US3190777A - Fluidizing agents for water-bearing explosive compositions - Google Patents

Description

United States Patent This invention is concerned with water-bearing explosive compositions. More particularly, this invention is concerned with Water-bearing explosive compositions which are suitable for use at relatively low temperatures.

In recent years considerable interest has developed in the use of water-bearing explosive compositions for blasting operations. The presence of substantial amounts of water has been recognized as being beneficial in certain explosive compositions rich in ammonium nitrate, such as those described, for example, in US. Patent 2,930,685. Water-bearing explosive compositions can include substantial amounts of a self-explosive such a coarse granular TNT, may require a stronger primer than a conventional blasting cap, and may detonate completely only if the columns of explosive are of relatively large cross section and are strongly confined, as is true of compositions described in the aforementioned United States patent. On the other hand, water-bearing explosive compositions can be entirely free of self-explosive ingredients. In spite of the absence of a self-explosive, water-bearing compositions such as those described in U.S. Patent 2,836,484 are cap-sensitive high explosives which will detonate completely through long columns of relatively small diameter. Thus, a wide range of explosive properties can be found in water-bearing blasting agents.

Generally, the water-bearing blasting agents comprise an aqueous solution or slurry of inorganic oxidizing salts mixed with organic or metallic fuels and sensitizing agents which also can act as fuels.

Explosive compositions such as those described above are el'lective blasting agents and have come into increasing prominence because of their safety characteristics and economy, both in manufacture and use. However, generally speaking, such compositions are not suitable for use in wet boreholes since the water present in the borehole rapidly dilutes the explosive composition and leaches out both the dissolved and the undissolved, but watersoluble, oxiding salts thus leading to changes in composition which result in losses in explosive power or even in failures to detonate. In addition, even in dry boreholes segregation of components can take place under certain conditions so that solid components separate into layers above or below the aqueous salt solutions to the extent that gross inhomogeneity occurs, again leading to loss of strength and failure to propagate. The problems of segregation and classification of ingredients of the explosive composition are aggravated if the explosive composition is dropped or poured into water even from a short distance above the surface of the water.

The aforementioned difllculties have been overcome to a large extent by the incorporation of gelling agents such as guar gum, locust bean gum, powdered psyllium seed, and the like, either alone or in combination with cross- 3,19%,77? Patented June 22, 1965 linking agents which further enhance the thickening action of the hydrocolloid. Gelled or partially gelled compositions of superior properties are known in the explosives art, for example, as described in Canadian Patent No. olllitlti and US. Patent No. 3,972,509. The fluidity of thickened compositions is adjustable over a fairly wide range, depending upon the composition of the blasting agent, the kind and amount of thickening agent, the presence of erosslinlaing agents, the temperature of the composition, and perhaps other factors. Thus, compositions can be thickened only to the extent necessary to prevent segregation of the components of the mixture, while maintaining a sufficient degree of fluidity that the mixture easily can be pumped into containers or boreholes. Compositions more highly thickened can be extruded into cartridges or other suitable containers. In all instances, however, the advantages of the thickened blasting compositions are retained, viz, safety and ease of handling. resistance to leaching by water, absence of segregation of ingredients, and ability to fill or substantially fill irregularly shaped boreholes. Even in containers, the thickened explosive compositions will tend to fill or substantially fill the borehole if the container is sufficiently flexible, as when made of a thin, waterresistive film such as polyethylene, polyvinyl chloride, and the like. The more viscous compositions can even be loaded in upward-slanting or in overhead boreholes since the compositions have suflicicnt resistance-to-fiow to hold a position after being so placed by pumping, extruding, 0r tamping into the borehole.

The advantages of all of the aforementioned types of Water-bearing explosive compositions are manifest, but any changes in conditions which result in a loss of their ability to flow or deform greatly degrade or even destroy the utility of such explosive compositions. One of the most common causes of loss of fluidity is a lowering of the temperature during storage and during use of water- 'ocaring explosive compositions. In many parts of the world where blasting operations are carried on, temperatures seasonally or even during a large part of the year are well below the freezing point of water, and even Well below 0 F. The water-bearing explosive compositions may not lose their fluid characteristics at the freezing point of Water or even at temperatures substantially below 32 l5. because the dissolved salts appreciably lower the freezing point of the aqueous portion of the compositions. However. crystallization of salts as temperatures are lowered further can cause the watenbearing compositions to set up and become substantially firm and brittle at temperatures above those at which total freezing takes place. In addition to losing their desirable handling properties, solidified or frozen water-bearing compositions gcnerally become less sensitive to initiation by otherwise adequate priming agents.

This invention provides water-bearing explosive compositions having markedly improved low temperature properties. More particularly, the compositions of this invention are Water-bearing explosive compositions fluid at temperatures of lower than about 10 F. comprising a stable blend of (a) at least one water-soluble inorganic oxidizing salt, (b) at least one fuel, (c) at least 5% of water based on the total weight of composition, and (d) about from 0.25 to 10%, and preferably about 1 to 5% by weight, based on the total composition, of fluidizing I agent selected from at least one of the group consisting of compounds of the formula wherein x and y are about 2 and R is oleyl; caprylamine; sodium alkyl aryl polyether alcohol sulfonates such as the compound in which x has an average value of about 20; stearyl dimethyl benzyl ammonium chloride; polyoxyethylated fatty alcohols; compounds of the formula orn wherein R and R are selected from the group consisting of 12 to 18 carbon atom alkyl radicals; dimethyl formamide; glycerol monooleate; l-hydroxy-2-rnethoxy-4-allyl benzene; calcium cyanamid; formamide; dimethyl sulfoxide; ethylene carbonate; glycerol; acetonitrile; acetic acid; glycolic acid; methyl Cellosolve {i.c., ethylene glycol monomethyl ether); methanol; ethanol; furfuryl alcohol; diethylene glycol; sodium acetate; hexamethylene tetramine; acrylonitrilc; acetamide; glycine; tetraethylsilicate, ammonium formate; acrylamide; N,N-dimethylacetamide, and dioxane. The term fluid as used herein refers to compositions capable of being deformed continuously and permanently in any direction without rupture. As described more fully hereinafter, the compositions of this invention can vary from pourable and pumpable solutions, dispersions or slurries to moldable, tough, plastic masses.

In its broad aspects the improvement of this invention can be applied to any of the known general types of waterbearing explosives fiuid at room temperature having a continuous phase comprising water. The compositions of this invention usually contain at least about 20% by weight of inorganic oxidizing salt. Such salts include ammonium, alkali metal and alkaline earth metal nitrates and perchlorates as well as mixtures of two or more such salts. Examples of such salts are ammonium nitrate, ammonium perchlorate, sodium nitrate, sodium perchlorate, potassium nitrate, potassium perchlorate, magnesium nitrate, magnesium perchlorate and calcium nitrate. Preferably, the inorganic oxidizing salt component contains at least 45% of at least one salt which is highly soluble in water at room temperature, that is, at least as soluble as ammonium nitrate, and preferably, the aqueous phase in the compositions contains a substantial portion of oxidizing salt, for example, 40 to 70% by weight thereof. Inorganic oxidizing salt mixtures containing at least about 50% by weight of ammonium nitrate and at least about by weight of sodium nitrate are particularly preferred.

The fuels employed in the compositions of this invention can be, for example, self-explosive fuels, non-explosive carbonaceous and metallic fuels, or mixtures of the aforementioned types of fuels. The fuel or fuels used in the compositions of this invention can be varied widely, provided that in the composition in which any particular fuel is used, the fuel is stable, that is, prior to detonation, during preparation and storage, the fuel is chemically inert with the system. Self-explosive" fuel as used herein refers to a substance which by itself is generally recognized in the art as an explosive and which has a negative oxygen balance with respect to conversion to carbon dioxide, water and nitrogen. Examples of selfexplosive fuels include organic nitrates, nitro compounds, and nitramines such as TNT, pentaerythritol tetranitrate (PETN), cyclotrimethylenetrinitramine (RDX), cyclotetramethylenetetranitramine (HMX), tetryl, nitrostarch and explosive-grade nitrocellulose, as well as mixtures of the aforementioned self-explosive fuels such as, for example, pentrolite (PETN/TNT), Composition B (RDX/ TNT) and tetratol (tetryl/TNT). The self-explosive fuel can be, for example, in any of the conventional flake, pelleted or crystalline forms. The amount of fuel varies with the particular fuel employed. In general, up to 35 and, preferably, to 30% by weight based on the weight of composition of self-explosive fuel is used.

Examples of carbonaceous non-explosive fuels include finely-divided coal and other forms of finelydivided carbon; solid carbonaceous vegetable product such as cornstarch, woodpulp, sugar, ivory nut meal and bagasse; organic liquids such as hydrocarbon oils, fatty oils and vegetable oils; urea; and mixtures of two or more of the aforementioned carbonaceous non-explosive fuels. In general, up to about 25 and, preferably, 2 to by weight of such carbonaceous fuels are employed.

Metallic fuels include, for example, aluminum and iron, and alloys of such metals such as aluminum-magnesium alloys, ferrosilicon, ferrophosphorous, as well as mixtures of the forementioned metals and alloys. Although, as disclosed in U.S. Patent No. 2,836,484, up to about 50% by weight of metallic fuel can be employed in water-bearing compositions, usually on the order of 1 to 20, and preferably 1 to 8% by weight of metals such as aluminum, and on the order of about 10 to 30% by weight of heavier metallic fuels such as ferro-phosphorous and ferrosilicon are employed.

Preferably, the total amount of fuel is adjusted so that the total composition has an oxygen balance of about from to- +10% and, excepting for those compositions containing the aforementioned heavier metallic fuels such as ferrophosphorous and ferrosilicon, preferably the oxygen balance is between about 10 to +10%.

As previously indicated, the compositions of this invention contain at least about 5% by weight of water. The water-bearing compositions to which this invention is directed generally contain less than about 45% by Weight of water and, preferably, on the order of about 10 to by weight of water based on the total composition.

As previously indicated, the compositions of this invention can vary from pourable solutions, slurries and dispersions to moldable, tough, plastic masses. Thickened and particularly gelled plastic explosives are preferred. Examples of thickening and gelling agents include tree exudates such as gum arabic, ghatti, karaya and tragacanth', seaweed colloids such as agar, Irish moss, carrageenin, and the alginates; seed extracts such as locust bean, locust kernel, guar, and quince seed gums; starches and modified starches such as dextrins, hydroxyethyl starch and British gums; water dispersible derivatives of cellulose such as methyl cellulose, carboxymethylcellulose, sodium cellulose sulfate, methyl hydroxyethyl cellulose and sodium sulfoethyl cellulose; gelatin; casein; polyvinyl alcohol; polyacrylamides of high molecular weight and modified polyacrylamides containing up to 5 mole percent carboxylic acid salt groups; high molecular weight polyethylene oxides (Carbowaxes); exocellular heteropolysaccharides such as B1459 made by fermenting starch-derived sugars; as well as mixtures of the aforementioned thickening and gelling agents. Of course, such agents should be selected so that they are compatible with the explosive system employed. Of these, galactomannans and particularly guar gums are preferred because of their ready availability, their stability and general compatability with aqueous solutions of inorganic oxidizing agents. Generally, about from 0.1 to and preferably 0.5 to 5%, of such thickening and gelling agents based on the total weight of compositions are employed depending upon the particular agent selected and the consistency of explosive desired. Preferred compositions contain additionally small portions, for example, on the order of 0.001 to 1% based on the total composition, of cross-linking agents such as borax or potassium dichromate.

As previously indicated, compositions of this invention contain on the order of 0.25 to 10, and preferably 1 to 5% by weight of certain unique fluidizing agents. Within the aforementioned ranges the amounts of fiuidizing agents used vary somewhat with the particular agent selected and the temperatures at which the compositions are used. In general, larger amounts are used With the less potent agents and where lower use-temperatures are to be encountered. As indicated in the examples, certain of these fiuidizing agents yield compositions having particularly unique low temperature properties. These are methanol, formamide, climethyl sulfoxide and methyl Ccllosolve. Mixtures of the aforementioned additives also can be employed. One such mixture which is particularly unique is a substantially equiweight mixture of formamide and methanol. The aforementioned iluidizing agents also can be used in admixture with other auxiliary additives such as urea and ethylene glycol.

The compositions of this inventon can be prepared by merely mixing the various ingredients thereof to form a homogeneous mixture. Preferably, however, the Water is first used to form a concentrated, preferably saturated, solution of inorganic oxidizing salt, and to this solution are added the other ingredients including additional oxidizing salts, fuels, fluidizing agents and, optionally, gelling agents and erosslinking agents. In the case of ammonium nitrate, such aqueous solutions are commercially available in concentrations of 40 to 70% by weight under the designation of neutral liquor."

Examples of different types of compositions of this invention are those containing, based on the total composition, about from 0.25 to 10% by weight of the aforementioned fiuidizing agents and the following:

(a) 5 to 85% ammonium, alkali metal, or alkaline earth metal nitrate, or a mixture of such nitrates; 10 to 90% of TNT or mixtures thereof with other self-explosives, e.g., pentolite; 5 to 25% of water and, optionally, l to 10% of Wheat flour or 0.1 to 5% of a gelling agent such as guar gum.

(b) to 30% of ammnnium nitrate, 10 to of sodium nitrate, 20 to of TNT, 10 to 30% of ferrophosphorus, 8 to 20% of water and, optionally, 0.5 to 5% of gelling agent (oxygen balance 25 to ii0%),

(c) at least 60% of ammonium nitrate, 5 to 20% of non-exploisve carbonaceous fuel such as fuel oil, sugar, coal, cornstarch or corn meal and 5 to 20% by weight of water (oxygen balance it0%),

(d) at least of oxygen-supplying salt, at least /3 of which is ammonium nitrate, the remainder being, for example, an ammonium, alkali metal or alkaline earth metal nitrate or perchlorate such as sodium nitrate, or calcium nitrate; 0.5 to 4% of gelling agent; 2 to 20% of non-explosive carbonaceous fuel such as coal; 1 to 8% of finely-diveded aluminum and 10 to 45% by weight of water (oxygen balance il0%),

(e) 20 to 43% of ammonium nitrate, 38 to 49% of finelydivided aluminum, water (weight ratio Al/H O =1.4 to 1.5), and 0.1 to 0.5% gelatin, or

(f) ammonium nitrate or a mixture thereof with sodium nitrate; aluminum or an alloy thereof (weight ratio nitrate to metal 9/1 to 1/1) and 6 to 14% of water.

Preferred compositions of this invention are gelled slurry explosives having an oxygen balance of about from 25 to +10% comprising 20 to 50%, based on the total weight of composition, of ammonium nitrate, at least 5 and preferably 10 to 40% of sodium nitrate, 10 to 30% of self-explosive comprising TNT, 5 to 30% of water, about 0.1 to 5% of gelling agent and about from 1 to 5% by weight of fiuidizing agent.

In the following more detailed examples which illustrate this invention, parts and percentages are by weight unless otherwise indicated.

EXAMPLE 1 In a stirred kettle, 50 parts of ammonium nitrate solution is brought to a temperature of F, and to it is added with continuous agitation 3 parts of formamide, then 25 parts by weight of crystalline sodium nitrate uniformly premixed with a mixture of 0.75 part of commercial guar gum. The contents of the kettle are stirred for three minutes, and then there is added 0.75 part of 5% potassium dichromate solution while agitation is continued, and about 15 seconds later 25 parts of commercial flaked TNT is added. Stirring is continued for about 5 minutes to obtain a substantially homogeneous mixture which then is extruded into 1 /2 diameter polyethylene bags. The bagged composition is aged for one day at ambient room temperature, and then is placed in storage at controlled low temperatures for designated periods of time after which the composition is tested for fluidity, as described below.

A control composition is prepared, packaged and aged as described above except that the three parts of formamide are omitted.

The low temperature fluidity of the composition of this invention shown above as well as that of the control and the compositions of this invention shown in the following examples is determined by storing the compositions packaged and aged as just described at a test temperature for at least 24 hours, then applying pressure to the packaged compositions by squeezing them by hand. Compositions which, under hand pressure, do not yield or yield with fracture are rated poor. Those which deform without fracture are useful over a range of temperatures down to the test temperature and are rated fair, good, or very good depending upon the extent of improvement in fluidity as compared with the control at the test temperature.

his is a test similar to that used in the field to judge the low temperature handling and shaping properties of explosive compositions during loading operations.

The composition of this invention described above containing forrnamide is tested at l0, l5 and 20 F. and is judged very good at each such test temperature. The control composition is hard and not subject to deformation without fracture under hand pressure at each of such temperatures. At room temperature, both the composition of this invention and the control composition can be deformed readily without fracture. The composition of this invention has satisfactory sensitivity and detonating properties both at room temperature and at the test temperatures.

EXAMPLES 2 TO 35 Compositions of this invention are prepared by the procedure and from the materials used to prepare the composition of this invention described in Example 1 excepting that the fluidizing agents and amounts thereof indicated in Table I are substituted for the three parts of form-amide used in that example. The low temperature Table I Fluldizing action 2 Fluidizing agent Cone.

"Arquntl" 12-50 Uimcthyl formamide.

Glycerol monooleatc.

Eugcnol Calcium cyanomidm Forinaniide.

Dimethyl sulloxir c Ethylene carbonate.

(llyeolie acid .tlethyl Crllosolve l [1 formann'deethylene glycol. Methanol Ethanol l urturyl alcohl. Diethylcnc glycol." Sodium acetate llcxam thyleue tctrmnino.

lliosuue Acrylonitrilc. A cetanrido Glycine. 'letrueth, t Ammonium iormate Arr 'lumitle N.l\climvthyl acct-nitride.

OQCCOO SOsNEL (DC llgClIzhOll \vhcrr-in x has an average value of 20.

6 paste of stearyl (lirncthyl bunny] ammonium chloride. l lolyoxyethylated fatty alcohol. Water and 50% by weight of a mixture of compounds of the formula:

R: C lls wherein R1 and R: are mixed nilryl groups averaging about 00% by weight tludceyl. 0% tctrittlocyl and 1% octatlecyl.

l-hydroxy-Z-uicthoxy-l-allyl benzene.

EXAMPLES 36 and 37 In a like manner the fiuidizing agents listed in Table I in the amounts shown therein can be incorporated in the following compositions.

EXAMPLE 36 Ingredient: Parts Ammonium nitrate 22.2 Sodium nitrate 15.0

TNT 27.0

Ferrophosphorus 20.0 Water 15.0 Guar gum 0.75

Fluidizing agent 1.5 to 5 Pa EXAMPLE 37 Ingredient: Parts Ammonium nitrate 52.0 Calcium nitrate 15.0 Finely-divided aluminum 4.0 Powdered coal 5.4

Water 22.0 Guar gum 1.6 Fluidizing agent 1.5 to 5 We claim:

1. Water-bearing explosive compositions fluid at a temperature of lower than about -10 F. comprising a stable blend of (a) at least one water-soluble inorganic oxidizing salt, (b) at least one fuel, to) at least 5% by weight of water based on the total composition, and (d) about from 0.25 to 10% by weight, based on the total composition, of [fluidizing agent selected from at least one of the group consisting of compounds of the formula R-N-(-C1l Cll O-)rH Clon o1no- ,rr wherein x plus y equals 2 and R is oleyl; caprylaminc; sodium alkyl aryl polyether alcohol sulfonates; stearyl dimethyl benzyl ammonium chloride; polyoxyethylated fatty alcohols; compounds of the formula R1 Gin N C1- m (11 wherein R; and R are selected from the group consisting of 12 to 18 carbon atom alkyl radicals; dimethyl formamidc; glycerol monooleate; l-hydroxy-2-methoxy-4-allyl benzene; calcium cyanamide; formamide; dimethyl sulfoxide; ethylene carbonate; glycerol; acetonitrile; acetic acid; giycolic acid; methyl Ccllosolve; methanol; ethanol; furfuryl alcohol; diethylene glycol; sodium acetate; hexamethylene tetramine; acrylonitrile; acetamide; glycine; tctraethylsilicatc; ammonium formate; acrylamide; N,N- dimethylacetamide; and dioxane.

2. A composition of claim 1 wherein said fluidizing agent comprises formamide.

3. A composition of claim 1 wherein said fiuidizing agent comprises methyl Cellosolve.

4. A composition of claim 1 wherein said fluidizing agent comprises dimethyl sulfoxide.

5. A composition of claim 1 wherein said fiuidizing agent comprise-s methanol.

6. A composition of claim 1 wherein said fluidizing agent comprises a mixture of methanol and f-ormamide.

7. A gelled slurry explosive composition fluid at a temperature of lower than about -10 F. and having an oxygen balance of about from -25 to +10% comprising a stable blend of, based on the total composition, about from 20 to 50% by weight of ammonium nitrate, about from 10 to 40% by weight of sodium nitrate, about from 10 to 30% by weight of self-explosive comprising TNT, about from S to 30% by Weight of water, about from 0.1 to 5% of gelling agent and about from 0.25 to 10% by weight of fluidiz'ing agent selected from at least one of the gr up consisting of compounds of the formula wherein at plus y equals 2 and R is oleyl; caprylamine; sodium alkyl aryl polyether alcohol sulfonates; stearyl dimcthyl benzyl ammonium chloride; polyoxyethylated fatty alcohols; compounds of the formula R on;

N C1 It on wherein R and R are selected from the group consisting of 12 to 18 carbon atom alkyl radicals; dimethyl formamide; glycerol monooleate; 1-hydroxy-2-rnethoxy-4-allyl benzene; calcium cyanamide; formamide; dimethyl sulfoxide; ethylene carbonate; glycerol; acetonitrile; acetic acid; glycolic acid; methyl cellosolve; methanol; ethanol; furfuryl alcohol; diethylene glycol; sodium acetate; hexamethylene tetramine; acrylonitrile; acctamicle; glycine; tetracthylsilicate; ammonium formate; acrylamide; N,N- dimethylacetamide; and dioxane,

8. A composition of claim 6 wherein said fiuidizing agent comprises about from 1 to 5%, based on the total weight of composition, of formamide.

9. A composition of claim 6 wherein said fiuidizing agent comprises about from 1 to 9%, based on the total weight of composition, of dimethyl sulfoxide.

10. A composition of claim 6 wherein said fiuidizing agent comprises about from 1 to 5%, based on the total weight of composition, of methyl Cellosolve.

11. A composition of claim 6 wherein said fluidizing agent comprises about from 1 to 5%, based on the total weight of composition, of methanol.

References Cited by the Examiner UNITED STATES PATENTS 2,930,685 3/60 Cook et a] 1492 X 2,976,137 3/61 Stengel 1495l X 3,031,289 4/62 Philipson 14976 X 3,039,903 6/62 Enokoson l4949 X CARL D. QUARFORTH, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 190, 777 June 22 1965 Cyril J. Breza et al.

It is hereby certified that error ent requiring correction and that the corrected below.

appears in the above numbered patsaid Letters Patent should read as 0 In the grant, lines 2 and 3, and in the heading to the printed specification, line 5, for "Hartwell H. Eassnacht",

each occurrence, read Hartwell H. Fassnacht column 8,

lines 72 to 75, the formula should appear as shown below instead of as in the patent:

R CH3 \N/ (:1- R2/ cn column 9, lines 11 and 14 and column 10 lines 1 and 4 for the claim reference numeral "6", each occurrence, read 7 column 9, line 15, for "9%" read 5% Signed and sealed this 29th day of March 1966.

SEAL) 121265112 RNEST W. SWIDER EDWARD J. BRENNER ttesting Officer Commissioner of Patents

Claims (1)

1. WATER-BEARING EXPLOSIVE COMPOSITIONS FLUID AT A TEMPERATURE OF LOWER THAN ABOUT -10*F. COMPRISING A STABLE BLEND OF (A) AT LEAST ONE WATER SOLUBLE INORGANIC OXIDIZING SALT, (B) AT LEAST ONE FUEL, (C) AT LEAST 5% BY WEIGHT OF WATER BASED ON THE TOTAL COMPOSITION, AND (D) ABOUT FROM 0.25 TO 10% BY WEIGHT, BASED ON THE TOTAL COMPOSITION, OF FLUIDIZING AGENT SELECTED FROM AT LEAST ONE OF THE GROUP CONSISTING OF COMPOUNDS OF THE FORMULA