[0001] This invention concerns explosive charges obtained by the cold-mixing of oxidizing
salts with liquid nitro compounds.
[0002] Nitro compounds here mean those organic compounds (called nitric esters) in which
the N02 groups are bonded directly to atoms of C and not through an atom of 0.
[0003] The invention also concerns procedures to obtain such explosive charges.
[0004] To be more exact, the invention concerns the production of explosive charges by using
at least ternary mixtures of aromatic nitro compounds, the composition of the latter
being such that they are normally liquid at the ambient temperature, so that mixing
with nitrates can be carried out at the ambient temperature.
[0005] The aromatic nitro compounds employed in the art of explosives are many in number:
nitrobenzenes, nitrotoluenes, nitrophenols, nitronaphthalenes with one, two, three
or more nitric N02 groups in the molecule, but for various practical reasons only
the nitro derivatives of toluene, in particular trinitrotoluene and dinitrotoluene,
remain in use now.
[0006] The mixing of these compounds with nitrates (mainly ammonium nitrate) is normally
carried out with two procedures:
1) hot-mixing with the use of melted nitro compounds;
2) cold-mixing (at about the ambient temperature) with the use of powdered nitro compounds.
[0007] The known procedure with hot-mixing has a considerable requirement of energy to heat
the components and reduces the productivity of plants owing to the long heating and
cooling times. Moreover, this procedure entails difficulties in correct processing
to avoid a decline in the quality of the product.
[0008] Such a decline in quality is due to hardening of the explosive mixture at temperatures
close to that of crystalline conversion of the ammonium nitrate or at temperatures
of solidification of nitro compounds including dinitrotoluene too.
[0009] The known procedure with cold-mixing provides a low quality product which has low
sensitivity and less explosive power.
[0010] Some patents which disclose explosive charges are known and include:-CA 1,382,222:
this patent claims a liquid composition to be used to fracture underground rocks near
well drillings, the composition being based on a nitric ether such as diethylene glycol
dinitrate; this liquid can contain substances which vary the freezing temperature,
viscosity, stability, sensitivity, etc.
[0011] Nitro components are not used in this composition and this patent is therefore outside
the field of application of the present invention.
[0012] US 1,820,567: this patent discloses explosives based on chlorates alone, which therefore
do not form part of the field of application of the present invention.
[0013] US 1,820,568: this patent discloses explosives consisting of an absorbent in coal
powder, various chlorates and a mixture of liquid nitro compounds. This mixture contains
two nitro . compounds and is liquefied by heating before it is mixed with the other
components. This composition also discloses other substances outside the field of
the present invention.
[0014] US 1,968,158: this patent discloses the production of a very homogeneous explosive
mixture to be used molten or cast and based on ammonium nitrate and nitrates of aliphatic
amines. This patent is outside the field of application of the present invention as
regards both its method of use and its composition.
[0015] US 3,178,325: this patent discloses explosives based on sodium, calcium, barium,
strontium and potassium nitrates in association with sensitizers such as aromatic
hydrocarbons. It does not deal with nitro compounds and is therefore outside the field
of the present invention.
[0016] DT 1.646.307: this patent discloses explosive mixtures which are solid at 70°C and
are based on tetryl or ethyl tetryl mixed with hexogen,·octogen or pentaerythrite;
stabilizers and polymers such as resins or nitrocellulose may also be used. However,
this composition does not include any of the components employed in the present invention.
[0017] Powder-type explosive charges are manufactured by mixing nitrates (mainly ammonium
nitrate, but to a lesser extent potassium, sodium or calcium nitrate) with combustible
and sensitizing substances which react by using the excess oxygen made available by
the nitrates as the supporter of combustion. Among combustible substances the ones
which have been used for the longest time are the aromatic nitro compounds, which
enable products to be made which give the best average balance as between efficiency
and sensitivity.In fact the classic product nitroglycerine and like compounds (nitric
esters)behave very little like combustible substances in a strict sense, since they
themselves contain all or almost all the oxygen needed for the reactions and thus
do not use the oxygen made available by the nitrates; on the other hand they have
great sensitivity to outside actions and therefore cannot be said to be ideal from
the point of view of safety; whereas mineral oil, which is used a great deal nowadays
in mixtures with ammonium nitrate, exploits very fully the oxidizing properties of
that salt but does not always enable sensitive enough products to be obtained, particularly
when the explosive charges are only slightly stemmed or have a small diameter.
[0018] Aromatic nitro compounds provide a compromise solution which offers the best obtainable
from the various foregoing points of view. They have a satisfactory behaviour as combustible
substances, enough but not excessive sensitivity after mixing and very good long term
stability together with a low vapour pressure, which enables losses by evaporation,
such as those experienced with Diesel oil, to be avoided.
[0019] To avoid the shortcomings of the prior art, which discloses hot-mixing and cold-mixing
procedures respectively to manufacture explosives based on inorganic nitrates and
nitro compounds, the present applicant has studied, experimented and obtained the
present invention, which also enables many benefits to be provided, as will become
clear in the description hereinafter. According to the invention mixtures of nitro
compounds that remain liquid at the ambient temperature are obtained on the basis
of the principle of eutectic mixtures.
[0020] It is known that, when two substances are miscible in the liquid state and not miscible
or only partly miscible in the solid state, the solidification temperatures of each
of the two components can be lowered. To obtain this reduction of the solidification
temperature a given quantity of one of the components is added to the other component.
This fall in the solidification temperature is greatest for a certain composition
which is called eutectic.
[0021] The invention envisages the use of at least ternary mixtures of aromatic nitrocompounds,
which have a composition such as will be liquid at the ambient temperature.
[0022] Such at least ternary mixtures can therefore have a eutectic composition or a composition
within the neighbourhood of a eutectic composition, the composition in all cases being
such that the mixtures are liquid at about the ambient temperature.
[0023] The invention is therefore embodied with explosive charges consisting mainly of inorganic
nitrates and mixtures of aromatic nitro compounds, the mixtures of nitro compounds
being at least ternary and having a composition such as to lead to melting temperatures
such that such mixtures are liquid at least at about the ambient temperature.
[0024] We shall give hereafter some non-restrictive examples of mixtures of nitro compounds
suitable for obtaining explosive charges according to the invention, with the help
of the attached figures.
Figs.1 and 2 give examples of binary mixtures, from which ternary mixtures can then
be obtained;
Fig.3 gives an example of a ternary mixture.
[0025] The graph of Fig.1 shows the progress of the solidification temperatures for a mixture
of orthonitrotoluene and paranitrotoluene in all possible proportions from 0 to 100%.
[0026] The graph of Fig.2 shows the solidification temperatures for mixtures of trinitrotoluene
2-4-6 (TNT) and dinitrotoluene 2-4 (BNT) in all possible proportions.
[0027] In both these above graphs the solidification temperature is lowest for a given composition
which is called eutectic.
[0028] The addition of a third component produces a further drop in the solidification temperature
of the mixture to which the third component is added; likewise there can be a ternary
eutectic, and Fig.3 shows this possibility with a three-dimensional graph.
[0029] In this figure, TNT indicates trinitrotoluene 2-4-6, while BNT is dinitrotoluene
2-6 and TNF is trinitrophenol.
[0030] The same effect can be obtained with a fourth component, and thus it is possible
to form a quaternary eutectic; graphic representation of this is not possible since
it would require a four-dimensional graph.
[0031] A well known and typical example of a quaternary eutectic composition is Wood's Alloy,
which solidifies at 60.5°C and is made with the following mixture:
- 50% Bismuth (solidification point 271°C): 25% Lead (327°C): 12.5% Tin (231°C): 12.5%
Cadmium (321°C).
[0032] In the invention at least ternary mixtures are used which consist of trinitrotoluenes
and dinitrotoluenes to which may be added very small quantities of nitrotoluene and
nitrobenzenes, which lower the solidification temperature even further when so required.
[0033] The following components have the solidification temperatures indicated:
trinitrotoluene 2-4-6 which solidifies at 80°C
trinitrotoluene 2-3-5 which solidifies at 104°C
dinitrotoluene 2-4 which solidifies at 70°C
dinitrotoluene 2-6 which solidifies at 65°C
orthonitrotoluene which solidifies at -3°C
metanitrotoluene which solidifies at 16°C
paranitrotoluene which solidifies at 52°C
trinitrobenzene 1-3-5 which solidifies at 122°C
nitrobenzene which solidifies at 5°C.
[0034] The mixtures obtained with the above components according to the invention have solidification
temperatures considerably lower than those of the individual components.
[0035] For instance, a mixture consisting of 60% trinitrotoluene 2-4-6, 25% trinitrotoluene
2-3-5 and 15% dinitrotoluene 2-4 has a solidification temperature of about 55°C.
[0036] A mixture consisting of 50% trinitrotoluene 2-4-6, 20% trinitrotoluene 2-3-5 and
2-4-5, 20% dinitrotoluene 2-4, 7% dinitrotoluene 2-3 and 3-5, 2% technical nitrotoluene
and 1% trinitrobenzene has a solidification temperature of about 40°C.
[0037] A mixture consisting of 35% trinitrotoluene 2-4-6, 15% trinitrotoluene 2-3-4 and
2-4-5, 35% dinitrotoluene 2-4, 10% dinitrotoluene 2-3 and 3-5, 3% technical nitrotoluene
and 2% trinitrobenzene has a solidification temperature of about 20°C.
[0038] In general it will be found' that the addition of 1% of a second, third or fourth
component to a substance already consisting of one, two or three components of the
foregoing kind lowers the solidification temperature by 0.8 to 1.2°C.
[0039] Preparation of the mixtures according to the invention is easy and fast; after the
desired quantity of ammonium nitrate or of other accessory components has been introduced
into the mixer, the liquid mixture of the nitro compounds in a desired quantity is
poured onto the powder mixture and mixing is carried on until homogenization is obtained.
The liquid penetrates into the porosity of the powdery particles and the mixing is
very intimate and homogeneous; there is no danger of the formation of hard crusts
due to solidification, for the nitro compounds are liquid at the ambient temperature
and remain such even during storage; precisely because of their liquid state they
maintain a given plasticity in the explosive so produced and obviate the formation
of annoying dust even if the working environment is very dry; this plasticity assists
the operations of packaging and also of stemming and loading the explosive charges.
1 - Explosive charges consisting mainly of inorganic nitrates and mixtures of aromatic
nitro compounds, in which the mixture of nitro compounds is at least ternary and has
a composition such as to lead to melting temperatures such that mixtures are liquid
at least at about the ambient temperature.
2 - Explosive charges as claimed in Claim 1, which contain small additional quantities
of mononitro compounds, thus obtaining a further reduction of the solidification temperature
of the mixture of aromatic nitro compounds.
3 - Explosive charges as claimed in Claim 1 or 2, which have a composition of about
that of a eutectic composition.
4 - Explosive charges as claimed in any claim hereinbefore, in which the mixture of
aromatic nitro compounds consists mainly of derivatives of toluene.
5 - Explosive charges as claimed in any claim hereinbefore, in which the mixing of
the inorganic nitrates with the liquid mixture of aromatic nitro compounds takes place
at the ambient temperature.
6 - Explosive charges as claimed in any claim hereinbefore, in which during cold-mixing
of inorganic nitrates with liquid nitro derivatives the liquid components are at least
partly absorbed by the solid components.
7 - Procedure for production of explosive charges constituted according to any claim
hereinbefore, which envisages the introduction of at least one powder-type inorganic
nitrate and of at least ternary liquid mixtures of aromatic nitro compounds within
a mixing machine for explosives at the ambient temperature according to any claim
hereinbefore and the successive mixing of the same, the mixing of the inorganic nitrate
with the mixtures of aromatic nitro compounds taking place at the ambient temperature.
8 - Procedure for production of explosive charges as claimed A in Claim 7, according
to which the mixing is carried out without the application of heat from the outside.