Improved Manufacture of Explosives
Year: 1896

page_text: Improved Manufacture of Explosives.
GEORGE BENEKÉ, of 13 Hesketh Street, Southport in the County of Lancashire,
Gentleman, do hereby declare the nature of this invention to be as follows:-
This invention relates to an improved manufacture of explosives from nitrate of
ammonia or other inorganic nitrates and resins or resinous bodies.
When making explosives of this description, which, on account of the difficulty
of their ignition and comparative safety in mines, are generally known as "safety
explosives" great attention has to be paid to the molecular aggregation of the
constituent particles. By some it is regarded essential that the resinous constituent
completely envelopes the particles of nitrate of ammonia in order to prevent its
partial volatilisation or absorption of moisture from the atmosphere. Others
again consider it essential to rapid ignition and consequently powerful explosive
action that the particles of ammonium nitrate be not completely surrounded by
resin, but merely rendered adhesive, and various mechanical devices have been
patented for securing the complete or partial envelopment of the nitrate particles
by the resin.
Nevertheless even when manufactured under the conditions said to secure only
the partial envelopment of the nitrate particles and the rapid transmission of
ignition, the explosive compound when detonated is frequently only partly
decomposed, and the residue contains lumps of unexploded mixture which not only
prevent the full explosive force being generated, but are also a source of danger.
According to my present invention what I first aim at is the intimate admixture
of the ammonium nitrate and resin or other ingredients in suitable proportions, to
which is added a small proportion of bichromate of potassium, sodium, or ammonium,
or other similar oxidising agent, but preferably bichromate of potassium. The
addition of the bichromate I have discovered not only effects the more complete
detonation of the nitrate of ammonia than has hitherto been attained, but also
increases the safety of the explosive when fired into mixtures of coal-dust and
pit-gas.
It is essential that the mixture of the ingredients shall be of the most even and
intimate character, and I prefer to mix them in the following manner and in the
following proportions as giving an explosive of great strength & safety, although
it may be necessary or advisable to modify both the method and the proportions
according to the nature of the ingredients used and the qualities required in the
explosive. Also if I require a weaker explosive I may substitute nitrate of soda
or potash for nitrate of ammonium.
I dry 92 parts of nitrate of ammonia at a temperature of 100° C. for two hours
and grind it to an extremely fine powder. Then I add 5 parts of resin previously
finely ground, (or I may grind the ammonium nitrate and resin together) and
2 parts finely ground bichromate of potassium. This mixture I place in a
revolving drum which contains a fan or spiral screw shaft revolving in the opposite
direction to the drum, and cause the mixture to be rotated for four hours or more
until uniformly mixed.
I then place the mixture on a stout melting pan heated with a jacket of steam
to a temperature of about 100° C., and for fifteen minutes the mixture is constantly

page_text: stirred, raked and crushed or rolled at this temperature by mechanical means, so
constructed that the heating pan revolves one way and the mechanical stirring,
raking and crushing or rolling gear works in the opposite direction, as in a
mortar mill.
After fifteen minutes steam is cut off from the jacket and the mixture is allowed
to cool, but the pan and other gear is kept in rotation for an hour or so until the
mixture is fairly cooled. It may then be packed or made up into cartridges.
Dated this 23rd day of June 1896.
I, GEORGE BENEKÉ of 13, Hesketh Street, Southport in the County of
Lancashire, Gentleman, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
This invention relates to an improved manufacture of explosives from nitrate of
ammonia or other inorganic nitrates and resins or resinous bodies, for the better
detonation of which bichromate of potassium or other oxidising body is added.
When making explosives of this description which, on account of the difficulty
of their ignition and comparative safety in mines, are generally known as "safety
explosives," great attention has to be paid to the molecular aggregation of the
constituent particles. By some it is regarded essential that the resinous constituent
completely envelopes the particles of nitrate of ammonia in order to prevent its
partial volatisation or absorption of moisture from the atmosphere. Others again
consider it essential to rapid ignition and consequently powerful explosive action
that the particles of ammonium nitrate be not completely surrounded by the resin
but merely rendered adhesive, and various mechanical devices have been patented
for securing the complete or partial envelopment of the nitrate particles by the
resin.
Nevertheless even when manufactured under the conditions said to secure only
the partial envelopment of the nitrate particles and the rapid transmission of
ignition, the explosive compound when detonated is frequently only partly decom-
posed, and the residue contains lumps of unexploded mixture which not only
prevent the full explosive force being generated, but are also a source of danger.
According to my present invention what I first aim at is the intimate admixture
of the ammonium nitrate and resin or other ingredients in suitable proportions,
to which is added a small proportion of bichromate of potassium, sodium, or
ammonium, or other similar oxidising agent but preferably bichromate of
potassium.
The addition of the bichromate, I have discovered not only affects the more
complete detonation of the nitrate of ammonia than has hitherto been attained,
but also increases the safety of the explosive when fired into mixtures of coal dust
and pit gas, provided that the resins or resinous bodies mixed therewith, after being
heated, remain of the most even and intimate character and that the nitrate of
ammonium is free from moisture.
In previous inventions for the manufacture of explosives from ammonium nitrate
and resin, it has been specifically enjoined to heat the resin either until it begins to
melt or until it is wholly or partly melted, before mixing with the other ingredients,
in order to obtain the proper state of aggregation of the constituent particles.
This method of mixing is however very faulty, because the resinous particles

page_text: cobere and prevent the uniform mixture of the ingredients which is essential to the
production of a good and safe explosive. By my method of mixing hereafter
described new and better effects are produced.
It is essential that the mixture of the ingredients shall be of the most even and
intimate character, and I prefer to mix them in the following manner and in the
following proportions, as giving an explosive of safety and great strength equal to
about the strength of dynamite, although it may be necessary or advisable to-
modify the proportions according to the nature of the ingredients used and the
qualities required in the explosive. Also if I require a weaker explosive, I may-
substitute nitrate of soda or potash for nitrate of ammonium.
I dry 92 parts of nitrate of ammonia at a temperature of 100° C. for two hours.
and grind it to an extremely fine powder and whilst still hot I add five parts of
resin previously finely ground, which must be in a cool or dry state (or 1 may grind
the ammonium nitrate and resin together), and 2 parts finely ground bichromate
of potassium.
This mixture I place in a revolving drum which contains a fan or spiral screw-
shaft revolving in the opposite direction to the drum and cause the mixture to be
rotated for four hours or more until uniformly mixed.
In order to drive off any traces of moisture, which would deteriorate the explosive
and tend to increase the temperature of the explosion, I then place the mixture on
a stout heating pan heated with a jacket of steam to a temperature of about
75 to 100° C., and for fifteen minutes the mixture is constantly stirred, raked and
crushed or rolled at this temperature by mechanical means, so constructed that the
heating pan revolves one way and the mechanical stirring, raking and crushing
or rolling gear works in the opposite direction, as in a mortar mill.
After fifteen minutes steam is cut off from the jacket and the mixture is allowed
to cool, but the pan and other gear is kept in rotation for an hour or so until the
mixture is fairly cooled.
This treatment will abstract any small amount of moisture which the mixture
may still contain and it will keep the mixture of the ingredients in the most even
and intimate condition and prevent the caking together of finely ground resin..
The product is a good, reliable, most powerful and safe explosive which will readily
detonate. For its preservation it must be hermetically packed or made up into
waterproof cartridges.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:
1. The herein described manufacture of an explosive, cousisting of a pulverised
mixture of ammonium nitrate, resin, and chromate or bichromate, preferably-
bichromate of potassium, the mixture being made under the conditions above set.
forth.
II. An explosive manufactured as above set forth.