TY - JOUR
T1 - Formation of aluminum hydroxide-doped surface passivating layers on pyrite for acid rock drainage control
AU - Zhou, Yan
AU - Fan, Rong
AU - Short, Michael
AU - Li, Jun
AU - Schumann, Russell
AU - Xu, Haolan
AU - Smart, Roger
AU - Gerson, Andrea
AU - Qian, Gujie
PY - 2018/9/19
Y1 - 2018/9/19
N2 -
The aim of this study was to test the performance of a novel method for acid rock drainage (ARD) control through the formation of Al(OH)
3
-doped passivating surface layers on pyrite. At pH 2.0 and 4.0, there was no obvious inhibition of the pyrite oxidation rate on addition of 20 mg L
-1
Al
3+
(added as AlCl
3
·6H
2
O). In comparison, the pyrite oxidation rate at circumneutral pH (7.4 ± 0.4) decreased with increasing added Al
3+
with ≈98% reduction in long-term (282 days) dissolution rates in the presence of 20 mg L
-1
Al
3+
. Al
3+
was added to the solution and allowed to equilibrate prior to pyrite addition (2 g L
-1
). Consequently almost all Al
3+
(>99.9%) was initially present as aluminum hydroxide precipitates at pH 7.4. X-ray photoelectron spectroscopy analysis showed a significant concentration of Al
3+
(20.3 at. %) on the pyrite surface reacted at pH 7.4 with 20 mg L
-1
added Al
3+
, but no Al
3+
on pyrite surfaces reacted at pH 2.0 and 4.0 with added Al
3+
. Transmission electron microscopy and synchrotron X-ray absorption near edge spectroscopy analyses indicated that compact surface layers containing both goethite and amorphous or nanocrystalline Al(OH)
3
formed in the presence of 20 mg L
-1
Al
3+
at circumneutral pH, in contrast to the porous goethite surface layers formed on pyrite dissolved in the absence of Al
3+
under otherwise identical conditions. This work demonstrates the potential for novel Al-based pyrite passivation of relevance to the mining industry where suitable Al-rich waste materials are available for ARD control interventions.
AB -
The aim of this study was to test the performance of a novel method for acid rock drainage (ARD) control through the formation of Al(OH)
3
-doped passivating surface layers on pyrite. At pH 2.0 and 4.0, there was no obvious inhibition of the pyrite oxidation rate on addition of 20 mg L
-1
Al
3+
(added as AlCl
3
·6H
2
O). In comparison, the pyrite oxidation rate at circumneutral pH (7.4 ± 0.4) decreased with increasing added Al
3+
with ≈98% reduction in long-term (282 days) dissolution rates in the presence of 20 mg L
-1
Al
3+
. Al
3+
was added to the solution and allowed to equilibrate prior to pyrite addition (2 g L
-1
). Consequently almost all Al
3+
(>99.9%) was initially present as aluminum hydroxide precipitates at pH 7.4. X-ray photoelectron spectroscopy analysis showed a significant concentration of Al
3+
(20.3 at. %) on the pyrite surface reacted at pH 7.4 with 20 mg L
-1
added Al
3+
, but no Al
3+
on pyrite surfaces reacted at pH 2.0 and 4.0 with added Al
3+
. Transmission electron microscopy and synchrotron X-ray absorption near edge spectroscopy analyses indicated that compact surface layers containing both goethite and amorphous or nanocrystalline Al(OH)
3
formed in the presence of 20 mg L
-1
Al
3+
at circumneutral pH, in contrast to the porous goethite surface layers formed on pyrite dissolved in the absence of Al
3+
under otherwise identical conditions. This work demonstrates the potential for novel Al-based pyrite passivation of relevance to the mining industry where suitable Al-rich waste materials are available for ARD control interventions.
UR - http://purl.org/au-research/grants/ARC/LP140100399
UR - http://purl.org/au-research/grants/ARC/LP130100568
UR - http://www.scopus.com/inward/record.url?scp=85054690406&partnerID=8YFLogxK
U2 - 10.1021/acs.est.8b04306
DO - 10.1021/acs.est.8b04306
M3 - Article
VL - 52
SP - 11786
EP - 11795
JO - Environmental Science and Technology
JF - Environmental Science and Technology
SN - 0013-936X
IS - 20
ER -