Journal
JOURNAL OF HAZARDOUS MATERIALS
Volume 399, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.jhazmat.2020.122844
Keywords
Acid mine drainage; Arsenic; Secondary minerals; Scorodite; Pyrite oxidation
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Funding
- Japan Society for the Promotion of Science (JSPS) [JP17K12831, JP26820390]
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Acid mine drainage (AMD) formation and toxic arsenic (As) pollution are serious environmental problems encountered worldwide. In this study, we investigated the crucial roles played by common secondary mineral phases formed during the natural weathering of pyrite-bearing wastes soluble salts (melanterite, FeSO4 center dot 7H(2)0) and metal oxides (hematite, Fe2O3)-on AMD formation and As mobility under acidic conditions (pH 1.5-4) prevalent in historic tailings storage facilities, pyrite-bearing rock dumps and AMD-contaminated soils and sediments. Our results using a pyrite-rich natural geological material containing arsenopyrite (FeAsS) showed that melanterite and hematite both directly-by supplying H+ and/or oxidants (Fe3+)-and indirectly-via changes in the nature of oxidation layer formed on pyrite-influenced pyrite oxidation dynamics. Based on SEM-EDS, DRIFT spectroscopy and XPS results, the oxidation layer on pyrite was mainly composed of ferric arsenate and K-Jarosite when melanterite was abundant with/without hematite but changed to Fe-oxyhydroxide/oxide and scorodite when melanterite was low and hematite was present This study also observed the formation of a mechanically 'strong' coaling on pyrite that suppressed the mineral's oxidation. Finally, As mobility under acidic conditions was limited by its precipitation as ferric arsenate, scorodite, or a Fe/Al arsenate phase, including its strong adsorption to Fe-oxyhydroxides/oxides.
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