Presence Of Iron Sulfide Research Articles

ВПЛИВ МІГРАЦІЇ ФЛЮЇДІВ НА МАГНІТНУ МІНЕРАЛОГІЮ ҐРУНТІВ

Background. The war in Ukraine arises the urgent need to intensify hydrocarbon production on its own territory in order to maintain and develop the country's energy independence. The effectiveness, low cost and relevance of the involvement are demonstrated by magnetic methods of studies of the near surface geological section and the soil for the oil and gas prospecting. Methods. The methodology of magnetic studies for the hydrocarbon prospecting is based on the methods of studying the environmental magnetism and soil, precision magnetic survey of natural systems and authigenic models of changes in magnetic mineralogy under the influence of hydrocarbon fluid migration. Results. The crucial aim is to distinguish the sources of the formation of the magnetic minerals. In most cases, soils contain minerals of natural pedogenic origin, authigenic secondary magnetic minerals, and sometimes detrital fine-coarse magnetic phases. For Ukraine, magnetite, maghemite, hematite, and goethite are the most common magnetic minerals of soils of the pedogenic origin. At the same time, the experience of conducting magnetic mineralogical analyzes of soils in the territories of oil and gas deposits indicates the presence of iron sulfides. First of all, monoclinic pyrrhotite is identified. The soils also contain accompanying hexagonal pyrrhotite, pyrite, and greigite. The results of thermomagnetic analyzes and hysteresis loops of soil samples collected at the territories of hydrocarbon deposits are presented and their mineral composition is analyzed. Conclusions. The results of the study of the impact of hydrocarbon fluid migration (microseepage) on the change in the mineral composition of soils indicate significant informativeness and the perspective of introducing the method into the complex of geological exploration works at various stages. Authigenic changes of magnetic minerals in the near surface geological section and soil, as well as natural and anthropogenic accumulation of hydrocarbon products in soils, cause changes in magnetic properties and form magnetic field anomalies.

Organic-rich bimineralic ooids record biological processes in Shark Bay, Western Australia.

Marine ooids have formed in microbially colonized environments for billions of years, but the microbial contributions to mineral formation in ooids continue to be debated. Here we provide evidence of these contributions in ooids from Carbla Beach, Shark Bay, Western Australia. Dark 100-240 μm diameter ooids from Carbla Beach contain two different carbonate minerals. These ooids have 50-100 μm-diameter dark nuclei that contain aragonite, amorphous iron sulfide, detrital aluminosilicate grains and organic matter, and 10-20 μm-thick layers of high-Mg calcite that separate nuclei from aragonitic outer cortices. Raman spectroscopy indicates organic enrichments in the nuclei and high-Mg calcite layers. Synchrotron-based microfocused X-ray fluorescence mapping reveals high-Mg calcite layers and the presence of iron sulfides and detrital grains in the peloidal nuclei. Iron sulfide grains within the nuclei indicate past sulfate reduction in the presence of iron. The preservation of organic signals in and around high-Mg calcite layers and the absence of iron sulfide suggest that organics stabilized high-Mg calcite under less sulfidic conditions. Aragonitic cortices that surround the nuclei and Mg-calcite layers do not preserve microporosity, iron sulfide minerals nor organic enrichments, indicating growth under more oxidizing conditions. These morphological, compositional, and mineralogical signals of microbial processes in dark ooids from Shark Bay, Western Australia, record the formation of ooid nuclei and the accretion of magnesium-rich cortical layers in benthic, reducing, microbially colonized areas.

Oxidation–reduction reactions and hydrogenation of steels of different structures in chloride-acetate solutions in the presence of iron sulfides

Abstract The influence of iron sulfide on the rate of cathodic and anodic processes of steels with ferrite, perlite and ferrite perlite structure was shown. It was established that the hydrogenation and corrosion rate of steels with different structures depends not only its structure, but also the nature of sulfide-containing products of corrosion. The well-known scheme of the influence of hydrogen sulfide on the processes of corrosion and hydrogenation of steel was supplemented by reactions of formation iron sulfides. They can affect the rate of recombination of hydrogen atoms and, respectively, its molation and absorption by metals.

Sulfate-Reducing Bacteria in Patients Undergoing Fixed Orthodontic Treatment

ObjectivesThe oral microbiological environment may be implicated in the corrosion of orthodontic metals. This study aimed to examine the prevalence of sulfate-reducing bacteria (SRB) in orthodontic patients undergoing fixed appliance treatment. MethodsSixty-nine orthodontic and 69 healthy non-orthodontic participants were enrolled in the study. Supragingival and subgingivaloral biofilm were collected and tested for the presence of SRB. The DNA extraction, polymerase chain reaction (PCR), and 16sRNA Sanger sequencing method was performed from the SRB-positive samples. The sequenced PCR products were analysed and compared with databases to identify the bacterial genus. ResultsAmongst 69 orthodontic patients, characteristic black precipitates developed in 14, indicating the presence of iron sulfides which demonstrates the likelihood of SRB. Alternatively, 2 out of 69 showed the presence of SRB in healthy non-orthodontic participants (controls). Desulfovibrio spp was confirmed by analyses of 16sRNA sequencing, which revealed that the SRB prevalence was 20% in the examined participants with orthodontic appliances. ConclusionsThe prevalence of SRB was found to be significantly higher amongst orthodontic patients compared to non-orthodontic participants. Presence of stainless steel in the oral environment may have facilitated the colonisation of SRB.

Coal mining pyritic waste in Fenton-like processes: Raw and purified catalysts in Reactive Blue 21 dye discoloration

Raw pyritic waste (RPW) from South Brazilian coal deposits and pure pyritic waste (PPW) were used as catalysts for organic dyes discoloration. Samples were characterized for their chemical, morphological, and structural properties. There was a significant content of Fe and S in both samples from the presence of iron sulfide. The average particle size is 10.9 μm for RPW and 7.4 μm for PPW, demonstrating that the beneficiation process could remove the larger quartz particles, interfered in the distribution, and average particle size. Smaller particle sizes promoted a larger surface area for the PPW. The influence of the pyritic waste in dosage, H2O2 concentration, and pH was evaluated, obtaining discoloration values above 95% for 0.5 g/L of pyritic waste, 2 g/L of H2O2, and pH 4.3 for both pyritic wastes. The degradation kinetics of the Reactive Blue 21 using the raw pyritic waste obtained a dye concentration removal above 93% in 90 min, with an iron release of 5.4 mg/L into the solution. Using PPW, the dye concentration removal was over 92% in 40 min, with the iron release of 15.5 mg/L into the solution. Discoloration rate for the PPW sample is 7 times greater than the rate obtained for RPW, indicating a faster decay rate for the purified sample. A decrease in discoloration efficiency is observed for PPW after 6 cycles of use, due to the higher concentration of iron leached into the medium. From the results, it was concluded that the raw pyritic waste has excellent potential for use as a catalyst for Fenton reaction, especially for dye-containing water discoloration, thus demonstrating the excellent applicability potential of pyritc waste in the degradation of organic pollutants in wastewater.

Magnetic Mineralogical Approach for the Exploration of Gas Hydrates in the Bay of Bengal

AbstractWe evaluate the environmental magnetic, geochemical, and sedimentological records from three sediment cores from potential methane‐hydrate bearing sites to unravel linkages between sedimentation, shale tectonics, magnetite enrichment, diagenesis, and gas hydrate formation in the Krishna‐Godavari basin. Based on downcore rock magnetic variations, four sedimentary magnetic property zones (I–IV) are demarcated. A uniform band of enhanced magnetic susceptibility (zone III) appears to reflect a period of high‐sedimentation events in the Krishna‐Godavari basin. Highly pressurized sedimentary strata developed as a result of increased sedimentation that triggered the development of a fault system that provided conduits for upward methane migration to enter the gas hydrate stability zone, leading to the formation of gas hydrate deposits that potentially seal the fault system. Magnetic susceptibility fluctuations and the presence of iron sulfides in a magnetically enhanced zone suggest that fault system growth facilitated episodic methane venting from deeper sources that led to multiple methane seepage events. Pyrite formation along sediment fractures resulted in diagenetic depletion of magnetic signals and potentially indicates paleo sulfate‐methane transition zone positions. We demonstrate that a close correlation between magnetic susceptibility and chromium reducible sulfur concentration can be used as a proxy to constrain paleomethane seepage events. Our findings suggest that the interplay between higher sedimentation events and shale tectonism facilitated fluid/gas migration and trapping and the development of the gas hydrate system in the Krishna‐Godavari basin. The proposed magnetic mineralogical approach has wider scope to constrain the understanding of gas hydrate systems in marine sediments.

Utilization of X-ray computed micro-tomography to evaluate iron sulphide distribution in roofing slates

Slate is a traditional stone product that has long been used for roofing widely around the world. The presence of iron sulphides is one of the most significant factors affecting roofing slate resistance to weathering and, therefore, the quality of slates and their use in construction. Iron sulphide oxidation is the main process of roofing slate degradation. Qualitative and quantitative analyses to determine iron sulphides in roofing slates are usually conducted using transmitted and reflected light microscopy, and X-ray diffraction techniques. However, this paper presents X-ray computed micro-tomography as a new laboratory method in this field, which also allows for 3D visualization and analysis of iron sulphide distribution in roofing slates. It also discusses some technical limits of this technique and tomographic scan interpretation pitfalls. The results obtained by tomographic observations were subsequently verified by optical microscopy, X-ray powder diffraction and scanning electron microscopy, as well as energy-dispersive X-ray spectroscopy analyses. Spanish slate from the Ordovician Luarca Formation and Culm slate from the Moravice Formation in the Czech Republic are both characterized by low to extremely low iron sulphide content, and for this reason were selected for this study.

An Efficient and Robust Surface-Modified Iron Electrode for Oxygen Evolution in Alkaline Media

The efficiency and cost of water electrolysis systems and rechargeable metal-air batteries can be improved by reducing the overpotential losses at the oxygen evolution electrode in alkaline medium. [1] Therefore, we seek inexpensive, efficient and durable electrocatalysts for the oxygen evolution reaction in alkaline medium. Transition metal oxides supported on nickel substrates have been the work-horse catalysts of industrial alkaline water electrolysis. But the cost added by nickel-based substrates can also be quite significant, and its replacement by less expensive materials is much desired. In our earlier study we had showed for the first-time that porous iron-sintered substrates modified by surface treatment using nickel can act as remarkably stable electrode when anodically polarized and also present a highly active electrocatalytic surface for the oxygen evolution reaction. [2] On these nickel modified sintered iron electrodes (NSI) we found an overpotential of 230 mV at 10 mA/cm2 (Figure 1 a).In our quest for further improvements we have studied the effect of additive materials that can enhance the activity of NSI electrodes. Herein, we report a remarkably efficient and highly durable nickel modified iron electrode that has an iron sulfide additive (NSI-FeS) for oxygen evolution reaction. Such an electrode was prepared through a four-step process: (1) sintering of iron substrate along with 1 wt% of iron sulfide, (2) electrochemical oxidation of as-sintered electrode from open circuit potential to -0.6 V vs mercury-mercuric oxide electrode in 30 w/v % potassium hydroxide aqueous solution, (3) application of nickel coating and (4) calcination of nickel coating at 200o C. As-prepared NSI-FeS electrode exhibits an overpotential of ~200 mV to achieve 10 mA/cm2 current density with a Tafel slope of 46 mV/decade (Figure 1 a). The high activity for oxygen evolution may result from increased surface area obtained through electrochemical oxidation of iron substrate in presence of iron sulfide. The same electrode exhibits a highly stable overpotential for 1500 hours of testing at 10 mA/cm2 with an average change as small as 1 mV/1000 hour (Figure 1 b). Physical characterization methods such as XRD and XPS have been used to probe surface composition of the electrodes, and measurements for electrochemically active surface area were conducted through electrochemical impedance spectroscopy.

Corrosion inhibition by the trace amount of sulphide ion in CO2-saturated brine solutions

By accurately controlling the concentration of sulphide ion in CO2-saturated solutions, it was demonstrated that the corrosion behaviour of mild steel was sensitive to the trace amount of sulphide ion additions. An obvious inhibition effect on cathodic reactions was observed at an extremely low level of sulphide ion, while a detrimental effect on corrosion was gradually emerged as its dosage increased higher than 0.5 mg L−1. These positive and negative synergy effects would be strengthened after immersing for longer time. The sensitivity of CO2 corrosion to sulphide ion was attributed to the modification of surface properties by the presence of iron sulphides.

The influence of pH and reaction time on the formation of FeSe2 upon selenite reduction by nano-sized pyrite-greigite

Abstract The influence of pH and reaction time on the formation of FeSe2 by reductive precipitation of Se(IV) with nano-sized pyrite-greigite was investigated. Reductive precipitation is an effective method of attenuating the mobility of 79Se, which is foreseen to be a dangerous radioisotope for the geological disposal of high-level radioactive waste (HLW). The results indicated that Se(0)was formed at pH <4.05, whereas, at pH > 6.07, considerable amount of FeSe2 was formed along with Se(0). These observations are in agreement with the thermodynamic predictions reported in this work. Furthermore, the formation of FeSe2 was found to continue by increasing the reaction time, indicating that the Se(0) formed in the early reaction stage is gradually transformed to FeSe2 upon the depletion of aqueous Se(IV). Since FeSe2 has a stronger reactivity than pyrite, it was proposed that greigite, rather than pyrite, was responsible for the formation of FeSe2. The findings in this study are of interest for key geochemical processes governing the mobility of toxic 79Se in the environment in presence of iron sulfides.

The effect of an organic pentasulfide EP additive in turning and milling operations

Because a cutting fluid could be equally used for different cutting operations, this study proposed to investigate the behavior of a well-known extreme-pressure additive (pentasulfide) in both turning and milling operations of a steel workpiece. The experimental approach is based on the coupling of mechanical tests (turning, milling, and tribological tests) with physico-chemical characterizations (Auger Electron Spectroscopy and X-Ray Photoelectron Spectroscopy) of the friction surfaces (chip and tool). In the case of milling, it was shown that the presence of a pentasulfide additive has a beneficial effect on the specific cutting energy (kc) and flank wear (Vb). These results are correlated with the presence of iron sulfides (FeS and FeS2) on the flank face of the cutter mill and on the chip face in contact with the mill. No such additive effects are found in case of turning. A lubrication model is proposed for the case of milling based on an indirect lubrication of the tool/workpiece and tool/chip contacts due to the transfer of iron and its reaction with sulfur compounds to produce iron sulfides. Because milling is a discontinuous cutting process, this lubrication mechanism is much more efficient than that observed in turning. Indeed, the tool faces are re-fed iron sulfides each time they leave the workpiece.

Iron removal from waterlogged wood: Extraction by electrophoresis and chemical treatments

The presence of iron oxides (lepidocrocite, goethite) in archeological wood may result in a degradation of the wood matrix. Extraction of these iron oxides is largely dependent on their solubility. In this study, balsa wood samples were impregnated with iron oxides to test extraction treatments. Additionally, archeological wood samples were also examined to determine treatment efficiency. Electrophoresis and simple immersion treatments were performed using various chemical solutions: a neutral and a conductive substance (potassium nitrate), an acid (acetic acid), three alkaline chelating agents (tri-ammonium and tri-sodium citrate and sodium oxalate), three acidic and slightly acidic chelating agents (ethylenediaminetetraacetic acid (EDTA), citric acid, and oxalic acid), and a reductant (sodium dithionite). Potassium nitrate did not extract sufficient amounts of iron, irrespective of whether the treatment was conducted by electrophoresis or simple immersion; any observable dissolution was attributed to protonation because of the acidic pH around the anode (as low as 3). Dissolution in acetic acid did not extract iron with either treatment. Strong chelating agents improved extraction, and these compounds gave the best results for simple immersion, particularly EDTA. This chemical is well adapted for use on archeological objects because of its chemical properties (stability constant, speciation based on pH). The addition of sodium dithionite to the solution improved dissolution. Even though electrophoresis improved extraction (in particular for tri-ammonium citrate), none of the tested chelating chemicals were suitable for electrophoresis because of a significant increase in temperature as well as high anode corrosion. The presence of iron sulfide in the archeological wood limited the effectiveness of the tested chemicals. A pre-treatment in sodium persulfate was expanded to include oxidized iron sulfide in oxy/hydroxide iron, which improved the extraction rate.

Selenium sorption and isotope fractionation: Iron(III) oxides versus iron(II) sulfides

Sorption and reduction are important processes influencing the environmental mobility and cycling of Se. In this study, we determined the rates of reaction and isotopic fractionations of Se(IV) and Se(VI) during sorption to iron oxides (2-line ferrihydrite, hematite and goethite) and iron sulfides (mackinawite and pyrite) at pH7 and room temperature (22±2°C). More than 80% of aqueous Se(IV) was removed from solution in the presence of the mineral phases, except for hematite where only 40% of aqueous Se(IV) was sorbed. In contrast, less than 20% of aqueous Se(VI) was removed in the mineral suspensions, except for 2-line ferrihydrite where approximately 50% removal was observed. While XANES spectra revealed no change in Se oxidation state when Se(IV) and Se(VI) sorbed to iron oxides, they showed evidence of reduction in the presence of iron sulfides. Selenium isotopic fractionations, expressed as ε82/76Se, were always less than 1‰ in the experiments with iron oxides (mean ε82/76Se: 0.2‰). Fractionations were significantly higher in the experiments with iron sulfides, with ε82/76Se values of up to ~10‰ in the Se(IV)-pyrite system, and a mean ε82/76Se value of 2.3‰ for all sorption experiments with iron sulfides combined. The larger fractionations in the experiments with iron sulfides reflect the chemical reduction of Se(IV) and Se(VI). The highest isotope fractionation observed in the Se(IV)–FeS2 system (9.7‰) is comparable to that previously reported for Se(VI) reduction by green rust (11.1‰).

Microbiologically influenced corrosion of archaeological artefacts: characterisation of iron(II) sulfides by Raman spectroscopy

AbstractArchaeological objects are exposed to the action of micro‐organisms when they lay in a biologically active environment. The presence of iron sulfides in the corrosion system testifies in most cases that the degradation was influenced by sulfate‐reducing bacteria. Iron sulfides and other iron/sulfur‐containing compounds were detected by micro‐Raman spectroscopy in rust layers of archaeological ferrous objects and in wet wooden fragments contaminated by iron, extracted from ancient wrecks. Although mackinawite (FeS) is very reactive towards oxygen, this phase was observed in each sample. Its crystallisation levels and oxidation states could be differentiated. Greigite (Fe3S4) was also identified by means of X‐ray diffraction, used when possible as a complementary analytical tool. Known as the result of the oxidation of mackinawite, greigite was likely to form during the experiments carried out without any protection against air. It was then possible to describe the formation and oxidation processes of iron sulfides in archaeological iron artefacts or in organic materials contaminated by iron. Copyright © 2010 John Wiley & Sons, Ltd.

Modeling vertical excursions of the redox boundary in sediments: Application to deep basins of the Arctic Ocean

A diagenetic reaction‐transport model was used to simulate how the sediment redox boundary migrates in response to persistent or episodic changes in the deposition flux of degradable organic matter and the concentration of oxygen in the overlying bottom water. The position of the redox boundary is represented by the depth of oxygen penetration. The simulations reveal that the position of the redox boundary in organic‐poor sediments, such as those in the deep basins of the Arctic Ocean, is highly sensitive to the flux of organic matter: relatively small and/or brief increases in that flux can cause the redox boundary to migrate rapidly from deep within the sediment to within a few centimeters of the sediment‐water interface. Reoxidation of the sediment column after such an event can take years. Redox fluctuations can redistribute solid‐phase manganese within the sediment column and produce multiple concentration peaks in its depth profile on a decadal time scale. Manganese peaks observed in sediment cores from the deep basins of the Arctic Ocean do not necessarily correspond to the position of the redox boundary during previous climatic periods or reflect historical changes in manganese deposition rates. The model supports the hypothesis that the recent decrease in the Arctic ice cover has increased the flux of organic matter to the seafloor and moved the redox boundary close to the sediment‐water interface. The presence of iron sulfides at depths significantly below the bioturbated layer suggests that either the Arctic sediments have been anoxic for millennia, or iron and sulfate are reduced at these depths by dissolved organic matter diffusing downward from the bioturbation zone.

Substrate characterisation for a subsurface reactive barrier to treat colliery spoil leachate

Subsurface permeable reactive barriers (PRB) have been used to successfully treat acidic mine drainage in Canada and offer great potential for doing the same in the United Kingdom. A PRB for the treatment of colliery spoil leachate from a site near Newcastle upon Tyne, UK, has been designed. The selection of the reactive media to be used is of paramount importance, with particular reference to permeability and reactivity. A number of reactive media mixtures containing varying proportions of cattle slurry screenings, green waste compost, calcite limestone chips and pea gravel were prepared and their respective permeabilities and reactivities were investigated. Media mixtures containing 50% 10 mm grade calcite limestone chips showed better alkalinity addition and metals removal than a blank containing 50% pea gravel. A media mixture containing 50% limestone chips and 50% green waste compost showed a 24 h period to achieve maximum addition of alkalinity and maximum removal of acidity and metals. Mixtures containing 25% green waste compost and 25% slurry screenings achieved maximum addition/removal in 4 h. The likely presence of iron sulphide in samples drawn from test vessels during both test runs indicates that bacterial sulphate reduction is occurring in this composite.

Sorption of Aluminum by Sulfate-Reducing Bacteria Isolated from Uranium Mine Tailings

Biosorption of aluminum by sulfate-reducing bacteria isolated from uranium mine tailings was examined. A top agar method with Alizarin Red S was used for initial screening of the isolates for aluminum tolerance and biosorption. Five strains of aluminumion-fixing sulfate-reducing bacteria and a strain designated UFZ B 406 isolated from another source were used in the experiments. The mechanism of aluminum biosorption was found to be a passive one. Freezing and thawing of the cells resulted in higher sorption of aluminum, whereas heat treatment or the uncoupler carbonyl-cyanide-m- chlorophenylhydrazone (CCCP) had no effect. The pH value had significant influence on the aluminum ion adsorption, the most absorbance being at pH 3 and 5, and the lowest at pH 7. Addition of magnesium and the presence of iron sulfide precipitates decreased aluminum sorption. The relationship between biomass and Al3+ ions accumulated was linear. Polyphosphate granules as possible site of aluminum accumulation were not found to be present. Fluorescence microscopy showed deposition of aluminum ions exclusively on the surface of the cell. Use of the isolates in bioremediation processes for removing aluminum from water is considered.

Reactivity of Ag+ ion with thiol ligands in the presence of iron sulfide

AbstractDissolved silver (Ag) in the presence of amorphous iron sulfide(FeS) rapidly equilibrates to ultra‐trace levels ( ∼5 ng/L), which agrees with equilibrium calculations based on Ag2S solubility. This finding, along with the authors' discovery that crystalline Ag2S (acanthite) precipitates rapidly under supersaturated conditions, suggests that a discrete Ag‐S phase is formed. Furthermore, potential interferences (Cl−, Cu2+, and dissolved organic carbon) show no effect on the Ag‐FeS system. Only the presence of organosulfur (thiol) ligands at 10−3 to 10−4 M result in increased dissolved silver. Agreement between calculations and measured values were good for 1.8 × 10−4 M 3‐mercaptopropanoic acid; however, calculations predicted higher dissolved silver than measured values for higher thiol levels, possibly due to Ag‐thiol binding to FeS.

Sulfur at Mercury, Elemental at the Poles and Sulfides in the Regolith

We propose that the bright radar spots seen at Mercury's north and south poles are a result of volume scattering from elemental sulfur. Further we suggest that the high average index of refraction for surface materials and notable microwave transparency of the Mercurian regolith can be explained by the presence of iron sulfides (troilite, pyrrhotite) and low-iron sulfides (daubreelite and sphalerite). Sulfides deposited throughout the regolith are a result of fumarolic and magmatic events following initial accretion of meteoroids rich in troilite and pyrrhotite to the planet. Calculations are made illustrating how solar abundances of sulfur volatilized from such a surface can provide an adequate supply over the history of the planet to be cold-trapped at high latitudes, be covered partially with dust, and be seen as bright regions in radar images. To test our hypothesis, we suggest a series of observations in the ultraviolet to search for the SI multiplet centered at 1814 Å, in the midinfrared to search for emissivity features at 7.7 and 11.8 μm, and at millimeter wavelengths to search for sulfureous molecules like H2S and SO2.

Thermodynamic analysis of the thermochemical decomposition of H2S in the presence of iron sulphide

AbstractThe decomposition of H2S by a two‐step closed loop thermochemical decomposition process was investigated. In the first step, H2S decomposes by reacting with iron sulphide to produce hydrogen and a solid solution consisting of FeS and S2. In the second step, the solid solution is decomposed at high temperature to recover sulphur and the iron sulphide which is reused in the first step. The thermodynamics of the first reaction were studied in detail by taking into account 12 gas phase chemical reactions and the phase equilibrium that is established between the sulphur in the gas and in the solid solution. The non‐linear system of 13 equations, which relate the fugacities of the components at equilibrium to the equilibrium constants, were numerically solved by the Newton‐Raphson iteration technique. The calculation results showed that the gas phase at equilibrium contains predominantly H2S, H2, and H2S2. The equilibrium conversion was found to decrease with increasing temperature; however, when the sulphur content of the solid solution was small, high hydrogen yields were possible even at high temperatures.