Abstract

Scorodite precipitation is widely employed for the fixation of arsenic in hydrometallurgical industries. However, its stability in reducing environment is not yet fully understood. This work investigated the effect of hydroquinone-induced Fe(III) reduction on the stability of scorodite. The results showed that <= 3% (11.3 mg L-1) arsenic and <4% (11 mg L-1) Fe(II) were released into solution after 72-90% of Fe(III) was reduced to Fe(II) at pH 4-8. This indicated that most of the reductive decomposition generated Fe(II) and As(V) were retained in the solid phases as secondary minerals. The XRD, ATR-FlIR, Raman, SEM-EDS and chemical analysis suggested that amorphous FeHAsO4.xH(2)O was very likely the major sink for arsenic immobilization. At pH 9, the scorodite decomposed completely resulting in similar to 19% (71.2 mg L-1) arsenic and similar to 3% (8.2 mg L-1) Fe(II) release and a residual solid of Fe/As similar to 1.2. Both amorphous ferrous arsenates and Fe(II, III) (hydr)oxides were probably responsible for the retention of arsenic in this case. The solubility of scorodite in terms of dissolved arsenic concentration upon iron reduction at pH 7-9 was significantly lower than that in oxic environment under the conditions of this work. (C) 2016 Elsevier B.V. All rights reserved.

Keywords

Scorodite; Arsenic; Mobilization; Iron reduction

Published in

Hydrometallurgy
2016, Volume: 164, pages: 228-237
Publisher: ELSEVIER SCIENCE BV

UKÄ Subject classification

Metallurgy and Metallic Materials


Publication identifier

DOI: https://doi.org/10.1016/j.hydromet.2016.06.001

Permanent link to this page (URI)

https://res.slu.se/id/publ/85380