Assessment of alkaline cover performance for abatement of ARD from waste rock dumps at Savage River Mine
Date
2011
Authors
Li, J.
Kawashima, N.
Schumann, R.C.
Hughes, A.
Hutchison, B.
Kent, S.
Kaplun, K.
Ciccarelli, J.M.
Smart, R.S.C.
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Conference paper
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Proceedings of the Seventh Australian Workship on Acid and Metalliferous Drainage, 2011, pp.241-253
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7th Australian Workship on Acid and Metalliferous Drainage (AMD) Emerging Trends in Acid and Metalliferous (21 Jun 2011 : Darwin, Australia)
Abstract
B-dump is one of the legacy (sulphide containing) waste rock dumps at the Savage River iron ore mine, Tasmania. This historic dump has been identified as a significant source of acid rock drainage (ARD) that has caused environmental harm to Main Creek and Savage River. In 2006, combined water shedding and alkaline (calcite-chlorite schist) covers were constructed over the dump to reduce the acid load from this dump for long-term ARD control. On the basis of our previous research, it was expected that the alkaline covers would allow rainfall infiltration to take up alkalinity and dissolved silicate as water seeps through the cover material neutralising existing ARD, and producing a stable coating of secondary products at the sulphide grain surfaces reducing their acid generation rate.
As part of the AMIRA International-funded project "Alternative Treatment Options for Longterm ARD Control" (P933A), a survey of the B-dump calcite-chlorite schist (CCS) side cover was carried out. Excavation sampling of the CCS side cover was undertaken after the cover had been in place for about four years. This paper focuses on the results from our investigations of water samples taken from Bdump seeps and solid samples taken from different layers of the cover and original ARD rock within the dump. A mineralogical survey, geochemical characterisation and surface analysis of pyrite in each of the layers were undertaken. There appears to be strong evidence from this study that the ratio of acid generation and neutralisation rates within the dump is proceeding towards unity, and that passivation of pyrite particles is occurring at the interface of the CCS cover and the acid forming materials.
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Copyright 2011 JKTech