narrow vein mining citicorp

Chris TowseyChris TowseyChief Operating Officer, Citigold Corporation LtdChief Operating Officer, Citigold Corporation Ltd

Narrow Vein Mining. CASE STUDY.Narrow Vein Mining. CASE STUDY.Citigold’s perspective on weighing up the Citigold’s perspective on weighing up the benefits against the challenges of narrow benefits against the challenges of narrow

vein miningvein mining

1000 km625 miles

4 kilometres

Railw

ay

Previous mining (yellow) developed200km of underground drives andproduced 6.6 million ounces of gold

Processing Plant

Tailings dam

Stockholmmine

Washingtonmine

Declineportal

0 1km

XWarrior

mine

Warrior Mine

Diagram from Peters, 1987. EGRU Contrib 19

No. 2 Cross Vein(Maude St. Leger reef)

No. 2 Cross Vein (Maude St. Leger reef)

Processing Plant

Tailings dam

Stockholmmine

Washingtonmine

Declineportal

0 1km

XWarrior

mine

Warrior Mine

Development PlanWarrior mine & gold resource – Long section

Development PlanWarrior gold resource – drilling Cross Section

Cross sectionLooking West

BENEFITS OF MECHANISEDBENEFITS OF MECHANISEDNARROW VEIN MININGNARROW VEIN MINING

Low mining cost per ounceLow mining cost per ounce–– low tonnage to break, haul and milllow tonnage to break, haul and mill–– high grade per tonne high grade per tonne –– 13 13 g/tg/t–– floor of drive preservedfloor of drive preserved

Mining method:Longhole open stoping10m sub-levels

Atlas Copco Simba

BENEFITS OF MECHANISEDBENEFITS OF MECHANISEDNARROW VEIN MININGNARROW VEIN MINING

Low mining cost per ounceLow mining cost per ounce–– low tonnage to break, haul and milllow tonnage to break, haul and mill–– high grade per tonne high grade per tonne –– 13 13 g/tg/t–– floor of drive preservedfloor of drive preservedSafer than handSafer than hand--heldheld

MechanisedCut and fill

Shrink stoping

Mining method:Longhole open stoping10m sub-levelsExpansion slot byvertical crater retreat

BENEFITS OF MECHANISEDBENEFITS OF MECHANISEDNARROW VEIN MININGNARROW VEIN MINING

Low mining cost per ounceLow mining cost per ounce–– low tonnage to break, haul and milllow tonnage to break, haul and mill–– high grade per tonne high grade per tonne –– 13 13 g/tg/t–– floor of drive preservedfloor of drive preservedSafer than handSafer than hand--heldheldAccurate grade controlAccurate grade control

9.6 g/t Au1.1 g/t Au 7.0 g/t Au

Grade variationGrade variation

No. 2 Cross Vein in stope pillarshowing rapid pinch-out

0.1m

0.2m

0.7m

CHALLENGESCHALLENGES

Dilution Dilution –– planned and unplannedplanned and unplanned

Planneddilution

Ore

Overbreak

Unplanned dilution

Cross section

Ore SortingDilution removed by ore sorting

Photometric ore sorter

The 30% waste and

dilution removed

by sorting

Feed screenedand washed

OREWASTE

CHALLENGESCHALLENGES

Dilution Dilution –– planned and unplannedplanned and unplannedMultiple working faces requiredMultiple working faces required

Conventional long-section view of a shoot within a planar structurePayability of structure 30%

Drill pierce pointsbelow cut-off

Drill pierce pointsAbove cut-off

Extraction levels

Charters Towers structure with payable areas – no defined shootPayability of structure 30%70% chance of a barren hole

Drill pierce pointsbelow cut-off

Drill pierce pointsAbove cut-off

Extraction levels

Stope blocks

CHALLENGESCHALLENGES

Dilution Dilution –– planned and unplannedplanned and unplannedMultiple working faces requiredMultiple working faces requiredFlatFlat--dipping stopes dipping stopes –– difficult muckingdifficult mucking

Stope cleaning of 10m x 20m panelswill use water-jets rather than scrapers

Ore is jetted down the stope to a gully or sump

Mining CostsMining Costs

222853352TOTAL COST 21844ADMINISTRATION 5202SURFACE HAULAGE

4517710PROCESSING 151582236Sub-total 7429623Development 77291613Production

MINING

Total$/oz

Total$/Tonne

Ore

Labour$/Tonne

Ore

Materials$/Tonne

Ore

Thank you