FRAGMENTATION&BLOCKCAVEDRAWFragmentationEquipmentselectionRockhandlingstrategiesDrawpointproduction(mm/day/draw/caveheight)BCFPrimary(Backrockblocks-inputsjointdist,stress,RMR)Secondary(backrockblockscrushbycavemuckpile)Hang-upprogramme(drawpointblockagefreqordrawntons)Equipment/strategiesrealtiestodrawpointblocksizesDrawproduction=drawpointareaxdrawpointtonnage/ratesFragmentationOtherusesDrawpointsizes/spacingDilutionentryExperiencelevelsofstaffFragmentationPrimaryfragmentationSecondaryfragmentation/brokenbymuckpileweightPrimaryfragmentationPanelcave(Massmin92)Muckpilemodel(Bartlett1997)FragmentationDeterminationEmpiricaltables(Laubscher2000)

-Primary -Secondary -effectsBCF(Esterhuizen1994) -Primarysecondary -Secondary -Drawratesandhang-upfrequencyCHASM(Butcher2000) -Primaryfragmentation -VisualizationtoolJKFrag(Harries2001) -Primary -RigoroustoolMethodusesDesktop–Experience,EmpiricalBCF,ScopingwithgeneraldataCHaSM,JKFRAG,moreBCFabovescopingMethodlimitationsChaSM,-LABOURIOUS,PRIMARYFRAGONLYBCF,JointstatsmaycauseerrorsinblockformationEmpirical.limitedtoauthorsexperienceJKFRAG,ResearchtoolAllaremodelsFragmentationinputdataPrimary

-Meandip/dipdirection -Spacingstatistics -Rockmassstrength -Dip/directionofthecaveface -Generalstressregime

SecondaryAspectratioRateofdrawCushing/finesCaveheightandmuckpilepressure

Jointinputdata(Stacey&Swart2000)ChaSMFragmentation(BCF)Fragmentation(BCF)EquipmentselectionM3%passingfragmentationcriterion%>2or3m3:>2m3(4.6m3LHDbucket-1400E)>3m3(6.4m3LHDbucket-0010)PrimaryFrag>2m3=40%SecondaryFrag>2m3=15%RockhandlingstrategiesDrawpointhang-upfreqTypeofhang-up/typefreqDrawpointblocker1024m3Highhang-up 128m3Lowhang-up 16m3100%LHDbucket2m3DrawratesDrawrates/production3TypesGeotechicalAcceptableActualGeotechnical=Frag(BCF)+hang-upmodelsAcceptable=limitedgeotechnical(burstprotection)Actual=Acceptable-miningsystemreadinessDrawratereductionMiningsystemreadinessExtractionleveldamageConstructionbehindEquipmentnotavailableDrawpointsecondaryblastingcrewsnotavailableCrusher’sandinfrastructurenotoperationalDrawratereductionMiningsystemreadinessExtractionleveldamageConstructionbehindEquipmentnotavailableDrawpointsecondaryblastingcrewsnotavailableCrusher’sandinfrastructurenotoperationalDrawraterulesDonotexceed200mm/day(maturity)Softcavestartdrawrate75-100mm/dayHardcavestartdrawrate40-75mm/dayMiningsystemreadinessreduction25-40%BlockcavingdrawcontrolReasonPreventdilutionUniformdrawdownoforePreventpointloadingondriftsCommutationoforefragmentsPreventionof:-Airblasts-RockburstsTrueblockcaveOre/wasteinterfaceUniformdrawdown(massFlow)DrawpointsdrawnevenlyPANELCAVEDrawplaneCaveplaneMAINTAINSHAPEBlockcavedrawprinciplesWhatistheoveralldrawstrategy-Blockcave-PanelcaveAlldrawpointsdrawnevenlyAlldrawpointstodrawntoformcave/drawplaneTheopenareashouldbebigenoughtoachieveproductiontonnage(haveenoughdrawpoints)Theabovemusthave30-15%extradrawpointsSimpledrawstrategies-fewerdrawpoints,flatdrawplanesarebetterDifferentgeotechnicalareasfordrawrateDrawisaboutdisciplineRequireddrawdataAdrawreserveWhatisgoingtobeextractedbythecavedrawpointsDrawreserve:-Orereservecoveredbyextractionleveldrawbells-Typesofdrawreserve-Extractiondilutiontons/factors-Drawpointnumberandtonnage,tonnagetypes-shut-offlevel-driftrepairdataDrawcontrolDrawreserveadjustedtofootprintDrawpointshavetonsallocatedtothemDrawreservesVerticaldrawreserveWedgedrawreserveWASTEDWPTDefinedbybreakbackangleDailydrawdataBoggertonstakenfromdrawpointsDilutionDriftrepair/drawpointsoutDrawbeaconsdamagedDailyadjustmentofextractiondataComputerprogrammesReconciliation––underground5%SecondaryblastingBockcavesarelikeredwineolderbetterCoarserockstar