report b integrated oil sands tailings treatment technologies march 2010.pdf
-
Upload
james-walker -
Category
Documents
-
view
15 -
download
0
Transcript of report b integrated oil sands tailings treatment technologies march 2010.pdf
-
Part B Report
A Screening Study
of
Oil Sand Tailings Technologies and Practices
Prepared for
Alberta Energy Research Institute AERI Contract 2008 0326
REVISION I. March 2010
By
David W. Devenny PhD P Eng P Geol The Rock Doctor March 2010
-
PartB:OverviewofOilSandTailings
TheRockDoctorB:ExecutiveSummaryPagei
ExecutiveSummaryPartBReport.
ThePartBReportisanoverviewofoilsandstailingspracticesandrelatedtopics.
Thereportstartswithanoverviewofregulatorymattersandthegoverningfiscalregime.Thesehaveasignificantimpactontheprojectdirection,economicsanddecisionmaking.
TheEvolutionofOilSandTailingsreviewsthehistoryoftailingspracticeandhowitresultedintodaysunfortunateinventoryofstrandedfluidtailings.Italsorecognizestheeffectofworldopiniononoilsands.FinallyitdescribesERCBDirective074thatseeksanewdirectionintailingsmanagement.
Thenextsectionprovidesastepbystepdescriptionoftailingstechnologyandpractices.Itreviewswhyfluidtailingsarecreated,containmentrequirements,dewateringrequirementsrequiredtocreatesolidtailings,andtechnologiesthatareavailabletodensifyfluidtailings.Overviewsofoilsandgeology,materialpropertiesandbehaviour,providebackgroundknowledge.
Abriefsectiononworldtailingspracticenotesthatsomeminesprefertotakeshorttermprofits,accumulatefluidtailings,anddeferreclamation.Stockpilingtailingsoftencreatesunnecessaryrisk,andmaybemoreexpensive.Deferringreclamationtransfersreclamationcoststofuturegenerations.Themainreasonforthissectionistoprofilethepoorimageofindustriesthatengageindeferralpractices.
Chapter13reviewsproceduresusedtoscreenoptionsfortailings.Traditionaleconomicanalysisofferspoorguidanceforoilsandprojects.Discounting,overthelongtimespansassociatedwithoilsandsprojects,reducesfutureobligationstoafractionoftheirrealvalue.Distortiondoesnotoccurifreclamationobligationsarebookedastheyarecreated,insteadofwhenfundsarespenttocorrectthem.Recognitioncanbeaccomplishedbydepositingfundsofequivalentvalueinanenvironmentaltrustwhentheobligationiscreated.Addedbenefitsoftheenvironmentaltrustapproachdepositsarerecognizedoperatingcosts.Thatcausesgovernmentstoshareintheexpense.Inadditiontrustdepositsoffsetanautomaticreductioninassetvalue.Finally,theapproachencouragesmanagementthatismorecompatiblewithpublicexpectations.
Informationonoilsandsprojectplans,technologies,andperformanceislimited.Greatertransparencyisneeded.
Thereviewcloseswithanoverviewofoilsandresearchpractices,andrecommendstopicsthatshouldbeexplored.
Appendicessupportthemaintext.Appendix1provideselectronicmodels.Thefirstsummarizesalllifecycleworkandtheassociatedcostdifferencesfordifferenttailingstechnologies.Thesecondoffersaneconomicmodeltoappraisethefulllifecycleofanintegratedoilsandplant.Thethirdisatailingsforecastmodel.Allmodelsallowuserstoinputtheirownvaluessotheimpactofdifferentinputcanbeobserved.Appendix4focusesonmaterialpropertiesandbehaviouranessentialpartofunderstandingtailings.
-
ReportB:OverviewofOilSandTailings
The Rock DoctorOverviewofOilSandTailingsPageii
TableofContents
# # Title PageB ExecutivesummarytoReportB i Tableofcontents ii
B.1 Introduction 1B.2 Regulatingoilsands B.2.1 Background 4 B.2.2 Albertaenvironmentalprotectionandenhancementact 4 B.2.3 ERCBmandate 4
B.3 Fiscaltermsforoilsands 5B.4 Evolutionoftailingsandreclamationpractices B.4.1 Earlyhistory 6 B.4.2 The1990s 6 B.4.3 Recentevents 8 B.4.4 500ducks 10 B.4.5 ERCBdirective074 11
B.5 OilSandsGeology B.5.1 Resourcebasemineablearea 12 B.5.2 BedrockGeology 12 B.5.3 LocalStructure 12 B.5.4 Originofthebitumen 14 B.5.6 SurficialGeology 14 B.5.7 Orebodycharacter 14
B.6 Miningoilsands 16B.7 Extraction 19B.8 BasictailingsfromextractiontoMFT B.8.1 Introductiontotailings 22 B.8.2 Theoilsandstailingscycle 22 B.8.3 Transportingtailings 24 B.8.4 Tailingssanddeposits 25 B.8.5 Behaviourinthetailingspond 27 B.8.6 Predictingthevolumeoftailings 28
B.9 TailingsDams B.9.1 Introductiontotailingsdams 30 B.9.2 Constructionwithoverburdeninsteadofsand 32 B.9.3 Constructingretentionfacilitiesinpit 33
B.10 ProcessestodensifyMFT B.10.1 Directtreatmentprocesses 34 B.10.2 BehaviourasMFTdensifies 35 B.10.3 Mechanicalprocesses 35 B.10.4 Naturalprocesses 37 B.10.5 MixturesCTandNST 38
-
ReportB:OverviewofOilSandTailings
The Rock DoctorOverviewofOilSandTailingsPageiii
# # TableofContents(continued) PageB.11 StoringMFTunderawatercap
B.11.1 Permanentstorageunderawatercap 42 B.11.2 Theendpitlake 44
B.12 Worldtailingspracticeandimage 45B.13 Screeningtechnologyoptions
B.13.1 Introduction 47 B.13.2 Characteristicsofoilsandprojects 47 B.13.3 Stepsusedtoscreentechnologyoptions 48 B.13.4 Characteristicsofeconomicanalysis 48 B.13.5 Resultsofscreeningstudies 50 B.13.6 Conclusionsonscreeningoptions 52 B.13.7 QualifyingEnvironmentalTrusts 53 B.13.8 Assigningvaluetofuturereclamationobligations 53
B.14 OilSandTailingsR&D B.14.1 IntroductiontotailingsR&D 54 B.14.2 IncentivefortailingsR&D 54 B.14.3 SuggestedprojectgoalsfortailingsR&D 55 B.14.4 CharacteristicsoftailingsR&D 55 B.14.5 Largescaletailingstechnologyresearch 58 B.14.6 Independentresearch 58 B.14.7 Anillustrationofdifficultyintegratingindependentresearch 59 B.14.8 Effectivenessofoilsandsresearchprograms 61
B.15 SummaryandConclusions V.15.1 Aboutprojectsandpractice 62 B.15.2 ERCBDirective074 62 B.15.3 Aboutmaterialproperties 62 B.15.4 Buildingtailingsdeposits 62 B.15.5 Howtolimitfluidtailings 63 B.15.6 Propertiesoffluidtailings 63 B.15.7 Directmethodsfordensifyingfluidtailings 63 B.15.8 PasteandMixedSoilCasesCTprocess 64 B.15.9 StoringMFTunderawatercap 64 B.15.10 EconomicscreeningofProjectOptions 64 B.15.11 FiscalTerms 65 B.15.12 ResearchandDevelopment 65 B.15.13 InsularCharacter 65
B.16 Closure 66
-
ReportB:OverviewofOilSandTailings
The Rock DoctorOverviewofOilSandTailingsPageiv
TableofContents(continued) Table# ListofTables PageTableB.1 Characteristicsofthreemineableoilsandprojects 2TableB.2 LanduseattheSyncrudeMildredLakeFacility 3TableB.3 AverageoreusedinthePartAStudy 15TableB.4 Forecastpropertiesoftailingssanddeposits 27TableB.5 Highlightsofinformationobtainedfromthetailingsforecastmodel 28TableB.6 Typicaldimensionsoftailingsdams 30TableB.7 HighlightsoftheJackpinesurfacetailingspond 30TableB.8 Additionalcostwhenoverburdenisusedtobuildtailingsdykes 32TableB.9 RelativevolumesintheCTprocess 39TableB.10 ConcernswiththeCTprocessingoption 41TableB.11 Traditionaleconomicassessmentofcostsvstimeeffectandimage 46TableB.12 Effectofrecognizingreclamationliabilitiesasincurredeffectandimage 46TableB.13 Characteristicsofmineableoilsandprojects 47TableB.14 Typicaltimelineforsiteuse 47TableB.15 Typicalstepstoscreentechnologyoptions 48TableB.16 Threeeconomicscreeningmethodsusedtoevaluatetailingsoptions 49TableB.17 Assigningacosttoreclamationobligations 53TableB.18 SuggestedprojectgoalsfortailingsR&D 55TableB.19 Typesofoilsandtailingsresearch 56TableB.20 Researchplayers,roleandsourceoffunding 56TableB.21 R&Dfunding 57TableB.22 Majortailingstechnologiesstudiedinlargescalefieldpilotprograms 58
ListofFigures
Figure# Title PageFigureB.1 HowAlbertasoilreservesrankwithworlddeposits 1FigureB.2 SatelliteviewoftheSyncrudeandSuncorBasePlants 3FigureB.3 Fiscalsharingvs.priceofoil 5FigureB.4 AerialviewSyncrudeMildredLakeSite 7FigureB.5 Proposaltocapweaktailings 9FigureB.6 MFTinventorytodate 9FigureB.7 Oilonthesurfaceofatailingspond 10FigureB.8 BedrockoftheMineableOilsandsArea 13FigureB.9 400tonminetruck 16FigureB.10 Loadinga400tonhaultruck 17FigureB.11 HowminingandtailingsworkinpitatSyncrude 18FigureB.12 Simpleextractionprocessflowsheet 19FigureB.13 ERCBbitumenextractionrecoverycurve 20FigureB.14 Theoilsandtailingscycle 23FigureB.15 Volumechangeonthepathfromoretowaste 23
-
ReportB:OverviewofOilSandTailings
The Rock DoctorOverviewofOilSandTailingsPagev
Figure# ListofFigures(continued) PageFigureB.16 PreparationofaconstructioncellatAlbianSands 25FigureB.17 Dozercompactingsandinaconstructioncell 26FigureB.18 Depositingconventionaltailings 27FigureB.19 Crosssectionofatailingsdamcentrelineconstructionmethod 31FigureB.20 Crosssectionofatailingsdamupstreamconstructionmethod 31FigureB.21 Changeindykedesignifconstructedofoverburden 32FigureB.22 Changeindesignifmaterialissolidvs.fluid 33FigureB.23 RelativevolumeofmineralsolidandwaterinMFT 34FigureB.24 Ternarydiagramforcharacterizingbehaviourofsoilslurries 40FigureB.25 Suggestedoffsettoprotectagainstlongtermgulleyerosion 43FigureB.26 Effectofdiscountfactorandtime 49
ListofAppendices
Appendix# Title Appendix1 Electronicdata,spreadsheetsandmodels 1. Workandcostsheetsforeachtechnologystudiedcontaining:
Workactivityvstime Capitalandoperatingcostvstime Reclamationactivitiesvstime Massbalances Userdefinedinputforcapitalandoperatingcosts Comparisonofunitcostforthetailingstechnologiesstudied
2. Fullprojecteconomicmodelthatconsiders Userdefinedinputfor
o Capitalconstructioncosto Productionvstimeo Incomefromproductsaleso Operatingcosts
Fiscalregimeconsideringroyalty,capitalallowances,provincialandfederalincometax
Inputforcapitalandoperatingcostforspecifictailingsoptions Treatmentofreclamationliabilities
Traditional(ignore),offsetagainstassetvalue,fundaQET. Cashflowtothedeveloper,provinceandfederalgovernment Rateofreturnfortheprojectandthedeveloper
3. TailingsforecastmodelUserinput Orecharacter Materialproperties Plantvariablesfinesdispersion,dischargedensityOutput Wastedepositssandandfluidtailsvolumes Waterlosshotwaterandoverallwaterloss
-
ReportB:OverviewofOilSandTailings
The Rock DoctorOverviewofOilSandTailingsPagevi
Appendices(continued) Appendix2 Drytailscase Appendix3 Definitions Appendix4 Materialpropertiesandbehaviour Appendix5 SuggestionsfortailingsR&D
-
B.1OilSandsBackground
The Rock Doctor B.1OilSandsBackground Page1
B.1IntroductionThissectionprovidesbackgroundinformationaboutAlbertasoilsands.Allinformationisfrompublicsources.
Theoilsandsareaworldclasssourceofoil.FigureB.1showshowtheresourcecompareswithotherworldsupplies.Somefactsabouttheresource
Resourcebase 1.7trillionbarrelsProvenreserves 170billionbarrelsrecoverableusingtodaystechnologyShallowmineable 35billionbarrelsProduction(2008) 1.3millionbarrelsperday Outlook 3millionbarrelsperdayby2018
FigureB.1HowAlbertasoilsandsrankwithworlddeposits.(AlbertaEnergy,2008).
Halfoftheoilsandproductioncomesfromshallowdepositsthataremined,thebitumenextractedusingahotwaterprocessandupgradedtoapipelineableproduct.
CharacteristicsofthreeoilsandprojectsaresummarisedonTable1.Theprojectsallstartedbigandaregettingbigger.Allhaveplanstoexpandtoproducehalfamillionbarrelsperdayinthenextfewyears.Syncrude,now30yearsold,expectstolastfor100years.
-
B.1OilSandsBackground
The Rock Doctor B.1OilSandsBackground Page2
TableB.1Characteristicsofthreemineableoilsandsprojects.
Project/Component Suncor Syncrude AlbianSandsStartupdate 1967 1978 2002Yearsinoperation 43 32 8Configuration Integratedfacility
MineMineWastedisposalExtractionUpgradingUpgraderTankfarmUtilitiesTailingsponds
IntegratedfacilityMineMineWastedisposalExtractionUpgrading
UpgraderTankfarm
UtilitiesTailingsponds
SeparatefacilitiesAtsiteMineExtractionWastedisposal455km24dilutedbitumenand12diluentreturnline.UpgraderatScotford(nearEdmonton)
Satellite MineandextractionsatellitesnearbyRemoteInsitu
Largesatellitecontainsmine,extraction,tailings
Expandingonsite
Startupproduction 45,000bblSCO/day 105,000bblSCO/day 150,000bblSCO/dayCurrentproduction 260,000bblSCO/day 300,000bblSCO/day 150,000bblSCO/dayPlannedproduction 500,000bblSCO/day 500,000bbl/day 500,000bbl/dayExtractionprocess Hotwater
UseNaOHdispersantHotwater
UseNaOHdispersantHotwater
Originallynodispersant.NowuseNaCitrate.Thickenerforheat
recovery.Extractionefficiency% 92% 90.7%
80%
(afterasphalteneloss)Upgradingyield 84% 87.5% 100%Cokeproduction 2milliontonnes/year 2.5milliontones/year Asphaltenesarerejected
andaddedtotailingsTailings ConventionalMFT
followedbyCTConventionalMFTfollowedbyCT
Producethickenedtails.LessMFTbecausenot
usingdispersant.GreenhouseGasTonnes/m3SCO
0.6 0.85 NA
VOCemission(kg/m3) 1.73 NA NANaphthaloss NA .0043bbl/bbl NAEnergyuseGJ/m3SCO 7.4 8.1 NAWaterimportm3/m3 2.4 2.03 NAWaterrecycle% N/A 88% NACumulativedisturbanceha 13,093 21,282 NACumulativeareareclaimed
949 4,668 NA
ReclamationCertificateha
0 104 0
-
B.1OilSandsBackground
The Rock Doctor B.1OilSandsBackground Page3
FigureB.1isanaerialviewofthebaseplantsforSyncrudeandSuncor.TableB.2summariseslanduseattheSyncrudebaseplant.Openpitmines,wastedumpsandtailingsfacilitiesdominatethelandscape.Thefootprintisjustundertwotownships.
TableB.2LanduseattheSyncrudeMildredLakeFacility(BasePlant) Landuse/area Ha %
Plantsiterelated 550 3%Mining Openpitspace 4,250 25% Overburdenwastedumps 1,100 6%Tailingspondsandrelatedareas 6,400 38%Miscellaneous 4,700 28%Total 17,000 100%
FigureB.2SatelliteviewofSyncrudeandSuncorbaseplants
-
B.2RegulatingOilSands
TheRockDoctorB.2RegulatingOilSands Page4
B.2.Regulatingoilsands B.2.1 Background OilSanddevelopmentisregulatedinAlbertabyAlbertaEnvironment(AENV),theEnergyResourcesConservationBoard(ERCB)andAlbertaSustainableResourceDevelopment(SRD).TheFederalgovernmentmanagesitsrolethroughEnvironmentCanadaandtheDepartmentofFisheriesandOceans.AENVandSRDhaveprimaryresponsibilityformanagingtheenvironment.Thatincludes,pollutionpreventionandcontrol,waterallocation,useandprotectionofpotablewater,conservationandreclamationplanning,andtheevaluationofair,water,andlandforenvironmentalperformancereporting.AENValsomanagesthefinancialassuranceprogramthatencompassesmanytypesofdevelopmentincludingoilsands.TheERCBregulatesoilsandsminingandprocessingoperations,aswellasdiscardfromthoseoperations,includingtailings.AMemorandumofUnderstanding(MOU)betweenAENV,SRDandtheERCBoutlineseachagencysresponsibilitiesandhowtheyworktogether.TheMOUaddressestailingspondsandotheraspectsofmineableoilsandsmanagement,includingwateruseandreclamation. B.2.2AlbertaEnvironmentalProtectionandEnhancementActTheAlbertaEnvironmentalProtectionandEnhancementActprovidesthemandateforAENV.(Alberta,1993).ThewritersinterpretationofsomeunderlyingprinciplescontainedoftheAct,thathaveadirectbearingonoilsandsmanagement,include:
Thepartythatdisturbslandisresponsibleforrestoringit.ThedisturberisobligedtoqualifyforaReclamationCertificatethatsignifiesthelandhasbeensatisfactorilyreclaimed.Thepublicisinvitedtoreviewandinputtodecisionsontheenvironment.Regulatorsmayrequiredeveloperstoprovidefinancialassurancethatfundswillbeavailabletoreclaimsites.Theformandamountoffinancialassuranceisattheregulatorsdiscretion.Thereistobenointergenerationaltransferofenvironmentalliabilities.
B.2.3ERCBMandateTheERCBmandateisgovernedbyTheAlbertaOilSandsConservationAct.ApprovalsforminesandplantsarerequiredbySections10and11oftheAct.Approvaltocommence,suspend,orabandonanoilsandssiteisrequiredbySection3.ApprovalforstorageofdiscardgeneratedbyamineoraplantisrequiredbySections24and48.
-
B.2RegulatingOilSands
TheRockDoctorB.2RegulatingOilSands Page5
In2004theERCBandtheCanadianEnvironmentalAssessmentAgencyidentifiedseverallongtermobjectivesrespectingtailingsmanagement:
tominimizeandeventuallyeliminatelongtermstorageoffluidtailingsinthereclamationlandscape;tocreateatrafficablelandscapeattheearliestopportunitytofacilitateprogressivereclamation;toeliminateorreducecontainmentoffluidtailingsinanexternaltailingsdisposalareaduringoperations;toreducestoredprocessaffectedwastewatervolumesonsite;tomaximizeintermediateprocesswaterrecyclingtoincreaseenergyefficiencyandreducefreshwaterimport;tominimizeresourcesterilizationassociatedwithtailingsponds;andtoensurethattheliabilityfortailingsismanagedthroughreclamationoftailingsponds.
InFebruary2009theERCBissuedDirective074.Itrequiresoilsandoperatorstosolidifyincreasingamountsoffluidtailingseachyear,reportonfinesmanagement,andreportontheperformanceofeachtailingsfacilityannually.
-
B.3FiscalTermsforOilSands
TheRockDoctorB.3FiscalTermsforOilSandsPage5
B.3.FiscalTermsOilsandprojectsarehighlytaxedsothefiscalregimeisveryimportant.IndividualcomponentsofthefiscalregimeincludeAlbertaroyalty,capitalinvestmentincentives,andfederalandprovincialincometax.AlbertaRoyaltyvarieswiththestageofaprojectandthepriceofoil.Beforepayout,AlbertaRoyaltyisapercentageofGrossincome.Afterpayout,AlbertaRoyaltyisthegreaterof:aspecifiedpercentageofnetprofit,orapercentageofgrossincome.
Payoutoccurswhencumulativeincomeexceedscumulativeexpenditures.
Afterpayout,adollarofprofitissharedaccordingtofiscalterms,asgraphedonFigureB.3.Dependingonthepriceofoil,fiscalsharingleavesthedeveloperwith$0.45to$0.56fromeachdollarofprofit.Governmentsreceivetherest.Ifmoneyisspent,thesamefiscalsharingoccurs.Thenthecosttothedeveloperofspendingonedollaris$0.45to$0.56.Throughforegoneprofits,thegovernmentspaytherest.Fiscalsharingisanimportantpartofoilsandeconomicsandmustbepartofanyeconomicassessment.
0%
10%
20%
30%
40%
50%
60%
$40.00 $60.00 $80.00 $100.00 $120.00 $140.00 $160.00
Shareof
profit
and
expen
se%
PriceofOil$/bbl
FigureB.3Fiscalsharingvs priceofoil
AlbertaRoyalty
FederalIncomeTax
AlbertaIncomeTax
Developer
AllGovernmentCombined
-
B4Evolutionoftailingsandreclamationprocesses
The Rock DoctorB.4Evolutionoftailingsandreclamationpractices Page6
B.4Evolutionoftailingsandreclamationpractices
B.4.1EarlyHistory
Tailingspracticehasevolved.TherewerefewenvironmentalguidelineswhenSuncorstartedoperationsin1967.Thatwas5yearsbeforeAlbertaEnvironmentexisted.
TailingswereasurprisewhenSuncorstartedoperationsin1967.AtemporarydykewasconstructedtoTarIslandintheAthabascaRivertoholdthetailingsuntilasolutioncouldbefound.Todaythedykesofthatfacilityare100mhighanditisbeingreclaimedafter42yearsofservice.
Todayapplicationsforoilsandsdevelopmentareobligedtostudythelease,identifyallpotentialadverseimpactsandshowhowtheywillmanagethem.Theyarealsoobligedtosubmitalongtermclosureplan.Attheendoftheprojectoperatorsareexpectedtoreclaimthesiteandqualifyforareclamationcertificate.TheReclamationCertificateisissuedbythegovernmentandmeansthatreclaimedlandsareacceptabletotheregulatorsandthatthedeveloperisnolongerresponsible.
B.4.2The1990s
InitiallyallofSyncrudestailingswerestoredintheMildredLakefacility.
After10yearsofoperation,SyncrudeintroducedapumparoundsystemtopreventtheMildredLakefacilityfromfilling.(Listetal,1995).ItisillustratedbyFigureB.3.Thesystemworksasfollows:
PlantwasteispumpedtotheSouthWestSandStoragefacilitywheresandisdeposited.ThintailsrunoffispumpedtotheMildredLakeSettlingBasin.
AttheMildredLakefacility,finessettleandformMFT. MatureMFTispumpedfromtheMildredLakeSettlingBasintotheBaseMineLakestorage. MFTformakingCTisrecoveredfromtheMildredLakefacilityorfromtheBaseMineLake. CTisstoredintheactiveCTtailingsrepository.
InthesameperiodSuncordevelopednewfacilitiestoholdfluidtailingsinminedoutareas.FigureB.2showshowtailingspondsdominatetheSuncorbaseplantsite.
-
B4Evolutionoftailingsandreclamationprocesses
The Rock DoctorB.4Evolutionoftailingsandreclamationpractices Page7
MLSB
SWSS
BML
EIP
Baseminelake
FigureB.4AerialViewSyncrudeMildredLakeSite
SiteBoundary
SuncorBoundary
MildredLakesettlingbasin
EastInPit
Southwestsandstorage 10km
.
InSyncrudes1992applicationforprojectexpansionSyncrudeproposedto:
DecreaseMFTproductionthroughanumberofinhouseinitiatives. SolidifyMFTusingtheCTprocess. PermanentlystoreMFTthatremainsattheendofoperationsbelowawatercapinanendpit
lake.TheyproposedafullscaledemonstrationtestintheBaseMineLakecommencingin2012.Thedemonstrationwouldlastfor10to15years.
TheERCBagreedtothedemonstrationtestprovidedthefacilitywouldbereclaimedifthetestwasnotsuccessful.TheERCBnotedthattheypreferredthatfluidtailingsbereclaimedasatrafficablesolid.TheyalsonotedthattheproposaltopermanentlystoreMFTunderawatercapwasnotapproved.(Houlihanetal,2008).
SinceSyncrudeproposeditin1992,mostoilsandapplicationshaveproposedtostartwithasurfacetailingspond,andthenswitchtoCTorequivalentwhentheprojectmovesinpit.Attheendoftheproject,fluidtailingsleftoverwouldbestoredpermanentlyunderawatercap.Thelistoflookalikeapplicationsinclude:
Syncrudeapplications(Syncrude1992,2002) Suncorapplications(ERCB2003,2004) Shelloilsandapplications(AlbianSands,2002,2003) KearlLakeapplication(Kearl,2005).
-
B4Evolutionoftailingsandreclamationprocesses
The Rock DoctorB.4Evolutionoftailingsandreclamationpractices Page8
Syncrudesinhouseinitiativesprogramwasimplementedandwaslargelysuccessful.Themainprograminvolvedreducingthewatercontentintheextractionplantandinthetailingsdischargesofinescaptureinthesanddepositswouldbemaximized.FinesthatarecapturedinthebeacharenotavailabletomakeMFT.SyncrudesuccessfullyoperatedsmallscaledemonstrationtestswithwateroverMFT.However,thetestsweresmallanddidnotevaluatetheeffectofgasemissionsthatstartedatalaterdate.SyncrudeevaluatedCTina5millioncubicmetredemonstrationpilotinthemid1990s.TheystartedusingCTincommercialoperationsin1999.ThatdepositisbeingpreparedforreclamationthefirsttailingspondtobereclaimedatSyncrude.(Fair,2008).
SuncorhavebeenusingCTincommercialoperationssincethe1995.(Shaw,2008).Suncorarereclaimingtheirstartuppondthathadbeeninuseforover40years.
B.4.3RecenteventsIndustryappearstofocuson:
Traditionalplantstomakefluidtailingsuntiloperationscanmoveinpit; ThensolidifyfluidtailingsusingCToranequivalenttechnology; Permanentlystoreresidualamountsoffluidtailingsunderawatercappedendpitlake.
ThatisastrongcontrasttothegoalssetoutbytheERCB(Houlihanet.Al.2008):
Minimizeandeventuallyeliminatelongtermstorageoffluidtailings.Createatrafficablelandscapeattheearliestopportunity. Eliminateorreducefluidtailingsinanexternaltailingsdisposalarea. Ensurethattheliabilityfortailingsismanagedthroughreclamation.Pilotresearchisapparentlyevaluatingothertechnologiessuchassandstacking,thickenerevaluations,cyclonetreatment,drying,freezethawtreatmentandcentrifugetreatment.(Fair,2008).Suncoraremanyoftheaboveaswellasselfcontainedmobilemine/extractionunits.GeneralinformationabouttheSyncrudeorSuncorresearchhasbeenreleasedbutlittleifanyspecificshavebeenmadepublic.Shellareresearchingthickenedtailingsoptions(Matthews,(2008)).Theystartedtheiroperationwithouttheuseofdispersingagentstoreducetailingsproduced.However,theyhavesubsequentlybeenaddingsodiumcitrate,adispersant.Shellarestillproducingthickenedtailingsandstoringitintheiroutofpitstarterpond.InthepastdecadeSyncrudeproducedabout200millioncubicmetresofMFT.TenpercentofthatwassolidifiedwithCTtreatment.(Fair,2008).
-
B4Evolutionoftailingsandreclamationprocesses
The Rock DoctorB.4Evolutionoftailingsandreclamationpractices Page9
MFTstorageinterfereswithlandreclamation.Syncrudehavedisturbedovertwotownshipsoflandarea.20%hasbeenreclaimed.Suncorhaveonlyreclaimed4%oftheirdisturbedlands.Todate104hectaresintheoilsandregionhavereceivedformalreclamationcertificates.TheTotalapplication(Total,2006a,2006b)proposetostoreweakCTatdepth,coveritwithstrongerCTallofwhichwillbecoveredwithastrongsandcap.(Total2006b).FigureB.5illustratestheTotalproposal.
HighFinesCT Weakdeposit
Dyke Dyke
Strongcap
Workingsurface
LowfinesCT
Reclaimedsurface
FigureB.6Proposaltocapweaktailings
FigureB.6showsthegrowthofMFTforthewholeindustry.Todaythevolumetotals750millioncubicmetres.IfthereisnochangeinprocessesusedthevolumeisforecasttoreachIbillioncubicmetresin2014andtwobillionin2034.(Houlihanet.al.2008).
Figure B.6 Regional MFT Inventory to date
-
B4Evolutionoftailingsandreclamationprocesses
The Rock DoctorB.4Evolutionoftailingsandreclamationpractices Page10
B.4.4500Ducks OilsandsdevelopmentsarelocatedonamajorflywaythatbirdsuseastheymigratetonestingsitesintheArctic.Millionsofbirdsflyovertheoilsandsdevelopmentseachspring,andreturnwiththeiryoungeachfall.Tailingspondsareincompatiblewiththisnaturalmigrationbecausebirdsthatlandonthepondsareapttobecomeoilcoveredanddie.FigureB.7showsoilonthesurfaceofaSyncrudetailingspond.
FigureB.7Oilonthesurfaceofatailingspond
Deterrentssuchasmansizedstatuesstandingonfloatsspacedatregularintervalsonthepondsurfaceareusedtokeepthebirdsfromlanding.Thestatuesaresupplementedbypropane"cannons"thatfireatregularintervalsandmimicshotgunblasts.AlbianSandsusearadarscannertodetectincomingbirdsandactivateanartificialhawktoscarebirdsaway.InApril2008,latewinterstormsdelayedinstallationoftheseasonalduckdeterrents.AflockofMallardduckslandedonaSyncrudetailingspondbeforethedeterrentswereinstalled.500+ducksperished.
Adverseworldwidepublicityfollowed.Internetsearchesrevealaplethoraofantioilsand,antiCanada,andantiU.S.A.websites,books(Nikiforuk,2008),andmagazines(Kuneig,R.,(2009),NationalGeographic).Thepublicitymayexaggerateandsupportotheragendasonenergyuseandclimatechange.However,someoftheconcernsarejustifiedandrevealanoilsandindustryoutlookthat,ifSyncrude's2006C&RPlanisamodel(Syncrude,2006),wassadlyoutofdate.Theimpactisdamagingthemarketabilityofoilsandsproducts,andCanada'simageinworldtrade.
-
B4Evolutionoftailingsandreclamationprocesses
The Rock DoctorB.4Evolutionoftailingsandreclamationpractices Page11
B.4.5ERCBDirective074In2008theERCBheldmeetingswithoilsandoperatorstoshareconcernsaboutthegrowinginventoryoffluidtailingsandtodiscussnewreportingrequirements.InFebruary,2009theERCBissuedDirective074.Itrequiresoperatorstoreportonallfinesprocessedandtosolidifyincreasingpercentagesofthefinesprocessedeachyear.(20%,30%,and50%inthenextthreeyears).TheDirectivespecifiesstrengthcriteriaforthesolidifiedfines(aminimumundrainedshearstrengthof5kPainthefirstyearandaminimumof10RPaafter5years).Inaddition.Directive074requiresthatoperatorsinventorytheirtailingspondsandreportperformanceannually.HoulihanpresentedasummaryofthepublicandregulatoryconcernsabouttailingsthatwerebehindDirective074(Houlihanetal,2008).Publicconcerns:
Seepageandpotentialwatercontamination,Fugitiveemissions,Riskofatailingsdamfailure,Returnofthelandtotraditionaluse,Progressivereclamation(lackofit),Intergenerationaltransferofliability.
Regulator'sconcerns:Applicationsunderestimatethefluidtailingsvolumes,CTperformancetargetsandcommitmentsnotmet,Fluidvolumesgrowingsteadily,Nofluidtailingspondreclaimed,Neitherthepublicnorthegovernmentispreparedtoacceptcommitmentsthatarenotmetandincreasingliabilities.
Historicallythegovernmenthasencouragedindustrytoshowleadershipinoilsandsmanagement.Directive074representsanewdirection.
-
B.5OilSandGeology
The Rock DoctorB.5OilSandGeologyPage12
B.5OilSandGeology B.5.1ResourceBasemineablearea
TheERCBestimatesthat35billionbarrelsofbitumenisrecoverablefromthesurfacemineablearea(ERCB,(2009b)).
Formineabledevelopmentstheminimumresourcebaseisenoughtosupportaprojectfor25years.Thatamountstoover1billionbarrelsofreservesper100,000barrelsofproductionperday..
B.5.2BedrockGeology
Themineableoilsandareaisdefinedasoilsandthathasupto50metresofoverburdenovertheorezone.ItislocatednorthofFortMcMurray.FigureB.8showsthedistributionofbedrockformationsintheFortMcMurrayarea.(Alberta,2009)GraniteoftheCanadianShieldliesundertheoilsandareaafewhundredmetresbelowsurface.ThegraniteiscoveredbyPaleozoicformationsofsandstone,salt,shale,limestoneanddolomitethatdipgentlytothewest.TheMcMurrayFormationisthehostrockforbitumen.ItwasdepositedunconformablyontopofthePaleozoicformations.ItisofCretaceousage,(120millionyearsold).Depositionalenvironments,createdwhenashallowseainvadedthearea,leftcomplexlyinterlayereddepositsofsand,siltandclay.TheClearwaterformationwasdepositedontopoftheMcMurray.Itcontainsmarinedepositsthatformedinthedeepenedsea.SomelayersoftheClearwateraresandybutmostareclayshalethatcontainsconsiderableamountsofbentonite.OtherformationsfollowedsoatonetimetheMcMurraywascoveredbyonetotwokilometresofsediment.
B.5.3Localstructure
SolutionofthesaltbedswasoccurringinduringCretaceoustime,especiallyeastoftheAthabascaRiver.Solutionactivitydisruptsthecontinuityofoverlyingbeds.ThickenedsectionsoftheMcMurraydevelopedinareasthatweresubsidinginCretaceoustime.Karstfeatures,evidentonsurfacetoday,indicatethatsolutionactivityiscontinuing.(Fraser,1975).
-
B.5OilSandGeology
The Rock DoctorB.5OilSandGeologyPage13
FigureB.8 BedrockoftheMineableOilSandsArea
-
B.5OilSandGeology
The Rock DoctorB.5OilSandGeologyPage14
TheBitumontbasindevelopednorthofSuncorandSyncrude.ItisindicatedonFigureB.8bythecircularareaoccupiedbyClearwaterclay/shale.Theretheentireprofile,includingthegranitesurfacesubsided,indicatingthattheoriginismoredeepseatedthansolutionofsaltbeds.SubsidenceduringMcMurraytimeresultedinthickerandcoarserbedsofsand.Subsidenceafteroilenteredtheareadepressedpartsofthebitumensaturatedzone30metresbelowtheAthabascaRiver.(Isherwood,2009).
B.5.4OriginofthebitumenAtanunknowntime,conventionaloilfromtheAlbertaBasinmigratedeastwardintothearea.Itfloatedonawaterlayer,andfilledthetopoftheMcMurrayformation.Bacterialactionstrippedlightcomponentsfromtheoil,leavingheavybitumen.(McNeely,1973).Thebitumen/waterinterfacetendstobehorizontalintheSuncorarea,coincidingwiththepresentleveloftheAthabascaRiver.IntheBitumontBasinthebitumensaturatedzoneisdepressedabout30metresbelowtheAthabascaRiver.
B.5.5SurficialGeologySurficialdepositsincludePleistoceneglacialtillbothdensebasaltillandweakerablationtill.Outwashdeposits,windblownsandsandlacustrinedepositsfollowedatthecloseofthePleistoceneglaciation.Surfacedepositsincludelocalalluviumandmuskegdeposits.Continentalglaciationsmeltedfromsouthtonorth.Thenorthernsectionsblockeddrainagesolargelakesformedsouthoftheicesheet.GlacialLakeAgassizcoveredmuchofManitobaandSaskatchewan.About10,000yearsagoitdischargeddowntheClearwaterRiverandcarvedthepresentvalleyoftheAthabascaRivernorthofFortMcMurray.(Smithet.al.,1993).UpstreamfromFortMcMurraytheAthabascaRiverflowsonbedrock.DownstreamfromFortMcMurraythereisaburiedvalleybelowtheAthabascaRiver.TheburiedvalleyNorthofNorthofFortMcMurrayprobablyrepresentsapreCretaceousrivervalley(Devenny,2000).ContinuingsaltsolutionisindicatedbysaltspringsthatentertheAthabascaRiverespeciallyneartheBitumontBasin(Bauman,2008).UpstreamfromFortMcMurraytheAthabascaRiverflowsonthesurfaceofPaleozoicbedrock.DownstreamfromFortMcMurraythereisaburiedvalleybelowtheAthabascaRiver.TheburiedvalleyNorthofNorthofFortMcMurrayprobablyrepresentsapreCretaceousrivervalley(Devenny,2000).ContinuingsaltsolutionisindicatedbynaturalsaltspringsthatentertheAthabascaRiverespeciallyneartheBitumontBasin.(Bauman,2008).
B.2.6Orebodycharacter
-
B.5OilSandGeology
The Rock DoctorB.5OilSandGeologyPage15
Inthemineableoilsandsarea,overburdentendstobeabout50metresthick.Theorezonealsotendstobeabout50metresthick.Oregradesarehighestinsandyzones(ashighas15%byweightbitumen)andlowestwherefinegrainedmaterialispresent.Table3.characterizesaverageoreatSyncrude.TableB.3AverageoreusedinthestudyreportedinReportA
Component Weight% Weightpercubicmetre(tonnes)
Volumeinonecubicmetre
Density/specificgravity
Bitumen 11% 0.231 0.229 1.01Water 5% 0.105 0.105 1.00Fines 16% 0.336 0.127 2.65Sand 68% 1.428 0.539 2.65Total 100% 2.100 1.000
ThefollowingdiscussiondealswithfactsaboutaverageorethatwecaninterpretfromTableB.3.
1. TheBitumendensityisveryclosetothedensityofwater.Thatchallengesseparationinextractionandisthereasonthatairbubbleassistanceisusedtofloatbitumen.Itisalsothereasonthatsolventisusedtochangethedensityofbitumeninfrothtreatment.
2. Bitumenrepresents22%ofthetotalvolumeofoilsandore.Thatsuggestsacleanporoussand.3. Theclay/waterratioislowindicatingthatinsitutheclayisnotdispersed.
Otherfactsaboutoilsandore:
4. Oilsandoreishighlyvariable,aresultofthevariabledepositionalenvironmentsofthehostreservoir.Itcontainscomplexlyinterlayeredoreandwastedepositsofsand,silt,andclay.Allprocesses,fromtheminefacethroughextractionandtailings,mustberobustandabletoaccommodatevariationsintheore.
5. Quartzandclaymineralsilmeniteandkaolinarethedominantmineralsinoilsand.6. Aquartzsurfacehasagreateraffinityforwaterthanbitumen.Asaresulteachsandgrainis
surroundedbyathinfilmofwaterthatallowseasyseparationviaagitationinhotwater.Oilsanddepositselsewhereintheworldareoftencomposedofothermineralsthatattractbitumentothesandgrainsurface.Theyrequiresolventtoextractthebitumen.
7. Bitumenparticlesreleasedinextractionreflectthesizeofthevoidspacethattheyarereleasedfrom.Insandthevoidspaceisquitelarge.Infinegrainedsoilthevoidspaceisquitefine.
8. Bitumenassociatedwithfinegraineddepositscanbedifficulttoextractbecause: Thesurfacemaybeoilwet, Bitumendropletsaretoofineforairbubblestocontactandfloatthemtosurface.
9. Thereareminorquantitiesofheavymineralsilmenite,rutileandzircon.Centrifugeactioninextractionconcentratestheheavymineralsmanyfoldsotheyarepotentialoresfortitaniumandzirconium.
10. Bitumencontainscoproductssulphur,cokeandvanadium.
-
B.6MiningOilSand
The Rock DoctorB.6MiningOilSandPage16
B.6MiningAllprojectsmineoverburdenandoreusinglargeshovelsand400tontrucks.Oreishauledtoadumpfacilitywhereitiscrushed,screened,slurriedwithwarmprocesswaterandpumpedtotheextractionplant.Turbulenceduringhydrotransport,breakstheoreintoindividualparticlesneededforseparationinextraction.Processaids,dispersingagentsandsmallairbubbles,areaddedbeforetheorereachesextraction.Minewaste(overburdenandinterburden)ishauledtowastedumps.Suitablewasteisalsousedtoconstructfacilitiessuchastailingsdykes.Itisusuallycompactedbydriving400tontrucksoverit.Somewastesareunsuitableforconstruction,becausetheyaretoowet,orcontainundesirablematerial(e.g.swellinganderodibleclaysoftheClearwaterFormation.)Careisrequiredtoensurethatmaterialsthataredeleterioustoextractionarekeptoutoftheoresupply.DeleteriousmaterialsincludeactiveclayfromtheClearwaterFormation.FigureB.8showsa400tontruckthatisusedinoilsandmining.FigureB.9showsashovelloadingoreontoa400tontruck.Shovelsaresizedsotheycanfillthetruckswiththreescoops.
FigureB.9400tonminetruck
ERCBInterimDirectiveID20017stipulatescutoffcriteriaformining.ProjectsareexpectedtominetoaminimumTV/BIPof12whereTVisthetotalvolumeofore,interburdenandoverburden,andBIPisthevolumeofbitumeninplace.Theminimumwastelayeris3metresthick.Thecutoffgradeis7%.
-
B.6MiningOilSand
The Rock DoctorB.6MiningOilSandPage17
Mineopeningsmustdepressurizeaquifersencounteredinandbelowtheorebody.AttheSuncorandSyncrudebaseplantsgroundwateraquifersarelimitedandtheoreseldomdipsbelowtheleveloftheAthabascaRiver.AtAlbianSandsthebasalaquiferismoreextensivebutminingactivitytendstobeabovetheleveloftheAthabascaRiver.ProjectsinandneartheBitumontBasincouldbeminingore30metresbelowthesurfaceoftheAthabascaRiver.Groundwatercontrolinthoseminescouldencounterlargequantitiesofverysalinewater.
FigureB.10Loadinga400tonhaultruck
Minedoutareasarebackfilledwithoverburdenandtailings.FigureB.11showshowtailingsandminingactivityexistsidebysideatSyncrude.Itcantake50yearstoaccommodatemining,tailingsstorage,tailingsreclamationandfinallysurfacereclamation.Therearewasteproductsthatmustbeaccommodatedinminedoutareas:
Overburdenandinterburdenwaste, MaterialrejectedatthescreenbeforeHydrotransport(cementedlayersandclaylumps), Cokeproducedinupgrading(approximately2milliontonnesperyearatbothSyncrudeand
Suncor).TheERCBrequiresthatcokebeplacedsoitwillbeaccessibletofuturegenerations.
Sulphur(usuallystoredonsitebecauseshippingcostexceedsthemarketvalue).Sulphurisalsostoredsoitwillbeaccessibleinthefuture.
-
B.6MiningOilSand
The Rock DoctorB.6MiningOilSandPage18
FigureB.11HowminingandtailingsworkinpitatSyncrude
Legend
EIP EastinPitMineSWIP SouthWestinPitmineNorthMineActiveNorthMine
-
B.7Extraction
The Rock DoctorB.7ExtractionPage19
B.7Extraction
FigureB.11showsasimplifiedprocessflowsheetforanoilsandextractionplant.
MiddlingsTreatment
FigureB.5SimpleExtractionProcessFlowSheet
Mixer
MineSlurry CrushScreenHydrotransport
FrothCleaningPSVDesander
FloodWater
ToTailingsToTailings
Froth
Thefirststepinextractionistoaddwatertotheincomingoreslurry.Thefirstvesselintheextractionplantcontainsrelativelystillwater.Inthatenvironmentsanddropsoutofsuspensionandissenttotailings.Bitumen,aidedbysmallattachedairbubblesfloatstothesurfacewhereitisremovedasfroth.Theremainingmixtureiscalledmiddlings.Itcontainswater,silt,clay,andsmalldropletsofbitumen,issenttothenextstageoftheextractionplantforfurtherprocessing.Afterbitumenhasbeenremovedfromthemiddlingscircuitresidualwasteisblendedwiththesandtailingsstreamandsenttotailings.Infrothtreatment,solventisaddedtodilutebitumenandtochangeitsspecificgravity.Thentheslurryiscentrifugedtoseparatethebitumenfromwaterandsolids.Residualwastecontainingwater,solids,unrecoveredbitumenandsolventlossesisdischargedasfrothtreatmenttailings.
-
B.7Extraction
The Rock DoctorB.7ExtractionPage20
Frothtreatmenttailingscontainthemostbitumenandsolventaswellasconcentrationsofheavymineralssuchasilmenite,rutileandmonazite.Thereissomeinterestinilmeniteandrutileaspotentialsourcesoftitanium.Monazitecontainsradioactiveelementsthataredetectablewithgeophysicalloggingtools.Blendingfrothtreatmenttailingswithregulartailingsdegradesthequalityofregulartailings.Italsowastesconcentratedilmeniteandrutile,andaddsconcentrationsofradioactivitythatinterferewithusinggeophysicaltoolstodeterminetheclaycontentofMFT.Perhapswastefromfrothtreatmentshouldbestoredseparately.
Theextractionsystemsdescribedareillustrative.Otherconfigurationsarealsoused.
ERCBInterimDirectiveID20017specifiestheminimumbitumenrecovery.Fororethatcontainsmorethan11%byweightbitumen,extractionisexpectedtorecover90%ormoreofthebitumen.Fororegradesbetween7%and11%theminimumbitumenrecoverycurveisindicatedbyFigureB.13.
30%
40%
50%
60%
70%
80%
90%
100%
6% 7% 8% 9% 10% 11% 12% 13% 14%
Minim
umRecovery%
OreGrade%
Figure6ERCBBitumenExtractionRecoveryCurve
ERCBRecoveryCriteria
Maximumore/rejectthickness3mCutoffgrade
7%TV/BIP Cutoff 12
Minimumrecoveryinextraction(Recovery=54.1X 2.5X2 202.7)whereX=feedgrade
SuncorandSyncrudeoperateintegratedplants.Theyproducebitumenthatissuitablefortheironsiteupgraderbutdoesnotmeetspecificationsforpipelinetransport.Table1indicatesthatSuncorandSyncruderecover92%and90.7%ofthebitumeninextraction.ThedifferenceprobablyreflectsslightlylowergradeoreatSyncrude.
-
B.7Extraction
The Rock DoctorB.7ExtractionPage21
TheAlbianSandsProjectproducesbitumenandthenshipsit455kmtotheShellupgraderinScotfordAlberta.PipelinespecificationsrequirecleanerbitumenthanSyncrudeandSuncorproduce.Thenewfrothtreatmentusedtoproducecleanbitumencausesasphaltenestoprecipitate.Theyareaddedtotailingsfromfrothtreatment.AsaresulttheoverallhydrocarbonrecoveryatAlbianSandsisprobably80%orless.
SuncorandSyncrudeaddcausticsodainextractiontofacilitatebitumenremoval.Causticsodaalsodispersesclay.Thataddstothevolumeoffluidtailingscreated.
Originally,AlbianSandsproposedtooperateextractionwithoutaddingdispersingagents.Thereason:anticipatedsuperiorperformanceintailingsdenser,rapidlysettlingtailings,andfasterwaterclarification.However,theprojectnowaddssodiumcitrate,adispersingagent,toaidbitumenextraction.
Processwaterdischargedinthewastestreamsfromextractioncontainsheat.Heatlossisreducediftheamountofwaterdischargedwithplantwasteisreduced.
Waterdischargecanbereducedbyconcentratingthesolidcontentofthedischargestreams.Thefinesstreamcanbeconcentratedtoabout30%solidsinathickener.Thesandwastestreamcanbedensifiedbycyclonestoover70%solids.Processwaterrecoveredintheplant,withitscontainedheat,isimmediatelyrecycledandreused.
Traditionalextractionproduceswastethatcanbepumped.Theupperlimitforthestrengthofpumpablewasteis100kPa.Thatis1%ofthestrengthdesiredforreclamation.
-
B.8BasicTailingsfromExtractiontoMFT
TheRockDoctorB.8BasicTailingsfromExtractiontoMFTPage22
B.8BasicTailingsfromextractiontoMFT
B.8.1IntroductiontoTailings
Tailingsarethewasteproductofoilsandprocessing.
Theassignmentfortailingsmanagementis:
1. Receiveallsolidandfluidwasteproducedbyextraction,2. Storeitinasafe,costeffectivemanner,3. Returnclarifiedprocesswatertotheplantforreuse,4. Reclaimwastedepositstomeetreclamationrequirementsforclosureinatimelymanner.
Theassignmentisadifficultonebecause:
Tailingswasteisreceivedasaliquidslurry. Azerodischargepolicyrequiresthatallprocessaffectedwaterberetainedonsite. Forclosure,someofthewastemustbetransformedintoastrong,selfsupportingsolid. Extractiondonotknowtheclaycontentoftheirtailingsdischarge.
B.8.2Thetailingscycle
FigureB.14showsthestepsinthepaththattransformsoretotailings.FigureB.15showstherelativevolumeofthecomponentsoftailingsalongthatpath.Stepsintailingsmanagementaredescribedbelow:
Oreismined,slurriedandpumpedtoextraction.Intransittheoreseparatesintoindividualparticles,inpreparationforbitumenextraction.Thevolumeofsolidsremainconstantfromstagetostage.Volumechangesareduetobitumenremoval,wateradditionandwaterremoval.
Inextractiontheorecomponentsareseparatedintothreestreams(coarse,finesandfroth)becauseeachrequiresdifferenttreatment.Afterbitumenhasbeenextracted,thesandandfineswastestreamsarecombinedandpumpedtothetailingsdisposalsite.Frothtreatmentwastemaybepumpeddirectlytothetailingspond.Wasteslurriessenttotailingscontainprocesswater,sand,fines,unrecoveredbitumen,andminorimpuritiesfromnaturalandmanmadesources.Whentailingsexittheplantthevolumeoftheslurryismorethantwicetheoriginalvolumeoftheore.Heatlossisassociatedwiththelargevolumeofwaterinthetailingsslurry.
-
B.8BasicTailingsfromExtractiontoMFT
TheRockDoctorB.8BasicTailingsfromExtractiontoMFTPage23
MFT
NativeSoil
SolidFineTails
WaterClarificationZone
BeachSand
SandDyke Beach
Sand
SandDyke
ProductOre
BitumenWaterFinesSand
WaterfromSFT
MakeupWater
Hydrotransport
OverflowToPond
ExtractionPlant
RecycleWater
7
6
54
3
2
1FigureB.14TheOilSandsTailingsCycle
0
0.5
1
1.5
2
2.5
3
ChartTitle
Bitumen
Water
Fines
Sand
FigureB.15Volumechangeonthepathfromoretowaste
-
B.8BasicTailingsfromExtractiontoMFT
TheRockDoctorB.8BasicTailingsfromExtractiontoMFTPage24
Atthewastestoragesite,theslurryisdischargedontoasanddeposit.Seventyfivepercentofthewasteaccumulatesasasolidsanddeposit.Voidspaceinthesandisfilledwithwaterandsuspendedcomponents.Thevoidspaceinthesandisalmostequaltothevolumeoffluidtailings.Surplusmaterialoverflowstothepond.
Materialenteringthetailingspondconsistsofadilutesuspensionofwater,fines,unrecoveredbitumenandsolvent,andimpurities.SectionB.A4.3inAppendixB.4describeshowsolidssettletobecomeMFT.
MosttailingsmaterialbalancesinApplicationsforacommercialdevelopmentstopattheMFTstage.FiguresB.14andB.15assumethatclosurerequiresthatMFTshouldbereclaimedassolidfinetailingsorSFT.ThefinalstepchangesMFTtoSFTwithafinesdensityof70%solidsbyweight.
Surpluswaterinthepondisavailableforreuse.WhenthefinesarestoredasMFTthevolumeavailableforrecycleis1.15cubicmetrespercubicmetreofaverageoreprocessed.ConvertingMFTtoSFTaddsanadditional0.18cubicmetresofwatertorecycle.
Dissolvedsaltsaccumulatewitheachtimewaterisreused.Thesaltscomefromconnatewaterintheore,minedepressurizationwater,andprocessaids.
Lord(Lordetal,1997).reportsMFTdensitiesof35%andeven40%atSyncrude.Thedensitiesnotedindicatethatsomeconsolidationistakingplace.TherearesubtledifferencesinMFTatSyncrudeandSuncor(McKinnonetal,1993).Theprecedingfactsdonotchangethethrustofdiscussionsinthisreport.
Tailingswaterbecomessaltierwithreuse.Implications:
Atsomepointthewaterchemistrywillcauseclaytoflocculateinextractionhaltingbitumenextraction.
Saltyprocesswatersuppressesvegetationsoadverselyaffectsreclamation. Itwillbedifficulttoassimilatetailingswaterinthesurroundingsifitistoosalty.
B.8.3Transportingtailings
Processwasteisblendedandpumpedtothetailingsdisposalsiteforseveralreasons:
Finegrainedcomponentsassistfluidtransportofsand. Blendedwastemeansthatonlyonetransportsystemisneeded. Wasteispumpedbecauseitisbelievedtobethelowestcosttransportsystem. Dischargedwasteautomaticallyflowstoitsfinalrestingplace.
-
B.8BasicTailingsfromExtractiontoMFT
TheRockDoctorB.8BasicTailingsfromExtractiontoMFTPage25
Tailingsispumpedataspeedof3to5metrespersecondtokeepallsolidsinsuspension.
Theupperlimitonstrengthforpumpedslurriesisabout100kPa.Thestrengthofthepumpedmaterialwillhavetoincreasebyafactorof100toequal10kPa,thelowerlimitofstrengthdesiredforsolidreclaimabletailings.
Tosaveheat,operatorstrytokeepthedensityofthewasteslurryhigh(between50%and60%solids).Itisnotpracticaltopumpathigherdensities.
B.8.4TailingsSanddeposits
Threetypesofsanddepositsformattheendofthetailingsline.
Sandconstructioncell
Largecellsarecreatedtocollectsandforconstruction.Whenthetailingsslurryentersthebroadcell,flowvelocitydecreasesandsanddropsoutofsuspension.Dozersmaintainsmallperimeterdykesaroundthecellandcompactthenewlydepositedsandbytrackingbackandforthacrossit.Voidspaceinthesandisfilledwithprocesswaterandsuspendedmaterial.
FigureB.16isaphotoofatailingssandcellinpreparation.FigureB.17isaphotoofadozercompactingsandintheconstructioncell.(Matthews,2008).
FigureB.16PreparationofaconstructioncellatAlbianSands
-
B.8BasicTailingsfromExtractiontoMFT
TheRockDoctorB.8BasicTailingsfromExtractiontoMFTPage26
FigureB.17Dozercompactingsandinaconstructioncell
Sandthatisnotusedforconstructionisdirectedtothebeach.
BeachdepositsareindicatedonFigureA.17.
FigureB.18DepositingConventionalTailings
ExtractionSand
Fines
Water
Recyclewater
MFT
Beach Beachabovewater
Beachbelowwater
Pond
MFT
Clearwater
Transition
-
B.8BasicTailingsfromExtractiontoMFT
TheRockDoctorB.8BasicTailingsfromExtractiontoMFTPage27
Beachabovewater
Thetailingsdischargeisspreadoverthebeachtopreventconcentratedflow.Smallstreamsflowoverthebeach.Theydeposit,erodeandredepositsandandmaterialcapturedinthevoids.Thatmakesthedepositinthebeachabovewaterhighlyvariable,rangingfromcleansandtosandwithvoidsfilledwithcapturedmaterial.
Beachbelowwater
Conditionsinthebeachbelowwaterarequieterthantheyareabovewater.
Intheunderwaterenvironmentgentleplacementcreatesloosedepositsformthatcantrapalotoffinegrainedmaterial.Theloosedepositsarepronetoliquefaction.SubmarinelandslidesandturbidityflowsarepartofthesystemthatdeliversmaterialdowntheslopeandintoadjacentdepositsofMFT.
ThevolumeandcharacterofsanddepositsisrelativelypredictableandissummarizedbyTableB.4.Thevolumeandcharacterofthefinetailingscomponentismuchmorecomplicated,partlybecauseinformationonclayanditsactivityisnotcollected.TableB.4Forecastpropertiesoftailingssanddeposits:
Deposit PorosityN
VoidRatioe
Weight%Solids%
DryDensityt/m3
BeachSlope%
Sandcompactedinacell 0.37 0.6 82% 1.67 Sanddepositedinabeachabovewater 0.40 0.68 80% 1.59 2%Sanddepositedinabeachbelowwater 0.43 0.75 78% 1.51 4%FinesformingMFTinthepond 0.86 6.2 30% 0.37
B.8.5Behaviourinthetailingspond
Thetailingspondisalargevesselthatclarifieswaterandprovidesstorageforfinegraineddeposits.
Materialthatentersthetailingspondconsistsofwater,unrecoveredbitumen,silt,clay,dissolvedchemicals,solventlosses,andprocessaids.
Thewasteslurryenteringthetailingspondisquitedilute,withatypicalsolidcontentof5to10%.Suspendedsolidsslowlysettleleavingclearwaterbehind.Asthesolidssettle,thesuspensionbecomesdenserandparticlesinterferewitheachother.Thistransitionzoneextendstoadepthofafewmetres.Finally,whenthedensityreachesabout30%solids,repulsiveforcesbetweenclayparticlespreventfurtherdensification.ThedepositatthatstageisknownasmaturefinetailsorMFT.
-
B.8BasicTailingsfromExtractiontoMFT
TheRockDoctorB.8BasicTailingsfromExtractiontoMFTPage28
AweaksoilstructureformsinMFTandrepresentsthestartofsoilstrength.Initiallythedepositisextremelyweak.ThelowstrengthinearlyMFTisindicatedbythefactthatindividualsandgrainsbreakthroughitandaccumulateatthebaseofthedeposit10sofmetresbelow.
Whensurfacewaterreachesasolidcontentof0.1%itcanberecycledtotheplant.(FineTailsFundamentalsConsortium(1995)pageIV74.)
Matsofbitumenalsoaccumulateintheponddeposits.
B.8.6Predictingthevolumeoftailings
Tailingspersonnelareresponsibleforforecastingthevolumeoftailingssostoragefacilitiescanbeconstructedandreadytostoreexpectedtailings.
Thevolumesofsanddepositsarepredictable,butthevolumeoffinetailingsisnot.ThevolumeofMFTisalargelyaresultofclay,andthewayitinteractswithwaterandthechemicalspresentinthewater.Extractionoperatorsdonotmeasuretheclaycontent.Theymeasurefinesthatcancontainfrom0%to100%claysizedmaterial.
Theaccuracyoftailingsforecastmodels,thatdonotconsidertheamountofclaypresent,ortheextentofclaydispersion,ishighlysuspect.OtherindicatorsoftheMFTvolumecanbederivedfromhistoricaldata.AtSyncrudetheaveragevolumeofMFTproducedpercubicmetreofaverageoreis0.266cubicmetres.
Atailingsforecastmodelwasdevelopedtoexploretrendsaffectingtailingsvolumes.FindingsaresummarizedinTableB.5below.AnelectroniccopyofthetailingsforecastmodelisinAppendixB.1.
TableB.5Highlightsofinformationobtainedfromthetailingsforecastmodel:
1. Oilsandextractioncreatestwotypesofwastedeposits:sanddepositsthataresolid,andfluidtailingsdepositsthatmustbecontained.Wastederivedfromaverageoreis75%sandand25%fluidtailings(MFT).
2. Foraverageorethevoidspaceinthesandisalmostequaltothevolumeoffluidtailings.3. Finescaptureinthevoidspaceofsandisimportant:
a. Finescapturedinthesanddisplacewaterandtherebyreducewaterloss.b. FinescapturedinthesandarenotavailabletomakeMFTinthepond.
4. Lowgrade(highfines)oreyieldslessbitumen,createsconsiderablymoreMFT,consumesmorewater,andresultsinhigherheatlossthanhighgradeore.
5. MethodsofreducingtheamountofMFTinclude:a. Reduceclaydispersionintheextractionprocess.
-
B.8BasicTailingsfromExtractiontoMFT
TheRockDoctorB.8BasicTailingsfromExtractiontoMFTPage29
b. Increasethedensityofthewasteslurrydischargedfromtheplant.c. IncreasethedensityofMFT.
6. Heatlossisproportionaltotheamountofhotwaterdischargedfromtheplant.Itcanbereducedbydensifyingthewastedischargestream(captureandrecycleprocesswaterwiththecontainedheat).
7. WaterlossequalstheamountofwatertrappedinsandvoidsandinMFT.Watersurplustothoseneedsisavailableforrecycletotheplant.Waterlosscanbereducedbydensifyingthedischargestream(notedin6above)andbyreducingthecreationofMFT(Item5above).
8. Themodelforecaststhatmostoftheunrecoveredbitumenwillconcentrateinthepond.Bitumenfollowswatertothepond,andthewateristhenrecycled.
9. IfMFTisdensifiedtoasolidstate,the%bitumenbyweightcouldriseto11%andthevolumeto17%.Iftailingsalsoincludesasphaltenes,theabovenumberscoulddouble.ThatsuggeststhatseriousconsiderationshouldbegiventorecoveringbitumenifMFTisreprocessed.
-
B.9TailingsDams
The Rock DoctorB.9TailingsDamsPage30
B.9TailingsDams
B.9.1Introductiontotailingsdams
Buildingcontainmentstructurestoholdfluidwasteisanimportantpartoftailingsmanagement.
Tailingsdykesaremassivestructures.TypicaldimensionsofthetailingsfacilitiesareshowninTableB.6
TableB.6Typicaldimensionsoftailingsdykes.
Height 50to100metresCrestwidth 50+metresSideslope 1:4withgoodfoundations
1:15overpoorfoundationssuchastheClearwaterFormationFootprint 1,500hectaresandabove
Thedykesprovidespacetostoresand,sodimensionscanbequitegenerous.Atthestartofaprojectwasteisplacedonsurfaceuntilthereisroomtoplaceitinpit.TableB.7showshighlightsofthesurfacepondproposedintheShellJackpineapplication(AlbianSands,2003).TableB.7HighightsoftheJackpinesurfacetailingspond.
Designlifeofactivephase 6yearsFootprint 1,600hectaresDykeheight 50mHoldingcapacity Fluidtailings 278millionm3 Beachedsand 171millionm3 Compacteddykes 115millionm3 Total 565millionm3
Dykesareoftenconstructedofsandusingtheconstructioncellsdescribedearlier.Sandaccumulatesintheconstructioncellandiscompactedbydozers.Finegrainedmaterialremainsinsuspensionandflowstothetailingspond.
FigureB.19showsatailingsdykeconstructedusingthecentrelinemethod.FigureB.20showstheupstreammethodofdykeconstruction.
-
B.9TailingsDams
The Rock DoctorB.9TailingsDamsPage31
Centrelineofdyke
EngineeredFill
Upstream Downstream
MFT
BeachedFillWaterCap
Nativesoilfoundation
FigureB.19.CrosssectionofatailingsdykeCentreline constructionmethod
Starterdyke
EngineeredFill
BeachedFillWaterCap
MFT
Nativegroundfoundation
StableBeachFoundation
UncertainBeachFoundation
FigureB.20CrosssectionofatailingsdykeUpstreamconstructionmethod
StarterDyke
Withcentrelineconstructionallmaterialdownstreamofthecentrelineisaccumulatedinconstructioncellsandcompacted.Materialplacedonthepondsideofthecentrelineispumpedontoabeach,butisnotcompacted.Materialthatisnotusedincellconstructionisdischargedontobeaches.
Withupstreamconstructiontheexternalfaceofthedykeisconstructedofcompactedcellsand.Sandplacedonthepondsideisbeachedbutnotcompacted.Asthedykegrowshigherthecompactedfaceshiftsupstream.Eventuallythatplacesitaboveuncompactedbeachsands.Theadvantageoftheupstreammethodisalowercostandapermanentexternalfacethatisreadytobereclaimed.Thedisadvantageisapotentiallypoorfoundation.Thereisariskthatsanddepositedunderwaterwill
-
B.9TailingsDams
The Rock DoctorB.9TailingsDamsPage32
experienceliquefaction.Inaddition,thepoorfoundationmaypreventraisingthedykeabovethedesignlevelinthefuture.Dykeraisingiscommonwithoilsandtailingsponds.
B.9.2Constructingwithoverburdeninsteadofsand Sometimesoverburdenorminewaste,insteadofsand,isusedtobuilddykes.FigureB.21Indicateschangesindesignthatarerequiredwhenoverburdenissubstitutedforsand.
MFT
Nativegroundfoundation
Compactedsanddyke
MFT
CompactedOverburdenDyke
Chimneydrain
Beachbufferzone
Nativegroundfoundation
FigureB.21CrosssectionoftailingsdykeChangeindykedesignifthereisashortageofsand
Nobeach
Watercap
Traditionalconstructionwithtailingssand
ChangeifsandisrequiredforCT
Constructionwithoverburdenismoreexpensivethanbuildingwithsand.Activitiesthataddtothecostofconstructingearthstructureswithoverburdenvs.sandaresummarisedinTableB.8.TableB.8Additionalcostsincurredwhenoverburdenisusedtobuilddykesinsteadofsand Earthdykesaremorecomplicatedthanthosebuiltofsand(Fig.B.21). Mustinspectandidentifysuitablematerialforconstructionattheborrowsource. Mustselectivelyloadconstructionmaterialfortransport.
Transportingtheselectmaterialtotheconstructionsiteinvolves:
extrahauldistanceand transportbytruckinsteadofbypipeline
-
B.9TailingsDams
The Rock DoctorB.9TailingsDamsPage33
Placematerialwhereneeded.Compactmaterial(probablybydriving400tontrucksoverit).Withnobeachtherewillnotbeanyfinescapture.ThatcouldincreasetheMFTby30%.
Theaddedcostoftheprecedingstepscouldbeafewdollarspercubicmetreofconstructionmaterial.
B.9.3Constructingretentionfacilitiesinpit.Dykesareneededtoseparatewastestoragefrommineoperationsinpit.FigureB.11.showedhowtailingsandminingworktogetheratSyncrude(Fair,2008).Notallwasteisfluid.FigureB.22illustratesthedifferenceinapproachusedtostorefluidwastevs.materialthatisstrongenoughtobeselfsupporting.
FluidWaste
Openminearea Dyke
OpenMineArea Stackable
solidwaste
Figure B.22Showingdifferentcontainmentrequirements
ToeBerm
-
B.10ProcessestodensifyMFT
The Rock DoctorB.10ProcessestodensifyMFTPage34
B.10ProcessestodensifyMFTAppendixB.4describesSoilPropertiesandBehaviour.Itsupplementsinformationprovidedinthischapterandisrecommendedreading.Thenovicemaywishtoreaditbeforereadingthischapter.
B.10.1DirecttreatmentprocessesMFTisaliquidthatwillrequireconfinementandsupportuntilitbecomesaselfsupportingsolid.FigureB.23summarizesthebehaviourofasuspendedsolidasthesolidcontentchanges.
FigureB.23Relativevolumesofmineralsolidandwaterinfluidtailings
DataplottedonFigureB.23Include
1. Thesolidcontentincreasesfromlowvalueswithliquidlikepropertiesatthetopofthepagetosolidmaterialwithstrengthatthebottomofthepage.
2. Horizontalbarsacrossthepagerepresenttherelativeamountofwaterandsolidcorrespondingtothesolidorwatercontentindicated.
-
B.10ProcessestodensifyMFT
The Rock DoctorB.10ProcessestodensifyMFTPage35
3. Themiddlecolumndescribesbehaviourofasettlingsolidasitprogressesfromaliquidtoasolid.
4. ThecolumnontherightdescribesmechanicalprocessesthatcanbeusedtodensifymaterialslikeMFTandindicatestherangeofeffectivenessofeach.
5. Thecolumnontheleftshowsnaturalprocessesthatdensifysuspensions.ItalsoindicatesthewatercontentofMFTandthetargetforsolidMFT.
Horizontalbarsrepresentthevoidratioofcorrespondingmaterial.Thevoidratioisdefinedasthevolumeofvoidsperunitvolumeofsolidmaterial.Thetopbarcorrespondstosuspendedsolidsenteringthetailingspond.Ithasasolidcontentof5%to10%andavoidratioof24.Thatmeans24volumesofwaterperunitvolumeofsoil.MFTisshown,withasolidcontentof30%andavoidratioof6.Thetargetmaterialforreclamationasasolidmaterialhasasolidcontentofabout30%andavoidratioofabout1.5.
B.10.2BehaviourasMFTdensifiesMiddlecolumnbehaviourThemiddlecolumndescribesthebehaviourasamaterialchangesfromadiluteslurrytoasolidstrongmaterial.Atthetopofthechartparticlesexperiencefreesettlinginwater.Thenextstateishinderedsettlingasparticlesbecomemorenumerousandinterferewitheachother.Finallyatabout30%solidssettlingstopsbecauserepulsiveforcesbetweenparticlespreventadenserpacking.30%solidscorrespondstoMFTwhereasoilskeletonandthebeginningsofstrengthdevelop.Withincreasingdensity,strengthdevelopsandthebehaviourprogressesfromliquid,toplastic,tosolidbehaviour.Theliquidlimitandplasticlimitsdefinethewatercontentbetweenthosezones.
B.10.3MechanicalprocessesThecolumnontherightofFigureB.23progressesfromgravitysettlingtomechanicalprocessesthatarelistedinorderofcapability.
-
B.10ProcessestodensifyMFT
The Rock DoctorB.10ProcessestodensifyMFTPage36
ThickeneroperationsThickeneroperationusuallyinvolvesdilutiontoabout10%solidtoseparatesuspendedparticlesinalargediametertank.Aflocculentisaddedtodrawtheparticlesintoagglomeratesthatbehaveaslargerparticles.Gentlestirringbyrakesatthebaseofthethickener,sometimesaidedbysandaddition,andbytheweightofoverlyingmaterialforcingflockedmaterialtotheoutletinaconicalbaseaiddensification.Thenormalprocessingyieldsadensityofabout30%solids.Higherdensitiesarereportedbutmaybeduetotheadditionofsand.AsnotedinSection4.1ofAppendixB.4,addingsandaddstomassandtovolumebutnottostrengthatlowsandtofinesratios.Thetypicalresidencetimeinathickenerishalfanhour.IttakesafewyearstoachievethesamedensityinatailingspondTheadvantageofthethickeneristhatitrecoversprocesswater,withitscontainedheat,thatcanthenberecycledandreused.Anotheradvantageofthethickeneristhatitdensifiestheplantstailingsoutletstream.Thatenhancesfinescaptureinsanddeposits.ThecapturedfinesarenotavailabletomakeMFT.Superflocculatingagentsmayachievehigherdensitiesbutareapproachedwithcautionincasethepresenceofthesuperflocinreturnwateradverselyaffectsextraction.(Gu,2009).FilterbeltAfilterbeltisaporousbelt.Inoperationasandblanketisplacedonthebelt.Thenfinesaretreatedwithacoagulantandplacedontopofthesandblanket.Thecoagulantreleaseswaterfromthefines.Suctionappliedtothebottomofthebeltremoveswaterfromthematerialbeingtreated.Thesuctionforceisnotgreatbutitonlyhastoactonanarrowthicknessofmaterial.Filterbeltshavebeenproposed(FineTailsConsortium1995e)buthavenotbeenusedincommercialoilsandprocessing.Concerns:verylargeareasofbeltarerequiredtoprocesslargetonnagesoffines.Inaddition,bitumenfromextractioncouldeasilyclogthebelt.FilterpressAfilterpressexertsahighmechanicalforceonasmallareatocompresssolidsandforcefluidfromthem.Theyarerelativelysmallunitssohavenotbeenusedinoilsandprocessing.CentrifugetreatmentCentrifugesapplythousandsoftimestheforceofgravitytoextractfluidfrommaterial.Theoutletstreamsyieldssolidsatadensityofabout60%.Theotherstreamyieldswater,bitumen,andaminoramountoffines.
-
B.10ProcessestodensifyMFT
The Rock DoctorB.10ProcessestodensifyMFTPage37
Centrifugesareusedextensivelyinoilsandfrothtreatment.TheyhavenotbeenusedcommerciallytoprocessMFT.Centrifugeshavebeensuccessfullypilotedindemonstrationplants(Fair,2008)(Loganet.al.1984).However,testingatfullscaleisneededtoproperlyevaluatethepotentialofthistechnology.BruteforceheatingThehighestlevelofmanmadedensificationinvolvesbruteforceheating.Itistooenergyintensiveandexpensivetoconsider.Theprecedingtechnologiesofferaprogressiveapproachtodewateringfines.Twocautions:
Sandadditioncanaddtodensitywithoutaffectingstrengthandneedstobeunderstood. Chemicalaidscanlowertheliquidlimit,andinturnchangesolidcontentatthetargetstrength.
B.10.4Naturalprocesses.TheleftcolumnofFigureB.23showsnaturalprocessesthatdensifyfines.SedimentationDilutesuspensionsaredensifiedbynaturalsettlementandsedimentation.Asettlingparticlepassesfromadilutesuspensionwhereitisunaffectedbyneighbours,toatransitionzonewhereotherparticleshindersettlement.Whenthedensityreaches30%solidsinterferenceandrepulsiveforcesbetweenparticleshaltfurthersedimentation.ThatmaterialisknownasmaturefinetailsorMFT.ConsolidationConsolidationprocessesaredescribedinSection6ofAppendixB.4.CurrentmethodsofplacingMFTdonotaidconsolidation.Itisnotlikelytoworkintimeunlesssupplementedbywickdrains.SuctionprocessesNaturalprocessesarecapableofexertingsuctiontodensifyadepositofMFT.Underidealconditions,suctionashighas10atmospherescanbeexertedthroughdrying,hydroponics,freezethaw,orbyaddingdryswellingclay.Applicationofsuchlargeforcesisenoughtocompressafinegrainedsoiltoadense,strongstate.Dryingtreatmentinvolvesremovingsurfacewaterandlettingtheexposedsoliddryout.Thetreatmentisasurfacephenomenonsoonlythinlayers(e.g.20cmthick)canbetreatedandrepeatedthroughthe
-
B.10ProcessestodensifyMFT
The Rock DoctorB.10ProcessestodensifyMFTPage38
summer.Thesiteisslopedtofacilitatesurfacedrainage.Largeareasarerequiredtotreatlargequantities.Hydroponicsinvolveusingplantstoexertsuctiononadepositoffines.TheplantscanprocessadeeperprofileofmaterialbutarestilllimitedbythinsurfaceeffectsandtheverylimitedgrowingseasoninFortMcMurray.Whenasoilfreezeswaterisattractedtothefreezingfrontwherepureiceforms.Thesuctionexertedoverloadsandcollapsessoilstructure.Whenthematerialthaws,icemeltsandthewaterisdrainedoffbeforeitcanbereassimilatedinthesoil.Asignificantthicknessofmaterialcanbetreatedbyfreeze/thawiftheprocessesisrepeatedontopofapreviouslyfrozenlayer.Thelimitofhowmuchcanbetreatedperyearisprobablyrelatedtohowmuchcanbethawedthefollowingsummerseveralmetres.Dryswellingclaywouldliketoabsorbmoremoisture.IfblendedwithMFTitwillextractwateruntilthewatercontentofthetwomaterialsreachesastateofequilibrium.Thedryingcapabilityofthistechniqueisquitehigh,anddryswellingclaysareabundantinoverburdeninthemineableoilsandsarea.Thisprocessisnotasurfacephenomenonsocanbeappliedtoanythicknessofmaterial.Themainapplicationfordensificationbyblendingwithswellingclaymayberemovingthelastbitofwaterrequiredtomeetstrengthtargets.Theprecedinglistshowsmechanicalandnaturalprocessesthatcandensifyfines.Itisunlikelythatmechanicalprocessesalonewillbeabletoachievethedensitydesiredforsolidwaste.Naturalprocesseswillhavetobeusedasthefinishingprocess.Thesodiumadsorptionrationofmaterialproposedfortreatmentbysuctionbasedprocessesthatrelyonnaturalwaterrunoff.(seeAppendixB.4).Soilswithahighsodiumadsorptionratioarehighlyerosivesowilltendtoberemovedbyrunoffwater.ItisunlikelythattherewillbeoneSilverBullettomeetalldensificationneeds.Itismorelikelythataprogressionofprocessesshouldbeusedwitheachworkinginthezoneinwhichtheyaremosteffective.
B.10.5MixturesPasteandCT
-
B.10ProcessestodensifyMFT
The Rock DoctorB.10ProcessestodensifyMFTPage39
ThissectiondescribedcombinedprocessesthatareusedtodensifyMFT
Pasteisablendofcoarseandfinegrainedtailingsmaterial.Pasteisnonsegregatingoverarangeofmixesandthatpropertyisusedtoadvantageintransportation,depositionandconsolidationoftailings.
Theuseofnonsegregatingmixesischangingtailingspractice.CTisanonsegregatingmixandisdescribedbelow.
TheCTprocesswasdevelopedattheUniversityofAlbertainthelate1980s(Caughilletal.,1993).Itmeetstheminersdreamofcreatingaproductthatcanbepumpedtothedisposalsite.AtthedisposalsiteCTreleasessurpluswaterandconsolidatestoasolidstatesuitableforreclamation.Atleastthatswhatoperatorshopewillhappen.
SomeoperatorsusevariationsofCTandcallitNonSegregatingTailsorNST.Theprocessesaresimilar.
CTiscreatedandusedasfollows:
MFTistreatedwithacoagulant(gypsum)andthenblendedwithsand. Theblendcreatesanonsegregatingmixforsandtofinesratiosovertherangeof3to6. Theresultingslurryisanonsegregatingblendthatcanbepumpedtoitsdisposalsite, Atthedisposalsiteitflowstoitsfinalrestingplace,againwithoutsegregating, Inplacethedepositslowlyreleasesexcesswater.Initiallyitreleasesexcesswater,andthen
waterreleasedbyconsolidation.
Afivemetersurchargeofsandisappliedatsurfacetoaccelerateconsolidationandtoprovidedesiredstrengthintheupperlayers.
Intime,thedepositconsolidatestoastrong,selfsupportingsolid.
TableB.9showstherelativevolumesassociatedwithCTmanufacture.
TableB.9RelativevolumesintheCTmakingprocess
Parameter Volumem3
SolidContent
Sand/finesratio
Timetoconsolidate
MFT 1.00 30%
Sand 1.27 72%
CTslurry 2.27 57% 4.5
CTdeposit 1.27 80% 4.5
Waterrelease 1.0
Estimatedtimetoconsolidate
4.0 10years
-
B.10ProcessestodensifyMFT
The Rock DoctorB.10ProcessestodensifyMFTPage40
Estimatedtimetoconsolidate
5.0 5years
CTdepositsarefluidsorequirecontainmentforseveralyearsuntiltheyconsolidatetobecomesolidselfsupportingdeposits.
DespitemanyyearsofcommercialusethathasproducedtensofmillioncubicmetresofCTtheprocessisstillunderreview.Apparentlyoperatorshaveexperienceddifficultymaking,transportingandplacingonspecCT.AccordingtoHoulihanet.al.(2008),after10yearsofcommercialuse,Suncoronlyachieved20%ofplannedproductionin2005.
TheCTprocessisanimportantpartofmanycommercialapplications.However,thereisaseverelackofpublicinformationabouttheresearchbehindtheconcept,howitissupposedtowork,thetargetstrengthforprocessedmaterial,operatingperformance,whatsuccessindicatorsarebeingused,andtheprobabilityofsuccess.
AzamandScott,(2005),developedaTernaryDiagramtomapthebehaviourboundariesofanonsegregatingmix.Itisathreedimensionalplotofsand,finesandwatercomponentsillustratedonFigureB.24.
-
B.10ProcessestodensifyMFT
The Rock DoctorB.10ProcessestodensifyMFTPage41
BoundariesthatcanbemappedontheTernarydiagraminclude:
Thesandmatrix, Thefinesmatrix, Wheresedimentationoccurs, D=segregatingvs.nonsegregatingmixes, Pumpablevs.nonpumpablemixes, Saturatedvs.nonsaturatedmixes.
ForCTmanufacturetheboundaryofgreatestinterestistheboundarybetweensegregatingandnonsegregatingmixes.Thatdefinesasmixofmaterialsthatcanbepumped,depositedandallowedtoconsolidate.TheTernaryDiagrammaybeanoversimplificationofmaterialproperties.Anewchartisneededwhenevertheclaycontentorclayactivitychangesinthefinesrepresented.TableB.10summarizesconcernswiththeCTprocessingoption.TableB.10ConcernswiththeCTprocessingoption
Demandexceedssandsupplyo Thedesiredsandtofinesmixis4and5.o Thesandtofinesmixoforeaveragesbetween4and5.o Anoperatingefficiencyof100%wouldberequiredtoprocessallMFT.o AsupplementalsourceofsandwillbeneededtotreatthestrandedMFTinventoryor
Requireanotherprocesstofinishthejob. CTrequirescontainmentuntilitconsolidates.Containmentisexpensive. AttemptstoassignallsandtoCTproductionarecounterproductive
o Requiresdykeconstructionwithoverburdenmuchmoreexpensiveo LosebenefitoffinescaptureinsandthatmayincreaseMFTmakeby30%o Losesafetyfeaturesthatbeachesaddtoretainingstructures.
CTperformanceafter10yearsofcommercialoperationhasnotbeendisclosed. Sulphateadditionmaybefoodforbacterialactionundesirable. Concernsthatthetreatmentisreversiblehavenotbeenansweredinpublic.
-
B.11StoringMFTunderawatercap
The Rock DoctorB.11StoringMFTunderawatercapPage42
B.11StoringMFTunderawatercap
B.11.1 Permanentstorageunderawatercap
In1992SyncrudeproposedtosolidifyMFTusingCTtechnologyandtopermanentlystoresurplusfluidtailingsunderawatercap.
Severalearlypapersdescribetheconceptandstudiesundertakentoconfirmitssuitability.(Nixetal,1988),(Boergeretal,1990),(MacKinnonetal,1991),(Boergeretal,1992),(Gullyetal,1993),(MacKinnonetal.,1995),Thepapersarefoundindiversepublications.Mostoftheauthorsarecloselyrelatedtoprojectsthatstandtobenefitfromthepractice.
AkeyrequirementnotedintheearlypapersisthatthereshouldbenomixingbetweentheMFTandtheoverlyingwatercap.Thepapersexploredpossiblemixingbytheactionofsurfacewaves,andthedesigndepthofthewatercapwassettoat9metrestopreventsuchmixing.Theresearchersconcludedthatgasevolutionfrombiologicalactivitywasunlikely!Inthemid1990smethaneproducingbacteriabecameactiveinSyncrudesMildredLakeBasinandvigorousbubblinghasbeenongoingsince.Limitedresearchrecognizethebacterialactivityandnotethatitcouldaffecttheviabilityofthepermanentstoragescheme.(Holowenko,2000),(Li,2008).Differentbacteriaareactive,consumingdifferentfood(naphtha(solventloss),sulphate(usedinCT),andsodiumcitrate(addedatAlbianSandstoaidextraction).Theauthorwasunabletolocatepublicationsthatshowwhygasreleasefrombacterialactionshouldnotbeaconcern.SyncrudeshowedtheviabilityofstoringMFTunderawatercapinsmallpits.Thedemonstrationpitsprecededbiologicalactivity.AfullscaletestisplannedintheSyncrudebaseminelakestartingin2012.TheexperimentwillinvolveplacingprocessaffectedwaterontopofMFTandobservingbehaviouroverthenextdecade.Furtherdetailshavenotbeendisclosed.Themostrecentpublicationontheendpitlakeconceptprovidesanupdateontheconceptandresearch(ClearwaterConsultants,2007).ThepaperquotedSyncrudereferencesextensively.Itnotesthatitmaybedecadesorlongerbeforetheendpitlakewillqualifyforareclamationcertificate.Itdidnotevenmentionbiologicalactivityorstandardsthatgovernsafelocationsforperpetualstorageoffluidwaste.Thosefactorsreallyneedtobeaddressed.OneaspectofasuggestedguidelineforsafesitesforpermanentstorageoffluidtailingsisprovidedinFigureB.25.
-
B.11StoringMFTunderawatercap
The Rock DoctorB.11StoringMFTunderawatercapPage43
Sethisuggeststhatthatongoingbubblingrepresentsastateofflux.Hesuggeststhatbacteriashouldbeputintoadormantstate.(Sethi,2009).
FigB.25Suggestedoffsettoprotectagainstlongtermgullyexposure
BaseLevel 1o
Containment
Reclaimedcap
WeakTailings
Protectedzone
Vulnerablezone
Challenges:
1. Thereisnopublicdocumentationoncriteriaforasafesurfacestoragesitetoholdcontaminatedfluidinperpetuity.Twosuggestionsforsiteselection:
a. Mustnotbelocatedonasitewheregroundwatercoulddischargeatsurface.MostlocationsneartheAthabascaRiverarepotentialgroundwaterdischargesites.
2. Thesiteshouldbesafefromfutureexposurebyerodinggullies.AsuggestedsafegeometryIndicatedonFigureB.25.FluidshouldnotbestoredabovealineslopingupwardfromanadjacentstreamorfromtheAthabascaRiverbaselevel.Theinclinationoftheslopinglineshouldbesetbequalifiedprofessionals(geographers,engineeringgeologists)andtheirviewofthepotentialforlongtermgulleyerosion.Theauthorsuggeststhatinsandysoiltheexpectedslopeshouldbe1%orless.
3. Thereislimitedpublicpeerrevieweddocumentationdiscussingtheconcept,ofrecentverificationprograms,orofcontingencyplans.
-
B.11StoringMFTunderawatercap
The Rock DoctorB.11StoringMFTunderawatercapPage44
4. Biologicalactivityinthefluidtailingsemitsconsiderablegascapableofmixingfluidtailingswithoverlyingwater.Littleifanypublicdisclosureoffieldperformanceandwhydevelopersconsiderthistonotbeaproblem.Canweevenpredictfutureperformanceaslongasgasemissionsareongoing?
5. Waterreleasefromconsolidationhasbeentakingplacefor40years.Ithasapparentlyincreasedbyordersofmagnitudesincethebiologicalreleaseofgasesshortenedthedrainagepathforreleaseofconsolidationwater.Thereislittleifanypublicinformationontherateoffluidemissionsfromfluidtailings.
6. In1992SyncrudeproposedtosolidifyMFTusingCT.Sincethentheyhaveonlytreated10%oftheMFTcreated.Whathappenedtotheoriginalpromise?
7. RegulatorshavenotapprovedpermanentstorageofMFTunderawatercap.Insteadtheyhaveadvocatedasolidtrafficablelandscapeinstead(Houlihanetal,2008)
8. Thereisnopublicinformationonhowfinancialassuranceisbeingprovidedtoensurethatstrandedfluidtailingswillbesatisfactorilydealtwith.ThetopicrequiresdisclosurebecausethelargestownerofSyncrudeisaTrustwithnoothersourceofincometofundreclamationobligations.
B.11.2EndpitlakeAttheendofoperationsthelastmineopeningwillbeusedasanendpitlake.Runofffromsitesurfaceandgroundwaterwillbedirectedtotheendpitlake.Accumulatedwaterwillbemonitoredforquality,priortodischarge.OperatorsalsoplantopermanentlystoreMFTinthebaseoftheendpitlake.
Itcouldbeseveraldecadesbeforethewaterintheendpitlakewillbereadyforrelease.(ClearwaterConsultants,2007).
Thereislittlepublicinformationabouttheendpitlakes.Keyconcerns:
Whenwilltheconceptbesharedwithpublicstakeholders. Whatistheexpectedquantityandqualityofwaterthatwillenterthelakes. Whatstoragecapacitywillberequiredtoholdrunoffuntilwatercanbedischarged?Creating
storagetohandledecadesofrunoffaforecastbyClearwaterConsultantscouldbeaseriouschallenge.
Arethereplanstotreatwateriftheendpitlakesdonotselfcleanse? Whatarethecontingencyplans? Howdowefundclosureoperationsandcontingencyplansthatwilltakeplacedecadesafterthe
Operationsandincomeareover.
Theendpitlakeproposalappearstobeahighriskoption.AddingMFTstoragetothebaseofthelakeaddsanunnecessarycomplication.
-
B.12Worldtailingspracticesandimage
The Rock DoctorB.12WorldtailingspracticesandimagePage45
B.12Worldwidetailingsmanagementpractices.
Itisinstructivetoexplorehowtheworldwideminingmanagestailings.
ThekeynoteaddressatPaste08,anannualinternationalminetailingsconference,presentsanunflatteringsummaryofcurrentinternationaltailingsmanagement.(Bogeret.al.,2008).Highlightsofthekeynoteaddressfollow:
Themineralsindustryistheworld'slargestproducerofwaste. Therehavebeensignificantimprovementsinthickeninganddewateringtailingsthatofferand
potentialsavingsinreclamationandenvironmentalmanagementcosts. However,anemphasisonexpendituredeferralpromoteslowcapitaltailingsdisposalsolutions. Tailingsstoragefacilitiesallowwastestorageforalongperiodoftimewhiledeferring
expenditureonreclamationuntiltheendofmining. Alargepartoftheindustrystillcontinuestopumplowdensitymaterialtoverylargedisposal
dams.Thedamsgetbiggerandbiggerandrepresentasignificantrisk.Theyalsorepresentasignificantcostwhenthetimecomestoreclaimthem.
Concernswithtailingsdamsincludeatendencytoleakandapotentialforcatastrophicfailure.Twostandardsgovernfinancialreportingrequirements:"USbasedFinancialAccounting
Standard143:AccountingforAssetretirementObligations(SFAS143)andtheInternationalAccountingStandard37:Provisions,ContingentliabilitiesandContingentAssets(IAS37).Bothstandardsrequirethatreclamationliabilitiesberecognizedonthebalancesheetassoonastheliabilityisincurred,andfortheamounttobediscounted.InadditionSFAS'43requirestheestimatebeincreasedbythetheoreticalcostofsettlingtheliabilitywithathirdpartyinordertoestablishamarketvaluefortheliability.
o Generallyfuturereclamationliabilitiesarecomputedasfollows:o Thefuturecostofreclamationisdeterminedbyinflatingcurrentcoststothefuturedate
whenreclamationmightoccur.o Thefuturecostisthendiscountedbacktotodaybyapplyingasignificantdiscountrate
eachyear.o Discounting,overthelongtimeframetypicalofminingventures,reducesthe
reclamationliabilitytoanegligibleamount.o Discountingisasystematicbiastowardshorttermprofitability.o Historically,industrywideenvironmentalimprovementshavebeenachievedthrough
mandatingrequirementsviaregulation."
TableB.11summarizessomesideeffectsofdiscountingoverlongperiodsoftime.
-
B.12Worldtailingspracticesandimage
The Rock DoctorB.12WorldtailingspracticesandimagePage46
TableB.11Effectofdiscountingoverlongperiodsoftime.
Discountingseverelyreducestheapparentcostoffuturereclamationliabilities;Discountingjustifiesdeferringreclamationandmaximizingshorttermprofits;Reducingthecostoffuturereclamationliabilities:
o Reducestheneedtosetfundsasidetomeetfutureobligations,o Reducestheneedtoverifythefeasibilityofreclamationandclosureplans,o Reducestheincentiveforresearchtofindabetterapproach,o Createsfalseshorttermprofitsthatrewardthosewhomanagethediscountdeception.
Buildinglargeinventoriesoffluidtailingscreatesriskof:o Accumulatinglargerandlargerliabilitiesthatwillhavetobedealtwithinfuture,o Increasesriskofseepageorcatastrophicfailure,o Thedeveloperbeingunabletopayforthereclamation,o Accumulatedliabilitiescauseaprematurehalttooperationsiftheyexceedfuturevalue,o Untestedreclamationplansmaynotbefeasible.
ThecurrentapproachiscontrarytotwounderlyingprinciplesoftheAPEAAct(Alberta,1993): FailuretodisclosereclamationtechnologyandplanspreventsAlbertansfromproviding
inputtoreclamationdecisions. Deferredreclamationtransfersreclamationliabilitiestofuturegenerations.
Theprecedingactionsarenotwhatthepublicexpectsofresponsiblemanagement.TableB.12summarizessideeffectsofbookingreclamationastheyoccur.TableB.12EffectofbookingreclamationliabilitiestheyoccurbyfundingaQET.
PlacingfundsofequivalentvalueinaQualifyingEnvironmentalTrust:o Recognizesreclamationliabilitiesastheyoccuro Discountingcannotreducethevalueoftheliabilityo Theproceduresetsfundsasidetopayforfuturereclamationactivities.Itdoesnottransfer
liabilitiestofuturegenerations.o Reducesthedeveloperscostofreclamation.QETfundingisanoperatingexpensethat
triggersfiscalsharing.Inthehighlytaxedoilsandsindustrythataverages50%.o Createsanincentiveforprogressivereclamationasithasbeenpaidfor.o Progressivereclamationreducesstockpiledtailingswiththeassociatedrisks.o Progressivereclamationreducestheneedforfinancialassurance.
Withthevalueoftheliabilityretained:o Thereisastrongincentivetoverifyreclamationandclosureplansandtheircosts.o Thereisanincentivetoinvestinresearchtoimprovereclamationandclosureplans.
TheprecedingactionsarecompatiblewiththeintentionsoftheAEPEAAct. Theprecedingactionsarecompatiblewithpublicexpectationsofresponsiblemanagement.
OilsandindustryoperatorscouldimprovetheirimagebyadoptingtheconceptsbehindTableB.12.
-
B.13Screeningtechnologyoptions
The Rock DoctorB.13ScreeningTechnologyOptions Page47
B.13.1IntroductionThissectionexploreswhatisinvolvedinscreeningtailingstechnologies.Topicsinclude:
Characteristicsofmineableoilsandprojects Typicalstepsinvolvedinscreeningtechnologyoptions Typicalapproachestoeconomicanalysisandtheimplicationstothescreeningprocess Examples Conclusionsandrecommendations AboutQualifyingEnvironmentalTrusts Assigningcoststofuturereclamationobligations
B.13.2CharacteristicsofoilsandprojectsMineableoilsandprojectshaveuniquecharacteristicsthataffecttheappropriateapproachtoeconomicscreening.TableB.13summarizessomeimportantcharacteristicsofoilsandprojects.TableB.14showsthetimelineforsiteuse.TableB.13CharacteristicsofmineableOilSandProjects Largesize, Longprojectlife(upto100years), Largereclamationliabilitieslinkedtoproduction:
- Landdisturbance,- Fluidtailings,- Closurecosts.
Longtimebetweenwhenareclamationliabilityiscreatedandwhenitisdealtwith:- Fluidtailingscurrently25to40+years,- Landreclamationcurrently30to40+years,- Closureactivities50to100years.
Complex fiscal terms that involve capital cost allowances, Alberta royalty, Alberta and Federalincometax,andfiscalsharingofprofitsandexpenditures.Afterpayout,between45%and56%ofprofitandexpensesisdirectedtogovernments,
Ahighproject rateof return isneeded to justify the initial investment and to support the fiscalterms.
TableB.14Typicaltimelineforsiteuse
Year Landuse02 Sitepreparation220 Openpitmine2030 Siteoccupiedbytailingspond
-
B.13Screeningtechnologyoptions
The Rock DoctorB.13ScreeningTechnologyOptions Page48
3040 Solidifytailings4050 Reclaimsurface100 Siteclosure
InformationinTables1and2wasderivedfromFair,(2008);Syncrude,(2006);andSyncrude,(2007).Itshowsthatreclamationoftailingsanddisturbed landscanbedelayedby20to50years.Italsoshowsthatclosureactivitiescanbedelayedbyupto100years.
B.13.3.Stepsusedtoscreentechnologyoptions StepsinscreeningtailingstechnologiesareoutlinedinTableB.15.
TableB.15Typicalstepstoscreentechnologyoptions.1. Establishgoalsfortheprojecte.g.
Reclaimtailingsasasolidlandscape. Qualifyforareclamationcertificatewithinafewdecadesafteroperationscease.
2. Identifycandidateoptionsthatwillachievethosegoals.3. Foreachoption:
a. Identifyplanstousetheoptionthroughdevelopment,operationsandclosure.b. Identify full lifecycle capital and operating costs associated with the above. (If we are
comparingoptionsweonlyneedtoidentifycostdifferences.)c. Conductaneconomicassessment.d. Appraisetheprobabilityofsuccess.
4. Choosetheoptionthatwillmosteconomicallymeetprojectgoals.Projectsspendconsiderableeffortexploringtheviabilityofdifferenttechnologiesandtheprobablecostvs.time.Equivalenteffortshouldbespentevaluatingtheeconomicevaluationprocessbecause itcanhaveamajoreffectontheoutcomeofscreeningstudies.
B.13.4CharacteristicsofeconomicanalysisEconomicevaluationsappraisethecashflowoverthelifeofaproject.Theyconvertfutureexpendituresto today by applying discounts. All economic evaluations apply some form of discounting to futureincomeorexpenditurestoconvertthemtopresentvalue.FigureB.26shows theeffectofdiscounting todetermine thepresentvalueof futureobligations.Theplotshowsarapiddropinvaluewithtime.Lossisgreatestwhenhighdiscountratessuchas20%or30%areappliedoverlongperiodsoftime.Theyreducethevalueoffutureobligationstonearzeroin20to30years.TraditionaleconomicevaluationoftailingsoptionswouldcombinethetrendsofFigureB.26(effectofhigh discount rates)with the trends of Table B.13 (long time spans). The combination significantly
-
B.13Screeningtechnologyoptions
The Rock DoctorB.13ScreeningTechnologyOptions Page49
reducesoreliminatesfutureexpenditureobligations.Thatmeansthatdecisionsaboutthesuitabilityoftailingsoptionsaremadewithoutconsiderationoffutureexpenditureobligations.
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1 11 21 31 41 51 61 71 81 91
Residu
alvalue
%
Timeinyears
FigureB.26EffectofDiscountFactorandTime
30%Discount
20%Discount
10%Discount
5%Discount
2%Discount
TableB.16liststhreeapproachestoeconomicscreeningthatwereusedtoevaluatetailingsoptionsinPartAofthisreport.TableB.16Threeeconomicscreeningmethodsusedtoevaluateoilsandtailingsoptions.
1. Comparetheundiscountedcostdifferencesvs.timeforeachoption.2. Comparetheundiscountedcostdifferencesvs.timeconsidering:
a. Costvs.timeasinmethod1above.b. Recognizethevalueofreclamationobligationsastheyarecreated.c. Deposit an amount equivalent to the reclamation liability as it is created in a Qualifying
Environmental Trust as reclamation liabilities are incurred. Funds can be withdrawn asreclamationisundertaken.
3. Finally, compare leading contenders in a project economic model that duplicates the projectfinancial environment. Themodel considers all applicable fiscal terms such as Alberta royalty,capitalcostallowances,andincometax.
Netpresentvaluecomparisons isoftenused insteadofundiscountedcosts.Netpresentvalueanalysisappliesdiscounting.AsFigureB.26showsdiscountingoverlongperiodsoftimedistortsanddiminishes.thevalueoftheparameterunderstudy.Discountingdoesnotreducefutureobligations ifmethod2.caboveisused.PlacingfundsinaQualifyingenvironmentalTrustretainsthevalueofthereclamation.
-
B.13Screeningtechnologyoptions
The Rock DoctorB.13ScreeningTechnologyOptions Page50
Method three is required to verify that the conclusions of simple screening test still apply to thecomplexfiscalenvironmentthatappliestooilsandsprojects.AppendixB.1 contains electronicmodels that allowuser input to evaluate technology andoperatingoptions.Modelsandspreadsheetsinclude: A spread sheet for each tailings technology studied in Report A. Information includes material
balances, siteactivity,work, capitalandoperating costsvs time foreach technology.Capitalandoperatingcostsaresuggestedbuttheusercaninputtheirownvalueforcapitalandoperatingcostsifdesired.Technologiesarerankedbycomparingtheunitcostofprocessingonecubicmetreofore.
A fullprojecteconomicmodel isprovided. Itaddresses royalty,capitalallowances,provincialandfederal income tax to represent thecomplex fiscalenvironment thatoilsandprojectsoperate in.Tailings technologiesare comparedbyentering technology specific capitalandoperatingcostsvstimeinthemodelwhileotheraspectsofthebusinessareheldconstant.Comparisonoftheoverallproject rateof return foreach technology indicateseconomicperformance. Inputparametersaresuggestedbutthemodelallowsuserstoinputtheirowndataifdesired.
Atailingsforecastmodelisprovided.Itallowsuserdefinedinputtoevaluatetheeffectofdifferentmaterialoroperatingparametersontailingsoutput.
Themodelsandspreadsheetsshowtrends.Theyareprovidedtohelptheuserunderstandtherationaleused toappraise thedifferent tailings technologies.Themodelsshouldalsohelp theuserunderstandthemanyinteractionsinvolvedinevaluatingtailingsperformance.
1.
B.13.5ResultsofscreeningstudiesScreeningtailingstechnologiesFigures A.19 and A.20 from Section A of this report are repeated below. They show the effect ofscreeningcostdifferencesusingundiscountedunitcosts.Netpresentvaluecomparisonyieldsthesametrendsifmethod2.CofTableB.16isused(fundaqualifyingenvironmentaltrust)
-
B.13Screeningtechnologyoptions
The Rock DoctorB.13ScreeningTechnologyOptions Page51
$
$0.50
$1.00
$1.50
$2.00
$2.50
$3.00
$3.50
$4.00
Base T1 T2 CT2 Cent
Unitcostp
ercub
icm
etre
ofA
verage
Ore
FigureA.19CostDifferencesBetweenTailingsTechnologiesComparescostsforcapital,operations,relatedtoearthwork,
tailingsandheatloss.
HeatLossCosts
TailingsCosts
EarthCosts
OperatingCost
CapitalCost
BaseCase=conventionaloilsandsplantthatmakesMFTT1 ThickenerwithoutcyclonesT2 Thickenerwithcyclones
CT2 CTPlantprocessingoreandfinesderivedfrom theoreprocessedCent=inplantcentrifugecreating"solidwaste"
Figure A.19 compares undiscounted unit cost for the different tailings technologies. Environmentalcostsarenot includedbecausetraditionaleconomicanalysisdiscountsthemthetrivialamounts.Thismethodfavoursoptionsonthe leftthatpostponespending,stockpilefluidtailings,and insodoing,transferenvironmentalobligations to futuregenerations.The favoured technologiesdonotpreparetheprojectforclosure.
$
$0.50
$1.00
$1.50
$2.00
$2.50
$3.00
$3.50
$4.00
Base T1 T2 CT2 Cent
Unitcostp
ercub
icm
etre
of"Average"Ore
FigureA.20CostDifferencesBetweenTailingsTechnologiesConsiderskeylifecyclecosts
ClosureFund
WaterTreatmentFund
MFTReclamation
LandReclamation
HeatLossCost
TailingsCost
EarthCost
OperatingCost
CapitalCost
BaseCase=conventionaloilsandsplantthatmakesMFTT1=ThickenerwithoutcyclonesT2 Thickener withcyclones
CT2 CTPlantprocessingoreandfinesderivedfromoreprocessedCent=inplantcentrifugecreatingsolidwaste
-
B.13Screeningtechnologyoptions
The Rock DoctorB.13ScreeningTechnologyOptions Page52
FigureA.20comparesundiscountedaverageunitcoststhatrecognizereclama