外文翻译了解矿区水和盐的动态 支持集成水质和质量管理.docx

外文翻译了解矿区水和盐的动态 支持集成水质和质量管理.docx

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外文翻译了解矿区水和盐的动态支持集成水质和质量管理

中文3600字

本科毕业设计（论文）

外文翻译

原文：

Understandingminesitewaterandsaltdynamicstosupportintegratedwaterqualityandquantitymanagement

Waterreuseisbecominganintegralcomponentofthewatermanagementstrategyonminesites.Thispractiseisbeingdrivenbycorporatesustainabilitygoals,communityandsocietalpressurestodemonstrateimprovedwaterstewardship,aswellasclimateandregulatorypressures.However,waterreuseoftenresultsinwaterqualitycompromisewhichcanthenresultindecreasedrecoverythroughproblemsinprocessingcircuits,productquality,andanincreasedlikelihoodofdischargeofwaterthatcannotmeetenvironmentalregulatoryrequirements.Onmostminesites,thereisusuallyadisjuncturebetweenwaterquantitymanagementandwaterqualitymanagementwiththelatterbeingmanagedsolelyasanenvironmentalproblem.Itisbecomingincreasinglyclearthatwaterqualityandquantitymustbemanagedasanintegratedsystem.Inordertointegratewaterqualityandquantitymanagementtoachievemultipleobjectivesthedynamicsofwaterandconstituentsmustbeunderstood.UsingexamplesfromastudybeingconductedatacoalminetheBowenBasin,thispaperwilloutlinethedynamicsofwaterandsaltsonthesite.

Introduction

Theneedforsustainablewatermanagementpractisesisbeingdrivenbycorporatesustainabilitygoals,increasedpublicscrutinyofwateruse,management,andenvironmentalstewardship,therelativeeconomicsofincreasingreuseagainstthealternativeofincreasedsupplyoffreshwaterandclimateconditions.Theabilitytosimultaneouslymeetwaterquantity,waterqualityandproductqualityobjectivesisbecominganincreasinglychallengingcomponentofwatermanagementonminesites.However,becausethewatersystemonaminesiteactsasacomplexsystemwithfeedbacksandinteractionsbetweenthenaturalclimatedrivensystemandtheengineeredreticulationthereareoftenunintendedimpactsfromwatermanagementdecisionsthatonlyconsideronesetofobjectives

Inthecoalindustry,therehasbeenconsiderableinvestmentinimprovingwatermanagementonsites.Thishasbeendrivenbywidespreadandprolongeddroughtaswellascorporatetargetsforfreshwatersavings.Overthelastdecademostsiteshaveadoptedwaterreuseasameansformakingfreshwatersavings.However,waterreuseresultsinincreasedsalinityinsitewaterstores（Moranetal,2006）.Theincreaseinsalinityisdrivenlargelybyevaporationandongoingsaltinputsfromspoil,coalandgroundwater.Effectivemanagementofdissolvedsaltscanprovideopportunitiesforreducingrisksandcostsinmanagingwaterandtheenvironment,processingefficiency,productqualityandoperating/maintenance.

Inordertomanagebothwaterqualityandquantityinanintegratedsystemtomeetmultipleobjectivesoncoalminesrequiresanunderstandingofthenatureandsourcesofsalts;thedynamicsofthesaltfluxesonasite;andtheimpactofwaterqualityonproductionandproductquality.Thesefactorsmustalsobebalancedagainsttheriskofnon-compliantdischarge.Theaimofthisworkwastoincreaseunderstandingofthemineandclimateconditionsthatresultinsaltfluxesfromvariouspartsofthesiteintotheminewaterreticulationsystem.Withthisinformation,operationalguidelinescanbedevelopedthatallowsitestoproactively,ratherthanreactivelymanagethewatersystemtomeetmultipleobjectives.

Thispaperwillpresentdatathatillustratetheresponsesofrepresentativewaterbodiesonthesitestochangingclimaticconditions.Previousmodellingofwaterandsaltfluxeshasassumedthatsaltsbehaveconservatively,iethatsaltconcentrationofawaterbodywillonlychangeindirectproportiontothemixingofinputwaterswithdifferentsaltconcentrations（egMoranetal,2006）.Whilethisisagenerallyacceptableassumptionforpredictingtotalsaltconcentrationsandtheoverallimplicationsofwatermanagementstrategies,manyindividualionscomprisingthesaltloadmayparticipateinbiogeochemicalreactionswhichmaydramaticallyaltertheioncompositionofawaterbody.Thisalteredioncompositionmayhaveimpactsonparticularprocesses.Forexample,itisknownthatdivalentcations（MgandCa）providegreaterflotationbenefitsduringcoalwashingthanmonovalentcations（Oforietal,2005）.Thusitisimportanttonotonlyunderstandthedynamicsoftotalsaltsonasitebutalsotheprincipalprocessesgoverningtheconcentrationsofindividualionscomprisingthesalts.

Oneofthedifficultiesinunderstandingthedynamicsofwaterandsaltsonminesitesisthatitisdifficulttodistinguishbetweenwaterfromdifferentsourcesandthereforeaccuratelyattributesaltfluxes.Inputsfromanumberofwatersources,eggroundwater,run-off,etccannotbemetered.InthisworkstableisotopesOxygen-18（denotedd18O）andDeuterium（denoteddD）havebeenusedinconjunctionwithgeochemicalsignaturestotraceinputsfromtheseunmeteredwatersources

6Timesseriesofcation（top）andanion（bottom）concentrationchangesdeterminedinsurfacewatersofPitF.Average（z1sd）.Deepwaterconcentrationsareshownforcomparison

7Cation（top）andAnion（bottom）compositionofrun-offfromspoilandroad

Run-offcomposition

Althoughrun-offfromspoilisnotalargeinputtoPitFduetothesmallcatchmentarea,thecontributionviathisprocessappearstoimpactthesurfacewaterioncompositionasdiscussedbelow.Thisprocessmayhaveamorepronouncedimpactonthewaterqualityofwaterstoreswithlargercatchmentareasorareaswithhighlyactivespoil.ChangestorainfallcompositionduringrunofffromspoilandroadsisshowninFigure7andtotalconcentrationsasaproportionoftotalionsinFigure8.RainfallcompositionistakenfromBrasellandGilmour（1980）andProbert（1976）.Basedonthemethodofcollectionandsimilaritybetweenthed18OandDdcompositionoftherun-offsamplesandrainfall（Figure9）,therun-offsamplescollectedinthisstudyarelikelytomostlyreflectcompositionofsurfaceorfastflowpathrun-offratherthanrun-offfromrainfallthathasinfiltratedthespoilbeforeflowingtothepit.Fastflowpathrun-offmayalsoincludeinfiltrationthroughcracksorfracturesinthespoil.Thustheioncompositionofthesesamplesmaydiffersignificantlyfromthetotalrun-off（surfacezinfiltration）enteringthepitduringeventsduetotheshortercontacttimeoftherainwaterwithspoil.Ongoingworkisbeingconductedtoelucidatetherelativeimportanceofsurfaceanddeeperflowpathsthroughspoilandconsequentioninputsdeliveredtothepitsunderdifferentconditions.

WhatisapparentfromFigures7and8isthatthereisconsiderablevariabilityinboththeamountofsaltsdeliveredviarun-offandtherelativeproportionofionsinsolution.ComparisonoftheratioofCa,MgrelativetoNaandCl:

SO4betweenPitFrun-offandraincompositionisconsistentwiththeobservedchangesinsurfacewatercompositionshowninFigure6.Variabilitybetweenthespoilrun-offsamplesislikelytoreflectspatialvariabilityinthespoilpropertiesacrossthesite.Further,Gozzard

8Relativeproporationofcations（top）andanions（bottom）determinedinrun-offfromspoilandhaulroads

etal（thisvolume）suggestedthatbothsaltdissolutionandcationexchangewithclaysmaybeimportantmechanismsbywhichthecationcompositionchangesduringrun-offfrospoil.ComparisonofaveragepitwatercompositionforPitFandQswithrun-offcompositionandsequentiallyextractedsaltandexchangeablefractionsfrmomspoilsamples（Figure10）suggeststhatthemechanismbywhichcationsaremobilisedtosolutionarealsospatiallyvariable.ThedynamicsofcationcompositioninPitQsandassociatedrun-off,forexample,appearstobedominatedbysaltdissolution.Incontrastthecationcompositionofbothrun-offandthesaltfractionforPitFarefarmorevariable（Figure10b）.ComparisonofrunoffandthesequentialextractiondatawiththePitFcompositionsuggeststhatwhilesaltdissolutionislikelytobeanimportantinputmechanism,cationexchangemayalsoplayasignificantroleindeterminingthecompositionofrun-offfromrehabilitatedareastothepit.

Providingconsistentwaterqualityforcoalwashing

Inmostcasessitescanadaptprocessestoaccommodatedifferentwaterquality.Forexample,mostcoalminesintheBowenBasinhaveshiftedfromusingfreshwatertosaltywaterforcoalwashing.Inthisinstanceswitchingtosaltywaterprovidedbenefitsbyimprovingflotationwithreducedreagentuse（Oforietal,2005）.However,insituationswherewaterqualitychangesonrelativelyshorttimescalessuchasshowninFigure4,adaptationisnotusuallypossiblebecauseinmostcasessitesdonothavesufficientinformationortoolstopredictchangesinwaterquality.OftenitisassumedintheCHPPthatchangesinROMcoalpropertiesarethesourceofvariationinflotationperformance.Propertiesofthefeedcoalaremonitoredwhereaswaterqualityparametersarenottypicallymonitored.Figure11showschangesinflotationreagentuseduringthewetseasonof2007/2008.Itcanbeseenthatbothfrotherandcollectorusagewasincreasedasflotationyieldsdecreasedduetothelowerconductivityofthefeedwater.Duringthisperiodwhilethereweresomechangesinfeedcoalproperties,theprimaryfactoraffectingflotationwasthechangestowaterquality.Duringtheserainfalleventstheoperatorswerenotawareoftheconductivitychangesinthefeedwaterandsowererespondingreactivelyratherthanproactivelytomaintainproduction.

AtGermanCreekprovidingrelativelyconsistentwaterqualityforcoalwashing,evendur