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Showing 1 to 18 of 18 for “"covellite"”.
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Rates of reaction of covellite and blaubleibender covellite with ferric iron at ph 2.0
… samples (100-200 mesh) of blaubleibender covellite and covellite with 10⁻³ m ferric iron in a pH 2 solution were determined at 25, 35, and 50°C. Ferrous and cupric ion concentrations of the run solutions suggest that parallel reactions oxidized the sulfur to either elemental sulfur or to …
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The anodic dissolution of covellite in acidic, chloride solutions
… on a stationary, synthetically produced, covellite electrode in acidic, chloride solutions at ambient conditions to investigate the dissolution behaviour of the mineral over a surface potential range from the open circuit potential (OCP) to about 0.62 V (vs. SHE). The electrode was mounted …
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Mineralogical, textural, and paragenetic studies of selected ore deposits of the Southeast Missouri lead-zinc-copper district and their genetic implications
… siegenite, bornite, bravoite, blaubleibender covellite, covellite, gersdorffite, digenite, enargite, tennantite, dickite, and malachite.</p> <p>The paragenesis indicates that the ore solutions evolved in the following order: (1) Cu-rich, (2) Co-Ni-rich, (3) Pb-Zn-rich, and (4) Fe-rich. …
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The Electronic Structure and Reactivity of Sulfide Surfaces: Combining Atomic-Scale Observations with Theoretical Calculations
… electronic structure of clean pyrite {100} and covellite {001} surfaces have been investigated in ultra-high vacuum (UHV) for the purpose of understanding the nature of sulfide surface reactivity. Using primarily scanning tunneling microscopy and spectroscopy (STM/STS), the electronic structure …
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Hydrophobic Forces in Flotation
… 109 degrees. The mineral systems studied include covellite (CuS), sphalerite (ZnS) and hornblende (Ca₂(Mg, Fe)₅(Si₈O₂₂)(OH,F)₂). The collector used for all the mineral systems studied was potassium ethyl xanthate (KEX). For the covellite-xanthate system, a biopotentiostat was used in conjunction …
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I. An oxygen-17 NMR study on oxygen exchange in yttrium barium(2) copper(3) oxygen(7-x). II. Synthesis of transition metal polysulfide complexes from metal powders
Covellite, $\rm Cu\sp{I}\sb2(S\sb2)Cu\sp{II}S$ (T$\sb{\rm c}$ = 1.66 K) and $\rm YBa\sb2Cu\sp{II}\sb2Cu\sp{III}O\sb{7-x}\ (T\sb{c}$ = 92 K) are similar in that both are superconductors containing layered structures and mixed valent copper centers. Our studies on YBa$\sb2$Cu$\sb3$O$\sb{\rm 7-x}$ …
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Kinetic Studies of Sulfide Mineral Oxidation and Xanthate Adsorption
… (pure and nickel activated), chalcocite and covellite were studied in 10-4 M ethylxanthate solution at pH 6.8 at temperatures in the range of 22 – 30 0C. The Tafel studies showed that xanthate adsorbs as dixanthogen (X2) on pyrite and pyrrhotite, nickel dixanthate (NiX2) on nickel-activated …
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A study of the vein copper mineralization of the Virgilina district, Virginia and North Carolina
… in decreasing order of abundance is malachite, covellite, cuprite, digenite, hematite, chalcopyrite, chalcocite/ djurleite, azurite, spion kopite, and yarrowite. This represents the first reported occurrence of djurleite, anilite, hessite, spionkopite, and yarrowite in the area. Lamellar …
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In-situ Wachstumsuntersuchungen beim reaktiven Anlassen von Cu, In Schichten in elementarem Schwefel
… diese Phase unter dem Verbrauch von Schwefel in Covellite um.Für Proben mit Kupferüberschuss konnte eine Wachstumskinetik proportional zur Temperatur beobachtet werden. Dieses Verhalten wurde durch eine stress-induzierte Diffusion als dominierenden Reaktionsmechanismus interpretiert. Dabei werden …
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Geology and mineralization in the vicinity of the Morning Star precious-metal deposit of the Ivanpah Mountains, San Bernardino County, California
… around early electrum or as intergrowths with covellite and acanthite during secondary mineralization. Textures and compositions of the electrum and Ag+Au-sulfides indicate Au and Ag remobilization was isochemical in the lower portions of the deposit, while remobilization at upper levels of the …
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Re-evaluation of Kombat-style mineralisation and implications for exploration in the Otavi mountainland, Namibia
… ore minerals such as chalcopyrite, bornite, covellite, and galena with minor chalcocite, sphalerite, and pyrobelonite, for the Cu-Pb MVT-type ores. For the Fe-Mn ores, hausmannite, hematite with minor, manganite may be are considered.
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Nonstoichiometry of chalcocite in water-xanthate systems
… pertain to chalcocite, djurleite, anilite and covellite. Calculations were completed for cases where oxidation of the sulfur proceeded to i) elemental sulfur, ii) thiosulfate, iii) sulfate and iv) destabilized sulfate. Stability regions for each copper sulfide were shown to be dependent on both …
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Assessment of copper recovery from leaching of microwave pre-treated tailing from the Otjihase mine
… material in the form of sulphide minerals only, covellite (CuS) and chalcopyrite (CuFeS2). Dry mine tailings of particle size -75μm were subjected to microwave pre-heating for 6 minutes in a domestic microwave oven for varying microwave intensities. This was followed by leaching with 0.5M …
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An investigation into the ferric leaching of chalcopyrite : a sub-process in the bioleaching of chalcopyrite
… sulfur or iron deficient polysulfide like covellite (Klauber et al. , 2001 , Parker et al., 1981 , Munoz et al, 1976, Warren et al., 1985 and Parker et al., 1981). Recent research has suggested that different passivating layers are formed during the various stages of chalcopyrite leaching. …
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Geochemistry and origin of the Asimotrypes carbonate hosted mesothermal gold deposit, Pangeon mountain, N. Greece
… pyrrhotite, tetrahedrite-tennantite, marcasite, covellite and malachite. Gold is either refractory occurring mainly in arsenopyrite and to a lesser extent in Aspyrite, or free in the oxide minerals.<br/><br/>Three types of fluid inclusions (with subtypes) were recognised based on constituent …
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Non-hydrolytic Sol-gel (NHSG) Synthesis of Transition Metal Sulfides and Theoretical Investigations
… chalcocite, djurleite, low digenite and covellite, was achieved by fine tuning synthetic parameters. In addition, a continuous phase evolution from copper rich phases towards copper deficient phases between chalcocites and djurleite was observed. All polymorphs could be obtained as …
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Deportment of radionuclides in copper concentrate from Olympic Dam
… of RNs in high surface area minerals such as covellite and molybdenite have been identified, as well as electrokinetic effects responsible for substantial uptake of RNs on the surface of sulphide minerals. Additionally, diffusion experiments were performed on synthetic minerals to determine …
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Non-metallic nanostructures for light-driven chemistry and catalysis
… in another form of copper sulfide, CuS, known as covellite. CuS has long presented a puzzle in terms of the oxidation state of copper, the structure of the lattice, and whether or not the material has copper vacancies and associated free carriers. This also raises questions about the near-infrared …