Explosive and thermic compositions or charges – Structure or arrangement of component or product
Reexamination Certificate
1999-08-20
2002-07-30
Carone, Michael J. (Department: 3641)
Explosive and thermic compositions or charges
Structure or arrangement of component or product
C149S019400, C149S109600
Reexamination Certificate
active
06425965
ABSTRACT:
FIELD OF INVENTION
The present invention relates to an ultra low density particulate composition, particularly one which can be used alone, or mixed with other explosive compositions to modify their properties.
BACKGROUND TO THE INVENTION
Ammonium nitrate and fuel oil explosive compositions (ANFO) have been used extensively for commercial blasting since the 1950's. In addition to being used alone, ANFO has also been incorporated into slurry and emulsion explosives as means of modifying the performance and/or the density of such explosives.
Explosives are usually purchased on a weight basis and therefore the density of the explosive compositions is sometimes a factor in determining the selection of an explosive for a particular job. Common low density inert agents are expanded perlite and glass bubbles. Other ingredients have also been used. Gotz et al. in E. German patent 246 457 which was published Jun. 10, 1987 discloses an explosive with 10-80 vol. % ammonium nitrate treated with 0-1 vol. % diesel fuel and 90-20 vol. % foamed polystyrene. U.S. Pat. No. 5,505,800 to Gribble et al. which issued Apr. 9, 1996 discloses an ANFO explosive with some or all of the fuel oil replaced with a solid fuel, e.g. gilsonite, coal, rubber, polystyrene. U.S. Pat. No. 4,957,569 to Waldock et al., which issued Sep. 18, 1990 discloses an emulsion explosive with oxidizer salts held in a disperse phase in oil, to which bulking agents such as sawdust, foamed polystyrene beads, perlite or vermiculite have been added. Russian patent 1601972 published Jul. 9, 1995 discloses explosive compositions containing granular ammonium nitrate and polystyrene, with the latter being expanded in a hot aqueous solution of ethylene glycol as an inherent stage of the composition's manufacturing process.
The present invention is directed to other means for lowering the density of particulate explosives.
The terms “comprising” and “comprises” when used in this specification are taken to specify the presence of the stated features, integers, steps or components but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.
SUMMARY OF INVENTION
Accordingly, the present invention provides an explosive composition comprising a mixture of:
a) a particulate synthetic polymeric low density agent coated with from 5 to 30 wt. %, based on the low density agent weight, of a first wetting agent which comprises a first flowable carbonaceous fuel and a first tackifying agent for said first flowable carbonaceous fuel; and
b) a particulate oxidizing agent, coated with a second wetting agent which comprises a second flowable carbonaceous fuel and a second tackifying agent for said second flowable carbonaceous fuel.
The term “flowable carbonaceous fuel”, in the present context, refers to carbonaceous fuels which can flow under gravity without excessive heating, e.g. flows at temperatures less than about 110° C. The term encompasses those fuels which flow at room temperature or below, e.g. mineral oil, lubricants, as well as those, e.g. molasses, greases, light waxes and sugars which require moderate heating.
The terms “tackifying agent” and “tackifier” as used herein are synonymous and refer to agents for tackifying oils. Such terms are understood in the petroleum and synthetic lubricant arts. Tackifiers may be used, for example, in motor oil, mineral oil and the like.
In one embodiment, the second wetting agent is the same as the first wetting agent.
In one embodiment, the particulate low density agent is selected from the group consisting of synthetic thermoplastic polymer bubbles and expanded synthetic carbonaceous polymers.
In a further embodiment, the expanded synthetic carbonaceous polymer is selected from the group consisting of a foamed polystyrene, a foamed polyurethane, a foamed polyolefin and mixtures thereof.
In another embodiment, the expanded synthetic carbonaceous polymer has a density of less than about 0.1 g/cm
3
.
In one embodiment, the polyolefin is polyethylene.
In yet another embodiment, the preferred particulate low density agent is a foamed polystyrene having a density of less than about 0.05 g/cm
3
.
In another embodiment, the flowable carbonaceous fuel is selected from paraffinic oils, vegetable oils, greases, light waxes, saccharose, glucose, fructose, maltose, molasses and mixtures thereof. Preferred flowable carbonaceous fuels are paraffinic oils, vegetable oils, sugar based fuels and light waxes. Examples of paraffinic oils include mineral oils, lubricating oils, fuel oils and diesel oils. Preferred paraffinic oils are mineral oils and lubricating oils. Most preferred is mineral oil.
In a further embodiment, the first and second tackifying agents are high molecular weight hydrocarbons
In yet another embodiment, the first and second tackifying agents are ethylene-propylene copolymers.
In another embodiment, the particulate oxidizing agent is selected from alkali metal nitrates, alkaline earth metal nitrates, alkali metal chlorates, alkaline earth metal chlorates, alkali metal perchlorates, alkaline earth metal perchlorates, urea nitrates, guanidine nitrates and mixtures thereof. Preferred oxidizing agents are ammonium nitrate, calcium nitrate and sodium nitrate.
In a further embodiment, the particulate oxidizing agent passes through a 14 U.S. Standard mesh.
In yet another embodiment, the explosive composition also contains a particulate explosive compound selected from aromatic organic explosives, aliphatic organic explosives and mixtures thereof.
In yet another embodiment, the particulate explosive compound is selected from pentaerithrytol tetranitrate (PETN), cyclotrimethylenetrinitramine (RDX) and trinitrotoluene (TNT), tetramethylenetetranitramine (HMX), nitroguanidine and mixtures thereof.
In a further embodiment, the explosive composition is mixed with an explosive composition selected from the group consisting of ammonium nitrate and fuel oil mixtures (ANFO), emulsion explosive compositions, slurry explosive compositions, mixtures of ANFO and emulsion explosive compositions, and mixtures of ANFO and slurry explosive compositions. Slurry explosives are sometimes referred to in the art as water gel explosives.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The present explosive composition comprises a particulate low density agent and a particulate oxidizing agent, each of which have been coated with a wetting agent. The wetting agent comprises a mixture of a flowable carbonaceous fuel and a tackifying agent. The wetting agent for the particulate low density agent may be different from the wetting agent for the particulate oxidizing agent but preferably they are the same.
The low density agent may be any suitable particulate synthetic polymeric low density material. Typically, the density is less than about 0.1 g/cm3. Foamed polystyrene beads, for example, may have a density of between about 0.01 g/cm
3
and 0.05 g/cm
3
. The low density agent, which is particulate, may have particle sizes up to about 5 mm or more and preferably between about 0.5 and 5 mm. The particulate low density agent is preferably selected from the group consisting of synthetic thermoplastic polymer bubbles and expanded synthetic carbonaceous polymers. Typical expanded synthetic carbonaceous polymers are foamed polystyrene, foamed polyurethane, foamed polyolefin and mixtures thereof. Expanded polystyrene is preferred. Foamed or expanded polymers such as polystyrene are commercially available. It is to be noted that the low density agents have been pre-expanded, e.g. expanded polystyrene, and expansion of the agent during manufacture of the explosive composition is not required.
The wetting agent for the particulate low density agent is a flowable carbonaceous fuel and a tackifying agent soluble in the flowable carbonaceous fuel.
The carbonaceous fuel may be a liquid, a syrup or a light wax which can be easily liquefied, and which does not damage the low density structure of the low density agent. For example No. 2 fuel oil or diesel oil may tend to dissolve polys
Baker Aileen J.
Ridout & Maybee
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