Arsenopyrite
Mostrando 1-12 de 12 artigos, teses e dissertações.
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1. Arsenic mobilization from sulfidic materials from gold mines in Minas Gerais State
Acid drainage results from exposition of sulfides to the atmosphere. Arsenopyrite is a sulfide that releases arsenic (As) to the environment when oxidized. This work evaluated the As mobility in six sulfidic geomaterials from gold mining areas in Minas Gerais State, Brazil. Grained samples (<2 mm) were periodically leached with distilled water, during 70 day
Química Nova. Publicado em: 2008
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2. Processos metalogenéticos em ambientes de arco magmático tipo andino, caso de estudo: mineralizações da região dos Andes Patagônicos setentrionais do Chile / Metallogenic processes in andean volcanic arc setting, study case: mineralizations in the Chilean North-Patagonion Andes
In the Patagonian Andes region between 41 and 44° S extensive and continuous plutonic rocks of the North-Patagonian Batholith north segment are exposed. During their evolution most of the granitic rocks were emplaced in metamorphic rocks and other parts were emplaced in Late Jurassic-Berriasan volcanic rocks, Early Cretaceous sedimentary and volcanic rocks,
Publicado em: 2008
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3. Leaching of a gold bearing partially roasted sulphide. Laboratory scale studies
This research aimed at defining a route for recovering precious metals from a very heterogeneous gold bearing sulphide and arsenide concentrate that was partially roasted and dumped by the 1960s when Santo António mine closed. Gold occurs in this concentrate as free particles in the range of 10-100 mum, most of them still enclosed in the pyrite and arsenopy
Materials Research. Publicado em: 2001-10
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4. Estudo eletroquímico das interações entre sulfetos de ferro / Electrochemical study of iron sulphides interactions
The electrochemical behavior of iron sulfides, pyrite, pyrrhotite and arsenopyrite was studied in acetic acid/sodium acetate buffer, pH = 4.5. The investigations included the dissolution of minerals (isolated and mixed in pairs) and the studies of the deposition of silver ions on the electrode surfaces, taking into account the semiconducting properties of ea
Publicado em: 1999
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5. Mineralização aurifera de Lages-Antonio Dias, Ouro Preto-MG controles lito-estratigraficos e estruturais
The Lages-Antônio Dias area is eomprised within the Ouro Preto mountain range, Minas Gerais. The area hosts a number of aneient, abandoned gold mines; Chieo Rei, Scliar and Duas Bocas being among the largest deposits. Detailed geologieal mapping of both the Lages-Antônio Dias area (1:2000) and these mines (1:250 se ale) showed that gold is associated with
Publicado em: 1999
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6. Caracterização da geometria de zonas de alteração hidrotermal - Estudo de caso no deposito aurifero de Brumal, Quadrilatero Ferrifero, Minas Gerais
The Brumal gold deposit is located in the northeastern portion of the Quadrilatero Ferrifero region. It is encIosed within an Archaean voIcano-sedimentary sequence (i.e., Nova Lima Group). Regional host rocks comprise two distinct greenstone assemblages, from bottom to top: (i) mafic to ultramafic volcanics and (i i) cIastic and chemical sediments. At least
Publicado em: 1999
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7. Geoquimica e impacto ambiental do arsenio no Vale do Ribeira (SP-PR)
The sedimentary and volcanic rocks of the Ribeira Valley, in the Apiaf FoId Belt, host a variety of PbZn deposits, which were formed by singenetic (Perau-type) and epigenetic (Panelas-type) models. Long-term mining activities originated a toxic contamination by arsenic in the stream sediments of the Ribeira de Iguape river that drains the region. The purpose
Publicado em: 1997
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8. Intrusões sub-vulcanicas alcalinas e lamprofiros nas mineralizações auriferas do Greenstone Belt do Rio Itapicuru, Bahia : petrografia, geoquimica e inclusões fluidas
At the Fazenda Maria Preta (FMP) and Mari (MR) gold deposits, in the Rio Itapicuru greenstone belt (RIGB), two host volcanic rocks and a mafic dyke were studied and reclassified. In the Corpo H body (FMP) the host roek is called silicified dacite, but in this worlc, based on the mineralogy and textural ftamework, the roek is reclassified as alkali-feldspar s
Publicado em: 1997
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9. Caracterização tectono-metamorfica do deposito aurifero Ambrosio, Greenstone Belt do Rio Itapicuru - Bahia
The Ambrósio lode gold deposit, located in the northem sector ofthe lower Proterozoic (2.200 to 2.000 Ma) Rio Itapicuru greenstone belt, northeast Brazil, is enclosed within a narrow belt ofhighly deformed supracrustals, tightly squeezed between two syn-tectonic granitic batholiths (pedra Alta and Ambrósio domes). The deposit is hosted at the contact of am
Publicado em: 1996
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10. Oxidative Dissolution of Arsenopyrite by Mesophilic and Moderately Thermophilic Acidophiles †
The purpose of this work was to determine solution- and solid-phase changes associated with the oxidative leaching of arsenopyrite (FeAsS) by Thiobacillus ferrooxidans and a moderately thermoacidophilic mixed culture. Jarosite [KFe3(SO4)2(OH)6], elemental sulfur (S0), and amorphous ferric arsenate were detected by X-ray diffraction as solid-phase products. T
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11. Potential Role of Thiobacillus caldus in Arsenopyrite Bioleaching
We investigated the potential role of the three strains of Thiobacillus caldus (KU, BC13, and C-SH12) in arsenopyrite leaching in combination with a moderately thermophilic iron oxidizer, Sulfobacillus thermosulfidooxidans. Pure cultures of T. caldus and S. thermosulfidooxidans were used as well as defined mixed cultures. By measuring released iron, tetrathi
American Society for Microbiology.
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12. Molecular genetics of Thiobacillus ferrooxidans.
Thiobacillus ferrooxidans is a gram-negative, highly acidophilic (pH 1.5 to 2.0), autotrophic bacterium that obtains its energy through the oxidation of ferrous iron or reduced inorganic sulfur compounds. It is usually dominant in the mixed bacterial populations that are used industrially for the extraction of metals such as copper and uranium from their ore