Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B47/00—Compositions in which the components are separately stored until the moment of burning or explosion, e.g. "Sprengel"-type explosives; Suspensions of solid component in a normally non-explosive liquid phase, including a thickened aqueous phase
  • C06B47/14—Compositions in which the components are separately stored until the moment of burning or explosion, e.g. "Sprengel"-type explosives; Suspensions of solid component in a normally non-explosive liquid phase, including a thickened aqueous phase comprising a solid component and an aqueous phase

Definitions

• the present invention relates to an improved blasting agent composition. It has particular application to low eost explosives which are water plasticized or liquefied, i.e.,
• inorganic nitrates preferably ammonium nitrate or am- :monium nitrate with sodium nitrate, modified, e.g. by adding a suitable fuel or other material.
• the inorganic nitrate which is usually the largest component, generally is not sufiiciently sensitive per se for mining and blasting operations. Moreover, it is primarily an oxidizer and requires addition of fuel or a reducer for good chemical balance.
• Various compositions have been made up to improve the performance of the basic inorganic nitrate ingredient. In some cases, it has previously been suggested, sodium nitrate may be used to replace part of the ammonium nitrate.
• ni- Irated organic materials such as cellulose nitrate (smokeless powder) trinitrotoluene (TNT), nitromethane and the like, reducingmetals such as powdered aluminum, and fuels such as sulfur, carbonaceous materials, hydrocarbons, etc.
• TNT cellulose nitrate
• reducingmetals such as powdered aluminum
• fuels such as sulfur, carbonaceous materials, hydrocarbons, etc.
• the most effective and satisfactory sensitizers have been the explosive or nitrated organic additives such as TNT, picric acid, intro-starch, smokeless powder and the like. These materials contribute energy as well as improving the sensitivity of ammonium nitrate. However, these explosive materials always involve certain hazards in handling and processing.
• sensitizers Some of the materials named above as sensitizers are commonly employed in finely divided form and they often .tend to accumulate in pockets, hidden recesses and the ore in quantity, the blasting agent must be sensitive enough for thorough detonation at the borehole temperature, in columns of conventional diameter (usually around 6 to 9 inches, although smaller and larger diameter bores are used) and in lengths several times their diameter. Borehole temperatures may vary from about C. to 30 C.. depending upon geographical location, primarily. At
• the blasting agent should not be so sensitive as to involve any substantial risk of explosion during normal shipping, handling, or while putting it in the borehole for use.
• mechanical means e.g., by slurry mixing and pumping machinery or by mixing and packaging equipment.
• the slurry composition must not be sensitive enough to explode in small masses when subjected to moderate friction or shock of the character inherent in operation of such machinery.
• the slurry when finished and ready for detonation, should have a sensitivity suitable for its selfpropagation of explosion in a continuous column, e.g. six diameters in length or more and not more than 9 or 10 inches in diameter, unconfined, at the borehole temperature.
• the explosive For far northern areas, or shallow operations in winter time, the explosive must be detonable at temperatures as low as 5 C. In other cases, the explosive need be detonable at temperatures as high as 35 C. Sensitivity must not be too great, however, and a critical diameter of about 1 /2 to 2 inches is usually the lower working limit, at working temperatures. A 6-inch diameter column gives good general test results.
• a specific object of the present invention is to prepare a slurry type blasting agent, based primarily on ammonium nitrate, but also containing sodium nitrate, which will meet the above sensitivity tests both minimum and maximum and still not necessarily contain any of the more hazardous sensitizers such as the nitrated organic materials which are normally explosive per se.
• An important aspect of this invention is the discovery that by using well chosen proportions of sulfur, along with sodium nitrate, the sensitivity of high ammonium nitrate explosives, particularly those containing water, may be controlled very satisfactorily.
• high ammonium nitrate it is intended to mean those compositions which contain 40% by weight or more, preferably at least 50%, of ammonium nitrate.
• the sulfur is preferably related to the sodium nitrate, in proportion, preferably being between 10 and 30% of the weight of sodium nitrate, proportions of about 1 to 5 being especially preferred.
• the explosive composition have as high a density as possible, consistent with other necessary qualities or properties.
• increased density permits the use of a greater weight of blasting agent in a borehole of given dimensions.
• increasing the density of a given composition normally also tends to decrease sensitivity, particularly in slurry-type or water plasticized blasting agents.
• a further object of this invention is to make a blasting composition of optimum or near optimum density which has also the properties of optimum or near optimum sensitivity, together with adequate power, appropriate brisance, etc.
• a preferred general composition comprises a thick aqueous slurry containing a larger proportion of ammonium nitrate in solution and including at least a small amount of sodium nitrate. From about 40 to 70% by weight of ammonium nitrate is used. The preferred range of ammonium nitrate is about 50 to 60%. Water content, or rather liquid content, since some of the water may be replacedwith a compatible liquid fuel such as ethylene glycol, glycerine, or other lower aliphatic alcohols, should be between about 10 and 20% by weight of the total composition. Preferably the liquid is usually between 12 and 16%.
• Proportions totaling from about to 25% by weight of sodium nitrate are preferably included in addition to the ammonium nitrate. It is desirable that at least a part of the sodium nitrate ingredient be dissolved in the liquid.
• the addition of sodium nitrate makes it possible to increase the total inorganic nitrate salt content of a saturated solution at a given temperature. It also makes it possible, when sulfur is included too, to sensitize the inorganic nitrates directly. Apparently, the presence of sulfur makes it possible to convert the sodium nitrate to sodium sulfate. This releases more energy than does the reaction which results when sulfur is not present. In providing an easier route for the chemical breakdown of the sodium nitrate, the whole composition is sensitized.
• additional sodium nitrate beyond that which can be dissolved may be and preferably is used.
• Sodium nitrate in this form not only adds to the oxidizer total content but also contributes to sensitivity of the slurry in conjunction with sulfur.
• Sulfur also has fuel value and tends to improve the oxygen balance in high inorganic nitrate compositions.
• Proportions preferred are between 1 and 6 percent by weight, preferably 2 to 5%.
• a thickener In order to produce an explosive slurry which will thicken on standing in the boreholeand in order also to reduce water loss and to resist dilution of the composition by ground water which may be present in the hole, a thickener is generally required. For this purpose a small amount of guar gum, from 0.1 to 2% by weight is preferred. However, the guar gum may be replaced in part by other thickeners if desired. Starch has less thickening capacity but is usually satisfactory for this purpose since it also has some fuel value, in addition to its thickening properties, in water solutions or slurries.
• dry fuel materials may be added to the extent required for good oxygen balance and consistent with the slurry properties desired.
• Materials such as gilsonite, or other heavy and preferably solid carbon or hydrocarbon residues that can be comminuted, such as hard asphalt, bituminous coal, finely divided carbon, and charcoal may be used.
• Dry starch above the quantity that can be taken up by the liquid in the slurry, also is a desirable ingredient in some cases. The total of such dry fuels may vary from about 5 to 15% of the weight of the finished composition, preferably between about 7 and 12%.
• An optional but usually highly desirable ingredient is aluminum powder. It is an effective sensitizer, as noted above. Moreover, it contributes considerable energy as a fuel. Proportions of /z% to 3% or more of aluminum by weight, based on the total composition, may be used.
• the density of a slurry blasting composition should not exceed about 1.4 grams per ,cc.
• Example 1 A composition was prepared by dissolving 54 parts by weight of ammonium nitrate in 13 /2 parts ofwater at 60 C. temperature. To this were added about 9 parts of sodium nitrateabout all that wouild go into solution. A further quantity of 10 parts of dry granular sodium nitrate, which did not dissolve, was added thereafter, 19 parts in all.
• Example 2 A composition similar to that of Example 1 was prepared except that 10 parts of water and 5 parts of ethylene glycol were used instead of 13 /2 parts of water. Results were essentially the same as in Example 1, so far as sensitivity is concerned.
• the compositions of both Examples 1 and 2 were apparently very nearly equal in energy to slurries of ammonium nitrate sensitized with TNT. They are appreciably less expensive.
• the composition will contain enough liquid to make it flow freely as a quasi-liquid, for most applications.
• This liquid may be all water, or
• water compatible liquids of various types, such as alcohols, glycols and oxygen derivatives of hydrocarbons in general.
• terials e.g. molasses, may be included.
• proportions of sodium nitrate and sulfur may be varied from 5 to 25% by weight of the former and about 1 to 8% of the latter.
• excess oxygen from the principal inorganic nitrate component may be balanced as fully as desired by use of other fuel components as described above.
• a moisture-containing explosive composition which contains from about 5 to percent by weight of a moistening liquid, the major part of which liquid is water, 40 to 70 percent of ammonium nitrate, and a sensitizer comprised of 2 to 25 percent of sodium nitrate and 1 to 8 percent of elemental sulfur, based on the total composition.
• Aqueous solutions of fuel ma- 2. A composition according to claim 1 to which is added 0.5 to 3 parts of aluminum powder below about mesh particle size as an additional fuel and sensitizer.
• Composition according to claim 1 which contains 0.1 to 2 percent of a slurry thickener.
• composition according to claim 4 wherein the thickener is guar gum.
• composition accordingto claim 1 which contains 12 to 20 percent of the liquid.
• Composition according to claim 6 which also contains a carbohydrate fuel.
• composition according to claim-1 which also includes a carbohydrate fuel.
• a slurry explosive composition which contains sufficient liquid to make it flow freely as a quasi-liquid, at least the major proportion of said liquid being Water, at least 50 percent by Weight of ammonium nitrate, 2 to 25 percent of sodium nitrate, and about one-fifth as much sulfur as sodium nitrate, by weight, whereby the sodium nitrate and the sulfur tend to sensitize the ammonium nitrate.
• composition according to claim 9 wherein at least a part of the sodium nitrate is not in solution.
• composition according to claim 10 wherein undissolved sodium nitrate and sulfur are intimately mixed to form an effective sensitizer.
• composition according to claim 10 which also contains not more than 3 percent by weight of finely divided aluminum.
• a slurry explosive blasting composition comprising a saturated solution of an inorganic nitrate selected from the group which consists of ammonium nitrate and ammonium nitrate mixed with a minor proportion of sodium nitrate, said inorganic nitrate comprising at least half the total weight of the composition, a quantity of und issolved particulate sodium nitrate, about one-fifth as much sulfur as total sodium nitrate, not more than 10% of particulate metallic aluminum, and a thickening agent in suflicient proportions to reduce penetration of said slurry by ground water.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Liquid Carbonaceous Fuels (AREA)

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Cited By (9)

Citations (1)

• 1964
  • 1964-05-01 US US364289A patent/US3249477A/en not_active Expired - Lifetime
• 1965
  • 1965-04-29 OA OA51652A patent/OA01703A/fr unknown

Patent Citations (1)

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