US1488787A - Explosive and process for its manufacture - Google Patents

Description

Patented Ag. 1, 1924.

UNITED: STATES PATENT OFFICE.

ll'o Drawing.

To all whom it may concern:

Be it known that I, ETIENNE HAnmi, residing at 1 Rue dHarcourt, Rouen, Seine-Inferieure, France, have invented certain new and useful Improvements in Explosives and Processes for Their Manufacture, of which the following is a specification.

It is known that mixing mercury fulminate with fatty matters (oils, greases, paraflins, etc.,) renders the mercury fulminate less sensitive to shock. Thus the detonating fuse employed by the Austrian army comprises a core or mercury fulminate containing a high proportion of paraffin.

When however as is usual the mercury fulminate is mixed with high (proportion of fatty matters, it is insensitize to such a degree that a detonator of pure fulminate is re uired to detonate it.

he fuhninate if it is to preserve its priming action can only be mixed with a much smaller quantiy of fatty matters. Hitherto the proportion of fatty matters mixed with the fulminate has been far lar er than is sufiicient to render it insensitive owing to which insensitized fulminate detonators have been used to the best advantage.

It has now been discovered that mercury fulminate is insensitized with a far smaller quantity of fatty matters than has hitherto been employed. Thus detonators charged in the ordinary manner with 1.2 grams of trinitrotoluene or with picric acid or with tetryl may leave a very large quantity of unexploded material if detonated with 0.42 gram mercury fulminate containing even 0.05% of its weight in oil. Butif the fulminate is not mixed with oil such quantity of fulminate is sufficient in all cases to cause complete detonation and this quantity of pure fulminate has usually been employed in ractice. v

ccording to this invention an insensitized explosive still retaining its full priming power is produced by mixing lead azide with a much larger quantity of fatt matters (oils, greases, parafiins, etc.). T e quan- Application filed March 27, 1923. Serial No. 628,078.

tity of fatty matters which it is possible to incorporate with it would with certainty render mercury fulminate insensitive: the quantity added may exceed 300 times that which suflices to insensitized mercury fulminate. Thus lead azide may be mixed with up to 14% of its weight of oils, greases or parafiins without its priming properties being substantially modified and without it being necessary to employ a quantity of fatty azlde greater than the weight of pure normal fulminate to cause complete detonation. v

Detonators' charged with 1.2 grams of trinitrotoluene and primed with 0.33 gram only of lead azide. and containing 12% par aflin never fail. l

The quantity of fatty azide to be added varies with. the proportion of fatty matters incorporated. The table set out below by way of illustration shows the quantities of fatty azide that experiment has shown to be necessary practically to obtain the same effect as with the detonators charged with 0.42 gram of pure fulminate:

0.33 gram. fatty azide containing 12% paraflin. I

0.65 gramv fatty azide containing 15% parafiin.

0.90 gram fatty azide containing 20% parafiin.

These compoun detonator whose lower charge is trimtrotoluene (T. N. T.). If tetryl (Eng lish and German detonators) which is much more sensitivebe employed in a compound charge, the quantities ofazide may evidently be smaller. Thus detonators charged with tetryl require in practice only a single charge of 0.15 gram azide admixed with 12% of paraffin provided a top cap is employed.

' As will be seen, the quantity of azide varies with the quantity of paraflin added and with the sensitiveness of the mixed charge. But with fulminate containing a like proportion of fatty matters there will always bemisfires.

Parafiin for example may be admixed guantities of azide correspond to a a in a very simple manner either directly and with heat or y emplo ing a known solvent of paraffin which is then evaporated.

Lead azide insensitized by means of parafiin allows fatted lead azide to be obtained in the form of, small grains. The small grains are obtained in any suitable manner,

or example by those which have been employed for granulating black powder. The advanta es obtained by the employment of such hig proportion of fatty matters and which form the object of the present inventionare:

1. An easier and less dangerous manipulation of the azide, dust is completely prevented by this coating.

2. The introduction of large quantities of solid parafiin or other grease a lows explosive grains of the size desired easily to be obtained by the use of sieves. If charging hoppers now in use are employed very regular charges of the substance can be obtained.

3. The azide so coated is, if the quantity of fatty bodies be sufficient, quite insensitive to the action of water.

Detonators whose layer of azide contains 10 to 12% of parafiin may be filled with water without in any way losing their explosive properties after the water they contain has been poured off. The layer of fatty azide, being unwettable and impermeable to water, protects the layer of comressed trinitrotoluene or of tetryl below it at the bottom of the detonator from the action of the water.

4. As water has no action on detonators.

thus constituted, vthe carbonic acid of the atmosphere has also no action and one of the main defects in the use of lead azide is that it is attacked by carbonic acid which is often encountered in certain mines; to this cause several inexplicable accidents have been attributed which occurred when detonators containing lead azide were first used. Detonators whose lead azide contains a high proportion of paraiiin for example, are thus very efiectively protected agalnst the action of carbonic acid and the humidity of the atmosphere.

5. Coating the azide with a fatty body "also has'for effect that the nitride has no action upon metals. It is known that so far as possible azide should be charged in tubes other than the usual copper tubes; special precautions at least should be taken. It is known that the carbonic acid of the atmosdangerous. Similar reactions need not be Lesa-re? feared with the lead azide coated with a fatty bodyas above described.

6. The introduction of these hi h proportions of paraffin for example (W ich in no way diminishes the priming properities of the single azide) allows other bodies to be mixed with it such as-those employed in the manufacture of percussion caps for sporting or war cartridges. The mixture which is intimately bound by the paraffin, remains homogeneous whatever may be the shock or manipulations to which it may be subjected.

7. Finally the high proportions of fatty matters which may also be introduced into lead azide without practically weakening its priming properties renders it more easily manipulable by diminishing its sensitiveness to shock. Azide containing 14% of paraflin is infinitely less sensitive to shock than mercury fulminate.

Claims:

1. Process for obtaining a desensitized priming body which retains its primin properties which consists in mixing lea azide with a proportion of fatty matters greater than the minimum proportion which added to mercury fulminate would so inscnsitize the fulminate as so to reduce its priming power that it would cause misfires.

2. Process for obtaining a desensitized priming body which retains its priming properties, which consists in incorporatin with lead azide by mixture, a proportion 0% fatty matters greater than 0.05% and less than 20%.

3. Process for obtaining a desensitized priming body which retains its priming properties, which consists in incorporating with lead azide a proportion of about 14% of fatty matters.

4. Process for obtaining a desensitized priming body which retains its priming properties and is suitable for being easily charged into detonators, which consists in incorporating with lead azide a proportion of. solid fatty matters suflicient to granulate. the mass obtained.-

5. Process for obtaining a. desensitized priming body which retains its priming properties and is suitable for being easily charged into detonators, which consists in incorporating with lead azide a proportion of about 14% of paraifin and in granulating the mass obtained. r

6. A desensitized priming substance possessing a priming power substantially similar to that oflead azide, which contains a mixture of lead azide and fatty matters in the proportion of 0.05% to 20% with respect to the lead azide.

7. A desensitizedpriming substance possessing primingpower practically similar to that of lead azide, which contains a mixture of lead azide and fatty matters in a proportion of about 14% with respect to 9. A (letonator having as priming subthe lead azide. stance lead azicle with which is incorporated 8. A desensitized priming substance posone or more fatty matters in the proportion 10 sessing priming power practically similar of 0.05-to 20%. i 5 to that of lead azide which contains amix- In testimon whereof I aflix my signature.

ture of lead azlde and about 12 to 14% of para-fiin. ETIENNE HARLE.