Explosives

What is an explosive?

Explosive is a solid or liquid substance or a mixture

of substances which on application of suitable

stimulus is converted in a very short time interval

into other more stable substances, largely or

entirely gaseous with the development of heat and

high pressure

Classification of ExplosivesLOW EXPLOSIVESDeflagrate rather than detonate, Low reaction velocity, no water resistance, highly flammable, very sensitive, 2,000-5,000 FPS EG, black powder

HIGH EXPLOSIVESCan be detonated by

blasting cap

DYNAMITESComposed of nitro glycerin &

filler material

GELATIN DYNAMITESCombination of nitroglycerine

& nitrocellulose.

SEMI GELATIN

STRAIGHT GELATIN

AMONIA DYNAMITESAmmonia nitrate substituted

WATER GELS, SURRIES & EMULSIONSCan be classed as high explosives or blasting agent, depending on

its cap sensitivity & chemical composition mixture of oxidizers, fuels and sensitizers which contain 5-40% water. Available in a wide range

of densities, commonly packed in polyethylene tubing excellent water resistance.

TWO COMPONENTEach individual component is non explosive can be shipped by any

means.

BLASTING AGENTSCombination of oxidizer and fuel,

cannot be detonated by just blasting cap.

BULK MIXED COMPOUNDSAmmonium Nitrate and fuel oil mixed on the job by the consumer;

very economical, good fumes if mixed properly; no water resistance.

PRE-MIXED NCNNitocarbonitrate mixtures prepared by manufacturer, light density,

no water resistance.

STRAIGHT DYNAMITESweight strength is equivalent

% of nitro glycerin.

SPECIAL GELATIN

Velocity of Detonation 2000 to 7000 m/s

Pressure

>1800 GPa

Temperature

3000o K to 4000o K

Pressure in a blast hole can exceed 10 GPa (100,000

atm) sufficient to shatter the rock near the hole, and

also generate a stress wave that travels outward at

a velocity of 3000 to 7000m/sec.

Explosive Classification

• Initiation Explosives

• Low Explosives.

• High Explosives.

• Blasting Agents

Initiating explosives are used in small

quantities to initiate detonation in larger and

less sensitive high explosives. They are

supplied in copper or aluminum tubes to

form detonators, or are used in detonating

cord.

Initiating Explosives

Low Explosives

• Blasting or black powder. Used for dimension

stone work, will heave the stone rather than

fracture it.

• Splitting products. Usually are of plastic

construction and have blasting powder in

them. May be fired by a fuse head inserted

like a primer in a rifle cartridge.

NG-EXPLOSIVES

SOME SLURRY

SOME EMULSIONS

SPECIAL PRODUCTS

High Explosives

Blasting Agents

ANFO

SOME SLURRY

SPECIAL PRODUCTS

YEAR DEVELOPMENT

13th Century

Mention of saltpeter and other blasting powders in Arabian and Chinese writings

1242 Black powder formula by Bacon

1846 Sobrero discovered nitroglycerine

1861 Alfred Nobel sets up nitroglycerine plant

1866-75 Dynamite and Blasting gelatine commercially manufactured

1880's Permissible Dynamites investigated

1950's Ammonium Nitrate and combustibles as dry powders (ANFO)

1957 Watergel (Ammonium Nitrate, TNT and Aluminum powder)

1964 Emulsions (Emulsified Ammonium Nitrate and Nitric Acid)

1969-74 Watergel (Mono Methyl amine Nitrate, or Hexamine Nitrate or Aluminum powder)

1979-82 Heavy ANFO (Up to 50% Emulsion and ANFO)

Significant Developments In Commercial Explosives

Nitroglycerine (NG), a major component of The

dynamites, when in pure form, is relatively unsafe

and sensitive to impact. Straight dynamites contain

20 - 60% nitroglycerine. They have poor fume

characteristics. Ammonia dynamites have largely

replaced straight dynamites.

Nitroglycerine Explosives

Gelatines contain liquid

nitroglycerine with

nitrocellulose supplied as

cartridges or "sticks".

NOW DISCONTIUED IN USAGE

Nitroglycerine C3 H5 (ONO2) 3

AMMONIUM NITRATE FUELOIL (ANFO) and Other Blasting Agents

Ammonium nitrate (AN), mixed with fuel oil

(FO) in the ratio of 94.5:5.5 by weight.

NH4N03+CH2→3N2+7H20+C02+967 kcal/kg

ANFO is the least expensive

explosive available. When

correctly used, ANFO performs as

well as dynamites and is much

safer. However, it absorbs water

hence, it cannot be employed in

wet conditions. Density is low.

Mixing ANFO• When mixing ANFO the following sign must be

displayed:

DANGER EXPLOSIVES

NO SMOKING OR FLAME

• No source of flame or spark must be brought within 10 metres of the operation.

• If any ANFO is left over, then it must be stored in a Licensed Magazine.

• It be placed in a sealed, leak proof, non metallic container.

• This container be labelled, “EXPLOSIVES MIXTURE”.• This ANFO will be used as soon as practicable.

NG EXPLOSIVES ?

SLURRY ?

ANFO ?

Cartridge Explosives

Slurries Ammonium Nitrate (AN) slurries and emulsions have been developed for blasting in watery conditions. AN with sensitiser, combustible material and thickener + 20% Water produced as slurries, gels and emulsions.

Much higher pressureWaterproofHigher VODDenserCan be pumped.

Costs are higher than ANFO

Slurries Composition

• OXIDISERSSuch as AN, SN or CN

• FUELSOIL

• SENSITIZERSChemical - Organic Amines, Perchlorate Salts, Small Particles of AL

Physical - Entrapped Air Bubbles

ADVANTAGES

Packaging Cost SavedLoading rates much fasterBetter CouplingRigid quality specifications variable

SUITABILITY

Normally suited for large operations. Shared services for smaller operations.Schedule to be arranged and also size of shot to be tailored to suit capacity of trucks.Increased coupling allows larger charge per hole but may cause vibrations at times.

BULK MIX TRUCKS OR ANFO TRUCKSMix and deliver AN/FO/AI Powder

Bulk Loading System For Explosives

Bulk Trucks (Site Mix Trucks)

Raw materials for making

explosives like AN, SN solutions

from support plant, are carried in

trucks and explosive mixed at site.

Pump Trucks for delivery of plant-

mixed slurry or emulsion.

Bulk Trucks

ANFO in dry hole application, low cost

and easy mixing but has low density and

unsuitable in wet holes

Bulk Explosives

Special explosives are needed for controlled

blasting, underwater blasting, and blasting of

high temperature rock.

PIPE CHARGES

LOW ENERGY EXPLOSIVES

PRODUCT WITH VARIABLE ENERGY

Special Application Explosives

Cast Primers

• These are made from a mixture of PETN and TNT.

• Are used to initiate bulk explosives.

• Have a very high VOD.

• They have a high density of 1.5 and readily sink in water.

PRIMERS

MIXTURES OF PETN AND TNT, HIGH DENSITY 1.6 g/cc TO 1.7 g/ccDetonation velocity 7000m/s

INITATED BY SHOCK TUBE AND DETONATOR, DETONATING CORD

CAST BOOSTERS

Their high strength, high density and very high velocity of detonation (7000 m / s) make them suitable for priming ANFO mixtures and slurries. An additional advantage is their lower sensitivity to shock, friction and impact. explosives.

RELIABLY INITIATE BULK

Medical AspectsNow a days more consideration given to

medical aspects

Less toxic gases

Non-headache producing explosives

For opencast workings not much problem

For underground workings carbon monoxide, oxides of nitrogen and fumes are kept within acceptable limits

Some explosives cause skin irritation and eczema