US2105674A - Delay action detonator and fuse and delay composition for use therein - Google Patents

Description

2405,67( i i y DELAY' Ao'rIoN DE'roNATon AND rosa AND ooMrosrrIoN Foa Usa 'riman- -DELAY 1N Y Charles Edwin Sosson, Ardrossan, Scotland, as-

signer to Imperial Chemical Industries Liniited, a corporatlonof Great Britain l Application August' 21, 193s, serial No. 93,255 InGreat BritainAugust 29, 1935 The present invention relates to the manufac-` ture of delay action detonators and fuses and lespecially to the compositions used as the delay element therein.' More particularly the invention relates to that type'of delay action detonatorv or fuseinwhich littleor no gas is given'oi in the course of the combustion of the delay composi tion and'in which the delay composition is toltally lenclosed duringv its combustion. Y

Delay action detonators and fuses of this ty not only obviate any risk ofthe explosive cartridge being prematurely ignited by contact. with iiame or hot particles ejected during the-cornbustionjof the delay composition, 'but are particularly adapted for use in fiery or dusty mines in which itis important that hot products of combustion from the delay composition should not be `allowed to come into contact with the adjacent atmosphere. f

'It has been proposed in the manufacture of electric delay action fuses of all kindswhich are totally enclosed, to employ as delay elements compositions containing. metals and oxidizingagents. Amongst the particular .compositions suggested was a mixture of equal parts of antimony and potassium permang'anate,l it being stated that in this compositionthe antimonyis completely.

, oxidized on ignition. Mixtures containing other materials have also been proposed. Some of these compositions tend to become insensitive to ignition by the fusehead on storage at raised temperatures' even' under dry conditions. and while the abovefmentioned composition consisting of antimony and potassium permanganate is satisfactory in this respect it is not veryeaslly ignited fposition.` -A further object is an ignition' coinposition of the characterdescribed which is read-- ily ignitable as prepared and maintains itsignitability on storage. A still further object is a ven' f less delayy electric blasting initiator provided with an improved substantially gasless delay ignition composition. lOther objectswill be apparent asthe invention is hereinafter more fullyde- IY havefound that these objects are accomplished byincorporating.il proportionof zinc in an ignition composition comprising antimony andy A potassium pcrmanganate. tothe pres- `m1,0 Claims (Ci. 10%710) y -ent invention'a composition for use in delay action detonators and fuses consists of a substantially gasless mixture containing antimony. zinc. and potassium permanganate. zinc is preferably between about and 25% by weight of the mixture, and the proportion of the The proportion of -l metals in the mixture is not less than that which is required to reduce the potassium permanganate in accordance with the following equations: 2sib-t'2Kt/inol=sino;|Kio+2Mno2- 3Zn+2KMnO4=3ZnO+K2O+2MnOz The presence of the zinc not only facilitates theignition of the antimony-potassium permanganate` mixtures, but also tends to increase their burning speed, and in order to compensate for this the proportion' of potassium permanganate may b reduced somewhat below' the amount which would theoretically be required according to the aboveequation's to oxidize the metals, but will not usually be less than about the-combined weights of the metals. inert material such as lead chromate or zinc oxide may be introduced into the mixture in order further to modify its burning speed.

In preparing the delay element, thecomposltion may be mled into a lead tube of somewhat greater diameter` than will vilt into place in the delay action device, and the tube may then be drawn out to reduce the-.diameter and compress the powder. The compositions of the present invention are 1 possessed of good sensitiveness to A' low percentageof an ignition, Iand when introduced intov a lead tube which is subsequently drawn to .an internal diameter of 4 mm. and placcd'inclose proximity to a fusehead such as lone ofthose described in specification No. 428,872, they ignite4 satisfactorily.-

They may also be stored at raised temperatures.

`for instanceat 50 C., without appreciable deterioration so long as they are kept quite dry, butl the compositions are liable' to deteriorate when submitted to hot'storage' in moist atmospheres.

It is therefore important ,that the detonators f fuses in which they are used should be so con- V structed that moisturecannot enter into vthem from surrounding moist atmospheres during service conditions or storage.l It is unnecessary in The construction vof a delay action detonator A to the invention is illustrated in the l accompanying which is a yerticalfmidl" section oi a detonator; ,The detonatortube l is l' l -I have illustratedtne application cfm'y lmp'rcwed ignition vcomposition to delay blasting initiators,`."

tension gasless, type of fusehead l6 with its fireprovided with a main charge 2.on to the top oi' ywhicluis pressed a drawn 'lead tube 3 containing tlie charge I4 ofthe composition containing anti-v mony, zinc and potassium permanganate. A low proof 'paper shield Eris positioned in the detomt` tor tube so that the bead 1 ofthe Iusehead is in close proximity to one end of the delayfcom? "the rubber plug 8 and a bituminous sealing comcompleting'the hermetic seal. 'I'he Alead wires 9 4pass through the plug 8 andthe. compositi'onil lowing examples.- l by weight.

siumpermanganate in the proportions 36:10-54 '(prepared from' the powdered materialsy passing illled into-a leadltube .whichvissubsequently y `A mixturefof lead chromate and parts of a mixture of antimony.. 'zinc-and potasl e 10o mesa British-standard .testing sieve) .drawn throughs die'and inserted into a deto.

Ato

more regularly andthe 'products of combustion nator'as illustrated ip 'iFigure 1. The delay period of fthe composition is approximately two seconds per centimetro.

l Example 2 i "A mixture of parts of antimony, 15 parts of zinc and55 parts 'of potassium permanganate (prepared from the powdered materials passing an 8,0` mesh (British Vstandard testingsieve') is illled -intof a leadj-'tube which is subsequently drawn through a die and inserted into a detonat'or" as illustrated vin Figure 1. The delay period of the composition is approximately two seconds per centimetre. v In the foregoing detailed descriptionv of my invention it is apparent that many variations in` detail may be m'ade without departing from the ,spirit and scope thereof. V'I'laus,A `for example, other types of electricilring means may be em'- ployed, such as the usual, type of concave plug or the like. Furthermore, other oxidizing agents may be employed in place o f potassium permanr ganate, Vfor example potassium chlorate or'perchlorate. sodium dichromate. calcium peroxide.' barium peroxide Aand the like. `Permanganatc is f preferred, however, since the composition burns "beemployed to advantage in time ring fuses of V military shells. Other variations will be'apparf `entto any one skilled `in'the art.' I intend,

therefore, to be limited only in accordance withl mate. y

ere substantially geclecc. and` finally, vtltlicugii itvisl apparent that the same composition may the following patentclaims. aI claim:

zinc, antimony, and an oxidizing'agent. Fi 1 y 1. In an electric blasting initiator a substan- Atially gesless ignition composition comprising 2; rn a delay electric biastinginltietcr a substantially gasless delay vignition composition com`, ,piisingjzinc,V antimony, and potassium,pennen` I ganate..

3. In e delay, electric blasting cap'fa substanf 'I tiitlly` gasless delay ignitionv composition compris-k ing zinc, ,-antimony, and potassiumy permanga- 4. In a delayjzelectric blasting cap a substan` tially gasless delay ignition composition .compris` ing zinc, antimony, 4I'Jotassium ,permang'anate. -andan inert material. f' l i -5. In' a fventless` delay electric blasting capga" substantially gasless delay ignitionicomposition `co`xi'i1` risingv zinc, antimony, and potassium per-.

manganate. Y 6.. In a ventless delay electric blasting cap containing 'ajdetonating base charge, ay delay 'ele.

nient zcontaining a substantially.; gasless ignition composition comprising-Zinc, antimony, and-po tassiuml permanganate, andan, electric' iiring means. f-

\ 7. In a ventless delayffy electric blastingcap substantially gasless ,delay ignition composition comprising a closed metal shell, [a ydetonating comprising 'a .closed..metal Ishell, l a` detonating'' base charge, and an :electric tiring" means,r a i ba'seoharga and an'electric ill-ing means, a'sub.

stantially gasless ,delay Vignition composition comprising zinc, antimox'mf'` potassium perman- .ganateg yand an inert materialinanamount sufll- Y. cient to modify the burning speed thereof.V -9. The ignition composition of,- claim `8, in which said inert material comprises zinc oxide.` 10. 'Ihe ignition compositionof claim 8, iny

which said inert materialcomprises leadk chro-

Images