Papers by Keyword: Sulfide

Abstract: In this work, the Fe-Cr-Mo-V-W-C-MoS₂ composites were fabricated using the powder metallurgy process. The uniaxial cold compaction was used to produce green specimens with the density of 6.3 g/cm³. Subsequently, the specimens were sintered at temperatures of 1150 and 1200 °C for 45 min in a vacuum furnace. Sintered specimens were cooled down in the furnace with N₂ at a cooling rate of 0.1 °C/s. The influence of MoS₂ addition on the density, hardness and microstructure were investigated. Density and hardness of composites were improved due to MoS₂ addition, especially, 5 wt.% MoS₂ addition and sintering at 1200 °C. The dissociation of MoS₂ contributed to the formation of sulfide phases and hard carbide particles within the composites. Sulfide phases such as FeS, CrS and other sulfides were detected by x-ray diffraction analysis. The reciprocating wear test was used to study the effect of MoS₂ addition on friction and wear resistance of composites. The synergy of FeS and CrS contained in the compacted layer and hard carbide particle formation within the matrix were expected to enhance tribological properties of composites by decreasing friction coefficient and improving wear resistance.

Abstract: Sulfide was used as solid lubricant, and MoS₂ was popular. It was used industry as powder shape. Sulfur as oil additive; ZDDP, MoTDC were also well known. These composites make tribofilm which prevent seizure, scoring and some tribological troubles. In this paper, sulfides were synthesized by powder metallurgy technics. In addition, these sulfides were mixed with bronze powders and sintered as cylindrical specimen. As a result of the friction test in the lubricated condition, tribofilm were covered with specimen surface. By XPS observation, sulfides and oxides were detected on the specimen surface. In the test, additive was not contained in the lubricant because PAO as base oil was adapted. However, sulfide in the specimen affect the making the tribofilm, especially when bornite (Cu₅FeS₄) was used.

Abstract: A quantitative ion chromatographic analytical method for the continuous determination of the sulfite and sulfide in gypsum and gypsum products is proposed. This paper established a determination method removal interference with each other between sulfite and sulfide that measure sulfite and sulfide content respectively. A set of calibration graphs for standards with different concentration ranges with indicate a good linear regression.The method presents good repeatability because in all cases the observed RSD was below 1% through two chromatographic parameters both of the retention time and the area of the analytical signal. The accuracy of the method was evaluated through recovery assays. The recoveries varied from93.9% to 105.7% depending on the anion, indicating that the extraction of the analytes was good enough to de used for the determination of the studied anions in gypsum sample.

Abstract: The sulfide tailings is the main type of non-ferrous metals mine tailings, in which the sulfides could react with air, rain water and microorganism, etc. and then release some ions through a series of complex chemical interactions. The heavy metal ions leaching from tailings will cause serious pollution to the environment of mine region. The release mechanisms and effect factors of heavy metals ions from sulfide tailings are summarized in this paper.

Abstract: A simple and rapid spectrophotometric method for flow injection determination of sulfite in tan wastewater is described. It was based on the fade reaction of sulfide ion with Ag (I)- (5-Bromo-2-pyridylazo)-5-diethyl-aminophenol (5-Br-PADAP) in NaAc-HAc medium. The optimum conditions allow a linear calibration range of 0.01-1.10 μg ml^-1 sulfide ion. The detection limit is 0.0043 μg ml-1 (S/N=3), and the relative standard deviation for night replicate measurements is 2.1% for 0.5μg ml^-1 of sulfide ion. The procedure has been applied to the determination of sulfide in tannery wastewater. The results were in good agreement with those obtained by methylene blue spectrophotometric method.

Abstract: By using the optical microscopy, scanning electron microscopy, X-ray fluorescence spectrum analyzers and spectrum analyzers, cracking of automotive stamping parts were researched and analyzed. The results showed that the fracture morphology of grainy layered fracture was caused by a long strip of sulfide inclusions.

Abstract: In this case study, the corrosion failure analysis of high-pressure boiler water-wall tubes in a power plant was investigated by means of the chemical analysis, metallographic examination and scanning electron microscope (SEM) observation. Energy dispersive spectroscopy (EDS) was used to examine the changes of test materials and corrosion products. Based on the failure process of the boiler water-wall tubes and the experimental results, a conclusion was drawn that the failure of water-wall tubes was mainly caused by pitting corrosion. Sulfide and chloride attack was the major cause of localized pitting corrosion on the inner surface, and the outer surface damage was mainly due to the synergism of high temperature sulfide corrosion and flue gas erosion.

Abstract: Make 5-methoxy-2-mercapto-imidazo[4,5-b]pyridine and 2-chloro-3,5-dimethyl-4-methoxy-pyridine hydrochloride as the starting materials, in alkaline conditions, use nucleophilic substitution to generate the prochiral sulfide: 2-[2-(4-methoxy-3 ,5-dimethyl-pyridine) methylmercapto]-5-methoxy-imidazo [4,5-b] pyridine. After recrystallization twice, gain the product with the yield of 80%, and the purity of 99.6% and above. Then make D-(-)-diethyl tartrate and tetraisopropyl titanate as the chiral reagents, in alkaline conditions, use cumene hydroperoxide oxide to oxidize prochiral sulfide, for synthesis of (S)-Tenatoprazole, and the results showed that when, the reaction temperature was , and reaction time was 20h, the result was the best.

Abstract: A task of a refractory oxide copper ore in Yunnan has been studied, the grade of copper is 2.76% in crude ore. This ore has high oxidation and deep combination, the oxidation ratio is 42.32% and the combination ratio is 33.01%, so it is difficult oxide copper. Because the sulfide copper in crude ore containing 21.27%, so by experimental research, we decided to adopt the process of floating copper sulfides, and then sulfide oxide copper. In the flotation of oxidized copper minerals, we take the process of desliming, the copper minerals have recycled efficiently, while making a small precious metal--silver has been associated enrichment. Through closed-circuit test, we obtained the final concentrate, which the grade of copper is 20.38%, the recovery of copper is 65.44% and the grade of silver is 80.15g/t.

Abstract: The gold-sulfide deposit Southern Ashaly is localized in carbonaceous terrigenous formation (black shale strata) of the middle carboniferous (Bukon suite, which is the ore-hosting for super large deposit Bakyrchik). The Southern Ashaly is at the exploration stage and according to preliminary estimates of the expected resources belongs to a large deposit in scale. Ore gold mineralization of such level as Southern Ashaly in southwestern Kalba is found for the first time and gives hope for the discovery of such objects in the Boko Vassilyevskoye ore field. Ore-hosting at the field Southern Ashaly is carbonaceous terrigenous formation of the middle carboniferous, with no visible signs of volcanic formations. But, it was revealed, at microscopic research by us, paragenetic relation of the gold mineralization with small intrusions of plagiogranites and zones of plagiogranite porphyry dykes and found volcano-sedimentary rocks (aleuritic tuffsandstone, tuff breccia) which have undergone hydrothermal-metasomatic changes. The vein-disseminated gold-sulfide mineralization is associated with beresitizated plagiogranites and plagigranite-porphyries and hydrothermally altered tuff sandstones, tuff breccia and carbonaceous shales. Southern Ashaly unlike Bakyrchik deposit which contains invisible gold in sulfides, all the gold is concentrated in the pyrite mainly in the form of micro-sized (1-5 µm or less) in arsenopyrite is noted rarely.