May 23, 1939. J. TAYOR 2,159,234 GAS-PRODUCING NONDETONATING COMPOSITION Filed March 10, 1936

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ATTORNEY. Patented May 23, 1939 2,159,234

UNITED STATES PATENT OFFICE 2.159.234 GAS-PRODUCNG NONOETONATING COMPOSTON James Taylor, Saltcoats, Ayrshire, Scotland, as signor to Imperial Chemical Industries Lim ited, a corporation of Great Britain Application March 10, 1936, serial No. 68,143 In Great Britain March 11, 1935 9 Claims. (Cl. 52—14) The present invention relates to gas pressure is not capable of sustaining its decomposition at operated devices, for example to mechanical de Ordinary pressure when heated locally, for ex vices such as piston-actuated mechanism or to ample by means of a fuzee. On the other hand, blasting cartridges of the kind comprising a pres a mixture in the same form of 80 parts by weight 5 Sure-resistant vessel and a pressure-responsive of ammonium nitrate and 12 parts by weight of 6 venting device, and in particular to new and im charcoal burns quite easily at ordinary pressure proved charges for such devices. The invention when ignited by a fuzee, the proportion of am relates in particular to Such charges comprising monium nitrate in this case being only sufficient compositions in which ammonium nitrate is the to oxidise the carbon to carbon monoxide. The 10 principal or Sole gas producing agent. former composition under pressure shows a 0 When ammonium nitrate is heated to a ten greater liability to detonation than the latter. perature between 160° C. and 260° C. unconfined An object of the present invention is the pro and under ordinary pressure, a decomposition into vision of improved charges for gas-pressure nitrous oxide and water takes place which, al Operated devices. A further object of the present 5 though exothermic, requires a continuous supply invention is the provision of improved blasting is of heat for its maintenance. This reaction is a devices of the kind hereinbefore described. A well-known laboratory method for preparing further object of the invention is the provision nitrous oxide, and experience has shown that in of improved charges for gas pressure operated carrying out the preparation an excessive Supply devices, which charges include compositions ca of heat should be avoided, since the annonium pable of undergoing a self-sustained decomposi- 39 nitrate may otherwise itself detonate. If to am tion without detonation when ignited with the monium nitrate there is added a combustible aid of a local and limited heating element. material, e. g., a carbonaceous material or a According to the present invention a charge finely divided metal, capable of undergoing rapid for gas-pressure operated devices of the kind 25 oxidation by the available oxygen of the am described comprises a gas-evolving composition 25 monium nitrate, the decomposition of the result and a non-detonating igniting element insuf ant mixture is more highly exothermic than that flicient of itself to effect any substantial general of the ammonium nitrate alone. Like ammonium. rise in the temperature of the charge, the said nitrate itself, such mixtures are often too in gaS-evolving composition consisting essentially or 30 Sensitive to be ignited or to be capable of self largely of ammonium nitrate and containing as 30 sustained decomposition merely on local heating sensitiser chromic oxide or a chromium com when unconfined, and, on the other hand, some pound adapted to generate the same on heating of them at least are still more liable to detonate in the presence of the ammonium nitrate, so on heating in a confined space. The Sensitivity that the said gas-evolving composition is capable 35 to ignition and to self-sustained decomposition of undergoing a self-sustained decomposition 85 on local heating when unconfined depends on Without detonation when ignited locally and at the nature of the combustible material and on Ordinary pressure by the said heating element. the proportion thereof relative to the proportion The preferred sensitising materials for use in of ammonium nitrate. When using carbonaceous the charges of the present invention are am 40 ingredients as combustible material the tendency monium or potassium dichromates or chromates, 40 is for the sensitivity to increase with an increase but the chromates or polychromates of other in the proportion of the said carbonaceous ma alkali metals, e. g., sodium, may also be used, terial from that resulting in the formation of while lead chromate and chromic chloride have carbon dioxide to that resulting in the formation also a slight Sensitising effect and are included of carbon monoxide. As would be expected, other without the scope of the invention. It is consid- 45 factors come into question such as the state of ered that the active sensitising agent is probably aggregation and consolidation of the mixture. freshly prepared chromic oxide since it has been As an example of the influence of the propor found that the Sensitising effect of the freshly tion of ammonium nitrate on the ease of igni prepared ash obtained by heating ammonium 50 tion, it may be stated that a solid mixture of 80 dichromate diminishes after a time. It will be 50 parts by weight of ammonium nitrate and 6 understood that the charge may include in parts by weight of charcoal, although theore gredients other than ammonium nitrate which tically a balanced combustible composition in are capable of reacting with suitable chromium which there is Sufficient ammonium nitrate to compounds to generate chromic oxide on heat 55 oxidise the carbon completely to carbon dioxide, ing. Such ingredients together with said chrom- 55 2 2,159,284 ium compounds will be understood to be equiva of a considerable portion of the charge takes place lent to the chromates or polychromates referred at a temperature below that at which the unsen to above. sitised composition would have required to be The proportion of the chromate or polychro heated before it commenced to decompose. The mate required will not usually exceed 20% of the production of the pressure is thus achieved in a weight of the ammonium nitrate, but in most gradual fashion, cases very considerably smaller proportions will According to a particular form of the inven be quite sufficient. It will usually be sufficient to tion, a blasting device comprises a pressure-re employ about 1% to 10% of the weight of the sistant metal vessel fitted with a pressure-respon ammonium nitrate. The charges of the inven Sive venting device and charged in the manner 0. tion are therefore characterised by their low ash hereinbefore described with a sensitised ammoni content. Um nitrate Composition and with a non-detonat The gas-evoiving compositions used in the ing igniter. The igniter may suitably consist present invention are preferably such that, in of an electric powder fuse, but igniters of the the absence of the chromic oxide Sensitiser, they kind described in British specification No. 431,950 15 are capable of undergoing a self-sustained gas may also be employed. In blasting devices of producing decomposition without detonation this kind, the proportion of oxidisable material either when confined under pressure and ignited in the ammonium nitrate composition should with the aid of a local and limited heating ele preferably be sufficiently high to ensure that no ment, or when heated at ordinary pressure suffi appreciable proportion of free oxides of nitro 20 ciently to cause a substantial and general rise in gen is formed by the combustion. temperature. Such compositions may contain, In such blasting devices it is preferred, in gen in addition to the ammonium nitrate, a propor eral, that the proportions of ammonium nitrate tion of an oxidisable material, for example com and of oxidisable material should be such that bustible carbonace0us materialS. Suitable OXi little or no carbon monoxide is formed among the 25 disable materials are starch, charcoal, peat, wood combustion products. Particularly for safety meal, plant fibre, natural and artificial resins, blasting in fliery or dusty mines however, the pro Waxes, bitumens, hydrocarbons, Soaps, faits, Oils, portions of ammonium nitrate and oxidisable ma and many other organic materials, less combusti terial should be so adjusted that the carbonaceous ble or incombustible materials such as formalde materials present are burnt practically complete 30 hyde polymers, ammonium carbonate and bicar ly to carbon dioxide and water. Annonium bonate, ammonium oxalate, urea, guanidine and nitrate mixtures of this kind are not usually other nitrogenous organic substances, or even themselves sufficiently sensitive to support their certain inorganic nitrogenous materials. Such as combustion at ordinary pressures when ignited hydrazine hydrate. Small proportions of inor With the aid of a local and limited igniting ele ganic materials Such as silica, china clay, mag ment, and consequently the present invention is nesium carbonate, chalk, or the like which are of particular value in providing suitable charges said to influence the decomposition of ammonium for blasting devices of the kind described. nitrate may also be included if desired. In preparing compositions for blasting in this The sensitising chromium compound is prefer manner and especially for use in fiery or dusty 40 ably distributed uniformly throughout the gas mines, incombustible materials, for example ann evolving composition, and the sensitised material monium carbonate or bicarbonate or other in may be manufactured by admixing the chromi combustible materials yielding a high gas volume um compound With the ammonium nitrate either on oxidation, are particularly useful as materials before or after the addition to the latter of any for reacting with the excess oxygen of the am 45 other ingredients that may be desired. The ad monium nitrate composition. Such materials as mixture is conveniently effected by a milling Op ammonium carbonate or bicarbonate, which are eration, o themselves decomposable by heat With the pro In the charges of the present invention the duction of gases, may themselves be introduced sensitised composition is ignited with the aid of a in greater quantities than that required for the 50 local and limited igniting element, i. e., one which oxygen balance, and then serve a useful purpose is insufficient of itself to effect any Substantial in contributing to the preSSure developed and in general rise in the temperature of the charge. moderating the temperature attained. Moderate The igniting element employed should be non quantities may usually be introduced by simple detonating in character and must be capable of admixture, but when it is desired to introduce 5 5 generating a flame, flash, Spark or the like in considerable proportions of such materials, it is contact with the gas evolving composition. As often convenient to employ a portion at least of examples of such an igniting element there may the ammonium carbonate or the like in granular be mentioned an electric powder fuse, a safety form well distributed throughout the remainder electric igniter or a small Smokeless powder or of the composition which may itself be in powder 60 cordite charge ignited in turn by a fusehead or or in granular form and which contains the am peression cap. It will be understood that the monium nitrate and sensitiser and advantageous use of a percussion cap in this manner for ac ly also enough carbonaceous material to balance tuating the flame producing igniter is not equiva the mixture. ent to the use of a detonator and does not in In the blasting devices of the present inven volve any risk of detonation of the gas evolving tion the ammonium nitrate composition used may composition. consist of any of the exothermic gas-evolving It will be understood that in using the charges compositions set forth in British specification No. of the present invention, the pressure under which 430,258, corresponding to U. S. application Serial the gas is generated will rise very considerably No. 712,052, filed February 19, 1934, including 70 as the decomposition proceeds, but it is a charac ammonium nitrate, guanadine nitrate, urea ni teristic feature of the invention that the presence trate, and dicyandiamidine nitrate, either alone of the sensitising agent does not appreciably af Or in mixtures. According to the Said specifica fect the liability of the composition to detonate tion these gas-evolving compositions are em under ordinary conditions. The decomposition ployed in conjunction with a non-detonating 75 2,159,284 3 heáting composition in substantial amount. Ac Eacampile 2 cording to the present invention, however, the gas-evolving compositions are employed in the A mixture of 80 parts ammonium nitrate pow presence of a chromium compound as sensitiser der, 8 parts powdered potassium chromate, 2 parts so that the compositions are rendered capable of starch and 1 part china clay were milled together supporting their own decomposition when ignited until the ingredients were thoroughly mixed. In with the aid of a local and limited heating ele to the resulting powder there was stirred one ment, e. g., a 30 to 100 grain powder fuse. third of its weight of ammonium bicarbonate When the blasting devices as above described granules. The composition was used in a blast O are to be used in fiery or dusty mines it is de ing device in the manner described in Example 1 sirable that any combustible organic ingredients and the so charged device was suitable for use in O present should be rendered incapable of being a fiery or dusty mine. projected in flaming particles capable of igniting Eacample 3 dangerous atmospheres, in order to minimise the 5 risk of any such ingredients being vented while A mixture of ammonium nitrate, starch, am unconsumed or only partly consumed and still monium dichromate and china clay in the pro 15 burning or taking fire. Such fireproofing may be portions 80:2:5:1 was milled with a sufficient effected by impregnation with fireproofing salts, quantity of water to make a stiff paste for half for example ammonium phosphate or sulphate, an hour and then spread out in layers about 'A' 20 sodium tungstate, alum or bora.X. thick and dried. The dried cake was broken down According to a further form of the present in and sieved, the granules retained on a sieve hav 20 vention a gas-pressure operated mechanical de ing 20 meshes to the inch but passing a sieve of 6 vice, for example piston actuated mechanism or meshes to the inci being taken. The granulated the like, includes a suitable gas-generating vessel material was mixed with one third of its weight or container and a charge of a sensitized am of ammonium bicarbonate granulated to about monium nitrate composition and a non-detonat the same size. A charge of 215 gms, of the con ing igniting element as hereinbefore described. posite mixture were loaded into a pressure resist In this form of the invention it is usually desirable ant steel tube blasting device having a capacity that the proportion of oxidisable material should of 680 ccS. and venting at a pressure of 12 tons/sq. 30 not only be sufficient to prevent the formation of in., there being also included an electric powder free oxides of nitrogen or other corrosive gases, fuse containing 00 grains of blackpowder as 30 but also to yield a relatively high proportion of igniting agent. The charged device when tested permanent gas. In the oxidation of a material by firing in a gallery containing 9% methane air composed of carbon and hydrogen and whether mixture or containing coal dust gave no ignition. or not containing a proportion of oxygen in its Eacample 4 composition; complete oxidation to carbon di 3. 5 oxide and water yields a smaller volume of per This example illustrates the use of fireproofed manent gas than oxidation to carbon monoxide WOOdmeal. 10 parts of woodmeal were soaked in and hydrogen, since in the latter case no dimini a solution containing 2 parts by Weight of an 0 tion in the volume of the products due to the con monium sulphate and 2 parts by weight of di densation of water vapour would be experienced. ammonium hydrogen phosphate dissolved in as 40 In the operation of a mechanical device this may little water as possible, mixing up the Woodmeal be of some importance, and accordingly it will not with the solution for some hours. The fireproofed usually be desirable to minimise the formation of Woodmeal was then dried, and mixed into a mix carbon monoxide as in the case of blasting. ture of ammonium nitrate, basic magnesium car The invention is further illustrated by the fol bonate and ammonium dichromate in the propor lowing examples in which the parts are parts by tion of 5 parts woodmeal to 7 parts ammonium weight. nitrate and A part each ammonium dichromate Eacampile 1 and basic magnesium carbonate. The mixture was used in a blasting device in the manner de 100 parts of ammonium nitrate were milled scribed in Example 1, the igniter consisting how with 6 parts of ammonium dichromate and 6 parts of charcoal in an edge runner mill until the ever of a 60 grain powder fuse. The charged ingredients were well distributed, the charcoal device was suitable for use in fiery or dusty mines. being added after the ammonium nitrate and an Eacampile 5 monium dichromate had been lightly mixed. The 7 parts mineral jelly were mixed into a pre 5 5 loose powder when made into a loose train A' viously prepared mixture of 80 parts ammonium deep was found to be capable of supporting its nitrate and 8 parts of ammonium dichromate, own combustion when ignited at one end by and the mixture was pressed into the form of a means of a fuzee, whereas a composition made in pellet. This composition is capable of supporting similar fashion containing only the ammonium its own combustion with the evolution of carbon 60 nitrate and the charcoal failed to support its com dioxide and water vapour and was associated with bustion when similarly ignited. In order to take an igniter consisting of a small silicon saltpetre up the excess oxygen of the mixture and provide charge itself ignited by a percussion cap. The a further source of gas pressure and reduce the resulting charge was suitable for use in gas pres temperature of combustion somewhat there was further incorporated into the composition con sure operated mechanical devices. taining the three ingredients 20 parts of arm Eacampile 6 monium bicarbonate. The powder So obtained A charge as in Example 5 included a composi was still capable of Supporting its combustion tion prepared by pressing into the form of a car when locally ignited. A quantity of the powder tridge a mixture containing 80 parts ammonium 70 was enclosed, together With an igniter consisting nitrate; 10 parts bitumen and 5 parts ammonium of a 100 grain powder fuse, in a pressure resist dichromate. Somewhat slower burning composi ing vessel having a pressure responsive venting tions were obtained by using the ingredients in device. The so charged device was suitable for the proportions 80:5:5 and 80:2:3 instead of non-Safety blasting purposes. 80:05, 75 4. 2,159,23. Eacample 7 um chromate, ammonium dichromate, and alkali metal polychromates. Acharge as in Example 5 included a composition 2. In a pressure-operated device, in combina made by pressing into the form of a rod a mixture tion a pressure-resistant, pressure-responsive of 80 parts ammonium nitrate, 5 parts paraform container, deflagrating ignition means and a de 5 5 aldehyde, and 5 parts ammonium dichromate. flagrating gas-generating composition capable of In order to disclose this application of my in undergoing self-sustaining decomposition without vention more clearly, reference is made to the detonation, said composition comprising ammoni appended drawing which illustrates a preferred um nitrate, a carbonaceous Substance which COm embodiment thereof. It is to be understood, how bines exOthernically with Oxygen and from ap () 0 ever, that this is done by Way of illustration and proximately 1 to 20% of a substance comprising is not to be regarded as a limitation upon the at least one member of the group consisting of scope of my invention. chronic oxide, alkali metal chromates, ammoni Referring to the drawing, the blasting device um chromate, ammonium dichromate, and alkali illustrated comprises a strong steel container. , metal polychromates. provided at one end with a firing head 2 Sepa 3. In a pressure-operated device, in combina rated from the container by a sealing washer 9 tion a pressure-resistant, pressure-responsive of fiber or other suitable material such that a container, deflagrating ignition means and a de seal which is gas-tight at very high pressures is flagrating gas-generating composition capable of assured. The firing head 2 is provided with elec undergoing self-sustaining decomposition without 20 20 trodes 7 and 8, one of which (8) is in metallic detonation, said composition comprising at least connection with the firing head 2, while the other one substance selected from the group consisting electrode (7) is insulated therefrom. The mount of ammonium nitrate, guanidine nitrate, urea ing of the insulated electrode is such as to allow nitrate and dicyandiamidine nitrate; a carbona no gas leakage at pressures up to about 25 tons ceous Substance which combines exothermically 25 2 5 per square inch. Terminals 10 and 1 are provid With Oxygen, and at least approximately 1% of a ed for the electrodes which are used in initiating Sensitizing agent comprising at least one member the cartridge electrically. A protective steel cap 3 of the group consisting of chromic oxide, alkali having an aperture 4 for the leads of the ter metal chromates, ammonium chromate, ammoni minals from the blasting machine or other Suit um dichromate, and alkali metal polychromates. 30 30 able source of electric energy, is screwed on the 4. In a pressure-operated device, in combina firing head 2. tion a pressure-resistant, pressure-responsive The blasting charge f3 comprising any of the container, deflagrating ignition means and a gas-generating compositions in accordance with deflagrating gas-generating composition capa my invention, for example the composition of ble of undergoing self-sustaining decomposition 35 35 Example 1, is introduced loosely into the tube in Without detonation, said composition comprising the required amount. On the shoulder of the at least one substance selected from the group container remote from the firing head 2 is placed consisting of ammonium nitrate, guanidine ni a fiber or light sealing washer 6 and a steel burst trate, urea nitrate and dicyandiamidine nitrate; ing disc 5 adapted to be ruptured at a predeter a carbonaceous substance which combines ex 40 4) mined and considerable pressure, both of these othermically with oxygen, and from 1 to 20% devices being held in position by the hollow Screw Of a Sensitizing agent comprising at least one in cap 4, which is pierced with suitable channels member of the group consisting of chronic ox for venting the gases and directing and distribut ide, alkali metal chromates, ammonium chro ing the blast. An electric powder fuse or safety mate, ammonium dichromate, and alkali metal 45 45 igniter 2 containing, for example, 30 grains of polychromates. block powder, is used for ignition and provided 5. In a preSSure-operated device, in combina with long leads from the electrodes 6 and 7 and tion a pressure-resistant, pressure-responsive positioned as shown in the drawing so that the container, deflagrating ignition means and a flash is directed toward the firing head. By so deflagrating gas-generating composition capable 50 positioning the cap, the tendency of the adjacent of undergoing Self-sustaining decomposition charge to be forced into the plug at the end near With Out detOmation, Said COmposition compris est the cap 4 is overcome. ing ammonium nitrate, a carbonaceous material For convenience, the device has been shown in and at least 1% of ammonium dichromate, 5 5 the upright position, but it will be understood 6. In a pressure-operated device, in combina that the charge 3 would only assume this posi tion a pressure-resistant, pressure-responsive tion if the device were horizontal. In practice, container, defiagrating ignition means and a the device may be used in any position So long as deflagrating gas-generating composition capa ble of undergoing Self-Sustaining decomposition there is effective contact between the fuse 2 and 60 60 the charge 3. without detonation, Said composition compris Having now particularly described and ascer ing at least one substance selected from the group tained the nature of my said invention and in consisting of ammonium nitrate, guanidine ni what manner the same is to be performed, I trate, urea nitrate and dicyandiamidine nitrate; declare that what I claim is:- a carbonaceous material, and from 1 to 20% 1. In a pressure-operated device, in combina of a sensitizing agent comprising at least one 65 tion a pressure-resistant, pressure-responsive member of the group consisting of chronic ox container, deflagrating ignition means and a de ide, alkali metal chromates, ammonium chro flagrating gas-generating composition capable of mate, ammonium dichromate, and alkali metal polychromateS. undergoing self-sustaining decomposition With 70 70 out detonation, Said composition comprising am 7. In a presSure-Operated deVice, in combina monium nitrate, a carbonaceous Substance which tion a pressure-resistant, pressure-responsive combines exothermically with Oxygen and at least container, deflagrating ignition means and a approximately 1% of a Substance comprising at deflagrating gas-generating composition capa ble of undergoing self-Sustaining decomposition least one member of the group consisting of 75 75 chromic oxide, alkali metal chromates, ammoni Without detonation, said composition comprising 2,15934 5 at least one substance selected from the group tion capable of undergoing a self-sustaining de consisting of ammonium nitrate, guanidine ni composition without detonation, said composi trate, urea nitrate and dicyandiamidine nitrate; tion comprising at least one substance selected a carbonaceous material, a cooling salt, and from from the group consisting of ammonium nitrate, is 1 to 20% of a sensitizing agent comprising at guanidine nitrate, urea nitrate, dicyandiamidine least one member of the group consisting of nitrate; a carbonaceous material, and from chromic oxide, alkali metal chromates, am to 20% of a sensitizing agent comprising at monium chromate, ammonium dichromate, and least one member of the group consisting of alkali metal polychronates. chromic oxide, alkali metal chromates, am O 8. The combination of claim 7, in which said monium chromate, ammonium dichromate and cooling salt comprises ammonium bicarbonate. alkali metal polychromates. 10 9. A non-detonating gas generating composi JAMES TAYLOR,

CERTIFICATE OF CORRECTION. Patent No. 2,159,25). May 25, l959. JAMES TAYLOR It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page li, sec ond column, line 5, for the word "without" read within; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office. Signed and seal?d this llth day of July, A. D. 1959. Henry Wan Arsdale Acting Comissioner of Patents.