Sulfur elemental from sulfide minerals

Flotation Reagents. Only one sulfide mineral flotation collector is manufactured from phosphine, ie, the sodium salt of bis(2-methylpropyl)phosphinodithioic acid [13360-78-6]. It is available commercially from Cytec Industries Inc. as a 50% aqueous solution and is sold as AEROPHINE 3418A promoter. The compound is synthesized by reaction of 2-methyl-1-propene [115-11-7] with phosphine to form an iatermediate dialkylphosphine which is subsequently treated with elemental sulfur [7704-34-9] and sodium hydroxide [1310-73-2] to form the final product (14). The reactions described ia equations 10 and 11... 

Berner (3J5.) attributes monosulfide preservation in Black Sea sediment to insufficient elemental sulfur (polysulfides) to completely convert FeS to FeS2 (Equation 3). Both sulfide minerals in sediment from Walker Lake are typically depleted in 34S with a 834Smin average of -15%o. At a few depths, however, 834S values are similar or enriched in 34S relative to the sulfate in the modern lake (834S +10%o calculated from pore-water sulfate data). 

Iron monosulfides comprise about 20% of the iron sulfide minerals in the noneuxinic sediment and about 50% in the euxinic sediment. Their greater preservation in the euxinic sediment, as in sediment from Walker Lake, is probably a result of insufficient elemental sulfur formation in this extremely reducing environment. Seasonally aerobic conditions at the sediment-water interface of the noneuxinic sediment would promote elemental sulfur formation from the oxidation of H2S that accumulates in pore water. 

Sulfur occurs widely in Nature as the element, as H2S and S02, in numerous sulfide minerals, and in sulfates such as the many forms of gypsum (CaS04-2H20). It occurs in crude oils and in coal and as H2S in natural gas, from which it is recovered in large quantities via the reaction... 

Other less common elements recorded in these analyses are tin, chromium, and nickel. The tin is found among some of the opaque constituents (minerals) and is thought to be present as the mineral cas-siterite (Sn02), which is reportedly (17) associated with sulfide mineralization. Less is known about the location of the chromium, which may be a minor element in more than one mineral, e.g., pyrite and calcite. Nickel, on the other hand, is associated with sulfur, as can be shown in the X-ray spectra (Figure 10) obtained from a diamond-shaped mineral fragment. The analysis was obtained in the reflection (SEM) mode on the STEM, which excluded the recording of an electron diffraction pattern. The mineral tentatively is identified as millerite, a nickel sulfide (NiS) with no iron and a 1 1 ratio of nickel to sulfur. However, these conclusions must be considered as tentative until positive identification of the nickel sulfide is possible. 

Polysulfides can be generated via two major pathways. First, polysulfides can be formed by the oxidation of dissolved sulfide and sulfide minerals(l, 2). Second, they can be formed by the reaction of elemental sulfur with bisulfide ion(35). Polysulfide levels can be predicted for the second process as described in previous studies(, 36-38). Equilibrium calculations as described in a previous study(22) were performed for the polysulfide levels in these samples. The ratio of S(0) experimental to S(0) calculated for all samples from Great Sippewissett were 0.145 (4-8 cm), 0.137 (8-13 cm) and 0.128 (23-28 cm). Because these ratios are less than 1.0, these results indicate that polysulfides should form primarily from the reaction of bisulfide ion with elemental sulfur(5) rather than sulfide oxidation. This data set is... 

Sulfur, another Group VIA element, occurs in sulfate and sulfide minerals. Free sulfur, Sg, occurring in deep underground deposits is mined by the Frasch process. Sulfur is also produced by the Claus process, in which hydrogen sulfide (obtained from natural gas and petroleum) is partially burned. Most of the sulfur is used to prepare sulfuric acid by the contact process. In this process, sulfur is burned to sulfur dioxide, SO2, which in the presence of a catalyst and oxygen forms sulfur trioxide, SO3. This oxide dissolves in concentrated sulfuric acid, which when diluted with water gives additional sulfuric acid. Sulfuric acid is the most important compound of sulfur. 

Both sodium sulfide and the bisulfide are used in the flotation process for copper minerals and as a depilatory for animal liides (see Copper Copper ALLOYS Leather). Also, sodium polysulfide can be produced from Na2S, and elemental sulfur can be produced if H2S is generated as an intemiediate. 

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