109mn0504acidminedrainage-130711004937-phpapp01
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Sources o, Acid Mine Drainage
( Mining o, gold/ sil+er/ co--er/ iron/ inc/
lead %or combined metals&/ and coal
During e2-loration/ o-eration/ and closure o,
mine/ ,rom the mine3s:
( de*atering system
( tailings dis-osal
( *aste hea-s
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4rocess o, Acid Mine Drainage
( eochemical and microbial reactions during
*eathering o, sul,ide minerals %-yrite& in
coal/ re,use/ or mine o+erburden62idation o, sul,ide minerals in the -resence o,
air/ *ater/ and bacteria
7ormation o, sul,uric acid and increase inacidity
Solubiliation o, metals due to lo* -)
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!,,ects o, Acid Mine Drainage
( $ater resources
Increased acidity
De-leted o2ygen
Increased *eathering o, mineralsrelease o,
hea+y metals8to2ic elements into stream
4reci-itation o, 7e%6)&9bright orange coloro, *ater and roc.s
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!,,ects o, AMD %cont3d&
( Biological resources
o* -) and o2ygen content*ater
unsuitable ,or a;uatic li,e
4reci-itation o, 7e%6)&9( Increased turbidity and decreased -hotosynthesis
( Clogging o, interstitial -ore s-ace in coars a;uatic
substrate habitat
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!,,ects o, AMD %cont3d&
( Biological resources
!limination o, a;uatic -lantschange in
channel hydraulics
Stress on other biota associated *ith a;uatic
habitats
( )uman resources
Corrosion o, -i-es/ -um-s/ bridges/ etc#
Degradation o, drin.ing *ater su--lies
)arm to ,isheries
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Chemistry o, Acid Mine Drainage
?6=> =)=67e =>> S6> )>
( *eathering o, -yrite in the -resence o, o2ygen and *ater to-roduce iron%II&/ sul,ate/ and hydrogen ions
> ?6=> =)=67e9>
> =)=6( o2idation o, 7e%II& to 7e%III&
( rate determining ste-
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Chemistry o, AMD %cont3d&
> 1=)=67e%6)&9> 1=)>
( hydrolysis o, 7e%III&
( -reci-itation o, iron%III& hydro2ide i, -) @ #5
17e>> )=6157e=>> =S6=B> 1)>
( o2idation o, additional -yrite %,rom ste-s 1 and =& by 7e%III&
here ironis the o2idiing agent/ not oxygen
( cyclic and sel,-ro-agating ste-
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Chemistry o, AMD %cont3d&
6+erall 156=> 1)=67e%6)&9> )=S6
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reatment
( Chemical reatment
1# Calcium 62ide
=# Anhydrous Ammonia
( 4assi+e reatment
1# $etlands =# 6-en imestone channel
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Calcium 62ide
( Its Al.aline in nature
( Addition o, calcium o2ide increase the 4)
le+el o, AMD#
( Cause many o, the metals -resent in solution
to -reci-itate as hydro2ides and carbonates#
( It has the lo*est material cost and is the
sa,est and easiest to handle#
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Anhydrous Ammonia
( In the gaseous state/ ammonia is e2tremely
soluble and reacts ra-idly#
(It beha+es as a strong base and can easilyraise the -) o, recei+ing *ater#
( InEection o, ammonia into AMD is one o, the
;uic.est *ays to raise *ater -)#
( It should be inEected into ,lo*ing *ater at the
entrance o, the -ond to ensure good mi2ing
because ammonia is lighter than *ater#
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$etlands
( $etlands ha+e se+eral ,unctions that aid in
the remo+al o, metals in drainage
(It acts on ,iltering mechanism o, the dense-lant root system *hich catches any o, the
sus-ended solid and ,locculated -articles as
they -ass through the *etland#
( here are t*o ty-es o, *etland *hich are
used: 1# Aerobic *etlands =# Anaerobic
*etlands
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( Aerobic *etlands are shallo* %1 to ,oot
dee-& -ondsF they ,illed *ith soil or organic
matter# hey ,acilitate natural o2idation o,the metals and -reci-itate iron/ manganese/
and other metals#
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( Anaerobic *etlands are shallo* -onds
,illed *ith organic matter/ such as com-ost/
and underlain by limestone gra+el# It usedto neutralie acidity and reduce metals to
the sul,ide ,orm#
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6-en imestone Channel
( Its an o-en/ ,ree,lo*ing channel lined *ith
coarse limestone#
( hese systems o2idie and -reci-itate
metals and add al.alinity to the *ater#
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The best method to treatThe best method to treat
AMD is preventionAMD is prevention
his can be done by
using -ro-er
reclamationmethods/ *hich
-re+ents air and8or
*ater ,romreaching the -yritic
materials#
< ,
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THANK !"
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