Environmental Engineering Reference
In-Depth Information
(ANC).. The. resulting. self-neutralizing. characteristic. provides. opportunity.
for.environmentally.sound.surface.storage.without.encapsulation.
Tailings
Stawell.Gold.Mine,.230.km.northwest.of.Melbourne.(Figure.20.1),.is.deposit-
ing. tailings. into. a. TSF. (Tailings. Dam. No.. 2). of.∼100.ha. which,. at. the. time.
of. mine. closure,. will. contain. a. minimum. of. 10. million. tons. of. tailings.
with.sulide.content.of.around.2-6.wt%..The.predominant.sulide.is.pyrite,.
although.there.are.lesser.amounts.of.pyrrhotite,.arsenopyrite,.and.sphalerite..
Characteristically. of. the. Victorian. Goldields,. the. tailings. contain. signii-
cant.quantities.of.arsenic,.present.in.solid.solution.in.pyrite.as.well.as.in.the.
arsenopyrite..Acid/base.accounting.of.tailings.deposited.during.the.period.
of. this. study. shows. them. to. be. “non-acid. producing”. or. occasionally. very.
weakly.acid-producing..Net.Acid.Producing.Potential.(NAPP).of.48.samples.
from.the.main.experimental.facility.Tailings.Experimental.Research.Facility.
(TERF). had. an. average. maximum. potential. acidity. of. 106.23.kg. H 2 SO 4 /
ton. and. an. acid. neutralizing. capacity. (ANC). of. 147.82.kg. H 2 SO 4 /ton,. i.e.,.
NAPP.=.−41.58.kg.H 2 SO 4 /ton..The.inherent.ability.of.the.tailings.to.neutralize.
acid.solutions.produced.by.sulide.oxidation.is.readily.observed.within.exca-
vations. made. into. two. older. TSFs,. which. show. a. sharply. fronted. oxidized.
0
50 km
Warracknabeal
Victoria
Horsham
Bendigo
Stawell
Goldfields
Grampians
national
park
Ballara t
Melboume
0
100 km
FIGURE 20.1
Location.of.Stawell.Gold.Mine.in.the.Victorian.Goldields.
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