Acid mine drainage formation and arsenic mobility under strongly acidic conditions: Importance of soluble phases, iron oxyhydroxides/oxides and nature of oxidation layer on pyrite

Carlito Baltazar Tabelin; Ryan D Corpuz; Toshifumi Igarashi; Mylah Villacorte-Tabelin; Richard Diaz Alorro; Kyoungkeun Yoo; Simit Raval; Mayumi Ito; Naoki Hiroyoshi

doi:10.1016/j.jhazmat.2020.122844

Acid mine drainage formation and arsenic mobility under strongly acidic conditions: Importance of soluble phases, iron oxyhydroxides/oxides and nature of oxidation layer on pyrite

J Hazard Mater. 2020 Nov 15:399:122844. doi: 10.1016/j.jhazmat.2020.122844. Epub 2020 May 20.

Authors

Carlito Baltazar Tabelin¹, Ryan D Corpuz², Toshifumi Igarashi³, Mylah Villacorte-Tabelin⁴, Richard Diaz Alorro⁵, Kyoungkeun Yoo⁶, Simit Raval⁷, Mayumi Ito³, Naoki Hiroyoshi³

Affiliations

¹ School of Minerals and Energy Resources Engineering, The University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: c.tabelin@unsw.edu.au.
² Nanolabs LRC Co. Ltd., Quezon City 1105, Philippines.
³ Division of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan.
⁴ Department of Biological Sciences, College of Science and Mathematics, Mindanao State University-Iligan Institute of Technology, Iligan City 9200, Philippines.
⁵ Western Australian School of Mines: Minerals, Energy and Chemical Engineering, Curtin University, Kalgoorlie, WA 6430, Australia.
⁶ Department of Energy and Resources Engineering, Korea Maritime and Ocean University, Busan 49112, South Korea.
⁷ School of Minerals and Energy Resources Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.

PMID: 32534389
DOI: 10.1016/j.jhazmat.2020.122844

Abstract

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, FeSO₄·7H₂O) 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' coating 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.

Keywords: Acid mine drainage; Arsenic; Pyrite oxidation; Scorodite; Secondary minerals.

Publication types

Research Support, Non-U.S. Gov't