Recent Innovations in Perimeter Blasting

Ontario Mining Health and Safety Conference Sudbury – April 18, 2013

Development Blasting – Perimeter Control

• Context– Perimeter control refers to additional measures taken in the

outside holes of a development round to reduce the impact of blasting on the surrounding rock mass. Good perimeter control lowers scaling and bolting time, decreases over break and reduces reconditioning.

• Orica HandiLoader System• PowerGel Viper

Perimeter Control

• The act of reducing the impact of the explosive detonation pressure inside the borehole and on the surrounding mass.

Explosive Energy

Detonation YieldsShock Energy + Gas Energy…

... that Breaksand Heaves Rock

shock sensor 1m from borehole center

Trace height indicatesintensity of shock wave

6-inch diameter boreholeexplosive fully coupled

2-inch diameter boreholeexplosive fully coupled

6-inch diameter boreholewith 2-inch diameter charge

air space around charge

water in space around charge

6-inch diameter boreholewith 2-inch diameter charge

Effects on Shock Wave

HandiLoader String Loading System

Orica String Loading System

A combination of specific products and PLC controlled equipment resulting in a variable speed retraction system for the charging hose, designed for minimising damage in the back and side walls.

Constant pumping velocity c [kg/s]

Controlled retraction speed v [m/s]

Q = c/v [kg/m]

Bulk Emulsion Explosive• Water in Oil Emulsion

– External oil phase is water repelling (Water resistant)

– Water Phase• Oxidiser Solution

– Nitrates (70-80%) + Water (20-30%) + Minor Chemicals

– Fuel Phase• Readily available oils

including diesel, paraffin oil, vegetable oils or wax’s (Packaged)

• Emulsifiers/ChemicalsDual Sensitized/Variable Density

Equipment

• Emulsion Pumping Unit.

• PLC Control Unit• Hydraulic Hose

Handling System• In-Basket Operator

Controls

Charging Unit Illustration

Instrumentation

Charginghose

Dosagepump

WaterGassing agents

Emulsion

Dosagepump

Main pump

Mixingnozzle Homogenizer Hose Retraction

100 %

50 % reduction

75 % reduction

Flexible Charging Density

HandiLoader String Loading System

Universal Explosive - Different Charging DensitiesApplication

Distribution of charging densities in a typical road tunnel (45 mm drill bits):

Cut

Stoping b

Lifters

Stoping a

Wall Wall

Contour

Internal ContourUp to 5 pre-programmed loading density options

Glass Tube Loading

40mm (0.25m/sec)

32mm (0.40m/sec.)

22mm (0.83/sec.)

22mm (0.83/sec.)

32mm (0.40m/sec.)

40mm (0.25m/sec.)

Features & AdvantagesSafetyReduces peak pressure and rock over break through string chargingReduced crack zone/damage to surrounding rock structureNo risk of pull-outs or blow-out as experienced with packaged productsVariable densityAllows to reduce energy density in holeAllows complete flexibility of charge from 25% to 100% of hole volume

EfficiencyShorter charge time (up to 50% less time compared to cartridge explosivesCharging documentation generated by system

CostLower overall cost per round of explosivesConsiderably cheaper than conventional perimeter products

HandiLoader String Loading System

Benefits Identified in Local Trials• Compared to conventional packaged

explosives– Over-break reduction – 6% Average– Finer Fragmentation (95%<16in vs. Anfo @ 32in)– Reduced Damage to Services – 50%– Reduction in Bolting Required – 6.6%– Muck Pile Height/Profile and Cast– Cycle Time Reduction– Advance Rate – Equal or better– Explosives Cost Reduction – (13 – 24%)

Benefits Identified in Local Trials

• Compared to conventional packaged explosives– Post blast Ventilation Time – Reduction in

Ammonia – Re-blasting Costs – reduced misholes– Loading Efficiency – vs. Packaged Explosives – Reduction of Manual Labor –vs. packaged– Product rationalization – no need for specialized

products– Ability to adjust powder factor and blasting

process for specific rock type

Over Break Reduction

Traced Anfo String Loading

Fragmentation

Anfo String Loading

Example of MacLean Loader Conversion

Example of IFI MineCat

Boom Basket – Large Headings

Example of IFI MineCat

Man-lift– Narrow Vein – used in 10x12ft

Orica PowerGel Viper

Packaged Perimeter Control Product

PowerGel Viper •Product aims to deliver an easy to use perimeter control product.•Good wall control product for a positive impact where miners spend ~50% of their time in the scaling and bolting cycle. •Based on accepted Razorback concept.

•Improved toe design•Improved explosive formulation•Improved retention device

•The lack of detonating cord differentiates itself from other products

PowerGel Viper

Product Characteristics•Precut length – 14 ft•Watergel explosive formulation (Detagel)•Density – 1.20 g/cc•VOD – 5000 m/sec•Toe Charge Design

PowerGel ViperSafety•Low impact sensitivity compared to other perimeter control products•Engineered detonator well•Detonator locked in and ideally located within the explosive charge•Stabilization in the blasthole provided by a spider locking device•Highly visible•Decoupled charge minimizes damage to back and wallsEase of Use•A single pre cut piece – no assembly•Improved priming•One piece design•Higher toe charge

Any questions?