ISMR Technology Transfer Seminar ANFO & Emulsion Characteristics Heavy Blends as a Tool for Blasters!

ISMRTechnology Transfer

SeminarANFO & Emulsion

CharacteristicsHeavy Blends as a Tool for

Blasters!

What is needed for an explosion?

ANFO

• Ammonium Nitrate / Fuel Oil• Ammonium Nitrate Production

– Reaction of anhydrous ammonia gas and concentrated nitric acid.

– After the reaction the AN solution is about 83% concentration.

– Excess water is evaporated off to leave an AN concentration of 95 to 99.9%.

AN Production cont’d

• AN Solution is turned into prill. – A small percentage of water is left in the

solution when the prill is formed.– When the prill is dried the water is

removed and it leaves voids in the prill.– This is where the diesel fuel goes when

added to the prill.

ANFO Characteristics

• ANFO Density ranges from .82 - .90 g/cc• Oxygen Balanced @ 94.4% AN / 5.6%

Fuel• Under fueling leads to:

– Greater sensitivity.– Drastic loss of ENERGY! – Orange smoke, inefficient reaction during

detonation. • Over fueling leads to:

– Loss of Energy.

Effects of Fueling on Fume Production

http://www.cdc.gov/niosh/mining/pubs/pdfs/faafp.pdf

Effects of Fueling on Fume Production

http://www.cdc.gov/niosh/mining/pubs/pdfs/faafp.pdf

Effects of Fueling on Energy Output

ANFO and VOD

• ANFO VOD increases as the borehole diameter increases.

Borehole Velocity of ANFO

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

Borehole Diameter (inches)

VO

D (f

t/sec

)

ANFO Characteristics

• The critical diameter of poured ANFO is about 2.0 – 2.5 inches.

• Under this it will not detonate.• If it is loaded pneumatically the critical

diameter can be increased to 1.0 inch.• ANFO is considered a ‘Blasting Agent”

– This means it cannot be detonated with a #8 strength detonator when unconfined.

– It requires a primer assembly to be initiated.

ANFO Characteristics

• When ANFO detonates it does so inefficiently.

• This produces excess gases from the reaction.

• This is a benefit to blasting due to the rapid expansion of the gases out into the formation creating a “heave” effect.

• This heave effect allows for easier digging.

ANFO Characteristics

• ANFO is not waterproof or even resistant.• ANFO can deflagrate if a significant amount

of water has damaged the ANFO. • ANFO can fail to detonate if water has

damaged enough ANFO in the hole.• If the ANFO shoots “low order”, it shoots

inefficiently and produces excess gases. – Orange fumes!

Emulsion

• Water solutions of oxidizers in an oil medium. (ISEE Blasters Handbook:

Chapter 7, page 77.)

• A mixture of two or more liquids in which one is present as droplets, of microscopic size, distributed throughout the other.

Explosive Emulsion Anatomy

• Oil continuous, “external” phase (green) – 5 to 9%– Mineral oils– Diesel fuels– Recycled oils– Vegetable oils

• Aqueous salt discontinuous, “internal” phase (blue) – 91 to 95%– Ammonium Nitrate– Calcium Nitrate– Sodium Nitrate– Perchlorates

Bulk Emulsion Characteristics

• Typical density of a sensitized emulsion runs about 1.25 g/cc.

• Loaded in diameters between 1and 12 inches.• VOD increases with Borehole Diameter.• Sensitivity/density can vary with the addition of

microballoons or chemical gassification.• Can be dead pressed when sensitized with

microballoons. (Crushing of balloons)• Can be classified as Oxidizer of Blasting Agent.

What are Heavy Blends?

• Blends of ANFO and Emulsion

Heavy ANFO Blends

• Why utilize blends?– Increase the density of ANFO; hence,

increase energy in the borehole– Provide water resistance to ANFO– Reduce mining costs

(ISEE Blasters’ Handbook; Chapter 9, page 93.)

Heavy ANFO Blends

Emulsion/Blend Properties

Emulsion/Blend Properties

Generic Cost

Comparison

Blend Benefits

• Longer sleep times with heavy blends.• Water resistance for ANFO in wet

formations.• Pattern expansions.

– Maximize energy in hole.– Drill cost savings potential.– More production yards per hole.– Less shots per cut.

ANFO Shot

Gassed Emulsion

Gassed Emulsion

Blend Shot

Blend Shot

Blend Shot

Blend Shot