CA1096174A

CA1096174A - Explosive composition and process for its manufacture

Info

Publication number: CA1096174A
Application number: CA289,477A
Authority: CA
Inventors: George H. Barnett; Frederick Bolza
Original assignee: ICI Australia Ltd
Current assignee: Orica Ltd
Priority date: 1976-10-25
Filing date: 1977-10-25
Publication date: 1981-02-24
Also published as: NZ185330A; ZA776302B; BR7707063A

Abstract

ABSTRACT OF THE DISCLOSURE
An explosive composition of matter of the so called dry mix type comprising a mixture of water insoluble carbonaceous fuel material and a reaction product having an oxygen balance in the range from +20 to +35% and derived from the reaction of an organic fuel material with a calcium salt.

Description

- 2 -This invention relates to inorganic salt based explosive compositions. More particularly the invention relates to explosive compositions of the so-called dry mix type and which comprise a reaction product of a calcium salt and organic fuel material.
Explosive compositions of the dry mix type are known and a typical example of such a composition is a physical mixture of ammonium nitrate and fuel oil which is commonly referred to as ANF0 and which has been used extensively in mining operations.
Such compositions have been modified as for instance as described in USA Patent Specification 3,061,488 wherein sodium nitrate is admixed with ammonium nitrate as an oxygen releasing salt com-~- ponent; or as in USA Patent Specification 3,178,325 wherein the oxidizing salt is selected from a range of nitrates and the fuel component comprises a highly toxic mononitroaromatic com-. pound. There has also been proposed in Canadian Patent Specifi-cation 885924 a blasting agent of the dry mix type comprising a physical mixture of diesel fuel oil, coated ammonium nitrate and a metal nitrate such as an alkaline earth nitrate, lithium nitrate, potassium nitrate or lead nitrate. It was taught in such specifications that it was highly desirable, and sometimes essential, that the oxygen balance of the compositions should be maintained in a narrow range which included an oxygen balance value of zero, and which was usually within the range from +1 to -1% and rarely beyond the range from +7 to -7%.

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With the passage of time other so-called dry mix explosive compositions have been proposed such as in United States Patent Specification 3,839,107 wherein there is described an explosive composition containing a mixture of calcium nitrate, a water miscible organic fuel and water, or in United States Patent Specification 3,816,191 wherein there is described a method for making such a composition by mixing ammonium nitrate and a liquid water miscible organic fuel and then reacting the mixture with lime, or in United States Patent Specification 3,899,374 which describes an explosive composition containing a mixture of calcium nitrate as the predominate inorganic oxidizing com-ponent, a water-miscible organic fuel and water and having an oxygen balance ranging from ~20 to -8%.
We have now discovered a new explosive composition of matter of a dry mix type which differs essentially from the explosive compositions referred to above in that it comprises an organo-calcium component which has a positive oxygen balance. In general terms our discovery relates to explosive compositions of the dry mix type which comprise an organo-:, . .
caloium compound in admixture with an amount of water-insoluble fuel material. The organo-calcium compound may be deri~ed from a calcium salt which is capable of reacting with an organic fuel material as hereinafter described. Very suitably the calcium salt is of the oxygen-releasing type such as a nitrate or a perchlorate. Preferably the organo-calcium compound is : .. :
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derived from calcium nitrate. Any grade of a suitable calcium salt may be used to form the organo-calcium component of the compositions of the invention. Thus for example anhydrous grades ie those which are substantially free from water of hydration or absorbed water, or mono- or tetra-hydrated forms, as well as water or organic liquid solutions of the hydrated salt are useful. A particularly useful salt is an impure calcium nitrate available commercially in the form of prills or flakes and used as a fertiIizer. Such salt contains a small amount of ammonium nitrate and a typical analysis thereof is approximately 4.5% w/w ammonium nitrate, 80.5% w/w calcium nitrate, 14.4% wjw water with the remainder being inert material.
When desired such prills can be converted to a powdered form prior to reacting them with the organic fuel material.
During the course of our experimentation it has been found that very useful explosive compositions are those where-in the oxygen balance of the organo-calcium component is at ; least +20% and preferably lîes in a range from +20 to + 35%.
By the term "oxygen balance" is meant the amount of excess or paucity of oxygen expressed as the percentage of +grams or -grams of oxygen per 100 grams of total product when combusted.
Accordingly in an embodiment of our invention there is provided an explosive composition of matter comprising a mixture of water-insoluble carbonaceous fuel material and an organo-calcium material having an oxygen balance in the range from +20 .

to +3~ and derived from the reaction o~ an organic lucl material with a calcium salt.
Suitably the water insoluble carbonaceous fuel material may be hydrocarbon oils, fuel oils such as diesel fuel oil, fatty oils or vegetable oils or a hard hydrocarbon such as comminuted coke or charcoal, or carbon black or vegetable products such as starch~ nut meal or wood pulp, or mixtures of two or more of these fuels. Diesel fuel oil is a preferred such material.
Suitable organic fuel materials used in the preparation ~` of the organo-calcium reaction product include organic compounds and mixtures thereof which contain one functional group selected from the group consisting of =0~ -OH, =NH~ -NH2, =S and -SH
and which when mixed and reacted with a calcium saltl~such as calcium nitrate~on a molecular scale form a chemical complex or adduot therewith. Examples of such fuel materials include certain amines~ including primary and secondary types; amides;
alcohols including both mono- and polyhydric alcohols; alcohol ethers; amino acids, aldehydes and derivatives thereof. Specific compounds include, for example~ ethylenediamine, thiourea, formamide~ acetamide, urea, glycerol, ethylene glycol, ethylene glycol mononitrate, methylamine, ethylamine, hexamine, methanol, isopropanol, amyl alcohol, decyl alcohol, glycine, and formaldeh~de. The fuel materials may be solids at room tempera-ture, but so as to facilitate their manufacture it is preferred . . ~ . : .

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-- 6 -- .-that the compositions be made from materials which are in the form of a liquid. Particularly suitable fuels include liquid fuels, especially such fuels containing one or more hydroxy groups. Other organic fuels which are useful include vegetable oils and derivatives thereof such as ricinoleic acid, ricinoleyl alcohol or safflower oil.
The compositions of the invention may be prepared using processes and apparatus used conventionally for the mixing of materials. Thus for example in the instance where the organic fuel component is liquid a composition may be prepared by placing a calcium salt in the form of a powder or prills in a reaction vessel fitted with mixing and cooling means and adding to the agitated salt a desired amount of organic fuel. The orga ^ fuel may be added in aliquots or as an intermittent or continuous stream of liquid or vaporized fuel and a preferred method of adding the organic fuel component is in the form of a spray.
The heat of reaction created in the process may be dissipated by application of the cooling means if desired, but such heat is a convenient source of energy to convert the reaction product to a dry, comminutable form which is then added to and mixed with the water-soluble carbonaceous fuel component to provide an explosive composition of the invention. In the instance where the organic fuel is solid at ambient temperatures it is convenient that both the calcium salt and the organic fuel be in a finely divided form so as to facilitate reaction between the .;
' components and it is often convenient that the reaction be performed at a temperature above ambient temperature, say in a range from about 30 to 100C. In these instances the reaction product is usually formed at a slower rate than in instances where the organic fuel component is liquid. A
convenient means for monitoring the progress of the reaction between the components is by examination of content of the reaction vessel using X-ray diffraction powder pattern photography. The adduct resulting from the reaction between the components is then addea to and mixed with the water-insoluble carbonaceous fuel component to form a composition according to the invention. The compositions of the invention may if desired be modified by subjecting them to a heat treatment. For example if such compositions are heated at moderately elevated temperatures, say in a range from 60 to 90C, it has been found that the compositions become more dense, thus allowing a greater weight to be located in a unit of volume of a borehole, and, furthermore, the velocity of detonation is usually increased in comparison with the unmodified compositions.
The proportions of the components of the compositions of the invention may be varied over a wide range dependent to some extent of the type and nature of the materials used to form the composition and the energy characteristics required from the composition. The proportions of the components are also limited by the characterizing values of the oxygen balance of the composition as hereinbefore aescribed.
Still further the - " -proportion~ all( limitcd by th~ ~e~ir;lbility tllat th( (~om-positions should bc substantially dry and thus car~ has to bc exercised in the choice of the amount of water insoluble carbonaceous fuel material or the organic fuel material when 5 one or either of these types of material is a liquid. So as to provide an illustration of a range of compounds reference is made to compositions wherein the organo-calcium component is derived from ethylene glycol and calcium nitrate, the water insoluble carbonaceous fuel material is diesel fuel oil, and optionally the compositions may contain additionally an amount of an inorganic oxygen-releasing salt such as ammonium nitrate.
Even when the amount of diesel fuel oil constitutes as little as 3% w/w of the composition, satisfactory detonation of the compositions is possible. It has been demonstrated that satis-factory compositions can contain up to about 9% w/w of fuel oil and it is envisaged that the amount of water-insoluble carbon-aceous fuel material could be increased to a somewhat higher proportion of the compositions, say up to about 12% w/w, with-out detriment to the physical or explosive properties of the compositions. It has also been demonstrated that satisfactory explosive compositions ma~ be prepared from the above materials if the organo-calcium reaction product is derived from calcium nitrate and ethylene glycol in a molar ratio which is in a range from about 2:1 to about 7:1.
The organo-calcium component of the compositions of the '~ . .

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invention has an oxygen balance which is similar to that of ammonium nitrate which is approximately +20%, and accordingly -1 the compositions of the invention may be used for purposes for which ANF0 compositions have been used previously. The com-S positions of the invention are advantageous over conventional ANF0 compositions in that the density of the new compositions may be adjusted if desired by suitable choice of the type and proportions of the components, to values which are greater than is obtainable with conventional ANF0 explosives. This capability of providing greater density values has the attendant advantage that a greater weight of the new compositions can be located in a unit volume of a borehole and thus in many instances an increase of available energy per unit volume of borehole can be obtained during blasting operations. This provision of greater energy is of commercial significance in blasting and mining operations especially when such operations involve the drilling of boreholes in very hard ground such as is found in deposits of iron ~re.
The compositions of the invention or precursors thereof may be used to replace a part of conventional dry-mix type of explosive compositions. For example they may be used to re-place oxygen releasing inorganic salts used conventionally in such compositions. Typically the organo-calcium component of the compositions of the invention may be used to replace part of the ammonium nitrate in a conventional ANF0 composition.

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- ~g6~4 Typical organo-calcium compounds suit.lblc ~or usc as r~pl.lce-ments for components of conventional .~NF0 compositions include those where such compounds have been derived from the reaction of a calcium salt, such as calcium nitrate, and a suitable organic fuel material in a molar ratio in a range from about 1:1 to about 10:1. Whilst such organo-calcium compounds may replace all the ammonium nitrate component of a conventional ANF0 composition without detriment to the blasting capability of the composition, it is more usual to replace only a part of the ammonium nitrate component and typically the degree of replacement is such that the ratio of moles of ammonium nitrate in the composition to the moles of calcium salt used to form the organo-calcium compound is in a range from about 0.2:1 to about 11:1. When such a replacement is effected the ratio of the weight of the calcium salt used to form the organo-calcium material to the weight of water insoluble carbonaceous fuel material, typically vegetable oil or diesel fuel oil, in the composition is conveniently in a range from about 2:1 to about 15:1.
Accordingly in a further embodiment of the invention there is provided an explosive composition of the dry mix type which comprises as a first component a mixture of water-insoluble carbonaceous fuel material, preferably fuel oi~ and ammonium nitrate and as a second component an organo-calcium material as hereinbefore described .
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provide an cxplosive composition of thc dry mix type which comprises as a first component a mixture of ammonium nitrate and fuel oil and as a second component an explosive com-S position according to the invention.
It will be understood that in the compositions of the invention and embodiments thereof as set out above there may be present additional components which may be present con-ventionally in ANFO compositions such as other oxygen releasing salts for instance sodium nitrate; fuel gelling agents such as aluminium stearate; metallic fuels for instance aluminium powder; void producing matter such as glass microballoons or retiporous or vesiculated polymeric particles, which may ~
used to modify the compositions of theinvention by minor changes.
The compositions of the invention have an added advantage over the ammonium nitrate based dry mix explosives of the prior art in that calcium salts, such as calcium nitrate, are less hazardous to transport and use than is ammonium nitrate.
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Our invention is now illustrated by, but is not limited to, the following examples wherein all parts and percentages are expressed on a weight basis unless otherwise specified.
S Example 1 Into a reaction vessel fitted with mixing means there was placed 86 parts of crushed prills of fertilizer grade calcium nitrate and whilst the calcium nitrate was agitated by the mixing means there was added to the reaction vessel 5 parts of ethylene glycol in the form of a spray.
As the components reacted heat was evolved and the content of the vessel changed from a moist mixture to a uniform powder which to the eye and feel of an observer was in a dry form. The reaction product so obtained was cooled and was then mixed with 9 parts of diesel fuel oil to provide an explosive composition according to the invention. The ex-plosive so obtained had a density of 1.30 grams per cubic centimetre and when placed in a cylindrical steel pipe having a diameter of 5 centimetres it was detonated at a temperature of 18C by means of a 100 gram pentolite booster.
The velocity of detonation was 2.3 kilometres per second.
Examples 2 to_4inclusive Explosive compositions according to the invention were prepared by the general procedure of Example 1 except that in these examples the amounts of calcium nitrate and ethylene organo-calcium glycol were varied to provide a range of/reaction products . . .

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and tllc .lmount o~ dicscl ~ucl oil whicll wa.~ admixed wi.tll the reaction products was varied also to provide a rangc of explosive compositions. The amounts of raw materials used I are set out in Table 1.

! TABLE 1 ~ Calcium Ethylene Diesel fuel Example nitrate glycol oil No (parts) (parts) (parts)

3 873 51 76 1 4 875 _ 5 74 Examples 5 to 10 inclusive To each of the explosive compositions prepared as described in Examples 2 to 4 inclusive there was added and . mixed an amount of a mixture of ammonium nitrate of the type shown in Table 2 and fuel oil in a weight ratio of 94:6. The dry mix explosive so obtained was placed in a cylindrical steel pipe of 5 centimetres diameter and detonated using a pentolite booster. The denslty of the dry mix explosive, the amount of booster used to detonate it and the velocity of detonation (VOD) are shown in Table 2.

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Example 11 55 parts of ethylene glycol were placed in a reaction vessel provided with stirring means and cooling means. To the stirred ethylene glycol there was added slowly 345 parts of powdered anhydrous calcium nitrate so as to form a slurry. The slurry so formed was stirred and the temperature of the content of the reaction vessel was observed to increase. Stirring was continued until the content of the reaction vessel became dry and solid whereupon the content of the vessel was cooled to room temperature, removed from the vessel and comminuted. To ! 10 the comminuted composition there was then added 30 parts of fuel oil and the mixture so obtained was added to and mixed with 470 parts of a conventionally prepared explosive of the ANFO type wherein the weight proportion of the ammonium nitrate component to fuel oil component was in a ratio of 94:6.
The composition so obtained had a density of 0.9 gram per cubic centimetre and after being placed in a cylindrical steel tube having an internal diameter of 5 centimetres it was detonated using a booster containing 20 grams of pentolite. The velocity of detonation was 3 kilometres per second.
E~ample 12 51 parts of ethylene glycol and 74 parts of vegetable ; oil were placed in a reaction vessel provided with stirring means and cooling means. The above components were stirred and to them was added 875 parts of finely ground calcium nitrate so as to form a paste. This paste was stirred and the -`: ': : -; - - ':
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1`7 temperature of the content of the reaction vessel was observed to increase. Stirring was continued until the content of the reaction vessel became dry and solid whereupon the content of the vessel was cooled to room temperature, removed from the vessel and comminuted. To the comminuted explosive material so obtained there was then added 784 parts of a composition con-sisting of porous ammonium nitrate prills and vegetable oil in a weight ratio of 94:6 to provide another explosive com-position. This explosive composition which had a density of 0.9 gram per cubic centimetre was placed in a steel pipe having an internal diameter of 5 centimetres and was detonated using a 20 gram pentolite booster. The velocity of detonation was 2.5 kilometres per second.
ExamPle 13 An explosive composition was made by the general procedure of Example 12 except that the ethylene glycol of that example was replaced by 51 parts of amyl alcohol, and the 74 parts of vegetable oil of that example was replaced by 74 parts of fuel oil. The composition so obtained had a density of o.85 gram per cubic centimetre and after being placed in a cylindrical steel tube having an internal diameter Or 5 centimetres it was detonated using a booster containing 10 grams of pentolite.
The velocity of detonation was 3.4 kilometres per second.
Example 14 An explosive composition was made by the general procedure of Example 13 except that the amylalcohol of that example was replaced by 51 parts of triethylene glycol. The composition so obtained had a density of 0.9 gram per cubic centimetre and after being placed in a cylindrical steel tube having an internal diameter of 5 centimetres it was detonated using a booster con-taining 20 grams of pentolite. The velocity of detonation was 3.1 kilometres per second.
Example 15 In a reaction vessel fitted with mixing means a mixture of 18 parts of hexamethylenetetramine (HMT) and 182 parts of powdered fertilizer grade calcium nitrate (C~) were reacted at 20C to form a reaction product on to which 12 parts of diesel fuel oil (F0) were sprayed. The resultant first explosive composition was then added to and mixed with 888 parts of a mix-ture of crushed prilled ammonium nitrate and fuel oil (ANF0) in a weight ratio of 94:6 to form a second explosive of the dry mix type. This second explosive was placed in a cylindrical cardboard tube which had an internal diameter of 4 centimetres.
The second explosive mixture had a density of 0.9 gram per cubic centimetre and it was detonated by means of a No 8 aluminium detonator. The velocity of detonation was 3.1 kilo-metres per second.
ExamPles 16 to 18 inclusive Explosive compositions were prepared by the general procedure of Example 15 but using amounts of the components as ::

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set out in Table 3. In Table 3 there is also set out the density of the explosive, the velocity of de~onation ana the amount of pentolite in the booster which was used to initiate detonation in a cylindrical steel tube having an internal diameter of 5 centimetres.

Example HMT CN FO ANFO Density Pentolite VOD
(parts) (parts) (parts) (parts) (gm/cc) (gm) km/sec.

16 36 364 24 576 0.99 20 3.3 17 54 546 36 364 1.02 20 2.8 18 72 728 48 152 1.08 50 2.8 .
Example 19 An explosive composition was prepared by reacting 40 parts of urea and 160 parts of powdered fertilizer grade calcium nitrate at ambient temperature to form an adduct, spraying the adduct with 12 parts of diesel fuel oil and then ~ adding and mixing therewith 888 parts of ANFO prepared from i; crushed prills of a coated explosive grade ammonium nitrate and fuel oil in a ratio of 94:6. The adduct had a density of 1.0 gram per cubic centimetre and when detonated by a No 8 aluminium detonator in a cylindrical cardboard tube of internal diameter 4 centimetres it had a velocity of detonation of 2.8 kilometres per second.

Exam les 20 to 22 inclusive p 2~ Explosive composition were prepared by the general ~ `

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procedure of Example 19 but using amounts of the components as set out in Table 4. In Table 4 there is also set out the density of the explosive, the velocity of detonation and the amount of pentolite in the booster which was used to initiate detonation in a cylindrical steel tube.

Example Urea CN I F0 (parts) Density Pento- seo Tube _ 3~ 24 576 o.97 5 3.2 3.7 21 120 480 36 364 o.98 50 3.1 3.7 22 160 640 48 152 1.02 loO 2.7 5.0 Example 23 An explosive composition obtained by the procedure of Example 19 was heated with agitation for two hours at a temperature of 80C and then cooled to room temperature. The product so obtained had a density of 1. 23 grams per cubic centimetre and when detonated in a cylindrical steel pipe having an internal diameter of 5 centimetres by means of 100 grams of pentolite it had a velocity of detonation of 3.2 kilometres per second.

ExamPle 24 An explosive composition obtained by the procedure of Example 20 was heated with agitation for three hours at a temperature in a range from 75 to 80C and then cooled to ::

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room temperature. The product so obtained had a density of 1.32 grams per cubic centimetre and when detonated in a cylindrical steel pipe having aninternal diameter of 5 centi-metres by means of 100 grams of pentolite it had a velocity of detonation of 4 kilometres per second.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An explosive composition of matter comprising a mixture of water-insoluble carbonaceous fuel material and an organo-calcium material having an oxygen balance in the range from 20 to 35% and derived from the reaction of organic fuel material with a calcium salt.

2. A composition according to Claim 1 wherein the said water-insoluble carbonaceous fuel material is selected from the group consisting of fuel oils and vegetable oils.

3. A composition according to Claim 2 wherein the said fuel oil is diesel fuel oil.

4. A composition according to any one of Claims 1, 2 or 3 wherein the said organic fuel material is selected from the group consisting of organic compounds which contain a functional group selected from the group consisting of =O, -OH, =NH, -NH2, =S and -SH and which are reactable with a calcium salt so as to form a chemical complex or adduct therewith.

5. A composition according to Claim 1 wherein the said organic fuel material is selected from the group consisting of amines, monohydric alcohols, polyhydric alcohols, alcohol ethers, amides, amino acids and aldehydes.

6. A composition according to Claim 1 wherein the said organic fuel material is a vegetable oil.

7. A composition according to Claim 5 wherein the said polyhydric alcohol is a glycol.

8. A composition according to Claim 7 wherein the said glycol is selected from the group consisting of ethylene glycol and triethylene glycol.

9. A composition according to Claim 5 wherein the said organic fuel material is selected from the group consisting of amyl alcohol, hexamethylenetetramine and urea.

10. A composition according to any one of Claims 1, 2 or 3 wherein the said water-insoluble carbonaceous fuel material constitutes at least 3% w/w of the composition.

11. A composition according to Claim 1 wherein there is present an amount of a further inorganic oxygen-releasing salt.

12. A composition according to Claim 11 wherein the said further inorganic oxygen-releasing salt is ammonium nitrate.

13. A composition according to Claim 11 wherein the ratio of moles of said further inorganic oxygen-releasing salt component to moles of calcium salt used to form said organo-calcium component is in a range from 0.2:1 to 11:1.

14. A composition according to any one of Claims 11, 12 or 13 wherein the ratio of the weight of the calcium salt used to form the said organo-calcium component to the weight of the said water-insoluble carbonaceous fuel component is in a range from 2:1 to 15:1.

15. A composition according to Claim 1 wherein the said organo-calcium material is derived from a calcium salt and organic fuel material in a molar ratio in a range from 1:1 to 10:1.

16. A composition according to Claim 15 wherein the said calcium salt is calcium nitrate.

17. A composition according to Claim 16 wherein the said calcium salt is calcium nitrate, the said organic fuel material is ethylene glycol and the said ratio is in a range from 2:1 to 7:1.

18. An explosive composition of matter comprising as a first component a mixture of ammonium nitrate and fuel oil and as a second component a composition according to any one of Claims 1, 2 or 3.

19. An explosive composition of matter comprising as a first component a mixture of ammonium nitrate and fuel oil and as a second component an organo-calcium material derived from the reaction of organic fuel material with a calcium salt.

20. A process for the manufacture of an explosive composition of matter which process comprises first reacting a calcium salt with an organic fuel material selected from the group consisting of organic compounds which contain a functional group selected from the group consisting of =O, -OH, =NH, -NH2, =S and -SH so as to form an organo-calcium material having an oxygen balance in the range from +20 to + 35%, and secondly adding to and mixing with said organo-calcium material an amount of water-insoluble carbonaceous fuel material such that the said carbonaceous fuel material constitutes at least 3% w/w of the composition.