012.pdf

SME Annual Meeting Feb. 28-Mar. 03, 2010, Phoenix, AZ

1 Copyright 2010 by SME

Preprint 10-052

AN OVERVIEW OF THE PROPOSED DMLZ MINE

I. Duckworth, Freeport McMoRan Copper & Gold, Papua, Indonesia T. Casten, Freeport McMoRan Copper & Gold, Papua, Indonesia

M. Rakidjan, P.T. Freeport Indonesia, Papua, Indonesia

ABSTRACT

P.T. Freeport Indonesia operates a mining complex located in the highlands of Papua, Indonesia. This district consists of both underground and surface operations.

The East Ertsberg Skarn System (EESS) is one of the major orebodies in this district. Subsurface caving of the EESS has been carried out in a systematic series of mining lifts dating back almost 30 years. Present production is from the third lift (Deep Ore Zone), which is scheduled to peak at 80,000 mtpd during 2009, with this rate sustained through 2015. The orebody is proven below the existing caving level, with the next vertical block called the Deep Mill Level Zone (DMLZ).

This paper presents an overview of the DMLZ Mine based on recent feasibility level study. The mine is being designed for a peak production rate of 29.2 million mtpy, with 1,803 total ore draw points spread over a panel caving footprint of about 1.3km by 375m. The present reserves for this mine total 501 million tonnes. Located 1,400-1,800m below the original surface, the DMLZ will be one of the deepest caving operations in the world. Production is scheduled to commence in 2015.

Discussion is provided on most design aspects including; caving methodology and layouts, geotechnical predictions and risks, ore handling systems, ventilation design and associated infrastructure, high-lift pumping system, cost estimation and expenditure scheduling.

INTRODUCTION

The Deep Mill Level Zone (DMLZ) is within the Ertsberg Mining District in Papua, Indonesia. The Ertsberg District is operated by P.T. Freeport Indonesia (PTFI) under contract to the Republic of Indonesia. PTFI is currently producing copper and gold ore from the Grasberg Open Pit (GRS) and Deep Ore Zone (DOZ) Block Cave Mine. The GRS is scheduled for depletion in 2015/2016. PTFI plans call for replacement of GRS Open Pit production with ore from the following underground sources (Figure 1): DOZ Block Cave Mine: Presently in production and expanding to

80k mtpd (thousand metric tonnes per day) production during 2009 with closure in 2020.

Big Gossan (BGN) Open Stope: Under development and scheduled for initial production in 2010.

DMLZ Block Cave Mine: Early development commenced. Production scheduled to start 2015.

GBC Block Cave Mine: Under development and scheduled for production in 2016.

Kucing Liar (KL): Future cave adjacent to the GBC. The DMLZ block cave reserve totals 501 million tonnes at 0.89%

copper, 0.74 g/t gold, and 4.4 g/t silver. Total payable metal over the life-of-mine (LOM) is projected at 8.4 billion pounds of copper and 9.2 million ounces of gold. The mine is planned as a mechanized block cave operation with a peak production of 80k mtpd. Production from caving is scheduled to commence January 2015, reaching peak production during 2020 which is sustained through 2033. The mine

operates at or near 80k mtpd for 13 years and is projected to close in 2037

DOZDOZ

DMLZDMLZ

GrasbergBlock CaveGrasberg

Block CaveKucing

Liar

Grasbergopen pit

Grasbergopen pit

Plan ViewN

Portals(at Ridge Camp)

MLA

Common Infrastructure2,500 m elev

GrasbergBC Spur

Kucing Liar Spur

Big Gossan Spur DMLZ Spur

BigGossanBigGossan

Amole2,900 m elev

N

Mill

Portals

DOZDOZDMLZDMLZ

GrasbergGrasberg

Kucing Liar

Big Gossan

Figure 1. PTFIs Existing and planned underground mines.

Previous Studies The reserves that comprise the present DMLZ were previously

split into the Mill Level Zone (MLZ) and DMLZ, with the MLZ to be developed first and the DMLZ overlapping. Pre-feasibility level designs for both the MLZ and DMLZ were advanced during 2004/2005.

Since these original studies were issued, further exploration core drilling, updated resource calculations, and redefined metal pricing resulted in revisions to the orebody block model and the projected mineable footprint. As a result, the MLZ and DMLZ ore bodies presented during pre-feasibility study were combined into a single entity referred to in its entirety as DMLZ. The changes involved removal of all MLZ workings and a footprint expansion on the DMLZ 2590m Extraction Level. The revised DMLZ will provide earlier metal release when compared to twin lifts and a higher peak tonnage and metal production rate.

GEOLOGY AND HYDROLOGY

The DMLZ orebody is a part of the EESS. The EESS is a vertically continuous mineralized zone that is developed within diorite with proximal skarns along the northern margin. It is a single copper/gold diorite and sedimentary rock-hosted skarn orebody that has been subdivided into various mining volumes. The EESS was originally discovered through surface mineralization exposures, now no longer visible due to subsidence related to block caving operations. The mining volumes have been given different names for identification/mining level purposes. The upper part of the EESS, between the 4,000 and 3,626m elevations constitutes the Gunung Bijih Timor (GBT) deposit. The GBT was mined out by the mid-1990s. Below the GBT is the Intermediate Ore Zone (IOZ), located between the 3,456 and 3,626m elevations. This has also been mined-out. The DOZ is located below the IOZ and is situated between the 3,456 and 3,125m elevations. The DOZ is currently being mined from the 3,125m Level. The DMLZ reserve is located below the DOZ, between the 3,125 and 2,590m elevations hosted in both diorite (vein-style mineralization) and skarn (disseminated and vein style mineralization).



l pulley

-

- levation, head pulley 3,000m elevation, length

EESS mineralization continues downward from the current DMLZ reserves and is being actively explored for continuity along strike to the northwest.

A hydrologic finite element model was prepared for the DMLZ area (inclusive of DOZ). Results were computed LOM for the DMLZ. The lateral passive inflow, representing the portion of groundwater than can be effectively removed by dewatering programs, is predicted to peak at 785 lps by the end of the mine life. The modeling results indicate that there will be a critical inflow increase from present through approximately 2030, during which dewatering drilling must be aggressively executed. Up to 29 km of drilling per year is required, starting no later than 2015.

In terms of overall quantities, depending on how effectively water can be captured off the DOZ levels following closure of that mine, then the DMLZ water handling is estimated to peak at between 946 - 1,287 lps.

MINE DESIGN

General Development operations at DMLZ commenced in November

2008, with the start of the DMLZ rail spur leading from the AB Adits, and in January 2009 with the DMLZ conveyor and service decline access (Figure 2). The mine layout focuses on multiple main levels and key infrastructure installations, as indicated in the following list. All level values are elevations above sea level.

Main Mining Levels and Accesses - Undercut Level 2,605m, Extraction Level 2,590m, Intake

Level 2,565m, Exhaust Level 2,550m, Haulage Level 2,525m, DMLZ Terminal 2,525m.

- Internal Ramp between the Extraction Level and the bottom of the service decline.

- Other mine leKey I

vel access ramps. nfrastructure - Crushing Plants: Car dump on Haulage Level 2,525m,

transfer main conveyors 2,453m. - Main Pump Station 2,520m, discharge at 2,990m.

Incline Conveyor #1 and access decline: Tai-2,440m, head pulley 2,635m, length 1,355m. Incline Conveyor #2 and access decline: Tail pulley 2,625m elevation, head pulley 2,820m elevation, length 1,335m. Incline Conveyor #3 and access decline: Tail pulley 2,810m e1,440m.

AB Spur

Upper Ven

t

DMLZ Service Decline & Conveyor

VRs

FacilitiesCrushers

Mine Levels

Figu

the m

gth between the first and

orep

one s the

re 2. DMLZ Mine Development Schedule (Coded by Year). Production plans are centered on a block cave mining approach,

similar in many respects to current operations at PTFIs existing DOZ Mine. The major exception from the DOZ is the DMLZ is scheduled to use electrically-powered trains for primary ore haulage rather than diesel-powered haul trucks. This will ensure consistency of the production haulage fleet with the larger GBC Mine. Another departure from the DOZ operation is main 15% incline conveyors are planned to transport production ore up to the mill area. The DOZ, being located at

ill elevation, required relatively short, flat conveyors to transfer ore from the crushers to surface stockpiles.

The DMLZ ore body measures roughly 1,300m in length (oriented southeast to northwest) and is between 350 and 500m in width. There are 43 production panel drifts planned. Panel len

last drawpoints varies from 72m at the southeast end of the level, to 474m, with an average of 372m.

Orepasses are installed along the panel drifts at a maximum spacing of 170m. Twelve of the panels are short enough to require only a single orepass, and the eastern two panels share an orepass. The remaining 30 panels require two passes, for a total of 72

asses in the current design. Rock breakers are installed on 1m x 1m aperture grizzlies located at the top of each orepass.

The DMLZ ore body is to be mined using an advance undercut method as successfully applied in the DOZ. Drawbells are drilled and blasted from the drawpoint drifts into caved material previously blasted above on the Undercut Level (Figure 3). Drawbells are blasted in shot using programmable detonators. The undercut blast formmajor pillar apex; the drawbell blast forms the minor pillar apex.

Section Looking NW

Section Looking NE

Section Looking NW

Section Looking NE

Figure 3. Undercutting & Drawbelling Methodology.

Undercutting will lead drawbelling by a minimum of 15m horizontally. Undercutting will typically advance beyond this minimum point, but as a general rule should not lead drawbelling by more than three months. Exceeding this maximum creates an elevated risk of undercut re-compaction. Caving operations are commenced at the extreme southeastern end of the mineable footprint, sweeping across the ore zone from southeast to northwest along a blunted chevron cave

OD). The majority of production activ

rn end of the cline also provides a secondary escape route in

the e

sibility level assessment was

front. Caving is initiated at the apex of the chevron, and the wings of the chevron extend to the north and south.

The ore body has two distinct draw column height regimes, divided roughly in half along the long axis. Draw columns along the north side of the mine tend to be shorter in height, averaging approximately 245m height of draw (H

ity will occur in the southern half of the mine where HODs reach 526m, as indicated in Figure 4.

DMLZ primary personnel and material access is through the AB Adits, serviced from a surface rail yard using shared rail haulage infrastructure and rolling stock. Secondary access for rubber-tire equipment and service vehicles is through the conveyor access decline, which extends from the DOZ intake adits down to DMLZ. The service decline parallels the conveyor, from existing drifting down to the DMLZ crushing plant, located below the southeastemine. The service de

vent that the AB Adit systems are unavailable.

Geomechanical The DMLZ will be the deepest and highest stress block cave

mined in the Ertsberg District to date. Fea



carried out to establish key details with regards to the geomechanical aspects of the proposed operation.

DMLZ Ore Body

DMLZ Extraction North Fringe DriftDMLZ Extraction

South Fringe Drift

DMLZ Ore Body

DMLZ Extraction North Fringe DriftDMLZ Extraction

South Fringe Drift

Figure 4. Isometric View of the DMLZ Reserve.

Caving and Fragmentation: The DMLZ is caveable. Fragmentation is predicted to be similar to the diorite sections of the existing DOZ Mine. Experience gained in the DOZ will assist in refining the DMLZ fragmentation and drawpoint hang-up predictions. The DMLZ footprint has a hydraulic radius (HR) of 134m and based on Laubschers method requires a footprint with a HR of 30m to initiate caving and 56m to sustain caving.

Cave and Crack Limits: The DMLZ cave and crack limits were projected at five-year intervals for the project. On the south side, these limits generally do not extend past the furthest limit of the expected DOZ cracking (governed by prior caving above). In the other directions the surface crack limit will expand based on the cave angles (which vary by direction) and the increased depth of the DMLZ.

Interaction with the DOZ Mine: There is a 5 year overlap projected between first production in the DMLZ (2015) and final production in the DOZ (2020). Based on numerical modeling, adverse impacts to DOZ facilities are not expected within the first two years of DMLZ caving. Between years 2 through 5 the cave progresses upward and will be within 150 to 400m of certain critical DOZ facilities and related infrastructure. Prior experience within the EESS indicates that some damage to the openings will likely result as the cave progresses up, including rockfalls and increased convergence. The modeling indicates that during years 5 through 7 of DMLZ caving changes in the stress field are significant. Heavy support and rehabilitation of DOZ drifts will be required if certain openings have to be maintained.

Fixed Facilities and Mine Layout: Permanent facilities are located at or below the DMLZ Extraction Level at horizontal distances greater than

of th

150m to the south of the cave boundary. This minimum distance was recommended based on geomechanical assessment.

The proposed mine layout is considered feasible for the Undercut, Extraction, fixed facilities, and AB Terminal. There are concerns associated with certain drifts located in the northern skarns, which are considered at higher risk of collapse. Ground conditions are considered generally good to fair for all areas on the main mine levels, although further characterization drilling is required to improve confidence. Extraction panel drifts are oriented at N35E in the direction

e regional stress field and with respect to rock fabric. This orientation is consistent with the IOZ and DOZ mines.

Mining Schedule and Sequence: There are some concerns associated with the caving sequence and schedule adopted in the

siengi

1. e of at least 80m

3.

ic modeling and

fea bility study that are to be examined during the next phase of neering:

Based on convergence observations in the DOZ Mine, the active portion of the cave width should advance at a ratper year. During certain periods the DMLZ feasibility schedule does not meet this criterion. The advance rate averages approximately 65m/year for 2019 through 2025.

2. The undercut should be at least one drawbell in advance of drawbell completion and no more than three drawbells in advance. The DMLZ schedule meets this criterion.

The active cave width should not exceed some limit that is expected to be on the order of 400m. This cave width criterion is a function of the rock mass properties, cave geometry, depth and associated stresses based on parametrexperience at other caves. It is noted that DOZ has exceeded this criterion in 2009, however operational complications have been identified associated with the long cave front.

4. A linear to convex-shaped cave front should be maintained (cave shape criterion). DMLZ meets this criterion. Rock Stress: Stresses in the proposed Extraction and Haulage

levels start at approximately 50 to 60 MPa and are predicted to increase due to mining. High stresses of 80 MPa in diorite and up to 100 MPa in skarns and limestones are expected in the 80m zone in advance of the undercut, extending down to the Haulage Level. These stresses remain through mining on the northern fringe drifts of the Extraction Level. Stress results were analyzed with both elastic and Mohr-Coulomb models. Openings in diorite and skarn are expected to be serviceable but are predicted to have increased potential for bursting events when compared to the DOZ. Some of the stress effects on the northern fringe of the Extraction Level may be reduced by maintaining a linear cave boundary on the north.

Monitoring: Monitoring is required to assist in draw control and to understand how the stresses will be transferred in front of the cave and progress to the surface. Monitoring methods should be redundant and

be limited to; microseismic, time domain reflectometry

over a series of 1,829 mm conv

re most of the operational activity and much of the maintenance is staged. A tru

s, as well as the crusher station

LZ operation, due the impact of caving. However, a section of the horizontal ventilation drifting accessing the DOZ Mine can be utilized by connecting primary ventilation raises up from the DMLZ Mine.

include, but not (TDR), drift convergence, multiple-position borehole extensometers, load cells, fragmentation distribution, and hang-up frequency.

Oreflow DMLZ crushing infrastructure is similar to DOZ, utilizing twin

FLSmith FFE Minerals Inc. 54 x 77 gyratory crushers. These are to be fed by trains operating above on the DMLZ Haulage Level. Ore is transported to the surface stockpile

eyor belts totaling approximately 4 km in length. This conveyor system raises the ore 550m vertically from the crusher discharge up to an existing conveyor near the surface.

The crusher chamber (Figure 5Figure) is a multi-level facility designed to accommodate crusher installation, operation, and maintenance efficiently within a minimum excavated volume.

Access to the crushers is via the lower extension of the Internal Ramp. The top level is the crusher inlet, crane bay, and control room area. Situated approximately 22m below the Haulage Level, this level is whe

ck dump is provided in the upper access leading to both crushers, which will also be used for backhoe cleanout of the crusher bowl.

The eccentric access level is 16m below the crane bay. This level not only provides access to the eccentric for maintenance and replacement, but also houses the crusher electrical bay and thehydraulic system reservoirs and coolertransformers and high-voltage switchgear. The eccentric access initially serves as excavation access to the top of the crushed ore bin.

Ventilation and Refuge The DMLZ Mine will be developed below the existing DOZ. Much

of the DOZ ventilation infrastructure will be unavailable for ventilating the DM



Figure 5. Section of a Crusher Installation.

For the DMLZ the air will enter the mine through a combination of the DOZ Intakes (~70% of the intake volume), the Service Decline, and the AB Adit Spur. The primary intake system is completely open with no regulators or booster fans required. The majority of the intake air is routed down three 6m diameter raisebored shafts. This air is then transferred across the 2,565m Intake Level to the main mine levels. Intake air flows through a free-splitting network to intake ventilation raises along the north and south fringes, leading up to the Extraction and Undercut Levels, and down to the Haulage Level. Other minor splits are directed into various infrastructure and facilities areas. In all, approximately 7 km of ventilation drifting is required on the Intake Level. In addition, 1.6 km of 6m diameter raises, and approximately 400m of 3m diameter ventilation raises will be necessary.

All the air exhausts the mine via the 2,550m Exhaust Level, then up through five 6m diameter smooth raises. These raises connect to the DOZ Exhaust system, expanded to comprise five drifts and five parallel Howden-Australia 3.5m diameter mixed-flow axial fans. All mine exhaust is through these primary fans, inclusive of the ore flow allowance. The Exhaust Level serves multiple functions as primary exhaust ventilation, Haulage Level development access, and upper chute construction access. Early development of exhaust ventilation headings is critical to the development plan. One of the first development priorities is gaining access to the top and bottom of the first Exhaust Ventilation Raise to facilitate raise excavation.

The DMLZ Mine will have two separate intake air splits for emergency egress. The first is the AB Adit spur that will connect the lower mine to the portals. In the event of a fire anywhere but the actual AB Tunnels, this will remain clean of smoke and serve as an intake escapeway. The second escapeway is via the Service Decline. In the event of a fire in the AB Adits this route will remain clear of smoke and serve as an escapeway.

Within PTFIs existing underground operations egress is considered to be the first priority. However, since both escapeways are lengthy, and would involve transportation to fully evacuate the mine, permanent refuge stations are included at each main level allowing all personnel from those levels to wait in safety. PTFIs standard for refuge specifies a system incorporating oxygen generation, scrubbing

and refrigeration, with a rated capacity of 36 hours (MineARC or similar). Rail Dump Pumping

Water will report to the DMLZ mining area in increasing flow volumes as the mine transitions from preproduction to full production. The expanded subsidence area will increase surface collection, and broaden the volume in which subterranean sources may be intercepted. The majority of the water will be collected from sources throughout the DMLZ via a series of ditches on the various mining levels which will report to drainage on the Intake Ventilation Level. Any inflow entering the mine workings below the Intake Level elevation (namely the Exhaust and Haulage Levels) is directed to a Drainage Level via a system of ditches and drain holes. Flows are directed through the Drainage Level to a sump pump station installed at the lowest point in the DMLZ.

Coarse Ore Bin

Crusher

Approximately 505 lps of the DMLZ water capture is to be pumped up to provide water to the mill. The remainder will flow by gravity out of the AB Adit. The main pump station will consist of two operating banks of five pumps in series. In the event that a bank of pumps should go offline, the water bypasses the pump station and joins the overflow volume out the AB Adits. The main pump banks each comprise of five centrifugal slurry pumps driven by 447 kW motors. The first pump in each operating bank is equipped with a variable frequency drive to regulate discharge flow. This feature provides the ability to limit the number of main pump motor starts per hour.

Fine Ore Bin

Feeder & Belt

SCHEDULE, COSTS AND MANPOWER

Schedule and Costs The project schedule was prepared using Datamines Mine 2-4D

and Enhanced Production Scheduler (EPS) software. Vulcan was retained as PTFIs primary mine design tool.

The project schedule is driven primarily by excavations. Underground construction activities must wait for excavations to be completed. Construction time requirements are developed on a case-by-case basis and are entered into EPS as a hard duration.

A comprehensive coding structure was developed for the DMLZ. The full code is a 19-digit series comprised of four sub-codes, as follows:

Facility Code (two places) Asset Group (AG) Code (four places) Work Breakdown Structure (WBS) Code (four places) Estimating Code (nine places)

The Facility Code is derived from the layer names in Vulcan and allows costs to be cleanly grouped according to facility. An example would be a crusher with costs from excavation, fixed equipment, construction, EPCM, indirect and contingency grouped under one facility code. The next two codes, the AG and WBS, incorporate project control coding. Applied in combination, these codes ensure that costs are tracked correctly and reported into the appropriate cost areas. The last nine digits represent the estimating code. The estimating code is divided into six sublevels.

Level 1 Class Level Level 2 Type Level Level 3 Description Level Level 4 Single/Multi-task Level Level 5 Material Level (Ore or Waste) Level 6 Ground Support Level

The estimate code is used to link schedule quantities with estimate productivities, unit costs and resources (manpower and equipment). An example of an estimating code would be Contractor Capital (Level 1), Lateral Development (Level 2), 5.5m x 5.5m Drift (Level 3), Single Heading (Level 4), Waste Development (Level 5) and Medium Ground Support Classification (Level 6). Resources and consumables consistent with contractor crews driving a single-heading



5.5m x 5.5m drift with medium ground support would then be allocated against this quantity.

A significant effort was made to develop flexible and accurate cost models for the DMLZ. Zero-based procedures were used almost exclusively in preparing the capital and operating portions of the estimate. These components were then modified, as necessary, to reflect actual PTFI key performance indicators.

Manpower As PTFIs underground operations continue to branch out, the

provision of manpower becomes an increasing commitment. Attracting, training, and retaining a competent workforce for the various operations and projects is an ongoing challenge.

DMLZ manpower was estimated using ratios consistent with current DOZ direct and support staffing. Manpower is forecast to peak at 2,550 employees during the 2009 2021 preproduction and production ramp-up years, with a range of 1,950 to 2,400 for the full production period from 2022 through 2027 (final year of undercutting). As development activities taper off, manpower drops to about 1,550 persons by 2030. This number is maintained for the following few years, after which the workforce gradually drops to 750 persons by the end of the mine life in 2037. A graph showing LOM manpower by job category is presented in Figure 6. The numbers are inclusive of all rotation crews, indirect manpower, vacation and sick leave, absenteeism and training.

-

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

2,400

2,600

2009

2010

2011

2012

2013

2014

2015

2016

2017

2018

2019

2020

2021

2022

2023

2024

2025

2026

2027

2028

2029

2030

2031

2032

2033

2034

2035

2036

2037

Year

-end

Man

pow

er

PTFI Development Construction PreproductionProduction Mechanics and Electricians UG Management and AdministrationUG Technical Services Gen Services & CIP Contractor (Excavation)

Figure 6. DMLZ Manpower by Department.

RISK

The DMLZ represents the continuation of caving of the EESS. The caving design and peak tonnage are consistent with the present DOZ, and as such there is considerable confidence associated with caving of the DMLZ. PTFI is one of the world leaders in block cave mine production, having successfully constructed and extracted three previous caves, all within the EESS. The operational risks are therefore considered to be manageable; however, insufficient data in some areas raises concerns that elevate risk profiles.

During feasibility study a total of 119 risks were identified associated with the development and operation of the proposed DMLZ Mine. Out of the highest 22 risks, ten of these related to geomechanical concerns such as high stress, knowledge of structures, burst potential, wet drawpoints and early dilution.

A number of the risks, both geomechanical and operational, were connected with the undercutting sequence and the concern that the cave front stresses and abutment loading will result in damage, or rock conditions that impact upon development and caving schedules and costs. A reassessment of the undercutting sequence during basic engineering has been identified as a critical area of focus.

Operationally, one of the key risks is associated with the ability to handle tramp steel which can result in nuisance shutdown of the ore handling system, or in extreme cases damage. In the DOZ this is an ongoing issue and one worthy of further study.

Five of the higher level risks are connected with staffing, manpower and associated housing and support facilities. It is

recognized that the timely sourcing and training of sufficient personnel (at all levels) represents one of the highest risks to successful on-time completion of the DMLZ project. The combination of the remote location coupled with multiple large projects peaking at similar times, will stretch resources.

CONCLUSIONS

The DMLZ is both technically and financially feasible and PTFI has made the decision to move forward with the development of this new mine.

As with most large projects a number of areas have been identified where additional data or further studies are necessary to improve knowledge and understand/mitigate risk. These technical studies and design work are presently commencing in order to advance knowledge beyond the level of the feasibility study. Early development of critical openings started late 2008, and development will ramp up significantly during the next 4 years, peaking at about 15 km during 2013.

At this time the first drawbell tonne is schedule for January 2015, with peak production of 80k mtpd achieved during 2020.

ACKNOWLEDGEMENTS

The authors wish to thank the management teams of PTFI and Freeport McMoRan Copper and Gold for permission to prepare and publish this paper.

REFERENCES

P.T. Freeport Indonesia, Deep MLZ Mine Feasibility Study, Draft, 460p.

ABSTRACTINTRODUCTIONPrevious Studies

GEOLOGY AND HYDROLOGYMINE DESIGNGeneralGeomechanicalOreflowVentilation and RefugePumping

SCHEDULE, COSTS AND MANPOWERSchedule and CostsManpower

RISKCONCLUSIONSACKNOWLEDGEMENTSREFERENCES

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012.pdf