Sulfide occurrence

Removal of sewer biofilm and deposits by flushing and use of a cleaning ball for detachment of biofilm and resuspension of sewer sediments are examples of mechanical methods for reducing sulfide occurrence. 

Pomeroy, R.D., J.D. Parkhurst, J. Livingston, and H.H. Bailey (1985), Sulfide occurrence and control in sewage collection systems, Technical Report, US Environmental Protection Agency, USEPA 600/X-85-052, Cincinnati, OH. 

Synonym antimony sesquisulfide antimony sulfide Occurrence and Uses... 

Friedman, G.M. (1994) Dolostone-hosted sulfide occurrences in Silurian strata, Appalachian basin of New York. In Sediment-Hosted Zn-Pb Ores (Eds Fontbote, L. Boni, M.). Soc. Geol. Appl. Miner. Deposits Spec. Publ., 10, 77-88. 

Characteristics of hydrogen sulfide, occurrence in petroleum industry, protection, and rescue procedures. 

Manus Basin is a back-arc basin located north of the New Britain island arc that consists of NE-SW trending ridge segments offset by transform faults. On the Manus Spreading Center in central Manus Basin the Vienna Woods hydrothermal field consists of a 300 m-diameter sulfide mound with an extensive foresf of active and inactive sphalerite-barite-rich, sulfide-sulfate-oxide chimneys up to 15 m-long atop it. Vent fluids from one of the active chimneys reach temperatures as high as 302°C. In the eastern Manus Basin, two important hydrothermal fields are known. The PACMANUS field includes discontinuous sulfide occurrences over a 3 by 0.8 km area and active venting of unknown nature. Volcanic rocks are andesitic to rhyodacitic. 

Occurrence of rhenium and molybdenum together in nature is a consequence of the similarities of these elements. Both elements have a high affinity for sulfide ion. Moreover, the radii of Re" " and Mo" ", 0.74 nm and 0.70 nm, respectively, ate almost identical, so that ReS2 [12038-63-0] and M0S2 have similar crystal stmctures with almost identical dimensions (see Molybdenumcompounds). 

Dimethyl sulfoxide occurs widely at levels of <3 ppm. It has been isolated from spearmint oil, com, barley, malt, alfalfa, beets, cabbage, cucumbers, oats, onion, Swiss chard, tomatoes, raspberries, beer, coffee, milk, and tea (5). It is a common constituent of natural waters, and it occurs in seawater in the 2one of light penetration where it may represent a product of algal metaboHsm (6). Its occurrence in rainwater may result from oxidation of atmospheric dimethyl sulfide, which occurs as part of the natural transfer of sulfur of biological origin (7,8). 

Occurrence. The metal sulfides, which are scattered throughout most of the world, have been an important source of elemental sulfur. The potential for recovery from metal sulfides exists, although these sources are less attractive economically and technologicaky than other sources of sulfur. Nevertheless sulfide ores are an important source of sulfur in other forms, such as sulfur dioxide and sulfuric acid. 

Occurrence ndPreparation. Carbonyl sulfide is formed by many high temperature reactions of carbon compounds with donors of oxygen and sulfur. A principal route is the foUowiag reaction (30) ... 

Epithermal base-metal vein-type deposits are characterized by the abundant occurrence of sulfides (chalcopyrite, pyrite, sphalerite, galena), and a scarcity of Au-... 

Figure 1.107 shows the frequency of 8 C of carbonates from epithermal Au-Ag vein-type deposits and that from base-metal vein-type deposits. The carbonates are divided into two types type A and type B. Type A is characterized by (1) abundant occurrence in each deposit (2) coexistence with sulfide minerals and (3) large grain size. Main carbonate minerals are rhodochrosite and Mn calcite, whereas calcite is the main carbonate mineral for type B. Mn-carbonates of type A occur in Pb-Zn-Mn vein-type deposits. Type B is characterized by (1) poor amounts in each deposit (2) coexistence... 

This type of mixing could reasonably explain the occurrence of acidic alteration minerals such as kaolinite and alunite in the low-sulfidation epithermal gold vein district (e.g., Seta in northeast Hokkaido, Hishikari in southern Kyushu) (Yajima et al., 1997)... 

Aoki, M. and Nakamura, K. (1989) The occurrence of chimneys in Izena Hore No. 2 orebody and texture and mineral composition of the sulfide chimneys. Proc. JAMSTEC Symp. Deep Sea Res., 5, 197-210. 

Entry 10 shows the occurrence of 5-exo cyclization. The radical in this case is generated from an amino sulfide. This reaction requires a specific, somewhat disfavored conformation of the reactant in order for cyclization to occur. When the unsubstituted vinyl substituent was used, no cyclization occurred. However, increasing the reactivity of the double bond by adding the ester substituent led to successful cyclization. 

By far the most important ores of iron come from Precambrian banded iron formations (BIF), which are essentially chemical sediments of alternating siliceous and iron-rich bands. The most notable occurrences are those at Hamersley in Australia, Lake Superior in USA and Canada, Transvaal in South Africa, and Bihar and Karnataka in India. The important manganese deposits of the world are associated with sedimentary deposits the manganese nodules on the ocean floor are also chemically precipitated from solutions. Phosphorites, the main source of phosphates, are special types of sedimentary deposits formed under marine conditions. Bedded iron sulfide deposits are formed by sulfate reducing bacteria in sedimentary environments. Similarly uranium-vanadium in sandstone-type uranium deposits and stratiform lead and zinc concentrations associated with carbonate rocks owe their origin to syngenetic chemical precipitation. 

Minerals belonging to the category of insoluble oxide and silicate minerals are many in number. Insoluble oxide minerals include those superficially oxidized and those of oxide type. The former category comprises mainly superficially oxidized sulfide minerals, including metals such as aluminum, tin, manganese, and iron which are won from their oxidic sources. As far as silicate minerals are concerned, there can be a ready reference to several metals such as beryllium, lithium, titanium, zirconium, and niobium which are known for their occurrence as (or are associated with) complex silicates in relatively low-grade deposits. 

The copper sulfide formed on the surface of the sphalerite mineral reacts readily with the xanthate, and forms insoluble copper xanthate, which makes the sphalerite surface hydro-phobic. Such a reaction for activating sphalerite occurs whenever the activating ions are present in the solution. It is thus necessary to deactivate sphalerite (to prevent the occurrence of natural activation) in the case of some ores. With lead-zinc ores, for example, natural activation occurs due to Pb2+ in solution... 

Marttila et al. (1995) also examined the relationship between daily exposure to malodorous sulfur compounds (measured as total reduced sulfur [TRS]) from pulp production and experience of symptoms in a small population living in the vicinity of a pulp mill. The major components of the malodorous sulfur compounds are hydrogen sulfide, methyl mercaptan, and methyl sulfides. This work was initiated due to the observation that an unusually high short-term exposure to malodorous sulfur compounds (maximum 4-hour concentrations of hydrogen sulfide at 135 g/m3 [96 ppb]) led to a considerable increase in the occurrence of ocular, respiratory, and neuropsychological symptoms (Haahtela et al. 

The zinc +2 ion, with its six-coordinate radius of 0.74 A, is almost identical in size to both the magnesium (0.72) and the copper (0.73) ions, but zinc is much more polarizing than the alkaline earth metal and consequently has a well-defined, albeit limited, coordination chemistry. In keeping with the much lower hardness of Zn2+ (77 = 10.88 eV) versus Mg2+ (32.55 eV),9 zinc has a much greater affinity for softer ligands than magnesium, a fact that is also reflected in the natural occurrence of zinc as sulfide ores. 

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