Low Sulfur Content Research Articles

Mesoporous Ag2O/ZrO2 heterostructures as efficient photocatalyst for acceleration photocatalytic oxidative desulfurization of thiophene

The production of fuels with a low sulfur content has been paid significant attention in the manufacturing of petroleum refining due to the progressively severe environmental legislations obliged by governments worldwide. In this paper, for the first time, two dimensional mesoporous Ag2O/ZrO2 heterostructures were synthesized by a facile approach for thiophene photocatalytic oxidative desulfurization under visible-light exposure at room temperature. The Ag2O/ZrO2 heterostructures significantly enhanced the photocatalytic desulfurization of thiophene obeyed the pseudo-first-order model compared to pristine ZrO2 NPs. In particular, 1.5%Ag2O/ZrO2 photocatalyst exhibited better photocatalytic performance and the correspondent rate constant of 0.0235 min−1, which was promoted 5.35 times than that of pristine ZrO2 NPs (0.0044 min−1). The desulfurization rate of thiophene over 1.5% Ag2O/ZrO2 heterostructure was enhanced 3.7 times larger than that of pristine ZrO2 NPs. The thiophene was photocatalytically oxidized to CO2 and SO3. The photocatalytic performance of Ag2O/ZrO2 could be enhanced because of its synergetic effects, the intense visible-light harvest, rapid mobility of the thiophene to the active sites, a lower light scattering effect, and a large •OH radical contents formed. Moreover, the Ag2O/ZrO2 heterostructures revealed excellent stability toward the photocatalytic oxidative desulfurization of thiophene. A possible charge separation mechanism over mesoporous Ag2O/ZrO2 heterostructures was proposed.

Geochemical characteristics and, origin of heavy oil in the periphery of Wenchang-B depression in Zhu III Sub-basin, Pearl River Mouth Basin, China

Heavy oil reservoirs have been discovered in the periphery of Wenchang-B depression in Zhu III sub-basin, but there is no relevant research on the geochemical characteristics and genesis of heavy oil. The characteristics of source rocks and crude oil were analyzed by various geochemical experiments. The results indicated that: (1) Second member of the Wenchang Formation (WC2) source rock has the largest hydrocarbon generation potential, WC1 and EP source rocks have similar characteristics, but EP source rocks have low maturity and Pr/nC17 greater than one; (2) Its heavy oil-density ranges from 0.91–0.97 g/cm3, with low sulfur content. The saturated hydrocarbon content in well Q4 is high, whereas it has low the non-hydrocarbon content. The carbon isotope values range from −28.2 ‰ and −25.4 ‰. Combined with the biomarker characteristics, the source of heave oil corresponds to WC2 and WC1 source rocks. Hence, there are two origins of heavy oil in the Wenchang-B depression, low-mature heavy crude oil (well Q4), and biodegradable heavy oil (well Q1). Clarifying the origin and source of heavy oil can provide more references for exploration and development.

Measurements of Liquid AISI 304L Steel Density and Surface Tension, and Influence of Surface‐Active Elements at High Temperatures

Within the framework of the welding of steel components in pressurized water reactors, the optimization of the weld pool penetration is a major issue. The thermal‐hydraulics of the molten steel pool can be driven by Marangoni flows at the free surface. To compute these flows, liquid steel's thermophysical properties such as density ρ and surface tension σ are required. Such properties for austenitic vessel steel AISI 304L at liquid state are scarce, and even not available above 1800 °C, due to technological issues. The viscometer temperature installation (VITI) is designed to implement sessile droplet (SD) and maximum bubble pressure (MBP) techniques. These techniques allow to determine original ρ and σ data for two grades of AISI 304L steel, namely 304LP1 and 304LP4—low and high sulfur content, at various temperatures. In particular, thanks to the innovative design of MBP configuration, original surface tension data are obtained from the melting point up to 2100 °C. For the first time, experimental evidence of the Sahoo et al.'s (1988) model at high temperature is provided, emphasizing the decisive role played by surface‐active elements such as sulfur and oxygen on surface tension, whose content evolution is assessed by dedicated chemical analyses.

Significant enrichment of Rb and Cs in the Late Triassic coals from the Coc Sau surface mine, Cam Pha Coalfield, Quang Ninh Province, Vietnam

The current study investigates the mineralogical and geochemicalcharacteristics of the Late Triassic coals from the Coc Sau open-pit mine, Cam Pha Coalfield (Quang Ninh Province, Northeastern Vietnam) using Powder X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), inductively coupled plasma atomic-emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). Coals from Coc Sau open-pit mine are characterized by medium ash yield (avg. 29.7%), low sulfur content (avg. 0.17%), and low moisture content (avg. 1.8%). The volatile matter content (avg. 8.4%) indicates a semianthracite rank. The crystalline phases identified in Coc Sau coals and host rocks (roof, floor, parting) are primarily quartz, kaolinite and muscovite, with small proportions of ankerite, clinochlore, anatase, calcite, and tobelite. Illite, pyrite, and siderite were occasionally detected in individual samples. In addition, several minerals below the XRD detection limit, such as barite, apatite, zircon, xenotime, and florencite were observed by SEM. The low sulfur concentrations, low Sr/Ba ratio and relatively high ash yield of these coals indicate a continental lake basin sedimentary environment with a relatively strong supply of terrigenous detritus. Quartz, kaolinite, and muscovite were most likely derived from the terrigenous source region surrounding the basin, and the other minerals are mainly of authigenic origin. Relative to worldwide coals, the Coc Sau coals and host rocks are highly enriched in Rb and Cs, which can be a potential source for Rb and Cs recovery during coal utilization and combustion. Rubidium and Cs enriched in the coals are positively correlated with Al and K, indicating that they most likely occur in potassium-rich clay minerals (e.g., muscovite), and originate from weathered felsic terrigenous detritus.

High-sulfur bitumen amplifies the effect of polyphosphoric acid

This study examines the effect of polyphosphoric acid (PPA) in bitumens with low-sulfur content and high-sulfur (10% sulfur) content. The recently lowered limit on the sulfur content of marine fuel will result in increased sulfur content of the bitumen remaining at the bottom of the barrel. Since the effect of PPA on bitumen's performance highly depends on bitumen’s composition, we hypothesize that high-sulfur bitumen, with an increased content of sulfoxide due to aging, will have higher intermolecular interactions with PPA leading to increase in bitumen’s elasticity. We used computational modeling and laboratory experiments to examine this hypothesis. Based on the results, under laboratory aging, the content of sulfoxide is increased for bitumen samples containing sulfur; a greater increase is observed for high-sulfur bitumen. Our molecular modeling, showed that H-bonding and H-transfer interactions of PPA’s terminal OH with sulfoxide’s polar group (S = O) are responsible for the effective interaction between the two components. The H-transfer interaction has a considerable binding energy (-70.0 kcal/mol), although it is not dominant. H-bonding interactions, with lower binding energy (−(17–22) kcal/mol), are dominant. The high concentration of sulfoxides and dominant contribution of H-bonding interactions can provide an impressive improvement in bitumen’s performance. Upon the introduction of PPA to each bitumen, high–sulfur bitumen showed about 22% increase in percent recovery, while low-sulfur bitumen showed about 12% increase in percent recovery. A higher percent recovery is an indicator of enhanced elasticity. This was also evidenced in a significantly higher complex shear modulus in high-sulfur bitumen compared to low-sulfur bitumen.

Multifunctional, environmental coatings on AA2024 by combining anodization with sol-gel process

The present work proposes the development of multifunctional composite coatings on AA 2024 by combining anodization and sol-gel process. To render the surface of AA 2024 with maximum corrosion resistance, eco-friendly citric-sulfuric acid (CSA) electrolyte with low sulphur content was used for anodization at 20 V for a duration of 30 min. The obtained anodized layer was porous. Ambient curable hybrid sol-gel coating with 8-hydroxy quinoline (8-HQ) as corrosion inhibitor was used as a sealant for the porous anodized layer to enhance the corrosion resistance with self-healing properties. Surface pre-treatments were carried out using sand blasting and alkaline etching to ensure high surface activity prior to anodization. The surface morphology and chemical composition of samples with and without coatings were characterized by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopic analysis (EDX). Adhesion strength and wettability of the coatings were measured by tape adhesion test and water contact angle analysis respectively, which revealed excellent binding strength and hydrophobic nature. The corrosion resistance of the coatings was evaluated using electrochemical impedance spectroscopic (EIS), potentiodynamic polarization and salt spray tests. The results revealed improved corrosion resistance of anodized + 8-HQ sealed AA2024. Moreover, when the coated samples were scribed and exposed to the corrosive medium, the SEM/EDX mapping confirmed presence of corrosion inhibitors at the location of the defect, thereby confirming the self-healing property. Hence, the proposed system is a chromium-free, environment friendly multifunctional system exhibiting excellent self-healing corrosion protection and can be a promising substitute for chromic acid anodization.

Морське паливо з низьким вмістом сірки, перспективи виробництва в Україні.

The article considers the main global trends in the use of fuel for shipping. The necessity of replacing marine fuel oils of the F-5 and F-12 grades, which are currently widely used by the merchant fleet of Ukraine, with new fuels with a low sulfur content, such as marine gas oil (MGO) or low sulfur marine gas oil (LS-MGO), is substantiated. The main problems are characterized, and in turn, they may arise during the transition of shipping to new types of fuel taking into account the role of cargo transportation by sea. Directions for solving these problems without a significant impact on the cost of cargo transportation are proposed, consisting of the selection of raw materials, their preliminary processing, the use of the latest processing technologies and compounding of finished commercial products. The selection of raw materials consists of determining the types and grades of raw materials that are provided with sufficient industrial reserves for the implementation of the selected technology and are characterized by a certain level of quality, for example, low (<0.5 %) sulfur content. The use of the latest technologies consists of thermal (cracking, pyrolysis) and thermocatalytic (catalytic cracking and pyrolysis, hydrotreating and hydrocracking) processes for obtaining fuel with a low sulfur content from hydrocarbon raw materials. Fuel compounding occurs with components with a significantly lower sulfur content. For this, various petroleum distillates, commercial fuels, some liquid products of coal gasification, as well as products of thermal degradation of polymer raw materials can be used. In practice, in the production of marine fuel with a low sulfur content, the most effective combination of several directions in a single technological chain: "selection of raw materials - the latest technologies" or "selection of raw materials - the latest technologies - compounding". Considering the above, it is shown that at present one of the most promising technological processes for the production of motor fuels, in particular marine ones, in Ukraine catalytic pyrolysis of secondary polymer raw materials on zeolites can be considered. Key words: marine fuel, sulfur, shipping, environmental requirements, polymers, pyrolysis, catalyst, petroleum distillates, coal gasification products. Corresponding author: A.B. Grigorov, e-mail: grigorovandrey@ukr.net

Transcriptome Analysis of Soybean in Response to Different Sulfur Concentrations

Sulfur is an indispensable nutrient for plant growth and development, and is important in the synthesis of sulfur-containing amino acids. Although several studies on the effects of some macronutrients, including nitrogen and phosphorus, have been conducted on the performance of several crops at the genomic level, studies on the effect of sulfur on crop performance are limited. Therefore, this study aimed to examine the effect of different sulfur concentration on the transcriptome of soybean. Additionally, soybean yield parameters were also examined. Two soybean varieties, DND252 and HN84, were exposed to low and high concentrations of sulfur, and differentially expressed genes (DEGs) were identified using transcriptome analysis. The study results showed that the DEGs identified in the DND252 variety were involved in stimuli response, DNA binding and cell periphery under low sulfur concentrations. Also, the DEGs identified under high sulfur concentration were involved in membrane and membrane parts. Additionally, DEGs identified in the HN84 variety under low sulfur concentrations had similar functions as those identified in DND252 under high sulfur concentrations, indicating that HN84 was more sensitive to sulfur concentration changes than DND252. However, under higher sulfur concentrations, the DEGs identified in HN84 were primarily involved in membrane and membrane parts, indicating that high sulfur can cause cell membrane damage. Furthermore, soybean grown using 2.0 mmol/L sulfur had the best yield. The findings of this study identified candidate genes for the breeding and development of sulfur-efficient soybean varieties.

Обзор отечественных разработок в области противоизносных присадок для дизельных топлив с низким содержанием серы

The analysis of the production volumes of diesel fuel with a low sulfur content in Russia is carried out. The need of diesel fuel manufacturers for anti-wear additives has been determined, taking into account the forecast of the Ministry of Economic Development until 2030. The domestic patents for anti-wear additives for diesel fuel are considered in detail and the best indicators of lubricity for each invention are given. The analysis of the dynamics of registration of domestic inventions on the method of obtaining anti-wear additives for the period from 2005 to 2020 is carried out. The article also shows the dependence of the lubricating ability of diesel fuels on the concentration of an anti-wear additive in the fuel and its composition. This review can be used by scientific and project groups when formulating a research hypothesis or for conducting a patent search. The article will be useful when preparing an application for intellectual property protection in this direction. In addition, the results of the review can be used in the formation of a feasibility study of an investment project and in the study of the domestic market of anti-wear additives for diesel fuel hydrotreating.

In-Situ upgrading technology: Nanocatalyst concentration levels effects and hydrocarbons paths in the porous medium

The current research work contributes one further step in developing the heavy oil in-situ upgrading technique. The experimental work was carried out using a dolomite corepack as a porous medium at temperature and pressure already investigated in In Situ Upgrading Technology (ISUT). Crude oil was saturated in the corepack to simulate the oil in place in the reservoir; then, hot vacuum residue (VR) plus nanocatalyst, and in the presence of hydrogen (H2) was continuously injected into the porous medium. The nanocatalyst was composed of ultradispersed Ni–Mo and deposited in three incremental steps in the corepack. Depositing catalyst in the corepack aimed to create a reactor in which upgrading reactions can occur. After each incremental nanocatalyst deposition step, the hot VR and H2 continuously flowed at a selected temperature, pressure and residence time through the corepack. The products of every VR plus H2 step were analyzed with techniques such as microcarbon (MCR), simulated distillation (SimDist). The products from the stage with the highest catalyst concentration were determined to have lower VR contents, much lower viscosities, lower sulfur content, and stability; this latter indicating the necessity of carefully controlling processing severity levels. Chemical tracers were added to the crude oil (Phenanthrene) and the VR (1-methylnaphthalene and n-octadecane) at a 1.0 wt% level; their distributions were studied throughout the process via chromatography and mass spectrometry analyses. Cracking, plus olefin and aromatic hydrogenation reactions were evidenced to occur during the ISUT process.

“GREEN” POLICY AND ENVIRONMENTAL TAXATION AS THE INSTRUMENTS TO TACKLE CLIMATE CHANGE

The article is dedicated to environmental taxation as one of the possible policy instruments that along with other governmental and partnership measures could tackle climate change and assure green growth for the world and Ukraine in particular. European countries mostly focus on the taxation of energy sources, which allows them to be highly efficient in the field of GHG taxation. The Ukrainian model insists on controlling the level of environmental pollution for many years, it has low efficiency and control potential, high transaction, and administration costs. Price instruments for limiting greenhouse gas emissions are one of the most effective and rational solutions during the exacerbation of the climate change issue. These include taxes (on CO2 emissions that are directly related to emissions or the carbon content of fuel and excise duties on energy carriers) along with emissions trading systems. With the establishment of excise duty on energy and carbon taxes, states form a price for each ton of CO2 emissions, which contributes to dynamic efficiency, by stimulating technological changes to the development of innovative emission reduction technologies and static efficiency, i.e., reduction of CO2 emissions in the most financially affordable way. Excise duty on energy resources and taxes on CO2 emissions have the similar object of taxation, although the rates of excise taxes in the vast majority do not depend on the carbon content of the fuel. They are differentiated in the direction of promoting the competitiveness of more ecological types of fuel (reducing the rate for fuel with a lower sulfur content), protecting producers of energy-efficient enterprises, and preventing energy poverty. The excise duty rate consists of Pigou and Ramsay components, the proportions of which are chosen by fiscal necessity and occupy a large share of budget revenues. They are harmonized between EU countries with a unified approach. In common practice, funds accumulated from carbon tax should cover the damages caused to society and the costs of protecting and restoring an environment. Therefore, the article identifies the key groups of environmental taxes in the EU countries, analyses the European experience of the economic impact on environment preservation, examines possible ways of environmental taxation reform in Ukraine, based on the best foreign experience, and analyses the CO2 emissions among countries and continents by sectors and type of fuel. In addition, the author developed the draft concept of Ukraine's transition to a climate-neutral economy, highlighting the models of side-x-side functioning of the tradable permits system and taxes on CO2 emissions.

Литогеохимические характеристики высокосернистых лечебных грязей оз. Нуху-Нур (Иркутская область): сопоставление с лечебными грязями мира

IIn therapeutic mud (peloids) of Lake Nuhu Nur, major oxides, trace elements, and mineral phases are determined from sedimentary columns taken in the central and near-coastal parts of the lake. In the center of the lake, layers with high and low contents of total sulfur (Stot) and S2− alternate. Sulfur is part of sulfates: gypsum, tenardite, and hexahydrite. The distribution of S is generally correlated with Na2O, CaO, Sr, and U with a strong negative correlation with other major oxides and trace elements. In near-coastal parts of the lake, there are layers enriched and depleted with CaO, which strongly correlates with Sr. Lithogeochemical signatures of peloids show concentration of therapeutic components in the bottom sediments of the lake due to processes similar to weathering of rocks of silicic composition in arid climate. In terms of major oxides and trace elements, peloids from Lake Nuhu Nur are generally comparable to those from Wudalianchi (Northeast China), coastal regions of Brazil, as well as Georgia and Spain, but are closest to therapeutic high-sulfur sulfate mud of Kopahue in Argentina.

Emissões de gases de um motor agrícola de ignição por compressão utilizando misturas de óleo Diesel, biodiesel e etanol

ABSTRACT: Partial fuel replacement strategies arising from fossil sources used in compression ignition engines involve mixtures of mineral Diesel oil, biodiesel and ethanol to minimize the gas emissions. In this study, experimental assessments were performed on a multi-cylinder, turbocharged aftercooler, compression-ignition, agricultural tractor engine provided with electronic injection management and an exhaust gas recirculation (EGR) gas treatment system. Diesel oil containing low (BS10 -10 ppm) and high sulfur concentrations (BS500 - 500 ppm) was utilized, with 10% of biodiesel as a constituent established by Brazilian legislation, in blends with 5, 10, 15 and 20% of the total volume, made up of anhydrous ethanol with additives. Thus, there were eight fuels blends and two reference conditions (without ethanol). The emissions of CO, HC, NOx and the HC+NOx gases were estimated, corresponding to the eight operating modes (M) of the ABNT NBR ISO 8178-4 standard. From the findings, it was evident that with the rise in the ethanol concentrations in the fuel blends there was a corresponding increasing in the CO, NOx and HC+NOx emissions. The HC, on the contrary, exhibited a pattern of higher emissions for the high-sulfur fuels (BS500) at low loads. No difference was observed for the NOx emissions at high loads. In the other operation modes, different behaviors were expressed for the BS10, which sometimes showed an increase, while at other times a reduction in the NOx emissions. Regarding the BS500, the NOx emission increased when the ethanol concentrations rose. As the specific emissions of the NOx were higher than those of the HC (in g.kW-1.h-1), the behavior exhibited by the HC+NOx showed similarity to that of the NOx. When the directly analysis of the operating modes was taken into consideration, the use of ethanol triggered an upswing in the emissions, exceeding the threshold of MAR-1 and EURO V standards.

Valuable metals recovery and vitrification of chromium-containing electroplating sludge

In this work, a two-stage process was developed to recover the valuable elements from chromium-containing electroplating sludge (CES). The low sulfur/carbon Fe-Si-Cr alloy containing 31.61%Fe, 31.78%Cr, 36.59%Si, 0.01%C and 0.01%S was produced, and the recovery extent of Cr reached 98.62%. The CES was pre-desulfurized at 1000–1200 ℃, and reaction between components CaSO4 and Fe2O3 in the CES to produce CaFe4O7 was the main desulfurization mechanism. The desulfurized CES was then reduced by silicon at 1600 ℃ to prepare the Fe-Si-Cr alloy, and the SiO2 generated from the silicothermic reduction helps the vitrification of the slag. The presence of silicon in alloys and the CaO in the slag are the key factors for the low content of sulfur in alloy. Adding CaO also helped to decrease the viscosity of slag, and thus reduced the metal loss by enhancing the slag-metal separation efficiency.

Does the high sulfur content in apricots affect oxidative stress?

Apricots are one of the most important fruits that can be produced worldwide. Most of the importer countries are sensitive about sulfur which is used in the protection of dried apricots. The objective of this study was to compare the effects of feeding with high and low sulfur content apricots on oxidative stress parameters of the liver. In total, 42 Wistar albino rats were fed for 12 weeks with the use of dried apricots containing different amounts of sulfur and sun-dried apricots. There was no significant difference in IL-1β, 8-OHdG and TOS levels between the control group and the group fed with sun dried apricots. There was no statistically significant difference between the groups fed with low and high sulfur-containing apricots.Non-necrotic changes were observed in 3000 ppm and 4000ppm groups in microscopic examination. No significant effect of feeding with sulfur treated apricots was found in the liver tissues of rats.

Sulfurized Carbon Composite with Unprecedentedly High Tap Density for Sodium Storage

AbstractA novel sulfurized carbon decorated by terephthalic acid (TPA) and polyacrylonitrile (PAN), with unprecedently high tap density (≈1.02 g cm−3), is investigated. Room‐temperature sodium–sulfur batteries offer high energy density; however, the dissolution of the polysulfide is a major factor hindering their commercialization. This dissolution problem can be tolerated by inhibiting the formation of polysulfide through binding sulfur to the carbon structure of PAN. Low sulfur content and low volumetric energy density in the composite are other drawbacks to be resolved. Heat‐treated TPA induces a high‐density carbonaceous material with high conductivity. This TPA is partly replaced by PAN, and the produced carbon and sulfur are composited with dehydrated polyacrylonitrile (CS–DPAN), which exhibits higher conductivity and surface area than the sulfurized dehydrated polyacrylonitrile (S–DPAN). The CS–DPAN composite electrode exhibits excellent electrochemical performance, and the resulting volumetric capacity is also superior to that of the S–DPAN material electrode. Operando Raman and operando X‐ray diffraction analyses confirm that the increased capacity is realized via the avoidance of parasitic C60Na3 formation formed below 1 V, by adjusting the operation voltage range. This finding demonstrates the feasibility of carbon–sulfur composites as a high‐energy electrode material for rechargeable sodium batteries.

A short review on approach for biodiesel production: Feedstock’s, properties, process parameters and environmental sustainability

Over the past few decades, an increase in industrialization and the population have been indicated as being critical to the need for energy. Higher pollution levels and rising fuel prices go hand in hand with the increasing demand for renewable energy. Apart from global warming, research interests were encouraged to develop sustainable fuels such as biodiesel, which is a renewable and sustainable substitute for petroleum diesel fuel. Biodiesel is produced from either oil derived from vegetables or animal fats via a catalytic transesterification process. Biodiesel has a few important advantages, such as stronger lubricity, a low level of toxicity, being derived from renewable feedstock, bio-degradability, low sulphur content, and lower levels of exhaust emissions than petroleum diesel fuel. In this comprehensive review, the approach to the biodiesel production process is discussed. This paper also described the benefits and drawbacks of biodiesel, the choice of different feedstock’s, factors (process parameters) that affect biodiesel yield, and research conducted on various aspects of biodiesel properties in various regions around the world. Additionally, it explains the various biodiesel blends, economic and sustainable development, and future challenges associated with biodiesel production.

High Sulfur in Primitive Arc Magmas, Its Origin and Implications

Sulfur contents in 98.5% of melt inclusions (MI) from calc-alkaline subduction basalts do not exceed 4000 ppm, whereas experimentally established limits of sulfur solubility in basaltic melts with high fO2 (characteristic of subduction zones, e.g., QFM + 2) surpass 14,000 ppm. Here we show that primitive (Mg# 62-64) subduction melts may contain high sulfur, approaching the experimental limit of sulfur solubility. Up to 11,700 ppm S was measured in olivine-hosted MI from primitive arc basalt from the 1941 eruption of the Tolbachik volcano, Kamchatka. These MI often contain magmatic sulfide globules (occasionally enriched in Cu, Ni, and platinum-group elements) and anhydrite enclosed within a brown, oxidized glass. We conclude that the ubiquitous low sulfur contents in MI may originate either from insufficient availability of sulfur in the magma generation zone or early magma degassing prior to inclusion entrapment. Our findings extend the measured range of sulfur concentrations in primitive calc-alkaline basaltic melts and demonstrate that no fundamental limit of 4000 ppm S exists for relatively oxidized subduction basalts, where the maximum sulfur content may approach the solubility limit determined by crystallization of magmatic anhydrite.

Сучасний досвід десульфурації сталі

Modern technological schemes of steel production do not allow to achieve low (< 0.01 % S) and ultra-low (<0.005 % S) sulfur content on the production of in the metal directly. That is why out-of-furnace steel treatment is often used to remove sulfur. Desulfurization process of steel depends on the chemical composition of the slag, the time of its formation in the ladle, metal oxidation, conditions of mixing of steel in a ladle, additional technological operations and ladle metal processing. Methods are widely used for desulfurization of steel treatment of steel with solid slag-forming mixtures, synthetic slag, lime-aluminous slag, silico-calcium and other powdered materials. Modern approaches to the process of steel desulfurization in conditions steel production are analyzed in the Study. In particular, the Ukrainian (on the example of PJSC ‘Azovstal Iron & Steel Works’ and PJSC ‘Dneprovsky Integrated Iron & Steel Works named after Dzershinsky’) and foreign (on the example of PJSC ‘Severstal’ and PJSC ‘Magnitogorsk Iron & Steel Works’) experience of desulfurization under oxygen converter production. The use of technological complexes ‘Installation of pig iron desulfurization steel making unit’ and ‘Cast iron desulfurization installation steel making unit is ‘oven-bucket’ installation’ provides a deeper desulfurization of steel, the possibility of optimizing the cost of steel production, expands range of scarce products and eliminates a number of restrictive conditions that complicate current production. The analysis of steel C80D desulfurization process is given in the conditions of JSC ‘Moldova Steel Works’, in which partial sulfur removal occurs in an arc steel making furnace, and the ultra-low content is achieved by creating a highly basic refining slag in the process out-of-furnace processing of steel. The study of the kinetics of the desulfurization process of 20GL steel in the conditions of JSC ‘Tashkent Mechanical Plant’ with the use of solid slag-forming mixtures and modification of steel with rare-earth metals is analyzed. The issue of desulfurization of electric steel in the conditions of OJSC ‘Byelorussian Steel Works’ with injection of powdered materials through the installation ‘Velko’ during out-of-furnace processing of steel is considered. Keywords: steel desulfurization, desulfurizer reagent, degree of desulfurization, cast iron desulfurization installation, out-of-furnace processing of steel, ‘‘oven-bucket’’ installation.

Real-Time Electrical Conductivity Monitoring and Correlation with Sulfate Release and Acid Mine Drainage Potential from a Gold/Silver Paste Tailing Storage

Safe disposal of tailings as high-density thickened tailings or paste tailings can reduce the environmental risks of conventional tailings deposits, reduce water use, minimize tailings storage facility footprints, reduce the potential for acid mine drainage (AMD), and minimize risks of failure, among other advantages. In the dewatering process, the addition of flocculants is key to improving the sedimentation of the tailings and the formation of a compact paste. Despite the environmental and operational advantages of using paste tailings, it is not clear how the chemical nature of coagulants and flocculants could influence the discharge of toxic elements (salts and metals) from tailings after storage. In this study, we show the results of the real-time evaluation of the release of polluting runoffs from a paste tailings deposit. To do this, we analyzed paste tailing samples for AMD potential through static and kinetic tests and monitored the electrical conductivity and real-time pH, evaluating the correlation with the sulfate in the thickener and downstream from the tailings deposit. Tailing samples have low sulfur content (<2%) and low acid-generating potential. Moreover, there is no evidence of a significant positive correlation (Pearson’s coefficient r < 0.8) between the sulfate concentrations with the pH or EC. Thus, the chemical nature of the paste tailings prior to discharge has no direct impact on the release of sulfate-rich runoffs from the tailings after its storage. This indicates that the tailings paste at the evaluated site is chemically stable in the short term.