US2365170A - Blasting explosive - Google Patents

Description

Patented, Dec. 19, 1944 2 ,365, 70

UNITED STATE-S PATENT OFFICE 2,365,170 I r r g BLASTINGEXPLOSIVE poration oi Delaware No Drawing. Application April 13, 1940, Serial No. 329,492

11 Claims. (01. 52-13) 'l 'his invention relates to gelatin dynamites of I improved explosive properties and more particularly to gelatin dynamites in which the improvement' results ,from the incorporation therein of fairly well established that this results because the apparent density of the gelatin has increased, approaching the theoretical density of the uni..- ture of ingredients used.

"*plish this without seriously departing from the basic characteristics of gelatin dynamites, which involve in addition to water resistance, high density and plasticity. A still further object of low density, cellular, carbonaceous ingredients 5 this invention is to provide a low density, celluwhich have been specially treated to provide lar, carbonaceous ingredient, which when incorstiiiened cell walls. porated in a gelatin dynamite, will prevent ex- For use in blasting under wet conditions, or' I cessivecompression under high pressures. Still at various depths under liquid heads such as, for further objects will appear hereinafter. example, water and oil, blasting gelatin and The objects of this invention are accomplished gelatin dynamites have long been used. As is in accordance with this invention by using low well known in the art, gelatin dynamites condensity, cellular, carbonaceous ingredients, sist of a plastic explosive formed by the gelatintreated with a material which will effectively ization of nitroglycerin with nitrocellulose to stifien the ingredient so that the cell structure which mixtures may be added oxidizing salts and 15 will not be destroyed under high liqui D carbonaceous ingredients. These compositions sures, as an ingredient in gelatin dynamite. are especially resistant to the penetration of water We shall within this specification and claims and for that reason are particularly useful for use the term gelatin dynamite to include the blasting under liquid heads. three main classes of gelatin dynamites which are Difiiculties have been encountered in the past commonly known as straight gelatins, ammonia with gelatin dynamites becoming insensitive after gelatins, and permissible gelatins. The straight prolonged storage and when used under the great gelatlns range. in stren th, ac d t the sual depths of water and oil'such'as are encountered, terminolo y. fr m to 100%. The latter is for example, in seismographic prospecting and oil commonly know as blasting atin. These well shooting. In the latter case, it has been 29 ordina y contain a elatini ed liquid e plos ve ingredient, with varying proportions of sodium nitrate and combustibles, depending on the strength and other properties which may be required. The ammonia gelatinsusually contain a This dimculty has been overcom to a, certain 30 smaller lii'OPOl'tlOnDf gelatinized liquid explosive extent by the incorporation of suitable low density: ingredients in the gelatin dynamite. However, when such gelatin dynamites are used under the highheads of liquid that are prevalent in oil well shooting and -seismographic prospectof explosive compositions of improved sensitive- -ness under adverse conditions. A further object of this invention is the preparation of gelatin dynamites which will function successfully after more or less prolonged subjection toimmersion under great depths of water or other liquids. A still further objector this invention is toaccomthan straight gelatins oi the same grade strength, the strength being made' up by the use of ammonium nitrate. Permissible gelatins may be of g either the straight or the ammonia type. with the addition of a safety ingredient which permits their safe use in coal, mines, where there is danger of explosion from mine gas and coal dust.

We have found that the low density, carbonaceous ingredients, prepared in accordance with the 'copending application of Lawrence Serial No. 326,654, produce a gelatin which will suffer less than the usual degree of compression under high pressures. carbonaceous ingredients which are suitable for this purpose include ground cork,

balsa, bagasse, bongo wood, hemp hurds and their equivalents. The treatment to which they are subjected involves impregnation of the ingredients .to eiiect a stiffening oi the cell walls with a heat-hardening synthetic resin such as the urea-aldehyde, phenol-aldehyde, thioureaaldehyde type resin and the like, and substantially heat-hardening in situ: The synthetic resins may be formed and hardened on and in the carbonaceous ingredient or applied as an intermediate condensation product, from a solution high liquid pressures and the density is often lower than is desirable. By using treated carbonaceousingredients, a considerably greater improvement in sensitiveness under high liquid pressure is secured with a small quantity of low density material and at thesanie time gelatins of the desiredhigh density are produced. 'I'hus,

by the prior art gelatine 'dynamites can-be prepared which will have a density of 1.3 g./cc. or less and will shoot after 2 hours under 120 lbs.

- per sq. in. (275 it.) of water by incorporation of 4% of ordinary ground cork. However, incorporation of 2-3% of treated cork will give gelatins having a density of 1.4 g./cc. or more which will shoot after 2 hours under at least 250- lbs/sq. in. (580 ft.) oi. water. i

Our invention makes it possible to prepare gelatin dynamites economically and simply which are of greatly increased effectiveness when" used under igh presgurgs J 'Weareaware that it has been proposed to use .low density carbonaceous ingredients, which have been impregnated'with materials to reduce their nated materials when incorporated in gelatin dynamites do not effectively improve their sensitiveness under high pressures. It is to be noted that the carbonaceous materials treated to give stiffened cell walls have substantially the same absorbency for nitroglycerin before and after treatment, and in some cases there is a material increase in absorbency.

In order to show that the absorbency of treated carbonaceous material is substantially constant or increased, the following table is given:

absorbency for nitroglycerin. These impreg-' aseairo ever, essential, as samples of cork with the :tob-

lowing screen analyses have given good results.

Screen test A B C D E Per cent Per cent Per car Per cent Per cent On 12 mesh 0.6 Nil 1. 0 Nil Nil On 20 mesh 58. 5 42. 0 79, 6 1 Nil On 30 mesh 22. 5 50. 0 l5. 5 100 On40mesh 17.5 6.0 3.0 .s Through 40 mesin 1. 0 2. 0 l. G

The treatment may be carried out in the following manner. The cork is placed in a suitable container and a solution of urea in an acqueous formaldehyde solution is added to the cork and the mixture thoroughly incorporated. The mixture is then heated tocause condensation of the urea-formaldehyde resin and to dry the cork. This drying may conveniently be carried out at about IO-190 C; The impregnated cork and resin are then heated to harden the resin. This may be done by heating for to 1 hour or more at 100 C. or for shorter periods at temperatures up to 150 C. This procedure, as will be obvious to those skilled in the art, may be varied considerably.

Alternatively the urea -iormaldehyde solution may be sprayed on the hot cork and the mixture dried and the resin hardened as before, or the urea may be mixed with the cork and then the formaldehyde solution, added and drying and hardening of the resin carried out as before.

The ratio of urea to formaldehyde may be varied over wide limits, for example, from 1 part of urea and 2 parts of 40% formalin (37% formaldehyde by weight) to 1 part of urea and 5 parts of t0% formalin, although we do not wish to be limited by these proportions. Furthermore, the solutions may be diluted to any desired degree, although for economy of operation, it is desirable to use quite concentrated solutions.

Instead of preparing the resin in above de-- scribed manners, a partial condensation product of urea and formaldehyde may be prepared by methods well known in the art which can be applied from an aqpeoussbl'flion' or "from solution in an Manic solvent such as ethyl alcohol, the

. carloonaceous material treated, the solvent evaporated, and the resin heat-hardened.

In treating cork with urea-formaldehyde solution, good results have been obtained when the quantity used was such as to give a final product TABLE I Per cent absorbency Absorbency factor Ingredient R i R i cs 11 cs 11 Plain treated Plain treated Cork 37.1 45.0 59 a2 Balsa 76. 2 76. 0 320 317 Bagasse-Celotex. 78. 0 76. 0 355 317 Bagasse-Godchaux 68. 0 65. 4 212 189 containing from about 15% to about 45% oi resin. The preferred range is from about 30% to about 40% resin. by weight'of the final treated cork.

Other carbonaceous ingredients such as balsa, bongo wood, or bagasse may be used, but when these types of materials are used, it is found that a lower percentage of resin will give results which areas effective as higher percentages with ground cork. Thus, for examplawith treated balsa, it is preferable to have about 25% to about 35% of urea-formaldehyde resin ,by weight of the final product. This urea-formaldehyde resin treated balsa orits equivalent may be used in explosive compositions in the same manner that the ureaiormaldehyde resin treated cork is used to ob-' tain explosives with approximately the same properties.v

In the use of the phenol-aldehyde resins to treat cork, the most satisfactory results are obtained when the resin is formed in and on the cork cells. For example, cresol may be dissolved in 37% formaldehyde solution, catalyst stirred in and the mixture added to the cork, By heating A treating are the following:

the mixture of the cork with the cresol and form.-

aldehyde, condensation, drying and hardening of the resin are accomplished. The final hardening operation can be carried out at temperatures in the range of -100-150 c,

Other heat-hardening resins or combinations may be used to treat the cellular material, for

concentrated solution of these materials in an I organic solvent. This has the advantage of limiting the quantity of solvent used, thus reduce ing the fire hazard and eliminating the necessity of installing a recovery system for the solvent.

The carbonaceous ingredients such as cork,

balsa, bagasse, etc., treated with a suitable heathardening resin have ahard, rather gritty feel in contrast to the soft and compressible qualities ofthe untreated material. Incorporation of these ingredients in gelatin dynamites tothe extent of about 2-3% results in greatly improved ability to detonate under conditions of high water pressure.

In the preparation of the specially treated carbonaceous material, two factors are of especial importance: Mixing with the resin ingredients in a relatively low viscosity phase to insure thorough incorporation and subsequent hardening of the resins to form a hard, tough coating on the surfaces of the cell walls thus creating resistance to compression.

Several examples of the carbonaceous material used in this invention are shown in the following examples.

EXAMPLE 1 A quantity of ground cork was treated with urea-formaldehyde resin in the following manner. The cork, 354 lbs., was placed in a pan dryer and heated to about 150-160 F. Meanwhile, a solution was prepared by dissolving 135 lbs. of urea in 402 lbs. of a 37% (by weight) aqueous solution of formaldehyde. This solution was then sprayed on the hot cork, which was being constantly mixed by rotating plows, over a period of about /2 hour. Heating was continued until the cork was dry and the temperature had reached about 200 F., a period of about seven hours. The cork was then discharged from the dryer and after cooling was ready for use. The quantity of impregnated cork obtained'was 549 lbs. and contained 38.3% of resin. The cork showed the following screen analysis:

Other properties of the cork before and after Per cent On 12 mesh 2 On 20 mesh. 38 On 30 mesh 36 On 40 mesh -l l4 On meshf 4 Thorugh 60 mesh 6 The treated cork feels crisp and hard in contrast to the softness of the ordinary granulated cork. v

Five hundred parts by weight of ground cork was mixed with 700 parts by weight of 37% (by weight) formaldehyde solution to which 26 parts by weight of concentrated hydrochloric acid had been added to serve as catalyst. Two hundred sixteen parts by weight of cresol was added and the whole mixed together. The treated cork mixture was then dried and theresin hardened by heating for seven hours in an oven at about 135 C. A yield of .706 parts by weight of treated cork containing 33% of resin was obtained.

EXAMPLE 3 treated cork containing 36.5% of resin was obtained.

' EXAMPLE 4 Five hundred parts by weight of ground balsa wood was placed in a steam-jacketed kettle equipped with a stirring device. A solution of 126 parts by weight of urea dissolved in 580 parts by we'ght of 37% (by weight) formalin solution was added to the balsa and the mixture was stirred for half an hour. Then the kettle was heated for 4 hours with steam to effect the resin reaction and to dry the mixture. The mixture was finally heated with lb. steam for about two hours to complete the drying and harden the resin. A yield of 665 parts by weight of balsa,

containing about 28.5% of resin, resulted.

Per cent On 12 mesh"-.. 1.0 On 20 mes 39.5 On 30 mes 20.5 On 40 mes 12.5 Through 40 mesh 26.5

\ EXAMPLE 5 Fivehundred parts by weight of cork was mixed with 420 parts by weight of'a 60% solution of an alcohol-soluble urea-formaldehyde resin Formite F-224) and dried two hours in thin layers in an oven at C. A yield of seven hundred two parts by weight of treated cork containing 33% ofresin was obtained.

Examine formaldehyde soltion was added with stirring to Untreated Treated o. 09 1 0.19 5. Q 1. 2 cork so a Resin content -.per cent" 1 3823 ofdry weight. f

the bagasse.

Steam was applied to the jacket and the material was dried and the resin hardened during a period of 4 hours. About 693 parts by weight of treated bagasse containing 31% of resin was obtained. a

Treated cork 3 Treated cork 7 L...

Chalk 1. 1. 0 l. 0

Density, gin/cc 1. $6 1. 41 Sensitivenoss:

Shot after 2: hrs. at y lbs/sq. in. 2 at 67 2 at 250 2 st 150 Fivehundred parts by weight of cork was mixed with resolution of 125 parts by weight of 20 cp. chlorinated rubber and 125 parts by weight escorts (100% gelatin mite, Table 4), and in extra geletins of 607;, Table 5. These selatlns were tested. fortweter-resistance by the procedure given hereinbefore. The first gelatin in each table is a of Bakelite 3560 in 500 parts by Weight of toluene. formulated according to commercial composi- The mixture was placed in an oven end dried for 0118, but th hers 11mm 0111 treated low a. period or 2 hours at 135 c. About 720 parts density. cellular, carbon ceous m terial. Excmie by weight of treated curl: contoinind 34% of resin nation of these data. shows the very marked in was obtained. provement resulting from the use of the treated The carbonaceous materials described emve cerbonsceous materiel.

Tonto 2 60% gelatin dymmites Nitroglyoorin Nitrocellulose. Sodium nitrate Wood pulp Balso pulp Ivory meaL Wheat flour. Untreated cork.- Treated cork l l Treated cork 2 Treated balsa 4 Treated bagasso 5 Treated bagasse 6 1.5!. 1.51 1.46 1.52 1.52 K 24atl50 24atl50 seem 24atl60 21124120 24atl50 2at250 l The following list gives the compositions ofthotreated carbonaceous materials:

, Treated cork l38.3% urea formaldehyde resin Treated cork 233% cresol (ormaldeh do resin Treated cork 3-36.47 thlourea lorma dohyde resin Treated balsa 4-28A o urea formaldehyde resin Treated bagssse 5-3l% urea iormaldehyde resm Treated bagasso 6-35.6% urea formaldehyde resin Treated cork 7-347 resin consisting of equal parts of chlorinated rubber and a heat-hardening phenolic resin have been used to produce greatly improved gela- It will be noted that in the above table the tin dynamites. The various dynamite compositreated material used gives actual materiel contions prepared by using the treated carbonaceous materials were tested for underwater use by placing three '2 x 16 sticks of the gelatin dynamite composition; end to end in a steel pip capped at the lower end. A No. 6 or No. 8 electric blasting cap was inserted in the first stick of gelatin dynamite and the pipe filled with water. The blasting cop wires were'fastened to the terminalsof arsparkplug mounted in a pipe cap. This cap was screwed on to the pipe and the pressure in the pipe was built up by applying compressed air through a valve. Any desired pressure within reason may be obtained in this way. The pipe or bomb containing the gelatin under water pressure was allowed to stand for any desired period of time, and then laid horizontally on top of 5 lead cylinders, 1 in. diameter and 2 in. high, each covered with a steel disc of the same diameter. These five lead cylinders I were spaced at intervals i'under the pipe and the charge fired. If the charge shoots completely, all

or the lead cylinders are compressed to a coa siderable degree, for example, as much as an inch or more. If the detonation does not prop completely, the cylinders under the portions of the charge which fail will not be compressed; in

lations, which give the results of its use in the socalled,L. F. (low freezing) gelatins (60% imd 80% strengths, Tables. 2 and 3), in blasting. gelatin gelatin TABLE 3 L. F. gelatins Nitrogl oerin e1. 0' o. o N itr ulose. 2. 6 12. 5 18. 5 1s. 5 2. 0 2. 0 4. 0 4. 0 l. 5 1. 5 l. 5 -1. 5 1. 0 1. 0 Untreated mr 2. 0 Treated cork 1.. c 2.0

x 100.0 100.0 Sensltivenoss: Shot after hrs. at I lbs/sq. in..

pressure"; 2 at $3 2 at q TABLE 4 Blasting gelatin Niirogl oerin 89.0 at. Nitrooe ulose 6.0 6. Balsa 4. 0 Treated cork 1--.. 4. Chalk 1. 0 1.

Sensitivoneasz, Shot aims hrs. at y lbs/sq. in.

pressure I 2 at 43' 2 at 87 tent, exclusive of resin, 01- about 2%, except in Example G where net corkcontent is about 1.25%.

Nitroglycerin TABLE 60% ammonium nitrate gelatin Nitrocellulose Sodium nitrate fur Untreated cork Treated cork 1 2. 0

D enslty, gut/cc Sensitiveness: Shot after 1' hrs. at 1,!

lbs/sq. in

In order to show the decrease in compressibility of the gelatin dynamites containing the treated carbonaceous materials, the following test was conducted. A section of gelatin dynamite 2 inches in diameter and 2 inches long was placed under kerosene, or other suitable liquid, and the volume thereof determined. The liquid was then subjected to pressure, for example, 75 lbs/sq. in. gauge for minutes, and the volume of the sample observed. The theoretical reduction of the gelatins volume which should result from the above pressure was then calculated from the theoretical maximum density and its actual bulk density. The actual compressibility of the gelatin was then erpressed as a relative compressibility? i. e., the ratio of the observed decrease in volume to the theoretical decrease. The results on a number of gelatin samples containing treated cork are given in Table 6 which show that the relative compressibility decreases as the ability to shoot under pressure improves.

Cork l-33.8%resin consisting of chlorinated rubber and 50% phenolic aldehyde resin.

Cork 2-32.7%urea-forrnaldehyde resin.

Cork 339.6%-urea-iormaldehyde resin.

1 Each gelatin contains a quantity of'treated cork equivalent to 2% actual cork.

In the above formulations where the use of nitroglycerin is indicated, it should be understood that by the term nitroglycerin is meant either this compound by itself or with the addition or partial substitution of any of the commonly used freezing point depressants such, for example, as ethylene glycol dinitrate, nitrated polymerized glycerin, nitrated sugars, nitrated chlorhydrins, etc. 'The term nitroglycerin as here described is well accepted-in the explosive art.

The explosive. compositions of our invention have been found especially advantageous in blasting operation where there is a substantial liquid head above the explosive charge. In dee well blasting such as, for example, seismograph pros pecting, quarrying and oil well shooting,/ these compositions have proved invaluable since their sensitiveness is not impaired under the high'pressures encountered. The compositions have also found use in underwater operations, such as are carried out in channels and harbors, due to their constant sensitivity.

It will be understood that the details and examples hereinbefore set forth are illustrative only, and that the invention as broadly described and claimed is in no way limited thereby.

What we claim and desire to protect by Letters Patent is:

1. A gelatin type explosive composition which includes as ingredients nitroglycerin and a cellular, carbonaceous material selected from the group consisting of cork, balsa, bagass, bongo wood and hemp hurds and treated with a synthetic resin heat-hardened in situ, said treated carbonaceous material characterized by having stifiened cell walls and by having substantially the same-nitroglycerin absorbency as the un treated material.

2. A gelatin type explosive composition comprising a stiffened, cellular, carbonaceous mate-- rial selected from the group consisting of cork,

balsa, bagasse, bongo wood and hemp hurds, said material treated with a synthetic resin heat hardened in situ, and characterized by a nitroglycerin absorbency substantially equal to the absorbency of the untreated material and said composition containing less than about nitroglycerin, said composition characterized by a density greater than 1.4 grams per cc., and the ability to detonate after 2 hours at 200 lbs. 8. sq. inch water pressure when disposed in a 2 x 48 inch column.

3. A gelatin type explosive composition com prising a stiffened, cellular, carbonaceous material selected from the group consisting of cork, balsa, bagasse, bongo wood and hemp hurds, said material treated with a synthetic resin heat: hardened in situ, and characterized by a nitroglycerin absorbency substantially equal to the absorbency of the untreated material and said composition containing between about 40 and about 60% nitroglycerin said composition characterized by a density greater than 1.4 grams per cc., and the ability to detonate after two hours under 200 lbs. per sq. inch water pressure when disposed in a 2 x 48 inch column.

4. An ammonium nitrate gelatin dynamite composition comprising a stiifened, cellular, carbonaceous material selected from the group consisting of cork, balsa, bagasse, bondo wood and hemp hurds, said material treated with a synthetic resin heat-hardened in situ, and-charac- .terized by a. nitroglycerin absorbency substantially equal to the absorbency of the untreated material and said composition containing less thanabout 40% nitroglycerin said composition characterized by a density greater than 1.5 grams per cc., and the ability to detonate after 2 hours at lbs.'per sq. inch water pressure when disposed in a 2 x 48 inch column.

5. A gelatin type explosive composition com prising a liquid explosive, nitrocellulose, and between about 1.25% and about 4.0% of 9. treated cellular carbonaceous material selected from the group consisting of cork, balsa, bagasse, bongo wood and hemp hurds, having the cell walls thereof stiffened with a synthetic resin heat hardened in situ, said resin comprising between about 15% and about 45% by weight of said material.

6. A gelatin type explosive composition comprising a liquid explosive, nitrocellulose, and between about 1.25% and about 4.0% of a treated cork. having the cell walls thereof stiffened with said resin comprising between about 15% and about 45% by weight of said material. 7

'7 A gelatin type explosive composition comprising a liquid explosive, nitrocelluloseand between about 1.25%and about 4.0% of treated ing the 'cell walls thereof stifiened with a phenol aldehyde resin heat hardened in situ, said resin comprising between about 15% and about 45% .by weight of said material.

9. A gelatin type explosive composition comprising a liquid explosive, nitrocellulose, and be tween'about 1.25% and about 4.0% or a hay 9 a phenol aldehyde resin heat hardened in situ.

ing the cell walls thereof stiflened with a urea aldehyde resin heat hardened in situ, said resin comprising between about 15% and about 45% by weight of said material.

10. A gelatin'type explosive, composition comprising a liquid explosive, nitrocellulose, and between about 1.25% and about 4.0%-0! bagasse having the cell .walls thereof stifiened with a phenol aldehyde resin heat hardened in situ, said resin comprising between about 15% and about 45% by weight of said material.

11. A gelatin type explosive composition comprising a liquid explosive, nitrocellulose, and between about 1.25% and about 4.0% 'of bagasse having the cell walls thereof stifiened with a urea aldehyde resin heat hardened in situ, said resin comprising between about 15% and about 45% by weight of said material.

1 CHARLES D. HITTING.

ROBMT W. LAWRENCE.