109mn0504acidminedrainage-130711004937-phpapp01

7/24/2019 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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