US 3629021 A
Description (OCR text may contain errors)
United States Patent SLURRY EXPLOSIVE COMPOSITION CONTAINING NITROGEN-BASE SALT AND TNT, SMOKELESS POWDER OR COMPOSITION B 17 Claims, No Drawings U.S. Cl 149/50, 149/56, 149/57, 149/64, 149/65, 149/69, 149/92, 149/96, 149/98, 149/100, 149/105 Int. Cl C06b l/04  Field of Search 149/38, 39, 41,49, 50, 56,57, 63, 64, 65, 69, 98, 100, 92,105, 88, 96
 References Cited UNITED STATES PATENTS 3,401,067 9/1968 Fee et a1. 149/92 X 3,409,484 11/1968 Minnick 149/92 X 3,431,155 3/1969 Dunglinson et al. 149/92 X 3,471,346 10/1969 Lyerly 149/92 X Primary Examiner-Carl D. Quarforth Assistant Examiner-Stephen J. Lechert, .lr. AtI0rneyJames .l. Flynn ABSTRACT: A thickened water-bearing explosive comprising inorganic oxidizing salt, fuel, TNT, smokeless powder or Composition B and nitrogen-base salt.
SLURRY EXPLOSIVE COMPOSITION CONTAINING NITROGEN-BASE SALT AND TNT, SMOKELESS POWDER OR COMPOSITION B BACKGROUND OF THE INVENTION This invention relates to blasting agents and, more particularly, to water-bearing explosive compositions having excellent low-temperature properties and a high velocity of detonation.
Blasting agents of the type known as water-bearing or slurry explosives have gained considerable commercial acceptance in recent years. These water gels generally comprise an inorganic oxidizing salt, predominantly ammonium nitrate, a thickening agent for the liquid, a fuel and sensitizer. In order to have blasting agents sensitive enough to propagate detonation throughout the mass in confined columns, it usually has been necessary to incorporate therein substantial quantities of high explosive. The use of major amounts of high explosives in water-bearing explosives is disadvantageous because, amount other things, it adds considerably to the cost of the blasting agent. Furthermore, water-bearing slurry explosives are difficult to load in a borehole at low temperatures often encountered in mining areas. This difficulty arises because the explosive compositions thicken to such an extent at low temperatures that the gels become so viscous that they cannot be satisfactorily pumped or the water gels, if pumpable, tend to plug the borehole by bridging, which causes voids or interstices in the shot. Accordingly, there is a need for waterbearing slurry explosive compositions that have good low-temperature properties, e.g. easily pumpable, that are reliably sensitive and exhibit high velocities of detonation at low temperatures.
SUMMARY OF THE INVENTION This invention is directed to water-bearing explosives comprising an inorganic oxidizing salt component, a fuel component and a continuous thickened or gelled aqueous phase, the improvement which comprises including in said explosive sensitizer component consisting essentially of:
I. about from to 30 percent by weight of at least one of the group consisting of TNT, smokeless powder, Composition B and mixtures thereof, and at least 5 percent based on the total composition of at least one nitrogen-base salt of an inorganic oxidizing acid and a base selected from the group consisting of (a) acyclic nitrogen bases having no more than two hydrogen atoms bonded to the basic nitrogen and up to three carbon atoms per basic nitrogen, and (b) phenyl amines, said nitrogen-base salt having an oxygen balance more positive than about l50 percent, the weight percent of sensitizer l exceeding that of sensitizer 2, said composition having an unconfined relative velocity ratio at 40 F. of greater than l.l.
Quite surprisingly, the slurry explosive compositions of this invention have improved velocity of detonation with lower levels of TNT, smokeless powder or Composition B and nitrogen-base salt, said nitrogen-base salt increasing the sensitivity of the TNT, smokeless powder or Composition B. The blasting agents of this invention may be readily pumped to a borehole even at low temperatures and, due to the fluidity of the composition, they do not plug the borehole when loaded therein and they are reliably sensitive to conventional detonators or primers. The velocity of detonation of the water-bearing explosive can be expressed for comparative purposes as relative velocity. By relative velocity is meant the velocity of the present explosive composition over the velocity of the composition without a nitrogen-base salt, both velocities being determined at 40 F., unconfined, and at or about the critical diameter of the less sensitive composition utilizing the same type booster composition. The improvements in relative velocity, sensitivity and fluidity, brought about by the combination of TNT, smokeless powder or Composition B and nitrogen-base salt in the water-bearing blasting agent are particularly noticeable in blasting adverse conditions of low temperatures.
Oxidizing" and "fuel" components are used herein their conventional sense to refer to materials in the explosives which have positive and negative oxygen balances, respectively. Oxygen balances" as used herein refers to the percent excess or deficiency of oxygen required for complete combustion and is calculated as the molecular weight of oxygen required or given off in complete combustion divided by the molecular weight of the material in question. "Sensitizer" as employed herein refers to a material which when removed from an explosive in small, e.g., a few percent, incremental amounts substantially reduces the sensitivity of the explosive at its critical diameter at a given temperature of test.
DESCRIPTION OF PREFERRED EMBODIMENTS The nitrogen-base salts employed in this invention can be derived from inorganic bases such as hydrazine but preferably are derived from aliphatic amines and phenyl amines. Phen ylamines as used herein refers to compounds having one carbocyclic aromatic ring to which is bonded at least one, and preferably one or two, primary amino groups. Salts of primary, secondary and tertiary amines meeting the aforementioned requirements can be used. Although the base moiety can bear substituents other than carbon, hydrogen and the base nitrogen inert with the system, those consisting of carbon, hydrogen and the aforementioned basic nitrogen are preferred. Because of availability, low cost, ease of handling and manufacture and excellent explosive properties of the products of this invention made therefrom, salts of saturated aliphatic amines having up to three carbon atoms are preferred. The oxidizing acid moiety can be that of any of the strong inorganic oxidizing acids, preferably mineral acids, such as salts of nitric, nitrous, chloric and perchloric acids. Those acids having an oxygen balance of at least about +l0 percent are preferred. Nitrates are particularly preferred because of their ready availability and excellent sensitizing effect.
Representative salts which can be used in the sensitizing component include inorganic salts such as hydrazine nitrate, dinitrate and perchlorate; salts of aliphatic amines such as monomethylamine nitrate, nitrite, chlorate and perchlorate, ethylenediamine dinitrate and diperchlorate, dimethylamine nitrate, trimethylamine nitrate, ethylamine nitrate, propylamine nitrate, ethanolamine nitrate, guanidine nitrate and urea nitrate and salts of phenyl amines such as aniline nitrate, chlorate and perchlorate, p-chloroaniline nitrate and phenylenediamine dinitrate. The nitrogen-base salts particularly preferred are monomethylamine nitrate, trimethylamine nitrate, ethanolamine nitrate and ethylenediamine dinitrate because of their case of formulation of explosives therewith and the outstanding explosive properties including velocity, fluidity, sensitivity and strength of the resulting products. Mixtures of the aforementioned salts can be used as well as mixtures of one or more of such salts with other similar salts having an oxygen balance more negative than percent, for example, cyclohexylamine nitrate and diethylamine dinitrate. Normally, in such salt mixtures, the overall oxygen balance of the salt should be more positive than l50 percent.
The nitrogen-base salts can be incorporated in the explosive composition in substantially pure form or as a crude reaction mixture of the base substantially neutralized with the oxidizing acid, either formed separately in aqueous medium then blended with the remainder of the constituents of the explosive or formed in situ in the presence of one or more of such constituents. ln any event, at least 5 percent, and not more than about 50 percent, based on the total composition of nitrogen-base salt is incorporated in the blasting agent, preferably 5 to 20 percent.
It has further been found that the water-bearing explosive must contain about from l0 to- 30 percent, and preferably 8 to 25 percent, by weight of certain explosives, namely,
trinitrotoluene, smokeless powder, Composition B or mixtures thereof in order to obtain the overall beneficial effects mentioned herein. The TNT or Composition 8 can be incorporated in the slurry composition in any conventional form such as flake, pelleted or granular, and smokeless powder can be incorporated in the explosive composition alone or mixed with Composition B or TNT. In all cases, the weight percent of TNT, smokeless powder, Composition B or mixtures thereof used in a particular formulation exceeds that of the nitrogenbase salt.
The thickened water-bearing blasting agents of the present invention contain sufficient water to dissolve all or a portion of the inorganic oxidizing salt used in the composition to form a continuous aqueous phase. Generally, the amount of water employed in the composition is from about to 50 percent, preferably at least about to 25 percent. Any inorganic oxidizing salt conventionally used in thickened water-bearing slurry explosives can be employed in the present composition. Representative inorganic oxidizing salts include the nitrates, perchlorates and chlorates of ammonia, the alkali metals and the alkaline earth metals. The amount of oxidizing salt present can be from 10 to 90 percent, and is usually used in amounts of about from 40 to 90 percent, preferably less than about 75 percent. In general, for economic reasons, ease of handling and optimum explosive properties, compositions containing an oxidizing salt component of at least 65 percent by weight ammonium nitrate are preferred. Examples of other inorganic salts that can be used in the thickened slurry explosive composition of this invention are sodium nitrate, calcium nitrate, potassium nitrate, magnesium nitrate, sodium perchlorate, potassium perchlorate, ammonium perchlorate and magnesium perchlorate. The preferred auxiliary salt is sodium nitrate, used in lesser proportions with ammonium nitrate, preferably in amounts up to 25 percent of the oxidizing salt component.
The slurry explosives of the present invention contain any fuel conventionally used with water-bearing blasting agents. Preferably, carbonaceous or sulfurous, fuels are used in the blasting agent such as sulfur, coal and other forms of finely divided carbon, solid carbonaceous vegetable products such as sugar, corn starch, wood and paper pulp, various meals such as ivory nut meal, solid and liquid organic hydrocarbons such as fuel oils and powdered paraffin waxes, as well as mixtures of two or more of these fuels. Generally, the explosive composition contains up to about 20 percent, and usually about 2 to 10 percent, by weight of the total composition of a suitable fuel.
The water-bearing compositions of this invention usually contain 0.1 to 5 percent, and preferably from 0.] to 2 percent, thickener. Representative thickening agents that are used in the composition are those conventionally used in water-bearing explosives such as gum arabic, ghatti, karaya; seaweed colloid such as agar-agar, lrish moss, and the alginates; seed ex- 5 or more of the above thickening agents. Galactomannans such as guar gum and locust bean gum are preferred thickeners for the present slurry explosive compositions. The thickening agents, such as the galactomannans, can be a self-complexing or noncomplexing guar gum. For example, a self-complexing guar gum, e.g., EX-FC-SO and EX-FC-DP supplied by Stein- Hall Company, or a noncomplexing guar gum such as Stein- HalI-l-s Jaguar 100 in which no cross-linking agent is incorporated are especially and equally suitable. However, when a noncomplexing thickening agent is used such as a galactomannan small portions. e.g., about 2 to 8 percent by weight of the total thickening agent, of cross-linking agent such as borax or other cross-linking agents known in the art can be used. The cross-linking, or complexing, of the thickening agent markeclly strengthens the gel. The carbonaceous thickening agents serve the dual function of thickener and fuel for the explosive composition and can comprise all or part ofthe soluble fuel used and are included in the calculation of the requisite fuel values.
Other additives that can be, and preferably are, added to the water-bearing explosive composition to improve sensitivity, especially when used under low-temperature conditions, are gas-entrapping materials and crystal habit modifiers. Any gasentrapping material can be used in the explosive composition such as microballoons or bagasse. However, microballoons made of urea-formaldehyde or phenolformaldehyde are quite satisfactory for this purpose and especially glass microballoons. The amount of gas-entrapping material incorporated in the composition is usually about from 0.1 to 5 percent, and generally at least about 0.25 percent. Crystal habit modifiers that are surfactants of the type disclosed in U.S. Pat. No. 3,397,097 can also be incorporated in the compositions of the present invention. Surfactants, especially anionic surfactants, particularly higher alcohol sulfonic esters containing about eight to 18 carbon atoms are quite suitable, for example, sodium lauryl sulfate (Duponol") and sodium stearyl sulfate; aliphatic alcohol phosphates, e.g. sodium alkyl phosphates; aliphatic amide sulfonates, e.g. sodium stearyl amide methylethyl sulfonate; alkyl-aryl sulfonates, e.g., sodium dodecyl benzene sulfonate. The amount of crystal habit modifier, or surfactant, added to the explosive compositions usually is in the range of about 0.1 to 3 percent.
For a clearer understanding of the invention, the following specific examples are given. These examples are intended to be merely illustrative of the invention and are not to be considered limitations thereof. Parts and percentages are by weight unless otherwise indicated.
tracts such as locust bean, guar and quince seed gums; Mo et y amme fi r I l l d 8 A Table I Detonation results at 40 F.
Comp. Diameter Velocity EDAN DAN TAN EAN TNT SP B AN SN H 0 Coal Sulfur (inches) (IL/sec.)
1 Control. 2 No deton. i
ethylenediamine dinitrate as EDAN, trimethylamine nitrate as TAN, ethanolamine nitrate as EAN, dimethylamine nitrate as DAN, ammonium sulfate as AN, sodium nitrate as SN, trinitrotoluene as TNT, smokeless powder as SP and Composition B, Le. 50 percent TNT and 50 percent RDX, as Comp. B.
Water-bearing explosives of the composition shown in table 1 are prepared in a mixer from the materials listed by the following sequence of steps:
1. An aqueous solution of amine nitrate of 70-86 percent concentration, ammonium nitrate and water are combined, the mixture heated to 150 to 170 F., and the heated mixture transferred to a suitable mixing vessel. 2. Sodium lauryl sulfate, glass microballoons, coal, sulfur, TNT, smokeless powder or Composition B are then added to the mixer and the composition mixed to blend the ingredients.
3. A premixed combination of sodium nitrate and guar gum is added to the mixer and the composition mixed for about 4 to 8 minutes until thickening is observed.
4. Cross-linking agents are added (borax or potassium antimony tartrate); the composition is mixed until the cross-linking agents are uniformly incorporated, and the material packaged in polyethylene tubing.
In addition to the ingredients listed, the compositions also contain, per hundred pound weight, 0.7-0.9 lb. of guar gum. Examples 7 and 8-210 contained 0.3 percent microballoons; examples 3 to 6, 8, 12 and 17-19 contained 0.3 percent sodium lauryl sulfate, and examples 7, 13-16 and 20 contained 1 percent sodium lauryl sulfate.
The samples of the explosive composition packaged in polyethylene tubing were initiated with a high-density cast primer which in turn was initiated with Primacord. The relative velocities of the composition were ascertained by determining the velocity of the composition with and without amine nitrate, unconfined, at 40 F. at or about the critical diameter of the less sensitive composition. In all instances, the relative velocity ratio of the composition was greater than 1.1. The densities of the compositions were between about 1.3-1.4 g./cc.
1. 1n water-bearing explosives comprising inorganic oxidizing salt component, fuel component and a continuous thickened or gelled aqueous phase, the improvement which comprises including in said explosive a sensitizer component consisting essentially of:
1. about from to 30 percent by weight of at least one of the group consisting of trinitrotoluene, smokeless powder, and a mixture of about 50 percent trinitrotoluene and about 50 percent cyclotrimethylene trinitramine. and 2. at least 5 percent based on the total composition of at least one nitrogen-base salt of an inorganic oxidizing acid and a base selected from the group consisting of (a) acyclic nitrogen bases having no more than two hydrogen atoms bonded to the basic nitrogen and up to three carbon atoms per basic nitrogen, and (b) phenyl amines, said nitrogen-base salt having an oxygen balance more positive than about percent. the weight percent of sensitizer l exceeding that of sensitizer 2, said compositions having a relative velocity ratio at 40 F. of greater than about 1.1.
2. The product of claim 1 wherein sensitizer component 1 is trinitrotoluene.
3. The product of claim 2 wherein sensitizer component 2 is ethylenediamine dinitrate.
4. The product of claim 3 containing 8 to 25 percent trinitrotolunene, 5 to 20 percent ethylenediamine dinitrate and at least 10 percent water.
5. The product of claim 2 wherein sensitizer component 2 is monomethylamine nitrate.
6. The product of claim 5 containing 8 to 25 percent trinitrotoluene, 5 to 20 percent monomethylamine nitrate and at least 10 percent water,
. The product of claim 6 wherein the inorganic oxidizing salt is ammonium nitrate or sodium nitrate or mixtures thereof.
8. The product of claim 7 containing air-entrapping materia1.
9. The product of claim 7 containing a crystal habit modifier, said modifier being a surfactant.
10. The product of claim 2 wherein sensitizer component 2 is ethanolamine nitrate.
11. The product of claim 10 containing 8 to 25 percent trinitrotoluene, 5 to 20 percent ethanolamlne nitrate and at least 10 percent water.
12. The product of claim 1 wherein sensitizer component 2 is monomethylamine nitrate.
13. The product of claim 1 wherein sensitizer component 2 is dimethylamine nitrate.
14. The product of claim 1 wherein sensitizer component 2 is ethylenediamine dinitrate.
15. The product of claim 1 wherein sensitizer component 2 is ethanolamine nitrate.
16. The product of claim 1 wherein sensitizer component 1 is a mixture of about 50 percent trinitrotoluene and about 50 percent cyclotrimethylene trinitramine.
17. The product of claim 1 wherein sensitizer component 1 is smokeless powder.
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