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
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S149/00—Explosive and thermic compositions or charges
  • Y10S149/11—Particle size of a component
  • Y10S149/115—Organic fuel

Definitions

• Aqueous blasting agents containing an immiscible liquid hydrocarbon fuel are formulated by prethickening the liquid phase of the composition by the addition of a thickening agent, preferably a biopolymer gum, thereafter adding the liquid fuel and subsequently mixing the combination so as to form a stable, fine dispersion of immiscible liquid hydrocarbon fuel droplets throughout the liquid phase.
• a thickening agent preferably a biopolymer gum
• an immiscible liquid fuel-in order to provide more economical explosive compositions by eliminating the metal sensitizer (e.g., aluminum) or high explosive sensitizer (e.g., trinitrotoluene)-compositions in various forms including aqueous slurries comprising essentially AN (or AN/sodium nitrate (SN) combinations), immiscible liquid fuel such as fuel oil, and Water have been suggested but these latter compositions have not detonated satisfactorily in dry or water-containing boreholes except by use of multiple boosters at high booster/ slurry weight ratios, e.g., l/25 or higher.
• metal sensitizer e.g., aluminum
• high explosive sensitizer e.g., trinitrotoluene
• immiscible liquid fuel such as fuel oil
• Water have been suggested but these latter compositions have not detonated satisfactorily in dry or water-containing boreholes except by use of multiple boosters at high booster/ slurry weight
• compositions of this invention are relatively sensitive to detonation without requiring metal or high explosive sensitizers or the use of high booster/ slurry weight ratios or multiple boostering and therefore are very economical.
• a slurry or aqueous blasting composition comprising an aqueous solution containing an oxidizing salt or salts, such as AN, CN, or SN or other oxidizers, and an immiscible hydrocarbon liquid fuel, such as fuel oil, can be efficaciously formulated in such a manner that a fine dispersion of the liquid fuel is effected and maintained throughout the composition by proper thickening and mixing procedures and, preferably, by the use of a small amount of a biopolymer or other similar functioning gum as the thickening agent or part thereof.
• the essential ingredients for forming the explosive compositions of the present invention are an inorganic oxidiing salt or salts present in amount from about 60% to about by weight of the total composition; sulficient water at least about 10% by weight, to form a pump able composition at the preparation or mixing temperature an immiscible liquid hydrocarbon fuel; and a thickening agent or agents.
• the immiscible liquid hydrocarbon fuel is the primary fuel and is incorporated into a prethickened salt solution in the final form of a uniform and homogeneous dispersion of discrete liquid droplets.
• the dispersed liquid particles are approximately .025 cm. or smaller in diameter which, because of the effect of the thickening agent, do not rapidly separate out of or coalesce in the medium in which such particles are suspended.
• the immiscible hydrocarbon fuels can be aliphatic, alicyclic, and/or aromatic. Suitable fuels can be either saturated and/ or unsaturated, For example, benzene, toluene, and the xylenes can be employed. Preferred fuels include mixtures of normally liquid hydrocarbons generally referred to as petroleum distillates such as gasoline, kerosense, and diesel fuels. A particularly preferred liquid fuel is No. 2 fuel oil. Tall oil and paraffin oil can also be used. The liquid fuel is preferably present in amount of about 4% to about 12% by weight.
• the immiscible liquid fuel be introduced into an aqueous solution of the oxidizing salt(s), which has been prethiokened to a predetermined viscosity in order to effect the fine dispersion.
• a thickening agent or agents or prethickening the solution can have important effects on the ease of forming and maintaining this dispersion.
• a preferred type of thickening agent for this purpose is a biopolymer gum produced by a process comprising the microbial transformation of carbohydrate material; for example, such as by transforming a carbohydrate with a microorganism to obtain a polymeric material differing in form and substance from the parent material.
• Suitable carbohydrates include sugars, such as pentoses or hexoses (for example, glucose, sucrose, fructose, maltose, lactose, galactose), and starches, such as soluble starch, corn starch, and the like. Unrefined carbohydrates may be used.
• Microorganisms suitable for effecting the microbial transformation of carbohydrates may be, for example, plant pathogenic bacteria such as plant pathogens which produce exudates at the site of lesions on infected plants. Typical of such microorganisms are the species of the genus Xanthomonas.
• the excellular bacterial polysaccharides produced biochemically with Xanthomonas campestris from simple sugar nutrients such as glucose are composed of D-glucose, D-mannose, and D-glucuronic acid in a ratio of 2.8/ 3.0/2.0.
• Acetic and pyruvic acid substitutes are present in amounts of about 4.7% and 3.0% to 3.5%, respectively.
• acetic acid exists as the O-acetyl ester, Whereas pyruvic acid is attached through a ketal linkage.
• Biopolymers may also be produced from similar organisms other than those of the genus Xanthomonas.
• gums that are not of the biopolymer type which are also preferred over more conventional gums since they are functionally similar to the biopolymer gums.
• These gums are generally alkyl substituted guar gums such as General Mills GenGel E2, Stein Hall 4763, and General Mills XG-498.
• Biopolymer or these other specific alkyl substituted gums are more effective on a concentration basis in forming and maintaining a fine dispersion of an immiscible liquid hydrocarbon fuel throughout an aqueous blasting composition than other conventional types of thickening agents, such as regular guar gums and starches. This effectiveness is probably due to a unique droplet entrapping network that is formed upon hydration of these gums in an aqueous solution.
• a preferred biopolymer gum for use as a thickening agent in explosive compositions of the present invention is General Mills XE-23 which is available commercially and produced from a carbohydrate which has been exposed to Xanthomonas campestris. This particular biopolymer has been used heretofore in other slurry explosive compositions as a thickening agent and was found to be a highly effective and stable thickener, particularly at high temperatures and over extended periods of time and wide pH ranges (see for example commonly assigned US. Pat. 3,658,607). XE-23 and other thickening agents of a similar nature have certain key physical properties which enables them to be used effectively with an immiscible hydrocarbon liquid fuel, particularly in forming a fine dispersion of fuel droplets.
• the biopolymer XB-23 functions as a thickener of an aqueous solution of an explosive composition in the ordinary sense; i.e., it is similar to commonly used guar gum which swells upon hydration to thicken or increase the viscosity of the solution. However, its chemical nature is such that it, unlike guar gum, can be considered to be noncross-linking in the presence of conventional crosslinkers such as chromate ion. Aside from being an efficient thickener in terms of viscosity versus concentration as well as being very stable over a wide pH and temperature range, XB23 or similar biopolymers as described above exhibit two additional properties that make them exceptional for use in slurry explosive compositions containing an immiscible liquid hydrocarbon fuel:
• the polymeric gum molecules interact with one another to form a unique entrapping network.
• the liquid fuel is formed and maintained in a finely dispersed state.
• the gums impart a thixotropic nature to the thickened salt solution.
• the gums by exhibiting decreased viscosity with increased shear, allow relatively easy dispersion of the liquid fuel when the solution and liquid fuel are subjected to the action of a mixing blade.
• the viscosity of the solution rises sharply thereby apparently entrapping or encapsulating the liquid droplets in their dispersed state.
• non-thixotropic thickening agents When non-thixotropic thickening agents are used, the viscosity of the solution at the time of mixing and pumping must be higher in order to assure permanency of the final dispersion and composition and good initial water resistance. Therefore, ease of handling the compositions is decreased somewhat when nonthixotropic thickening agents are used. Furthermore, biopolymer gums do not require rapid cross-linking for permanency and effectiveness. Rapid cross-linking is necessary for maintaining a permanent, stable dispersion when most conventional non-thixotropic thickening agents are used, and use of these latter agents makes the time coordination of mixing and pumping or delivery more critical.
• the total thickening agent is generally present in amounts of from about 0.05% to about 0.50% of which preferably about 0.1% is a biopolymer gum.
• One or more conventional cross-linkable thickening agents are preferably employed in the course of preparing the explosive compositions of the present invention to supplement the thickening function of the preferred biopolymer gums in regulating the viscosity of the composition so as to permit pumping of compositions containing finely divided sensitizing gas bubbles, to prevent any substantial segregation and/ or coalescence of the ingredients, and to improve the water resistance of the composition.
• Conventional cross-linkable thickening agents which are known in the art include guar gums, starches, and synthetic polymeric products. It is also economically desirable to replace some of the biopolymer gums with these cross-linkable thickening agents since the biopolymer gums are relatively more expensive.
• a density-lowering or gassing agent such as sodium nitrite to lower the density of the composition to a predetermined degree
• a crosslinking agent to eflfect the gelation of any cross-linkable thickening agent.
• gassing agents such as sodium nitrite and hydrogen peroxide have been employed heretofore to lower the density and thereby, in part, control the sensitivity of explosive slurry compositions.
• the compositions of the present invention preferably employ a small amount, e.g., about 0.01% to about 0.2% or more (most preferably about 0.05%), of such gassing agent in order to obtain a density under service conditions of less than about 1.5 gm./cc.
• Cross'linking agents in combination with suitable crosslinkable thickening agents are also preferably employed in order to further stabilize the fine dispersion or distribution of the droplets or particles of liquid hydrocarbon fuel, as well as to prevent the undesired escape of gas bubbles, and thus maintain the sensitivity to detonation resulting from the fine dispersion.
• Cross-linking agents are also especially useful where the stability or integrity of the composition must be maintained in the presence of water-containing boreholes.
• Excellent cross-linking of guar gum can be obtained by using a small amount, e.g., about 0.05% to about 0.2%, of an aqueous solution of sodium dichromate.
• Other cross-linking systems will also be apparent to those skilled in the art.
• supplemental solid fuels such as particulate aluminum, magnesium alloys, sulfur, and normally solid hydrocarbons such as wheat and other vegetable grain, starch, etc., and the like may be added to increase the strength and/or sensitivity of the compositions.
• Starches and vegetable grains can be added in amounts up to about 15% by weight and can function as fuel, sensitizer, and thickener combined, as disclosed in commonly assigned U.S. application Ser. No. 309,177. If starches or grains are added they can function either primarily or secondarily as sensitizer and thickener in compositions of the present invention and as a secondary fuel, being supplemental to the primary immiscible liquid hydrocarbon fuel.
• Thiourea may also be employed in very small amounts, e.g., about 0.05%, to control the rate at which sodium nitrite gassing agent functions ethylene glycol, formamide, and other mutually water-soluble ingredients may also be included in varying amounts.
• the method of preparation of the explosive compositions of the present invention comprises finely dispersing or distributing a liquid hydrocarbon fuel in an aqueous oxidizer salt solution to which a thickening agent has been previously added.
• the oxidizer salt (or salts) is dissolved in water to form a solution of fudge point around 50 C.
• the solution is heated to about 60 C. or 70 C. prior to mixing. Further temperature control is not necessary during mixing.
• Water soluble liquid fuels, if any, may also be added at this juncture.
• a small amount of a thickening agent or agents is next added, thereby thickening the solution to the desired degree. It is preferred that the composition be crosslinked for extended storage stability and increased water resistance and therefore at least part of the thickening agent is preferably cross-linkable.
• the predetermined solution viscosity of the thickened solution should preferably be above about 600 centipoise since at lower viscosities the liquid fuel will tend to coalesce, and initial water resistance of the delivered composition will be impaired.
• a common viscosity would be about 800 centipoises.
• the immiscible liquid hydrocarbon fuel in a conventional manner such as by metering through a positive displacement pump, dribbling, or squirting the liquid hydrocarbon into the thickened solution or by injecting it under pressure through a nozzle which helps to initially break up the liquid into small droplets.
• the cross-linking agent such as sodium dichromate is added (if used) as well as the gassing agent such as sodium nitrite. If thiourea is employed it is generally added to the heated solution prior to the addition of the cross-linking and gassing agents.
• a typical solution thus formed can be represented by the following ratio, parts by Weight: AN 50/H O lS/biopolymer gum 0.1/guar gum 0.2/thiourea 0.1. All other above described, preferred, desirable, and/or optional ingredients can now be simultaneously added. Additionally, dry particulate oxidizer salt may now be added for proper oxygen balance.
• the resulting solution with added ingredients is simply mixed to a desired degree of relative homogeneity and then placed into a container or borehole by appropriate means. It is important that mixing is present and continuous as the liquid hydrocarbon is initially introduced in order that as much mechanical dispersion as possible takes place. The prethickened solution assures that the dispersion will remain fixed and stable after such mixing. Mixing can be accomplished by any conventional equipment known in the art.
• the resulting composition consists essentially of a substantially homogeneous fine dispersion which is gasified to the desired bulk density by stirring in air, for example, or by incorporating a gassing agent.
• compositions As the composition cools some of the oxidizer salt or salts may crystallize out depending upon the temperature reached. If crystallization occurs, the composition will then become firm but pliable. However, with proper thickening (and/or cross-linking) the compositions Will be stable and the liquid fuel will remain properly and uniformly dispersed at temperatures both above and below the crystallization temperature of the salt solution.
• Example I In this example compositions of the present invention having the ingredients and characteristics set forth in Table I were prepared in the manner described above and successfully detonated as indicated in Table I. As shown, tall oil, paraffin, and fuel oil can readily be used for the immiscible liquid hydrocarbon fuel. Composition C shows the use of fine aluminum particles as a supplementary fuel, as a sensitizer, and for added explosive strength. Compositions B through E contain dry particulate AN which was added to the prethickened solution. Composition A had an initial solution viscosity of 920 centipoise at 55 C.
• Thickening agent Stein-Hal1 II-100 guar gum.
• Example II In this example the following composition was prepared:
• This composition had a density of 1.10 gm./cc. at 22 C. It detonated in a 4" diameter at 22 C. with a 3645 m./sec. veloci y and in a 5" diameter at 15 C.
• Example III In this example the following composition was prepared:
• This composition had a density of 0.95 gm./cc. and detonated in a 4" diameter at 20 C.
• the solution viscosity was about 800 centipoise at 65 C. prior to the addition of the fuel oil and dry solid AN.
• Example IV In this example the following solution was prepared:
• Ground whole grain wheat has a particle size distribution of essentially minus 48 Tyler screen.
• a method for forming a stable, explosive blasting composition having an aqueous liquid phase and containing a stable, fine dispersion of a water-immiscible liquid hydrocarbon fuel throughout said aqueous liquid phase without using an oil-in-water emulsifying agent which comprises in combination the following steps:
• a method as recited in claim 1 which comprises the additional step of adding a gassing agent simultaneously with said liquid fuel to gasify said composition to a predetermined density.
• a method as recited in claim 2 which comprises the additional step of adding a gassing agent simultaneously with said liquid fuel to gasify said composition to a pre determined density.
• said thickening agent includes a biopolymer material produced by a process comprising the microbial transformation of carbohydrate material.
• biopolymcr material is produced from Xanthomonas campestris.
• said inorganic oxidizer salt comprises ammonium nitrate and sodium nitrate.
• said immiscible liquid hydrocarbon fuel comprises a petroleum distillate.
• said immiscible liquid hydrocarbon fuel comprises No. 2 fuel oil.
• An aqueous explosive blasting composition free of an oil-in-water emulsifying agent comprising a liquid phase of an aqueous inorganic oxidizer salt solution, a thickening agent for thickening said liquid phase to a predetermined viscosity, and an immiscible liquid hydrocarbon fuel stably and finely dispersed throughout said liquid phase which has been added to said thickened liquid phase.
• An explosive blasting composition free of an oil-inwater emulsifying agent gasified to a predetermined destiny and comprising an aqueous solution of at least one inorganic oxidizer salt, a finely dispersed immiscible liquid hydrocarbon fuel, and a thickening agent at least part of which comprises a biopolymer gum.
• a composition as defined by claim 14 wherein said biopolymer gum is produced from Xanzhomonas campestris.
• composition as defined by claim 14 wherein said immiscible liquid hydrocarbon fuel is No. 2 fuel oil.
• a method for forming a stable, explosive blasting composition having an aqueous liquid phase and containing a stable, fine dispersion of a Water-immiscible liquid hydrocarbon fuel throughout said aqueous liquid phase which consists essentially of a combination of the following steps:
• inorganic oxidizer salt in an aqueous solution at a temperature above the salt crystallization temperature
• An aqueous explosive blasting composition consisting essentially of a liquid phase of an aqueous inorganic oxidizer salt solution, a thickening agent for thickening salt liquid phase to a predetermined viscosity, and an immiscible liquid hydrocarbon fuel stably and finely dispersed throughout said liquid phase which has been added to said thickened liquid phase.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Liquid Carbonaceous Fuels (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Air Bags (AREA)
• Lubricants (AREA)

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Cited By (5)

Families Citing this family (3)

• 1972
  • 1972-11-24 US US00309178A patent/US3788909A/en not_active Expired - Lifetime
• 1973
  • 1973-08-16 CA CA178,995A patent/CA1014355A/en not_active Expired
  • 1973-08-21 ZA ZA735725A patent/ZA735725B/xx unknown
  • 1973-09-06 GB GB4189573A patent/GB1445594A/en not_active Expired
  • 1973-09-06 IN IN2047/CAL/73A patent/IN140456B/en unknown
  • 1973-09-12 AU AU60245/73A patent/AU475550B2/en not_active Expired
  • 1973-09-17 YU YU2458/73A patent/YU36677B/xx unknown
  • 1973-09-24 AT AT820573A patent/AT339799B/de not_active IP Right Cessation
  • 1973-09-25 ZM ZM156/73*UA patent/ZM15673A1/xx unknown
  • 1973-10-12 JP JP48114639A patent/JPS5829279B2/ja not_active Expired
  • 1973-11-22 BR BR9160/73A patent/BR7309160D0/pt unknown
  • 1973-11-23 RO RO7376757A patent/RO65953A/ro unknown
  • 1973-11-23 CH CH1654573A patent/CH587203A5/xx not_active IP Right Cessation
  • 1973-11-23 BE BE138116A patent/BE807744A/xx not_active IP Right Cessation
• 1977
  • 1977-12-30 MY MY178/77A patent/MY7700178A/xx unknown

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