EX-99.1 2 d325229dex991.htm EX-99.1 EX-99.1

Exhibit 99.1

 

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BARRICK GOLD CORPORATION

TECHNICAL REPORT ON THE

ZALDÍVAR MINE, REGION II, CHILE

NI 43-101 Report

Qualified Persons:

Luke Evans, P.Eng.

Richard J. Lambert, P.E.

March 16, 2012

ROSCOE POSTLE ASSOCIATES INC.


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Report Control Form

 

Document Title

   Technical Report on the Zaldívar Mine, Region II, Chile

Client Name & Address

  

Barrick Gold Corporation

Brookfield Place, TD Canada Trust Tower

Suite 3700, 161 Bay Street, P.O. Box 212

Toronto, Ontario

M5J 2S1

Document Reference

   Project #1683    Status &

Issue No.

   Final

Version

   Rev 0

Issue Date

   March 16, 2012   

Lead Author

  

Luke Evans, P.Eng.

Richard J. Lambert, P.E.

   (Signed)

(Signed)

Peer Reviewer

   Deborah A. McCombe, P.Geo.    (Signed)

Project Manager Approval

   Luke Evans, P.Eng.    (Signed)

Project Director Approval

   Graham G. Clow, P.Eng.    (Signed)

Report Distribution

   Name    No. of Copies
   Client   
   RPA Filing    1 (project box)

 

Roscoe Postle Associates Inc.

55 University Avenue, Suite 501

Toronto, Ontario M5J 2H7

Canada

Tel: +1 416 947 0907

Fax: +1 416 947 0395

mining@rpacan.com


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TABLE OF CONTENTS

 

     PAGE  

1 SUMMARY

     1-1   

Executive Summary

     1-1   

Technical Summary

     1-5   

2 INTRODUCTION

     2-1   

3 RELIANCE ON OTHER EXPERTS

     3-1   

4 PROPERTY DESCRIPTION AND LOCATION

     4-1   

5 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY

     5-1   

6 HISTORY

     6-1   

Exploration and Ownership History

     6-1   

Production History

     6-1   

7 GEOLOGICAL SETTING AND MINERALIZATION

     7-1   

Regional Geology

     7-1   

Local and Property Geology

     7-3   

Alteration

     7-5   

Mineralization

     7-6   

8 DEPOSIT TYPES

     8-1   

9 EXPLORATION

     9-1   

Exploration Potential

     9-1   

10 DRILLING

     10-1   

11 SAMPLE PREPARATION, ANALYSES AND SECURITY

     11-1   

Sampling Method and Approach

     11-1   

Sample Preparation, Analyses and Security

     11-1   

12 DATA VERIFICATION

     12-1   

13 MINERAL PROCESSING AND METALLURGICAL TESTING

     13-1   

Metallurgical Testing

     13-1   

14 MINERAL RESOURCE ESTIMATE

     14-1   

Summary

     14-1   

Geological Models

     14-2   

Geological Domains

     14-7   

Density Data

     14-8   

Cut-Off Grades

     14-8   

Capping of High Grade Values

     14-8   

Composites

     14-9   

Contact Plot Analysis

     14-12   

Variography

     14-15   

 

 

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Resource Estimation Methodology

     14-17   

Resource Estimate Validation

     14-20   

Resource Classification

     14-21   

15 MINERAL RESERVE ESTIMATE

     15-1   

16 MINING METHODS

     16-1   

Production Schedule

     16-7   

Waste Rock

     16-8   

Mine Equipment

     16-8   

Mine Infrastucture

     16-9   

17 RECOVERY METHODS

     17-1   

Ore Processing

     17-1   

Dynamic Pad Leach Process

     17-2   

ROM Leach Pad

     17-2   

SX/EW Copper Recovery Circuit

     17-2   

Flotation Concentration Process

     17-2   

Copper Recovery

     17-4   

Copper Recovery Algorithms at Zaldívar

     17-4   

2011 Recovery Model

     17-8   

18 PROJECT INFRASTRUCTURE

     18-1   

19 MARKET STUDIES AND CONTRACTS

     19-1   

Markets

     19-1   

Contracts

     19-1   

20 ENVIRONMENTAL STUDIES, PERMITTING, AND SOCIAL OR COMMUNITY IMPACT

     20-1   

Environmental Studies

     20-1   

Project Permitting

     20-1   

Social or Community Requirements

     20-2   

Mine Closure Requirements

     20-2   

21 CAPITAL AND OPERATING COSTS

     21-1   

Capital Costs

     21-1   

Operating Costs

     21-2   

Manpower

     21-3   

22 ECONOMIC ANALYSIS

     22-1   

23 ADJACENT PROPERTIES

     23-1   

24 OTHER RELEVANT DATA AND INFORMATION

     24-1   

25 INTERPRETATION AND CONCLUSIONS

     25-1   

26 RECOMMENDATIONS

     26-1   

27 REFERENCES

     27-1   

28 DATE AND SIGNATURE PAGE

     28-1   

29 CERTIFICATE OF QUALIFIED PERSON

     29-1   

 

 

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LIST OF TABLES

 

     PAGE  

Table 1-1 Mineral Resources – December 31, 2011

     1-1   

Table 1-2 Mineral Reserves – December 31, 2011

     1-2   

Table 4-1 Exploitation Concessions

     4-1   

Table 6-1 Zaldívar Production – 2007-2011

     6-3   

Table 10-1 Drilling Summary

     10-2   

Table 11-1 QC Insertion Rates

     11-2   

Table 14-1 Mineral Resources – December 31, 2011

     14-1   

Table 14-2 Geological Estimation UGE Codes and Descriptions

     14-7   

Table 14-3 Tonnage Factors

     14-8   

Table 14-4 TCU Capping Levels

     14-9   

Table 14-5 ASCu Capping Levels

     14-9   

Table 14-6 TCU Composite Statistics By Geological Domain (UGE)

     14-11   

Table 14-7 %TCu Variogram Parameters

     14-15   

Table 14-8 %TCu Estimation Search Ellipse Parameters

     14-19   

Table 15-1 Mineral Reserves – December 31, 2011

     15-1   

Table 16-1 Mine Design Parameters

     16-4   

Table 16-2 Mine Production Schedule

     16-7   

Table 16-3 Mine Equipment Fleet

     16-9   

Table 17-1 Metallurgical Model Algorithms

     17-8   

Table 21-1 Capital Costs

     21-1   

Table 21-2 Mine Operating Costs

     21-2   

Table 21-3 Unit Process Operating Costs

     21-2   

Table 21-4 G&A Costs

     21-3   

Table 21-5 Manpower

     21-3   

LIST OF FIGURES

 

     PAGE  

Figure 4-1 Location Map

     4-3   

Figure 4-2 Zaldívar Exploitation Boundary

     4-4   

Figure 4-3 Mining Concession Boundary and Surface Rights

     4-5   

Figure 7-1 Regional Geology

     7-2   

Figure 7-2 Property Geology

     7-4   

Figure 7-3 Mineralization Section

     7-8   

Figure 10-1 Drill Plan

     10-4   

Figure 14-1 Lithology Zones

     14-4   

Figure 14-2 Alteration Zones

     14-5   

Figure 14-3 Mineralization Zones

     14-6   

Figure 14-4 Frequency Distribution of TCu Composites Versus Raw Sample Data

     14-10   

Figure 14-5 Boxplot of TCu Composites for Each UGE

     14-11   

Figure 14-6 Contact Plot Analysis of TCu for Leached and Oxide Domains

     14-13   

Figure 14-7 Contact Plot Analysis of ASCu for Leached and Oxide Domains

     14-13   

Figure 14-8 Semi-Soft and Semi-Hard Boundary Weights

     14-14   

Figure 14-9 TCu Correlogram Models for UGE 3

     14-16   

 

 

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Figure 14-10 TCu Correlogram Models for UGE 7

     14-17   

Figure 14-11 TCu Blocks and Assays—Section 22,000N

     14-20   

Figure 14-12 Swath Plots

     14-21   

Figure 14-13 TCu Correlogram for UGE 7

     14-23   

Figure 16-1 Zaldívar Mine Phases

     16-2   

Figure 16-2 Ultimate Pit Design

     16-5   

Figure 16-3 Pit Slope Design Sectors

     16-6   

Figure 17-1 Process Flow Sheet

     17-3   

Figure 17-2 ASCu Recovery vs. ASCu Head Grade

     17-5   

Figure 17-3 SCu Recovery vs. SCu Head Grade

     17-6   

Figure 17-4 Metallurgical Recovery Model Curves

     17-9   

Figure 18-1 Site Infrastructure

     18-3   

 

 

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1 SUMMARY

EXECUTIVE SUMMARY

Roscoe Postle Associates Inc. (RPA) was retained by Barrick Gold Corporation (Barrick) to prepare an independent Technical Report on the Zaldívar copper operation (the Project), located in northern Chile. The purpose of this report is to support public disclosure of Mineral Resource and Mineral Reserve estimates at the Project as of December 31, 2011. This Technical Report conforms to National Instrument 43-101 (NI 43-101) Standards of Disclosure for Mineral Projects. RPA visited the Zaldívar Mine on October 24 to 27, 2011.

The Zaldívar Mine is managed and operated by Compañía Minera Zaldívar Ltda. (CMZ), which is 100% owned by Barrick. Zaldívar is a large scale open pit operation utilizing a traditional truck and shovel fleet. Mining is carried out from one open pit at a rate of 83 million tonnes per annum (Mtpa), consisting of 22 Mtpa of crushed ore, 15 Mtpa of dump leach ore, and 46 Mtpa of waste. The ultimate pit will measure approximately 2.8 km east to west, 2.6 km north to south, and have an average depth of approximately 630 m. A total of 578 million tonnes grading 0.52% Cu representing 6.6 billion pounds of contained copper and 3.8 billion pounds of recoverable copper is projected to be produced between 2012 and 2028.

Table 1-1 summarizes open pit Mineral Resources exclusive of Mineral Reserves as of December 31, 2011.

TABLE 1-1 MINERAL RESOURCES – DECEMBER 31, 2011

Barrick Gold Corporation – Zaldívar Mine

 

Category

   Tonnage
(Mt)
     Grade
(% Cu)
     Contained
Metal

(Mlb Cu)
 

Measured

     71.3         0.432         679.5   

Indicated

     53.5         0.462         545.5   
  

 

 

    

 

 

    

 

 

 

Total Measured and Indicated

     124.8         0.445         1,225.0   

Inferred

     37         0.54         439   

Notes:

1. CIM definitions were followed for Mineral Resources.
2. Mineral Resources are estimated based on a profit model using a copper price of US$3.25 per pound and a CLP/US$ exchange rate of 500.
3. Mineral Resources are exclusive of Mineral Reserves.
4. Numbers may not add due to rounding.

 

 

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Table 1-2 summarizes the Zaldívar end of year 2011 (EOY2011) Mineral Reserve estimate.

TABLE 1-2 MINERAL RESERVES – DECEMBER 31, 2011

Barrick Gold Corporation – Zaldívar Mine

 

Category

   Tonnage
(Mt)
     Cu (%)      Contained Metal
(Mlb Cu).
 

Proven

     386.3         0.528         4,496.5   

Probable

     191.7         0.498         2,105.5   
  

 

 

    

 

 

    

 

 

 

Proven & Probable

     578.0         0.518         6,602.0   

Notes:

1. CIM definitions were followed for Mineral Reserves.
2. Mineral Reserves are estimated at a variable cut-off grade.
3. Mineral Reserves are estimated using an average long-term copper price of US$2.75 per pound and a CLP/US$ exchange rate of 500.
4. Numbers may not add due to rounding.

CONCLUSIONS

RPA offers the following conclusions:

GEOLOGY AND MINERAL RESOURCE ESTIMATION

 

   

The EOY2011 Measured and Indicated Mineral Resource is 125 million tonnes at a total copper grade of 0.445% containing 1.225 billion pounds of copper. The Mineral Resources are exclusive of Mineral Reserves.

 

   

The EOY2011 Inferred Mineral Resource is 37 million tonnes at a total copper grade of 0.54% containing 439 million pounds of copper.

 

   

Mineral Resource estimates have been prepared utilizing acceptable estimation methodologies. The classification of Measured, Indicated, and Inferred Resources, stated in Table 1-1, meet the requirements of NI 43-101 and CIM Definition Standards for Mineral Resources and Mineral Reserves dated November 27, 2010 (CIM definitions).

 

   

The methods and procedures utilized by CMZ at the Zaldívar Mine to gather geological, geotechnical, assaying, density, and other information are reasonable and meet generally accepted industry standards. Standard operating protocols are well documented and updated on a regular basis for most of the common tasks. CMZ carries out regular comparisons with blasthole data, previous models, and production reconciliation results to calibrate and improve the resource modelling procedures.

 

   

The current drill hole database is reasonable for supporting a resource model for use in Mineral Resource and Mineral Reserve estimation.

 

 

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CMZ has conducted the exploration and development sampling and analysis programs using standard practices, providing generally reasonable results. The resulting data can effectively be used for the estimation of Mineral Resources and Mineral Reserves.

 

   

Overall, RPA is of the opinion that CMZ has done very high quality work that exceeds industry practice.

MINING AND MINERAL RESERVES

 

   

The EOY2011 Proven and Probable Mineral Reserves are 578 million tonnes at a total copper grade of 0.518% containing 6.602 billion pounds of copper.

 

   

The Mineral Reserve estimates have been prepared utilizing acceptable estimation methodologies and the classification of Proven and Probable Reserves, stated in Table 1-2, conform to CIM definitions.

 

   

The operating data provided by CMZ and the supporting documents were prepared using standard industry practices and provide reasonable results and conclusions.

 

   

Standard operating protocols are well documented and updated on a regular basis for most of the common tasks.

 

   

Recovery and cost estimates are based upon operating data and engineering to support a Mineral Reserve statement. Economic analysis using these estimates generates a positive cash flow, which supports a statement of Mineral Reserves.

 

   

The current Zaldívar Life of Mine (LOM) plan provides reasonable results and, in RPA’s opinion, meets the requirements for statement of Mineral Reserves. In addition to the Mineral Reserves in the LOM plan, there are Mineral Resources and potential sulphide resources that represent opportunities for the future.

PROCESSING

 

   

The process includes heap leaching with copper recovery in a solvent extraction/electrowinning (SX/EW) process in the form of copper cathode.

 

   

RPA has reviewed the recovery model and finds the development of the recovery formulas and the reconciliation to historic data to be reasonable. The metallurgical testwork, which supports the models, is also reasonable and adequate.

 

   

In 2012, a revision will be made to the recovery model. The revised recovery model will account for the current operational parameters and results.

ENVIRONMENTAL CONSIDERATIONS

 

   

The Project has approximately 140 active permits. All permits are in good standing and there is an extensive environmental monitoring program to ensure compliance with the requirements of these permits.

 

 

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RECOMMENDATIONS

The Zaldívar LOM plan provides reasonable results and, in RPA’s opinion, meets the requirements for statement of Mineral Reserves. This Technical Report is based on the LOM plan. In addition to the LOM plan, there are additional resources and potential resources that should be given further consideration in the future. Below is a list of recommendations to consider:

MINING

 

   

The LOM plan is robust and Barrick should proceed to implement the plan as presented.

 

   

There is a known primary sulphide resource below the current Proven plus Probable oxide and secondary sulphide reserves. Additional work to drill these resources and develop a Feasibility Study for the primary sulphide should also proceed.

ENVIRONMENTAL CONSIDERATIONS

 

   

Evaluation of permit requirements, developing baseline studies, and starting a new Environmental Impact Assessment (EIA) for the sulphide project should proceed in unison with the primary sulphide feasibility study.

ECONOMIC ANALYSIS

RPA has performed an economic analysis of the Zaldívar Mine using the estimates presented in this report and confirms that the outcome is a positive cash flow that supports the statement of Mineral Reserves.

 

 

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TECHNICAL SUMMARY

PROPERTY DESCRIPTION AND LOCATION

Zaldívar is located in the Andean Precordillera in Region II of northern Chile, approximately 1,400 km north of Santiago and 196 km southeast of the city of Antofagasta, a deepwater port with bulk loading and unloading facilities. Zaldívar is connected to Antofagasta by a paved highway as well as the Antofagasta Salta narrow-gauge railway. Antofagasta is served by national airlines, with several flights daily providing a link to Santiago and other major centres. The mine is located at an altitude of 3,200 m.

LAND TENURE

The Zaldívar mineral rights boundary is defined by ten overlapping exploitation concessions that have a combined area of approximately 1,295 ha. The mine is managed and operated by CMZ, which is 100% owned by Barrick through its acquisition of Placer on March 3, 2006. There are no royalties payable. Zaldívar is surrounded by concessions owned by Minera Escondida Limitada (MEL). CMZ has a number of easement or surface rights agreements with MEL. MEL has authorized CMZ to build infrastructure such as heap leach pads, the SX/EW plant, tailings and other facilities within the area covered by the MEL concessions.

EXISTING INFRASTRUCTURE

The Project infrastructure and services have been designed to support an operation of 65,000 tpd of ore to dynamic heap leach processing and a nominal 240,000 tpd of total material mined.

The existing infrastructure includes:

 

   

Mine camp facilities sufficient for the current Zaldívar workforce of 863 people and the 1,146 contractors and consultants.

 

   

A private two-lane paved road, shared by three major mines, Zaldívar, Escondida, and El Peñón, that leads to the Zaldívar camp and offices.

 

   

Mine and heap leach facilities and an SX/EW plant located at the mine site.

 

   

On-site facilities, including safety/security/first aid/emergency response building, assay laboratory, plant guard house, dining facilities, and offices.

 

 

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Related mine services facilities (truckshop, truck wash facility, warehouse, fuel storage and distribution facilities, reagent storage and distribution facilities) and other services facilities to support operations.

 

   

Process water supplied from groundwater at Negrillar, 130 km east of Zaldívar.

 

   

Rail service that transports sulphuric acid to the mine and copper cathode to the port of Antofagasta.

 

   

A dual-circuit, 220 kV, 230 km long transmission line.

HISTORY

The Zaldívar deposit was discovered in 1979 and exploration drilling was carried out in 1981-1984. In 1989, the mining rights were sold to Sociedad Minera La Cascada Limitada, which in November 1989 transferred them to Outokumpu under a sales contract with Outokumpu Resources (Services) Limited. In December 1992, Outokumpu announced the formation of a 50/50 joint venture with Placer, at which time a joint venture company, CMZ, was formed.

In November 1995, commercial production started. The capital cost of the Project was at approximately $600 million. In December 1999, Placer acquired Outokumpu’s 50% interest in CMZ. In March 2006, Barrick acquired Placer and became owner of the Project.

GEOLOGY AND MINERALIZATION

The Zaldívar porphyry copper deposit is situated on the western margin of the Atacama Plateau in northern Chile. The deposit is part of a large Tertiary porphyry copper system that also includes the Escondida porphyry copper deposit. This porphyry complex occurs within the West Fissure structural system, a major regional feature that has controlled the emplacement of some of the largest porphyry copper deposits in northern Chile. The West Fissure system extends for approximately 1,000 km and separates Paleozoic rocks to the east from Mesozoic and Paleocene rocks to the west.

The Zaldívar deposit occurs at the intersection of three major sets of faults striking north-south, northwest-southeast, and northeast-southwest. This structural setting has controlled the emplacement of the intrusives and hypogene mineralization as well as leaching and secondary enrichment.

 

 

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There are three main lithologic units at Zaldívar: the Zaldívar porphyry, the andesite unit, and the Llamo porphyry.

Most of the copper at Zaldívar occurs in a blanket of oxide and secondary sulphide mineralization that overlies deeper primary sulphide mineralization. The oxide mineralization mostly occurs in the andesite unit, whereas the secondary sulphide mineralization generally occurs in the Zaldívar porphyry. The most economically important mineralization types are secondary sulphide (chalcocite) and oxide (brochantite and chrysocolla). CMZ is currently investigating the economic potential of the primary sulphide mineralization, which consists of pyrite, chalcopyrite, bornite, and molybdenite.

EXPLORATION POTENTIAL

Zaldívar is a mature operation with a relatively small mining concession area. The major exploration programs took place prior to the completion of the feasibility study in 1993. A major drilling campaign was completed in 2000 to define the limits of the deposit within the mining concessions. That campaign marked the end of exploration activity targeting oxide mineralization at Zaldívar. More recently, deep drilling campaigns have targeted the underlying sulphide mineralization, Zaldívar Deeps Sulphide Cu-Mo-Au-Ag Project.

CMZ built a new block model for this primary sulphide mineralization as part of the 2010 mid-year update. There appears to be sufficient drill holes and technical studies completed to demonstrate that the mineralization meets the requirement for “reasonable prospects for economic extraction”.

MINERAL RESOURCES

The EOY 2011 open pit Mineral Resources exclusive of Mineral Reserves as stated in Table 1-1 include a Measured and Indicated Mineral Resource of 124.8 million tonnes grading 0.445% Cu containing 1.255 billion pounds of copper and an Inferred Mineral Resource of 37 million tonnes grading 0.54% Cu containing 439 million pounds of copper. The resource model was prepared by Barrick Senior Resource Geologist Cristian Monroy under the supervision of Barrick Superintendent of Resource and Reserve Modelling Benjamin Sanfurgo.

 

 

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RPA reviewed the resource assumptions, input parameters, geological interpretation, and block modelling procedures and is of the opinion that the Mineral Resource estimate is appropriate for the style of mineralization and that the resource model is reasonable and acceptable to support the EOY2011 Mineral Resource and Mineral Reserve estimates.

RPA is not aware of any environmental, permitting, legal, title, taxation, socio-economic, marketing, political, or other issues that could materially affect the Mineral Resource and Mineral Reserve estimates.

MINERAL RESERVES

RPA reviewed the reported resources, production schedules, and cash flow analysis to determine if the resources meet the CIM definitions to be classified as reserves. Based on this review, it is RPA’s assessment that the Measured and Indicated Mineral Resource within the final pit design at Zaldívar can be classified as Proven and Probable Mineral Reserves.

The open pit reserves are estimated to be 578 million tonnes at 0.518% Cu, containing 6.602 billion pounds of copper and are classified as Proven and Probable Reserves as presented in Table 1-2.

MINING METHOD

The Zaldívar Mine is a traditional open pit truck/shovel operation. The open pit has seven phases remaining. The ultimate pit will measure approximately 2.8 km east to west, 2.6 km north to south, and have a maximum depth of approximately 630 m. Waste and ore are mined on 15 m benches.

The current mine life is from 2012 to 2028. Mine production is 83 Mtpa over the first eleven years and then decreasing thereafter. This includes a nominal 46 Mtpa of waste and is based only on mining and processing oxide and secondary sulphide ores. Metallurgical investigations are underway to evaluate further leaching of primary sulphide material and/or primary sulphide milling and flotation.

 

 

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There are three primary waste rock facilities, a heap leach facility, and a small tailings storage facility that handles tailings from the small flotation plant that processes fines from the primary heap leach crushing plant.

MINERAL PROCESSING

Processing is based on two heap leaching streams, one crushed and one ROM. Separation of the ore types is done by the mine department based on blasthole sample analysis. Primary processing is based on heap leaching a crushed material (80% passing 13 mm) utilizing a dynamic (on-off) heap leach facility. Additionally, marginal ores are processed through dump leaching at a ROM material size on a static pad. Pregnant solution from both leach pads is pumped to the SX/EW plant for metal extraction and production as copper cathodes. From the crushing circuit, 3% of the ore tonnage for the dynamic heap leach processing ends up in fines which are deposited in a sediment pond as a result of the washing system incorporated in the tertiary crushing system. These sediments are periodically processed through a small flotation plant and a copper concentrate is produced for sale.

The dynamic heap leach facility is based on a nominal 65,000 tpd operation (22 Mtpa). The ROM dump leach facility is based on the dynamic heap leach capacity and ore availability in the mine, and will average a nominal 15 Mtpa over the remaining mine life.

ENVIRONMENTAL, PERMITTING AND SOCIAL CONSIDERATIONS

The present operation of the Zaldívar Mine was approved in its original form called the “Zaldívar Project” in 1993 by the Comisión Regional del Medio Ambiente de la II Región de Antofagasta (COREMA). The project had, as its principal installation, an operating open pit mine, primary, secondary and tertiary crushing plants, a concentrating plant for fines, waste dumps, and tailings and a production line for copper cathodes that consists of a dynamic leach facility, ROM leach facility for low grade, and an SX/EW plant.

In 2009, an updated EIA was developed to optimize the mining processes and maintain production levels. The EIA was approved by COREMA in February 2010. On December 9, 2010, CMZ obtained its operational permits from the Servicio Nacional de Geología y Minería (SERNAGEOMIN) and expects to obtain other associated sectoral permits in due course.

 

 

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The Zaldívar Mine has approximately 140 active permits. All permits are in good standing. The mine runs an extensive environmental monitoring program to ensure compliance with the requirements of these permits. For the major environmental issues identified, management plans have been developed that include rehabilitation, site decommissioning, and closure.

Zaldívar operates under Barrick’s sustainability policy, which commits the operation to a corporate standard of environmental stewardship. This involves protecting human health, reducing the impact of mining on the ecosystem, and returning the site to a state compatible with a healthy environment. Zaldívar operates in an environmentally responsible manner with limited adverse impacts on the environment. Programs are in place that continuously monitor the process and surrounding areas and employ leak detection wells to detect any potential problems.

Mine closure plans are reviewed and analyzed annually. Current cost estimates for closure are $36.2 million.

CAPITAL AND OPERATING COST ESTIMATES

Remaining capital costs at Zaldívar are all primarily sustaining capital, which includes mine equipment replacement. Total remaining capital costs are a nominal $440 million. Mine prestripping capital of $193 million has been treated as an operating cost for the purposes of this Technical Report. Engineering studies for a primary sulphide flotation and process plant expansion are also included in the sustaining capital.

The Zaldívar Mine has been in production since November 1995. Operating costs are tracked and well understood. Mine operating costs are a nominal $1.47 per tonne of material mined or $3.12 per tonne of ore mined. Process operating costs are $7.35 per tonne ore processed and include the dynamic pad or heap leach and the dump leach, the crushing plant, acid, and all reagents. General and administrative costs (G&A) are $1.25 per tonne ore processed and include all management salaries, camp operating costs, and environmental, health and safety.

Zaldívar Mine site manpower is a nominal 2,000 people. Direct Zaldívar employees are only 863 with 1,146 contractors and consultants as of November 2011.

 

 

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2 INTRODUCTION

Roscoe Postle Associates Inc. (RPA) was retained by Barrick Gold Corporation (Barrick) to prepare an independent Technical Report on the Zaldívar copper operation (the Project), located in northern Chile. The purpose of this report is to support public disclosure of Mineral Resource and Mineral Reserve estimates at the Project as of December 31, 2011. This Technical Report conforms to NI 43-101 Standards of Disclosure for Mineral Projects.

Barrick is a Canadian publicly traded mining company with a large portfolio of operating mines and projects across five continents. Zaldívar is located in the Andean Precordillera in Region II of northern Chile, approximately 1,400 km north of Santiago and 196 km southeast of the city of Antofagasta.

The Zaldívar mining operation is managed and operated by Compañía Minera Zaldívar (CMZ), which is 100% owned by Barrick through its acquisition of Placer Dome Inc. (Placer) on March 3, 2006. There are no royalties payable. Zaldívar is surrounded by concessions owned by Minera Escondida Limitada (MEL). MEL has authorized CMZ to build infrastructure such as heap leach pads, the solution extraction/electrowinning (SX/EW) plant, and tailings facilities within the area covered by its mining concessions. MEL has begun mining the high walls that straddle the property boundary and stockpiling CMZ ore for CMZ.

Zaldívar is a large scale operation utilizing a traditional truck and shovel fleet. Mining is carried out from one open pit at a rate of 83 million tonnes per annum (Mtpa), consisting of 22 Mtpa of crushed ore, 15 Mtpa of dump leach ore, and 46 Mtpa of waste. The ultimate pit will measure approximately 2.8 km east to west, 2.6 km north to south, and have an average depth of approximately 630 m. A total of 578 million tonnes grading 0.52% Cu representing 6.6 billion pounds of contained copper and 3.8 billion pounds of recoverable copper is projected to be produced between 2012 and 2028.

 

 

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SOURCES OF INFORMATION

RPA Principal Geological Engineer Luke Evans, M.Sc., P.Eng., and RPA Principal Mining Engineer Richard J. Lambert, MBA., P.E., visited the property from October 24 to 27, 2011.

Discussions were held with the following Barrick personnel:

 

   

Leonardo González – General Manager of Operations

 

   

Eduardo Jofré – Technical Services Superintendent

 

   

Roberto Alfaro – Regional Superintendent of Long Range Mine Planning

 

   

Guillermo Albornoz – Chief Geotechnical Engineer

 

   

Eduardo Riveros – Chief Engineer

 

   

Mauricio Rubio – Chief Geologist

 

   

Norman Colón – Chief Metallurgist

 

   

Ramón Guajardo – Environmental Superintendent

 

   

Cristian Monroy – Senior Resource Geologist

 

   

Benjamin Sanfurgo – Superintendent of Resource and Reserve Modelling

 

   

Susy Solis –Geologist

 

   

Romina Ganga – Ore Control Geologist

 

   

Carolina Vera – Ore Control Geologist

 

   

Victor Diaz- Mine Laboratory Manager

 

   

Walter Hevia – Sample Preparation Shift Supervisor

 

   

Jorge Vega – Land Manager

 

   

Gregorio Olivares – Controller

 

   

Carolina Vasquez – Accountant (Capital costs)

 

   

Moises Bautista – Accountant (Operating costs)

The Zaldívar operation has been the subject of resource/reserve technical audits as follows:

 

   

March 2009, Mineral Reserve and Resource Audit, Scott Wilson Roscoe Postle Associates Inc. (Scott Wilson RPA, a predecessor company to RPA).

 

   

February 2007, Reserve Procedure Audit, Scott Wilson RPA.

 

   

December 2006, Level 2 Resource and Reserve Audit, Placer Dome Inc.

 

   

December 31, 2004, NI 43-101 Technical Report, AMEC Americas Limited (AMEC).

 

   

November 2004, Resource and Reserve Audit, Placer Dome Inc.

Mr. Evans is responsible for the overall preparation of this report. Mr. Evans reviewed the geology, sampling, assaying, and resource estimate work and is responsible for Items 1 to 12 and 14. Mr. Lambert reviewed the metallurgy, mining, reserve estimate,

 

 

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environment, and economics and is responsible for Items 13, and 15 to 26. RPA would like to acknowledge the excellent cooperation in the transmittal of data by Barrick personnel.

The documentation reviewed, and other sources of information, are listed at the end of this report in Section 27 References.

 

 

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LIST OF ABBREVIATIONS

Units of measurement used in this report conform to the metric system. All currency in this report is US dollars (US$) unless otherwise noted.

 

µ

   micron

°C

   degree Celsius

°F

   degree Fahrenheit

µg

   microgram

A

   ampere

a

   annum

bbl

   barrels

Btu

   British thermal units

C$

   Canadian dollars

cal

   calorie

cfm

   cubic feet per minute

cm

   centimetre

cm2

   square centimetre

d

   day

dia.

   diameter

dmt

   dry metric tonne

dwt

   dead-weight ton

ft

   foot

ft/s

   foot per second

ft2

   square foot

ft3

   cubic foot

g

   gram

G

   giga (billion)

Gal

   Imperial gallon

g/L

   gram per litre

g/t

   gram per tonne

gpm

   Imperial gallons per minute

gr/ft3

   grain per cubic foot

gr/m3

   grain per cubic metre

hr

   hour

ha

   hectare

hp

   horsepower

in

   inch

in2

   square inch

J

   joule

k

   kilo (thousand)

kcal

   kilocalorie

kg

   kilogram

km

   kilometre

km/h

   kilometre per hour

km2

   square kilometre
kPa    kilopascal
kVA    kilovolt-amperes
kW    kilowatt
kWh    kilowatt-hour
L    litre
L/s    litres per second
m    metre
M    mega (million)
m2    square metre
m3    cubic metre
min    minute
MASL    metres above sea level
mm    millimetre
mph    miles per hour
MVA    megavolt-amperes
MW    megawatt
MWh    megawatt-hour
m3/h    cubic metres per hour
opt, oz/st    ounce per short ton
oz    Troy ounce (31.1035g)
ppm    part per million
psia    pound per square inch absolute
psig    pound per square inch gauge
RL    relative elevation
s    second
st    short ton
stpa    short ton per year
stpd    short ton per day
t    metric tonne
tpa    metric tonne per year
tpd    metric tonne per day
US$    United States dollar
USg    United States gallon
USgpm    US gallon per minute
V    volt
W    watt
wmt    wet metric tonne
yd3    cubic yard
yr    year
 

 

 

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3 RELIANCE ON OTHER EXPERTS

This report has been prepared by Roscoe Postle Associates Inc. (RPA) for Barrick Gold Corporation (Barrick). The information, conclusions, opinions, and estimates contained herein are based on:

 

   

Information available to RPA at the time of preparation of this report,

 

   

Assumptions, conditions, and qualifications as set forth in this report, and

 

   

Data, reports, and other information supplied by Barrick and other third party sources.

For the purpose of this report, RPA has relied on ownership information provided by Barrick. RPA has not researched property title or mineral rights for the Zaldívar property and expresses no opinion as to the ownership status of the property.

RPA has relied on Barrick for guidance on applicable taxes, royalties, and other government levies or interests, applicable to revenue or income from Zaldívar.

Except for the purposes legislated under provincial securities laws, any use of this report by any third party is at that party’s sole risk.

 

 

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4 PROPERTY DESCRIPTION AND LOCATION

LOCATION

Zaldívar is located in the Andean Precordillera in Region II of northern Chile, approximately 1,400 km north of Santiago and 196 km southeast of the city of Antofagasta (Figures 4-1 and 4-2). Zaldívar is connected to Antofagasta by a paved highway as well as the Antofagasta Salta narrow-gauge railway. Antofagasta is a deepwater port with bulk loading and unloading facilities. The city is served by national airlines, with several flights daily providing a link to Santiago and other major centres. The mine is located at an altitude of 3,200 m.

LAND TENURE

Under Chilean regulations, the exploitation or mining concessions can be held indefinitely as long as the annual fees are paid to keep the permits in good standing. The exploitation concessions give the right to extract the ore and to sell the final products into the open market.

The Zaldívar mineral rights boundary is defined by combining ten overlapping exploitation concessions that have a total area of approximately 1,295 ha. The individual exploitation concessions are listed in Table 4-1 and the final official property boundary is shown in Figure 4-2.

 

TABLE 4-1 EXPLOITATION CONCESSIONS

Barrick Gold Corporation – Zaldívar Mine

 

Name

   Registration #      Area (ha)*  

Zaldívar 262/509

     02201-1168-7         1,240   

Ana 1/180

     02201-2489-4         180   

Antonia 1/191

     02201-2493-2         191   

Andrea 1/216

     02201-2492-4         216   

Aurora 1/201

     02201-2491-6         201   

Amanda 1/220

     02201-2490-8         220   

Angela 1/127

     02201-2488-6         127   

Berta 1/76

     02201-2494-0         76   

Rey 1/133

     02201-2563-7         262   

Reina 1/115

     02201-2564-5         172   

 

* Areas have considerable overlap, so total area is 1,295 ha.

 

 

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The Zaldívar mining operation is managed and operated by Compañía Minera Zaldívar (CMZ), which is 100% owned by Barrick through its acquisition of Placer Dome Inc. (Placer) on March 3, 2006. There are no royalties payable. Zaldívar is surrounded by concessions owned by Minera Escondida Limitada (MEL). CMZ has a number of easement or surface rights agreements with MEL. MEL has authorized CMZ to build infrastructure such as heap leach pads, the SX/EW plant, tailings and other facilities within the area covered by the MEL concessions. The current areas covered by surface rights agreements are shown in Figure 4-3, which also shows the locations of the mine, surface infrastructure, and mining concessions for the Zaldívar operations. MEL has begun mining the high walls that straddle the property boundary.

 

 

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5 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY

ACCESSIBILITY

Antofagasta is the Capital of Region II and is home to most employees at Zaldívar. Antofagasta has a population of 360,000 people (2009 census). There is daily commercial air service to Antofagasta from Santiago. There is a dirt airstrip at the Zaldívar mine site.

Access to the site is via a paved road from Antofagasta, following Highway 28 for 15 km to the southwest to the intersection with Route 5 (Pan-American Highway). From the intersection with Route 5, there is a private two-lane paved road that is shared by three major mines, Zaldívar, Escondida, and El Peñón, which heads to the east. It is 137 km to the Zaldívar turnoff. From the turnoff, it is seven kilometres to the Zaldívar camp and another eight kilometres to the Zaldívar mine offices. The total distance from Antofagasta is 170 km. Most consumables are transported along this route by truck.

The site is also serviced by rail with Ferrocarril Antofagasta—Bolivia (FCAB) transporting sulphuric acid to the mine and copper cathode to the port of Antofagasta.

CLIMATE

Zaldívar has an arid high desert climate. The mine lies 3,200 m above sea level. Temperatures range from -7°C in July to 22°C in January, with an average temperature of 10°C. Precipitation typically falls in the summer months, with 2 mm to 6 mm per annum. There is little precipitation and water from the area does not reach the sea.

Vegetation is almost absent and is restricted to areas with water accumulation, temporary runoff, or underground phreatic surfaces. Typical vegetation mostly consists of small flowering plants and cacti, such as oxalis hypsophila, cistanthe salsoloides, adesmia atacamensis, and sisymbrium philippianum.

 

 

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LOCAL RESOURCES

The workforce consists of 835 employees. In addition, there are approximately 1,150 contractors. Camp facilities are provided on site for both company personnel and contractor personnel. Personnel generally work on a four day rotation and are transported to and from site by company bus or light vehicles.

INFRASTRUCTURE

WATER

Process water is supplied from groundwater at Negrillar, 130 km east of Zaldívar. The water is drawn from six production wells and pumped to the freshwater pond near the tertiary crushing facility at the plant site. Current use is approximately 220 L/s.

POWER

Zaldívar consumes a nominal 72 MWh to 76 MWh. The power supplier is AES Gener. The power transmission is part of Sistema Interconectado del Norte Grande (SING), the regional electrical grid for Northern Chile. A dual-circuit, 220 kV, 230 km long transmission line was constructed with MEL between the Zaldívar and Escondida Norte plant sites and the SING substation at El Crucero.

PHYSIOGRAPHY

Rugged mountains with incised steep-sided valleys characterize the Zaldívar Project area. Elevations in the region vary from approximately 1,500 m to 3,500 m, and the alpine climate is cold, dry, and windy. Vegetation is sparse. Rock outcrops and colluvial soils predominate in the valley walls with colluvium, alluvium, and moraine till exposed on the valley floors. The overburden is approximately 20 m to 50 m thick in the northern part of the property and up to 100 m thick to the south.

 

 

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6 HISTORY

EXPLORATION AND OWNERSHIP HISTORY

The exploration and ownership history is summarized below:

 

1979 The initial declaration or statement of discovery (manifestación minera) was presented to the First Civil Court of Antofagasta by Mr. Pedro Buttazzoni Alvarez.

 

1981 Mr. Buttazzoni, through his company Sociedad Contractual Minera Varillas (SCMV), formed the company Sociedad Legal Minera Zaldívar 262 de Zaldívar. Shareholders in this new company were SCMV (88.33%) and Minera Utah de Chile Inc. and Getty Mining (Chile) Inc. (with a joint interest of 11.67%).

1981-1984     Exploration drilling was done in the area by Minera Utah de Chile Inc.

 

1989 As a result of various transactions during the previous eight years, SCMV held 51% and MEL the remaining 49%. In March 1989, the mining rights were sold to Sociedad Minera La Cascada Limitada (SMCL-Pudahuel). A sales contract was executed between SMCL-Pudahuel and Outokumpu Resources (Services) Limited. The mining claims were then transferred to Minera Outokumpu Chile Limitada (Outokumpu) in November.

 

1992 Outokumpu announced the formation of a 50/50 joint venture with Placer in December, at which time a joint venture company, CMZ, was formed.

 

1995 Commercial production started in November. The capital cost of the project was within budget at approximately $600 million.

 

1999 Placer acquired Outokumpu’s 50% interest in CMZ, effective December 13, 1999.

 

2006 Barrick acquired Placer on March 3, 2006.

PRODUCTION HISTORY

Since commencement of commercial operations in 1995, the following significant changes have been made:

 

1996 The feed system to the secondary crushers was improved in September 1996 by the addition of a feed bin with belt feeders controlling the material flow to each crusher.

 

1997 A pre-screening plant was installed in July 1997 to allow -12 mm material (approximately 40% of the heap leach ore) to bypass tertiary crushing. In January 1998 these screens were converted from the original wet design to dry operation.

 

 

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The installation has not only alleviated problems in the tertiary crusher, but has also proven advantageous to leach performance by bypassing fine material directly to the heap leach pad.

 

1998 In January 1998 a flotation plant was put into operation to recover copper from the tertiary crusher circuit slimes.

 

1998 In May 1998, two-pass leaching was introduced by installing an intermediate PLS pond in the heap leach circuit. This has improved leach recovery by substantially increasing the wash rate and the PLS grade.

 

1999 In April 1999 the heap leach operation was converted to an on/off (dynamic) pad.

 

2000 In July 2000, a fifth tertiary crusher line was installed, enabling part of the wet flush crusher circulating load to be treated in open circuit by two MP500 crushers.

 

2001 In March 2001, the first PLS from dump leaching was introduced to the SX circuit.

The open pit fleet has been progressively upgraded and expanded as plant feed requirements have increased. The current open pit fleet has the capacity to move approximately 240,000 tpd of material.

The electrowinning plant has been modified to produce 150,000 tonnes (330.7 Mlb) of copper cathode per year, 20% over the original design capacity of 125,000 tonnes.

Table 6-1 shows the production from the Zaldívar Mine since 2007.

 

 

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TABLE 6-1 ZALDÍVAR PRODUCTION – 2007-2011

Barrick Gold Corporation – Zaldívar Mine

 

Item

   2007      2008      2009      2010      2011
(Jan-Oct)
 

Mine to Heap Leach (t)

     16,144,945         15,141,101         15,708,166         14,506,756         12,782,070   

TCu (%)

     0.822         0.778         0.722         0.697         0.646   

ASCu (%)

     0.602         0.576         0.456         0.427         0.402   

Mine to Stockpile (t)

     7,839,300         9,940,350         16,542,135         13,087,447         4,852,549   

TCu (%)

     0.563         0.538         0.520         0.534         0.634   

ASCu (%)

     0.325         0.335         0.256         0.260         0.354   

Mine to Dump Leach (t)

     14,037,870         19,253,647         21,772,868         8,413,425         9,718,600   

TCu (%)

     0.348         0.364         0.404         0.386         0.349   

ASCu (%)

     0.177         0.183         0.165         0.173         0.176   

Waste (t)

     32,553,025         29,953,500         13,183,650         21,604,314         26150141   

Total Mine (t)

     70,575,140         74,288,598         67,206,819         57,611,942         53,503,360   

Stockpile to Heap Leach (t)

     3,169,034         4,027,521         5,436,157         6,560,624         4,736,268   

TCu (%)

     0.782         0.827         0.724         0.740         0.595   

ASCu (%)

     0.536         0.511         0.466         0.469         0.364   

Stockpile to Dump Leach (t)

     —           —           —           11,116,781         8,299,575   

TCu (%)

     —           —           —           0.510         0.392   

ASCu (%)

     —           —           —           0.459         0.190   

Total Stockpile (t)

     3,169,034         4,027,521         5,436,157         17,677,405         13,035,843   

Total Mine and Stockpile (t)

     73,744,174         78,316,119         72,642,976         75,289,347         66,539,203   

Total to Heap Leach (t)

     19,313,979         19,168,622         21,144,323         21,067,380         17,518,337   

TCu (%)

     0.816         0.789         0.723         0.710         0.632   

ASCu (%)

     0.591         0.562         0.458         0.440         0.391   

Total to Dump Leach (t)

     14,037,870         19,253,647         21,772,868         19,530,206         18,018,175   

TCu (%)

     0.348         0.364         0.404         0.456         0.369   

ASCu (%)

     0.177         0.183         0.165         0.336         0.183   

 

 

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7 GEOLOGICAL SETTING AND MINERALIZATION

REGIONAL GEOLOGY

The Zaldívar porphyry copper deposit is situated on the western margin of the Atacama Plateau in northern Chile. The deposit is part of a large Tertiary porphyry copper system that includes the Escondida porphyry copper deposit. This porphyry complex occurs within the West Fissure structural system, a major regional feature that has controlled the emplacement of some of the largest porphyry copper deposits in northern Chile (Figure 7-1). The West Fissure system extends for approximately 1,000 km and separates Paleozoic rocks to the east from Mesozoic and Paleocene rocks to the west. The Zaldívar porphyry system lies at the intersection of the West Fissure and a series of northwest and northeast striking faults.

Supracrustal rocks in the region range in age from Paleozoic to the Quaternary. Rhyolitic and andesitic flow units of the Upper Paleozoic La Tabla Formation and the Upper Triassic Agua Dulce Formation are exposed in the east. The southwestern portion of the area is overlain by marine sedimentary rocks assigned to the Upper Triassic–Lower Jurassic Profeta Formation and Cretaceous continental units of the Santa Ana Formation. Andesite volcanic and volcaniclastic units occupy the north and central parts of the area. These belong to the Upper Cretaceous–Eocene age Augusta Victoria Formation. Two periods of intrusive activity occurred in the region. Dioritic and monzonitic intrusives were emplaced during the Upper Cretaceous–Eocene age, and dioritic to rhyolitic porphyries occurred during Eocene–Oligocene times. Oligocene–Miocene age unconsolidated gravels, alluvium, and colluvium cover the older rock units.

 

 

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LOCAL AND PROPERTY GEOLOGY

The Zaldívar porphyry is located at the intersection of the north-south striking faults of the Domeyko Fault system with the northeast and northwest striking faults. The deposit is generally centred on a northeast striking granodiorite porphyry body that intrudes andesites and rhyolites, and cuts across the north-south striking Portezuelo Fault.

There are three main lithologic units at Zaldívar: the Zaldívar porphyry, the andesite unit, and the Llamo porphyry (Figure 7-2). At approximately 290 million years old (Richards et al., 1999), the Zaldívar porphyry is the oldest unit and occupies most of the area east of the Portezuelo Fault. This rock unit typically consists of grey rhyolitic feldspar-quartz porphyry. Phenocrysts are mainly quartz, K-feldspar, and plagioclase. The quartzo-feldspathic groundmass is variably obliterated by sericite due to prevalent phyllic (quartz–sericite) alteration.

The andesite unit correlates with the August Victoria Formation, which has been dated between 66.6 and 41.2 million years (Marinovic et al., 1995) and it is the dominant lithology west of the Portezuelo Fault. Rocks are greenish grey to dark grey and display a fine-grained porphyritic texture with an aphanitic groundmass. The Llamo porphyry is the most recent intrusive event in the area and is dated at approximately 37.4 million years old (Richards et al., 1999). The porphyry trends roughly northeast-southwest across the deposit, outcropping on either side of the Portezuelo Fault where it intrudes both the andesite unit and the Zaldívar porphyry. It occurs as irregularly shaped dikes to small stock-like bodies 50 m to 200 m wide. This rock unit, a feldspar-biotite-quartz porphyry, is typically light greyish green and fine grained.

Several hydrothermal and tectonic breccias bodies closely associated with major structures, such as the Portezuelo Fault, have been recognized in the mine area. Much of the lower slopes and valley floors in the area are covered with thick Quaternary alluvial/colluvial deposits. These deposits are locally derived and generally consist of dry, loose to dense, well-graded silt, sand, and gravel. Pockets of aeolian silt and fine sand also occur in the area.

 

 

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The Zaldívar deposit occurs at the intersection of three major sets of faults striking north-south, northwest-southeast, and northeast-southwest. This structural setting has controlled the emplacement of the intrusives and hypogene mineralization as well as leaching and secondary enrichment.

The most prominent structures strike north-south and northwest-southeast and dip moderately to steeply northeast to southwest. Breccia zones one metre to five metres wide are commonly associated with the north-south fault set. These faults mimic the regional structures. The north-south set parallels the West Fissure structural trend, which is approximately 10 km wide and consists of an arrangement of steeply dipping, north-south trending structures. The northwest-southeast set parallels a regionally continuous, secondary structural trend. Both fault sets appear to be pre-intrusive and presumably control the emplacement of subsequent intrusions. It is also at the intersection of these faults that copper mineralization is best developed. A second set of faults strike northeast-southwest with steep dips to the northwest and southeast. This set is weakly to moderately developed, however, it is closely associated with the Zaldívar deposit and may have controlled the emplacement of the Llamo porphyry.

ALTERATION

The alteration developed in the Zaldívar Porphyry correspond to an early potassic alteration event, represented by secondary K-feldspar, which affect the Llamo Porphyry and the Paleozoic rocks below the 3,050 m elevation, and by secondary biotite, which widely affects the andesitic rocks.

This alteration is overprinted by low temperature quartz-sericite hydrothermal alteration with two stages of development. An early wide spread stage of sericite-chlorite alteration followed by the principal stage with more penetrative quartz-sericite-pyrite alteration focused in the mid part of the deposit and with a clear association with the Llamo Porphyry intrusions. Strong sericite alteration is present as discontinuous bodies in the core of the quartz-sericitic alteration zones and typically destroys primary rock textures. Propylitic alteration with chlorite as the main mineral effects the andesitic rocks and the late Llamo Porphyry.

 

 

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The final stage of the system is represented by very restricted advanced argillic alteration. Finally, as result of the leaching and oxidation of the rock column of the deposit, the supergene argillic alteration is developed, affecting all the lithological types with variable intensity, but being typically stronger in the andesitic rocks.

MINERALIZATION

The mineralization has an elongated shape trending northeast-southwest. This is the result of the overprinted hypogene and supergene processes, where the latter with its leaching and enrichment process, gave the deposit a characteristic vertical profile with a superior leached zone, an oxide copper zone, and a secondary sulfide zone located between the oxide and the basal primary sulfide zone.

The leached zone is present as a continuous horizon in the upper part of the deposit, with local depths of up to 300 m. The typical mineralogy of this zone includes hydroxides and iron sulfates (hematite-goethite-jarosite) with copper phosphate (turquoise).

The oxide zone extends more or less continuously from the Portezuelo Fault and surrounding areas towards the southwest, covering an area of approximately 2 km by 1.5 km and with an average thickness of approximately 90 m. The oxide zone is incised locally by leached areas related to faults of the northwest-southeast structural system. The mineralogy varies according to lithology and dominant alteration. For example, brochantite-antlerite is found in the rhyolitic rocks and chrysocolla, “black copper”, and copper phosphate are found in the andesitic rocks with chlorite-biotite alteration.

The secondary sulfides cover an area of approximately 2.5 km by 1.5 km, with a variable thickness from a few metres in the southwest extremity up to over 300 m in the northeast extremity. Mineralogy in this area is represented by pyrite, chalcocite, covellite, chalcopyrite and minor sphalerite and molybdenite. Chalcocite is the dominant secondary sulfide mineral (over 80%). Covellite is the main sulfide mineral present in the transition zone to the underlying primary sulfides. Alunite dating indicates an age for the secondary enrichment process of approximately 18 My to 14.7 My (Monroy 2010).

 

 

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The primary sulphide zone follows the Llamo Porphyry trends and over 70% of the mineralization occurs in veinlets. The primary sulfide body has a bornite-rich core with minor chalcopyrite that is located in the Llamo Porphyry and in the late magmatic breccias. The bornite-rich core is enveloped by a chalcopyrite-pyrite zone which in turn is surrounded by a pyritic halo. The primary mineralization age is 37.2 My (Morales 2010).

 

 

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8 DEPOSIT TYPES

Zaldívar is a porphyry copper deposit and together with the nearby Escondida and Chimbarazo deposits form part of the Eocene-Oligocene porphyry belt of Northern Chile. They are located at the intersections of the north-south regional faults belonging to the Domeyko Fault System with northwest and northeast fault systems.

The hypogene mineralogy of the deposit begins in the late magmatic stage where early veinlets of biotite and/or magnetite with bornite or minor chalcopyrite were developed. These are followed by “A” veinlets comprising quartz, K-feldspar, anhydrite, bornite, chalcopyrite, and primary chalcocite veinlets. These veinlets occur in strong potassic alteration characterized by biotite and secondary K-feldspar. In the transition from the late magmatic stage to early hydrothermal stage, a third generation of “B” veinlets is developed with quartz and minor K-feldspar and abundant chalcopyrite and/or molybdenite. For the principal hydrothermal event of quartz-sericite alteration two stages are recognized. The “C” veinlets, characterized by quartz with chalcopyrite, molybdenite, or chalcopyrite-pyrite with sericite-chlorite haloes, develop during the early stage. The main stage is represented by “D” veinlets with or without quartz, abundant pyrite, minor chalcopyrite and sphalerite and with quartz- sericite-pyrite alteration haloes.

Later, during the Miocene, the supergene processes associated with the uplift, erosion, oxidation and leaching of the deposit in a desert environment resulted in the leached horizon, immediately underlain by the oxide copper horizon, which is underlain by the secondary sulfide horizon, which all sits on top of the primary sulfide zone.

 

 

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9 EXPLORATION

Zaldívar is a mature operation with a relatively small mining concession area. The major exploration programs took place prior to the completion of the feasibility study in 1993. A major drilling campaign was completed in 2000 to define the limits of the deposit within the mining concessions. More recently, deep drilling campaigns have targeted the underlying sulphide mineralization. CMZ drills approximately 15,000 m of infill reverse circulation drill holes each year.

EXPLORATION POTENTIAL

CMZ has been evaluating the economic potential of the primary copper mineralization for a number of years. RPA first reviewed the Zaldívar Deeps Sulphide Cu-Mo-Au-Ag Project in January 2009 (Scott Wilson RPA, 2009) after Barrick completed an internal scoping study in December 2008 (Croal and Tsafaras, 2008). A new scoping study by Barrick is almost complete.

CMZ built a new block model for this primary sulphide mineralization as part of the 2010 mid-year update. There appears to be sufficient drill holes and technical studies completed to demonstrate that the Zaldívar Deep Sulphide Cu-Mo-Au-Ag Project mineralization meets the requirement for “reasonable prospects for economic extraction”.

 

 

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10 DRILLING

The resource model is based on 1,735 drill holes totalling 460,199 m that were drilled up to April 12, 2011 (Table 10-1). Approximately 60% of the drilling was by reverse circulation (RC) and the balance was diamond drill holes (DDH). Some 57 DDHs totalling 11,470 m were drilled from an underground bulk sample drift, which is now partly visible in the east wall.

Essentially all of the samples have total copper (TCu) grades, approximately 85% of the samples have acid soluble copper (ASCu) grades, and 43% of the samples have cyanide soluble copper (CNCu) grades. Approximately 21% of the samples have molybdenum (Mo), gold (Au), and silver (Ag) grades and these are mostly present in the primary sulphide mineralization.

Most of the resource definition drilling was completed in 1999 and 2000. Most holes were drilled vertically. When inclined, the drilled orientations were generally north-south, east-west, northeast-southwest, or northwest-southeast. Dip angles ranged from -40° to -90°, except for the east-west oriented holes where dip angles ranged from 0° to -90°.

The drill holes were mostly spaced approximately 100 m apart for the feasibility study and are now mostly spaced approximately 50 m apart. The mine plans to drill approximately 15,000 m annually to ensure that three years of production are always supported by approximately 50 m spaced holes.

All drill collars were surveyed by mine survey staff and located relative to the mine grid. Drill holes were downhole surveyed using mostly a Sperry Sun instrument at an average interval of 30 m and more recently gyroscopic downhole surveys have been done by Wellfield Services Ltda. (WS) and Perfochile Ltda. personnel. WS has also scanned holes for detailed structural analyses using a process called “Televisor Acustico de Pozos” and this procedure also generates a second set of downhole survey readings that can be used to confirm the accuracy of the gyroscopic data.

 

 

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TABLE 10-1 DRILLING SUMMARY

Barrick Gold Corporation – Zaldívar Mine

 

          No.      RC      DDH      Total  

Description

   Year    Holes      (m)      (m)      (m)  

1. Exploration Holes

              

Utah

   1981-1989      60         10,986.0         9,090.0         20,076.0   

Cascada

   1989      41         15,873.0            15,873.0   

Outokumpu

   1990-1992      308         32,814.0         42,479.0         75,293.0   

Outokumpu /Placer Dome

   1992      12         952.0         1,805.0         2,757.000   

Placer Dome

   1992-1993      80         8,910.0         5,736.0         14,646.0   

Total Exploration Holes

        501         69,535.0         59,110.0         128,645.0   

2. Condemnation Holes

              

Zaldívar/Escondida

   1993-1993      35         4,624.0            4,624.0   

Zaldívar

   1995      5         1,556.0            1,556.0   

Total Condemnation Holes

        40         6,180.0            6,180   

3.-CMZ Holes (Secondary Exploration/Production)

              

Minera Zaldívar

   1994-1998      243         37,777.0         4,463.0         42,240.0   

Geotechnical Drilling

   1998      9            2,224.7         2,224.7   

Zaldívar Total Life Drilling

   1999      151         21,690.0         6,485.7         28,175.7   

Zaldívar Total Life Drilling

   2000      247         41,558.0         20,045.0         61,603.0   

Infill Drilling

   2001      31         2,942.0            2,942.0   

Infill Drilling

   2003      22         2,600.0            2,600.0   

Geotechnical Drilling

   2003      9            1,920.0         1,920.0   

Infill Drilling

   2005      24         4,613.0            4,613.0   

Infill Drilling

   2006      24         5,756.0            5,756.0   

Geotechnical Drilling

   2006      15            4,595.7         4,595.7   

Primary Drilling

   2006      15         3,684.0            3,684.0   

Primary Drilling

   2006      3            1,401.7         1,401.7   

Infill Drilling

   2007      67         15,151.0            15,151.0   

Primary Drilling

   2007      2         600.0            600.0   

Primary Drilling

   2007      59            42,995.7         42,995.7   

Geotechnical Drilling

   2007      10            2,658.2         2,658.2   

Geotechnical Drilling

   2008      24            14,936.9         14,936.9   

Hydrogeological

   2008      6            3,615.0         3,615.0   

Hydrogeological

   2008      2         440.0            440.0   

Infill Drilling

   2008      70         17,172.0            17,172.0   

Primary Drilling

   2008      41            22,621.4         22,621.4   

Primary Drilling (Metallurgical)

   2008      2            612.9         612.9   

Hydrogeological

   2009      15         3,213.0            3,213.0   

Infill Drilling

   2009      37         11,000.0            11,000.0   

Infill Drilling

   2010      75         22,258.0            22,258.0   

Hydrogeological

   2010      13         2,954.0            2,954.0   

Infill Drilling

   2010      54         12,184.0            12,184.0   

Infill Drilling

   2011      13         3,530.0            3,530.0   

Total

        1,283         209,122.0         128,575.7         337,697.7   
     

 

 

    

 

 

    

 

 

    

 

 

 

Grand Total (December 2011)

        1,824         284,837.0         187,685.7         472,522.7   

 

 

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The holes have been logged properly and more recently (2007/2008) the mine has started logging directly into hand-held computers using PC Explorer software for the RC holes and GVMapper for the DDHs. The data captured includes lithology, type and degree of alteration, style and mineralogy of oxide and sulphide mineralization, structural observations, and style and frequency of fractures and veins. The blasthole chips are also logged.

A significant amount of core was relogged to update and standardize the lithology, alteration, and mineralization codes in the earlier drill holes. It is RPA’s opinion that the CMZ drilling and logging procedures are of high quality and they exceed standard industry practices. The drill hole locations are shown in Figure 10-1.

 

 

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11 SAMPLE PREPARATION, ANALYSES AND SECURITY

SAMPLING METHOD AND APPROACH

Core is sampled on one and two metre intervals and RC material is sampled on two metre intervals. Core samples are split, with half being submitted for analyses and the remaining half preserved and stored at a secure facility on site. Holes are commonly sampled in their entirety. The samples are tagged and transported by the geological staff to the respective assay laboratory.

The blasthole samples are taken with a 10 cm diameter by 0.7 m long tube from six locations from the piles around each hole. The blasthole samples are approximately 20 kg to 25 kg. The drills have skirts to help prevent loss of fines during strong winds.

RPA is of the opinion that the core, RC, and blasthole sampling procedures at Zaldívar are reasonable.

SAMPLE PREPARATION, ANALYSES AND SECURITY

In the early phases of drilling (prior to pre-production), outside assay laboratories such as Geoanalitica Ltda. (Geoanalitica), CIMM, and CESMEC were routinely used. Since the commissioning of the mine site assay laboratory in 1994, all drill samples have been prepared on site. CMZ has a large, well-organized, clean, ISO 17025 certified mine laboratory.

In 1996 and 2000, Francis Pitard developed sampling and preparation procedures for RC and blasthole samples. At least 20 kg of material is dried, crushed to 100% passing 10 mesh, passed through a rotary splitter, and approximately 250 g is pulverized to 90% passing 170 mesh. All samples are weighed and the weights are monitored by the geology department. Regular sieve tests are carried out and the CMZ mine lab pulps regularly achieve better than 95% passing 170 mesh.

CMZ has provided Geoanalitica with the CMZ analytical protocols for sequential copper analyses. The samples are analyzed for total copper (TCu), acid soluble copper (ASCu), and cyanide soluble copper (CNCu) at the Geoanalitica laboratory in Coquimbo, Chile. The detection limit is 0.01% for TCu, ASCu, and CNCu.

 

 

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The drill core, field duplicates, and reject material is stored for one year at a very well organized and secure location on site. The 250 g pulps are placed in small plastic screw-top containers and stored forever in 45 gal drums.

RPA is of the opinion that the sample preparation, analytical protocols, and security measures are very good and exceed industry standard practice.

QUALITY ASSURANCE AND QUALITY CONTROL

CMZ has very good quality control (QC) and quality assurance (QA) procedures that include the regular insertion of in-house standards, blanks, field duplicates, reject duplicates, and pulp replicates. In addition, pulps are sent to external laboratories on a regular basis.

Geoanalitica is the primary laboratory for the DDH and RC samples and the CMZ laboratory is the primary laboratory for the blasthole samples. The CMZ laboratory is the secondary laboratory for the external DDH and RC pulp replicates and Geoanalitica is the secondary laboratory for the external blasthole pulp replicates. In March 2007, CMZ implemented the Barrick QA/QC procedures and they are well documented in Morales (2009).

The approximate insertion rates for blasthole, RC, and DDH samples are essentially the same and are summarized in Table 11-1.

TABLE 11-1 QC INSERTION RATES

Barrick Gold Corporation – Zaldívar Mine

 

Description

   Approximate Insertion Rate

Standards

   5%

Blanks

   2%

Pulp Replicates

   2%

Reject duplicates

   2%

Field Duplicates

   2%

Sieve Tests

   5%

External pulp replicates (more blanks and standards sent as well)

   5%

 

 

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The actual insertion rates vary slightly by year and sample type. For example, the 2010 exploration drilling program insertion rates for standards (8%), blanks (4%), and external checks (6%) exceeded those in Table 11-1.

Barrick personnel use a number of control charts and graphs to closely monitor the QA/QC results and re-analyses are periodically requested. The insertion rates and results are well-documented and reveal no significant biases or precision problems.

RPA is of the opinion that the QA/QC procedures are very good and exceed standard industry practice. Reduction in the QC insertion rates, particularly for the blasthole samples, might be warranted.

 

 

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12 DATA VERIFICATION

The blasthole and exploration drill hole data have been stored in acQuire™ databases since 2000 and 2005, respectively. Most interaction with the database is through the acQuire™ front-end “Geoscientific Information Management System” (GIMS), which facilitates data entry and export, validation, QA/QC, and reporting. A geological database administrator based at the mine site is responsible for maintaining the data integrity and structure and ensuring back-ups and stored procedures are run correctly.

The Zaldívar exploration database is regularly validated by mine staff using validation routines in acQuire™ and other mining software. Mine personnel also visually check the drill hole data on-screen on a regular basis. Zaldívar has a well-established routine of extensively checking and validating data through all stages of data collection and data import.

CMZ has formal signed data verification reports supporting data verification work completed on exploration drill hole data generated from 2007 to 2011 (Solis, 2011, Monroy, 2008 to 2010, Perez, 2008, and Morales, 2008). In general, approximately 10% of the assays, 100% of the collar coordinates, and 10% of the downhole survey data are checked annually and prior to each resource model update.

The amount of actual historical database verification work that was completed prior to 2007 is not well documented. In 2004 and 2006, PDI carried out Level 2 audits and identified no problems with the exploration drill hole database (Placer 2004 and 2006). In 2004, AMEC reviewed the data verification process and results and concluded that the assay and survey data was sufficiently free of error to be adequate for resource estimation (AMEC, 2004).

The ultimate validation of the reliability of the exploration drill hole database is provided by the very good reconciliation between the resource model and production.

RPA used a number of data validation queries in Access and Vulcan and did some visual checks and found essentially no database validation problems, which is remarkable considering the database size. RPA is of the opinion that the drill hole database is valid and acceptable for resource estimation.

 

 

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13 MINERAL PROCESSING AND METALLURGICAL TESTING

METALLURGICAL TESTING

Actual process copper recoveries are determined based on head grade samples to the crushed ore leaching process against tailings grade values for the spent ore determined from drill sampling of the ore prior to rehandling to the dump and reconciled with copper recovered to leach solutions and ultimately to cathode production. Leach solutions and volumes are sampled on a continuous basis from the various sources of pregnant solution (dynamic pad, ROM pad, and permanent secondary leach pad).

Metallurgical testing by CMZ and the University of Utah has demonstrated that the highest grade minerals have lower recoveries. With total copper above 1.3%, copper recovery drops by approximately 8% to 16%. This is due to the higher grade ores having a larger percentage of encapsulated copper. Recovery is discussed further in Section 17.

 

 

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14 MINERAL RESOURCE ESTIMATE

SUMMARY

Table 14-1 summarizes open pit Mineral Resources exclusive of Mineral Reserves as of December 31, 2011, based on a $3.25/lb copper price. The 2011 year-end Measured and Indicated Mineral Resources total 124.8 million tonnes averaging 0.445% TCu and contain 1.22 billion pounds of copper. In addition, the 2011 year-end Inferred Mineral Resources total 37 million tonnes averaging 0.54% TCu and contain 0.44 billion pounds of copper. The resource model was prepared by Barrick Senior Resource Geologist Cristian Monroy under the supervision of Barrick Superintendent of Resource and Reserve Modelling Benjamin Sanfurgo.

TABLE 14-1 MINERAL RESOURCES – DECEMBER 31, 2011

Barrick Gold Corporation – Zaldívar Mine

 

Category

   Tonnage
(Mt)
     Grade
(% Cu)
     Contained Metal
(Mlb Cu)
 

Measured

     71.3         0.432         679.5   

Indicated

     53.5         0.462         545.5   
  

 

 

    

 

 

    

 

 

 

Total Measured and Indicated

     124.8         0.445         1,225.0   

Inferred

     37         0.54         439   

Notes:

1. CIM definitions were followed for Mineral Resources.
2. Mineral Resources are estimated based on a profit model using a copper price of US$3.25 per pound and a CLP/USD exchange rate of 500.
3. Mineral Resources are exclusive of Mineral Reserves.
4. Numbers may not add due to rounding.

RPA reviewed the resource assumptions, input parameters, geological interpretation, and block modelling procedures and is of the opinion that the Mineral Resource estimate is appropriate for the style of mineralization and that the resource model is reasonable and acceptable to support the 2011 year end Mineral Resource and Mineral Reserve (MRMR) estimates.

RPA is not aware of any environmental, permitting, legal, title, taxation, socio-economic, marketing, political, or other issues that could materially affect the MRMR estimates.

 

 

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GEOLOGICAL MODELS

The CMZ geology department has developed a very good understanding of the Zaldívar geology. Geological models were constructed to provide geologic control for grade estimation and to provide parameters for mine planning. Geology models for lithology, alteration, and mineralization were built using Leapfrog™ software. The main faults have also been modelled. Interpretations were made by mine geology personnel on 25 m and 50 m cross sections looking 045°. Lines and control points based on the exploration drill holes, blastholes, and pit mapping were used in Leapfrog to create 3D geological wireframes. The geological wireframes were reviewed by mine personnel and minor revisions were made locally.

Wireframes were built for the main lithology, alteration, and mineralization zones listed below and they were used to assign codes to the block model.

Lithology Codes

1 = Andesite (AND)

2 = Hydrothermal Breccia (BXX)

3 = Late Llamo Porphyry (LPT)

4 = Llamo Porphyry (LPY)

5 = Zaldívar Porphyry (ZPY)

6 = Magmatic Breccia (BXP)

7 = Granite (GGB)

8 = Gravel (SCG)

9 = Deep Andesite (ANDP)

Alteration Codes

1 = Argillic (ARG)

2 = Biotitic (BIO)

3 = Chloritic (CLO)

4 = Potassic (POT)

5 = Quartz-Sericite (QSE)

6 = Sericitic (SER)

7 = Silicic (SIL)

8 = Gravel (SCG)

Mineralization Codes

1 = Oxide (OX)

2 = Leached (LIX)

3 = Secondary Sulphide (SEE)

4 = Secondary-Primary Mixed Sulphide (MSP)

5 = Primary Sulphide (PRI)

8 = Gravel (SGG)

 

 

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The lithology, alteration, and mineralization models are shown in Figures 14-1 to 14-3, respectively.

The mineralization interpretation is based on a number of ASCu/TCu and (ASCu+CNCu)/TCu thresholds such as:

 

Leached:

   TCu <0.25% and ASCu/TCu > 0.35

Oxide:

   TCu >0.25% and ASCu/TCu > 0.35

Sulphide:

   ASCu/TCu < 0.35

Secondary Sulphide:

   (ASCu+CNCu)/TCu > 0.5

Mixed Sulphide:

   (ASCu+CNCu)/TCu > 0.5 and <0.35

Primary Sulphide:

   (ASCu+CNCu)/TCu <0.35

 

 

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GEOLOGICAL DOMAINS

CMZ has defined 13 geological estimation domains (UGE). The alteration has been grouped into the more intense central alteration (QSE+POT) and weaker peripheral alteration (Arg-Bio-Clo-Si).

UGE1 and UGE2 represent barren gravel and barren post-mineralization late Llamo porphyry intrusions, respectively. UGE3 and UGE4 are the oxide mineralization split up by alteration intensity. Leached Domains UGE5 and UGE6 are subeconomic domains that were interpolated separately because the leached zone around the Zaldívar porphyry to the east averages only 0.06% TCu compared to the rocks to the west, which average 0.15% TCu. UGE7 to UGE9 are related to the secondary sulphide mineralization. UGE10 represents the mixed sulphide mineralization and UGE11 to UGE13 are used for the primary sulphide model. UGE2, UGE12, and UGE13 are volumetrically insignificant.

The estimation domains are summarized in Table 14-2. RPA has reviewed the geological reasoning and descriptive statistics for each UGE and is of the opinion that these geological domains are reasonable and acceptable.

TABLE 14-2 GEOLOGICAL ESTIMATION UGE CODES AND

DESCRIPTIONS

Barrick Gold Corporation – Zaldívar Mine

 

UGE

  

Type

  

Description

1    Gravel    SCG
2    Late Llamo Porphyry    LPT
3    Oxide    (BIO + POT + SER)(AND-BXX-LPY ) + AND(ARG) + BXP
4    Oxide    (QSE + SIL + CLO)(AND-BXX-LPY-ZPY) + ARG(BXX-LPY-ZPY)
5    Leached    AND + LPY + BXX + BXP
6    Leached    ZPY
7    Secondary Sulphide    (QSE + ARG)(BXX-LPY-ZPY) + SIL(BXX-LPY) + LPY(CLO-POT) + BXX(BIO-CLO-POT)
8    Secondary Sulphide    AND(QSE-SIL-CLO) + BXX(SER) + ZPY(CLO-POT-SIL)
9    Secondary Sulphide    BIO(AND-LPY-ZPY-BXP) + POT(AND-ZPY-BXP) + (ARG-SER)
10    Mixed Sulphide    MSP
11    Primary Sulphide    AND + ZPY + LPY + GGB + BXX
12    Primary Sulphide    BXP
13    Primary Sulphide    ANDP

 

 

Barrick Gold Corporation – Zaldívar Mine, Project #1683    Rev. 0 Page 14-7
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DENSITY DATA

CMZ has compiled the density data by the main lithological units (Table 14-3). Most of the density tests are done on core samples using a paraffin immersion density approach. The results for over 2,000 density tests are available. CMZ has also estimated a separate set of tonnage factors for the primary sulphide rock types. RPA is of the opinion that the tonnage factors are reasonable and acceptable.

TABLE 14-3 TONNAGE FACTORS

Barrick Gold Corporation – Zaldívar Mine

 

Rock Type

   Main  Model
(t/m³)
 

Gravel Overburden (SCG)

     2.101   

Argillite (ARG)

     2.451   

Andesite (AND)

     2.562   

Breccias (BXX)

     2.520   

Llamo Porphyry (LPY)

     2.490   

Zaldívar Porphyry (ZPY)

     2.523   

CUT-OFF GRADES

Due to the complex processing strategy in use at Zaldívar where operating costs vary by process stream as well as ore types, multiple cut-off grade values are used. Separate resource and reserve cut-off grades, based on the resource and reserve copper prices, are used to report the resources and reserves. The cut-off grade is based on process cost, ore type, and recovery. All blocks that fail to meet the cut-off grade are classified as waste.

CAPPING OF HIGH GRADE VALUES

CMZ capped high TCu, ASCu, and CNCu assays prior to compositing based on examining log probability plots of the assays for the main types of mineralization, and inside the primary sulphide for each type of lithology. In general, the TCu assays are relatively insensitive to capping and the ASCu assays are moderately sensitive to capping. The decrease in metal due to capping is generally less than a few percent (Tables 14-4 and 14-5).

 

 

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TABLE 14-4 TCU CAPPING LEVELS

Barrick Gold Corporation – Zaldívar Mine

 

Min Zone Raw Data Cut >0.01%

    Total Copper Grade (%)      Total Coper Capp  

Description

   Meters      % Meters     Mean      Std.dev      Min      1Q      Median      3Q      Max      CV      Capping      CV capped      GT lost     Percet  

All zones

     429320           0.417         0.799         0.002         0.100         0.230         0.430         45.800         1.92         15.00         1.83         0.3     100.0

CUO

     95301         22.2     0.655         0.994         0.003         0.250         0.400         0.701         45.800         1.52         12.00         1.41         0.6     99.9

LXX

     100483         23.4     0.157         0.272         0.004         0.030         0.100         0.210         15.800         1.73         1.50         1.17         3.5     99.7

SSE

     72211         16.8     0.887         1.317         0.005         0.260         0.500         1.040         42.200         1.48         15.00         1.39         0.6     99.9

MSP

     19925         4.6     0.362         0.337         0.010         0.190         0.280         0.427         10.250         0.93         2.00         0.79         1.6     99.5

PRI

     114046         26.6     0.242         0.258         0.002         0.110         0.200         0.310         27.700         1.07         1.50         0.79         1.3     99.8

GRAV

     22691         5.3     0.069         0.140         0.002         0.020         0.030         0.060         5.378         2.02         0.80         1.53         3.8     99.6

LPT

     684         0.2     0.120         0.229         0.005         0.010         0.020         0.080         1.850         1.91         0.50         1.40         12.0     95.3

From Monroy, 2011

TABLE 14-5 ASCU CAPPING LEVELS

Barrick Gold Corporation – Zaldívar Mine

 

Min Zone Raw Data CuS >0.001%

    Soluble Copper Grade (%)      Soluble Copper Capp  

Description

   Meters      % Meters     Mean      Std.dev      Min      1Q      Median      3Q      Max      CV      Cappinq      CV capped      GT lost     Percet  

Allzones

     367381           0.155         0.427         0.001         0.010         0.040         0.130         15.240         2.75         7.00         2.60         0.7     100.0

CUO

     89987         24.5     0.439         0.724         0.001         0.100         0.220         0.490         15.240         1.65         7.00         1.54         0.9     99.8

LXX

     68627         18.7     0.082         0.228         0.001         0.010         0.030         0.080         15.200         2.79         1.50         1.77         5.2     99.7

SSE

     66670         18.1     0.132         0.296         0.002         0.040         0.080         0.140         13.300         2.24         3.50         1.85         2.0     99.9

MSP

     17127         4.7     0.040         0.064         0.005         0.016         0.030         0.040         3.750         1.61         0.40         1.12         2.6     99.7

PRI

     105307         28.7     0.019         0.030         0.001         0.005         0.010         0.020         1.600         1.60         0.30         1.26         1.6 %      99.9

GRAV

     18116         4.9     0.023         0.110         0.001         0.005         0.005         0.010         5.318         4.81         0.50         2.36         15.8     99.4

LPT

     747         0.2     0.012         0.034         0.005         0.005         0.005         0.010         0.570         2.63         0.10         1.05         16.0     98.9

From Monroy, 2011

CMZ also applied restricted search radii of 30 m to 45 m to passes 2 to 4 for oxide (UGE3 and 4) and secondary sulphide (UGE7 and 8) composites with grades above 3% TCu. In addition, a restricted search with 30 m radii was applied to passes 1 to 4 for the composites with ASCu grades above 1.5% in UGE3 and 3.0% in UGE4.

RPA concurs with the capping levels and restricted search conditions selected by CMZ. The production reconciliation results confirm that they are reasonable.

COMPOSITES

Drill hole sample data were composited into five metre lengths starting at the drill hole collars. Remnant composites shorter than three metres were discarded. Figure 14-4 shows the frequency distribution of the total copper grades in the five metre composites versus the raw sample data.

 

 

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FIGURE 14-4 FREQUENCY DISTRIBUTION OF TCU COMPOSITES VERSUS

RAW SAMPLE DATA

 

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From Monroy, 2011

The composites with at least three metre lengths, which represent 99.5% of the whole sample data, were used for the estimate. A small number of composites with lengths less than three metres that were excluded are remnants located at mineralization contacts and hole bottoms.

The composite statistics for each UGE are summarized in Table 14-6 and shown as boxplots in Figure 14-5. The relative abundance of composites in each domain is also summarized in Table 14-6. For example, 22% of the composites occur in oxide mineralization (UGE3 and UGE4) and 16.7% of the composites are in secondary sulphide mineralization (UGE7 to 9).

 

 

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TABLE 14-6 TCU COMPOSITE STATISTICS BY GEOLOGICAL DOMAIN (UGE)

Barrick Gold Corporation – Zaldívar Mine

 

           Total Copper Grade (%)  

Domain

   Code      Metres      % Metres     Mean      Std Dev      Min      1Q      Median      3Q      Max      CV  

All zones

        435,414           0.412         0.662         0.003         0.110         0.244         0.442         19.350         1.61   

UGE1

     1         24,630         5.7     0.070         0.140         0.003         0.020         0.030         0.068         4.861         2.00   

UGE2

     2         907         0.2     0.093         0.158         0.005         0.010         0.024         0.092         1.034         1.70   

UGE3

     3         34,638         8.0     0.520         0.493         0.016         0.278         0.387         0.594         13.706         0.95   

UGE4

     4         60,974         14.0     0.731         0.881         0.010         0.280         0.464         0.838         12.308         1.21   

UGE5

     5         70,237         16.1     0.195         0.211         0.005         0.074         0.163         0.250         5.826         1.08   

UGE6

     6         32,530         7.5     0.067         0.176         0.005         0.016         0.028         0.054         3.728         2.60   

UGE7

     7         34,244         7.9     1.248         1.335         0.006         0.428         0.898         1.565         18.702         1.07   

UGE8

     8         29,435         6.8     0.601         0.736         0.005         0.252         0.425         0.714         19.350         1.23   

UGE9

     9         8,712         2.0     0.423         0.345         0.022         0.254         0.336         0.465         6.216         0.82   

UGE10

     10         19,950         4.6     0.362         0.268         0.016         0.210         0.298         0.426         3.372         0.74   

UGE11

     11         113,030         26.0     0.239         0.205         0.004         0.126         0.206         0.306         13.986         0.86   

UGE12

     12         992         0.2     0.529         0.485         0.082         0.256         0.424         0.622         3.712         0.92   

UGE13

     13         624         0.1     0.105         0.084         0.006         0.046         0.074         0.142         0.442         0.80   

From Monroy, 2011

FIGURE 14-5 BOXPLOT OF TCU COMPOSITES FOR EACH UGE

 

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From Monroy, 2011

 

 

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CONTACT PLOT ANALYSIS

Contact plots were generated for TCu, ASCu, and CNCu values to explore the relationship between the grade variable when moving from one geological domain (UGE) to another. The results showed that they were mostly hard boundaries.

The contact plots are constructed with Vulcan software. Vulcan searches for data with a given code (UGE) and then for data with another specified code (UGE) and groups the grades according to the distance between the two points. This allows for a graphical representation of the grade trends away from a “contact.” If average grades are reasonably similar near a boundary and then diverge as distance from the contact increases, then the particular boundary should probably not be used as a grade constraint (“soft”). If the averages are distinctly different across a boundary, then the boundary may be important in constraining the grade estimation (“hard”). Examples of contact plots are shown in Figures 14-6 and 14-7.

Hard boundaries were used for the box and first pass searches. For all UGEs except leached, weighted boundaries using 0.1 and 0.3 values in the composite length fields were used to simulate semi-hard and semi-soft contacts, respectively. These semi-hard and semi-soft boundaries were used for passes 2 to 5 and are shown in Figure 14-8. This weighted semi-soft approach was developed by Barrick to help reduce the estimated ASCu grades. The 0.1 and 0.3 values were selected after repeated comparisons with production reconciliation data. RPA concurs with this innovative approach.

 

 

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14-13


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14-14


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VARIOGRAPHY

CMZ built a number of downhole, directional, and omni-directional correlograms using the composites for each geological domain. Triple nested spherical models were developed for each domain and the results are summarized in Table 14-7.

TABLE 14-7 %TCU VARIOGRAM PARAMETERS

Barrick Gold Corporation – Zaldívar Mine

 

       Structure 1      Structure 2      Structure 3  

Estimation
id

   UGE      Var.
Nugget
     Model
Type
     Sill
Differential
     Major
Axis
     Semi-
Major
Axis
     (Minor
Axis
     Sill
Differential
     Major
Axis
     Semi-
Major
Axis
     Minor
Axis
     Sill
Differenti
al
     Major
Axis
     Semi-
Major Axis
     Minor
Axis
 

uge030

     3         0.12         SPHERICAL         0.5         35         23         30         0.3         100         80         100         0.08         485         400         240   

uge031

     3         0.12         SPHERICAL         0.5         35         23         30         0.3         100         80         100         0.08         485         400         240   

uge032

     3         0.12         SPHERICAL         0.5         35         23         30         0.3         100         80         100         0.08         485         400         240   

uge033

     3         0.12         SPHERICAL         0.5         35         23         30         0.3         100         80         100         0.08         485         400         240   

uge034

     3         0.12         SPHERICAL         0.5         35         23         30         0.3         100         80         100         0.08         485         400         240   

uge040

     4         0.22         SPHERICAL         0.31         15         10         15         0.27         55         60         90         0.2         500         400         125   

uge041

     4         0.22         SPHERICAL         0.31         15         10         15         0.27         55         60         90         0.2         500         400         125   

uge042

     4         0.22         SPHERICAL         0.31         15         10         15         0.27         55         60         90         0.2         500         400         125   

uge043

     4         0.22         SPHERICAL         0.31         15         10         15         0.27         55         60         90         0.2         500         400         125   

uge044

     4         0.22         SPHERICAL         0.31         15         10         15         0.27         55         60         90         0.2         500         400         125   

uge050

     5         0.137         SPHERICAL         0.538         50         50         62         0.015         90         180         220         0.31         600         450         500   

uge051

     5         0.137         SPHERICAL         0.538         50         50         62         0.015         90         180         220         0.31         600         450         500   

uge052

     5         0.137         SPHERICAL         0.538         50         50         62         0.015         90         180         220         0.31         600         450         500   

uge053

     5         0.137         SPHERICAL         0.538         50         50         62         0.015         90         180         220         0.31         600         450         500   

uge054

     5         0.137         SPHERICAL         0.538         50         50         62         0.015         90         180         220         0.31         600         450         500   

uge060

     6         0.2         SPHERICAL         0.593         35         55         55         0.135         110         160         100         0.072         1400         300         230   

uge061

     6         0.2         SPHERICAL         0.593         35         55         55         0.135         110         160         100         0.072         1400         300         230   

uge062

     6         0.2         SPHERICAL         0.593         35         55         55         0.135         110         160         100         0.072         1400         300         230   

uge063

     6         0.2         SPHERICAL         0.593         35         55         55         0.135         110         160         100         0.072         1400         300         230   

uge064

     6         0.2         SPHERICAL         0.593         35         55         55         0.135         110         160         100         0.072         1400         300         230   

uge070

     7         0.12         SPHERICAL         0.48         20         25         35         0.4         125         135         125         0.01         600         450         276   

uge071

     7         0.12         SPHERICAL         0.48         20         25         35         0.4         125         135         125         0.01         600         450         276   

uge072

     7         0.12         SPHERICAL         0.48         20         25         35         0.4         125         135         125         0.01         600         450         276   

uge073

     7         0.12         SPHERICAL         0.48         20         25         35         0.4         125         135         125         0.01         600         450         276   

uge074

     7         0.12         SPHERICAL         0.48         20         25         35         0.4         125         135         125         0.01         600         450         276   

uge080

     8         0.15         SPHERICAL         0.4         31         50         35         0.33         80         90         55         0.12         620         250         80   

uge081

     8         0.15         SPHERICAL         0.4         31         50         35         0.33         80         90         55         0.12         620         250         80   

uge082

     8         0.15         SPHERICAL         0.4         31         50         35         0.33         80         90         55         0.12         620         250         80   

uge083

     8         0.15         SPHERICAL         0.4         31         50         35         0.33         80         90         55         0.12         620         250         80   

uge084

     8         0.15         SPHERICAL         0.4         31         50         35         0.33         80         90         55         0.12         620         250         80   

uge090

     9         0.16         SPHERICAL         0.15         40         120         40         0.6         130         250         100         0.09         180         400         120   

uge091

     9         0.16         SPHERICAL         0.15         40         120         40         0.6         130         250         100         0.09         180         400         120   

uge092

     9         0.16         SPHERICAL         0.15         40         120         40         0.6         130         250         100         0.09         180         400         120   

uge093

     9         0.16         SPHERICAL         0.15         40         120         40         0.6         130         250         100         0.09         180         400         120   

uge094

     9         0.16         SPHERICAL         0.15         40         120         40         0.6         130         250         100         0.09         180         400         120   

uge100

     10         0.138         SPHERICAL         0.35         32         25         40         0.348         70         75         110         0.164         180         160         350   

uge101

     10         0.138         SPHERICAL         0.35         32         25         40         0.348         70         75         110         0.164         180         160         350   

uge102

     10         0.138         SPHERICAL         0.35         32         25         40         0.348         70         75         110         0.164         180         160         350   

uge103

     10         0.138         SPHERICAL         0.35         32         25         40         0.348         70         75         110         0.164         180         160         350   

uge104

     10         0.138         SPHERICAL         0.35         32         25         40         0.348         70         75         110         0.164         180         160         350   

From Monroy, 2011

 

 

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The variography results were discussed with the CMZ geology personnel while at the site. The nugget effect was determined from downhole variograms. It was approximately 12% to 22% for the oxide domains (UGE3 and 4) and 12% to 16% for the secondary sulphide domains (UGE7 to 9).

The directional variograms gave the ranges of continuity of the grades. The ranges are very long due to a slow rise from approximately 90% to 100% of the sill. Some examples of the modelled correlograms for the oxide and secondary sulphide composites are provided in Figures 14-9 and 14-10. RPA’s opinion is that the CMZ geostatistical analysis is reasonable and acceptable.

FIGURE 14-9 TCU CORRELOGRAM MODELS FOR UGE 3

 

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From Monroy, 2011

 

 

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FIGURE 14-10 TCU CORRELOGRAM MODELS FOR UGE 7

 

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From Monroy, 2011

RESOURCE ESTIMATION METHODOLOGY

The step by step resource estimation methodology is well described in Monroy (2011). The Vulcan C shell file (zald0511-1.csh) provides an excellent record of all the steps done in Vulcan to build the resource block model.

The Zaldívar mineral resource model extends from 91,030 m to 95,050 m East, 21,050 m to 23,500 m North, and 2,750 m to 3,710 m in elevation. The 5 m high by 15 m by 15 m block model is populated with the lithology, alteration, and mineralization codes and a separate script is run to assign the geological domain codes.

The capped assays were composited into five metre lengths. Remnant composites shorter than three metres were discarded. Composites for TCu, ASCu, and CNCu were created. The composite lithology, alteration, mineralization, and geological domain codes are back-flagged from the block model.

CMZ used multiple pass ordinary kriging (OK) to interpolate TCu and ASCu grades for all domains except UGE 1 and 2. The OK parameters were developed from directional

 

 

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variograms for each UGE. The search ellipsoids are generally sub-horizontal pancakes oriented at 040° to 050° with a small plunge (0° to 7°) to the northeast. The search radii vary for each UGE. The longest radii are 500 m by 500 m by 400 m for UGE5 (leached) and the shortest pass radii are 40 m by 30 m by 35 m for UGE3 (oxide). UGE1 and 2 are barren domains and the blocks are directly assigned zero grades.

There are typically five OK passes used for each domain in addition to the general box pass, which is always run first and is based on 7.5 m by 7.5 m by 2.5 m radii and a minimum of one sample and a maximum of three samples from a drill hole.

The first passes use a minimum of four composites and a maximum of eighteen composites, with a maximum of three composites per hole. The first pass radii are the distance defined by 80% of the omni-directional sill. The second and third passes use a minimum of four composites and a maximum of eighteen composites with a maximum of three composites per hole. They also use an octant based search with a minimum of two samples per octant and a maximum of three samples per octant, and a minimum of two octants with samples. The second pass radii are the distance defined by 90% of the omni-directional sill. The third pass radii are longer than the second pass radii. The fourth and fifth passes are the same as the second and third passes except that the minimum number of composites is reduced to two so that only one hole is needed. The multi-pass interpolation parameters are summarized in Table14-8.

 

 

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TABLE 14-8 %TCU ESTIMATION SEARCH ELLIPSE PARAMETERS

Barrick Gold Corporation – Zaldívar Mine

 

Estimation id

   UGE      Estimation
Type
   Bearing
(Z)
     Plunge
(Y)
     Dip
(X)
     Major Axis      Semi-Major Axis      Minor Axis      Min
Samples
per Est
     Max
Samples
per Est
     Use
Octant
Based
Search
     Max
Samples

per
Octant
     Min
Octants

With
Samples
     Min
Samples

per
Octant
     Maximun
Sample per

Drill Hole
 

box

      ID 2      0         0         0         7.5         7.5         2.5         1         99                     3   

uge011

     1       ID 2      50         0         0         65         65         40         2         3                     1   

uge012

     1       ID 2      50         0         0         130         130         65         2         3                     1   

uge013

     1       ID 2      50         0         0         520         520         65         2         3                     1   

uge030

     3       OK      40         7         0         40         30         35         4         18                     3   

uge031

     3       OK      40         7         0         70         55         65         4         18         1         3         2         2         3   

uge032

     3       OK      40         7         0         180         120         120         4         18         1         3         2         2         3   

uge033

     3       OK      40         7         0         70         55         65         2         18                     3   

uge034

     3       OK      40         7         0         180         120         120         2         18                     3   

uge040

     4       OK      50         7         0         40         40         40         4         18                     3   

uge041

     4       OK      50         7         0         100         80         60         4         18         1         3         2         2         3   

uge042

     4       OK      50         7         0         400         320         120         4         18         1         3         2         2         3   

uge043

     4       OK      50         7         0         100         80         60         2         18                     3   

uge044

     4       OK      50         7         0         400         320         120         2         18                     3   

uge050

     5       OK      50         7         0         150         110         120         4         18                     3   

uge051

     5       OK      50         7         0         290         220         250         4         18         1         3         2         2         3   

uge052

     5       OK      50         7         0         500         400         400         4         18         1         3         2         2         3   

uge053

     5       OK      50         7         0         290         220         250         2         18                     3   

uge054

     5       OK      50         7         0         500         400         400         2         18                     3   

uge060

     6       OK      50         7         0         30         40         40         4         18                     3   

uge061

     6       OK      50         7         0         65         80         65         4         18         1         3         2         2         3   

uge062

     6       OK      50         7         0         500         250         230         4         18         1         3         2         2         3   

uge063

     6       OK      50         7         0         65         80         65         2         18                     3   

uge064

     6       OK      50         7         0         500         250         230         2         18                     3   

uge070

     7       OK      40         7         0         40         45         45         4         18                     3   

uge071

     7       OK      40         7         0         75         80         75         4         18         1         3         2         2         3   

uge072

     7       OK      40         7         0         120         140         120         4         18         1         3         2         2         3   

uge073

     7       OK      40         7         0         75         80         75         2         18                     3   

uge074

     7       OK      40