Sulfur Evolution Research Articles

The mineral and aqueous phase evolution of sulfur and nickel with weathering of pyrrhotite in a low sulfide, granitic waste rock

The release of S and metals from the weathering of waste rock pyrrhotite [Fe(1−x)S] is affected by oxidation pathways, the presence and concentration of Fe-substitution metals (e.g., Ni), and Fe (oxyhydr)oxide products. A 4C (monoclinic) pyrrhotite [Fe7S8, Ni:Fe substitution of about 1:200] in a low sulfide waste rock was weathered in the laboratory and at a field site to identify the evolution of S oxidation, distribution and coordination of Ni, and possible adsorption of Ni on secondary Fe minerals. Mineral phase S was present in the −2, −1, 0, +4, and +6 oxidation states prior to its release as SO42− into solution. The thiosulfate [S2O32−] pathway of sulfide oxidation was indicated by the presence of polythionates and S2O32−. Sulfur as S2O32− was more persistent than sulfite [SO32−] prior to oxidation to SO42−. The release of Ni during the oxidative dissolution of pyrrhotite was influenced by its distribution in the grain: diffuse throughout the grain (solid solution mineral) or concentrated in exsolved pentlandite [(Fe,Ni)9S8] lamellae within the pyrrhotite. With the oxidation of S, Ni coordination changed from bonding with reduced S species to bonding with oxygen prior to its release with SO42−. Sulfur as SO42− typically stayed in solution with release from the pyrrhotite, but the solubility of released Ni was dependent on leachate pH. A near-neutral pH induced the adsorption of Ni onto Fe (oxyhydr)oxides, which formed during oxidation of the pyrrhotite. In some grains, Ni was found concentrated in Fe distal precipitates as opposed to the closer alteration layers/zones of the sulfide grain. Subsequent dissolution of the Fe (oxyhydr)oxides or desorption of Ni with a change in pH provides a delayed release of Ni into solution. This improved understanding of the oxidation pathway of S, coordination and release of Ni, and influence of Fe (oxyhydr)oxides in the weathering of pyrrhotite will assist in determining appropriate reaction-rate factors and element release rates for prediction of acid rock drainage.

Effect of coal particle size on distribution and thermal behavior of pyrite during pyrolysis

Transformation of pyrite in a demineralized subbituminous coal with various coal particle size distributions (PSD) during pyrolysis was investigated using a thermogravimetric analyzer coupled with mass spectrometer (TGA-MS). The residues from pyrolysis were examined by X-ray diffraction (XRD) and scanning electron microscope equipped with an energy-dispersive X-ray spectrometer (SEM-EDS). It is found that the pyrite content is higher in coal with smaller particle size. The reduction of coal particle size is beneficial to the evolution of gaseous sulfur at 350–650°C. The results from XRD and SEM-EDS analyses show that during pyrolysis small coal particles facilitate the formation of low-sulfur Fe–S phases and even elemental iron in char. The isolated pyrite crystals or the aggregates of pyrite are rich in coal with smaller particle size than in larger ones, and this is beneficial to the pyrite conversion and the formation of low-sulfur Fe–S phases in the finer char particles.

Disulfides – Effective radical generators for flame retardancy of polypropylene

The potential of thirteen aliphatic, aromatic, thiuram and heterocyclic substituted organic disulfide derivatives of the general formula R–S–S–R′ as a new group of halogen-free flame retardants (FR) for polypropylene films have been investigated. According to DIN 4102-1 standard ignitibility test, for the first time it has been demonstrated that many of the disulfides alone can effectively provide flame retardancy and self-extinguishing properties to polypropylene (PP) films at already very low concentrations of 0.5 wt%. In an effort to elucidate the mechanism of the thermal decomposition of disulfide derivatives the fragmentation patterns of the evolved gases from a thermogravimetric analyzer (TGA) have been analyzed by simultaneous mass spectrometry (MS) and Fourier transform infrared spectrometry (FTIR). The main decomposition products initiated by homolytic scission of the S–S bond and/or scission of the C–S bond were identified as thiols, aliphatic and aromatic hydrocarbons, isothiocyanates (depending on the disulfide structures) with further evolution of elemental sulfur and sulfur dioxide at temperatures of above 300 °C and 450 °C, respectively. Based on this preliminary study, we have shown that disulfides represented by e.g. diphenyl disulfide (1), 5,5′-dithiobis(2-nitrobenzoic acid) (2), bis(1-phenyl-1H-tetrazol-5yl)-disulfide (4), 2-bisbenzothiazole-2,2′-disulfide (6) and N,N-dithiobis-(phtalimide) (10) constitute a new halogen-free family of additives for flame retarding of polypropylene.

Clues on the Galactic evolution of sulphur from star clusters

(Abridged) The abundances of alpha-elements are a powerful diagnostic of the star formation history and chemical evolution of a galaxy. Sulphur, being moderately volatile, can be reliably measured in the interstellar medium (ISM) of damped Ly-alpha galaxies and extragalactic HII regions. Measurements in stars of different metallicity in our Galaxy can then be readily compared to the abundances in external galaxies. Such a comparison is not possible for Si or Ca that suffer depletion onto dust in the ISM. Furthermore, studying sulphur is interesting because it probes nucleosynthetic conditions that are very different from those of O or Mg. The measurements in star clusters are a reliable tracers of the Galactic evolution of sulphur. We find <A(S)>NLTE=6.11+/-0.04 for M 4, <A(S)>NLTE=7.17+/-0.02 for NGC 2477, and <A(S)>NLTE=7.13+/-0.06 for NGC 5822. For the only star studied in Trumpler 5 we find A(S)NLTE=6.43+/-0.03 and A(S)LTE=6.94+/-0.05. Our measurements show that, by and large, the S abundances in Galactic clusters trace reliably those in field stars. The only possible exception is Trumpler 5, for which the NLTE sulphur abundance implies an [S/Fe] ratio lower by roughly 0.4 dex than observed in field stars of comparable metallicity, even though its LTE sulphur abundance is in line with abundances of field stars. Moreover the LTE sulphur abundance is consistent only with the abundance of another alpha-element, Mg, in the same star, while the low NLTE value is consistent with Si and Ca. The S abundances in our sample of stars in clusters imply that the clusters are chemically homogeneous for S within 0.05 dex.

Dual role of conditioner CaO in product distributions and sulfur transformation during sewage sludge pyrolysis

Product distributions and sulfur transformation during sewage sludge pyrolysis are essential to subsequent thermal disposal process, both of which are strongly affected by calcium-based compounds. Considering that lime (CaO) is widely applied in sludge conditioning pre-treatment, this study investigated the dual role of conditioner CaO in sludge pyrolysis behavior and sulfur evolution at the temperature range of 873–1273K. Specific compositions in three phases, such as solid residual, tar and gas, were also determined to further clarify the mechanisms involved. According to the results, conditioner CaO increased the fraction of ash and more stable organics in sludge particles, which contributed to higher yield of char comprising lots of carbon and hydrogen. The ring-opening of aromatic hydrocarbons followed by addition reaction of H2O in solid phase facilitated H2 and CO generation, leaving a large number of COH and CO in char. Meanwhile, conditioner CaO catalyzed tar cracking, further increasing the productions of H2 and CO. More interestingly, residual calcium was still capable of fixing sulfur in solid product. Raw sludge matrix prevented sulfur releasing mainly through cyclization reactions, and the relative ratio of char-S only accounted for less than 50%. Correspondingly, most of SO2, CS2, C2H6S2, H2S, COS, and CH4S were emitted. In contrast, char-S yields reached up to 92.8% mainly through forming thermal stable sulfide and sulfate promoted by conditioner CaO, which drove down the final production of sulfurous gases. These indicate that reusing conditioner CaO is a promising strategy for increasing combustible gases and char yields efficiently and reducing the formation of polluting S-containing gases dramatically.

High-pressure studies of palladium and platinum thioether macrocyclic dihalide complexes.

The mononuclear macrocyclic Pd(II) complex cis-[PdCl2([9]aneS3)] ([9]aneS3 = 1,4,7-trithiacyclo-nonane) converts at 44 kbar into an intensely coloured chain polymer exhibiting distorted octahedral coordination at the metal centre and an unprecedented [1233] conformation for the thioether ligand. The evolution of an intramolecular axial sulfur-metal interaction and an intermolecular equatorial sulfur-metal interaction is central to these changes. High-pressure crystallographic experiments have also been undertaken on the related complexes [PtCl2([9]aneS3)], [PdBr2([9]aneS3)], [PtBr2([9]aneS3)], [PdI2([9]aneS3)] and [PtI2([9]aneS3)] in order to establish the effects of changing the halide ligands and the metal centre on the behaviour of these complexes under pressure. While all complexes undergo contraction of the various interaction distances with increasing pressure, only [PdCl2([9]aneS3)] undergoes a phase change. Pressure-induced I...I interactions were observed for [PdI2([9]aneS3)] and [PtI2([9]aneS3)] at 19 kbar, but the corresponding Br...Br interactions in [PdBr2([9]aneS3)] and [PtBr2([9]aneS3)] only become significant at much higher pressure (58 kbar). Accompanying density functional theory (DFT) calculations have yielded interaction energies and bond orders for the sulfur-metal interactions.

Sulfur evolution in chemical looping combustion of coal with MnFe2O4 oxygen carrier

Chemical looping combustion (CLC) of coal has gained increasing attention as a novel combustion technology for its advantages in CO2 capture. Sulfur evolution from coal causes great harm from either the CLC operational or environmental perspective. In this research, a combined MnFe2O4 oxygen carrier (OC) was synthesized and its reaction with a typical Chinese high sulfur coal, Liuzhi (LZ) bituminous coal, was performed in a thermogravimetric analyzer (TGA)-Fourier transform infrared (FT-IR) spectrometer. Evolution of sulfur species during reaction of LZ coal with MnFe2O4 OC was systematically investigated through experimental means combined with thermodynamic simulation. TGA-FTIR analysis of the LZ reaction with MnFe2O4 indicated MnFe2O4 exhibited the desired superior reactivity compared to the single reference oxides Mn3O4 or Fe2O3, and SO2 produced was mainly related to oxidization of H2S by MnFe2O4. Experimental analysis of the LZ coal reaction with MnFe2O4, including X-ray diffraction and X-ray photoelectron spectroscopy analysis, verified that the main reduced counterparts of MnFe2O4 were Fe3O4 and MnO, in good agreement with the related thermodynamic simulation. The obtained MnO was beneficial to stabilize the reduced MnFe2O4 and avoid serious sintering, although the oxygen in MnO was not fully utilized. Meanwhile, most sulfur present in LZ coal was converted to solid MnS during LZ reaction with MnFe2O4, which was further oxidized to MnSO4. Finally, the formation of both MnS and such manganese silicates as Mn2SiO4 and MnSiO3 should be addressed to ensure the full regeneration of the reduced MnFe2O4.

Simulation of a New Chemical-Looping Combustion Process without Sulfur Evolution Based on Ca-Based Oxygen Carrier

Abstract Calcium sulfate (CaSO4) is a promising oxygen carrier for chemical-looping combustion system. The release of sulfurous gas in the circulating of Ca-based oxygen carrier is a crucial problem. In this paper, it is found that the released amount of sulfurous gas is greatly affected by the partial pressure of reductive gas. If the partial pressure of the mixed reductive gases, composed of H2 and CO, maintains higher than 40 kPa, the sulfurous gas can be completely eliminated even at the reacting temperature higher than 1,000°C. Therefore, a new chemical-looping combustion system based on CaSO4 and NiO oxygen carrier, without any sulfur evolution, is simulated using Aspen Plus software. In the system, the syngas is generated from the steam gasification of coal and reacts with CaSO4 and NiO consecutively. The sulfur release occurred in the circulating of Ca-based oxygen carriers can be prevented because the concentrations of CO and H2 keep higher than 45% in the presence of Ca-based oxygen carriers. The suitable operating regime, in which auto-thermally operating of the system, zero-sulfur release and easy sequestration of CO2 from the flue gas are realized, is proposed in this paper. The effects of fuel reactor temperature, air reactor temperature and the recycle rate of oxygen carrier on the released heat from the system and the concentration of CO2 and H2O are also studied in the paper.

Desulphurisation and Inclusion Behaviour of Stainless Steel Refining by Using CaO–Al2O3 Based Slag at Low Sulphur Levels

The deep desulphurisation behaviour and steel cleanliness of stainless steel refining in the low sulphur content period (below 45 ppm [%S]) by using the current lime-fluorspar based slag and an optimized lime-alumina slag have been studied and compared. The desulphurisation effect was discussed based on the calculated sulphide capacity of slags and the equilibrated sulphur distribution ratio between the slag and steel. The sulphur evolution during the treatment was predicted with a previously developed kinetic model. The influence of slag chemistry on the compositional evolution of the steel and inclusions was discussed through thermodynamic considerations with respect to deoxidation and desulphurisation reactions. The sulphur content in the inclusions was predicted using the dissolved sulphur in the steel and their oxide chemistry. An equivalent steel cleanliness and desulphurisation effect was obtained with lime-alumina based slag as with lime-fluorspar based slag both in laboratory and industrial tests for low sulphur content stainless refining.

TGA-FTIR investigation of chemical looping combustion by coal with CoFe2O4 combined oxygen carrier

Chemical looping combustion (CLC) of coal has received great interest for its pronounced advantage in CO2 capture. Sulfur evolution from coal causes great harm to CLC system. In this research, combined CoFe2O4 oxygen carrier (OC) was synthesized and its reaction with a typical Chinese high sulfur coal as Liuzhi (LZ) coal was investigated with the research focus on the sulfur evolution from LZ coal during its reaction with CoFe2O4 OC. Analysis of LZ coal reaction with CoFe2O4 OC through thermogravimetric analyzer (TGA)-Fourier transform infrared (FTIR) indicated that CoFe2O4 owned the desired reaction superiority over its reference oxide CoO or Fe2O3, and SO2 produced was mainly related to oxidization of H2S with CoFe2O4. Field emission scanning electron microscopy/energy-dispersive X-ray spectrometry (FESEM-EDX) and X-ray diffraction (XRD) analysis of the solid product from LZ coal reaction with CoFe2O4 indicated that CoFe2O4 were mainly reduced to Fe3O4 and Co, as verified by the related thermodynamic simulation. But most of sulfur present in LZ coal was converted to solid Co3S4 during LZ coal reaction with CoFe2O4. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis of various carbon functional groups distributed in the solid product of LZ reaction with CoFe2O4 revealed that CC or CH functional group was the lowest reactive to limit the full conversion of LZ coal on the atomic scale. Finally, such sulfides as CoS and Co3S4 and various silicates, including Co2SiO4 and Fe2SiO4, should be well addressed and separated during reaction of LZ with CoFe2O4 to ensure the full regeneration of the reduced CoFe2O4.

Galactic chemical evolution of sulphur

Context. The Galactic chemical evolution of sulphur is still under debate. At low metallicities some studies find no correlation between [S/Fe] and [Fe/H], others find [S/Fe] increasing towards lower metallicities, and still others find a combination of the two. Each scenario has different implications for the Galactic chemical evolution of sulphur. Aims. To contribute to the discussion on the Galactic chemical evolution of sulphur by deriving sulphur abundances from non-LTE insensitive spectral diagnostics in Disk and Halo stars with homogeneously determined stellar parameters. Methods. We derive Teff from photometric colours, logg from stellar isochrones and Bayesian estimation, and [Fe/H] and [S/Fe] from spectrum synthesis. We derive [S/Fe] from the [S i] 1082 nm line in 39 mostly cool and metal-poor giants, using 1D LTE MARCS model atmospheres to model our high-resolution NIR spectra obtained with the VLT, NOT and Gemini South telescopes. Results. We derive homogeneous stellar parameters for 29 stars. Our results argue for a chemical evolution of sulphur that is typical for alpha-elements, contrary to some previous studies. Our abundances are systematically higher by about 0.1 dex in comparison to other studies that arrived at similar conclusions using other sulphur diagnostics. Conclusions. We find the [S i] line to be a valuable diagnostic of sulphur abundances in cool giants down to [Fe/H] ~ -2.3. We argue that a homogeneous determination of stellar parameters is necessary, since the derived abundances are sensitive to them. Our results ([S/Fe]) show reasonable agreement with predictions of contemporary models of Galactic chemical evolution. In these models sulphur is predominantly created in massive stars by oxygen burning, and ejected in the ISM during Type II SNe explosions. Systematic differences with previous studies likely fall within modelling uncertainties.

Evolution of Organic Sulfur in the Thermal Upgrading Process of Shengli Lignite

Thermal upgrading is a promising way to improve the quality and broaden the range of use of lignite. This paper investigated the characteristics of organic sulfur evolution in a Chinese lignite from Shengli coalfield in the process of thermal upgrading by a fluidized-bed reactor under different atmospheres. The results showed that 5 min of fluidization of feed coal within the temperature range from 200 to 500 °C was capable to obtain a preferable upgraded coal with the increase of the calorific value and the decrease of the moisture. The removal of total sulfur via thermal upgrading, reaching the top at about 60%, was attributed to the evolution of organic sulfur. X-ray photoelectron spectroscopy results showed that aliphatic, aromatic and thiophene, and sulfone sulfur were the major organic sulfur species in Shengli lignite (SL). Aliphatic sulfur was the most unstable organic sulfur and began to release at 200 °C. Aromatic sulfur was found to release at 300 °C. Thiophene sulfur was most stable and could ...

Chemical Looping Combustion of Petroleum Coke with CuFe2O4 as Oxygen Carrier

AbstractUtilizing petroleum coke as fuel in an efficient and environmentally friendly way is a great challenge. Within the technological framework of chemical looping combustion, the reaction of the oxygen carrier CuFe2O4 with a typical high‐sulfur petroleum coke (designated as JS) was performed, focusing on the conversion of the JS coke, the oxygen transfer from CuFe2O4, and the reaction characteristics involved. Simultaneously, the evolution of sulfur and minerals present in JS was also considered. Thermogravimetric analysis of the reaction of CuFe2O4 with JS demonstrated the reaction superiority of CuFe2O4, with its reactivity being close to that of CuO. The preferred CuFe2O4 oxygen excess number Φ for JS conversion was determined as unity. Furthermore, both the experimental means, including Fourier transform infrared spectroscopy, field scanning electron microscopy/energy‐dispersive X‐ray spectrometry and X‐ray diffraction analysis, and the thermodynamic simulation of the reaction of CuFe2O4 with JS indicated that the main reduced counterparts of CuFe2O4 were Cu and Fe3O4. Most of the organic sulfur dominant in JS coke reacted with the reduced CuFe2O4 to form Cu2S, and the side product Fe2SiO4 should also be noted for its detrimental effect on the reactivity of CuFe2O4.

Sulfur evolution of the 1991 Pinatubo magmas based on apatite

Using electron microprobe (EMP) and laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to collect major and rare-earth elements (REE), respectively, from apatites from the 1991 Mt. Pinatubo juvenile eruption products, we have determined that two statistically distinct populations of apatite exist. One population crystallized from the juvenile basaltic melt (basalt apatites) and the other population crystallized from the main dacitic magma body (silicic apatites). Both populations contain high-S apatites (>0.7wt.% SO3). Apatite has previously been shown to be a potential monitor for magmatic sulfur contents via numerous proposed coupled substitutions of P5+ for S6+. However, simple apatite/melt partitioning cannot account for high-S silicic apatites, which grew from a silicic melt with an apparent maximum S concentration of ~80ppm. Disparate apatite morphology (i.e. skeletal and acicular for basalt apatites and euhedral for silicic apatites) as well as compositional evidence reveal that high-S silicic apatites were not inherited from the juvenile basalt during mingling/mixing prior to eruption. Sulfur gain from neighboring anhydrite phenocrysts can also be ruled-out as a source of high sulfur. EMP sulfur mapping of silicic apatites shows highly irregular patterns of sulfur enrichment that do not correspond with adjacent anhydrite and can be found within apatites hosted by other minerals (e.g. hornblende and Fe–Ti oxides). With these data in mind, we propose high-S silicic apatites from Pinatubo and other sulfur-rich systems achieved elevated sulfur concentrations during high sulfur fluxing events that originated from underplated basalt during degassing of a SO2-rich fluid phase. That basalts were indeed sulfur rich and oxidized is here indicated by high S contents of apatites growing in basalt. The predominant location of S-rich areas of silicic apatite is crystal interiors of apatite inclusions in other mineral phases, while large apatite microphenocrysts surrounded by groundmass glass have low sulfur contents. This is evidence for placing sulfur-fluxing periods long before events that ultimately led to the 1991 eruption.

XANES Investigation on Sulfur Evolution during Victorian Brown Coal Char Gasification in Oxy-Fuel Combustion Mode

This study has clarified the speciation of sulfur in the pyrolysis char of Victorian brown coal and its evolution during char gasification in oxy-fuel combustion. The synchrotron XANES has been used for sulfur speciation. Coal pyrolysis was first carried out in a lab-scale drop-tube furnace (DTF). The resulting char was then size-segregated and gasified in O2/N2 and O2/CO2 gases to examine the evolution of sulfur as a function of particle residence time and oxygen fraction in bulk gas. The results indicate that thiophenic sulfur is the predominant form for sulfur in raw coal and its pyrolysis char. The substitution of O2/CO2 for O2/N2 slightly increased the rate of mass loss of sulfur upon char gasification, due to thermodynamically viable routes for the decomposition of thiophene into COS and CS2 in CO2, rather than HS in N2. For the small char particle rich in highly reactive alkali and alkaline earth metals, the extra loss of sulfur in CO2 was readily stabilized into sulfate on the local char surface at a relatively long residence time of about 1.6 s in the DTF. The participation of inherent oxygen in char is essential for the sulfation reaction; however, this was inhibited by introducing oxygen into the bulk gas. The rapidly decomposed sulfur present in gaseous oxides preferentially diffused out of the char surface into the bulk gas. The uneven distribution of alkali and alkaline earth metals with respect to char particle size is influential in affecting the sulfation extent on the char surface.

Generation of ultra-clean fuel from Victorian brown coal – Synchrotron XANES study on the evolution of sulphur in Victorian brown coal upon hydrothermal upgrading treatment and thermal pyrolysis

This paper reported the speciation of sulphur in two parent Victorian brown coals and their upgraded derivatives through the use of direct, non-destructive synchrotron-based S K-edge XANES. Victorian brown coal is the single largest source for power generation in Victoria, Australia. To date little has been known about its sulphur speciation. The results here demonstrated the predominance of organosulphur in the forms of thiophene and mono-/poly-sulphide in Victorian brown coals, irrespective of coal mining location and particle size. The sulphidic sulphur in the raw coal was readily cleaved and released as gas upon hydrothermal leaching in citric acid at the temperatures up to 200°C. The use of concentrated 5M nitric acid for acid leaching caused the oxidation of a portion of sulphide and thiophene into organic sulphate which bears an XANES position between inorganic sulphate and sulphone. Thermal pyrolysis is more effective in reducing sulphur in char, resulting in an overall sulphur content as low as 0.1wt.% for the char produced at 800°C. This is due to the rapid decomposition of organic sulphide commencing at 400°C. The mobilisation rate of thiophene associated with aromatic carbon varied greatly with coal type. For the sulphur released upon thermal pyrolysis, a portion of it was also captured by inherent alkali and alkaline earth metals forming sulphate particularly in the 800°C char. A prior acid washing of coal favoured eliminating the formation of inorganic sulphate in the resulting char sample. However, the remaining sulphur in the coal was evolved to distinct structure that has a rather stronger resonant scattering, or in a formation of acid-insoluble sulphate caused by the oxidation/reformation of organic matrix.

Sulphur abundances in halo giants from the [S ı] line at 1082 nm and the S ı triplet around 1045 nm

Context. It is still debated whether or not the Galactic chemical evolution of sulphur in the halo follows the flat trend with [Fe/H] that is ascribed to the result of explosive nucleosynthesis in type II SNe. It has been suggested that the disagreement between different investigations of sulphur abundances in halo stars might be owing to problems with the diagnostics used, that a new production source of sulphur might be needed in the early Universe, like hypernovae, or that the deposition of supernova ejecta into the interstellar medium is time-delayed.

Sulfur-bearing Magmatic Accessory Minerals

Research Article| January 01, 2011 Sulfur-bearing Magmatic Accessory Minerals Fleurice Parat; Fleurice Parat Géosciences Montpellier - Université Montpellier 2, Place E. Bataillon, 34095 Montpellier cedex 5. France and Mineralogie-Geochemie, Institut für Geowissenschaften, Albertstr. 23b, 79104 Freiburg, Germany, Fleurice.Parat@gm.univ-montp2.fr Search for other works by this author on: GSW Google Scholar François Holtz; François Holtz Institut für Mineralogie, Callinstr. 3, Leibniz Universität, Hannover 30167, Germany Search for other works by this author on: GSW Google Scholar Martin J. Streck Martin J. Streck Department of Geology, Portland State University, Portland, Oregon 97207-0751, U.S.A. Search for other works by this author on: GSW Google Scholar Reviews in Mineralogy and Geochemistry (2011) 73 (1): 285–314. https://doi.org/10.2138/rmg.2011.73.10 Article history first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Fleurice Parat, François Holtz, Martin J. Streck; Sulfur-bearing Magmatic Accessory Minerals. Reviews in Mineralogy and Geochemistry 2011;; 73 (1): 285–314. doi: https://doi.org/10.2138/rmg.2011.73.10 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyReviews in Mineralogy and Geochemistry Search Advanced Search Almost all magmas contain sulfide- or sulfate-bearing phases. In most natural samples the sulfur-bearing phase is a sulfide, which typically is pyrrhotite (Fe1−xS) or pyrite (FeS2) although chalcopyrite (CuFeS2), pentlandite ((Fe,Ni)9S8), sphalerite (ZnS) or molybdenite (MoS2) may be present as well. Sulfate minerals are rare at magmatic conditions, and anhydrite (CaSO4) is the most common. Other magmatic SO4-bearing minerals include the sodalite group minerals (haüyne simplified formula: (Na,Ca)4–8(Al6Si6(O,S)24)(SO4,Cl)1–2), scapolite minerals (silvialite:... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Thermodynamic investigation into carbon deposition and sulfur evolution in a Ca-based chemical-looping combustion system

Chemical-looping combustion is a promising technology that concentrates CO 2 and separates it during combustion. In this study, both the carbon deposition and sulfur evolution in the reduction of a calcium sulfate (CaSO 4) oxygen carrier with a typical syngas were investigated using thermodynamic simulations. The effects of reaction temperature, operating pressure and the oxygen ratio number (defined in this paper) on the amount of deposited carbon and released sulfurous gases are discussed. A reaction temperature from 750 to 950 °C, an operating pressure from 1 to 15 bars and an oxygen ratio number between 0.4 and 0.8 were determined to be the most favorable operating conditions. In addition, the amounts of released sulfurous gases were found to be largely dependent on the partial pressures of H 2 and CO based on the thermo-gravimetric analyzer (TGA) tests. When the partial pressure of H 2 or CO was above 40 kPa, the release of sulfurous gases could be prevented in the reaction between CaSO 4 and syngas, even if the reaction temperature was as high as 1000 °C. The XRD profiles of the products also demonstrated that the mole fraction of CaS in the products increased gradually with an increasing partial pressure of H 2 or CO, until the products were almost pure CaS.

Sulfur in Magmas

Research Article| April 01, 2010 Sulfur in Magmas Nicole Métrich; Nicole Métrich 1Laboratoire Pierre Süe/SIS2M, CNRS-CEA, CE-Saclay, France Search for other works by this author on: GSW Google Scholar Charles W. Mandeville Charles W. Mandeville 2American Museum of Natural History Central Park West at 79th Street, New York, NY 10024, USA E-mail: nicole.metrich@cea.fr; cmandy@amnh.org Search for other works by this author on: GSW Google Scholar Author and Article Information Nicole Métrich 1Laboratoire Pierre Süe/SIS2M, CNRS-CEA, CE-Saclay, France Charles W. Mandeville 2American Museum of Natural History Central Park West at 79th Street, New York, NY 10024, USA E-mail: nicole.metrich@cea.fr; cmandy@amnh.org Publisher: Mineralogical Society of America First Online: 09 Mar 2017 Online ISSN: 1811-5217 Print ISSN: 1811-5209 © 2010 by the Mineralogical Society of America Elements (2010) 6 (2): 81–86. https://doi.org/10.2113/gselements.6.2.81 Article history First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Nicole Métrich, Charles W. Mandeville; Sulfur in Magmas. Elements 2010;; 6 (2): 81–86. doi: https://doi.org/10.2113/gselements.6.2.81 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyElements Search Advanced Search Abstract Sulfur is a ubiquitous element whose variable valence states (S2−, S0, S4+, S6+) allow it to participate in a wide variety of geochemical and biogeochemical processes. Depending on its redox state and controlling species, sulfur dissolved in magma may be fractionated into a water-rich phase and sulfur-bearing minerals. Retrieving information on the original sulfur abundance and isotopic signature of a magma is challenging and requires deciphering the different processes that may have operated during its evolution en route to the surface. Advances made in thermodynamic modeling, experimentation on sulfur solubility and diffusion in silicate melts, and microanalytical techniques for probing sulfur's speciation and isotopic signature at the micrometer scale are providing an outstanding picture of sulfur evolution in magmas. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.