Cook Open Pit Model – The Hurdles: How We Leapt, Lunged, Stumbled, and Overcame Them

K Dudgeon, J Paradis, M Topping

Important Note

Newmont sold its Jundee Operation to Northern Star Resources

Limited on 1 July 2014.

Information contained in this presentation and corresponding

paper ‘Cook Open Pit Model – The Hurdles: How we Leapt,

Lunged, Stumbled and Overcame Them’ by K Dudgeon,

J Paradis and M Topping was prepared prior to the sale of the

Jundee Operations. Newmont makes no representations as to the

accuracy or reliability of the information contained in this

presentation and information regarding ore bodies is used with

the permission of Northern Star Resources Limited.

Cook Open Pit Model: The Hurdles 2

Location

Cook Open Pit Model: The Hurdles 3

Ore Characteristics

Cook Open Pit Model: The Hurdles 4

Plan Section West-East Section

Low Grade

High Grade

Narrow vein multi lode gold system with general N-S strike.

Increased presence of LG halos

around narrow HG veins in oxide

and transitional zones.

Main High Grade Cook Lodes

Hurdles we overcame…

Modelling methods

•Use of multiple methods for one estimate

Compositing and statistics

•Multiple drill types and mineralisation styles requiring different

compositing methods

Grade estimation

•Underground to Open Pit mindframe

Personnel

•Limited staff available and no open pit geology department

Cook Open Pit Model: The Hurdles 5

Modelling Methods

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Implicit Leapfrog

modelling

Vulcan section

polygons

Vulcan categorical

modelling

Drilling indicator value

0 - <2 (Not HG)

2 (HG)

1. Implicit Leapfrog modelling

What it was used for?

•High grade veins

•Lithology and faults

Why it was used?

•Dataset and interpretations already in place from exploration

model

•Easy and quick to manipulate and update the original data

•Suitable method for the narrow, generally linear and continuous,

high grade veins

Cook Open Pit Model: The Hurdles 7

Implicit Leapfrog modelling

Cook Open Pit Model: The Hurdles 8

Another screen capture?

2. Vulcan section polygons

What it was used for?

•Shallow data in the oxide and transition zone

•Simple lithologies requiring more constraining than Leapfrog

processes could provide

•Low grade halo around certain continuous high grade lodes.

•Small discontinous lodes

Why it was used?

•Allowed more control over the detailed shape of the grade halos

and some intrusives

•Easier review and adjustment of interpretation

•Most common technique used on site

Cook Open Pit Model: The Hurdles 9

Vulcan section Polygons

Cook Open Pit Model: The Hurdles 10

lode ck701

section polygon

CROSS SECTION

Low grade halo wireframe using section polygons

3. Vulcan categorical modelling

What it was used for?

•Low grade mineralisation zones

•Established validity of trends for use in making high grade

polygons in the oxide and transition zones

Why it was used?

•Alternative method to Leapfrog for quickly determining trends

•Efficient way to define wide irregular zones of mineralisation over

a large area

•Created an unbiased 3D interpretation where required

Cook Open Pit Model: The Hurdles 11

Vulcan categorical modelling

Cook Open Pit Model: The Hurdles 12

Establishing high grade trends for section polygon modelling Low grade that is not part of a high grade halo

Creating low grade halos

Block model

indicator value

Drilling indicator value

0 - <2 (Not HG)

2 (HG)

Drilling indicator value

0 - <2 (Not HG)

2 (HG)

Categorical Block model

and drilling using indicator value Categorical grade shell

and drilling using indicator value

A B

C

Modelling Method Summary

Cook Open Pit Model: The Hurdles

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Use Advantages Disdvantages

Leapfrog Implicit

Modelling

• Quick process and easily updated

• Leapfrog dataset and file already established

• Quickly and easily visualise trends

• Great for tight, linear trends with smaller

datasets

• Can adjust smoothing of triangulation

• Can produce large file size wireframes

• Harder to constrain shapes/trends

• Snapping issues when bringing back into

Vulcan

Vulcan Section

Polygon Modelling

• More control over interpretation

• Easily adjusted and re-wireframed

• Compatible with blocking and compositing in

Vulcan

• Can be slower and more labour-intensive

than Leapfrog

Vulcan Categorical

Modelling

• Good for larger data set and/or irregular

lithologies

• Another way to check validity of trends

• Creates large file size wireframes with

occasional closure/integrity issues

General Learnings

Validation is everything! The creation of new procedures, and ways of

managing data highlighted that validation was critical.

Categorical modelling proved to be a useful tool in defining trends and

interpretations encompassing larger areas, and has since been

incorporated into resource modelling and exploration processes.

Combining the skills of multiple geologists can significantly improve the

execution of a project and increases the awareness of available

methods, which can then be implemented in other areas.

The adaptability of both personnel and processes proved key to the final

outcome and ongoing improvements within the geology departments.

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THANK YOU

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