Papers by Keyword: Sulfur

Abstract: The paper discusses the important issues concerning recycling of industrial sulfur waste and bottom ash. The process flow diagram was designed to form protective coatings on cement concrete by impregnation with molten sulfur, which featured high strength, performance properties and corrosion resistance. The process parameters were specified. The addition of bottom ash slag to cement concrete not only offers a means for recovering waste from thermal power stations, but also increases the material strength. Besides, the impregnation process provides low thermal conductivity for concrete while giving the material high heat insulation. A higher strength of the samples containing bottom ash slag results from a high dispersity and reactive surface of bottom ash slag. The paper investigates the influence of the electrophilic agent (aluminum chloride) on the properties of sulfur binder. It was shown that addition of aluminum chloride encouraged the formation of a more effective protective coating that gave the samples of cement concrete higher strength, density, water resistance. The electrophilic agent stimulated the synthesis process for inorganic sulfides and composite materials based on them. It was found that addition of the electrophilic agent (aluminum chloride) reduced the viscosity of molten sulfur significantly, which was attributed to the formed short-chain sulfur radicals. Such a melt has a relatively high penetration capability to ensure the formation of a high-quality protective coating.

Abstract: The paper investigates the recovery problem of waste sulfur from metallurgical, oil and gas plants. The method was developed to synthesize inorganic sulfides and sulfur concretes from them using the activating agent – titanium chloride and different silica-containing raw materials. The chemical interaction between sulfur, titanium tetrachloride and silicon dioxide encourages the formation of a strong and compact structure in the material. The physical chemical and quantum chemical calculations confirmed the formation of titanium silicate sulfide and made it possible to suggest the concept of sulfur concrete synthesis. It was found how the amorphous component in the filler influenced the properties of sulfur concrete. The physical mechanical tests were performed on the specimens of sulfur concrete, based on opal crystobalite rock from the different fields. The optimum sulfur concrete formulation was determined. The specimens with the optimum composition have high coefficient of resistance to HCl, H₂SO⁴, CaCl₂, NaCl, MgSO₄ solutions, high impact resistance, freeze resistance and density to meet GOST concrete standard. The resulting materials can be used for production of some construction materials: paving slabs and blocks, road building materials.

Abstract: This paper is describing an investigation of surfactants influence on zinc sulfide wetting by non-polar liquids and sphalerite concentrates pressure leaching parameters. Zinc sulfide preferential wettability by oil was tested in presence anionic surfactants with different chemical structures. Interfacial tension was determinated by the maximum liquid drop volume method. It allows to determine surfactant potential effectivity on pressure leaching of sphalerite concentrate. It is found that SDBS decreases zinc sulfide wettability by non-polar liquids in a greater degree than SDS and Ls. Combined addition of Ls and SDBS allowed to receive residues with optimal coarseness, eliminate pellet formation and increase zinc extraction.

Abstract: The aim of this work is to use a residue from shale gas production, known as retorted shale (RS), as an alternative material for processes of sulfur adsorptive desulfurization in liquid fuels such as gasoline or diesel. Therefore, retorted shale samples were chemically modified. Two methods were applied: acid leaching and impregnation. The first method (RS-HCl) was an acid treatment with HCl solution (3M) in proportion of 1.5: 10. The second method (RS-Fe) was a wet impregnation of 20%wt. of Fe followed by calcination at 700°C for 2 h. The adsorbents were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The adsorption tests were performed using a solution of n-heptane and thiophene to simulate a fuel with an initial concentration of 500 ppm of sulfur. The results showed that both methods significantly altered the structure of the retorted shale, mainly the amount of Fe₂O₃. The adsorption test results indicated that the adsorbents prepared can remove up to 90% of the sulfur present.

Abstract: Slag bases for welding materials have been developed from mineral raw materials and man–made mineral formations of the Urals. Successful comprehensive studies and tests of fused fluxes and also of weld metal and weld joints obtained by these welding materials have been carried out. It has been clearly established that the obtained weld metal has low content of harmful impurities ([S] is as low as 0.01 wt%) due to the use of the electric arc furnace method, purity of the feedstock minerals and technogenic raw materials and physicochemical reactions during the welding process.

Abstract: In this article, the electrochemical properties of elemental sulfur dissolved in alkaline solution has been studied for the first time using the method of removing the anodic and anodic-cathodic potentiodynamic polarization curves on rhodium electrodes. The influences of different parameters for oxidation process of elemental sulfur, namely sulfur component in electrolyte concentration, scan rate and temperature were investigated. The resulting polarogram presented in oxidation reaction of polysulfide ions to elemental sulfur process. This shows that polysulfide-ions in electrolyte at cathodic polarization was restored to monosulfide, and monosulfide –ions oxidized to elemental sulfur. The effective activation energy was calculated which equals 13,67 Kj/mol, indicating the oxidation reaction of sulfur occurred in diffusion mode.

Abstract: The vessel containing sulfur particles has been found failing due to the effect of corrosion and erosion by the sulfur particles. Several coatings, including zinc-aluminum coating, wear-resistance painting and two kinds of polymer, have been provided to resist the negative influence of sulfur in the present study. The wear and corrosion resistance of the selected coatings has been measured to study the performance difference. Impact test has also been done to investigate the bonding condition of coatings under the impact or bending load. The microstructure of coatings before and after wear test is observed by the Optical Microscope (OM) and Scanning Electron Microscope (SEM). The experiment results reveal that one of the polymer coatings shows the best performance in the corrosion resistance, another polymer coating’s wear resistance is better than others. The coatings are bonded well with the substrate except the zinc-aluminum coating. The performance of painting is ordinary in this investigation.

Abstract: The chemical composition and particle size distribution as well as the physical-mechanical characteristics of fly ash of Krasnokamensk combined heat and power plant (CHPP) were determined. The revealed features provided the development of the technology of fly ash enrichment. The composite building material based on both fly ash of Krasnokamensk CHPP and technical sulfur was developed. Aluminum chloride was proposed to be used as modifier. The basic physical-mechanical properties of sulfur crushed stone were investigated.

Abstract: Tristrimethylsilylgermane, (Me₃Si)₃GeH, was employed as a molecular model compound for hydrogen terminated Ge(111) surfaces. Time and temperature dependent NMR spectroscopy yielded rate constants for the reaction between (Me₃Si)₃GeH and elemental sulfur and allowed for the determination of the activation energy for this molecular model reaction to mimic germanium surface passivation.

Abstract: Problems of transforming heavy crude high-sulfur oil into low-sulfur fuels and oils become increasingly urgent for oil refineries. The main reason for that is depletion of low-sulfur oil-fields and following rise of heavy crude oil share in world's oil production. Desulfurization of oil and petroleum residues is performed by breaking down or extraction of sulfur and sulfur compounds with catalyst and chemical additives which leads to considerable rise in price of refinery. Desulfurization technology proposed in the following research involves simultaneous use of the acoustic and hydrodynamical cavitation for breaking down long molecular connections. Oil refinery was performed in the electromechanical vortex layer activator which intensified mechanoactivation processes by intensive movement of ferromagnetic elements in the external magnetic field.