Sulfur Partition Research Articles

Industrial Application of Desulfurization Using Low Basicity Refining Slag in Tire Cord Steel

Desulfurization performance with low binary basicity refining slag in 72 grade tire cord steel was calculated using FactSage and it is found that sulfur content in steel decreases with the increase of basicity of slag, MgO content in slag and slag/steel ratio while sulfur partition ratio between slag and steel increases gradually with the increase of basicity of slag as well as MgO content. Experiments were carried out and the results are of great agreements with theoretical calculation. Then industrial application tests were performed in a domestic plant and good results were achieved. Sulfur content in steel decreases gradually during refining process, as a result, sulfur content in the billets is controlled in the range of 0.0071%–0.0081%. Sulfur content in steel refined with slag basicity of 1.21 is lower than that of 1.02, while the plasticity of oxide compound inclusions is a little better controlled in low basicity heats. Using refining slag with basicityof 1.0-1.2 and MgO content of 5%–10% and reducing the slag takeover of LD are favorable for improving the desulfurization performance and the plasticity of inclusions during the industrial production.

The partitioning of sulfur and chlorine between andesite melts and magmatic volatiles and the exchange coefficients of major cations

Andesite melts were equilibrated with an H–O–S-bearing volatile phase to determine the partition coefficients for S and Cl as a function of melt composition and oxygen fugacity. The experiments were conducted in rapid-quench MHC vessel assemblies at 200MPa and 1000°C, and over a range of imposed fO2 between NNO−1.2 and NNO+1.8. High fluid/melt mass ratios (∼15) were employed, allowing precise and accurate partition coefficients to be obtained by mass balance calculations. Chlorine exhibits Henrian behavior at ClO−0.5 activities typical for arc magmas, with DClvolatile/melt=1.36±0.06 (1σ) below 0.2wt.% Cl in the melt; at higher ClO−0.5 activities, DClvolatile/melt increases linearly to 2.11±0.02 at 1wt.% Cl in the melt. In the volatile phase: FeCl2∼NaCl>KCl∼HCl. The determination of cation exchange coefficients for major cations yielded: KK,Navolatile/melt=1.23±0.10 (1σ) and ∗KFe,Navolatile/melt=DFevolatile/melt/DNavolatile/melt=1.08±0.16 (1σ). Under these conditions, the concentration of HCl in the vapor is negatively correlated with the (Na+K)/(Al+Fe3+) ratio in the melt. Reduced sulfur (S2−) appears to obey Henry’s law in andesite melt–volatile system at fH2S below pyrrhotite saturation. The partition coefficient for S at fO2=NNO−0.5 correlates negatively with the FeO concentration in the melt, changing from 254±25 at 4.0wt.% FeO to 88±6 at 7.5wt.% FeO. Pyrrhotite saturation is reached when approximately 3.2mol% S is present in the volatile phase at fO2=NNO−0.5. At the sulfide/sulfate transition, the partition coefficient of S drops from 171±23 to 21±1 at a constant FeO content of ∼6wt.% in the melt. At fO2=NNO+1.8, anhydrite saturation is reached at ∼3.3mol% S present in the volatile phase. Aqueous volatiles exsolving from intermediate to mafic magmas can efficiently extract S, and effect its transfer to sites of magmatic-hydrothermal ore deposit formation.

Control of sulfur partitioning between primary and secondary metabolism in Arabidopsis

Sulfur is an essential nutrient for all organisms. Plants are able to take up inorganic sulfate and assimilate it into a range of bio-organic molecules either after reduction to sulfide or activation to 3′-phosphoadenosine 5′-phosphosulfate. While the regulation of the reductive part of sulfate assimilation and the synthesis of cysteine has been studied extensively in the past three decades, much less attention has been paid to the control of synthesis of sulfated compounds. Only recently the genes and enzymes activating sulfate and transferring it onto suitable acceptors have been investigated in detail with emphasis on understanding the diversity of the sulfotransferase gene family and the control of partitioning of sulfur between the two branches of sulfate assimilation. Here, the recent progress in our understanding of these processes will be summarized.

Fuel characteristics of wheat-based Dried Distillers Grains and Solubles (DDGS) for thermal conversion in power plants

For many years, the sole use of Dried Distillers Grains and Solubles (DDGS) has been as a feed for livestock, due to its high protein and fiber content. Recently there has been interest in DDGS as a power station fuel. In this study, DDGS produced from wheat has been studied for its fuel properties. Pyrolysis studies were conducted via Thermogravimetric Analysis (TGA) and pyrolysis gas chromatography–mass spectrometry (py GC–MS): the former was used to calculate the apparent first order kinetics while the latter helped to characterise pyrolysis products such as methoxyphenols and long chain fatty acids and esters. Fast heating rate chars were made, and nitrogen and sulphur partitioning between volatiles and chars are reported. In addition the chars were studied for their combustion behavior via Simultaneous Thermogravimetric Analysis with Mass Spectrometry detection (STA–MS) to study the conversion of char nitrogen and sulphur to different nitrogen and sulphur-containing species. In addition DDGS was combusted in a 50 kW fluid bed furnace, and the nitrogen species also monitored. DDGS is predicted to have a high alkali index that predicts high fouling tendency due to the high potassium and sodium contents in the ash. The phosphorus content in DDGS ash is also very high. Pyrolysis studies showed some oil evaporation/decomposition occurring at lower temperatures compared to decomposition of the lignocellulosic material. Nitrogen and sulphur partitioning showed that approximately 91% N and 94% S were given off as volatiles. The char was enriched with nitrogen but depleted in sulphur. Char combustion took place in two distinct stages indicating the presence of two types of chars, which yield selective evolution of S and N species during their combustion. Fluid bed combustion studies showed release of both HCN and ammonia during initial stages, when the bed is heating and the fuel undergoes devolatilisation. Steady-state combustion gave NO and N 2O emissions of 290 and 30 ppm respectively, with HCN and NH 3 emissions dropping to below 1 ppm. Agglomeration of the bed was avoided by keeping the combustion temperature below 900 °C

Soil sulfur fractions dynamics and distribution in a tropical grass pasture amended with nitrogen and sulfur fertilizers

AbstractSoil sulfur (S) partitioning among the various pools and changes in tropical pasture ecosystems remain poorly understood. Our study aimed to investigate the dynamics and distribution of soil S fractions in an 8‐year‐old signal grass (Brachiaria decumbens Stapf.) pasture fertilized with nitrogen (N) and S. A factorial combination of two N rates (0 and 600 kg N ha–1 y–1, as NH4NO3) and two S rates (0 and 60 kg S ha–1 y–1, as gypsum) were applied to signal grass pastures during 2 y. Cattle grazing was controlled during the experimental period. Organic S was the major S pool found in the tropical pasture soil, and represented 97% to 99% of total S content. Among the organic S fractions, residual S was the most abundant (42% to 67% of total S), followed by ester‐bonded S (19% to 42%), and C‐bonded S (11% to 19%). Plant‐available inorganic SO4‐S concentrations were very low, even for the treatments receiving S fertilizers. Low inorganic SO4‐S stocks suggest that S losses may play a major role in S dynamics of sandy tropical soils. Nitrogen and S additions affected forage yield, S plant uptake, and organic S fractions in the soil. Among the various soil fractions, residual S showed the greatest changes in response to N and S fertilization. Soil organic S increased in plots fertilized with S following the residual S fraction increment (16.6% to 34.8%). Soils cultivated without N and S fertilization showed a decrease in all soil organic S fractions.

Two stage fluid bed-plasma gasification process for solid waste valorisation: Technical review and preliminary thermodynamic modelling of sulphur emissions

Gasification of solid waste for energy has significant potential given an abundant feed supply and strong policy drivers. Nonetheless, significant ambiguities in the knowledge base are apparent. Consequently this study investigates sulphur mechanisms within a novel two stage fluid bed-plasma gasification process. This paper includes a detailed review of gasification and plasma fundamentals in relation to the specific process, along with insight on MSW based feedstock properties and sulphur pollutant therein. As a first step to understanding sulphur partitioning and speciation within the process, thermodynamic modelling of the fluid bed stage has been performed. Preliminary findings, supported by plant experience, indicate the prominence of solid phase sulphur species (as opposed to H2S) – Na and K based species in particular. Work is underway to further investigate and validate this.

Effect of Additives on Desulfurization Capability of CAS-OB Refining Ladle Slag

To avoid slag sticking onto the ladle snorkel during the CAS-OB refining and alloying process, CaO-B2O3 and CaO-CaF2 were respectively employed as modifiers added into the ladle slag. The desulfurization capability of modified slag was investigated. The results of experiments on sulphur partition equilibrium between metal and slag indicate that the sulphur content of metal can be further decreased by the modified slag. When CaO-B2O3 is used as additive and the mass ratio of CaO to B2O3 is 1:1, the desulfurization ratio of slag to liquid steel is 50%, the final sulphur content can be controlled at 0.002%. The efficiency of desulfurization is fine. When CaO- CaF2 is employed as additive and the mass ratio of CaF2 to CaO is 2:8, the final sulphur content of metal can be controlled lower than 0.004%, the efficiency of desulfurization is also acceptable.

A New Approach for the Diffusion Coefficient Evaluation of Sulfur in CaO-SiO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub> Slag

The Diffusion coefficient of sulfur in a ternary slag with composition of 51.5% CaO- 9.6% SiO2- 38.9% Al2O3 was measured at 1723 K by chemical diffusion from the variation of concentration of sulfur in silver metal. A MATLAB program was developed to find the concentration variation of sulfur in silver metal using various critical parameters like the diffusion coefficient of sulfur in slag available in literature, sulfur partition ratio, sulfide capacity of the slag and the its density. The PS2 and PO2 pressures were calculated from the Gibbs energy of the equilibrium reaction between CaO in the slag and solid CaS and confirming the same by using ThermoCalc. The density of the slag at 1723 K was obtained from earlier experiments. Initially the order of magnitude for the diffusion coefficient was taken from the works of Saito and Kawai but later was modified so that the concentration changes of Sulfur obtained from the program agreed with the experimental results. The diffusion coefficient of sulfur in 51.5% CaO- 9.6% SiO2- 38.9% Al2O3 slag at 1723 K was estimated as 4.14x10-6 cm2/sec.

C–O–H–S fluids and granitic magma: how S partitions and modifies CO2 concentrations of fluid-saturated felsic melt at 200 MPa

Hydrothermal volatile-solubility and partitioning experiments were conducted with fluid-saturated haplogranitic melt, H2O, CO2, and S in an internally heated pressure vessel at 900°C and 200 MPa; three additional experiments were conducted with iron-bearing melt. The run-product glasses were analyzed by electron microprobe, FTIR, and SIMS; and they contain ≤0.12 wt% S, ≤0.097 wt% CO2, and ≤6.4 wt% H2O. Apparent values of log fO2 for the experiments at run conditions were computed from the [(S6+)/(S6++S2−)] ratio of the glasses, and they range from NNO −0.4 to NNO + 1.4. The C–O–H–S fluid compositions at run conditions were computed by mass balance, and they contained 22–99 mol% H2O, 0–78 mol% CO2, 0–12 mol% S, and <3 wt% alkalis. Eight S-free experiments were conducted to determine the H2O and CO2 concentrations of melt and fluid compositions and to compare them with prior experimental results for C–O–H fluid-saturated rhyolite melt, and the agreement is excellent. Sulfur partitions very strongly in favor of fluid in all experiments, and the presence of S modifies the fluid compositions, and hence, the CO2 solubilities in coexisting felsic melt. The square of the mole fraction of H2O in melt increases in a linear fashion, from 0.05 to 0.25, with the H2O concentration of the fluid. The mole fraction of CO2 in melt increases linearly, from 0.0003 to 0.0045, with the CO2 concentration of C–O–H–S fluids. Interestingly, the CO2 concentration in melts, involving relatively reduced runs (log fO2 ≤ NNO + 0.3) that contain 2.5–7 mol% S in the fluid, decreases significantly with increasing S in the system. This response to the changing fluid composition causes the H2O and CO2 solubility curve for C–O–H–S fluid-saturated haplogranitic melts at 200 MPa to shift to values near that modeled for C–O–H fluid-saturated, S-free rhyolite melt at 150 MPa. The concentration of S in haplogranitic melt increases in a linear fashion with increasing S in C–O–H–S fluids, but these data show significant dispersion that likely reflects the strong influence of fO2 on S speciation in melt and fluid. Importantly, the partitioning of S between fluid and melt does not vary with the (H2O/H2O + CO2) ratio of the fluid. The fluid-melt partition coefficients for H2O, CO2, and S and the atomic (C/S) ratios of the run-product fluids are virtually identical to thermodynamic constraints on volatile partitioning and the H, S, and C contents of pre-eruptive magmatic fluids and volcanic gases for subduction-related magmatic systems thus confirming our experiments are relevant to natural eruptive systems.

A Proposal for a Novel Method to Measure the Diffusivity of Species in Slag

The rate of reactions involved in steel-refining operations largely depend on the transport of species through the slag or metal phase at steel refining temperatures; the intrinsic reaction rates are expected to be high. Therefore, the study of diffusivity of species in slag is of great importance. The present work proposes a new methodology, in which experiments can be designed to determine the diffusivity of species in liquid slag. In this article, a mathematical description for the methodology is formulated and subsequently solved using numerical methods. This exercise will help in identifying appropriate bounds for experimental parameters for a desired accuracy. The proposed methodology is generic for any species in the liquid slag phase. However, diffusion of sulfur through slag has been illustrated as a case study. The order of magnitude for the diffusion coefficient for sulfur was taken from the classic works of Saito and Kawai, the sulfide capacity and sulfur partition ratio were retrieved from the works of Taniguchi et al., and the slag density was retrieved from earlier experimental results of the present authors. The slag density was obtained from earlier experimental results from the present group. The Henrian activity coefficients were retrieved from literature. Subsequent to the present work, the design of experiments and measurements carried out using the proposed methodology and the results obtained are presented as the second article on this subject.

Effect of B&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; on Melting Temperature, Viscosity and Desulfurization Capacity of CaO&amp;ndash;based Refining Flux

Fluorite is widely employed as fluxing agent in metallurgy flux, which inevitably leads to serious fluorine pollution. In this work, B2O3 is used as fluxing agent of CaO–based refining flux to substitute for CaF2 so as to decrease the melting temperature and to improve the speed of slag forming and the refining efficiency. The effects of B2O3 on the melting temperature, viscosity and desulfurization capacity of CaO–based refining flux were investigated. The results indicate that the fluxing action of B2O3 is better than that of CaF2 and Al2O3. For the high basicity CaO–based refining flux (mass ratio of CaO/SiO2 is 5.0–8.75), when CaF2 is substituted with B2O3, the melting temperature can be decreased remarkably. Especially, when the mass ratios of CaO/Al2O3 and CaO/SiO2 are in range of 1.1–4.0 and 5.25–8.0, respectively, the flux melting temperature is lower than 1300°C. At the same time, the temperature range, in which the flux viscosity is low, is expanded as well as the stability of flux viscosity varying with temperature is improved obviously. These variations of flux properties are favorable for refining process. The results of experiments on sulphur partition equilibrium between metal and flux indicate that the desulfurization capacity of flux can be improved markedly when CaF2 is substituted with equal mass of B2O3. When 4 mass% B2O3 is employed as fluxing agent and the mass ratio of CaO/Al2O3 is in the range of 1.5–7.0, the final sulfur content of metal can be controlled lower than 0.004%.

Control of sulfur partitioning between primary and secondary metabolism

Sulfur is an essential nutrient for all organisms. Plants take up most sulfur as inorganic sulfate, reduce it and incorporate it into cysteine during primary sulfate assimilation. However, some of the sulfate is partitioned into the secondary metabolism to synthesize a variety of sulfated compounds. The two pathways of sulfate utilization branch after activation of sulfate to adenosine 5'-phosphosulfate (APS). Recently we showed that the enzyme APS kinase limits the availability of activated sulfate for the synthesis of sulfated secondary compounds in Arabidopsis. To further dissect the control of sulfur partitioning between the primary and secondary metabolism, we analysed plants in which activities of enzymes that use APS as a substrate were increased or reduced. Reduction in APS kinase activity led to reduced levels of glucosinolates as a major class of sulfated secondary metabolites and an increased concentration of thiols, products of primary reduction. However, over-expression of this gene does not affect the levels of glucosinolates. Over-expression of APS reductase had no effect on glucosinolate levels but did increase thiol levels, but neither glucosinolate nor thiol levels were affected in mutants lacking the APR2 isoform of this enzyme. Measuring the flux through sulfate assimilation using [(35) S]sulfate confirmed the larger flow of sulfur to primary assimilation when APS kinase activity was reduced. Thus, at least in Arabidopsis, the interplay between APS reductase and APS kinase is important for sulfur partitioning between the primary and secondary metabolism.

The distribution of sulfur between haplogranitic melts and aqueous fluids

Abstract The distribution of sulfur between haplogranitic melt and aqueous fluid has been measured as a function of oxygen fugacity (Co–CoO-buffer to hematite–magnetite buffer), pressure (0.5–3 kbar), and temperature (750–850 °C). Sulfur always strongly partitions into the fluid. At a given oxygen fugacity, pressure and temperature, the distribution of sulfur between melt and fluid can be described by one constant partition coefficient over a wide range of sulfur concentrations. Oxygen fugacity is the most important parameter controlling sulfur partitioning. While the fluid/melt partition coefficient of sulfur is 468 ± 32 under Co–CoO buffer conditions at 2 kbar and 850 °C, it decreases to 47 ± 4 at an oxygen fugacity 0.5–1 log unit above Ni–NiO at the same pressure and temperature. A further increase in oxygen fugacity to the hematite–magnetite buffer has virtually no effect on the partition coefficient (Dfluid/melt = 49 ± 2). The dependence of Dfluid/melt on temperature and pressure was systematically explored at an oxygen fugacity 0.5–1 log units above Ni–NiO. At 850 °C, the effect of pressure on the partition coefficient is small (Dfluid/melt = 58 ± 3 at 0.5 kbar; 94 ± 9 at 1 kbar; 47 ± 4 at 2 kbar and 68 ± 5 at 3 kbar) and temperature also has only a minor effect on partitioning. The data show the “sulfur excess” observed in many explosive volcanic eruptions can easily be explained by the presence of a small fraction of hydrous fluid in the magma chamber before the eruption. The sulfur excess can be calculated as the product of the fluid/melt partition coefficient of sulfur and the mass ratio of fluid over melt in the erupted material. For a plausible fluid/melt partition coefficient of 47 under oxidizing conditions, a 10-fold sulfur excess corresponds to a 17.6 wt.% of fluid in the erupted material. Large sulfur excesses (10-fold or higher) are only to be expected if only a small fraction of the magma residing in the magma chamber is erupted. The behavior of sulfur, which seems to be largely independent of pressure and temperature under oxidizing conditions is very different from chlorine, where the fluid/melt partition coefficient strongly increases with pressure. Variations in the SO2/HCl ratio of volcanic gases, if they reflect primary processes in the magma chamber, therefore provide an indicator of pressure variations in a magma. In particular, major increases in the S/Cl ratio of an aqueous fluid coexisting with a felsic magma suggest a pressure reduction in the magma chamber and/or magma rising to the surface.

Partitioning of hazardous trace elements during coal preparation

The samples of feed coal, cleaned coal, middlings, slime and gangue were collected from Xiqu, Antaibao and Heidaigou coal preparation plants, China. The analyses of minerals, ash, sulfur and 20 hazardous trace elements were performed on the samples by SEM/EDX, INAA, ICP-AES, CV-AAS, GAAS and also on the samples from experimental products (by heavy-media, electrostatic separation and forth-floatation). Partitioning of sulfur and these trace elements under the conditions of different coal ranks and coal preparation types were discussed. The results show that the partitioning behavior of a given element during the cleaning processes is mainly controlled by its modes of occurrence, the distribution forms of its carrier minerals and the cleaning technique types. Although hazardous trace elements have diverse degrees of removal due to different coal ranks and coal preparation types, the elements associated with fine minerals (e.g. Pb, U and Be) and organic constituents (e.g. Br and Cl ) will not be effectively reduced by physical coal cleaning and may still be enriched in the cleaned coal. As to the coarse sized feeds (particle size >0.5 mm), the elements associated with coarse/epigenetic minerals can be removed more easily by gravity separation methods and report to the gangue and slime. As to the finer-grained feeds (<0.5 mm), the elements associated with minerals with a high dielectric coefficient are easily removed by electrostatic separation; in comparison with the larger-sized fractions (74–150 µm), the smaller-sized fractions (<74 µm) show a high removability of elements by forth-floatation as a whole. The physical coal cleaning is not only effective in the removal of ash and sulfur, but also in reducing the concentration of most hazardous trace elements. However, as byproducts, the middlings, especially the slimes are preferentially enriched in many hazardous elements (e.g. Cr, Ni and Mo), so that these fractions have a potential of environmental risk and should not be directly used as fuel.

The Plinian Lower Pumice 2 eruption, Santorini, Greece: Magma evolution and volatile behaviour

The Plinian Lower Pumice 2 (LP2) eruption (172 ka) was one of the first major caldera-forming eruptions of the Santorini volcanic complex (Greece). The eruption shows some striking similarities to the caldera-forming Late Bronze Age (Minoan) eruption in terms of field, petrological and geochemical characteristics of its eruptive products, which are used to reveal the storage conditions of the LP2 magmas, pre-eruptive magmatic processes and the behaviour and degassing of volatiles prior to and during eruption. The LP2 eruption comprises four, predominantly rhyodacitic eruptive units (LP2-A, B, C, D). The lowermost unit of the Plinian LP2 deposits (LP2-A) consists of a basal phreatomagmatic bed (LP2-A1), which is overlain by three discrete pumice fall deposits (LP2-A2-1, A2-2, A3), the most prominent of which (LP2-A3) contains abundant, quench-textured scoriae that range in composition from basalt to basaltic andesite. The eruption proceeded with the deposition of pumice-rich pyroclastic flows (LP2-B) characterised by a lower, stratified and cross-bedded ignimbrite (LP2-B1) that may grade into a massive, non-welded ignimbrite (LP2-B2), a lithic-rich pumiceous breccia (LP2-C) and a co-ignimbrite lithic lag breccia (LP2-D). The main volume of rhyodacitic magma, which formed by fractionation of olivine, clinopyroxene, orthopyroxene, plagioclase, amphibole, Fe–Ti oxides, pyrrhotite and apatite from basaltic parental magmas and assimilation of crustal rocks, was held at mid-crustal levels (≤ 16 km depth), magmatic temperatures of 831 ± 12 °C and an oxygen fugacity slightly above the fayalite–magnetite–quartz (FMQ) oxygen buffer. Injection of ∼ 200 °C hotter mafic magma into the rhyodacitic reservoir and subsequent mingling and minor hybridisation with the resident magma helped to remobilise the rhyodacitic host magma and determined the final compositional range of the erupted products. Melt inclusion data show that sulphur concentrations were reduced to < 270 ppm in the rhyodacite, primarily due to partitioning of sulphur into pyrrhotite or, depending on temperature, a FeS-rich melt during magmatic differentiation at oxygen fugacities around the FMQ oxygen buffer. Sulphur concentrations in groundmass glasses of the LP2 pumices suggest that ∼ 43% of the remaining sulphur was released into the atmosphere during the LP2 eruption, the climatic effects of which are considered minor when compared to eruptions of more oxidised silicic arc magmas. Chlorine remained dissolved in the melt during magmatic differentiation prior to and during the LP2 eruption, indicating that chlorine emissions to the atmosphere were negligible.

Effect of pressure, temperature, and oxygen fugacity on the metal-silicate partitioning of Te, Se, and S: Implications for earth differentiation

We have measured liquid Fe metal–liquid silicate partitioning ( D i) of tellurium, selenium, and sulfur over a range of pressure, temperature, and oxygen fugacity (1–19 GPa, 2023–2693 K, fO 2 −0.4 to −5.5 log units relative to the iron-wüstite buffer) to better assess the role of metallic melts in fractionating these elements during mantle melting and early Earth evolution. We find that metal-silicate partitioning of all three elements decreases with falling FeO activity in the silicate melt, and that the addition of 5–10 wt% S in the metal phase results in a 3-fold enhancement of both D Te and D Se. In general, Te, Se, and S all become more siderophile with increasing pressure, and less siderophile with increasing temperature, in agreement with previous work. In all sulfur-bearing experiments, D Te is greater than D Se or D S, with the latter two being similar over a range of P and T. Parameterized results are used to estimate metal-silicate partitioning at the base of a magma ocean which deepens as accretion progresses, with the equilibration temperature fixed at the peridotite liquidus. We show that during accretion, Te behaves like a highly siderophile element, with expected core/mantle partitioning of >10 5, in contrast to the observed core/mantle ratio of ∼100. Less extreme differences are observed for Se and S, which yielded core/mantle partitioning 100- to 10 times higher, respectively, than the observed value. Addition of ∼0.5 wt% of a meteorite component (H, EH or EL ordinary chondrite) is sufficient to raise mantle abundances to their current level and erase the original interelement fractionation of metal-silicate equilibrium.

Deoxidization Equilibria with Zirconium and Sulfur Partition for Molten Iron/CaO-Al2O3-ZrO2Slag at 1873K

The relationship of zirconium and oxygen concentrations with sulfide capacity was clarified using equilibrated molten iron with CaO-Al2O3-ZrO2 slag at 1873 K. Al2O3 and CaO-stabilized ZrO2 crucible saturated compositions were equilibrated with CaO-2Al2O3 and crucible solid solution (Css) in the CaO-ZrO2 system, and with CaOZrO2 and Css, respectively. From the concentrations of zirconium and oxygen dissolved in molten iron, ZrO2 activities of the slag of the Al2O3 crucible and ZrO2 crucible compositions were determined to be 0.885 and 0.0343, respectively. On the other hand, the sulfur distribution ratio of the ZrO2 crucible saturated composition was higher than that of the Al2O3 crucible saturated composition. Sulfide capacities were determined to be 6.30×10−5 and 8.07×10−5 in the Al2O3 and the ZrO2 crucible saturated compositions, respectively.

Transformation of Reactive Iron Minerals in a Permeable Reactive Barrier (Biowall) Used to Treat TCE in Groundwater

Iron and sulfur reducing conditions generally develop in permeable reactive barrier systems (PRB) constructed to treat contaminated groundwater. These conditions allow formation of FeS mineral phases. FeS readily degrades TCE, but a transformation of FeS to FeS2 could dramatically slow the rate of TCE degradation in the PRB. This study uses acid volatile sulfide (AVS) and chromium reducible sulfur (CRS) as probes for FeS and FeS2 to investigate iron sulfide formation and transformation in a column study and PRB field study dealing with TCE degradation. Solid phase iron speciation shows that most of the iron is reduced and sulfur partitioning measurements show that AVS and CRS coexist in all samples, with the conversion of AVS to CRS being most significant in locations with potential oxidants available. In the column study, 54% of FeS was transformed to FeS2 after 2.4 years. In the field scale PRB, 43% was transformed after 5.2 years. Microscopy reveals FeS, Fe3S4 and FeS2 formation in the column system; however, only pyrite formation was confirmed byX-ray diffraction. The polysulfide pathway is most likely the primary mechanism of FeS transformation in the system, with S0 as an intermediate species formed through H2S oxidation.

N,N-dialkylimidazolium dialkylphosphate ionic liquids: Their extractive performance for thiophene series compounds from fuel oils versus the length of alkyl group

N-butylimidazole-derived dialkylphosphate ionic liquids (ILs) are demonstrated to be effective for extractive removal of aromatic sulfur compounds (S-compounds) from fuel oils, and show strong preferential extraction for aromatic S-compound versus toluene. Sulfur partition coefficients ( K N ) between IL and fuel oil at 298.15 K are determined experimentally over a wide range of sulfur content. The results show that the sulfur removal selectivity for a specific IL is dependent on the molecular structure of the S-compounds and follows the order dibenzothiophene > benzothiophene > thiophene > 3-methylthiophene, and the efficiency of the ILs for removal of aromatic S-compounds is dependent on the size and structure of both cations and anions of the ILs. For the dialkylphosphate ILs studied with the same anion, the longer the alkyl substitute to the imidazolium ring is the higher the K N value for that IL, and a similar trend is found for the ILs with same cation.

Pre-1991 sulfur transfer between mafic injections and dacite magma in the Mt. Pinatubo reservoir

Before the 1991–1992 activity, a large andesite lava dome belonging to the penultimate Pinatubo eruptive period (Buag ∼ 500 BP) formed the volcano summit. Buag porphyritic andesite contains abundant amphibole-bearing microgranular enclaves of basaltic–andesite composition. Buag enclaves have lower K 2O and incompatible trace element (LREE, U, Th) contents than mafic pulses injected in the Pinatubo reservoir during the 1991–1992 eruptive cycle. This study shows that Buag andesite formed by mingling of a hot, water-poor and reduced mafic magma with cold, hydrous and oxidized dacite. Depending on their size, enclaves experienced variable re-equilibration during mixing/mingling. Re-equilibration resulted in hydration, oxidation and transfer of mobile elements (LILE, Cu) from the dacite to the mafic melts and prompted massive amphibole crystallization. In Buag enclaves, S-bearing phases (sulfides, apatite) and melt inclusions in amphibole and plagioclase record the evolution of sulfur partition among melt, crystal and fluid phases during magma cooling and oxidation. At high temperature, sulfur is partitioned between andesitic melt and sulfides (Ni-pyrrhotite). Magma cooling, oxidation and hydration resulted in exsolution of a S–Cl–H 2O vapor phase at the S-solubility minimum near the sulfide–sulfate redox boundary. Primary magmatic sulfide (pyrrhotite) and xenocrystic sulfide grains (pyrite), recycled together with olivines and pyroxenes from old mafic intrusives, were replaced by Cu-rich phases (chalcopyrite, cubanite) and, partially, by Ba–Sr sulfate. Sulfides degassed and transformed into residual spongy magnetite in response to fS 2 drop during final magma ascent and decompression. Our research suggests that a complete evaluation of the sulfur budget at Pinatubo must take into account the en route S assimilation from the country rocks. Moreover, this study shows that the efficiency of sulfur transfer between mafic recharges and injected magmas is controlled by the extent and rate of mingling, hydrous flushing and melt oxidation. Vigorous mixing/mingling and transformation of the magmatic recharge into a spray of small enclaves is required in order to efficiently strip their primary S-content that otherwise remains locked in the sulfides. Hydrous flushing increases the magma oxidation state of the recharges and modifies their primary volatile concentrations that cannot be recovered by the study of late-formed mineral phases and melt inclusions. Conversely, S stored in both late-formed Cu-rich sulfides and interstitial rhyolitic melt represents the pre-eruptive sulfur budget immediately available for release from mafic enclaves during their decompression.