DOC

(DOC) Evolution

By Lawrence Gibson,2014-07-22 02:57
9 views 0
Evolution

    Evolution

30CHINESEJ0URNAL0FGE0CHEMISTRVo1.25(Supp1.)2006

    ;ofcyanidetreated.arsenopyriteconcentratewerestoredinawasterockimpoundment.whichwasleftopenuntil2000whenitwas

    ;cappedwithlayersofwasterock.clayandsilttominimizewaterinfiltrationandtheoxidativereleaseofarsenic.Anotherpotential

    ;sourceis

    eemergencydischargeareaforNorAcmetailings.throughwhichMWl7isdrilled.Coresampleswereobtainedfromthe

    ;ARS.thetailingsareaandotherregionsoftheminesite.Themineralogywasdeterminedbyopticalandscanningelectron

    ;microscopy,andX.raydiffraction.Ground.surfaceandsqueezedporewaterwasanalyzedandthegeochemistrywasmodeledusing

    ;W_ATEO4fandGeochemistsWorkbench.ThehydrologyofthesitewasmodeledusingGeostudioSEEPWusingvaluesofhydraulic

    ;conductivitymeasuredinsitu.TheconcentrationsofarsenicinothermonitoringwellsinthevicinityoftheARSandtheNorAcme

    ;tailingsare<0.1×10....andintheporewaterofthetailings<5×l0....whichindicatesthatthetailingsareunlikelytobethesourceof

    ;thecontamination.Higherconcentrations(<9×10)werefoundinsurfacew

ateronthetailingsandinaswampyarea(<l4×10..)tl1at

    ;containedthesurficialrunofffromtheARSpriortocapping.PorewaterintheunoxidizedzoneoftheARScontains<lO0mg/Ltotal

    ;arsenic

    <25mg/LAs(m)]possiblyremobilizedfromsecondaryphases,amorphousironsulfoarsenates,scoroditeandjarosite

    ;formedpriortocappingbyoxidationofprimarysulfideminerals.HydrologicalmodelingsuggeststhatAsistransportedintothe

    ;aquiferbelowtheARSbyadvectionanddiflusion.AttenuationofAsinsurfacewatersappearstobeadsorptionofAs(V)onFe(III)

    ;oxyhy&oxidessuchasferrihydrite.althoughintheaquiferthemajorityoftheAsisthemoresolubleAs(HI).

    ;Keywordsarsenic;arsenopyriteresidue;watercontamination;mobility;attenuation

    ;EvolutionofminepoolchemistryattheSydneyCoalfield,NovaScotia,Canada,andits

    ;implicationsforminedecommissioning

    ;Y.T.JohnKwong,SteveForgeron,RobertJ.MacDonald

    ;CANMETMiningandMineralSciencesLaboratories,Ottawa,Canada ;Conestoga-Rovers&AssociatesLtd..Sydney,Canada

    ;CapeBretonDevelopmeritCorporation,Sydney,Canada

    ;TheSvdneyCoalfieldisthelargestinAtlanticCanadainwhichaboutl00coal

mineswithvariedlifespanhavebeenopenedsince

    ;1720.IntheGlaceBaysub.basin.coalseamssubcropclosetotheAtlanticcoastanddipseaward.Coalhasbeenminedat>l200m

    ;depthandllkmfromthecoastline.Depositedpossiblyunderamarineinfluence.thecoalsareenrichedinpyrite.Duringmining

    ;abundantacidicsulfatessuchasmelanterite.rozenite.copiapiteandhalotrichitehaveaccumulatedintheundergroundworkingsdue

    ;topyriteoxidation.Thedissolutionoftheseefflorescentsaltsuponminefloodingatclosuregivesrisetoacidicminepoolswherever

    ;insufficientacidneutralizingmaterialsarepresent.Amajorchallengeofminedecommissioningintheareaistopreventthe

    ;dischargeofthisacidicwaterintotheopenocean.Watermonitoringinthe1BHydraulicSystem.whichconsistsoftenmines

    ;connectedatvariousdepthsbynaturalormanmadeconduits,showsthatthe

    minepoolchemistryvarieswiththeminingpractice

    ;employed.Althoughcoalhasinvariablybeenminedbytheroomandpillarmethod.theextentofpillarremovalvariesfrommineto

    ;mine.Inmineswithminimalpillarremova1.coalextractioncouldbeaslowas45%.leavingmuchpyriteforoxidationpriorto

    ;eventualfloodingandanacidicminepoolOCCurS.Incontrast,inmineswithextensivepillarremoval,coalextractioncouldamountto

    ;85%.1eavingmuchlesspyriteforoxidation.Moreover,theextensivepillarre

movalcausedthecollapseoftheoverlyingstratawhich

    ;insomeareasincludelimestone.Theinfillingofmineworkingswithcarbonaterichmaterialoffsetstheeffectsofacidicemorescent

    ;saltsandaminepoolwithnearneutralpHresults.Geochemicalmodelingha

    saffirmedthecontroloflocalwaterchemistrybythe

    ;prevalentmineralassemblage.Takingadvantageofthehydraulicconnectionamongminepoolsinthe1BHydraulicSystemandthe

    ;localvariationinwaterchemistry,thedischargeofacidicwaterfromamajoroutfaUhasbeenarrestedbyartificiallywithdrawing

    ;cleanwaterfromanadjacentminepoo1.Thelongevityofsuchatemporaryactiondependsonwhethercontinualwaterwithdrawal

    ;willeventuallyupsetthechemicalequilibriumestablishedinthesystem.Longtermdecommissioningstrategyiscurrentlyunder

    ;development.

    ;Keywordscoalmining;geochemistry;acidminedrainage;environmentalimpact;decommissioningstrategy

    ;Heavymetaldistributionandevolutioninacidminedrainagesystemdevelopedfromnickel

    ;sulfidetailings(WesternAustralia)

    ;LiangqiLEI

    ;

    ;

Report this document

For any questions or suggestions please email
cust-service@docsford.com