Mine Based Mine Based Pre-ConcentrationPre-Concentration

Ben MurphyCobar Mining Seminar - 9th August 2010

• Introduction – Technology & Challenges• Lean Mining and Waste Elimination• Pre-concentration – Suitability and technology• The Python Concept

Overview

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Mining Sector Issues

• Few “simple mining and metallurgy” large ore bodies left• Existing ore bodies –deeper and increasing complexity• Escalating capital on large fully engineered plants • High costs around developing smaller ore bodies• Long environmental permitting• Power and water supply issues

“Economies of Scale are great but what if the ore body is simply not big enough?”

Lean Mining Analysis

The Seven Wastes

Lean Mining Applied

(McCarthy, 1999)

Integrated UG Mining and Processing System Model (Bamber, 2004)

Mine Based Pre-concentration

Pre-concentration Benefits

• Reduced transportation costs– Haul distance – smaller equipment / less energy– Haul Mass – smaller equipment /less energy

• Smaller Inventories – Smaller higher value stockpiles

• Over processing– Valuable losses to fines– Savings in power and chemicals

TO MAXIMISE BENEFIT•MINIMISE DISTANCE TO MINING•MAXIMISE WASTE REJECTION

Pre-concentration Benefits

• Savings on mining costs of 20-50%

• Numerous studies in the literature to support this;– Bamber et al– Lane, Fountain & Brooy– Dominy, Gray & Daffern

Pre-concentration Benefits

• In addition– May allow alternate mining methods (narrow vein)– Backfill opportunities– Permitting benefits – May allow mining of small satellite ore bodies (surface)– Increase mine life – expand reserves

“For successful application integration into mining systems is critical”

Pre-concentration Technology

• Pre-concentration not a new thing• A rose by any other name…….. • Often applied at front end of the plant

Decreasin

g G

rade

Pre -concentration Technology

Suitability to Pre-concentration

• High grade into low mass – high gangue rejection• Coarse liberation• Mineralogical examination and lab test work

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Yield

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very

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Ag Distribution

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Yield

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very

Au Distribution

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Yield-Recovery Concept

Pre-concentration Methods

• Size Scalping and screening• Density Dense Media or Gravity• Colour / Fluorescence Optical / x-ray sorter• Magnetism Magnetic Separators• Surface Chemistry Coarse Flotation• Radioactivity Radiometric Sorters

Optical Sorting Flowsheet

Gravity - Flotation Flowsheet

Mine Based Case Studies

Company / Mine Metal Method Waste Rejection

Welsh Gold / Gwynfynydd* Au Gravity 98% +

INCO / McCreedy East PGM DMS 22-55%

Falconbridge / Thayer* Ni DMS 14%

Falconbridge / Fraser Cu Ore sorting 44%

Central Rand Gold / South Deeps* Au Gravity / Flash Flotation

90%+

* Operational Mine Based Pre-concentration sites

Selected Case Studies from Literature

Python – The Concept

Design Envelope– Fit in an UG drive– Transportable– Minimal Civils– Plug’n’play– Low water– Low power

Python – The Concept

13 Modules including MCC’s5 dry modules, 6 wet modules, 2 electrical

Designed for mobility and flexibilityPre-concentration focus

Python - The Reality

Mine Based Preconcentration

• Has the ability to provide step change improvements by;– Reducing mine transport costs– Reducing Inventories– Reducing Over processing

• To maximise its potential it is important to;– Minimise the distance from mine to plant– Maximise the waste rejection

• Potential savings of 20-50% of the mining costs

“Damit,….I don’t have time for this sales man, I Have a war on my hands”

Combined Size by Size Unit Gold

Recoveries of IPJ and Flash Flotation

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size um

% r

eco

very

flash

IPJ

Vertical Shaft Impactor (VSI)

• Rock fed into the top of the machine.

• Feed accelerated, leaves rotor at 60 m/s.

• Rock on rock crushing

• Handle large variation in moisture content, ideally suited wet screened products

• Can handle multiple feed sizes (30:1 reduction ratio)

Recovery from Gravity + Flotation

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