نتایج جستجو برای: pyrite

تعداد نتایج: 3387  

2015
Ali Ahmadi

Environmentally and technologically sulphur is a deleterious constitute in coal which makes it unsuitable for use in metallurgical industries unless the sulphur level can be reduced to the tolerable limit. Characterization of the various forms of sulphur and their associations in coal is an essential issue to find and propose a suitable desulphurization method. In this research, to evaluate sul...

Journal: :Applied and environmental microbiology 1993
P Devasia K A Natarajan D N Sathyanarayana G R Rao

Thiobacillus ferrooxidans cells grown on sulfur, pyrite, and chalcopyrite exhibit greater hydrophobicity than ferrous ion-grown cells. The isoelectric points of sulfur-, pyrite-, and chalcopyrite-grown cells were observed to be at a pH higher than that for ferrous ion-grown cells. Microbe-mineral interactions result in change in the surface chemistry of the organism as well as that of the miner...

2014
Milena Becelic-Tomin Bozo Dalmacija Ljiljana Rajic Dragana Tomasevic Djurdja Kerkez Malcolm Watson Miljana Prica

Pyrite ash (PA) is created by burning pyrite in the chemical production of sulphuric acid. The high concentration of iron oxide, mostly hematite, present in pyrite ash, gives the basis for its application as a source of catalytic iron in a modified Fenton process for anthraquinone dye reactive blue 4 (RB4) degradation. The effect of various operating variables such as catalyst and oxidant conce...

2017
Bjørn Buchardt Mary Anne Holmes

The initial transgressive phase at the Leg 144 Guyots is characterized by a typical association of sedimentary facies (from bottom to top): in situ weathered volcanic rocks; variegated clays, partly pyritic; gray clay, pyritic, homogeneous, or mottled; black clay, peaty, laminated, or bioturbated; and marine argillaceous limestone. Site 877 at Wodejebato Guyot represents the typical development...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2017
Virgil Pasquier Pierre Sansjofre Marina Rabineau Sidonie Revillon Jennifer Houghton David A Fike

The sulfur biogeochemical cycle plays a key role in regulating Earth's surface redox through diverse abiotic and biological reactions that have distinctive stable isotopic fractionations. As such, variations in the sulfur isotopic composition (δ34S) of sedimentary sulfate and sulfide phases over Earth history can be used to infer substantive changes to the Earth's surface environment, including...

Journal: :iranian journal of chemistry and chemical engineering (ijcce) 2013
behzad shahbazi bahram rezai sayed mohammad javad koleini mohammad noparast

in this research, the effect of bubble surface area flux, sb, and particle size on flotation rate constant, k, of pyrite (fes2) particles was studied using bubble-particle interactions. the bubble-particle collision, attachment and detachment efficiencies were calculated under different flow regimes. the k increased with increase in the collision efficiency and decrease in the detachment effici...

2007
Olesya Lazareva Thomas Pichler

To understand the mineralogical association, concentration, and distribution of arsenic (As) in the Hawthorn Group, the chemical and mineralogical composition of 362 samples that were collected from 16 cores in southwestern Florida were examined in detail. In the study area, the Hawthorn Group consisted primarily of a basal carbonate unit (the Arcadia Formation) and an upper siliciclastic unit ...

2011
Sune G. Nielsen Matt Goff Stephen P. Hesselbo Hugh C. Jenkyns Doug E. LaRowe Cin-Ty A. Lee

This paper presents the first study of Tl isotopes in early diagenetic pyrite. Measurements from two sections deposited during the Toarcian Ocean Anoxic Event (T-OAE, 183 Ma) are compared with data from Late Neogene (<10 Ma) pyrite samples from ODP legs 165 and 167 that were deposited in relatively oxic marine environments. The Tl isotope compositions of Late Neogene pyrites are all significant...

2013
Gabriella B. Kiss Federica Zaccarini

The NE Hungarian Darnó Hill is geologically complex; it is composed of an accretionary mélange complex, which contains Permian, Triassic and Jurassic sedimentary and magmatic blocks. The succession can easily be correlated with the NW Dinarides, using evidences of the different evolutionary stages of the Neotethyan Ocean (rifting, marginal basin opening, closure). Several ore indications are kn...

2008
Thomas Algeo Yanan Shen Tonggang Zhang Harry Rowe T. K. T. Nguyen

[1] A marine Permian-Triassic boundary (PTB) section at Nhi Tao, Vietnam, contains a series of at least 9 pyritic horizons characterized by concurrent decreases in pyrite S(dSpy) and carbonate C-isotopic compositions (dCcarb). The first and largest of the events that precipitated these pyritic horizons was coincident with the Late Permian mass extinction, while subsequent events were generally ...

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