AGA Australia ANGLOGOLD ASHANTI AUSTRALIA Utilisation of underground RC drilling and operational impacts at Sunrise Dam An Innovative Approach to Underground Grade Control Fraser Clark Manager: Geology
OVERVIEW Sunrise Dam has transitioned from a large scale open pit Open Pit Commence 1997 Average 400Kozpa 7.3Moz mined 6Mtpa Average grade 3.9 g/t 16Mt stockpiled Underground Commence 2003 Average 140Kozpa 1.96Moz mined 1.4Mtpa Average grade 3.35 g/t Current rate 3Mtpa 2..to a highly productive underground mine @ 3Mtpa
THE SUNRISE DAM JOURNEY There has been a significant transition from a large-scale open pit mine Gold Produced (oz) 650 Underground Ore Mined (Mtpa) 3.0 600 550 500 450 400 350 300 250 200 2.5 2.0 1.5 1.0 150 100 0.5 50 0 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018F 0.0 Gold Produced - Open Pit Gold Produced - Stockpiles Gold Produced - Underground Underground Mined Tonnes to a stand alone underground operation. 3
ORE DEFINITION CHALLENGES Gold mineralisation is extremely complex.. 4.it requires good quality, dense sampling for successful ore definition prior to mining.
ORE DEFINITION UNDERGROUND Underground mining presents numerous technical challenges to mining geologists.. Lack of exposure Lack of access Lack of dense drilling Poor sampling techniques Complex sampling patterns Reliance on mapping High uncertainty 5 Misclassification..with broad spaced diamond drilling supplemented by qualitative information
APPLICATION OF WET REVERSE CIRCULATION DRILLING UG RC provides a route to increase sampling density and sample support (volume). 121mm diameter holes (43kg primary sample) 14 times larger than half core Water injection to suppress dust 1.5m rods 1.5m Sampling intervals Rotating cone splitter 10m ring spacing Ability to drill 360 rings Average holes length 30m 16 holes per ring - 22.5 increments Penetration rates 7m/h (140m/day) per rig...quickly and cheaply 6
RIG SET UP 7
RC GRADE CONTROL PATTERN RC drilling conducted from one level drilling 360 degree rings. 8 covering two mining levels from one location
RIG PERFORMANCE Sunrise Dam has a fleet of 6 RC rigs drilling in excess of 20Km per month.. 9.delivering 300Kt of ore into the mine plan per month.
QUALITY CONTROL Detailed QA and QC has demonstrated that wet RC sampling is robust QA Program (Bulk sampling) Sub sample comparison to the Lot granulometric bias testing grade bias testing Mass balance Loss of fines QC Program Duplicate/Triplicate sampling for imprecision Sub sample weight monitoring 10..with sample recovery and imprecision equal to or better than surface RC drilling
ORE DEFINITION RC Drilling has unlocked the complexity of the mineral resource Faster than diamond drilling Cheaper than diamond drilling Larger sample volumes More samples No downstream core processing = BETTER ORE DEFINITION providing a fast and effective tool for stope definition and mine planning. 11
ORE DEFINITION RC grade control provides good quality ore definition. 12.allowing precise mine design and minimising ore loss and dilution
RC GRADE CONTROL MODEL RECONCILIATION The reconciliation between the GC model defined by RC is robust 1.80 Short Term Factor - 24 Months 1.60 1.55 Plant/GC Factor 1.40 1.20 1.00 0.80 0.60 1.21 1.15 0.97 0.97 0.97 1.00 1.02 1.01 1.05 1.01 0.95 0.94 0.94 0.97 1.12 1.07 1.26 1.16 1.08 1.11 1.14 1.13 0.99 1.01 1.04 1.09 1.00 1.00 0.96 0.97 0.96 0.95 0.98 0.96 1.00 1.05 1.07 1.06 1.02 1.03 1.01 1.02 1.02 0.99 0.95 0.96 1.00 0.95 0.94 0.40 0.20 0.00 Month Tonnes Grade.demonstrating predictability over short and long time periods 13
GRADE CONTROL STOCKS Building up the Grade Control stocks to >18 months ahead of mining. 2015 2018 Improved mine design and planning 14. to underpin the budget cycle and ensure reliable delivery.
THE FUTURE Drilling 150m RC holes to improve reserve confidence ahead on mine planning Advanced Grade Control 150m holes 2 years ahead of production Improved reserve confidence Improved mine design, scheduling and budget delivery 15 leading to improved planning and budgeting decisions.