Hydrothermal and supergene uranium mineralization at the Osamu Utsumi mine, Poços de Caldas, Minas Gerais, Brazil

Waber, Niklaus; Schorscher, H.D.; Peters, Tjerk

doi:10.1016/0375-6742(92)90122-o

Cited by 58 publications

(14 citation statements)

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“…2, the slight variation of the δ 34 S signatures for the SO 4 throughout the reservoir and the creek indicates that this anion derives from the same sulfur source in all sediments. The average δ 34 S value for the SO 4 for all samples is −3.03 ‰ and is within the values reported for the pyrite from the Poços de Caldas Plateau that ranges from +1.24 to −3.63 ‰ (Waber et al 1992). Considering that the SO 4 formed via oxidation of pyrite presents small or negligible sulfur isotope fractionation (Taylor et al 1984;Balci et al 2007), it may be concluded that the pyrite oxidation is the main source of sulfate.…”

Section: Sulfur Isotopic Composition Of the Sedimentsmentioning

confidence: 63%

Sulfur isotope fractionation and sequential extraction to assess metal contamination on lake and river sediments

2016

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Purpose The present study investigated lake and river sediments affected by metals from an acid mine drainage (AMD) from a former uranium mine. The role of bacterial sulfate reduction in the immobilization of contaminants was evaluated, and the analyses of acid volatile sulfide (AVS) and sequential extraction were performed. Consequently, the potential mobility and bioavailability of contaminants were established. Materials and methods Sulfur isotopic fractionation (δ 34 S), AVS, and sequential extraction procedure were used to assess the sulfate bacterial reduction and the availability of contaminants in the environment at six sampling stations. Results and discussion The δ 34 S indicated that bacterial reduction is a key process in the natural attenuation of contamination in the Águas Claras reservoir, precipitating metal sulfides. According to the USEPA criteria, adverse biological effects are expected for sample S1 (inside the reservoir) which is likely to be toxic, while for sediment S4 (in the river), the toxicity is uncertain. The other samples were classified as nontoxic, likely because of the decreased solubility of zinc sulfide. A decrease in the concentration of the contaminants downstream of the reservoir was observed. The predominance of U (0.4 %) in the labile fraction and the elevated concentrations of Zn (0.5 %) and Mn (0.7 %) in the sediments inside the reservoir raises concerns regarding the availability of these contaminants in the environment. Conclusions The main environmental impact appears to be concentrated in the Águas Claras reservoir, whereas the Antas creek does not seem to be affected by the AMD process. Although the bacterial sulfate reduction is effective in its production of sulfides capable of immobilizing the contaminants, the presence of Zn and U in the labile and reducible fraction is a matter of concern due to its long-term bioavailability. Thus, continuous monitoring of the redox potential of the waters and sediments, mainly in the reservoir, is recommended in order to assess and possibly prevent later dissolution of sequestered contaminants.

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Section: Sulfur Isotopic Composition Of the Sedimentsmentioning

confidence: 63%

Sulfur isotope fractionation and sequential extraction to assess metal contamination on lake and river sediments

2016

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“…The CUM uranium deposit is defined as a mineralization of U-Th-Zr-Mo-REE (rare earth elements), composed mainly of uranium black oxides (uraninite and pitchblende -UO2), which is occasionally accompanied by cofinite (U 4+ ,Th)(SiO4)1-x(OH)4x. The mineralogy of the ore consists of: sulfide minerals, mainly pyrite FeS2 and rarely galena PbS and sphalerite ZnS; zirconium minerals, generally zircon-Zr SiO4; minerals containing Mo, mainly jordisite MoS2 and ilsemanite Mo3O8.nH2O; fluorite CaF2 and REE phases (Schorscher and Shea, 1992;Waber et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

Distribution of major and trace elements in bottom sediments of the Taquari River Basin, Caldas municipality (Brazil)

2019

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The Taquari River Basin, located in Poços de Caldas Alkaline Complex, in the southern portion of Minas Gerais state, Brazil, is situated in an old volcanic caldera. Due to its chemical and radiological characteristics, it is an area of economic and mineral interest, and is also home to diverse flora and fauna systems. In its surroundings, there are agricultural areas, industries (active and inactive) and urban and rural centers. This work investigated the total and potentially bioavailable concentrations of major and trace elements for the evaluation of geogenic and anthropogenic contamination potentials in the water bodies. The results show that there is an anthropogenic contribution (fertilizers and mining tailings) in some sectors of the Taquari River Basin, generating possible concerns regarding the quantity of elements that may be transferred to the water bodies. Furthermore, there is the striking geogenic contribution from naturally enriched areas, presenting distinct situations that generate an increase in the concentration of chemical elements in the water bodies.

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“…The mineralization assemblage includes minerals that were formed during the different stages of hydrothermal event and are found as disseminated impregnation in the rocks and/or vein and void infillings, such as pyrite, zircon and Zr-minerals ("caldasite"), fluorite, REE phases, baryte, carbonates, molybdenum minerals and clay minerals [15]. This paper focuses on the mineralogical and technological characterization of "caldasite" due to commercial significance for Zr as refractory material.…”

Section: Introduction mentioning

confidence: 99%

“…Ref. [15] described Zr and Zr-minerals as fine-grained (< 1 mm) idiomorphic to hypidiomorphic zircons occur randomly distributed as isolated grains in the rock matrix, and with variable grain-size (0.5-5 mm) in voids, interstices and along fractures. Skeletally developed zircon is found in interstices and along grain boundaries.…”

Section: Introduction mentioning

confidence: 99%

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2014

JGRE

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In PCAC (Poços de Caldas Alkaline Complex), in southeastern Brazil, it is observed a polyphase mineralization related to Zr-, U-, Th-, Mo-, and REE-enrichment due to hydromethermal processes which affected alkaline primary rock. Primary Zr-minerals were leached and concentrated as "caldasite", a rock composed mainly by zircon and baddeleyite in different proportions. Several techniques of mineralogical characterization were applied and results indicated zircon, baddeleyite, magnetite and iron-oxyhydroxides, mainly. Magnetic separation by WHIMS (Wet High-Intensity Magnetic Separation) was performed in order to indicate the efficiency for Fe-concentration removal for potential application in refractory industry.

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Hydrothermal and supergene uranium mineralization at the Osamu Utsumi mine, Poços de Caldas, Minas Gerais, Brazil

Cited by 58 publications

References 8 publications

Sulfur isotope fractionation and sequential extraction to assess metal contamination on lake and river sediments

Sulfur isotope fractionation and sequential extraction to assess metal contamination on lake and river sediments

Distribution of major and trace elements in bottom sediments of the Taquari River Basin, Caldas municipality (Brazil)

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