US1453976A - Composition for detonators - Google Patents

Description

a aw ri l-lei} 1, 155a,

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eminar enema, or TAMAQUA, PENNSYLVANIA, ASSIGNOB T ATLAS POWDER or WILMINGTON, DELAWARE, A cesarean-HON or DELAWARE.

COYMPOSITION FOR DETONATORS.

of? uv zom irwm-g/ concern: B it known that BENNETT Gno'r'rx, citizen the United States, residing at Tamaqua, lLt county of Schuylkill and State of EKnnsylv-ania, has invented certain new and useful Improvements in Compositions for Detonators, of which the following is a a ciiication.

This invention relates to .a blasting cap compo; tion and this application is a continuation in part of my application Serial 1 amber 517.661, filed November 25, 1921 Patent X0. 1,-l39,099 of December 19, 1922.

The application above referred tixcovers broadly the use of mercurous azide and fulurinate of mercury as a blasting cap or detonator composition and also covers the use of these ingredients in combination with an oxidizing: agent. such as potassium chlorate and further covers the use of the foregoing in combination with a suitable secondary charge, such as T. N. T.

The present continuing application is ely related to the foregoing and is inl d to cover:

Certain specific proportions of the tlients found upon extensive investigaive highly efiicientresults in an cal way; and so (a) ifertain claims originally presented in the above named parent application and cancelled therefrom under the requirement of division and which claims relate to a spe- "ie type of secondary charge.

J. Patents 904,289 of November 17. iQOS'and 1.128.39l of February 16, 1915 i) th issued to L. ohler, disclose the use an aside in a detonating' compound but the particular metal disclosed by the aforesaid patents is lead azide and not mercurous .-azide as set forth herein. There are certain technical reasons why niercurous azide is much more etiicient for use in the connection stated than lead azide, particularly when the metal azide is to be mixed with fulminate of mercury. Among these reasons may be mentioned the following:

Different metals or alloys which are suitable for detonator casings or shells in most cases react oppositely with fulminate of mercur and lead azide so that as a rule a shell material which is satisfactory for one compound is highly unsatisfactory for the other. Forinstance.fulminateofinercurycan be used in copper shells. but cannot be used all) Serial .No. 594,979.

shells because. in contact with copper, le'ad' azide forms a dangerously sensitive copper azide. Thus it is evident that a mixture of these two compounds cannot be used in shells made of certain non-sparking metals, such as copper and aluminum, because the metal which would be suitable for the one compound would be attacked by the other.

The above explanation is fully confirmed by experiments and b the fact that there is now bem markete a tetryl detonator, primed Wltl'l lead azide, which, in turn, is covered with a third charge of an easily ignitlble substance, other than fulminate of mercury, all of which is contained in an aluminum shell. Therefore, it would appear that all hope of utilizing a mere mixture of fulminate and an azide has been abandoned. The foregoing difiiculties do v not exist with respect to the mercurous salt of hydrazoic acid employed by me which salt may be mixed with fulminate of mercury, with or without the addition of potassium chlorate and charged into ordinary detonator shells without deterioration of the latter.

Although the mercury salts of hydrazoic acid have been considered too dangerous to have practical importance I have found that the mercurous compound, in contradistinction to the mercuric azide, can be made by methods which will produce a comparatively safe product. Mercurous azide is admirably suited for admixture with mercury fulminate because, in the first place, both compounds being salts of the same metal may be mixed without danger of chemical action, and in the second place, there is no appreciable action between such a mixture and shells which would be suitable for fulminate detonators. Throughout extensive experimentation-I have found that the mercurous compound, in contradistinction to lead azide, does not form the super sensitive copper azide. Even in a moist atmosphere of carbon dioxide, copper is not appreciably attacked by mercurous azide, while, under similar conditions, lead azide very rapidly gives rise to the dangerous copper compound. The secret of this chemi- 4 cal inactivity of mercurous azide has two possible exp nations, either of which may e de endent on the other.

1. he comparative positions of the metals involved, in the electro-motive series.

2. The comparative solubilities of mercurous azide and'lead azide in water.

It is a. well known fact that the mutual reactivity of different salts and metals is largely dependent on the positions of the metals involved in the e-lectro-motive series, with respect to hydrogen. In general the wider the gap between two metals. the more rapid will be the reaction. The following table of specific electrode potentials indicates a positive potential value for both. aluminum and lead and negative values for copper and mercury. This is in accord with the fact that mixtures of lead azide and fulminate of mercury cannot be used in either copper or aluminum shells.

Electrode Metals. potentials. Aluminum +1.0-l0* Lead +0.12" Copper -O.51 Mercury -0.80

"Neumann, Zeitshrift fur Physik, chemie, 14, 229.

Noyes and Sherrill, Principles of Chemistry, p. 164.

tent of 0.03 grams per liter. while leadazide.

under the same conditions. is soluble to the extent of 0.38 grams per liter. A small amount of water is almost unavoidably present in a detonator charge, remaining from a previously wet condition of the ingredients. or from being supplied from the moisture in the air, or both. The fact that lead'azide is more than twelve times as soluble as mercurous azide is also in accord with the much greater tendency of lead azide to have its metal displaced by certain other metals, such as copper.

Theaction of carbonic acid must also be considered. Carbon dioxide is present in the atmosphere. In combination with water it forms carbonic acid, which may act upon the azide with the liberation of the highly volatile hydrazoic' acid, which in turn may act upon the copper of the shell, with the formation of the dangerous copper azirl e. The above figures show that mercurous azide is almost insoluble. Thorough and exhaustive tests in an atmosphersof carbon dioxide and moisture have shown that copper or gild'ing metals shells with mercurous azide do not fOlll'l this dangerous compound. in a detectable amount, even over a long period of time. Lead aside, on the other hand, under the same comparative cond'i tions quickly forms a deposit or? this supersensitive ccn'ipound.

Further, under the influences moisture and carbon dioxide, lead aside may converted to, a non-explosive mess, while, an der the same conditions, mercurous azideie not noticeably affected. it is well known that ordinary air contains moisture and carbon dioxide and that mine air often con-- tains even greater amounts.

In addition to bein r wholly practical from a standpoint of sta ility, 1 have found that from a standpoint of detonating efdciency, the admixtures of small quantities of mercurous azide'with fulminate of mercury, produces most gratif ing results. By extensive experimentation 'have also found that the advantageous ell'ects of such mixtures hold equally true when the, mixtures include suitable proportions of potassium chlorate. The addition of potassium chlorate to the primary detonating composition in'detonators is a well known and common procedure. These advantages may be summarized as follows:

1. The brisance or detonating value is greatly increased. The inner capsule, which is essential in a mercury fulminate-tetryl detonator, may be dispensed with, and a smaller priming charge used effectively.

2. Such mixtures are practically unaffected by moisture, whereas mercury fulminate or mercury fulmina-te-potassium chlorate alone are easily "and quickly made ineffective by moisture.

3. Detonators charged with such mixtures are unimpaired by pressures at which 't'ulminate' of mercury or fulminate of mercury potassium chlorate mixtures become dead pressed.

. 4. Such mixtures retain the same prop- 'erty of ease of ignition as does straight mercury fulminate, the flash point of various' mixtures being practically identical with that of fnlminate of mercury.

The proportions employed in the charging of a blasting ca are as follows: A. base charge consisting o 0.4 of a gram or" tetryl and a 0.4 gram priming charge, made up of 60% fulminate of n'iercury, 20% mercurous azide and 20% chlorate of potassium.

\Vhile I prefer to employ tetryl as the base charge the invention is not necessarily limited thereto, since theproportions recited for the priming charge are of importance and advantageous in connection with various kinds of base or secondary charges among which may be mentioned tetranitroaniline, intro-starch, hexanitrodiphenylamine, T. N. T. or cyclotrimethylenetrinitramine.

Having described my invention What I claim is 4. A detonator charge comprising a base charge of tetryl and a riming charge made up of 60% of fuhninate of niernury, 20% mercurous :izide and 20% chioraee of potassium. v

5. A detonator charge comnrising base charge of 0.4 gram of tetryi'and a 0.4: gram priming charge made up of 60% fnhnmwte of mercury, 230% mercnrous oxide and. 20% chlorate of potassium.

In testimony whereof he nfiixes his signal ture in the presence of two witnesses,

BENL IETT GRUT'EQA. 'Witnesses:

R. L. HILL, H. N. FINN.