3 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%.
4 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.
5 ANFO Characteristics ANFO Density ranges from .82 - .90 g/cc Oxygen 94.4% AN / 5.6% FuelUnder fueling leads to:Greater sensitivity.Drastic loss of ENERGY!Orange smoke, inefficient reaction during detonation.Over fueling leads to:Loss of Energy.
9 ANFO and VODANFO VOD increases as the borehole diameter increases.
10 ANFO CharacteristicsThe 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.
11 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.
12 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!
13 EmulsionWater 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.
14 Explosive Emulsion Anatomy Oil continuous, “external” phase (green) – 5 to 9%Mineral oilsDiesel fuelsRecycled oilsVegetable oilsAqueous salt discontinuous, “internal” phase (blue) – 91 to 95%Ammonium NitrateCalcium NitrateSodium NitratePerchlorates
15 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.
16 What are Heavy Blends?Blends of ANFO and Emulsion
17 Heavy ANFO Blends Why utilize blends? Increase the density of ANFO; hence, increase energy in the boreholeProvide water resistance to ANFOReduce mining costs(ISEE Blasters’ Handbook; Chapter 9, page 93.)
22 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.