ma, 452Ma and 451Ma for the footwall felsic volcanic rocks in unit a-1, sedimentary host rocks in unit a-2 and hanging-wall unit b, respectively. The Xitieshan deposit is considered to be coeval with the sedimentation of unit a-2 and unit b of the Tanjianshan Group. The Xitieshan deposit has been intensely deformed during two phases (main ductile shear and minor ductile-brittle deformation). The main ductile shear deformation controls the general strike of the ore zones, whereas minor deformation controls the internal geometry of the ore bodies. 40Ar-39Ar age of muscovite from mylonitized granitic gneisses in the ductile shear zone is ~399Ma, which is interpreted to date the Xitieshan ductile shear zone, suggesting that Early Devonian metamorphism and deformation post-dated the Tanjianshan Group.The Xitieshan deposit has many features similar to that of the Bathurst district of Canada, the Iberian Pyrite Belt of Spain, the Wolverine volcanogenic massive sulfide deposit in Canada. Based on its tectonic setting, host-rock types, local geologic setting, metal grades, geochronology, temperatures and salinities of mineralizing fluid and source of sulfur, the Xitieshan deposit has features similar to sedimentary exhalative (SEDEX) and VMS deposits and is similar to volcanic and sediment-hosted massive sulfide (VSHMS) deposits.

Mathematical analysis of the gas–solid fluidized bed separation of metals and nonmetals from waste PCB powders

Modern society is generating increasing quantities of waste printed circuit boards (PCBs). Together with the complicated components of high values, the treatment of waste PCBs has been a heavily researched and difficult topic in the disposal of waste electrical and electronic equipment (WEEE). The application of an air separation technology to produce comminuted PCB particles can achieve efficient separation of metal and nonmetallic fractions for further treatment and purification. With the advantages of a simple operation, environmental-soundness, and avoidance of secondary pollution, this technology is of great significance in the recycling of waste PCBs. In this paper, the air separation principles of waste PCB particles in a fluidized bed were mathematically analyzed. The shape factor of metal and non-metallic particles and the uneven airflow velocity distribution in the radial dimension were considered, and the formula for metal grade and yield were deduced. Experiments were designed and performed to obtain metal grade and yield data, which were compared with the calculation results. The calculated grade is in good agreement with the experimental results. The presented mathematical analysis can act as a guide for the engineering design and operating configuration of air separation for waste PCB particles in determining the terminal velocity and for selecting the particle size, feed volume, and discharging height.

Оценка изнашиваемости рабочих валков чистовой группы НШПС-1700 АО «АрселорМиттал Темиртау»

The decrease of the rolls wear is an important reserve of the improvement of rolling production. At present during rolling metal of all kinds at the wide-strip rolling mill CWRM-1700 by the JSC “ArselorMittal Temirtau” work rolls of the Hi-Cr type are used in stands No. 6–8, whereas work rolls of the ICDP type are used in stands No. 9–12 for finish rolling. Initial and worn profiles of rolls were determined using the instrument ID 05009. Measurements were performed after roll reloading and cooling, mainly before polishing, with the accuracy of ± 0.01 mm. The amount, assortment and steel grades of the rolled metal, as well as diameters, chemical composition and hardness of the rolls were also fixed. In general research permitted to estimate the wear of the work rolls of the finishing group of CWRM-1700 using geometrical, kinematic and energy indicators of wear. The energy indicator is universal since it takes into account the decrease of the body size from unit work of friction forces on unit roll surface. The kinematic indicator takes into account the decrease of the roll radius relative to unit friction path of the roll surface. The change of geometrical wear indicators of rolls with the same properties in different stands makes it necessary to take account of technological factors that were taken into account while calculating kinematic and energy indicators.

Extended evaluation of Erichsen cupping test results by means of laser speckle

Erichsen cupping test has usually been used to determine the height of the cup at the moment of sheet metal fracture, defined as the Erichsen Number IE. The paper presents a proposal of using Erichsen cupping test to determine the additional parameter – the height of the cup LN-IE at the moment of localized necking in sheet metal, which usually precedes fracture of sheet metal. For this purpose, a method of localized necking detection was developed. It is based on the phenomenon of laser speckle. The results of height measurements were presented for three different grades of sheet metals used in the automotive industry: 5754 H22 aluminum alloy, DC04 deep drawing steel, and Dogal 800DP high strength steel. The differences in cup heights at the moments of localized necking (LN-IE) and fracture (IE) of the tested sheet metals were in the range of 0–8%.

Bulk sample testing for metallurgical characterisation of surficial uranium mineralisation at the Central Jordan Uranium Project

Metallurgical characterisation of uranium mineralisation at the Central Jordan Uranium Project (CJUP) used 13 bulk samples chosen using a novel approach to confirm their representativeness. The bulk samples are considered to be representative of the entirety of the studied deposit if they provide good spatial coverage of the deposit, and their composition matches every fifth percentile or, at least, fifth, twenty-fifth, fiftieth, seventy-fifth and ninety-fifth percentiles, of the selective mining unit (SMU) compositions. The compositional representativeness of bulk samples is checked by plotting against histograms of SMU blocks, including comparisons of metal grades and metallurgically deleterious elements. This approach used bulk samples collected from the Khan Azabib and Siwaqa domains of the CJUP deposit. The test work results indicate that surficial uranium mineralisation within the CJUP deposit is amenable for leaching under alkaline conditions. Uranium can be recovered by heap leach technology, yielding a recovery of 80–90% during testing. One alternative approach is beneficiating the ore by wet scrubbing, another technology that may be a viable approach to exploiting the CJUP deposit and an area that certainly warrants further metallurgical studies.

Effects of decontamination solutions on the surface of titanium: investigation of surface morphology, composition, and roughness.

To investigate the impact of treatments used to detoxify dental implants on the oxide layer morphology and to infer how changes in morphology created by these treatments may impact re-osseointegration of an implant. Pure titanium (cpTi) and the alloy Ti6Al4V were subjected to a series of chemical treatments and mechanical abrasion simulating surface decontamination of dental implants. The morphology and roughness of the surface layer before and after treatment with these solutions were investigated with optical and atomic force microscopy (OM, AFM). The solutions employed are typically used for detoxification of dental implants. These included citric acid, 15% hydrogen peroxide, chlorhexidine gluconate, tetracycline, doxycycline, sodium fluoride, peroxyacetic acid, and treatment with carbon dioxide laser. The treatments consisted of both immersions of samples in solution and rubbing with cotton swabs soaked in solution for 1, 2, and 5 min. Cotton swabs used were analyzed with energy dispersive spectroscopy (EDS). The microscopy investigation showed that corrosion and pitting of the samples were present in both metal grades with immersion and rubbing methods when employing more acidic solutions, which had pH <3. Mildly acidic solutions caused surface discoloration when coupled with rubbing but did not cause corrosion with immersion. Neutral or basic treatments resulted in no signs of corrosion with both methods. EDS results revealed the presence of titanium particles on all rubbing samples. It was demonstrated in this study that acidic environments coupled with rubbing are able to introduce noticeable morphological changes and corrosion on the surface of both titanium grades.

Evolution of a Laser Hybrid Welding Map

Laser arc hybrid welding combines the advantages but also the complex physical mechanisms of gas metal arc welding and laser keyhole welding. From manifold mainly experimental but also theoretical research results a map with versatile functions was initiated for the first time. The purpose is to survey the overall context and to facilitate navigation to the various phenomena that are shown through case studies accompanied by theoretical explanations and guidelines for optimization. Though not complete, the map enables systematic and graphical navigation to relevant publications. Based on a fundamental structure of the map, which was decided early, it is inherently extendable in the future by adding existing and new knowledge, also from other research groups, enabling evolution. The fundament of the map structure comprises gouge thickness, joint type and metal grade, in coherence with product and weld designers’ starting points. The next hierarchy level of the map offers options in the joint type as well as in hybrid welding techniques. The latter contains techniques like double-sided welding, pulse shaping management of the arc or laser, CMT arcs, tandem arcs, or remelting of undercuts. In addition to laser-arc hybrid welding, other hybrid laser techniques like multilayer hot-wire laser welding of narrow gaps or hybrid laser friction stir welding can be taken into account. At the other end of the hierarchy, the map offers via a database-like archive electronic navigation to research results like weld macrographs, high speed imaging or numerical simulation results of the welding process.

Improving processing by adaption to conditional geostatistical simulation of block compositions

One of the key usages of geostatistics has long been the prediction of the spatial structure of orebodies. This is used for the evaluation of resources and/or reserves and for further planning of the mining and beneficiation process schedule. For most applications, and until quite recently, metal grade has been regarded as the central property of study and the main objective has been to distinguish between ore and waste. However, recently other properties have come into focus through better analytical methods, such as automated mineralogy (see e.g. Fandrich et al. 2007), and new geostatistical methods considering more complex information, such as kriging of compositions (Pawlowsky-Glahn and Olea, 2004). Two ores with the same chemical composition can have totally different mineralogies and microfabrics, which will result in different recoveries, energy requirements, or reagent consumptions, thus yielding very different mass streams. An ore is thus no longer understood as represented by a single value element, but through a complex microfabric (Hagni, 2008). This perspective allows quantitative insight into relevant properties of different ore and gangue minerals (Sutherland and Gottlieb, 1991), potentially containing poison elements or phases (e.g. Houot, 1983) that modify the efficiency of downstream processing steps or require additional treatment. Accordingly, processing choices have become more complex. Grade-based studies allow a mere ‘beneficiate-or-dump’ decision. With the advent of these analytical and methodological advances, it is possible to better adapt processing to the ore mined due to a more profound understanding of the processing required. For instance, good knowledge of microfabric properties can reduce energy consumption, if overgrinding is avoided, which also results in improved recovery by avoiding losses due to poor liberation (Wills and Napier-Munn, 2006). Similarly, accurate information on mineral composition may permit the specification of a cut-off in any separation technique (magnetic, electrostatic, or density-based), optimally weighting recovery and further processing costs. Or depending on the proportion of fines generated during milling, desliming might or might not be necessary. Finally, different concentrations of chemicals might be needed for an optimal flotation process as a function of the composition of the concentrate. These Improving processing by adaption to conditional geostatistical simulation of block compositions

The multielement metal-bearing capacity of the Korf and Echvayam brown coal deposits (Kamchatka)

The results from studying the rare, trace, non-ferrous, and precious metals in coals and carbonaceous rocks of Korf and Echvayam brown coal deposits (Kamchatka Krai) are given. It was established that brown coals contain economic cut-off grades of Sc, V, Cu, REEs, and platinum group metals that are typical of the known types of ores. The data on the contents of a number of metals in coals of the Korf and Echvayam deposits (Kamchatka Krai) are published for the first time.

Drilling Shallow-Water Massive Sulfides at the Palinuro Volcanic Complex, Aeolian Island Arc, Italy

A subseafloor replacement-style barite and sulfide occurrence was drilled in shallow waters at the Palinuro volcanic complex, the northernmost Aeolian arc volcano in the Tyrrhenian Sea, Italy. Using a lander-type drilling device, 11 successful drill holes yielded a total of 13.5 m of core from a sediment-filled depression located at a water depth of 630 to 650 m. The longest continuous drill core recovered consists of 4.84 m of massive to semimassive barite and sulfides with abundant late, native sulfur overprint. Seafloor observations suggest that the hydrothermal system associated with the formation of the subseafloor barite and sulfide ore zone is still active, although black smoker activity does not occur on the seafloor. The recovered drill core shows that the subseafloor deposit is zoned with depth. The top of the mineralized zone is comprised of a variably silicified vuggy barite-sulfide facies that shows notable polymetallic metal enrichment, while the deeper portion of the mineralized zone is dominated by massive pyrite having distinctly lower base and precious metal grades. Metal zonation of the barite and sulfide deposit is related to the evolution of the hydrothermal fluids in space and time. The barite cap and the massive pyrite present in the deeper portion of the mineralized zone appear to have formed early in the paragenesis. During the main stage of the mineralization, the barite cap was brecciated and cemented by a polymetallic assemblage of barite and pyrite with minor chalcopyrite and tetrahedrite, trace famatinite, and rare cinnabar. Lower temperature precipitates formed during the main stage of mineralization include sphalerite, galena, pyrite, opal-A, and barite, which are associated with traces of Pb-Sb-As sulfosalts such as bournonite-seligmannite, or semseyite. A distinct mineral assemblage of fine-grained anhedral enargite, hypogene covellite, chalcopyrite, and galena is commonly associated with colloform sphalerite, galena, and pyrite as a late phase of this main stage. Colloform pyrite and marcasite are the last sulfides formed in the paragenetic sequence. The deposit is interpreted to have formed from fluids having an intermediate-sulfidation state, although excursions to high- and very high sulfidation states are indicated by the presence of abundant enargite and hypogene covellite. Laser ablation and conventional sulfur isotope analyses show that pyrite formed close to the seafloor within the zone of polymetallic metal enrichment has a variable sulfur isotope composition (δ34S = −39 to +3‰), whereas a more narrow range is observed in the massive pyrite at depth (δ34S = −10 to 0‰). Similar variations were also documented for the late native sulfur overprint. Overall, the negative sulfur isotope ratios at depth, the intermediate- to very high sulfidation conditions during mineralization, and the abundance of native sulfur suggest contributions of magmatic volatiles to the mineralizing fluids from a degassing magma chamber at depth. Biological processes are interpreted to have played a major role during late stages of ore formation. The combination of a subseafloor replacement deposit with a massive to semimassive barite cap rock overlying massive pyrite, the intermediate- to high-sulfidation characteristics, and the strong biological influence on the late stages of mineralization are distinct from other modern seafloor massive sulfide deposits and represents a style of submarine mineralization not previously recognized in a modern volcanic arc environment. The barite and sulfide occurrence at Palinuro shares many characteristics with porphyry-related base metal veins and intermediate-sulfidation epithermal deposits, suggesting that metallogenic processes associated with arc-related magmatic-hydrothermal systems are not restricted to the subaerial environment.

Update of energy payback time and greenhouse gas emission data for crystalline silicon photovoltaic modules

AbstractResults of a recent photovoltaic energy life cycle study are presented. The focus lies on the energy payback time (EPBT) and the CO2 emission rate achievable with state‐of‐the‐art industrial production chains for conventional monocrystalline and multicrystalline silicon modules. The data have been provided by European manufacturers and represent the processes in their European—primarily German—production sites. The analysis covers all steps from metal grade silicon refinement down to assembled modules as shipped to the customer. Balance of system contributions have not been included in the analysis and in the result figures, both for EPBT and CO2 emissions. The resulting EPBT values for the modules only are 1.09 and 0.93 years for monocrystalline and multicrystalline silicon, respectively, both under southern European conditions. CO2 emission rates strongly depend on the scenario considered, ranging from 18 g/kWh in southern Europe to 60 g/kWh in northern Germany under worst‐case conditions for useful lifetime and degradation. Copyright © 2014 John Wiley &amp; Sons, Ltd.