UNDERGROUND MINE GEOLOGY

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UNDERGROUND MINE GEOLOGY

AUGUST, 2018

E. Christiani Aloysius

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2

AGENDA

• Introduction

• Role of Geology in Mining Industry

• Role of Geology in Underground Mine PT. Freeport Indonesia

• Discussion

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Role of Geology in Mining Industry

POWERED BY COPPERROLE OF GEOLOGY IN MINING INDUSTRY

• Mining operations are complex and Expensive. They aren't your run-of-the-mill type projects. Consist of various interconnected projects, operating simultaneously to deliver refined commodities.

• Geology is the study of the earth’s crust and its rock formation and include classifying and mapping of the composition and distribution of mineral deposits contained in the earth’s formation.

• In Mining Industry, this knowledge is applied to find mineral resources and to upgrade existing resources.

• Geology has the vital role in Mining Industry. It helps to locate deposit of important minerals and determine whether the quantities are large enough to make mining economically viable and to ensure that the minerals are efficiently extracted from the deposit for maximum profit.

• Typical work activities of geology in mining industry are include: mapping, sampling, recording and compiling, interpreting, modeling, presenting and reporting geological data in and around mine; checking quality levels of material produce for reserve assessment, classifying resource, assessing geo-techniques, and updating detailed database, etc.

POWERED BY COPPERSTAGE OF A MINING

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MINERAL RESOURCE-RESERVE CLASSIFICATION

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GRASBERGINTRUSIVE

ERTSBERGINTRUSIVE

MILL

LEMBAHTEMBAGA

KUCINGLIAR

BIGGOSSAN

GRASBERGOPEN PIT

EESS

DOM

0 2000METERS

A

B

COW “ A” GEOLOGY and DEPOSITS LOCATION

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9

RESERVES 2017 – RESERVES STATEMENT January 22nd 2018

Deep Ore Zone Reserve 78,761 kt

Cu 0.54 %

Au 0.76 g/t

Ag 2.05 g/t Total Draw Points:

1,352

Deep Mill Level Zone Reserve 437,043 kt

Cu 0.91 % Au 0.76 g/t

Ag 4.39 g/t Total Draw Points:

1,488

Big Gossan Reserve 57,971 kt

Cu 2.22 %

Au 0.93 g/t

Ag 13.18 g/t

Kucing Liar Reserve 359,883 kt

Cu 1.25 %

Au 1.07 g/t

Ag 6.48 g/t

Grassberg Block Cave Reserve: 963,474 kt

Cu 1.01 %

Au 0.72 g/t Ag 3.52 g/t

Total Draw Points: 2,412

Grasberg Open Pit: Reserve 33,257 kt

Cu 1.29 %

Au 2.64 g/t

Ag 3.63 g/t

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Role of Geology in Underground Mine (PT. Freeport Indonesia)

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Geo Engineering

Surface GeoEngineering

Geo Data Management and Regional Modeling

Civil Geotech and Regional Hydrology

UG GeoEngineering

Geo Engineering SHE

GEO-ENGINEERING DIVISION

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UG GEO-ENGINEERING DEPARTMENT

UG Geo Engineering

UG Monitoring

UG HydrologyUG QA/QC

UG Geotech

UG Geology

POWERED BY COPPERUG MINE GEOLOGY’S TASKS

POWERED BY COPPERUG MINE GEOLOGY’S TASKS

POWERED BY COPPERCOW “ A” STRATIGRAPHY

Regional Model Will be used as Reference map on UG Geology Drift Mapping

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Grasberg Fault

MidGrasberg Fault

Kali Fault

CV Fault

(Tf) Faumai Limestone

(Tw) Waripi Dolomite

HSZ

GIC Intrusion

(Tsk)South Kali Diorite

Actual Opening Drift

Plan Drift

GBC RESERVES 2017 – PB2

Block Model: cowamodel_1801.bmf

GBC RESERVES 2017 – PB1

16

Geology and Mine Design GBC 2830L Extraction Level – Reference Map

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17

Geology With Mine Layout DMLZ Extraction Level – Reference Map


A’

SKARN

A


(Te) Ertsberg Diorite

DMLZ RESERVES 2016

Cros

s Se

ctio

n Li

ne

CV Fault

Erts1 Fault

Conc F

ault

South Fault

West Fault

Guru

Faul

t

(Kkel) Kembelangan Limestone

(Kkes) Kembelangan Sandstone

Actual Opening Drift

Plan Drift

POWERED BY COPPERGEOLOGICAL ASSESSMENT and APPROVAL

Task:Underground Geology must do geological assessment before being able to give approval for Underground operations to proceed with the drift-infrastructure advances. Underground Mine Geologist support this program by checking for potential weak zones caused by structures, lithology-material types and water occurrences.

Value:Geological assessments and correct recommendations / approvals will have a direct impact on the economics of the UG operation. Wrongly given recommendations on the expected geology behind the drift-infrastructure headings can have great impact on safety matters.

Types :POI – Points Of IntentWorksheet ApprovalDrilling Approval

POWERED BY COPPERGBC Plan Of Intent

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POWERED BY COPPERGBC- WORKSHEET APPROVAL

POWERED BY COPPERGEOLOGICAL ASSESSMENT and APPROVAL

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UG Drift/Heading/Shaft Mapping

Underground Geology in daily basis is assigned to traversed and mapped all new exposures. Daily mapping provides the distribution and boundaries of lithology, structures, material/rock type, veins and water occurrences. All the mapping data is daily updated in the Vulcan Underground Mapping System (UMS) and transferred to the acQuire database system.

Factual mapping data are used for Geological and Structural interpretation and will be used for modelling update.

GEOLOGICAL DATA COLLECTION

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DATA ENTRY AND PLOTINGVULCAN UMS DATABASE SYSTEM

UMS Vulcan Structures Data

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DATA ENTRY AND PLOTINGAcquire Geology Mapping Database

Geology Mapping result used for Geotech Parameter Calculation (RQD, RMR, Q and Rock hardness for support recommendation

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UMS – DMLZ Factual Lithology and Interpretation

POWERED BY COPPERGEOLOGICAL DATA COLLECTION

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Task:Underground Mine Geology biweekly advises the DOZ Operational on the lithology, rock types and sticky-clay percentage, fragmentation and moist/water content in the DOZ drawpoints to update drawpoints class.

Underground Mine Geology daily advise the Big Gossan Operational Group on the volume percent of rock-type pyrite, pyrrhotite, clay, iron-oxide, sulfur and skarn types in the planned stope areas.

Value:Drawpoints class and their changes will drive the daily draw order in DOZ mine production plan in-term of short term and long term strategic planning. BG daily UMG Ore Control checks lithology and material types at stope areas.

This is function of Grade Control Role’s

Drawpoint/Stope Mapping


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P08

DOZ Dominant and Single Rock Type Distribution

POWERED BY COPPERDrawpoint Mapping

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Task:Underground Mine Geology conducts on all drift, x/c openings channel sampling on the left, and right rib. Channel survey is divided into 3m rounds and sample composites of those rounds are assayed. The 3m rounds are also described on lithology, rock type and mineralogy, and structures.Underground Mine Geology do sampling in the drawpoints to do QA/QC on the Drawpoint Sampling Procedure and for wetmuck mineralogical analysis.

Value:Channel sampling is an equivalent of a drill hole. Channel sampling combined with mapping of the drift, x/c openings give a detailed information of the ore-waste classification of that areas; and have therefore direct impact on the economics of the UG operations.

Grade control Sampling need to follow the sampling procedure to give proper representative mine frequency, samples weight and protocol.


Channel and Drawpoint Sampling

POWERED BY COPPEREqCu Channel Database Vs EqCu Block Model

at DMLZ 2590L

POWERED BY COPPERGrade Distribution and Variance

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Task:Underground Mine Geology manages three to four diamond core drilling rigs (Geology, Grade Control and Metallurgical drilling). Create drilling plans that gives information on the planned drift, stratigraphy, lithology, geotechnical and material types and structures behind the drift heading. Prepare drill sites, quick log the core and assist the Hydrology, Geotech and other Group by logging their drill cores. Underground Mine Geology also validates the detailed geology-geotechnical logging and assay data from the Timika Core Logging Group.

Value:Rapidly logging core at drill stations or at the core-shed provide information necessary to make drilling decisions and daily reports. The data collected is partly intended to be a substitute for detailed core logging. Diamond Drilling gives information on the lithologies, structures, geotechnical and material types behind the drift-heading and give inside on the geological situation at the planned drift-infrastructures. Assay data from the core also gives information for the Resource Model.


Diamond Core Drilling

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GV

D1-

01-0

1

GV

D1

-04-

01

GV

D3-

01-0

1

GVD1A-10-02

GVD Pilot Hole Drilling

GVD1-01-01

Section view NW along GVD1-01-01

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KL20 series

Kucing Liar Exploration Drilling

EXPLORATION DRIFT

XC#16

EX

PL

OR

AT

ION

DR

IFT

XC#16

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TE02-24

TE02

-24

DMLZ Infill Drilling

Section view NW along TE02-24

DZ 2590L

TE02-23

TE02-22

TE02-2

1

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Big Gossan Delination DrillingSection along DDH BG241E-01

BG241E-01

BG241E-02

bg_august_2014_final.bmf

BG241E-01

POWERED BY COPPERBig Gossan Grade Control Drilling

A

A’

STOPE

STOPE

STOPE

POWERED BY COPPERKUCING LIAR METALLURGI DRILLING

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Rapidly logging core at drill stations or at the core-shed provide information necessary to make drilling decisions and daily reports. The data collected is partly intended to be a substitute for detailed core logging. Diamond Drilling gives information on the lithologies, structures, geotechnical and material types behind the drift-heading and give inside on the geological situation at the planned drift-infrastructures. Assay data from the core also gives information for the Resource Model. .

QUICK LOGGING

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TaskInput and plot daily mapping data Vulcan GeoEngineering and Underground Mapping System and submit the data to GDM Group to imported to Acquire database. Do routine QA/QC on the data.

Input Drawpoint mapping data and import grade and tonnage from cave management group to UG Geology MS Access production data base for future use. Do routine QA/QC on the data.

Value:The proper and valid data is important for analysis which used for the next step of works or recommendation and to make a strategic decision. “Garbage in-garbage out”.

Data recording and QA/QC

POWERED BY COPPERMODELLING

Task:Interpretation of the following data, lithology, alteration, rock types and structure is done on a daily basis. Polygons are created and edited in the Vulcan Underground Mapping System (UMS) on a drift-plan level 2D basis, using Vulcan software. 3D triangulation models are created from the 2D Interpretation and combination of drill core data. Vulcan software is used.

Short Range Resource, Grade Control, Mineralogy, Geotech and ARD Block Model are assigned to UG Geology to produce in Quarterly basis. Those model are use for short and medium term recommendation or planning decision.

Value:Validated of Geological model depend on validated of the data used.

3D Triangulation and Block Model

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BIG GOSSAN 3D GEOLOGY TRIANGULATION MODEL

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46

DMLZ – NW CROSS SECTION A-A’ EESS Skarn

(Tk) Kais Limestone

A

(Tf) Faumai Limestone


(Te) Ertsberg Diorite

DMLZ RESERVES 2016

A’

(Ts) Sirga Sandstone

Erts1 Fault

South Fault

Erts3

Fau

lt

Erts2

Fau

lt

DMLZ 2590L Footprint Overview

EESS Skarn

EESS Skarn

CV

Fau

lt

Index Map


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Exploratory Data Analysis

47

Cu - Box Plot of DDH sample inside est. domain

2101

6401

6402

664

1

6642

667

1

6672

770

777

(reference: BG_2010_Resources Report.doc)

Raw DDH statistic (Big Gossan)

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Resources Estimation

Resource estimation conducted using Ordinary Kriging (OK) method, with project limits, reflecting local mineralization controls. The BG deposit was estimated with localized continuity trends, variograms, estimation parameters and broader overlap of drilling data

Block Model Description (Big Gossan)

Estimation Domains (Big Gossan)

Rock Code

Inside Min_zone code

Outside Min_Zone code

Domain description Vulcan Code calculated from the following solids

Tw 6401 6402 Waripi Dolomite/Limestone bg_minzone_2010.00t and Tw*09.00t

Kkel + Kkeh

6641 6642 Ekmai limestone and shale

bg_minzone_2010.00t and kkel*09.00t and kkeh*09.00t

Kkes 6671 6672 Ekmai sandstone bg_minzone_2010.00t and kkes*09.00t

Breccia 2101 Hydrothermal Breccia Hydrothermal_bx *09.00t

Diorite 770 Diorite Dyke Diorite*09.00t

ALL Others 777 Other

Limstones/Sandstones tf, tk1, ts geo 09.00t

The details of the estimation domains establishment for Big Gossan shown on table below. The areas outside mineralized created solids are represented by lithologic subdivision into none or weak mineralized zones.

6402

2101664

1

6671

6672

6401

6642

770

The 2975m plan with estimation domain block and DDH


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49

Exploratory Data Analysis

Variogram analysis (Big Gossan)Spatial continuities, in the form of pair-wise-relative models were assessed along different directions and at different dip angles in each estimation domain for copper, gold and silver. To estimate the nugget effect, true down-hole pair-wise-relative variograms were computed. The grade spatial continuities were analyzed using Snowden Supervisor software and February 2010 5m composited drill holes data.


Varigraphy of domain 6401 – (Tw) Waripi mineralized

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bg_SRM_2350-3060_1408.bmf

EqCu Block Model at BG 2600 L

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GBC MINERALOGY BLOCK MODELPlain View Map at GBC Undercut Level 2850L, Windows 20M

Geotech CaveQuarter-2 2016

GBC SOFTZONE 1707

Potassic

Phyllic

HSZ

SE

2 Fa

ult

SE

11 Fa

ult

SE3 C

on

f1 Fa

ult

NE2K Faul

t

gbc_min_DDH_0717.bmf

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EESS-GBC Dev Plan Overlain with 2017 ARD Block Model

GBC-EESS ARD Block Model Sept 2017

• Released 10K block model using CNV to indicate PAF area

• Based on sample analysis result from Timika Environmental Lab (TEL) indicates that PAF area were at contact (Te) Ertsberg Diorite and Fault area therefore 25m buffer applied.

• Almost all block have CNV value as default values assigned for C% value

PAF: Potentially Acid FormingNAF: Non Acid Forming

POWERED BY COPPERSTOPE NOTE

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B

A

CD

STOPE RECONCILIATION

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Plan STOPE

A

CPASTE

A = filled_2560_11_17_cms20130111.00tB = filled_2560_13_17_cms20121202.00tC = filled_2540_11_18_cms20111028.00tD = 2540_12_17_act.00tE= filled_2540_13_18_cms20111028.00t

B

D

E

CMS STOPE 2560_12_17

STOPE 2560_12_17

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Actual Development

Plan Stope

Actual Stope

Overbreak

Underbreak

STOPE RECONCILIATION

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MS ACCESSSTOPE RECONCILIATION

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UNDERGROUND MINE GEOLOGY