Adrian Dance, PhD, PEng, FAusIMM

Principal Consultant – Metallurgyadance@srk.com

Metallurgical Testing Methods to Evaluate Pre-concentration

What is your ore hiding from you?

Mine

Plant

Dynamic Ore Scheduling

Waste ???

Current Mindset – Revisit the Mine-Mill Interface

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Mine Plantore

waste

• different flowsheet• modified flowsheet

(campaign)

100% of feed goes to plant• same power intensity• same water intensity• same tailings storage method

Plant 2

Stockpile

Ore???

Opportunities

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OREORE

WASTE

OREORE

WASTE

WASTE

ORE

Primary Crush

SAG Mill

HPGRDecisions can be made as often as every 30 seconds

Need for Standardised Testing

We are not currently evaluating coarse, waste rejection

Waste not Ore Characterisation

Bulk properties– hardness, grade vs. size, density

Exploit differences waste vs. mineralised material– grade deportment by size– hardness– specific gravity– appearance/colour

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Technological Convictions for Met Testing

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At the start of any study, the following should be considered TRUE

1. heterogeneity of ore/waste boundaries can be estimated and exploited as part of the mining process (before arriving at the plant)

2. geometallurgical domains will reveal unique properties to be separately scheduled by the mine and/or processed under different plant conditions

• domains based on economics: cost per tonne vs. revenue (i.e. recovery)

3. pre-concentration methods will be adopted as standard practice to improve feed quality

Drillcore Scanning – Heterogeneity

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Average grade across this interval

What Should We Do?

Testwork procedures changed to consider current technology– technology available to assist decision-based processing

Stop stage-crushing as the first stage of preparation– XRF logging of contiguous intervals– primary crush size-by-size analysis (jaw crusher vs. impactor)– modified comminution tests

Prioritise coarse, dry processing options– metal deportment vs. particle size (valuable & impurities)– identify distinct metallurgical domains

• grade deportment & mineralogy

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• Define geomet domains

• Generate Opex vs recovery curves for each domain

Testwork Program – Bulk Sample

Develop met domains based on bulk characteristicsTHEN evaluate separation/recovery options

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mineralogy

grade

hardness

specific gravity/ photo

Original Samples

Low-energyCrush

Ore

Waste

Testwork Program – LaboratoryModified Comminution Testing– break range of particle sizes at different energy levels– larger particles broken at crusher specific energies– assay products as well as size them

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Why perform a test and only measure

one response?

Scale-up from Lab Testing

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Simulate Metal Deportment

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low-energybreakage

screenupgrading

monitorreject stream

particlesorting

Estimate mass split and metal deportment at each stage

Summary

Testing needs to characterise coarse, waste properties– for gold projects 999,999 parts of ‘ore’ need to be characterised

Commit to follow the technological convictions– exploit heterogeneity, geomet domains and pre-concentration opportunities

Plan for ore/waste segregation– by-product streams of rejected/diverted material

Revisit the Mine-Mill interface for the next step change– dynamic ore scheduling– campaigning of geomet domains

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