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Патент USA US3026231

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Patented Mar. 20, 1962
the examples are parts by weight, unless otherwise desig
nated. The TNT pellets used in the exempli?ed experi
ments were a commercially available material termed
William E. Kirst, Woodhury, N..l., assignor to E. l. (in
Pont de Nemours and Company, Wilmington, Deh, a
corporation of Delaware
Mo Drawing. Filed .lnly 21, 1958, Ser. No. 749,632
2 Claims. (Cl. 149-39)
pelletol comprising free-?owing water-resistant pellets
of TNT substantially spherical in form.
Example 1
Into a mixer of the type conventionally used in the
preparation of explosive compositions were charged 4000
The present invention relates to a novel blasting com
parts of the TNT pellets and 6000 parts of sodium nitrate
position which is of high density. More particularly, the
present invention relates to a high-density blasting com- 7
of a commercial grade having the following ?neness speci
position comprising low-cost ingredients.
In blasting operations, for example quarrying and strip
Tyler standard screens:
ping, the use of a high-density explosive composition is
On 10 mesh _____________________ __ 2.0% max.
On 20 mesh ____________________ __ 14.0% max.
highly desirable on a theoretical basis. High-density com
positions providing greater weight of explosive, and thus
Through 100 mesh _______________ __
increased available energy, per unit volume make pos—
sible the use of fewer and/ or smaller diameter boreholes,
The ingredients were mixed until a uniform blend was
equivalent blasting energy being provided by a lesser
volume of high-density explosive. The savings in drilling
apparent and then the free-running mixture was dis
charged from the mixer. A 4-inch-diameter, 24-inch-long
metal can of the type conventionally used for explosives
costs resulting from reduction in number and size of the
boreholes are of obvious importance. However, in prac
was packed with the formulation in the amount of about
6725 parts. The density of the material within the can
was 1.43 grams per cubic centimeter. ‘The explosive cart~
ridge was submerged in water and was initiated by a
tice, these theoretical considerations are complicated by
several factors.
In the main, the relatively high costs of the available
high~density explosives, e.g. blasting gelatin, more than
standard 4-pound pentolite ‘(TNT-PETN) primer. The
counteract the economies effected by reduction in drilling
charge detonated at a velocity of 3135 meters per sec~
costs. This factor, and also the undesirably high initi
Example 2
ation sensitivity of blasting gelatin and the like, has led
to widespread usage in blasting operations of the lower
A formulation comprising 36% by weight of the TNT
cost but low-density ammonium nitrate-type composi
pellets, 54% by weight of the sodium nitrate, and 10%
by weight of ferrosilicon was prepared and packaged in
To overcome the aforementioned de?ciencies of the
accordance with the procedures of Example 1. The free
high-density explosives, certain cast explosives which are
running explosive, which was present in the metal con
of high density, low cost, and satisfactory sensitivity have
tainer in the amount of 6880 parts, had a density, as
been developed for use in blasting operations. These
packed, of 1.46 grams per cubic centimeter. Upon initi
cast compositions, in spite of their many advantages, are
ation under water by the pentolite primer, the charge
at times de?cient in that their rigid nature prevents their
detonated at a velocity of 3580 meters per second.
expansion to ?ll the borehole volume, which naturally as
reduces the advantages resulting from their high density.
This problem is also encountered to some extent with the
high-density blasting gelatins which must be tamped to
?ll the borehole space. Really e?icient tamping is seldom
achieved, especially in those boreholes formed by the 4
“jetting” technique and thus having very irregular con
tours. Inasmuch as the “jetting” method of drilling is
becoming more and more prevalent, the tamping pro
cedure, on a whole, is becoming less and less popular.
Accordingly, an object of the present invention is the ,
provision of an improved blasting composition. Another
object of the present invention is the provision of a blast
ing explosive which is of high density but low cost. A
further object of the present invention is the provision of
such a blasting composition which is free ?owing in .
nature and can be readily poured to ?ll the entire volume
of the borehole.
i have found that the foregoing objects may be achieved
when I provide a blasting composition comprising sodium
nitrate admixed with high-density, essentially spherical
trinitrotoluene (TNT) pellets relatively uniform in size.
Example 3
Another mixing was prepared and packaged by the
Example 1 procedures, the composition comprising a
free-running mixture of 38% of the TNT pellets, 60%
of the sodium nitrate, and 2.0% of motor oil. The
?lled metal container held 6330 parts of the formulation
which had a density, as packed, of 1.36 gram per cubic
centimeter. The charge was initiated under water by
the pentolite primer and detonated at a velocity of 3970
meters per second.
Two other formulations were prepared, in one of which
grained TNT was substituted for the pellets and in the
other the TNT pellets were replaced by ?aked TNT.
Formulation A consisted of 38.5% of grained TNT, 60%
of the sodium nitrate, and 1.5% of a low-viscosity mineral
oil (commercially available as “Bayol” F), Formulation
B being identical with the exception that the TNT was
?aked. The 4 x 24 inch metal container held only 5780
parts of Formulation A (density, 1.22 g./cc.) and only
.60 6020 parts of Formulation B (density, 1.27 g./cc.). When
initiated by the pentolite primer, Formulations A and B
In accordance with the present invention, a metallic fuel,
detonated at velocities of 4100‘ and 3100 meters per sec
which influences density and detonation velocity, and/or
ond, respectively.
a hydrocarbon oil, which assists in maintaining the proper
Example 4
intermingling of ingredients, optionally may be included (55
A number of other free-running mixings were prepared
in the formulation.
and packaged as aforedescribed, the compositions and
The following examples serve to illustrate speci?c em
the properties of the mixings being summarized in the
bodiments and features of the present invention. How
following table. In all cases, the mixes were initiated
ever, they will be understood to be illustrative only and
not as limiting the invention in any manner.
Parts in
under water by 4-pound pentolite primers.
Ingredients (wt. percent)
Mix N0.
Metal Fuel
F oil
Wt. of
in cartridge
D. of
Velocity of
Compn. Detonation
6, 750
6, 650
6, 800
6, 560
7, 610
1. 42
1. 40
1, 515
3. 300
1. 44
1. 39
3, 100
3, 210
1 Prilled sodium nitrate (coarse granules).
As has been exempli?ed, free-running explosive com
positions of high-density and desirable sensitivity may be
readily prepared by simple mechanical admixture of TNT
pellets with sodium nitrate and optional modi?ers. Al
though the other ingredients naturally exert an in?uence
In addition to the exempli?ed ferrosilicon, aluminum, and
iron, suitable metallic fuels include all those convention
ally incorporated into blasting compositions, for example,
manganese, magnesium, ferromanganese, and magnesium
silicon alloys, among others.
The hydrocarbon oil, for example mineral oil or motor
oil, may be incorporated, if desired, in slight amounts, e.g.
upon density, it may be seen from Example 3 that all
other things being equal, the use of pelletized TNT results
in greater density than does the employment of either
grained or ?aked TNT.
up to 2%, as an “antisegregating agent,” that is to main
To facilitate the attainment of
tain the proper intermingling of ingredients.
Due to its free-running nature, the present explosive
composition may be employed in a number of ways in
blasting operations. It may be packaged in conventional
high density, the TNT pellets should be of high density.
To expedite the formation of a uniform mixture, the TNT
pellets should be substantially spherical in form and rela
tively uniform in size, that is, their diameter should fall
shells, say of paper, or in the Waterproof metal cans
commonly used, the exempli?ed formulations being pack
within the limits of narrow range. Thus, the use of TNT
pellets meeting the afore-mentioned prerequisites consti
aged in the latter manner to facilitate testing. Advan
tutes a critical feature of the present invention. Suitable 30 tageously, the composition may be poured directly into
TNT pellets are readily available commercially as “pel
letol” pelleted TNT. These pelletol pellets are free-flow
ing and water-resistant. The diameter of the individual
pellets is 1/16—3/16 inch. Their absolute density is 1.55
1.60 grams per cubic centimeter, while their bulk density 35
dry boreholes to give an explosive column conforming to
the borehole contours. “Wet holes” may be provided
with a liner of plastic, e.g. polyethylene, which prevents
contact of the composition with water and permits the
falls within the range of O.90—1.05 grams per cubic centi
loading of the composition in loose form into “wet holes.”
Of course, if the hygroscopic sodium nitrate is provided
meter. Although these exempli?ed pellets function very
with a protective waterproof coating, the composition
satisfactorily and, thus, their use constitutes a preferred
may be used in “wet holes” without the employment of
embodiment of the present invention, other TNT pellets
auxiliary waterproo?ng means, e.g. the plastic borehole
meeting the afore-mentioned requirements may be sub 40 liner or metal or other Waterproof shells, because the other
stituted, when available, for the exempli?ed material.
components of the formulation are not seriously affected
The TNT pellets are incorporated in the mixture in the
by water.
amount of at least 25% by weight, in order to insure
The invention has been described in detail in the fore
propagation of the detonation. The most important fac
going. However, it Will be apparent to those skilled in
tor determining the upper limit on the proportion of TNT 45 the art that many variations are possible Without departure
used is an economic factor, the cost of the ?nished com
from the scope of the invention. I intend, therefore, to
position being directly proportional, on the whole, to the
be limited only by the following claims.
amount of TNT present. Inasmuch as increases in the
I claim:
TNT content beyond 40% increase the total cost of the
1. A substantially dry high-density, free-running ex
composition without effecting material gains in its per
plosive composition which consists essentially of a hetero
formance, I prefer to employ not more than 40% of TNT
geneous mixture of 25-40% by weight of high-density
pellets in the composition.
To obtain the desired high density, the TNT pellets
TNT pellets relatively uniform in size and substantially
spherical in form admixed with 48—64% by weight of
must be mixed with sodium nitrate as the oxidant, other
sodium nitrate, 0-20% by Weight of a metallic fuel se
being of too low absolute density to serve the purposes
of the present invention. The sodium nitrate is used in
the amount of 48—64%. Its granulation per se is not
num, and iron, and 0—2% by weight of a hydrocarbon
oil selected from the group consisting of motor oil and
mineral oil, said explosive composition having a bulk
conventional oxidants, for example ammonium nitrate, 55 lected from the group consisting of ferrosilicon, alumi
critical, although naturally the ?ner igranula-tions give
density of at least about 1.4 grams per cubic centimeter.
higher packed densities than those resulting from the em 60
2. An explosive composition according to claim 7,
ployment of very coarse sodium nitrate, for example prills.
wherein said TNT pellets have a diameter within the
As illustrated in the foregoing examples, the novel
range of JAGJAG inch, a bulk density of 0.90-1.05 grams
blasting agent compositions of the present invention are
per cubic centimeter, and an absolute density of 1.55-1.60
characterized by a bulk density of at least about 1.4
grams per cubic centimeter.
grams per cubic centimeter.
A metallic fuel optionally may be included in the formu
References (Jilted in the ?le of this patent
lation in an amount of up to about 20% by Weight. The
inclusion of such fuel naturally modi?es density, oxygen
balance, and velocity of detonation, and, thus, these fac
tors must be considered in the selection of the speci?c
metallic fuel and its percentage. The metallic fuel natu
rally should be employed in ?nely divided state to pro
vide an essentially uniform commingling of ingredients.
Snelling et al. ________ __ 'Feb. 14, 1928
Winning ____________ __ Jan. 31, 1956
Cook et al. __________ __ Mar. 29, 1960
Great Britain ________ __ Aug. 22, 1956
Patent No. 3,026u22l
March 2OI 1962..
William E. Kirst
It is hereby certified that error appears in the above numbered pat
ent requiring correction and that the said Letters Patent should read as
corrected below.
Column 4, line 60‘, for the claim reference numeral "7"
Signed and sealed this 24th day of July 1962.
Ams?ng Officer
Commissioner of Patents
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