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Explosives that are sensitized blends of a water-in-oil emulsion and inorganic nitrate, e.g., AN, particles, such as AN or ANFO prills, have improved stability when their structure hinders the loss of water from the aqueous emulsion phase and transportation of such water across the oil phase to the

Explosives that are sensitized blends of a water-in-oil emulsion and inorganic nitrate, e.g., AN, particles, such as AN or ANFO prills, have improved stability when their structure hinders the loss of water from the aqueous emulsion phase and transportation of such water across the oil phase to the nitrate particles. Use of an anionic emulsifying agent comprising a fatty acid salt, e.g., as formed in situ during the formation of the emulsion, is the preferred way of forming such a blend-stabilizing structure. Emulsion/nitrate blends stabilized in this manner make satisfactory storage-stable packaged products. Emulsion/nitrate blends made with a new low-viscosity emulsion containing essentially all of the oil required to oxygen-balance the blend and a proportionately larger amount of anionic emulsifying agent to stabilize the emulsion structure constitute preferred bulk products owing to their greater adaptability to pumping. Pumping the stabilized blends through an annular stream of aqueous lubricating liquid is advantageous.

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1. In a method of preparing an explosive composition by combining inorganic nitrate particles with a water-in-oil emulsion comprising (a) a liquid carbonaceous fuel having components which form a continuous emulsion phase, (b) an aqueous solution of an inorganic oxidizing salt forming a discontinuou

1. In a method of preparing an explosive composition by combining inorganic nitrate particles with a water-in-oil emulsion comprising (a) a liquid carbonaceous fuel having components which form a continuous emulsion phase, (b) an aqueous solution of an inorganic oxidizing salt forming a discontinuous emulsion phase dispersed at discrete droplets within said continuous phase, and (c) an emulsifying agent to form a blend of said particles and said emulsion containing a sensitizing amount of dispersed gas bubbles or voids, the improvement comprising forming said inorganic nitrate particles and the components of said emulsion into a structure that minimizes the loss of water from said droplets and transportation thereof across said continuous oil phase to said nitrate particles. 2. A method of claim 1 wherein said structure is formed by combining said inorganic nitrate particles with an emulsion which contains, in its emulsifying system, a salt of a fatty acid, as well as the free fatty acid in solution in an oil, said oil solution forming said continuous emulsion phase, and said fatty acid, said fatty acid salt, and said oil together forming said liquid carbonaceous fuel. 3. A method of claim 2 wherein the inorganic nitrate particles combined with said emulsion to form said blend are air-carrying prills, and the emulsion combined with said prills is devoid of a sensitizing amount of dispersed gas bubbles or voids. 4. A method of claim 3 wherein the prills used to form said blend are ANFO prills, and the emulsion used is essentially oxygen-balanced. 5. A method of claim 1 wherein said structure is formed by mixing said particles with an emulsion which has been formed by mixing said liquid carbonaceous fuel and said aqueous salt solution at a rate and for a time sufficient to produce a cell size of said discontinuous emulsion phase in the range of about from 1 to 4 microns. 6. A method of claim 1 wherein said structure is formed by coating said particles with an agent in which water has a diffusion coefficient at 25° C. of less than about 10 -5 cm 2 /sec. 7. A method of claim 1 wherein said inorganic nitrate particles are AN prills, ANFO prills, or a combination thereof. 8. A method of claim 1 wherein said blend is formed and thereafter packaged. 9. A method of claim 8 wherein said emulsion, when aged at 25° C. for 2 days, loses no more than about 4 percent of its original weight when subjected to the following Water Diffusion Test: filling a cylindrical pan of 7.5 mm radius and 2.6 mm height with 0.325 cc of freshly prepared emulsion, contacting the emulsion's flat exposed surface of 1.25 cm 2 area with a cylindrical pellet of an inorganic nitrate having the same cross-sectional area as the emulsion sample and a height of at least 1 cm, and storing the emulsion/nitrate sample for 48 hours in dry air at 25° C., after which time the emulsion is analyzed for water loss. 10. A method of claim 8 wherein said structure is formed by combining said nitrate particles with an emulsion which contains, in its emulsifying system, a salt of a fatty acid, as well as the free fatty acid in solution in an oil, said oil solution forming said continuous emulsion phase, and said fatty acid, said fatty acid salt, and said oil together forming said liquid carbonaceous fuel. 11. A method of claim 10 wherein said fatty acid is selected from the group consisting of saturated and mono-, di-, and tri-unsaturated monocarboxylic acids containing about from 12 to 22 carbon atoms, and said salt is an alkali metal, ammonium, and/or alkylammonium salt. 12. A method of claim 10 wherein said structure is formed by combining said nitrate particles with an emulsion that has been obtained by combining said oil and said aqueous solution with agitation in the presence of said fatty acid and a base so as to form said fatty acid salt emulsifying agent in situ. 13. A method of claim 8 wherein said structure is formed by mixing said particles with an emulsion which has been formed by mixing said liquid carbonaceous fuel and said aqueous salt solution at a rate and for a time sufficient to produce a cell size of said discontinuous emulsion phase in the range of about from 1 to 4 microns. 14. A method of claim 8 wherein said structure is formed by coating said particles with an agent in which water has a diffusion coefficient at 25° C. of less than about 10 -5 cm 2 /sec. 15. A method of claim 10 wherein said particles constitute at least about 20 percent, and said emulsion constitutes at least about 20 percent, by weight of said blend. 16. A method of claim 10 wherein said inorganic nitrate particles are AN prills, ANFO prills, or a combination thereof. 17. In a method of preparing an explosive composition by combining inorganic nitrate particles with a water-in-oil emulsion comprising (a) a liquid carbonaceous fuel having components which form a continuous emulsion phase, (b) an aqueous solution of an inorganic oxidizing salt forming a discontinuous emulsion phase dispersed as discrete droplets within said continuous phase, and (c) an emulsifying agent to form a blend of said particles and said emulsion containing a sensitizing amount of dispersed gas bubbles or voids, the improvement comprising combining inorganic nitrate prills with an emulsion which contains liquid carbonaceous fuel in an amount sufficient to essentially oxygen-balance said prills and said inorganic oxidizing salt present in said aqueous solution, said emulsion containing, in its emulsifying system, a salt of a fatty acid, as well as the free fatty acid in solution in an oil, said oil solution forming said continuous emulsion phase, and said fatty acid, said fatty acid salt, and said oil together forming said liquid carbonaceous fuel. 18. A method of claim 17 wherein said fatty acid is selected from the group consisting of saturated and mono-, di-, and tri-unsaturated monocarboxylic acids containing about from 12 to 22 carbon atoms, and said salt is an alkali metal, ammonium, and/or alkylammonium salt. 19. A method of claim 18 wherein said structure is formed by combining said nitrate prills with an emulsion that has been obtained by combining said oil and said aqueous solution with agitation in the presence of a fatty acid and a base so as to form a fatty acid salt emulsifying agent in situ. 20. A method of claim 19 wherein the amount of liquid carbonaceous fuel in said emulsion is about from 7 to 21 percent, based on the weight of said emulsion. 21. A method of claim 20 wherein the amounts of fatty acid and base added to form said fatty acid salt in situ are sufficient that the ratio of the amount of oil added to the amount of fatty acid added is in the range of about from 1/1 to 3/1 by weight, and the equivalents ratio of the amount of base added to the amount of fatty acid added is in the range of about from 0.5/1 to 3/1. 22. A method of claim 21 wherein said fatty acid is oleic acid, and said fatty acid salt is ammonium oleate and/or one or more alkali metal salts of oleic acid. 23. A method of claim 17 wherein said blend is formed from an emulsion that is devoid of a sensitizing amount of dispersed gas bubbles or voids. 24. A method of claim 17 wherein supplemental air-carrying solid materials are combined with said prills and emulsion. 25. A method of claim 17 wherein said prills are AN prills. 26. A method of claim 25 wherein said AN prills constitute about from 20 to 70 percent by weight of said blend. 27. A water-in-oil emulsion adapted to be blended with inorganic nitrate prills to form an explosive, said emulsion comprising (a) about from 7 to 21 percent by weight of a liquid carbonaceous fuel including an oil solution of a fatty acid, said solution forming a continuous emulsion phase; (b) an aqueous solution of an inorganic oxidizing salt forming a discontinuous emulsion phase dispersed as discrete droplets within said continuous phase; and (c) an emulsifying system comprising (1) said fatty acid and (2) a fatty acid salt, said oil, fatty acid, and fatty acid salt together forming said liquid carbonaceous fuel, and the ratio of the amounts of oil and fatty acid added to form said emulsion being in the range of about from 1/1 to 3/1 by weight; said emulsion having an oxygen balance more negative than about -6 percent. 28. An emulsion of claim 27 wherein said emulsifying system is one which forms in situ from a fatty acid and a base as said oil and said aqueous solution are brought together to form said emulsion, the ratio of the amount of base added to the amount of fatty acid added to form said emulsifying system being about from 0.5/1 to 3/1 by weight. 29. An emulsion of claim 28 having a viscosity in the range of about from 500 to 10,000 poise, and stable in emulsion structure for a period of at least about 3 months. 30. An emulsion of claim 27 wherein said emulsifying system is formed by adding a fatty acid and a salt of a fatty acid to the other components of the emulsion, said ratio of oil to "fatty acid" being understood to be the ratio of oil to fatty acid plus fatty acid salt added when the emulsion is being made, and the ratio of said fatty acid salt added to fatty acid added being at least about 0.5/1. 31. An emulsion of claim 27 wherein said fatty acid salt is selected from alkali metal, ammonium, and alkylammonium salts of saturated and mono-, di-, and tri-unsaturated monocarboxylic acids containing about from 13 to 22 carbon atoms. 32. An emulsion of claim 31 wherein said fatty acid is oleic acid, and said fatty acid salt is ammonium oleate and/or one or more alkali metal salts of oleic acid. 33. An emulsion of claim 27 containing dispersed air-carrying inert solid materials. 34. An emulsion of claim 27 devoid of a sensitizing amount of dispersed gas bubbles or voids. 35. An essentially oxygen-balanced water-in-oil emulsion adapted to be blended with inorganic nitrate prills and oil to form an explosive, said emulsion comprising (a) a liquid carbonaceous fuel including an oil solution of a fatty acid, said solution forming a continuous emulsion phase; (b) an aqueous solution of an inorganic oxidizing salt forming a discontinuous emulsion phase dispersed as discrete droplets within said continuous phase; and (c) an emulsifying system comprising (1) said fatty acid and (2) a fatty acid salt, said oil, fatty acid, and fatty acid salt together forming said liquid carbonaceous fuel; said emulsion being devoid of a sensitizing amount of dispersed gas bubbles or voids. 36. An emulsion of claim 35 wherein said prills and oil with which said emulsion is adapted to be blended are AN prills mixed with fuel oil. 37. An explosive product comprising a blend of about from 30 to 80 percent by weight of the emulsion of claim 27 and about from 70 to 20 percent by weight of inorganic nitrate prills sufficient to essentially oxygen balance said emulsion, said blend containing a sensitizing amount of dispersed gas bubbles or voids. 38. An explosive product comprising a blend of about from 50 to 80 percent by weight of the emulsion of claim 28 and about from 50 to 20 percent by weight of ammonium nitrate prills sufficient to essentially oxygen balance said emulsion, said blend containing a sensitizing amount of dispersed gas bubbles or voids, having a viscosity in the range of about from 2500 to 20,000 poise, and remaining in said range for a period of several days. 39. An explosive product of claim 37 wherein said dispersed gas is the gas present in said ammonium nitrate prills. 40. An explosive product of claim 37 wherein supplemental air-carrying solid materials are present. 41. An explosive product of claim 37 wherein the prill content is about from 40 to 60 percent by weight, and the liquid carbonaceous fuel content of said emulsion is about from 9 to 15 percent by weight. 42. A method of delivering the explosive product of claim 38 to a borehole through a conduit comprising pumping said product to the borehole through an annular stream of aqueous lubricating liquid flowing through the conduit in the same direction as the explosive product, said product being adapted to resume flowing when pumping is resumed after extended periods of rest in said conduit, independently of the composition of said aqueous lubricating liquid. 43. A method of claim 42 wherein said aqueous lubricating liquid is naturally occurring water. 44. An aged, storage-stable explosive product comprising, in a package, a blend of particles of ammonium nitrate (AN) and an emulsion comprising (a) a liquid carbonaceous fuel including an oil solution of a fatty acid, said solution forming a continuous emulsion phase, (b) an aqueous solution of an inorganic oxidizing salt forming a discontinuous emulsion phase dispersed as discrete droplets within the continuous phase, and (c) an emulsifying system including an emulsifying agent comprising (1) an alkali metal, ammonium, or alkylammonium salt of a fatty acid containing about from 12 to 22 carbon atoms, as well as (2) the free fatty acid, said fatty acid, said fatty acid salt, and said oil together forming said liquid carbonaceous fuel, and said blend containing dispersed gas bubbles or voids comprising at least about 5 percent of its volume, said emulsion, when aged at 25° C. for 2 days, losing no more than about 4 percent of its original weight when subjected to the following Water Diffusion Test: filling a cylindrical pan of 7.5 mm radius and 2.6 mm height with 0.325 cc of freshly prepared emulsion, contacting the emulsion's flat exposed surface of 1.25 cm 2 area with a cylindrical pellet of ammonium nitrate having the same cross-sectional area as the emulsion sample and a height of at least 1 cm, and storing the emulsion/AN sample for 48 hours in dry air at 25° C., after which time the emulsion is analyzed for water loss. 45. An explosive product of claim 44 wherein said emulsion has been obtained by combining said aqueous solution and an oil with agitation in the presence of a fatty acid and a base so as to form said fatty acid salt in situ, said emulsifying system also containing base. 46. An explosive product of claim 45 wherein said AN particles constitute at least about 20 percent, and said emulsion constitutes at least about 20 percent, of said blend by weight. 47. An explosive product comprising a blend of inorganic nitrate prills and an emulsion comprising (a) a liquid carbonaceous fuel having components which form a continuous emulsion phase, (b) an aqueous solution of an inorganic oxidizing salt forming a discontinuous emulsion phase dispersed as discrete droplets within the continuous phase, and (c) an emulsifying system including an emulsifying agent comprising a salt of a fatty acid, as well as the free fatty acid in solution in an oil, said oil solution forming said continuous emulsion phase, and said fatty acid, said fatty acid salt, and said oil together forming said liquid carbonaceous fuel, said blend containing a sensitizing amount of dispersed gas essentially provided by said prills. 48. An explosive product of claim 47 wherein said prills are AN prills which constitute about from 20 to 80 percent by weight of said blend. 49. An explosive product of claim 48 wherein the ammonium nitrate prills used to form the blend are ANFO prills, and the emulsion used is an essentially oxygen-balanced emulsion. 50. A method of claim 1 wherein a substantially hydrophobic medium is present between said inorganic nitrate particles and the aqueous droplets in said emulsion. 51. A method of claim 1 wherein said emulsion, when aged at 25° C. for 2 days, loses no more than about 4 percent of its original weight when subjected to the following Water Diffusion Test: filling a cylindrical pan of 7.5 mm radius and 2.6 mm height with 0.325 cc of freshly prepared emulsion, contacting the emulsion's flat exposed surface of 1.25 cm 2 area with a cylindrical pellet of an inorganic nitrate having the same cross-sectional area as the emulsion sample and a height of at least 1 cm, and storing the emulsion/nitrate sample for 48 hours in dry air at 25° C., after which time the emulsion is analyzed for water loss. 52. A method of claim 1 wherein said emulsion constitutes about from 10 to 90 percent, and said particles about from 90 to 10 percent, by weight of said blend. 53. A method of claim 9 wherein said emulsion constitutes about from 10 to 90 percent, and said particles about from 90 to 10 percent, by weight of said blend. 54. A method of claim 17 wherein said emulsion constitutes about from 10 to 90 percent, and said prills about from 90 to 10 percent, by weight of said blend. 55. A method of claim 51 wherein said emulsion constitutes about from 10 to 90 percent, and said particles about from 90 to 10 percent, by weight of said blend. 56. An explosive product of claim 44 wherein said emulsion constitutes about from 10 to 90 percent, and said particles about from 90 to 10 percent, by weight of said blend.