Papers by Keyword: Sulfur

Abstract: A study was conducted to investigate the effect of activator types KOH, ZnCl₂, and H₃PO₄ on the specific surface area of porous carbon and its performance as a Li-S battery. Porous carbon was synthesized from candlenut shells through a carbonization process at 700 °C using three types of activator solutions with a concentration of 0.36 M. The porous carbon activated with KOH achieved the best results, with a specific surface area of 681 m²g^-1. The porous carbon candlenut shell-sulfur (PCCS-S) composite was obtained by the solid-state reaction method in a ratio of 1:2.5 w% and heat-treated at 155 °C to form the PCCS-S composite. The PCCS-S composite was then made into a slurry and coated onto Al-foil to obtain a layer of electrodes with a thickness of 200 µm. The PCCS-S cathode was then assembled into a coin battery with lithium metal as the anode and an electrolyte of 1.0 M LiTFSi solution dissolved in 1,3-dioxolane (DOL) and 1,2-dimethoxyethane (DME) (v/v, 1:1). Charge-discharge characterization was carried out at a charge rate of 1 C for 50 cycles. Characterization shows that the performance of the PCCS-S KOH composite cathode Li-S battery is stable at a specific capacity of 324 mAhg^-1 after the first 10 cycles, with an average Coulombic efficiency of around 86.8 %.

Abstract: Hydrodesulfurization (HDS) technique is no longer applicable in achieving ultra-low sulfur diesel because of high operational cost, high operating temperature and low efficiency. Due to these disadvantage, catalytic oxidative desulfurization (Cat-ODS) has been introduced as a new technique in achieving ultra-low sulfur diesel. The performance of the Fe catalyst was investigated in Cat-ODS of model diesel using terbutyl hydroperoxide (TBHP) as oxidant and dimethylformamide (DMF) as an extracting solvent. The physicochemical analysis of this catalyst was accomplished using several characterization techniques such as BET, EDX and HRTEM. It posseses high surface area of 226 m²g^-1 with small particle sizes in the range of 6-7 nm and less metal leaching. Under optimize condition, about 90% of sulfur was removed from model diesel. In the absence of catalyst, only about less than 80% of organosulfur compounds were removed. The Cat-ODS system showed the promising technology to be compliment with hydrodesulfurization (HDS) to produce low sulfur diesel.

Abstract: This work presents the results of optimization compositions of polymer-modified binder (PMB) by a compromise task. The conducted study of influence two prescription factors – containing styrene-butadiene-styrene and sulfur – on which is a set of indicators of polymer-bitumen binders were carried out. The regularities of these factors of mutual influence were established by such indicators as the Fraas brittleness temperature, penetration, softening point, ductility. The dosages of SBS and sulfur have been determined by ensuring the achievement of the required level of PBB indicators in accordance with GOST R 52056-2003 «Bitumen-polymer road binders are based on styrene-butadiene-styrene block copolymers. Specifications».

Abstract: Analysis of literature sources, as well as practical data indicate that the existing scientific, technical and technological developments to ensure reliable corrosion-mechanical resistance and durability of oil and gas pipelines and other shell metal structures of critical use and subordinate to the State Service for Mining Supervision and Industrial Safety of Ukraine largely find contradictions and uncertainty; there are no quantitatively substantiated recommendations for practical application in order to ensure corrosion and mechanical resistance of pipelines operating in technologically aggressive environments under alternating temperature and barometric conditions and loads; there is a need for a systematic study of the causes, conditions and mechanisms of corrosion and mechanical damage of long-term equipment, which will significantly increase the operational reliability of industrial equipment. Experimental studies have established the causes and substantiated the mechanisms of metal softening with increasing service life (from 0 to 25 years) that leads to its degradation, especially during long-term operation in corrosive environments. A method for forecasting the residual working (accident-free) life of pipeline metal structures has been developed, which makes it possible to purposefully regulate their operational condition. This allows the timely use of technical, design and technological measures to improve the performance of such structures. Numerous and diverse results of experimental tests of metal samples for various purposes have been obtained, which provide an opportunity to create a base for comparative analysis of steels in many parameters of crack resistance, which will become a reliable basis for scientific and practical substantiation of the equivalent replacement of some steel grades with other grades, taking into account technological loads, corrosive environments and others.

Abstract: Based on the reason that SBS modified bitumen (SMB) with sulfur stabilizer is easy to degrade during aging, a novel non-sulfur stabilizer, P-benzoquinone oxime (GMF), was used to modify SMB. The effects of GMF and sulfur stabilizer on the thermal storage stability, low-temperature performance and aging resistance of SMB were investigated. The results indicate that GMF is more beneficial to improve the thermal storage stability, the low temperature flexibility and softening point of SMB than that of sulfur. And GMF can restrain the degradation of the low temperature flexibility of SMB after thermal aging as compared with sulfur. Fourier transform infrared spectroscopy indicates that the aging growth index of GMF/SBS modified bitumen is 33.5% lower than that of sulfur/SBS modified bitumen after aging. Fluorescence microscope proves that the addition of GMF can prevent the destruction of cross-linking network structure of SBS in bitumen during aging process, which also demonstrates that GMF can improve the aging resistance of SMB. Therefore, GMF can be more suitable as a stabilizer for SMB.

Abstract: This work presents studies on the material composition and physico-mechanical characteristics of an alumina-containing estimate formed during the production of aluminum on electrolyzers with self-baking anodes during technological operations. The material is a mixture of fine powder 2.5 mm in size (62.78% on average mass) with the presence of pieces of material ranging in size from 0.5 to 6 cm (average 20.26% by weight). The samples contain pieces of hardened aluminum with sizes from 5 to 20 mm (16.96%). The largest content in the sample has the fineness classes-0.315 + 0.16 mm in the volume of 29.85% and the largest class +2.5 mm-37.22%. B It was established that aluminum is concentrated in the fractions-0.315 + 0.16 mm (45.7%) and 0.16 + 0 mm (48.8%), silicon in the fraction-0.63 + 0.315 mm (1.91%), iron at-1.25 + 0.63 mm (0.601%) and-0.63 + 0.315 mm (0.62%). The material consists of cryolite (Na₃AlF₆), chiolite (Al₃F₁₄Na₅), quartz, feldspar, carbonaceous matter and the technogenic phase of the composition (NaF) 1.5CaF₂ AlF₃. The material is characterized as non-abrasive (working index Ai - 0.0184) and very soft in relation to impact crushing (working index CWi - 3.64), the working index of ball grinding Bond (BWi - 6.47) characterizes a very low resistance to ball grinding. The implementation of the crushing operation of an alumina-containing estimate will allow the use of dry cascade-gravity and centrifugal classification to separate impurities in the form of SiO_2, and Fe₂O₃ for the use of alumina-containing material in primary aluminum technology. On the basis of laboratory tests, it is established that alumina-containing raw materials can be separated and photometric and gravitational separation methods can be used. A mathematical model of the motion of particles of primary and prepared alumina-containing raw materials in a cascade-gravity classifier was developed. The criteria and factors characterizing the alumina-containing material, as well as influencing and determining the maximum material enrichment, are established.

Abstract: The paper presents the results of the effect of boron, manganese and sulfur on the microstructure and mechanical properties of pipe steel 17G1SU. It was shown that the microstructure of boron-free steel sample containing 1.4% Mn and 0.01% S consists mainly of ferrite and a small amount of perlite. Samples microalloyed by boron are represented by a dispersed ferritic-bainitic structure. A decrease in ferrite grain size from 8.7 μm, in a comparative sample without boron containing 1.4% Mn and 0.010% S to 5.8 μm in a sample of steel containing 0.006% B, 1.6% Mn and 0.011% S, shows increasing the dispersity of the ferritic-bainitic structure. A decrease in the manganese content to 1.4, sulfur to 0.004% and an increase in boron concentration to 0.0011%, despite an increase in grain size to 6.8 μm, retain a fine-grained structure. The effect of boron, manganese, and sulfur content on the microhardness of the structural phases of the studied pipe steel samples is noted. The smallest microhardness of ferrite and perlite is observed in the base sample without boron, reaching 180 and 214 HV10, respectively. The microalloying of pipe steel containing 1.6% Mn, 0.011% S with boron is accompanied by an increase in the microhardness of the bainitic phase to 314 HV10, which increases to 400 HV10 with an increase in boron concentration to 0.011%, and a decrease in the content of manganese and sulfur to 1.4 and 0.003%. In this case, the microhardness of the ferrite phase, reaching an increase to 260 HV10, is practically independent of the content of boron, manganese, and sulfur. The mechanical properties of the experimental metal rolling with a thickness of 10 mm provide the production of rolled steel of strength class X80, without heat treatment, regardless of the content of boron, manganese, and sulfur, as a result of the formation of a finely dispersed ferrite-bainitic structure.

Abstract: Increasing demands on the quality of graphite cause carrying out detailed studies of its desulfurization. Combined sulfur present in natural graphite reduces the heat transfer coefficient, increases the heat energy consumption, pollutes the atmosphere with harmful emissions in the process of their application in various branches of industry. The technology and deepness of desulfurization is determined by the total content and ratio of various sulfur compounds in graphite. Previously, a number of technologies for cryptocrystalline graphite enrichment had been developed by the authors. However, the use of these technologies does not effectively reduce the sulfur content in the graphite composition. Therefore, the aim of this work is to develop activation methods that can reduce effectively the sulfur content in the composition of cryptocrystalline graphite. In order to reduce the total sulfur content, mechanical and electro-explosive-pulsing activation were tested. Mechanical activation of graphite was carried out in АGО-2, DCM, D-100 activator mills in different environments and at different activation time. To implement electric-explosive-pulsing activation, special equipment was used. In the process of the research it has been found that the use of mechanical activation and electric-explosive-pulsing activation does not reduce the sulfur content below 0.25 wt.%. Mechanical activation of graphite in different modes enables more intensive release of sulfide minerals from aggregate graphite formations and their intensive oxidation.

Abstract: The study solved the problem of determining the technological mode of operation of the device for loading solid lumpy and granulated sulfur into a melting bath with molten liquid sulfur. For this it is necessary to solve two main problems: to determine the method of loading solid sulfur into the melt, to calculate the main design and technological parameters to ensure the required performance of the smelting bath. As a result of experimental studies, the mode of operation of the loading device was obtained, during which the partial melting of the surface of sulfur particles in the surface layer of the melt occurred. This led to the adhesion of particles to each other, the formation of conglomerates having a size that is much larger compared with that of particles of the initial particle size distribution. As a result of this phenomenon, the melting rate and the melting bath were significantly reduced, filled with a solid phase. As a result of the study, a model was developed and the problem of calculating the limiting modes of the loading device operation was solved for preventing solid particles from sticking together.

Abstract: Theoretical and experimental studies including a study of slag viscosity of the CaO-SiO₂-B₂O₃ system containing 25% Al₂O₃ and 8% MgO and equilibrium interphase distribution of sulfur and boron between slag and a low-carbon metal were carried out using a simplex-lattice experiment design and HSC 6.1 Chemistry software (Outokumpu). Fundamental research has contributed to the development of technology of basic boron-containing slags formation in ladle at ladle-furnace. These slags have a low viscosity, retaining high refining properties and providing direct microalloying of steel by boron. This technology has no analogues in domestic and foreign practice. The development of technology in the converter plant AO "ArcelorMittal Temirtau" (Kazakhstan) provided low-carbon steel production in wide grade composition, containing 0.001-0.008% boron and 0.004-0.014% sulfur, decreased consumption of manganese, high mechanical properties of rolled metal and improved environmental conditions.