Transpassive oxidation of pyrite

Journal Article · Thu Jul 01 04:00:00 EDT 1993 · Journal of the Electrochemical Society; (United States)

DOI:https://doi.org/10.1149/1.2220741· OSTI ID:6384473

Zhu, Ximeng; Bodily, D M; Wadsworth, M E ^[1]

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1. Univ. of Utah, Salt Lake City (United States). College of Mines and Earth Sciences

The electrochemical behavior of mineral and coal pyrites in basic borate/sulfate solutions was investigated using cyclic voltammetry with both stationary and rotating disk electrode. Emphasis was centered on transpassive oxidation. In the transpassive region, 0.4 to 0.8 V (SCE), aggressive oxidation of pyrite occurred. The reaction products in this region are Fe(III) oxides, sulfate ion, and partially oxidized sulfur intermediates. The formation of sulfur and polysulfides was identified by in situ Raman spectroscopy. Exposure of pyrite to anodic potentials higher than the transpassive region resulted in rapid oxidation of sulfur intermediates to sulfate ion. The effect of electrode rotation speed, electrode precondition time, and upper potential of the scan in the transpassive region was observed to be critical to the formation of sulfur intermediates. Sulfur intermediates, formed in the transpassive region, dramatically affected subsequent oxidation reactions occurring in the lower potential region. The magnitude of two dominant oxidation peaks, a ferrous hydroxide peak and an iron sulfide peak, observed in this region correlated directly with the quantity of sulfur intermediates formed in the transpassive region. This effect was less pronounced for coal pyrites compared to mineral pyrite.

• DOE Contract Number: AC22-89PC89758
• OSTI ID: 6384473
• Journal Information: Journal of the Electrochemical Society; (United States), Journal Name: Journal of the Electrochemical Society; (United States) Vol. 140:7; ISSN JESOAN; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010402* -- Coal
Lignite
& Peat-- Purification & Upgrading
BORATES
BORON COMPOUNDS
CARBONACEOUS MATERIALS
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
COAL
DESULFURIZATION
ELECTROCHEMISTRY
ELEMENTS
ENERGY SOURCES
FOSSIL FUELS
FUELS
HYDROGEN COMPOUNDS
HYDROXIDES
IRON COMPOUNDS
IRON HYDROXIDES
IRON OXIDES
IRON SULFIDES
LASER SPECTROSCOPY
MATERIALS
MINERALS
NONMETALS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PYRITE
RAMAN SPECTROSCOPY
REACTION INTERMEDIATES
SPECTROSCOPY
SULFATES
SULFIDE MINERALS
SULFIDES
SULFUR
SULFUR COMPOUNDS
SULFUR OXIDES
TRANSITION ELEMENT COMPOUNDS
VOLTAMETRY