Evaluation of Grade Engineering® using Enterprise Optimization

Michael Scott, Nick Redwood

Not for Profit Research Organization

Site implementation of step-change innovation

– Grade Engineering®– Integrated Extraction Simulator– Mining innovation hub

www.crcore.org.au

Consulting professionals

Holistic business optimization service for strategic mine

planning

– Enterprise Optimization– Money Mining Workshops

www.whittleconsulting.com.au

Who we are

Grade Engineering®

Concentrator

Leach/Waste

Grade Engineering applies coarse separation techniques to:

• enhance the quality of ore processed• improve material allocation decisions• increase the value of the asset• reduce energy, emissions and water

intensity of metal production

• remove uneconomic material from ore• recover economic material from waste, or• exchange high-value and low-value

fractions between processing destinations

Strategic Planning Complexities

Waste

Heap Leach

Stockpile

Processing Plant

Mining

Block Model Direct Feed

Higher Value

Grade Engineering

Lower Value

Metal and material trackingCapacity constraints Upstream/downstream impacts

Enterprise Optimization Increasing the value of mining and mineral processing operations through

better long-term planning decisions

– Holistic business optimization service for strategic mine planning

– Links strategic decisions (and impact) across operational components

1. Customizable process flowsheets

2. Activity based costing

3. Theory of constraints

Key Benefits

Project

Demonstrate the ability of Enterprise Optimization to incorporate and evaluate the principles of Grade Engineering

Marvin deposit; hypothetical but realistic case study

Three Grade Engineering techniques:

1. Natural deportment2. Differential blasting3. Bulk sorting

Scope

Case Study

Test

Natural DeportmentCertain mineralizations exhibit a natural tendency to concentrate valuable

minerals in finer size fractions during blasting and crushing

Cut-offCut-off

Differential BlastingDifferential blasting adjusts the design within a blast to achieve finer

fragmentation in high-grade and coarser fragmentation in low-grade.

Bulk SortingOre sorting uses quantitative or indicative sensor measurements of grade to decide whether to accept or divert material at transfer points within mining

and mineral processing activities.

Delivered grade heterogeneity, sensor performance and separation efficiency

Case Study: the Deposit

• Cu-Au porphyry

• Higher Au grades at shallow elevation

• Higher Cu grade at depth

• Six geometallurgical processing domains

• Hypothetical but realistic deposit

Gold Grade

Copper Grade

GradeAu (g/t)Cu (%)

Case Study: the Operation• Open pit mining method

• Processing plant (SAG, ball, flotation)– 4 grind sizes (tph, recovery,

grinding media costs)

• Heap leach

• Stockpiles

• Grade Engineering– Screening Plant

– Cross belt analyzer (post primary crusher)

Process Flowsheet

Waste

Heap Leach

Stockpile

SAG Mill

Processing Plant

Flotation

Ball Mill75μm Grind

100μm Grind

150μm Grind

200μm Grind

Product

Tails

Product

Tails

Mining

Block Model

Direct Feed

Fines

Coarse

Screening Plant

Differential Blasting

Natural Deportment30mm Screen

50mm Screen

75mm Screen

100mm Screen

150mm Screen

Accept

Divert

Bulk Sorting20% Accept

40% Accept

60% Accept

80% Accept

Scenarios

$620

$630

$640

$650

$660

$670

$680

$690

$700

Base Case + 1 GradeEngineeringTechnique

+ 2 GradeEngineeringTechniques

+ 3 GradeEngineeringTechniques

Net

Pre

sent

Val

ue (U

S$ M

illio

ns)

Scenario

Differential Blasting -> NaturalDeportment -> Bulk Sorting

Differential Blasting -> BulkSorting -> Natural Deportment

Natural Deportment -> BulkSorting -> Differential Blasting

Natural Deportment ->Differential Blasting -> BulkSorting

Bulk Sorting -> NaturalDeportment -> DifferentialBlasting

Bulk Sorting -> DifferentialBlasting -> Natural Deportment

Differential Blasting

Differential Blasting +Bulk Sorting

All

Operational Impact• Mining rate increased

– Mining finished 2 yrs earlier

– LOM not significantly reduced

• Increased use of the stockpile

• Greater proportion of finer grind/ higher recovery

– Processing plant closed 1 yr earlier

– more metal recovered

• Cut-off grade – Increased in earlier years

– Decreased in later years

• Energy intensity of metal production decreased by 7%

0.00

0.20

0.40

0.60

0.80

0.0

1.0

2.0

3.0

4.0

5.0

6.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Cu G

rade

(%)

Au G

rade

(g/t

)

Ore

(Mt)

Year

0.00

0.20

0.40

0.60

0.80

1.00

0.0

4.0

8.0

12.0

16.0

Cu G

rade

(%)

Au G

rade

(g/t

)

Ore

(Mt)

Heap Leach

Processing Plant

Value of Grade Engineering

Coarse separation:• Upgraded material improves the grade

processed at bottlenecks

• Removing low-value material from bottlenecks increases capacity to treat higher value ore

Supported by:• Metal Exchange – low-value fractions are

‘exchanged’ with high-value fractions

• Increased mining rate – higher proportion of mined material can be Grade Engineered

• Stockpiles – defer the treatment of lower value material

Conclusion

Enterprise Optimization was successfully demonstrated as an effective methodology to evaluate Grade Engineering strategies

• All coarse separation techniques improved the value of the operation

• Benefits of each technique were not cumulative

– Coarse separation techniques competed for treatment of the same material

• Grade Engineering produced greater value by

– increasing the cut-off grade in earlier years; accelerating metal recovery

– Decreasing the cut-off grade at the end of the operation; expanding reserves and improving resource utilization

• Supported by increased mining rate, stockpiling and metal exchange

• Further details: www.crcore.org.au or www.whittleconsulting.com.au

Questions?

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