butcher a, et al (2010) - northparkes mine

8/12/2019 Butcher a, Et Al (2010) - Northparkes Mine

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Title: NORTHPARKES MINES

Authors: A Butcher1, R Cunningham2, K Edwards3, A Lye4, J Simmons5, CStegman6and A Wyllie7.

1. Manager, Ore Processing and Logistics, Northparkes Mines, PO Box995, Parkes NSW 2870, Australia.

2. Manager, Special Projects and Tunnel Boring Systems (TBS),Northparkes Mines, PO Box 995, Parkes NSW 2870, Australia.

3. Manager, Health, Environment, Safety, Communities and FarmsNorthparkes Mines, PO Box 995, Parkes NSW 2870, Australia.

4. General Manager, Projects, Northparkes Mines, PO Box 995, ParkesNSW 2870, Australia.

5. Personal Assistant to the Managing Director, Northparkes Mines, POBox 995, Parkes NSW 2870, Australia. Email:[email protected]

6. Managing Director, Northparkes Mines, PO Box 995, Parkes NSW

2870, Australia. Email: [email protected]. Superintendent, Mine Design, Northparkes Mines, PO Box 995,Parkes NSW 2870, Australia.

Publication: AMMOP

Contact person: Craig StegmanManaging DirectorNorthparkes MinesPO Box 995, Parkes NSW 2870, AustraliaPhone: +61 2 6861 3117Mobile: +61 (0) 457 430 897

Fax: +61 2 6861 3102Email: [email protected]


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INTRODUCTION

Overview

Northparkes Mines (Northparkes), an unincorporated joint venture between Rio Tinto (80 percent), Sumitomo Metal Mining Oceania (13.3 per cent) and Sumitomo Corporation (6.7 percent), operates block cave and open cut mines and an ore processing plant located 27 kmnorth of Parkes in central New South Wales (Figure 1). The mine site is located at anelevation of 230 m above sea level on the plains to the west of the Great Dividing Range inthe headwaters of the Bogan River, which is part of the Murray Darling Basin. The landsurrounding the operations is mainly used for farming (a mixture of dry land cereal croppingand sheep/cattle grazing). Annual rainfall is in the range of 400 - 1000 mm (average 600 mm).Northparkes Mines owns 6000 hectares of land around the mine, of which the mining leasescover 1630 hectares. The remaining land is actively farmed.

Production commenced in 1993 and the operation has produced approximately 750 000tonnes of copper and approximately one million ounces of gold to the end of 2010(approximately 20 per cent from open pit and 80 per cent from underground). Ore is currentlysourced from the E48 Lift 1 block cave mine (the third block cave) and open cut stockpiles.Approximately 5.8 Mt/a of ore is processed annually on site, producing 140 000 - 150 000 t ofcopper and gold concentrates that are shipped to custom smelters in Japan, China and Indiafor smelting and refining.

A production summary is given in Table 1. The current life of mine is 2024, based onReserves of 75.5 Mt of ore grading 0.82 per cent copper and 0.32 g/t gold (as of 31December 2010). Northparkes has a large resource base of 287.8 Mt grading 0.57 per centcopper and 0.26 g/t gold.

Northparkes currently has approximately 700 full-time equivalent employees, comprisingapproximately 300 staff and 400 contractors. Most employees live in Parkes and theneighbouring town of Forbes.

History

North Limited acquired the Northparkes project through its merger with Peko Wallsend in the1980s. North approved the Northparkes project, comprising underground block cave andopen cut mines and concentrator, in 1992 following an extensive and lengthy studies phase.The low-grade nature of the Northparkes deposits and their relative depth precluded manyconventional underground mining methods. North subsequently formed the Northparkes joint

venture with Sumitomo Metal Mining Oceania and Sumitomo Corporation in 1993 in order toobtain a development partner with downstream smelting and refining capability. Rio Tintoacquired North Limited in 2000 and assumed management of the Northparkes joint venture.The joint venture partners approved construction of the E26 Lift 2 block cave mine in 2001.Mining of the Lift 1 block cave mine was completed in October 2003 prior to completion ofthe Lift 2 mine. Concentrator production was maintained by undertaking a further cutback inthe E27 open cut mine. Production from the Lift 2 mine began in August 2004.

The joint venture partners approved the E48 Lift 1 block cave mine in November 2006.Large-scale production from the E26 Lift 2 block cave mine ceased in August 2007, muchearlier than planned and again prior to completion of the new block cave mine. As a result,further mining took place in the E22 pit and an extension of the Lift 2 block cave mine, theE26 Lift 2 North block cave, was constructed. These two ore sources allowed concentrator


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production to be maintained in full through the transition period, which was extended bynearly a year due to a nine-month suspension of construction of the E48 Lift 1 mine in 2009due to the global financial crisis. Production ramp-up from the E48 Lift 1 block cave minecommenced in 2010 with the new block cave mine becoming the main ore source in late2010.

Operating strategy, constraints and innovation

Northparkes current operating strategy primarily reflects the unique configuration of the E26,E22, E27 and E48 deposits. The deposits are all relatively small compared to porphyrycopper deposits worldwide, although they are vertically continuous and in close proximity toeach other. At the time of mine start-up, the deposits were regarded as low-grade. Inaddition, the deposits are hosted in very competent rock-types. Whilst the near-surfaceportions of the deposits were ideally suited to open cut mining, the deeper sections weremore problematic. They could not be economically extracted by conventional undergroundmining methods like long-hole open stoping. The small footprints of the deposits andcompetent rock-types appeared to preclude caving mining methods.

After much research and study, Northparkes finally adopted a highly modified block cavemining method to extract the deeper resources. Block caving has allowed Northparkes toachieve very low mining costs and high productivities by industry standards, mainly throughthe application of very efficient automated material handling and comminution systems thatminimise ore re-handle, including high speed electric load haul dump units, jaw-gyratorycrushers, high-speed conveyors and shaft hoisting systems. However, all of Northparkesblock caves are characterised by high height to width ratios and cave footprints that are veryclose to the minimum hydraulic radius required to initiate continuous caving. This hasrequired considerable innovation to improve caveability, including hydro-fracturing anddrilling and blasting of the rock mass to reduce rock strength.

The block cave layout has evolved considerably since the first block cave mine, with eachsubsequent mine representing an improvement on the previous version. Other factors thathave influenced the design and operating strategy of Northparkes operations include:

The construction lead-time for block cave mines is significant and typically of the order ofthree to four years, requiring significant upfront planning.

Block cave production rates are intimately tied to the rate of caving; production rates willbe reduced if cave propagation slows. Likewise, there is a much higher chance ofincomplete reserve recovery in block cave mines compared to more conventional miningmethods. As a result, it has been important for Northparkes to establish alternate oresources to cope with production shortfalls from the block cave mines.

The closeness of Northparkes deposits has also allowed considerable sharing of

infrastructure, including mine access, material handling and ventilation systems, and alsofacilitated the sequential extraction of progressively deeper and lower-grade ore bodies.

Proximity to major established infrastructure, including the Newell Highway, the junctionof Australias east-west and north-south rail corridors that provide rail access to a numberof ports, regular air-services to Sydney and the main Australian East Coast electricitygrid.

Proximity to a number of key regional centres, including Parkes, Orange and Dubbo,which provides ready access to a significant pool of employees and contractors, as wellas engineering and maintenance groups. This has also allowed Northparkes to operateas a residential operation.

Lack of appreciable water resources in close vicinity to the mine has required

Northparkes to source its water from the Lachlan River and aquifers 60 km to the south ofthe mine. Many townships and other industries also depend on these resources,


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especially during droughts, highlighting the importance of minimising water usage andimproving water recycling.

Location within traditional farming areas has resulted in a strong focus on creating aeffective buffer between neighbouring farming operations and the mine, includingminimising noise, traffic interactions and continuing to use available land for cropping.

General infrastruc ture

Northparkes requires approximately 3600 ML water per annum to process a nominal 5.8 Mtof ore. Most of this water is sourced from a bore field adjacent to the Lachlan Riverapproximately 60 km south of the mine. A small amount of water is also abstracted from theLachlan River. Water is piped to Parkes via infrastructure shared with the Parkes ShireCouncil and then to the mine through a dedicated water pipeline. Electricity needs ofapproximately 215 GWh, at an average load of around 24.5 MW, are met entirely from themain East Coast Australian electricity grid. The bulk of the electricity is consumed by theunderground crushers and hoist and the grinding circuit in the concentrator.

Future plans

In August 2010 Northparkes Mines announced the approval for a $90 million pre-feasibilitystudy (subsequently increased to $115 million) assessing the potential to extend mine lifebeyond 2024. This project envisages a large-scale mining and processing operation basedon a series of larger lower-grade resources located within existing mining leases. The keypart of the pre-feasibility study will be a major evaluation drilling program, involving in excessof 155 km of drilling, which will assess identified copper and gold mineralisation within theexisting mining leases beneath current mining operations on the E26, E48 and E22 deposits,and at the GRP314 area of mineralisation (Figure 2). Central to the pre-feasibility study willbe community consultation and the assessment of both existing and new technology that willdeliver environmental outcomes including improving water, energy efficiency and

biodiversity. It is anticipated that the pre-feasibility study will take approximately two years tocomplete at which time the Joint Venture partners will determine whether to progress to afeasibility study.

GEOLOGICAL DESCRIPTION

Exploration activities in the Northparkes area were initially undertaken by the corporateexploration groups of Geopeko and North Limited until 1998. From 1998 onwards,Northparkes has managed all exploration in the district, focussing exclusively on theGoonumbla Volcanic Complex. A combination of magnetic, gravity and electrical geophysicalsurveys, bedrock geochemistry, geological interpretation and deep diamond drilling has beenused to help discover new porphyry systems including the GRP314 deposit. Recent

exploration activities have provided extensive deep drill coverage in the mine corridor. Thishas led to the discovery of additional mineralisation at depth beneath existing miningoperations at E22, E26 and E48 deposits. The ore reserves and resources according to theJORC code are listed in Table 2.

The Northparkes deposits occur within the Ordovician Goonumbla Volcanics of theGoonumbla Volcanic Complex (Simpson et al, 2000). The Goonumbla Volcanics form part ofthe Junee-Narromine Volcanic Belt of the Lachlan Orogen (Glen et al, 1998). TheGoonumbla Volcanics consist of a folded sequence of trachyandesitic to trachytic volcanicsand volcaniclastic sediments that are interpreted to have been deposited in a submarineenvironment. The Northparkes deposits are typical porphyry copper systems in that themineralisation and alteration are zoned around quartz monzonite porphyries. The porphyriesform narrow (typically less than 50 m in diameter) but vertically extensive (greater than 900


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m) pipes. Mineralisation extends from the porphyries into their host lithology. The E26 andE48 deposits range from 60 m to 400 m in diameter (>0.4 per cent copper) and extendvertically for more than 1100 m. Figure 3 shows a north-south geological cross-section of themain resources.

Sulfide mineralisation occurs in quartz stockwork veins, as disseminations and fracturecoatings. Highest grades are generally associated with the most intense stockwork veining.Sulfide species in the systems are zoned from bornite-dominant cores, centred on the quartzmonzonite porphyries, outwards through a chalcopyrite-dominant zone to distal pyrite. As thecopper grade increases (approximately >1.2 per cent copper), the content of covellite,digenite and chalcocite associated with the bornite mineralisation also increases. Goldnormally occurs as fine inclusions within the bornite. Bornite is the predominant ore mineralin all deposits. Copper to gold ratios differ between the different deposits and withinindividual deposits. The E22 and E27 deposits have lower copper to gold ratios compared tothe E26 and E48 deposits. In all deposits, the copper to gold ratio decreases towards thecentre of the deposit. All the Northparkes deposits are cross cut by late faults/veins filled withquartz-carbonate and minor gypsum, anhydrite, pyrite, tennantite chalcopyrite, sphalerite and

galena. The associated sericite alteration extends up to 10 m from the fault. Tennantite,which contributes arsenic to the final copper concentrate, is present in higher concentrationsin the E48 deposit.

Oxide mineralisation blankets were well developed over the E22 and E27 deposits. Theupper blanket was gold-rich and copper-poor. The lower blanket was enriched in copper bysupergene processes. The dominant copper oxide minerals at E22 and E27 were coppercarbonates (malachite and azurite) and phosphates (pseudomalachite and libethenite) withlesser chalcocite, native copper, cuprite and chrysocolla. A gold-poor, less well developed,supergene copper blanket was also developed over the E26 deposit. At E26 the oxidecopper minerals included atacamite, clinoatacamite and sampleite, in addition to thosecopper minerals observed in E22 and E27.

The Goonumbla Volcanics at Northparkes have undergone little deformation, with gentle tomoderate bedding dips as a result of regional folding. The dominant structure observed todate in the Northparkes area is the Altona Fault, an east dipping thrust fault, which truncatesthe top of E48 and GRP314, and is known to extend from east of E26 to E27.

MINING OPERATIONS UNDERGROUND

Overview

Northparkes was the first mine in Australia to use a variation of the cost-effective block cavemining technique in its underground operations. Northparkes is currently mining its third

block cave mine (Table 3 and Figure 4).

Pre-production mining development work consists of establishing two working levels, theundercut level and extraction level, at the base of each ore block, as well as the developmentto support the associated material handling system. Northparkes has developed its ownunique extraction level layout that locates the material handling system, including crusher, tothe side of the extraction level, thereby alleviating the need to construct a third leveldedicated to haulage. Similarly, it has established the extraction level as the primaryventilation level, thereby eliminating development to support mine ventilation. The undercutlevel, which is used to initiate caving, is 14 - 20 m vertically above the extraction level; theheight being dependent on the undercutting method. Undercutting, which involves sequentialfirings of overlapping fans of blast holes to create the initial void for caving, is the ratecontrolling step for production ramp-up, controlling both the rate of undercutting ore and then


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the start of production from draw points. Northparkes has consistently set record levels forundercutting. During the recent E48 campaign, an average of twelve draw bells and 7000 m2of undercut were blasted per month, allowing the undercutting to completed in 12 months.Rapid undercutting can in part be attributed to firing draw-bells in a single firing usingelectronic detonators. Following draw bell blasting, the associated draw points are broughtinto production with production rates ramped up to full production over a period of three to sixmonths.

A number of undercutting methods have been used. The E26 Lift 1 cave utilised a doubleundercut (two undercut levels) in an attempt to increase productivity from the cave duringproduction ramp-up. Subsequent caves relied upon a single undercut level. Both the E26 Lift1 and Lift 2/2N caves employed an advanced undercut method; essentially, draw points anddraw bells were installed after the undercut level had been blasted. In contrast, the E48 Lift 1cave utilised a post-undercut method where draw points and draw bells were constructedprior to undercut blasting. The advanced undercut method is best suited to higher stressconditions where it is important to minimise openings to preserve the strength and integrity ofthe extraction level rock mass.

Geotechnical description

Northparkes has established comprehensive geotechnical models for all of its block cavemines. The models are based on geotechnical logging of extensive diamond drill core datasets, augmented by mapping of underground openings established during the early studyphases. For example, a total of 57 NQ and HQ drill holes and wedges for 35 000 m of drillingwere completed at the E48 Project and an exploration drive was developed across the E48extraction level during the feasibility study to validate the drill core data. The geotechnicalcore logging comprises both interval logging and detailed oriented fracture logging. This dataallows the rock mass to be characterised in terms of rock quality designator (RQD) and thevarious rock mass rating systems (MRMR, Q system and RMR system), fracture density and

fracture orientations. In addition, geophysical logging of selected drill holes is undertaken tocompliment the geotechnical logging. Other data collected includes point load strength tests,over-core stress measurements and UCS rock strength measurements.

The Northparkes rock mass, including the E48 and E26 deposits, is a highly jointed rockmass with fracture frequencies of between three and 20 per metre and with fracture densityincreasing with copper grade. The volcaniclastic and volcanic units tend to be more highlyfractured than the monzonites and porphyries. Rock strengths range from 90 - 150 MPa withlocally weaker zones associated with late stage shears. The maximum principle stressdirection is sub-horizontal and striking northwest-south east with a magnitude of 30 - 40 MPaat the E48 extraction level. The minimum principle stress direction is sub-vertical.

Standard ground support comprises 2.4 m resin-encapsulated rock bolts installed on a onemetre pattern, complimented with 50 - 75 mm of fibre-reinforced shotcrete. All intersectionsare cable bolted using twin-strand 6 m long cables. In areas of higher stress, for example,draw points, additional cabling, meshing and strapping will be installed.

Mine planning practices and procedures

Block cave reserves are estimated with PCBC software based on mixing and dilutionparameters derived from reconciliations of earlier block cave mines (eg E26 Lift 1 and Lift 2).Recent upgrades to the software, including template mixing, have allowed the effects oflateral flow and toppling to be better estimated. However, it is still necessary to closelymonitor actual draw point grades and draw point geology to validate the reserve models,including the effects of preferential migration of finer particles and of dilution. Checks are also


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made by shadowing the PCBC models with REBOP simulations (particle flow models).Reserves are typically estimated by depleting the original reserves for production andaccounting for cave shape.

Production plans are based on life of mine PCBC models based on the predicted draw plan.Northparkes mostly draws its block caves to an even height of draw. However, once breakthrough has occurred, selective draw can be established to achieve either higher gradeproduction and/or to stimulate cave propagation. However, a minimum draw is generallymaintained across the extraction level to minimise the potential for localised loading on thelevel.

Mining process and equipment

Figure 5 shows the layout of the E26 Lift 2 Block Cave mine and Table 4 gives a list of theunderground mining equipment. Figure 6 shows the E48 Lift 1 mine material handlingsystem.

Mine access for all personnel and equipment is provided by surface portal and decline. Thedecline has a standard 6 m by 6 m arched profile. The hoisting shaft represents the secondmeans of egress and the ore skips can be fitted with a man-riding cage in the event thatpersonnel cannot egress the mine via the decline.

The mine ventilation system consists of two surface mounted 750 kW exhaust fans mountedabove a system of vertical and lateral return air raises. The primary air intakes are the maindecline and the hoisting shaft. Draw is balanced to control air velocity in the hoisting shaftdue to the risk of displacing hoisting components at excessive air velocities. The ventilationsystem typically operates at airflows of 390 - 400 m3per second, which are shared acrossthe various work areas,

Water inflows to the mine are relatively modest of the order of 3 - 5 L/s. Dewateringsystems are installed at the base of each extraction level and are designed to cope with largeinflows from the cave volume and subsidence zone.

The mining process involves recovery of broken rock from the draw points by 14 t capacityelectric Load Haul Dump Units (LHDs), which tram the ore to a primary crushing station,consisting of plate feeder and jaw gyratory crusher, located on the margin of the extractionlevel. Typically, four to five LHDs operate on a continuous basis to achieve daily productiontargets of 18 kt per day. Oversize rock is broken on the extraction level using specialistsecondary breaking drills. Draw point hang-ups are addressed with a combination of watercannons and high hang-up drill rigs. Extraction level layout has evolved considerably toaddress a range of design elements, including:

concurrent LHD operations to maximise extraction level productivity; LHD access to multiple drives to improve operational flexibility; roadway designs to allow high-speed (fourth gear) LHD tramming; crusher configuration to reduce the volume of secondary breaking; ventilation flows and dust suppression systems to ensure dust from loading operations is

minimised; drainage to control water flows and direct away from the extraction drives; communications systems to allow single point control of extraction level operations; maintenance facilities located on the margins of the extraction level to maximise LHD

availability; and


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extraction level infrastructure to support operations, maintenance and service crews,including crib rooms and fresh air bases.

The material handling system employed at Northparkes has been designed to minimise orerehandling and is fully automated. Ore is fed to a coarse ore bin that feeds the primarycrusher. Two jaw crushers were employed in the E26 Lift 1 mine but subsequent minesutilise a single jaw-gyratory crusher. Crushed ore is fed onto high-speed inclined conveyorsvia an ore pass that also provides storage capacity. Ore is conveyed to the undergroundloading station, which consists of three ore passes feeding the hoisting system. The hoistingsystem consists of a ground mounted friction winder with integrated drum and rotor, servicingtwo 16 t payload skips in counterbalance, running on rope guides in the 6 m diameterconcrete-lined shaft. Considerable work has been undertaken to improve the capability of thehoisting system, which represents the mining operations key bottleneck. This work hasmainly focused on improving the availability of the hoisting system.

Hoisted ore is transferred via a short conveyor to a secondary crushing station located nearthe head frame. The secondary crusher, which was installed as part of the E48 Project,

reduces the ore to a P80 of 55 mm, improving the overall capacity of the concentrator circuit.Ore from the secondary crusher to then conveyed to the concentrator by a curved highspeed conveyor that skirts the E48 subsidence zone.

The underground mining operation has approximately 80 full-time employees, consisting ofmine management and operations, technical services and maintenance teams. Theoperations team has four crews working 12-hour shifts. Each crew consists of a team leader,five LHD operators, three secondary breakers, two conveyor belt runners and aSCADA/Database operator. A service crew is also employed to maintain basic infrastructureand services in the mine, including road grading and stores transport. The technical servicesteam comprises approximately 12 staff including mining and geotechnical engineers andtechnicians. Approximately 25 mechanical and electrical maintenance personnel manage the

physical assets in the mine.

Cave management, ore control and reconciliation procedures

Northparkes has developed a comprehensive cave management system based on itsexperiences with operating the E26 block caves. These management systems are designedto manage the specific catastrophic safety risks particular to block caves; namely airblast,surface subsidence and inrush and large-scale rock falls. The system is also designed tosupport maximising reserve recovery and optimising mine production. The system is basedon a large number of monitoring systems, including real-time microseismic event monitoring,open hole surveys using probes and video cameras, time domain reflectometers installed ingrouted boreholes, convergence monitoring using extensometers and manual measurements

of mine openings on the extraction level and in key underground infrastructure, draw pointfragmentation and geology mapping, draw point grade sampling, subsidence zone volumeestimates and water inflow measurements.

These data are reviewed on a monthly basis and monitored against triggers that form part offormal triggered action response plans (TARPs) that have been developed in conjunctionwith the mining inspectorate.

Draw point grade control samples are collected at a rate of two to three samples per drawpoint per month to allow monthly reconciliations of sampled grade against concentratorgrades and predicted reserve grades. Towards the end of the life of the block cave mine, thegrade control samples are used to determine draw point shut-off strategies.


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Innovation and improvement

Notable technology applications included the application of microseismic and other remotemonitoring cave management systems, hydro-fracturing for cave propagation, use of electricloaders and jaw-gyratory crushers.

Northparkes block caves are amongst the most heavily monitored in the industry, whichreflects the complexity associated with block cave mines characterised by small footprints,high heights of draw and relatively strong rock mass. The development of very sensitivemicroseismic monitoring systems in the pre-production stages of mine development hasallowed Northparkes to very accurately map and track the distribution of micro-seismicevents in the mine environment, leading to an improved understanding of cave propagationprocesses, as well as improving safety management and reserve recovery.

Hydro-fracturing was first applied at Northparkes in 1998 to assist with the Lift 1 cavepropagation in areas of competent rock mass and relatively low stress environment. Hydrofracturing proved successful in stimulating cave propagation in the E26 Lift 1 cave and has

been applied to the E26 Lift 2 North and E48 Cave volumes prior to caving. Whilst difficult toquantify, hydro fracturing is believed to have substantially assisted cave propagation in bothcases.

The use of six electric powered loaders as the primary production fleet was the first of its sizein the industry. This application provided many benefits over conventional diesel poweredloaders, most notably reduced maintenance costs, longer equipment life and a significantreduction in carbon emissions and corresponding ventilation requirements. This loader fleethas demonstrated superior performance over an extended period of time with operationallifetimes of in excess of 13 years and 30 000 operating hours.

A single jaw-gyratory crusher was installed as part of the E26 Lift 2 mine. The primary

advantage of this style of crusher over conventional crushers is its ability to accept amaximum rock size of three cubic metres whilst achieving a consistent P80 of 120 mm,thereby dramatically reducing the secondary breaking burden on the Extraction Level. As aresult, a grizzly screen is not required on the crusher feed bin, although a rock breaker isfitted to the crusher to address periodic blockages in the crusher and on the plate feeder.

MINING OPERATIONS OPEN PIT

Overview

Open cut mining has been used to access the near surface portions of the copper-golddeposits at Northparkes, initially to allow accelerated ore processing prior to commissioning

of underground operations, but also to supplement underground production during thetransition from one cave to another. As a result, open cut mining has typically beenundertaken on a campaign basis, often relying upon contractor mining. The most recentcampaign in E22 pit, which was completed in September 2010, was managed by utilising anumber of major contractors. All heavy earthmoving equipment (excluding drill rigs) wassupplied by a contractor as a maintained dry hire fleet with rates based on engine hourutilisation. Drilling was undertaken by a specialist drilling contractor on fixed and metre rates.Operators were sourced from a local labour hire company on casual rates and explosiveswhere supplied by a contractor with loading and tie by Northparkes operations team. A totalof 25 Mt of rock was extracted from the E22 pit during this campaign, including 12 Mt of ore.Nine million tonnes of ore has been stockpiled for future processing.

Geotechnical description


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The E22, E26 and E27 open cuts were all roughly circular in shape, with diameters of up to600 m and ultimate depths of up to 220 m. The E22 and E27 pits were both mined in threestages; the initial pit followed by two cut-backs. Typical ore waste ratios were of the order of1:2.

Each of the open cut mines at Northparkes encountered very weak surface clays andweathered rock to depth of 30 - 50 m before transitioning to highly fractured unweatheredvolcanic and intrusive porphyry rock-types, the latter often located in the pit centre. Theserock types were over-printed by widely spaced, large-scale, steeply dipping sericite-alteredfault zones. Fracture density and hydrothermal alteration intensity typically increased towardsthe porphyries. In addition, most fractures dipped inwards to the pit centre. As a result, pitwall stability was a major challenge during mining operations.

Batter angles in the surface clays and weathered rock were between 30 - 45 degrees. Whilstthis produced stable walls in most circumstances, there were localised failures due to acombination of surface and ground water and larger scale discontinuities. As a result,

considerable focus was placed on managing drainage around the pit walls and on drillingdepressurisation holes in the pit walls.

Batter angles in the sulfide rock in the early mining campaigns were in the range of 55degrees to 60 degrees. However, by reducing blast damage through the use of trim shots,pre-split drilling and reduced blast bench heights and introducing a range of ground support(shotcrete and cable bolting), batters were successfully steepened to 80 to 90 degrees.Berms were initially 5 m wide but were increased to 8 m in later mining campaigns inconjunction with the steeper batters to improve catch capacity. Bench heights were typically20 - 21 m.

A combination of geotechnical mapping, constant wall monitoring and ground penetrating

radar was also employed to assist with pit wall management.

Mine planning

Pit designs were based on Whittle optimisation utilising long-term metal price assumptionsand minimum mining width criteria based on mid-sized excavator-truck fleet.

Mining process and equipment

Mining of the open pits typically involved medium-sized (180 to 220 t) hydraulic excavator inbackhoe configuration and a fleet of 85 - 100 t trucks, together with an array of conventionalancillary equipment, including rotary blast hole drill rigs, graders, dozers and water carts. All

pits utilised a single 20 - 23 m wide 1:7 ramp for access. The width was based on two-waytraffic for the haul trucks. The ramp width was reduced in single lane near the pit bottom.

Initial excavation of weathered clay and rock did not require blasting and could be free dug.However, at depths of between 10 m and 30 m, harder rock was encountered which requiredblasting before excavation. The standard blast hole pattern was 3.5 m x 4 m with a blastbench height of 5 - 7 m. Hole diameter ranged from 102 mm in early campaigns to 15 mm inlater campaigns. ANFO was used in the upper benches but emulsion was used in lowerbenches where ground water was likely to be encountered. Latter mining campaigns usedUnitronic electric detonators. Hole diameter ranged from 102 mm and 89 mm blasting drillholes for Unitronic electric detonators.


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Waste rock removed from the open cuts has been formed into sound bunds around theperimeter of the pits to minimise transmission of noise and dust to neighbouring properties.The waste rock has also been used in the construction of the tailings storage facilities. Orewas either directly tipped on a run of mine stockpile near a surface crusher for immediateprocessing or placed in a series of grade-controlled stockpiles.

Ore control and reconciliation procedures

Early campaigns used reverse circulation drilling for grade control. However, reversecirculation caused significant delays to the mining process and was replaced with blastholecone sampling with one sample per blast hole. Whilst sample quality was reduced, overallsample density was higher, resulting in an overall improvement to grade control quality.Quality control through the onsite lab was checked by using field duplicates every 25samples and inserting certified standards every 40 samples. Grade control blocks wereestimated by block modelling methods using kriging. A minimum practical mining block wasset at 15 x 20 m. A range of high, low and marginal grade bands were used for stockpilingwith the waste material cut-off based on break-even processing costs based on long term

forecast prices.

PROCESSING OPERATIONS

Mineralogy and characterisation

The E48 ore body is the dominant supply of ore to the concentrator, with 100 per cent ofsupply provided since late 2010. Stockpiles of open cut E22 ore are held, and provide abuffer for short supply from the underground mine. The main copper bearing minerals fromall ore bodies processed are bornite and chalcopyrite.

The E22 ore is lower grade than the E48 ore body and is characterised by lower bornite:

chalcopyrite ratios. As copper grade increases the content of covellite and chalcociteassociated with the bornite mineralisation increases. Rare visible gold occurs as inclusionsup to 1mm in diameter within bornite or more rarely as free gold in quartz veins. Due to theintimate relationship with bornite, visible gold tends to occur within the highest-grade zonesof the central portion of the deposit. Chalcopyrite is the dominant sulfide species outboard ofthe bornite rich core. Chalcopyrite occurs as disseminations within veins and wall rock, andfrequently occurs along fine fractures. Pyrite is generally restricted to the lower gradeperipheries of the mineralisation, outboard of the chalcopyrite dominated zone. Concentratecopper grades of 33 per cent are typically achieved compared to 35 per cent from the E48ore.The ore mineralogy of the E48 deposit consists of bornite as the dominant copper-sulfidespecies and occurs in association with significantly smaller, but variable amounts of

chalcopyrite and chalcocite. Gold and silver are present largely as small particles (often 38 m size fractions.

The arsenic in the E48 ore is hosted almost entirely by tennantite that is present as smallgrains (usually


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required. This may be the subject of further studies as the mine develops and Asconcentration increases in the product.

Process description

Ore processing consists of four stages: crushing, grinding, flotation and thickening/filtering.The flowsheet is shown in Figure 7. The process plant equipment and process plantconsumables are listed in Tables 5 and 6, respectively. Table 7 presents a typicalmetallurgical balance. The ore processing team also manages tailings disposal andconcentrate logistics to port.

The concentrator was constructed in two modules, namely Module 1 and Module 2. Eachmodule consists of its own grinding circuit, flotation circuit, concentrate thickener and filter.The tailings are combined in a single tailings thickener before being deposited in one of threetailings storage facilities.

The Module 1 grinding circuit was the first to be constructed along with a gold Carbon-in-

Leach circuit. The upper gold oxide sections of the E27 and E22 ore bodies were processedthrough Module 1 during the initial 18 months of operation at Northparkes (~1993) to producegold bars. During this period, Module 2 was constructed and featured a grinding circuit andcopper oxide flotation circuit. Once gold production ceased in Module 1, the CIL plant wasdecommissioned and Module 1 was converted into a sulfide flotation circuit. Copper oxideore was processing from 1995, followed by copper sulfide ore.

The operating philosophy is simple: maximise plant throughput, then recovery, followed bygrade. Key performance metrics are assigned to all process variables and are monitoreddaily in order to better understand the sources of variation in the process. Corrective actionsare taken to eliminate assignable causes to control stability and thereby improve the plantscapability for greater production rates and product quality.

The metallurgical accounting system is based on a process mass balance. A softwarepackage developed by Matrikon (ProcessMORe) is used to record downtime and productionresults. A JK SimMet model and empirical models are used to evaluate production plans andforecast process outputs.

The ore processing department has approximately 50 full-time employees, consisting ofmanagement and operations, metallurgy and laboratory teams. The operations team has fourcrews working 12-hour shifts to achieve 24/7 production. Each crew consists of a teamleader, two grinding operators, two flotation and thickener/filter operators and a tailings andwater storage operator.

A service crew is also employed to maintain basic infrastructure and services in the plant,including water supply, grinding media and reagents delivery management. The oreprocessing department also manages tailings disposal and concentrate logistics by road andrail to Port Kembla, NSW.

The metallurgy and laboratory team comprises approximately 12 staff including metallurgistsand laboratory personnel. The laboratory is responsible for all metallurgical testwork andassaying as well as providing services to the mining and exploration departments.Approximately 30 mechanical and electrical maintenance personnel manage the physicalassets in the concentrator. Concentrator maintenance is provided by the asset managementdepartment, which manages maintenance across site, including the underground mine.

Crushing and ore handling


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Northparkes has two adjacent coarse ore stockpiles (Rill Tower stockpiles) that are able toreceive crushed ore via conveyor from both the surface (open cut mines) and undergroundcrushers. A secondary (cone) crusher was installed in early 2011 and is located between theprimary underground crusher and the ore stockpiles. The total capacity of each stockpile is150 000 t. Crushed ore is reclaimed from the base of each stockpile by four vibratingfeeders.

Grinding

The grinding circuit is made up of two separate modules, each incorporating semi-autogenous grinding (SAG), oversize pebble crushing, two stages of ball milling and flotation.Module 1 has a maximum design capacity of 245 t/h and operates at 95 per cent utilisationfor an annual throughput rate of 2.2 Mt/a. Module 2 has a maximum design capacity of 425t/h and operates at 95 per cent utilisation for an annual throughput rate of 3.6 Mt/a. Theserates have been exceeded during periods of processing high clay material and also followingthe recent installation of a secondary crusher, to produce a finer feed to the mills.

The ore from the stockpile feeders is discharged on to a conveyor feeding each SAG mill.Feed size (F80) to the SAG mill was historically 100 - 150 mm, however following the recentsecondary crusher installation, the F80 is now approximately 55 mm. Steel balls (125 mmdiameter) are added to the SAG mills as the grinding charge. Acoustic monitoring systemsare installed on both SAG mills and mill charge is controlled to both sound and power setpoints. The SAG mill is in closed circuit with a vibrating screen and an oversize pebble conecrusher. The vibrating screen has an aperture size of 8 mm. The oversize is fed to the pebblecrusher to produce a


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cleaner cells and conventional cleaner scavenger flotation cells to upgrade the quality of theproduct. The final tailing from each module is pumped to a common tails thickener fordewatering.

Overall metal recoveries from processing E48 Lift 1 cave ore average 91 - 92 per centcopper and 75 - 80 per cent gold. Similar recoveries were achieved for the other mainNorthparkes ore types. Concentrate grades are in the range 34 - 40 per cent copper and 15 -20 g/t gold. The principal penalty elements are arsenic, fluorine and Al2O3/MgO.

Copper recovery and grade are controlled in the flotation circuit using a MSA online analysissystem. Scavenger feed grade, final tail grade and concentrate grade are the main controlvariables used to ensure the plant is operating optimally. Cascade control loops are alsoutilised to adjust reagent doses depending on the feed tonnage.

Concentrate thickening and filtration

Final concentrate from the flotation circuits is pumped to thickeners where it is thickened to

an average underflow density of 60 per cent solids to maximise water recovery. Thickenedconcentrate is then pumped to concentrate storage tanks prior to treatment through thefiltration circuit, using ceramic filters. The filtered concentrate is discharged onto slow movingconveyor belts, each equipped with a weightometer to determine final production ofconcentrate. Typical moisture contents of concentrate vary between 7 and 9 wt%.

Tailings storage and water management

All tailings are pumped from the processing plant using two of three sets of slurry pumps toeither of the two active tailings storage facilities (TSF 2 and the E27 in-pit storage). Twopipelines are used to transport the tailings 2 km from the processing plant to their finalstorage point in central decant storage facilities. Both TSF 1 and TSF 2 have surface areas

of approximately 100 hectares, and water recovery off TSF 2 is about 30 per cent. Wallconstruction is comprised of clay and rock. Northparkes has recently undertaken tailingsdisposal in the abandoned E27 pit, and water recovery from this pit is about 50 per cent.Water is recovered from the tailings storage facilities for use back in the processing plant.Water recovery is optimised by maximising the tailings thickener density and using the sitesdeep water storage facilities, E27 and Caloola.

Concentrate logistics

Copper concentrate is loaded into 26 t capacity lidded steel containers in a coveredconcentrate storage facility in the processing plant. The loaded containers are transportedtwo at a time by road freight from the mine site to the Goonumbla rail siding approximately 15

km from the mine. The containers are stored at the siding before being railed to Port Kembla.Each train load contains approximately 1500 t of concentrate. The containers are emptied atthe port and returned to site. The concentrate is stored in a covered shed until a 10 000tonne cargo is ready for shipping to custom smelters in Japan, China and India.

Innovation and improvement

A number of improvement programmes and innovations are underway. Opportunities thathave been identified include: reviewing the feed size of the SAG mills, introducing visualmanagement systems, and the development of standard response plans. The site has alsoinitiated deployment of the Lean/Six Sigma project management methodology. In 2011, anumber of projects will be completed that address key business drivers for productivity: millthroughput, recovery and asset reliability. Current projects underway include:


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secondary crusher performance for mill feed optimisation, SAG mill discharge grate aperture performance, water chemistry optimisation, and SAG mill total charge optimisation.

ENVIRONMENT AND COMMUNITY

All activities are conducted in accordance with the Northparkes safety, health, environmentand community policy and are aligned with Rio Tintos environment standards. Northparkeshas also commenced life of mine planning and stakeholder consultation in accordance withthe Rio Tinto closure standard, the relevant Rio Tinto community standards and associateddocumentation. The mine closure planning process is closely aligned with the principlesoutlined in ANZMEC/MCA Strategic framework for Mine ClosureAugust 2004. Northparkesmanages environmental risks as part of an integrated HSE management system. Thissystem is audited and is certified under the ISO14001 certified Environmental ManagementSystem standard. The EMS outlines the minimum standard to ensure NPM manages its

environmental aspects in a manner that is planned, controlled, monitored, recorded andaudited, using a system that drives continual improvement.

The key environmental targets and performance for 2009 and 2010 are summarised in Table8. The principal environmental issues involve noise and dust management, managing landdisturbance and ensuing rehabilitation, managing water quality and controlling site water.Rehabilitation at Northparkes incorporates the entire landholding and not just the areacovered by the mining leases. Progressive rehabilitation conducted onsite is integrated withthe surrounding land owned by Northparkes and is managed with a view to enhancing theregional landscape and native habitat values.

The Northparkes mine closure plan (MCP) is consistent with the requirements of Condition

17 of Schedule 3 and relevant statement of commitments, Appendix 3 of the ProjectApproval (06-0026). The MCP is a living plan that evolves with the ongoing operations atNorthparkes, which are anticipated to continue until at least 2024. The mine closure strategyis based upon the Rio Tinto closure standard and associated guidelines. It comprises a mineclosure vision, closure objectives, goals, targets, performance indicators and end-use of landselection criteria.

A research project was commenced in 2008 with the Centre for Mined Land Rehabilitation(CMLR) to develop a tailings storage facility capping design for the closure of TSF1 andTSF2 to ensure maximum stability and minimal risk to the external environment. Stage 4 ofthe project, planned for 2011, includes field trials to test and validate the modelling resultsobtained in stage 3 and to gain confidence in the appropriateness of the final cover design.

Northparkes recognises its responsibility to the community in which it operates and iscommitted to minimising the impacts from its operations. Northparkes is also committed toengaging with the local community to support and build capacity for economic growth andlong term sustainable. Responsibility for community performance rests with the Manager forthe Health, Safety, Environment, Community and Farms. The key stakeholders thatNorthparkes engages with on a regular basis include: the local community, traditionalowners, neighbours and local landholders, local and state Government and Southern CrossLandholders. These relationships are managed through the following forums:

The Community Consultative Committee (CCC). Established in 2006, the CCC

comprises 15 members representing communities throughout the region including


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Parkes, Forbes, Peak Hill and Trundle. It has representatives from council, education,sports, business and other key organisations.

Aboriginal Heritage Working Group (AHWG). The AHWG was established in 2008 andmeets on a quarterly basis. It consists of representatives from the local WiradjuriCommunity and Northparkes Mines and manages the implementation of the Aboriginal

Heritage Management Plan. This plan provides the framework for the identification,assessment, monitoring and management of Aboriginal cultural heritage on site.

Neighbours meetings. Neighbours meetings are generally held twice a year with theMines closest neighbours to provide a feedback and a consultation mechanism.

The Parkes Borefield Committee. This committee consists of representatives fromNorthparkes, Parkes Shire Council and the Southern Cross Landholders and meets on aquarterly basis to better understand user impacts on the local aquifer.

New South Wales Minerals Council. Northparkes is an active member of the New SouthWales Minerals Council (NSWMC) and is often involved in active debate influencingpolicies and legislation relevant to the mining industry.

Northparkes believes that to maintain a strong social license to operate it must have apositive influence on the long term development of the communities impacted by itsoperations. The Northparkes community investment program was established to addressthis. The program has three tiers: partnerships, sponsorships and donations. It focuses onfour key areas: health, education and youth, environment and economic development.

OCCUPATIONAL HEALTH AND SAFETY

Northparkes follows the Rio Tinto risk management framework, and in particular the three-level risk assessment methodology. This methodology is designed to ensure the mostappropriate tool and/or approach is applied to identify, evaluate and treat hazards and risks

and allows for an escalation of risks to more formal complex quantitative assessments.

Level one of the methodology involves hazard identification which is every Northparkesemployees responsibility and is achieved through the Northparkes formal hazardidentification process which is either a basic TRACK (think, recognise, asses, control andkeep safety first) assessment or a team based job safety analysis (JSA). Hazards can alsobe identified, recorded and assigned to a physical work area to ensure future risk evaluationsare completed and controls /actions implemented. Northparkes uses the Rio Tinto BusinessSolution to record and report this information (including the construction and management ofits site risk register, incident and action management processes and audit records).

A site wide risk register is generated from the level two (qualitative) risk assessment process

and each leader is responsible for managing the risks in their particular work area. Risks thatare evaluated as critical or high (with a major or catastrophic consequence) are escalated toa level three quantitative assessment. SQRA (semi quantitative risk assessment) is usedto evaluate those safety risks requiring a level 3 assessment. SQRA risk scenarios arereviewed annually and a risk reduction (by calculating the reduced potential loss of life (PLL)score is measured annually).

All health and safety risks are managed through the Northparkes integrated managementsystem. This system conforms to Rio Tintos health, safety, environment and quality (HSEQ)management system standard and includes elements for management of change andcontractor management. This system is audited on annually by an external accreditedcertification provider and incorporates the Rio Tinto health, safety and environmentperformance standards.


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Major health hazards and their risks include noise, dust exposure, manual handling andfitness for work. These are managed through risk assessment and the Rio Tinto healthstandards.

Major safety hazards include vehicle interaction on and off site, moving parts on fixed ormobile plant, electrical safety, working at heights, confined spaces, underground fire andunderground rock fall. These hazards are managed through the SQRA and the Rio Tintosafety standards.

MANAGEMENT AND ORGANISATION

Organisational structure

Northparkes Mines operates with a non-unionised workforce, currently employingapproximately 300 full time employees and approximately 400 contractors working at themine site. Approximately 79 per cent of employees reside in Parkes, eight per cent in Forbes;

two per cent in Peak Hill and the remainder reside in other smaller towns within the ParkesShire (Rio Tinto, 2009). The organisational structure is illustrated in Figure 8. Table 9summarises the site personnel by department.

Human resources challenges

Historically, Northparkes has intentionally recruited its operational workforce from the localarea, which has resulted in a loyal and stable workforce with historically low (


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construction contractors who support major projects such as plant upgrades and constructionof tailings storage facilities, to specialist maintenance services groups to technicalconsultants across its business. One of the largest groups of contractors involved at site arethe maintenance contractors that support planned maintenance of mine and concentratorfixed plant during major maintenance shutdowns.

Risk management

A range of external and internal risks and opportunities have been identified through formalrisk assessment that potentially impact Northparkes operations over the plan period. Thefollowing risks and opportunities have been identified and ranked according to theirprobability of occurrence and the potential intensity:

Major safety incident. Northparkes remains exposed to major process safety typeincidents.

Volatile metal prices. Whilst copper and gold prices are tracking historical highs, therecent Global Financial crisis highlighted the speed at which prices could fall. In the case

of copper, prices fell by 60 per cent in less than six months. Metal prices are expected toremain volatile in the short-medium term due to ongoing uncertainty about the pace ofChinese and Indian growth and the pace of recovery of the United States and Europeaneconomic recoveries.

Delayed E48 mine ramp-up. Northparkes 2011 production plan assumes 5.7 Mt ofproduction from the E48 block cave mine. There is significant risk around achieving theplanned production ramp-up of the E48 mine if there is incomplete or slow cavepropagation or geotechnical instability on the extraction level (resulting from theundercutting method.

Incomplete E26 Lift 2N/E48 Lift 1 reserve recovery. Northparkes 15 year mine lifedepends upon fully recovering the E48 Lift 1 and remaining E26 Lift 2/2N reserves.Approximately 35 per cent of the original E26 Lift 2 reserves were not recovered due to

incomplete cave propagation, resulting in significant business disruption and lost value. Skills shortage. The ongoing resource boom in Australia is driving a skills shortage,

ranging from engineers, geologists and metallurgists to trades and operators. Theskills shortage is also driving a rapid escalation in salaries, putting significantpressure on operating and capital costs.

A qualitative risk analysis is conducted prior to commencement of all projects. A key outputof the analysis is a project risk register which is updated throughout the project. The purposeis to identify all significant risks to a project and to develop strategies to manage the risks.The intent of the risk analysis is not to replace the safety and health risk management toolsand systems already in place, such as semi quantitative risk analysis (SQRA). Furtherdetailed safety and health risk assessments are carried out prior to starting projectdevelopment and construction activities.

An ESH Management Plan is developed at each project gateway, in line with Northparkesrisk management framework (Table 10). The plan will be founded on a comprehensive riskmanagement framework linking over-arching high-level semi-quantitative project riskassessments to mid-level quantitative risk assessments (eg WRACs) to task-based jobsafety analyses and standard operating procedures (Table 10). Risk assessments build uponthe extensive onsite experience during the E26 Lift 2, E26 Lift 2 North and E48 Projects andindustry experience.


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REFERENCES

Glen, R A, Walshe, J L, Barron, L M and Watkins, J J, 1998. Ordovician convergent marginvolcanism and tectonism in the Lachlan sector of east Gondwana: Geology, v. 26, pp 751-754.

Lye, A, Crook, G and Kolff van Oosterwijk, L, 2006. The Discovery History of the Northparkes

Deposits, Mines & Wines Conference, 25-26 May 2006, Cessnock NSW [online]. Available

from: [Accessed: 25 July 2011].

Rio Tinto, 2009. Northparkes Mines 2009 Sustainable Development Report [online].Available from: [Accessed:25 July 2011].

Rio Tinto, 2010, Northparkes Mines 2010 Sustainable Development Report [online].

Available from [Accessed: 25 July 2011].

Rio Tintos interest in Northparkes Mines, Information Memorandum, April 2008.

Simpson, C, Cas, R A F and Arundell, M C, 2000. The Goonumbla Caldera, Parkes, NSW:fact or fiction? in Understanding planet earth: Searching for a sustainable future (Eds: C GSkilbeck and T C T Hubble), Abstracts for the 15th Australian Geological Convention,University of Technology, Sydney, Australia, 2000.


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LIST OF TABLES

Table 1 - Production summary.

Table 2- Northparkes ore reserves and resources, as at 31/12/2010.

Table 3 - Northparkes block cave mines.

Table 4- Underground mining mobile equipment list.

Table 5- Process plant equipment list.

Table 6- Process plant consumables.

Table 7 - Typical metallurgical balance.

Table 8- Northparkes key environmental targets and performance.

Table 9- Current site personnel numbers.

Table 10 - Risk management framework.

LIST OF FIGURES

Figure 1 - Aerial view of Northparkes Mines operations (December 2010).

Figure 2 - North-south cross-section showing step change project mineralisation targets.

Figure 3 - North-south geological cross-section showing main resources.

Figure 4 - North-south cross-section showing Northparkes block cave mines.

Figure 5 - Schematic layout of the E26 Lift 2 block cave mine.

Figure 6- E48 Lift 1 mine material handling system.

Figure 7 - Flowsheet of Northparkes concentrator.

Figure 8 - Site management structure (May 2011).

Table 1. Production summary.

2010 actual 2011 plan

Ore mined underground (Mt) 3.61 5.62Ore sourced open pit (Mt) 1.61 0.14Ore milled (Mt) 5.25 5.70Head grade Cu (%) 0.82 0.88Head grade Au (g/t) 0.51 0.48Copper produced (t) 38 986 45 857Gold produced (oz) 65 279 67 611


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Table 2. Northparkes ore reserves and resources, as at 31/12/2010.

Reserves - 31 December 2010

Tonnage (Mt) Copper (%) Gold (g/t)75.51 0.82 0.32

Inferred Resources as of 31 December 2010


Total Resources as of 31 December 2010


Table 3. Northparkes block cave mines.

Block Blockfootprint

Blockheight

Reserve Drawpoints

Years ofoperation

E26 Lift 1 200 x 200 m 450 m 27.2 Mt at 1.44 %Cuand 0.41 g/t Au

122 1997-2003


102 2004-2007

E26 Lift 2N* 180 x 90 m >350 m 9.3 Mt at 0.82 %Cuand 0.23 g/t Au

69 2008-2010


214 2010 Onwards


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Table 4. Underground mining mobile equipment list.

Equipment type Number

Sandvik LH514E Load Haul Dump Unit fitted with Automine software, 14tonne bucket and 430 m long trailing cable

5

Diesel operated Toro 1400D loader 1Single boom Tamrock drill rig with remote capabilities fitted with explosivecharge up facilities

1

Single boom jumbo with remote capabilities fitted with drill string carouselfor drilling longer holes in large hang-ups

1

Tamrock Commando 120 rock drill utilised for breaking loose oversizematerial in the draw points

1

Tamrock Commando 300 rock drill utilised for drilling loose oversize in thedraw point as well as blocked draw points and hang-ups

1

Grader 1ISUZU Table Top Truck 1Franna Crane 14 tonne 1

CAT IT28G (IT) 1Case1840 (Bobcat) 1

Table 5. Process plant equipment list

Item Number, size, manufacturer and installed power

ComminutionSAG mills Mod 1: 1 x Allis Mineral Systems, 7.3 m x 3.6 m, 2800 kW

Mod 2: 1 x Allis Mineral Systems, 8.5 m x 4.3 m, 4900 kWPebble crushers Mod 1: 1 x Sandvik CH440, 220 kW

Mod 2: 1 x Sandvik CH440, 220 kWSecondary ball mills Mod 1: 1 x Allis Mineral Systems, 4.8 m x 7.6 m, 2800 kWMod 2: 1 x Allis Mineral Systems, 5.5 m x 9.4 m, 4900 kW

Tertiary ball mills Mod 1: 1 x Allis Mineral Systems, 3.6 m x 5.5 m, 1300 kWMod 2: 1 x Falk, 4.05 m x 6.005 m, 1600 kW

FlotationFlash flotation Mod 1: 1 x Outotec SK500, 1 x Outotec TC5

Mod 2: 1 x Outotec SK1200, 1 x Outotec TC5Pre-flotation Mod 1: 1 x retrofitted cell

Mod 2: 1 x Outotec TC200, 225 kWRoughers/scavengers Mod 1: 2 x 4 cell banks, Dorr Oliver DO600 cells, 30 kW

Mod 2: 2 x 4 cell banks, Dorr Oliver DO1000 cells, 37 kW

Cleaners Mod 1: 1 x Jameson 2250, 6 downcomersMod 1: 1 x Jameson 1000, 1 downcomerMod 2: 1 x Jameson 2750, 8 downcomersMod 2: 1 x Jameson 1500, 3 downcomers

Cleaner scavengers Mod 1: 1 x 4 cell banks, Dorr Oliver DO300 cells, 15 kWMod 2: 1 x 4 cell banks, Dorr Oliver DO300 cells, 15 kW

DewateringConcentrate thickeners Mod 1: 1 x Superflo 10m

Mod 2: 1 x Superflo 10m

Concentrate ceramicfilters

Mod 1: 1 x Outokumpu CC-30Mod 2: 1 x Outokumpu CC-30

Tailings dewatering 1 x Superflo 28.5 m


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Table 6. Process plant consumables.

Item g/t

ComminutionSAG 125 mm steel balls 710Ball Mills 65 mm steel balls 840Ball Mills 30 mm HiCr balls 110

FlotationPAX 4DSP601 Promotor 10-12NaHS 25-40DSF611 Frother 10-12DSF007 Frother (scavs only) 2

DewateringAN934SH Tailings flocculant 30-33

Table 7. Typical metallurgical balance

Stream Mass (%) Grade Cu(%)

GradeAu(g/t )

DistributionCu (%)

DistributionAu (%)

Feed 100 0.82 0.51 100 100Rougherconcentrate(excl. flashcon)

4 10-15 4-7 75 50

Final

concentrate

2.5 32-35 15-20 91 77

Tailings 97.5 0.07-0.09 0.10-0.15 9 23

Table 8. Northparkes key environmental targets and performance.

2009Plan

2009Actual

2010Plan

2010Actual

Six per cent reduction in total green house

gas emissions by 2013 (t CO2-e)

217 928 209 017 209 446 208 572

Freshwater use, per tonne of product by 2013(ML/t product)

34 34.64 32 41.08

4.3 per cent increase (to 1307 ML) in use ofrecycled water (as a proportion of total waterused) by 2013.

26.9 33.5 27.9 32.47

Five year cumulative rehabilitation(disturbance /rehab ratio) from 2009 to 2013

0 0.62 0.33 0.67

Electricity consumption per tonne of ore milledby 2011 (GJ/t ore milled)

0.1479 0.14 0.1458 0.149


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Table 9. Current site personnel numbers.

DepartmentActual

manningVacantroles Total

Executive 3 2 5Ops - mining 74 15 89

Ops - ore processing and logistics 43 3 46

Ops - asset management 83 12 95

Commercial 22 6 28

Business effectiveness 6 4 10

HSEC&F 22 5 27

People and capability development 14 0 14

Projects 5 0 5

Projects - infrastructure 5 0 5

Projects - mining studies 4 4

Projects - geoscience 16 1 17Projects - tunnel boring 1 0 1

Total 298 48 346

Table 10. Risk Management Framework.

Risk assessment hierarchy Risk assessments

Semi-quantitative riskassessments (SQRAs) andqualitative risk assessments(QRAs)

Northparkes Minesite semi-quantitative risk assessment(SQRA)E48 project semi-quantitative risk assessment (SQRA)step change project risk analysis

Activity-specific QRAs Undertaken for each contract package and each majordevelopment stage over the project life

Mobile fit for purpose QRAs Undertaken for all equipment procured and utilised onsite

over the life of the projectProject risk register Utilising the Rio Tinto RioRisk spreadsheet and ultimately

the RioRisk software package once releasedStandard operatingprocedures (SOPs)

SOPs developed for project development and constructionactivities based on detailed job safety analyses (JSAs)


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910

980

L

945

910

980

L

945

Figure 1.

igure 2. No

L

L

E26

Lift 1

Lift

2/2N

Lift

L

L

E26

Lift 1

Lift

2/2N

Lift

Aerial vie

rth-south c

GRP314

3Lift

Step Cha

Infrastruct

GRP314

3Lift

Step Cha

Infrastruct

of Northp

oss-sectio

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ge

ure

oisting

haft

ConveyorD

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ure

25

rkes Mine

showing f

clines

E48

Lift 1

Not

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Lift 2

clines

E48

Lift 1

Not

mined

Lift 2

s operatio

uture proje

ConcentratorConcentrator

s (Decem

t mineralis

E22

Lift

E22

Lift

er 2010).

ation targe

Monzonite

Stock

E27

1

1 kilometre

Monzonite

Stock

E27

1

1 kilometre

s.


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Figure 3. North-south geological cross-section showing main resources.

Figure 4. North-south cross-section showing Northparkes block cave mines.

Quartz Monzonite Porphyry

Monzonite Stocks

Altona Fault

Monzodiorite

Latite dominant volcanics

0.5% Cu

Latitic Sediments

Trachytic Sediments

U/G Drives

0 1 km

E26 E48 E22 E27

Hoisting Shaft

Main

Decline

9800 Level

ConveyorDeclines

Access Decline

9450 Level

S N

E26

L1

E48

L2 L2N

L1L1


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Figure 5. Schematic layout of the E26 Lift 2 block cave mine.

Access Decline

Extraction Level

Draw Bell

Undercut Level

Crusher

Chamber

Extraction

Drive

North South

Conveyor Drive

Ore Body


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Item Description Capacity1 Load haul dump units, Tamrock 1400E 12 t bucket2 ROM bin 800 t live3 Plate feeder 1000 t/h4 Gyratory crusher, BK160-190 1000 t/h5 Crusher ore bin 400 t live6 Vibratory feeder 1050 t/h7 Conveyor, 124CV013 (1000 mm belt width, 35 trough, 3.0 m/s) 1050 t/h8 Belt weigher 1050 t/h9 Tramp magnet(self-cleaning type) -10 Tramp magnet (manual cleaning type) -

11 Metal detector -12 Conveyor, 124CV010 (1000 mm belt width, 35 trough, 3.1 m/s) 1050 t/h13 Fixed rock breaker -14 Hydroset trolley and ore pass cover plate -15 Ventilation fans -16 60 t SWL and 12 t overhead crane -

Figure 6. E48 Lift 1 mine material handling system.

121CV008

ORE BODY CAVE

124CV

010

EXISTING SHUTTLECONVEYOR AND LIFT 1ORE BINS

DRAW POINTS

TRAMMING LEVEL

E26 LIFT 2 C RUSHING ANDCONVEYING SYSTEM

E26L

IFT2

E26L

IFT2

124CV011 124CV010

1

2 16

13

14

3

4

5

6

9

TRAMP BIN8

7

12

15

1110

124CV012

124CV013

W/S AREA

DRIVE THR OUGH ACCESS

RELOCATED FOR CLARITY


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Figure 7. Flowsheet of Northparkes concentrator.


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Figure 8. Site management structure (May, 2011)

Managing

Director

Operations

UndergroundMining

Ore Processng

Asset Management

Projects

Geoscience

TBS

Infrastructure

Environment &Community

Mine Design

Health, Safety,Environment,

Communitites andFarms

Health, Safety &EmergencyResponse

Health, Safety &

EmergencyResponse

Farms

Underground Safety

People & CapabilityDevelopment

Human Resources

Surface Training

UndergroundTraining

Finance

Finance andAccounting

Business

Effectiveness

butcher a, et al (2010) - northparkes mine

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