نتایج جستجو برای: pyrolusite

تعداد نتایج: 90  

2017
James K. Fredrickson John M. Zachara David Kennedy Chongxuan Liu Martine Duff Douglas Hunter Alice Dohnalkova JAMES K. FREDRICKSON JOHN M. ZACHARA DAVID W. KENNEDY CHONGXUAN LIU MARTINE C. DUFF DOUGLAS B. HUNTER ALICE DOHNALKOVA

The potential for Mn oxides to modify the biogeochemical behavior of U during reduction by the subsurface bacterium Shewanella putrefaciens strain CN32 was investigated using synthetic Mn(III/IV) oxides (pyrolusite [ -MnO2], bixbyite [Mn2O3] and K -birnessite [K4Mn14O27 8H2O]). In the absence of bacteria, pyrolusite and bixbyite oxidized biogenic uraninite (UO2[s]) to soluble U(VI) species, wit...

Journal: :Chemical Engineering and Processing 2021

The recovery mechanism of manganese from low-grade pyrolusite was studied through microwave and conventional leaching, respectively, pyrite used as the reducing agent. An improvement on leaching rate with heating noticed which may be caused by suppressing formation sulfur passivation layer unique dipole rotation energy. To confirm this hypothesis, time, amount agent, concentration sulfuric acid...

Journal: :Minerals 2021

The Guangxi Zhuang Autonomous Region is an important manganese ore district in Southwest China, with resource reserves accounting for 23% of the total China. Xialei deposit (Daxin County, Guangxi) first super-large discovered Mn oxide supergene oxidation zone was characterized using scanning electron microscopy (SEM), energy spectrometer (EDS), transmission (TEM, HRTEM), and X-ray diffraction a...

2002
Susan Erin O’Reilly Michael F. Hochella David F. Cox Matthew J. Eick J. Donald Rimstidt Lucian W. Zelazny

Lead sorption efficiencies (sorption per surface area) were measured for a number of natural and synthetic Mn and Fe-oxides using a flow through reactor. The Mn-oxide phases examined included synthetic birnessite, natural and synthetic cryptomelane, and natural and synthetic pyrolusite; the Fe-oxides studied were synthetic akaganeite, synthetic ferrihydrite, natural and synthetic goethite, and ...

Journal: :MATEC web of conferences 2022

Pyrolusite (β-MnO 2 ) was investigated for potential use in energy storage devices due to its promising properties cathode materials rechargeable lithium-ion batteries. A combination of evolutionary algorithm search techniques and density functional theory were used determine the structural stabilities β-MnO nanoclusters on landscape. However, pyrolusite suffers from some defects impurities tha...

ژورنال: علوم زمین 2018
Ali Asghar Calagari Behnaz Barghi, Mohammad Hossein Zarrinkoub Vartan Simmonds

Mn-bearing veins of Jonub -ESehchangi are located 200 km southwest of Birjand, Southern Khorasan province (east of Iran). These veins are hosted by andesitic rocks of Eocene to Oligocene ages. Ore minerals identified  by XRD method and mineralographic studies and are Pyrolusite, cryptomelane, psilomelane, hollandite, hematite and goethite, displaying colloform and open-space filling textures. G...

2017
Bruce S. Lieberman Richard Kurkewicz Heather Shinogle Julien Kimmig Breandán Anraoi MacGabhann

The morphology and affinities of newly discovered disc-shaped, soft-bodied fossils from the early Cambrian (Series 2: Stage 4, Dyeran) Carrara Formation are discussed. These specimens show some similarity to the Ordovician Discophyllum Hall, 1847; traditionally this taxon had been treated as a fossil porpitid. However, recently it has instead been referred to as another clade, the eldonids, whi...

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