US3235425A

US3235425A - Slurry-type blasting compositions containing ammonium nitrate and smokeless powder

Info

Publication number: US3235425A
Application number: US67513A
Authority: US
Inventors: Fred B Clemens; Robert W Lawrence
Original assignee: Hercules Powder Co
Current assignee: Hercules Powder Co
Priority date: 1960-11-07
Filing date: 1960-11-07
Publication date: 1966-02-15
Anticipated expiration: 1983-02-15

Description

United States Patent SLURRY-TYPE BLASTING COMPOSITIONS CON- TAINING AMMONIUM NITRATE AND SMOKE- LESS POWDER Fred B. Clemens, Salt Lake City, Utah, and Robert W.

Lawrence, Wilmington, Del., assignors to Hercules Powder Company, Wilmington, Del., a corporation of Delaware N0 Drawing. Filed Nov. 7, 1960, Ser. No. 67,513

30 Claims. (Cl. 149-48) This application is a continuation-in-part of our application Serial No. 800,634, filed March 20, 1959, now abandoned.

This invention relates: to fluent water-containing oxidizer salt blasting compositions containing a smokeless powder component as a sensitizer. In one aspect this invention relates to fluent water-compatible oxidizer salt explosive compositions containing ammonium nitrate either as the sole oxidizer salt or as an ingredient thereof. In another aspect this invention relates to fluent ammonium nitrate explosives which are especially utilizable in water-containing boreholes without the need for protection from direct contact with the water. In another aspect, this invention relates to fluent water-compatible oxidizer salt explosive compositions characterized by a density sufliciently high that they can be gravitated in a water column in a borehole, and further characterized by cohesive properties which enable them to then exist in the borehole as an intact, or cohesive, mass in a detonatable state over a prolonged period. In another aspect this invention relates to a method comprising a sequence of mixing steps for the manufacture of Water-compatible oxidizer salt compositions above referred to.

In blasting methods involving the use of an oxidizer salt, e.g., ammonium nitrate, in the presence of water, it has in the past been considered necessary to maintain the oxidizer salt packaged in a dry state to assure its detonation. This invention is concerned with such blasting -compositions in which, however, the oxidizer salt exists in direct contact with Water as a component of a fluent detonatable water-containing blasting mixture, and which vary in consistency from that of an easily pourable slurry to a deformable plastic mass, and are characterized by densities greater than that of water so as to be adapted for gravitation through water and, therefore, especially utilizable for shooting in water-containing boreholes.

In accordance with the invention, fluent water-compatible oxidizer salt blasting compositions, especially suitable for utilization in water-containing boreholes without need for protection from the water, are provided, which comprise on a weight basis from about 20 to about 80 percent of an inorganic oxygen-supplying, or oxidizer, salt from about 8 to about 70 percent of a smokeless powder, and from about to about 45 percent water, and which are characterized by a density greater than that of water. Ammonium nitrate either alone or together, generally as the chief ingredient (50 percent or more), with one or more supplemental oxidizer salts, is the now preferred oxidizer salt component of our composition.

Further in accordance with the invention, a sequence of steps for admixing the ingredients of a fluent watercompatible composition above described, including that of incorporating a gel-forming agent, is provided, which comprises admixing an oxidizing salt and gel-forming agent, adding the resulting admixture to the water ingredient and agitating the resulting aqueous admixture for a period of time sufliciently long to effect substantially uniform distribution of all ingredients therein, and thereafter uniformly admixing a smokeless powder with the said aqueous admixture; the proportions of oxidizer salt, water and smokeless powder, on a weight basis, being as above described and the proportion of said gel-forming agent being from about 0.2 to 5 percent. Preferred compositions contain guar gum as a gel-linking of the often together with an agent to cause cross-linking of the guar gum in the gel to provide compositions exhibiting cohesiveness and consistency to a greater degree.

Still further in accordance with the invention, inorganic oxidizer salts, e.g., ammonium nitrate, are utilized as blasting agents in the presence of water under conditions which eliminate need for their protection from the water by employing them as a component of an explosive composition which comprises on a weight basis the above stated proportions of oxidizer salt, smokeless powder and water, and generally also containing a gel former agent in the above stated range of proportions therefor.

The explosive compositions of the invention are fluent. They vary in consistency from easily pourable slurries to nonpourable, but nevertheless, still flowable, easily deformable masses. Although our explosives in pourable form are often preferred from the standpoint of simplified handling, fluent cohesive masses of the explosive composition are more often advantageous utilized particularly when it is desired to gravitate the explosive through a water column in a borehole for detonation after a prolonged period of time as discussed hereinafter.

As described hereinafter, in most instances the consistency of the compositions is regulated to a large degree by the presence of a gel-forming agent, i.e., one which forms a gel with the water component of the explosive composition, in order to prevent any settling of components and, in preferred practice, to impart a satisfactory degree of cohesiveness so that the composition retains its form as a unit mass in the presence of water for prolonged periods. Exemplary gel-forming agents are sodium carboxymethylcellulose, mannogalactans, e.g., guar gum, methylcellulose, water swellable starches and the like.

When no gel-forming agent is present, the explosive A tures being generally from about 0.5-0.7 up to 5 weight percent. The degree of fluidity is also a function of water content as well as particle size of the solid composition components, i.e., it increases with increasing water content and to a large extent with increase in particle size of the solid composition components. I

The fluency, i.e., the degree of fluidity, of the compositions of the invention is illustrated by the beaker and slump tests described hereinafter which measure the flow of the composition as an intact coherent mass either pourable, or, in any event, plastic and deformable.

In carrying out the beaker test, a standard upright lipped 250-rnl. glass beaker, e.g., 3% inches in diameter by 2 /2 inches in height and having a A inch lip, or other suitable such container, is completely filled with the composition, under room temperature conditions, and

* I.e., at about 20 C.

then placed longitudinally on its side on a horizontal surface to permit the composition to flow onto the said surface from the open end of the beaker. The time required for the composition to flow a specified distance along the horizontal surface, i.e., away from the beaker in an axial direction, is measured as an index of the fluidity of the composition. In carrying out the slump test, a suitable container such as a beaker above described, is filled with the composition, and inverted on a horizontal surface under room temperature conditions, and then raised upwardly away from the horizontal surface so as to leave its contents as an upright unconfined integrated mass having its shape unaltered from that when it was confined within the beaker. Due to the fluency of the unconfined mass, it flows to a position of repose, in response to the force of gravity, with a corresponding decrease in height. The decrease in height per unit of time, i.e., slump, is measured under the room temperature conditions as an I.e., at about 20 C.

index of the degree of fluidity of the mass. In some instances, if desired, the unconfined mass can be weighted so as to slump at a somewhat higher rate.

All compositions of the invention are intact, coherent masses which exhibit fluidity measurable by at least one of the above tests. As a matter of general practice, the beaker test is applied to the more fluent, and the slump test is applied to the less fluent of our compositions.

As indicated in Table I, the fluency of those compositions of tests 18, 23 and 24 is illustrated with reference to the beaker test, the beaker in each instance being a standard 250-ml. beaker above described. The fluency of the composition of test 30 is illustrated with reference to the slump test, the beaker employed having a height of 3% inches and a diameter of 4 inches, the unconfined mass being initially weighted by a IOO-gram weight placed on its top end immediately upon removal of the beaker therefrom.

Particle size and type of the oxidizer salt ingredient is not generally critical. For example, ammonium nitrate can consist of prills such as used in fertilizer and which are substantially all on 20 mesh, or it can be granular and in that form, vary from coarse to fine. Other oxidizer salt ingredients are generally of comparable particle size.

The particle size of the smokeless powder ingredient varies from fine grade, for example, with about 1 percent on a 20-mesh screen and about 25 percent through 100 mesh through medium and coarse to perforated grains as large as, say about 0.5 inch long by 0.25 inch in diameter. Although a fine particle size of smokeless powder component is often employed in the practice of the invention, the selection of particle size is, to a large extent, a matter of choice, depending upon the need at hand. Higher densities are obtained more readily with larger particle size sensitizers and accordingly, the larger size sensitizer is often preferred when applied to blasting in Water-containing holes. In such event, of

course, more smokeless powder will be required for at taining a given sensitivity than if finer sized sensitizer is utilized.

Ammonium nitrate is in many instances the only oxygen-supplying salt component. However, other inorganic oxygen-supplying salts can be used, alone or with a mmonium nitrate as a supplementary oxidizer salt. Of these supplementary salts, the alkali metal nitrates are now preferred. Often, when ammonium nitrate is utilized with a supplementary salt, it comprises the said oxygensupplying salt at least in major proportion, i.e., at least 50 percent of the oxygen-supplying salt always being ammonium nitrate. Exemplary oxygen-supplying salts that can be used alone, or together with ammonium nitrate as supplemental oxidizer salt, are alkali metal and alkaline earth metal nitrates and perchlorates (including ammonium) as, for example, sodium nitrate, magnesium nitrate, calcium nitrate, potassium nitrate, barium nitrate, sodium perchlorate, ammonium perchlorate, calcium perchlorate and magnesium perchlorate. By the term oxygen-supplying salt or oxidizer, as is well known in the explosives art, is meant one which, under the conditions of the detonation, liberates oxygen for the oxygen balance required.

Preferred compositions of the invention contain from about 15 to 30 percent smokeless powder, from about 45 to 75 percent oxygen-supplying salt, from about 0.5 to 3 percent gel-forming agent, or thickener, and from about 10 to 25 percent water. In some applications the preferred range of smokeless powder is from 15 to 50 percent.

The compositions of the invention are insensitive to detonating action of a No. 8 commercial blasting cap, but are detonatable by conventional booster charges of PETN (pentaerythritol tetranitrate), RDX (cyclotrimethylenetrinitramine), Pentolite (PETN-TNT, 50/50), tetryl, Composition B (RDXTNT 60/40), gelatin dynamites and the like. One booster advantageously employed is a dispersion of a crystalline high explosive, e.g., PETN or RDX, in a plastic carrier such as described in the copending application of Alpheus M. Ball, Serial No. 538,788, filed October 5, 1955, and which is detonated by either a commercial blasting cap or a detonating fuse. It may also be advantageous to use, as the booster, a cartridge of dynamite, preferably of a diameter approximating that of the borehole.

In the practice of one embodiment of blasting method, a suitable booster charge, or dynamite primer, with detonating means therefor, is inserted into the borehole a distance sufficient that it can be covered by a fluent explosive charge of the invention. The explosive is then poured, or pumped, into the borehole onto the booster and the booster detonated to initiate detonation of the explosive charge. This method embodiment is advantageously applied to water-containing boreholes, the density of the explosive composition being always of sufliciently high value to permit the explosive to gravitate through the water to its position for detonation. In this type of blast ing the booster charge can be at the bottom, top or at any convenient position in the column. It is often advantageous to use two or more suitably spaced in the column for greater reliability of detonation.

In accordance with another blasting procedure the explosive composition of the invention is packaged in bags which are slit just prior to placement in the borehole so as to permit at least a portion of the composition to move from the bag to completely fill the borehole cavity to the desired height. If desired, the explosive can be bagged as expandable intact packages, e.g., in plastic bags, which expand to fill the hole cavity to a given height as desired. Where a lower density of loading is desired, the charges may be lowered in bags or other containers to. give a columnar load. With compositions of a somewhat rubbery nature, it is preferable to remove the charge from the container and drop it down the hole. However, gravitation or pumping of the unpackaged explosive either as a pourable slurry or a fluent mass of greater consistency provides for an eflicient filling of the borehole cavity and is, therefore, often preferred. When pumping, or blowing, the slurry, it is preferred to run a hose to the bottom of the hole and pump the slurry in at the bottom so that it can build up in a solid column displacing the water and filling the hole.

The minimum density of the explosive compositions of the invention is greater than that of water. The preferred density range, grams per cc., of the compositions is in the order of from 1.2 to 1.7. Accordingly, in the practice of a preferred method embodiment of the invention, blasting is carried out in a water-containing borehole, by introducing a water-compatible explosive of the invention into the borehole and gravitating it through the water, in direct contact therewith toward the bottom of the hole, generally into operative relationship with a booster previously placed in the borehole, for detonating the said explosive, and then detonating the explosive.

There are two major variables which affect density of the composition, namely, water content and temperature of the ingredients during the mixing sequence. By regulating the mixing temperature, the degree of displacement of entrained air is controlled. Thus, by way of illustration, mixing of water with the solid ingredients can be conducted at a temperature, such that air entrainment among the solid granules is not completely driven from the resulting mass, in which case the density value is correspondingly low in accordance with the degree of residual air entrainment. However, by elevating the mixing temperature, the degree of air entrainment removal is greater due to solution of large proportions of oxidizing salt in the water. In any event, it is a matter of controlling admixing temperatures so as to fill the voids in the salt to the desired degree to attain the desired density. The temperature of the ingredients during the mixing sequence is generally regulated within the range of about 60 to 160 F., the total mixing period being no more than about 5 to 12 minutes, the period of agitation following addition of oxidizer salt ingredients and gel former to the water and the period of agitation following addition of smokeless powder each being in the order of from about one to six minutes, more often not exceeding about three minutes.

In accordance with another preparative procedure, a dense slurry can be conveniently mixed for use in a watercontaining borehole by first pouring the smokeless powder into the hole, followed by addition of the remaining ingredients, all in the above described proportions. If necessary, additional Water can be added to the borehole to supplement that already there. In this embodiment it is of very little, if any, advantage to utilize a thickening, or gel-forming, ingredient. Alternatively, the oxidizer salt can be added prior to addition of the smokeless powder or if desired, the two can be added simultaneously, separately or in admixture. It is important in any event that the solution of oxidizer salt that is formed be saturated and that stirring by any convenient method such as by an air stream is maintained throughout the mixing operation.

As illustrated with reference to Table I herein, guar gum in inhibited and cross-linked form as well as natural guar gum is advantageously utilized. By the term inhibited is meant that that particular guar gum contains an agent which prevents the guar gum from gelling immediately upon contact with the water, thus permitting the gum to disperse to a larger degree before gelation occurs, gelation of the natural gum being in many instances substantially instantaneous upon contact with the water. Exemplary inhibiting agents are hydrophobing materials particularly those capable of liberating borate ions, particularly sodium borate (borax). In order that the inhibiting action take place, a pH of about 7 to 8 is gener- 6 ally required subsequent to which the pH is adjusted to a lower value to permit hydration to take place say, to a pH of 56. It is necessary that the gel-forming agent be uniformly dispersed in the explosive composition mixture prior to gelation so as to preclude uneven distribution of gel with concomitant lump formation.

Although it is advantageous to, in lieu of use of inhibited guar gum, first uniformly mix the gelation agent, and particularly the mannogalactans, with the dry ingredients and then add the resulting dry mixture to the water to obtain uniformity of mixing, gelation takes place unduly quickly so that generally there is insufficient time for satisfactorily completing uniform distribution of the agent before gelation is under way.

Use of guar gum in inhibited form permits the necessary time for uniformity of mixing of all ingredients prior to appreciable gelation.

By the term cross-linked guar gum is meant a chemical cross-linking of the guar gum, with the cross-linking agent, in the gel, to improve the cohesiveness and viscosity. Cross-linking is provided by the presence of borate ion, cuprous ion and others, say at a pH in the order of from 6.5 up to 7.0-7.5.

The compositions containing guar gum in cross-linked state are not only improved in respect to cohesiveness but are also less adhesive to the extent that they can be handled without their adhering in rather large proportions to the equipment with which they are in contact including plastic bags in which they are often stored.

In use of inhibited guar gum, the inhibiting agent is preferably introduced as an integral part of the guar gum, i.e., as a component thereof. The amount of inhibitor is generally in the order of about 1 per cent of the total guar gum added. Use of guar gum with borax provides for delay in the gelation for a period of say, from about 1220 minutes, which time is sufficient for mixing and packaging to provide for the major portion of the gelation in the package.

When utilizing an inhibited guar gum, it is sometimes advantageous to also utilize a relatively small proportion of an uninhibited guar gum to permit some gelation to take place early in the mixing period to a degree sufficient to maintain the mixture ingredients uniformly distributed, i.e., without there being any settling. However, the bulk of the gelation in that event takes place subsequent to the inhibiting action.

In cross-linking guar gum, as a gel former, borax as the cross-linking agent, is added to the product mixture just prior to completion of the mixing to provide for packaging before any appreciable cross-linking takes place. The re sulting cross-linked product mixture is cohesive to the extent that is separates completely from the walls of the container in which it is stored so that it can be easily removed from the container for use. The explosive compositions containing guar gum, and in which the guar gum is not cross-linked, are less cohesive and adhere to the walls of the container in which they are stored, to the extent that removal from the bag, e.g., a polyethylene bag, is accomplished with less ease than when the gum has been cross-linked as described. The pH is important in obtaining the cross-linking and should be in the order of from about 6.57 .5. Inasmuch as pH of the oxidizer salt solution is generally on the acid side, it is important that a suitable alkaline agent such as sodium bicarbonate, sodium hydroxide, ammonium hydroxide, disodium phosphate, diammonium phosphate, ethanolamine and the like, be added, under such conditions, prior to addition of the cross-linking agent to provide for the requisite pH. If the borax is added to the mixture prior to addition of the oxidizer salt, the guar gum will not disperse or gel, and the result will be a thin, ungelled mixture which will not cross-link upon aging. For this reason the borax dissolved in a small amount of Water is added just before the mixing is completed, and requires in the order of about 15 7 minutes before cross-linking is initiated, the amount of borax added being in the order of from about 0.8 to about 2 weight percent of the guar gum present.

Temperature during the mixing procedure, utilizing borax, is generally regulated to provide a final product at about 60 F. When the dry ingredients are added to the water ingredient and ammonium nitrate is the oxidizer ingredient or a component thereof, the temperature of the water is initially high to compensate for the cooling effect concomitant with the negative heat of solution of the ammonium nitrate in water, say an initial temperature of 100 to 120 F. depending on the concentration of the ammonium nitrate relative to other oxidizer salt ingredients. However, saturated ammonium nitrate solution at the predetermined product temperature, say 60 F. as above described, can be utilized. It is desirable to maintain the final mixture at a temperature at about 60 F. and higher inasmuch as when it warms up from a lower temperature, there may be some variance in product consistency.

In accordance with one mixing sequence in the formation of a composition containing guar gum cross-linked in the gel, the water ingredient, except for a small portion for dissolving borax as described hereinafter, is added to the mixer at a temperature to provide for a final product mixture at 60 F. or higher. An uninhibited guar gum is admixed with a portion of the oxidizer salt, say about 10-30 percent of the total oxidizer salt, and the resulting admixture added to the water. Agitation of the resulting water-oxidizer salt admixture is maintained for a short period, e.g., about a minute. If ammonium nitrate and an additional, or supplemental, oxidizer salt, for example, sodium nitrate, is utilized in the formulation, the guar gum can be mixed with the supplemental salt and added prior to the addition of the ammonium nitrate. Following the approximately one-minute agitation, the remainder of the oxidizer salt is added to the mixer followed by another brief period of agitation, say about 2 minutes. A suitable alkaline agent, say sodium bicarbonate, is then added to the resulting oxidizer salt-water-guar gum mixture with a portion, or all, of the smokeless powder ingredient, say about 10 to 40 percent of the total smokeless powder to be added, with subsequent brief agitation, say for 1-2 minutes, followed by addition of the remainder of the smokeless powder and subsequent agitation for a short time, say 1-2 minutes, or until the gelation is visibly under way. At this point of the sequence, borax in water solution, formed as above described, is added to the product mixture with a brief period of subsequent agitation, say about 1 minute followed by discharge of the product for storage. The consistency of the composition is such that it can be loaded by gravity for about -20 minutes before enough cross-linking occurs to make packaging difiicult. The above procedure can be altered by introducing the total guar gum (uninhibited) and oxidizer salt ingredient, in admixture, into the total water ingredient (except for that water required for the borax ingredient added subsequently) maintained at a temperature sufirciently high as to compensate for negative heat of solution of any ammonium nitrate present and to provide a resulting product at a temperature not below about 60 F., admixing total smokeless powder and alkaline agent, e.g., sodium bicarbonate, into the water-guar gumoxidizer salt mixture, and then adding the borax ingredient in solution with the remaining portion of water ingredient, there being a brief period of agitation following each additional step, e.g., 1-6 minutes.

In accordance with the preferred sequence in the manufacture of compositions that do not contain the guar gum cross-linked in the gel, the water ingredient is placed in the mixer at a temperature to compensate for negative heat of solution of ammonium nitrate as all or part of the oxidizer salt, and the guar gum is then mixed with a portion of the oxidizer salt and added to the water with subsequent agitation for about a minute, after which the remainder of the oxidizer salt is added to the mixture with subsequent agitation for 2-3 minutes. The smokeless powder ingredient is then added with subsequent agitation for 2-3 minutes or until the mixture begins to thicken from gel formation. The composition mixture is then ready for loading. In accordance with this procedure both uninhibited and inhibited guar gum is used as described above so as to delay the greater part of the gel formation. When utilizing the above procedure, employing ammonium nitrate and a supplemental oxidizer salt such as sodium nitrate, the guar gum can be added with the supplemental salt and then add-ed to the Water with a brief subsequent agitation, e.g., about 1 to 2 minutes. Thereafter the ammonium nitrate is added with subsequent stirring followed by the addition of the smokeless powder and subsequent brief agitation, e.g., from 2-3 minutes, and packaging.

It is also Within the scope of the invention to utilize a guar gum initially containing an inhibiting agent (e.g., borax) and to adjust the pH of the resulting product mixture to about 7 just prior to packaging to cause cross-linking of the guar gum in the gel. Thus, in one embodiment utilizing ammonium nitrate as the oxidizer salt ingredient, or a portion thereof, the inhibited guar gum is admixed with about 10-20% of the dry ammonium nitrate and fed to the water followed by addition of the remainder of the ammonium nitrate with agitation period of 5-7 minutes running from the time of addition of the guar gum. The smokeless powder is then admixed with an amount of sodium bicarbonate sufiicient to provide a resulting pH of about 7 to the composition mixture. After a short agitation period, say about 2 minutes, the composition is packaged. The formulation, containing crosslinked guar gum, and prepared in this manner, is particularly preferred for packaging in polyethylene bags in view of its excellent water resistance and the ease with which it separates from the bag walls when unloaded.

The preferred sequences above described which utilize ammonium nitrate as all or part of the oxidizer salt, are particularly advantageously carried out when the ammonium nitrate is in the form of prills. Sodium nitrate is particularly advantageously employed when the composition is to be utilized at temperatures below about 40 F. Urea can also be employed as a freezing point lowering ingredient.

The explosive compositions of the invention may, if desired, be formed at the blasting site, which permits handling and shipping the oxidizing salt ingredient as such without need for the precautions required when the sensitizer is present. However, the compositions are insensitive to shock and are relatively safe to transport.

The explosives of the invention exhibit markedly high ability to maintain and propagate sensitiveness under high pressures and can be utilized under waterheads in the order of p.s.i. and higher.

The sensitivity of the explosive compositions is such that they can be advantageously used with delay firing under water without premature propagation from one charge to another. In underwater blasting of trenches, etc., it is frequently desirable to use delay or short period delay blasting in which successive charges are tired at intervals of 25-50 milliseconds, and it is important that the later charges be not set off prematurely by the shock from the charges which are fired first.

The following tabulation, Table I, is further illustrative of the explosive compositions of the invention (all shown on Weight percent basis), being particularly illustrative of the fiuent and density properties in each case as well as various ranges of ingredient proportions, ingredient particle size, choice of ingredients, detonation characteristics, and the like.

TABLE I [All compositions shown on basis of weight percent] Ammonium Nitrate Sodium Nitrate 11 Calcium Nitrate Ca(Na):.4 B10. is onium Perchlorate.

gagier C b thl o um ar oxyme cellulose. y Guar Gum:

Uninhihitnfl Inhibited and Crosslinked. Inh

ibite Sodium Bicarb n pH Smokeless Powder Double Base Single Base Density, grams/cc Detonation Rate, M/sec.:

1% pipe 3 pipe- 4" cartrid e 5" cartridge (unconfine Grams Detonator B Oxygen Balance 15 Consistency at 80 132 Beaker Test Slump Test Ammonium Nitrate Sodium Nitrate Calcium Nitrate C&(NO3)3.4 HIgO.

onium Perchlorate. 13 Water Sodium Carboxymethylcellulose. i Guar Gum:

Uninhibited Inhibited and Crosslinked Inhibited.

Sodium Bicarbonate Smokeless Powder Double Base Single Base Density, grams/cc Detonation Rate, M/sec.:

5" cartridge (unconfined) Grams Detonator 8 Oxygen Balance 15 Consistency at 152 Beaker Test Slump Test Ammonium Nitrate Sodium Nitrate Calcium Nitrate onium Perchlorate.

Water Sodium Carboxyrnethylcellulose. Guar Gum:

Uninhibited Inhibited and Crosslinked Inhibited. Sodium Bicarbonate pH Smokeless Powder Double Base Single Base Density, grams/cc- Detonation Rate, M/sec.:

4' cartridge 5' cartridge (unconfined) Grams Detonator 8 Oxygen Balance Consistency at 80 F Thin, with some separation in normal storage.

N0 separation in normal storage.

Thicl r and pasty immediately upon mixing.

Pourable. Some separation after storage.

Slump Test Footnotes at end of table.

+2.0. Pourable. N0

separation after 1 month storage.

2 inches. 55 seconds.

TABLE IContinued Ammonium Nitrate Sodium Nitrate Calcium Nitrate C8.(NO3)2.4H2O Ammonium Perchlorate In Water Sodium Carboxymethylcellulose 2 Guar Gum:

Uninhibited Inhibitgd and Cross- Sodium Bicarbonate Smokeless Powder: 11

Double Base Single Base Density, grams/cc Detonation Rate, Mlsec:

p p 3 pe- 4" cartridge 5' cartridge (unconfined) Grarns Detonator 3 Oxygen Balance Consistency at 80 F Beaker Test 0.4 Pourable.

Slight separation in normal storage.

Free flowing up to 15 min. Thereafter, thick and pasty.

Free flowing up to min. Thereafter, cross-linked and rubbery.

1% borax added (of guar gum) but cross-linking was not obtained.

(of guar gum) with good cross-linking.

Slump Test {2'inches.

78 seconds Adjusted pH to 7 to obtain crosslinked slurry.

1 inch.

26 minutes.

Ammonium Nitrate Sodium Nitrate Calcium Nitrate Ca(NO3)g.4I'I2O. Ammonium Perchlorate.

Water Sodium Carboxyrnethylcellulose. Guar Gum:

Uninhibited Inhibited and Crosslinked. Inhibited Sodium Bicarbonate pH Smokeless Powder D ouble Ba e Single B ase Density, grams/cc Detonation Rate, M/sec.:

5 cartridge (uncon:

fined). Grams Detonator Oxygen Balance 15 +2 Consistency at F Beaker Test Slump Te 'r See footnote 14.

Ammonium Nitrate Sodium Nitrate Calcium Nitrate CEJ.(NO3)2.4HO.1B Ammonium Perchlorate. Water Sodium C cellulose. Guar Gum:

Uninhibited Inhibited and Crosslinked.

Inhibited S%Idium Bicarbonatep Smokeless Powder Single B ase Density, grams/cc..- Detonation Rate, M/sec.

1%pipe Grams Detonator 8 Oxygen Balance 15 5 cartridge (uncon- 1 Substantially all through 40-mesh screen, and substantially all on 100-mesh screen. Density=.90 to 1.0 gram per cc.Examples 1-13, 19, 22-29, 31, 38-42; substantially all through 12-mesh screen and substantially all on oo-mesh screenExamples 14-18, 20, 32; prills, bulk density 0.75 gram per cc.-Examples 21, 34-37, 41, 42; prills, bulk density 0.9 grams per cc.-Examples 30 and 33.

Granular varying from fine to coarse.

2 Fine ground high viscosity grade.

3 Wt. percent, Nitrocellulose 77, Nitroglycerin 20, salts and stabilizer 3. Grain size-0.045 x 0.034. One perforation, hole diameter 0.0043. Medium grade (particle size). Particle density=1.65 g./cc. Particle weight=0.0008 gram.

4 Wt. percent, Nitrocellulose 90.2, DNT oil 8, salts and stabilizer 1.8. Grain size=0.058 x 0.033 One perforation, hole diameter 0.0094 Medium" grade (particle size). Particle density=1.60 g./cc. weight=0.001 gram.

5 Wt. percent, Nitrocellulose 76.5, Nitroglycerin 19.5, salts and stabilizer 4.0. Grain size=0.43" x 0.25. One perforation, hole diameter 0.058. Coarse grade (particle size). Particle density=1.65 g./cc. Particle weight=0.56 gram.

5 Wt. percent, Nitrocellulose 87, salts and stabilizers 3.0, DNT oil 10.

Screen, 1.2% on mesh, 13% on mesh, 36% on mesh, 25% on 100 mesh, 24% through 100 mesh. Fine grade (particle size). Bulk density=0.80 gm./cc., Particle density=1.59 gJcc.

7 Wt. percent, Nitrocellulose 98, salts and stabilizers 2. Grain s1ze= 0.53 x 0.23". Coarse grade (particle size). Particle density=l.67

Product densities set forth in the above tabulation and Table 11 herein were determined by pouring a known weight of the fluent composition into a cylinder and measuringthe' volume, followed by calculation of the density in 'the usual manner. The detonation rate in each instance was determined by pouring the test charge into an iron pipe of diameter designated which is to give a degree of confinement comparable to that of drill holes used in commercial blasting. A PETN booster was "placed at one end of the pipe and initiated by a com- TABLE ICont1nued Consistency at F Pourable Pourable 1% borax aided 1% borax added Pourable. No Pourable. N o (of guar gum) (of guar gum) crosslinking (a cross-linking Free flowing up Free flowing up preferred (also a preto 25 minutes. to 25 minutes. pumpable [erred pump- Thereafter, Thereafter, composition.) able cross-linked cross-linked composition.) and rubbery. and rubbery.

Beaker Test- Slump Test "Ammonium Nitrate 58.1. 16. 5 19.1 Sodium Nitrate 42.0 23.4- 19.1

Calcium Nitrate 47.5-

CB.(NO3)2-4H2O.

onium Perchlo- 50.1

. rate.

Water 16.0- 11.0- 16.0- 16.9 27.4 20.0.

Sodium Carboxymethylcellulose.

Guar Gum:

Uninhibited 0.5 0.5. Inhibited and Crosa 0.7

linked. Inhibited 1.0. 1.0 1.0. 1.0. 1.0

Sodium Bicarbonate (7).2 0.2 0.2

Smokeless Powder:

Double Base Single Base 25.0 B 40.5 41.0 9 32.0 9 31.0 9 40.1 Density, grams/cc 1.54- 1.40 1.43 1.42. 1.45. Detonation Rate, M/sec.:

3' pipe 6,060 Shot. Shot- 4' cartridge- 4,880. 5,400.

5' cartridge (uncon- Grams Detonator 474 474 474 160 160.

Consistency at 80 F Free flowing up Pourable Pourable Pasty Pourable. Crosslinked.

to about 20 Slightly cross- Somewhat minutes. linked. rubbery. Thereafter, cross-linked and rubbery.

Beaker Test Slump Test Seven perforations, each hole diameter 0.022". Particle weight grams.

8 80 percent PETN* dispersed in 20 percent solid polyester resin.

9 Wt. percent, Nitrocellulose 97.7, salts and stabilizer 2.3. Grain size 0.095 x 0.039. Single perforation.

Same as footnote (9) exce t ground-30 mesh, 43.8%; 50 mesh, 10.5%; 80 mesh, 2.8%; mesh, 1.6 and 200 mesh, 0%.

11 Nitrogen content of nitrocellulose component in all cases was above 12 percent. Nitrocellulose colloided in all instances.

12 Composition (1) of Tests 1-11 (room temperature) were fluent and were of somewhat pasty consistency; (2) of Tests 12-13 were easily pourable with some separation of components upon prolonged standing.

13 Same as footnote (9) except ground to Fine grade size.

14 Slump test:

Particle OSeco'nds Slump Inches 0 15 Grams oxygen excess or deficient per 100 grams of compositron.

*Examples 1-13, 16, 27, 29, 41 and 42; 98 percent RDX/TNT (60/40), 2 percent wax-Examples 30, 32, 38-40. All examples report grams detonator per se. PETN aloneExamples 14, 15, 17, 25, 26 and 31.

stance was packed in exactly the same manner as was done for the density measurement.

Particularly illustrative of the function of the smoke- 'less powder component as a sensitizer, in the practice of the invention, are two ammonium nitrate-water mixtures containing 95.5 and 93.7 percent ammonium nitrate and 4.5 and 6.3 percent respectively, of water, each of which 7 failed to detonate in response to det-ona-ting action of a 173 gram boost-er charge of 80 percent PETN dispersed in a solid polyester resin. At higher water contents the sensitivity of the aqueous ammonium nitrate compositions is even less.

Sensitivity of the compositions of the invention is affected by particle size of the smokeless powder sensitizer component. Thus, the finer the sensitizer particle size, the lower the content of sensitizer component that is necessary for causing detonation. With increased 15 water content of the composition, the sensitivity of the composition is lowered so that in such instances a sensitizer of particle size finer than is required for lower water content compositions is preferred.

16 content of at least about 11.3 weight percent, generally in the range of from about 1213.5 percent, and being in colloided form. As is well known, the single base .powder contains colloided nitrocellulose as the chief com- The relation of particle size of sensitizer to the component, say in the order of from about 85 to 99 Weight position is further illustrated with reference to saturated percent and the double base powder contains the same ammonium nitrate solutions. Thus, the smokeless powcol-loided nitrocellulose component but together with der sensitizer of footnote 6 of Table I will sensitize a nitroglycerin or an equivalent liquid explosive nitric saturated ammonium nitrate solution at a smokeless powester. Double base powders contain generally at least der content as low as about 8 to 9 percent. On the other 10 one-third colloided nitrocellulose and substantially the hand, employing the coarse smokeless powder of Table I, remainder nitroglycerin, with, of course, the usual supfootnote 7, in the saturated ammonium nitrate solution, plemental ingredients. Triple base powders contain the smokeless powder content must be about 20 percent nitroguanidine in addition to the colloided nitrocellulose, in order to effect detonation. The fine smokeless powder and nitroglycerin, in proportions generally at least about of footnote 6 of Table I sensitizes ammonium nitrate 40 to 50 percent nitroguanidine and substantially as the solutions containing up to about 40-45 percent water, remainder colloided nitrocellulose and nitroglycerin, the whereas the coarse smokeless powder sensitizer of footlatter two being in any suitable relative proportions, for note 7 does not sensitize the compositions when more example, 1:1, to 4:1 of nitrocellulose to nitroglycerin. than 15 percent water is present. Minor amounts of supplemental ingredients are utilized The ratio of total oxidizing salt to smokeless powder in these powders, particularly stabilizing agents, gelation component is variable over a rather wide range, as above agents, oxidizer salts, in some instances DNT oil and the described, being in the order of from about 0.5:1 to like, all as well known in the art. Smokeless powder is 8:1 or higher, generally up to about 6:1, dependent particmanufactured in the form of small flakes, strips, pellets, ularly upon the content of smokeless powder and water, granules and cylindrical grains, the latter being generand diameter of the blasting charge, all of which affect senally perforated. sitivity to detonation. Various procedures have been utilized in the manufac- Table II is illustrative of variance in density among ture of this type of smokeless powder. Thus, in the usual but compositions, the water content ranging from 11.3 solvent process, which generally utilizes a water-wet to 50 percent with change in gel former (CMC) content nitrocellulose as raw material, the water in the nitro- *of from 2.5 to 5.0 percent, two of the compositions concellulose is first replaced, for example, by treatment with taining no gel-forming agent. Table II further illustrates ethyl alcohol. A colloiding solvent such as ether or the dilution effect of added amount of Water (Example acetone is then added to the dehydrated alcohol-wet 46), i.e., subsequent to filling all the voids so that at nitrocellulose along with the additional ingredients and that point, the water, by its own density, contributes to a a doughy mass is formed in a suitable mixer such as a lowering of the density value. Sigma blade mixer. This dough is then formed into TABLE II Ammonium Nitrate 36.25 33.5 28.0 22.5 73.7 60.7 Water 25.0 30.0 40.0 50.0 11.3 24.3 Sodium Carboxyme 2. 5 3.0 4. 0 5. 0 Smokeless Powder 36. 25 33. 5 28. 0 22. 5 5. 0 15. 0 Density, gJcc 1.27 1. 27 1. 23 1. 14 1.. 6 1.4 Detonation Rate,M/sec 4 5,590 5,320 5, 240 Failed 5 320 4,460 Grams Detonator 5 160 16 6 4 160 160 1 Substantially-all on -mesh screen, and substantially all through 100-mesh screen.

Density=.90 to 1.0 gram per cc.

1 Fine ground high viscosity grade.

Fine grade (particle size). Bulk density=0.80 g./cc.

4 3-inch pipe.

Screen, 1.2%

All rates measured at least Six charge diameters from the detonators.

5 80 percent PETN dispersed in 20 percent solid polyester resin. Grams PETN per se reported.

5 Example 47, ingredients admixed at 60 0.; Example 48, ingredients admixed at 20 0.

Supplemental oxidizer salts can be utilized in any desired proportion with ammonium nitrate, although they are preferably utilized in a Weight ratio thereto less than 1:1 generally in a minimum weight ratio of ammonium nitrate to supplemental oxidizing salt of about 1.25:1 to impart increased density to the overall composition and to lower the freezing point. Sodium nitrate in a Weight ratio to ammonium nitrate of about 0.121 to about 0.8:1 is particularly advantageously utilized in this manner.

Oxygen balance of the compositions of the invention is nearly zero in many instances. This means that we can use a lesser amount of supplemental salt with a correspondingly larger proportion of ammonium nitrate than would be the case if the oxygen balance of the sensitizing ingredient were more negative. Accordingly, it is unnecessary in most instances to add a supplemental oxidizer salt for purpose of adjusting oxygen balance which means that, in any instance, correspondingly larger proportions of ammonium nitrate can be utilized with accompanying increased strength of the explosive.

By the term smokeless powder it is meant herein the Well known colliloided nitrocellulose powders, the nitrocellulose in all events being characterized by a nitrogen green grains, usually by extrusion into cords followed by cutting the cords to the desired length. The green grains are then subjected to solvent removal'steps, including vaporization, water leaching and drying.

Exemplary of the smokeless powder formulations contemplated in the practice of the invention are:

Weight Percent Single Base Double Base Triple Base Nitr0ce1lul0se 99. 0 Nitroguanidine Dibutyl phthalate. Potassium Sulfate Ethyl Centralite. Cry0lite* As will be evident to those skilled in the art, various modifications can be made or followed, in the light of 17 the foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure or from the scope of the claims.

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

1. As a water-compatible, water-soluble salt type explosive, on a weight basis, a uniform mixture of (a) from about 20 -to about 80 percent of an inorganic oxidizer salt, (b) from about 8 to about 70 percent of a colloided nitrocellulose smokeless powder, in the form of particles, selected from the group consisting of single base, double base and triple base smokeless powders, and the said nitrocellulose having a nitrogen content of at least 11.3 percent and (c) from about to about 45 percent water; and said explosive being fluent and insensitive to detonating action of .a commercial No. 8 blasting cap and having a density greater than that of water.

2. An explosive composition of claim 1 containing from 0.2 to 5 Weight percent of a gel-forming agent selected from the group consisting of sodium carboxymethylcellulose, a mannogalactan, methyl cellulose and a water-swellable starch, for gelation of said water, and containing said water and said agent as gelation product so produced.

3. An explosive composition of claim 1 wheerin said density is within the range of from 1.2 to 1.7 grams per cc.

4. A water-compatible ammonium nitrate explosive of claim 1 wherein said inorganic oxidizer salt comprises ammonium nitrate.

5. An explosive composition of claim 4 containing from to 25 percent water and up to 50 percent of said smokeless powder. v

6. An explosive composition of claim 4 containing from 0.2 to 3 weight percent of a gel-forming agent selected from the group consisting of sodium carboxymethylcellulose, a mannogalactan, methyl cellulose and a water-swellable starch, for gelation of said water, and containing said water and said agent as gelation product so produced.

7. An explosive composition of claim 6 containing from 10 to 25 percent water and sodium carboxylmethyl cellulose as said gel-forming agent.

8. An explosive composition of claim 6 containing from 10 to 25 percent water and a guar gum as said gel-forming agent.

9. An explosive composition of claim 8 containing borax and wherein said guar gum is cross-linked with said borax in said gel.

10. As a water-compatible ammonium nitrate explosive, on a weight basis, a uniform mixture of (a) from about 45 to about 75 percent of an inorganic oxidizer salt comprising ammonium nitrate, (b) from about to about 50 percent of a colloided nitrocellulose smoke-- less powder in the form of particles, and the said nitrocellulose having a nitrogen content of at least 11.3 percent, and selected from the group consisting of single base, double base and triple base smokeless powders and, (c) from about 10 to about 25 percent water, and (d) from about 0.2 to 3 percent of a guar gum as gel-forming agent for gelation of said water, and gelation product so produced; and said explosive being fluent and insensitive to detonating action of a commercial No. 8 blasting cap and having a density greater than that of water.

11. An explosive composition of claim 10 wherein said oxidizer salt is selected from the group consisting of 1) ammonium nitrate and (2) an admixture of ammonium nitrate and an inorganic salt selected from the group consisting of perchlorates and nitrates of alkali and alkaline earth metals.

12. An ammonium nitrate explosive of claim 10 containing an alkali metal nitrate as a portion of said oxidizer salt.

13. An explosive composition of claim 10 containing borax and whereinsaid guar gum is cross-linked with said borax in said gel.

14. As a water-compatible, water-soluble salt type explosive, on a weight basis, a uniform mixture of (a) from about 20 to about percent of an inorganic oxidizer salt, (b) from about 8 to about 70 percent of a colloided nitrocellulose single base smokeless powder, in'the form of particles, containing from -99 percent nitrocellulose having a nitrogen content of at least 11.3 percent, and (c) from about 5 to about 45 percent Water; and said explosive being fluent and insensitive to detonating action of a commercial No. 8 blasting cap and having a density greater than that of water.

15. As a water-compatible, water-soluble salt type explosive, on a weight basis, a uniform mixture of (a) from about 20 to about 80 percent of an inorganic oxidizer salt, ('b) from about 8 to about 70 percent of a colloided nitrocellulose double base smokeless powder, in the form of particles, and the said nitrocellulose having a nitrogen content of at least 11.3 percent, and (c) from about 5 to about 45 percent water; and said explosive being fluent and insensitive to detonating action of a commercial No. 8 blasting cap and having a density greater than that of water.

16. A water-compatible, water-soluble salt type ex plosive, on a weight basis, comprising a uniform mixture of (a) from about 20 to about 80 percent of an inorganic oxidizer salt, (b) from about 8 to about 70 percent of a colloided nitrocellulose triple base smokeless powder, in the form of particles, containing at least 40 percent nitroguanidine and the said nitrocellulose having a nitrogen content of at least 11.3 percent, and (c) from about 5 to about 45 percent water; and said explosive being fluent and insensitive to detonating action of a commercial No. 8 blasting cap and having 'a density greater than that of Water. a

17. A water-compatible, water-soluble salt type explosive, .on a weight basis, comprising a uniform mixture of (a) from about 20 to about 80 percent of an inorganic oxidizer salt, (b) from about 8 to about 70 percent of a triple base colloided nitrocellulose smokeless powder, in the form of particles, containing at least 40 percent nitroguam'dine, and colloided nitrocellulose and nitroglycerin as substantially the remainder of said explosive mixture in relative proportions of nitrocellulose to nitroglycerin within the range of from 1:1 to 4:1, and the said nitrocellulose having a nitrogen content of at least 11.3 percent, and (c) from about 5 to about 45 percent water;

and said explosive being fluent and insensitive to detonating action of a commercial No. 8 blasting cap and having a density greater than that of water.

18. A composition of claim 17 wherein the nitroglycerin content of said explosive is 19.0 percent.

19. A water-compatible, water-soluble salt type explosive, on a weight basis, comprising a uniform mixture of (a) from about 20 to about 80 percent of an inorganic oxidizer salt, (b) from about 8 to about 70 percent of a double base colloided nitrocellulose smokeless in the form of particles, containing about 20 percent nitroglycerin and the said nitrocellulose having nitrogen content of at least 11.3 percent, and (c) from about 5 to about 45 percent water; and said explosive being fluent and insensitive to detonating action of a commercial No. 8 blasting cap and having a density greater than that of Water.

20. A water-compatible, water-soluble salt type explosive, on a weight basis, comprising a uniform mixture of (a) from about 20 to about 80 percent ofan inorganic oxidizer salt, (b) from about 8 to about 70 percent of a double base colloided nitrocellulose smokeless powder, in the form of particles, containing about 19.5 percent nitroglycerin, and the said nitrocellulose having a nitrogen content of at least 11.3 percent, and (c) from about 5 to about 45 percent water; and said explosive being fluent and insensitive to detonating action of a commercial No. 8 blasting cap and having a density greater than that of water.

21. A slurry type blasting composition consisting essentially of about 40 to 80 percent ammonium nitrate, about 10 to 50 percent of smokeless powder particles, and the balance substantially Water with a thickening quantity of guar gum.

22. A slurry-type blasting composition consisting essentially of about 40 to 80% ammonium nitrate, about 10 to 50% of smokeless powder particles, and the balance substantially water containing a thickening agent.

23. In the manufacture of a water-compatible explosive which contains, on a weight basis, from about 20 to about 80 percent of an inorganic oxidizer salt comprising ammonium nitrate, from about 8 to about 70 percent of a smokeless powder as a sensitizer, from about to about 45 percent water, and from 0.2 to 5 percent of guar gum as a gelation agent for forming a gel with said water, the improvement comprising maintaining a major portion of said water ingredient at a temperature described hereinafter, admixing said guar gum with a portion of said oxidizer salt and adding the resulting oxidizer salt-guar gum admixture to said water portion with subsequent agitation to uniformly distribute the said gum and oxidizer ingredients therein, admixing the remaining portion of said oxidizer salt with the said water oxidizer salt-guar gum admixture with subsequent agitation to uniformly distribute the newly added oxidizer salt therein, admixing a portion of said smokeless powder with an amount of an alkaline reacting agent selected from the group consisting of inorganic phosphates, bicarbonates and hydroxides, and lower alkanol amines described hereinafter and adding the resulting admixture to said oxidizer salt-water-guar gum admixture with subsequent agitation to uniformly distribute said smokeless powder and alkaline agent therein and then adding the remaining portion of said smokeless powder to the resulting alkaline agent-containing admixture with subsequent agitation to uniformly distribute the last said smokeless powder portion therein, admixing from 0.8 to 2 percent of borax, based on the weight of said guar gum, with the remaining portion of said water and adding the result ing water-borax mixture to the admixture containing the last said smokeless powder portion with subsequent agitation to uniformly distribute said borax therein, and then storing the resulting borax-containing mixture within a period of about 20 minutes from termination of the last said agitation, the said water temperature being up to about 120 P. so as to compensate for a sufiicient portion of the negative heat of solution of said ammonium nitrate in the said water to maintain the temperature of the oxidizer-containing admixture above a minimum of about 60 F. until after said borax is added thereto, and the said amount of alkaline agent being sufficient to impart a pH of from 6.5 to 7.5 to the resulting boraxcontaining mixture, whereby said guar gum during said storage cross-links with the borate ion in said gel to form a rubbery product.

24. A method of claim 23 wherein said oxidizer salt is an ammonium nitratesodium nitrate mixture and wherein said guar gum is added to said water in admixture with said sodium nitrate followed by addition of said ammonium nitrate as said remaining portion of said oxidizing salt.

25. A method of claim 23 wherein ammonium nitrate is the only oxidizing salt added to said water, and wherein the temperature of the first said water portion is above 120 F.

26. In the manufacture of a water-compatible explosive which contains, on a weight basis, from about 20 to about 80 percent of an inorganic oxidizer salt comprising ammonium nitrate, from about 8 to about 70 percent of a smokeless powder as a sensitizer, from about 5 to about 45 percent water, and from 0.2 to 5 percent of guar gum as a gelation agent for forming a gel with said water, the improvement comprising maintaining a major portion of said Water ingredient at a temperature described hereinafter, admixing said guar gum with said oxidizer salt and adding the resulting oxidizer salt-guar gum admixture to said water portion with subsequent agitation to uniformly distribute the said gum and oxidizer ingredients therein, admixing said smokeless powder with an amount of an alkaline reacting agent selected from the group consisting of inorganic phosphates, bicarbonates and hydroxides, and lower alkanol amines described hereinafter and adding the resulting admixture to said oxidizer salt water-guar gum admixture with subsequent agitation to uniformly distribute said smokeless powder and alkaline agent therein, admixing from 0.8 to 2 percent of borax, based on the weight of said guar gum with the remaining portion of said water and adding the resulting water-borax mixture to the smokeless powder-containing mixture formed as above described with subsequent agitation to uniformly distribute said borax therein, and then storing the resulting borax-containing mixture within a period of about 20 minutes from the last said agitation, the said water temperature being suificient to compensate for a up to about 120 F. so as portion of the negative heat of solution of said ammonium nitrate in the said water to maintain the temperature of the oxidizer-containing admixture above a minimum of about 60 F. until after said borax is added thereto, and the said amount of alkaline agent being suflicient to impart a pH of from 6.5 to 7.5 to the resulting borax-containing mixture, whereby said guar gum during said storage cross-links with the borate ion in said gel to form a rubbery product.

27. In the manufacture of a water-compatible explosive which contains, on a weight basis, from about 20 to about percent of an oxidizer salt comprising ammonium nitrate, from about 8 to about 70 percent of a smokeless powder as a sensitizer, from about 5 to about 45 percent water, and from 0.2 to 5 percent of guar gum as .a gelation agent for forming a gel with said water, the improvement comprising maintaining said water ingredient at a temperature described hereinafter, admixing a guar gum, containing an agent selected from the group consisting of boron ionand cuprous ion-yielding compounds described hereinafter, with said oxidizer salt and adding the resulting oxidizer salt-guar gum admixture to said water ingredient with subsequent agitation to uniformly distribute the said gum and oxidizer ingredients therein, admixing said smokeless powder with the said oxidizer salt water-guar gum admixture with subsequent agitation to uniformly distribute said smokeless powder therein and then storing the resulting smokeless powder-containing admixture within a period of about 20 minutes from the last said agitation, the said agent contained in said guar gum functioning to inhibit a substantial portion of the gelation of said gum with said water until subsequent to the said 20-minute period, the said water temperature being sufiicient to compensate for a sufficient portion of the negative heat of solution of said ammonium nitrate in the said water to maintain the temperature of the oxidizer-containing admixture above 60 F. until after storing the admixture as above described.

28. A method of claim 27 wherein said inhibiting agent promotes cross-linking of said guar gum with said water in the resulting gel at a pH above about 6.5, and wherein an alkaline reacting agent is added to the resulting smokeless powder-containing admixture prior to the expiration of said 20-minute period to raise the pH of the last said mixture to a value sufficiently high to facilitate said cross-linking.

29. A slurry-type blasting composition consisting essentially of about 40 to 80% ammonium nitrate, about 10 to 50% of smokeless powder particles, and the balance substantially Water containing a thickening quantity of a thickening agent. i

21 30. A slurry-type blasting composition consisting essentially of about 40 to 80% ammonium nitrate, about 10 to 50% of smokeless powder particles, and the balance substantially water containing a thickening agent in the amount of from about 0.2% to 2% 0f the composition.

References Cited by the Examiner UNITED STATES PATENTS 868,636 10/ 1907 Braunstein 527 1,820,568 8/1931 Jones 5218 X 2,358,384 9/1944 Davis 5211 2,365,170 12/1944 Bitting 5213 2,496,670 2/1950 Moe 260-209 2,768,073 10/1956 Davidson 5211 2,860,041 11/1958 Griffith et al 14958 2,867,172 1/1959 Hradel 5214 X 2,930,685 3/1960 Cook et a1. 5211 22 FOREIGN PATENTS 12/ 1875 Great Britain.

OTHER REFERENCES LEON D. ROSDOL, Primary Examiner.

CARL D. QUARFORTH, ROGER L. CAMPBELL,

OSCAR R. VERTIZ, Examiners.

15 B. R. PADGETT, A. D. AKERS, W. T. HOUGH,

Assistant Examiners.

Claims

1. AS A WATER-COMPATIBLE, WATER-SOLUBLE SALT TYPE EXPLOSIVE, ON A WEIGHT BASIS, A UNIFORM MIXTURE OF (A) FROM ABOUT 20 TO ABOUT 80 PERCENT OF AN INORGANIC OXIDIZER SALT, (B) FROM ABOUT 8 TO ABOUT 70 PERCENT OF A COLLOIDED NITROCELLULOSE SMOKELESS POWDER, IN THE FORM OF PATICLES, SELECTED FROM THE GROUP CONSISTING OF SINGLE BASE, DOUBLE BASE AND TRIPLE BASE SMOKELESS POWDERS, AND THE SAID NITROCELLULOSE HAVING A NITROGEN CONTENT OF AT LEAST 11.3 PERCENT AND (C) FROM ABOUT 5 TO ABOUT 45 PERCENT WATER; AND SAID EXPLOSIVE BEING FLUENT AND INSENSITIVE TO DETONATING ACTION OF A COMMERCIAL NO. 8 BLASTING CAP AND HAVING A DENSITY GREATER THAN THAT OF WATER.