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Black Powder Blasting?

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EC Therapy

Dec 1, 1998, 3:00:00 AM12/1/98
I was curious as to the methods used decades ago to blast holes for
rail roads, soft dirt for ditches, etc. I have read many historical
notes about the use of BP instead of Dynamite due to cost factors,
stability at the time ( of the HE ), and portability of powders.
Does anyone have any information? I was curious as to how much work
was involved in drilling the holes that were needed to place a large
enough powder charge to shatter rock... it does seem to be very
labor intensive. Also, how would the charges be kept dry in the
case of digging in earth? Were most blasting type powders similar
to the black rifle powders, or did they use sodium nitrate instead
of potassium nitrate ( hence, the moisture issue ). What volume of
powder was required for moving earth, splitting rock ( shale or
other soft rock ), etc... At what time period did the use of
Dynamite, blasting gelatin, or other HE become common practice, with
the phasing out of the BP methods?

I appreciate the info!



Dec 1, 1998, 3:00:00 AM12/1/98

EC Therapy wrote in article <>...

Wow! Ok, you want the history of explosives in a nutshell. Got a couple of
If you want a detailed history, check out your library and do a search for
explosives/ mining techniques. However, I'll try to answer a few of your
Until the 1860's blackpowder was the only explosive availible for hard rock
blasting. Yes, drilling the shot holes was labour intensive.( See the poem:
"John Henry was a Steel Driving Man") It involved a team of two men, one
holding the drill or "steel" , the other wielding a sledge hammer.
Basically, the procedure was: hit steel with hammer, turn steel a 1/3 or
1/4 turn, hit steel with hammer, etc. etc. until shot hole was deep enough.
In the late 1800's the pneumatic drill, working off steam or later,
compressed air, was employed. An Italian named Sobrero first produced
nitroglycerine (glyceryl nitrate, glycerol trinitrate, etc) in 1847.
It was used in the early 1850's for blasting purposes, but was found to be
too unpredictable for practical use. Alfred Nobel absorbed nitroglcerine in
a type of earth called keiselguhr and patented the product in 1867 as
dynamite. About the same time, the first crude blasting caps were patented,
and the blasting industry took off. In more ways than one. Dynamite may
have been "relatively safe" but you still had to have plants producing the
basic ingredient. Further developments involved mixing the niroglycerine
with sodium nitrate, gelling it with nitrocellulose, and later, replacing a
large part of the nitroglycerine with ammonium nitrate. TNT and other
military type explosives were not used much in commercial blasting due to
the cost. TNT or TNT/PETN (Pentolite) mixes are used as primers for
insensitive medium velocity blasting explosives such as ANFO or ANFO based
water gels, Nitro Carbo Nitrates, etc. There are literally thousands of
types/brands of blasting explosives produced today. Most are ammonium
nitrate based, except for special purpose high velocity explosives for
techniques like face shearing.
Back to black powder. Sodium nitrate was used as a substitute for potassium
nitrate only because it was much cheaper. All black powder is hygroscopic,
sodium nitrate based powder is much more so. Graphite glazing of the bp
grains was used to reduce the effects of moisture and give a free flowing
powder. It is still used in the commercial production of bp.
'Nuff said on this, I have to go to work. Hope this helped.
semper mint...ah what the hell....

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