COMPOSITION FOR FORMING AN EXPLOSIVE COMPRISING AN EMULSION OF HYDROGEN PEROXIDE AND AN OIL TYPE FUEL

Abstract

A composition for forming a hydrogen peroxide based emulsion explosive which composition comprises: an oxidizer-phase comprising at least 35% by weight of hydrogen peroxide and at least 25% by weight of water, a fuel-phase comprising at least one primary oil type fuel with a flash point below 100? C. and at least one secondary oil type fuel with a flash point over 150? C. and at least one emulsifier, wherein the oxidizer-phase is discontinuously dispersed throughout the continuous fuel-phase. A method of preparing an emulsion type explosive composition is also disclosed.

Claims

1. A composition for forming a hydrogen peroxide based emulsion explosive which composition comprises; an oxidizer-phase comprising at least 35% by weight of hydrogen peroxide and at least 25% by weight of water, a fuel-phase comprising at least one primary oil type fuel with a flash point below 100? C. and at least one secondary oil type fuel with a flash point over 150? C., and at least one emulsifier, wherein the oxidizer-phase is discontinuously dispersed throughout the continuous fuel-phase.

2. A composition according to claim 1, further comprising a sensitizer, whereby the composition forms a sensitized emulsion explosive.

3. A composition according to claim 2, further comprising a gassing agent which is arranged to form the sensitizer in the form of gas bubbles through a chemical reaction.

4. A composition according to claim 2, wherein the sensitizer comprises mechanically added enclosed hollow microspheres or -balloons.

5. A composition according to claim 1 wherein the at least one primary oil type fuel comprises at least one oil selected from the group consisting of mineral oils, kerosene oils, synthetic kerosene oils, naphtha oils, synthetic oils, bio oils, gasoline oils, diesel oils, synthetic diesel oils, line seed oils and neatsfoot oils.

6. A composition according to claim 1 wherein the first oil type fuel with flash point under 100? C. constitutes between 0.1 to 10% by weight of the composition.

7. A composition to claim 1, wherein the fuel phase further comprises at least one oil type fuel with a viscosity of at least 50 cP at 15? C. to increase the emulsion composition viscosity.

8. A composition according to claim 1, wherein the secondary oil type fuel is selected from the group of mineral oils, petroleum oils, aromatic oils, bio-oils, synthetic fuel oils, diesel oils, lubrication oils, kerosene oils, naphtha oils, paraffin oils, lubrication oils, chlorinated paraffin oils, micro benzene oils, toluene oil, polymeric oils, rapeseed oils, coconut oils, silicone oils and fish oils.

9. A composition according to claim 1, wherein the fuel-phase further comprises at least one wax selected from the group consisting of microcrystalline wax, paraffin wax, animal wax, plant wax, montan wax, polyethylene wax and polyethylene derivative wax.

10. A composition according to claim 1, further comprising a grease lubricant in the form of a solid or semifluid dispersion of a thickener in oil.

11. A composition according to claim 1, wherein the at least one emulsifier is selected from the group consisting of: Polyisobutylene succinic anhydride (PIBSA), PIBSA amine derivatives, Polyisobutenyl succinic acid anhydride (PIBDIBA), PIBDIBA derivates, PIB-lactone and its amino derivatives, Sorbitan monooleate (SMO), sorbitan sesquioleate, lecithin, alkoxylates, esters combinations, fatty amines, alkyloxazolines, alkenyloxazolines, imidazolines, alkyl-sulfonates, alkylarylsulfonates, alkylsulfosuccinates, alkylphosphates, alkenylphosphates, phosphate esters and mixtures thereof.

12. A composition according to claim 1 wherein the apparent viscosity of the composition is between 35 000 and 120 000 centipoise (cP).

13. A composition according to claim 2 wherein the density of the sensitized emulsion explosive is between 0.4-1.25 grams per cm.sup.3.

14. A composition according to claim 1, wherein the fuel phase comprises at least one oil having no more than 18 carbon atoms in the molecular structure, preferably 10 to 18 carbon atoms.

15. A method of preparing an emulsion type explosive composition, which method comprises: providing an oxidizer-phase comprising at least 35% by weight of hydrogen peroxide and at least 25% by weight of water, providing a fuel-phase comprising at least one primary oil type fuel with a flash point below 100? C. and at least one secondary oil type fuel with a flash point over 150? C., providing at least one emulsifier, forming an emulsion comprising the oxidizer-phase, the fuel-phase and the emulsifier, in which emulsion the oxidizer-phase is discontinuously dispersed throughout the continuous fuel-phase, and sensitizing the emulsion by adding gas filled compressible solid micro-balloons, and/or by generating gas bubbles by means of a gassing agent and/or by adding gas bubbles to the emulsion.

Description

DETAILED DESCRIPTION OF EXAMPLES

[0065] According to one aspect of the invention, there is provided a composition for forming a hydrogen peroxide based emulsion explosive as set out in appended claim 1. The composition comprise a oxidizer phase comprising at least 35% by weight of hydrogen peroxide and at least 25% by weight of water, a fuel phase comprising at least one oil type fuel with a flash point below 100? C., and an emulsifier, wherein the oxidizer-phase is discontinuously dispersed throughout the continuous fuel phase.

[0066] In practice, the composition may be formed by mixing the hydrogen peroxide water solution forming the oxidiser-phase with the fuel-phase in a mixer to thereby create an emulsion with the oxidiser phase being dispersed in the fuel phase. Preferably the emulsifier should be added to the fuel phase prior to mixing. Alternatively, the emulsifier may be added during the mixing process for forming the emulsion. Typically, the temperature of the oxidiser-phase may be kept at approx. 10-20? C. when added to the mixer. During preparation of the fuel-phase, which may comprise mixing the low flashpoint oil-based fuel with the, the temperature of the fuel-phase may be kept at room temperature. However, when oil fuels having lower viscosity are used it may be preferable to add heat during the formation of the fuel phase. Correspondingly, the fuel phase may be supplied to the emulsification mixer at room temperature or it may be somewhat pre-heated before being supplied to the mixer.

[0067] By adding a sensitizer, the composition becomes detonation enabled and explosive though initiation with conventional means such as a detonator with or without an amplification charge (known as a primer or booster).

[0068] The sensitizer bubbles may be chemically generated though a chemical reaction caused by a gassing agent added as a part of a pumping process whereby gas bubbles are formed slowly in-situ of the composition once placed in a blast hole. An example of gassing agents which may be used is carbon powder suspended in water. Another example is a mixture of vinegar (CH.sub.3COOH) and bicarbonate solved in water. When carbon powder suspended in water is used, the suspension will react with the hydrogen peroxide to form oxygen bubbles which act as hot spots in the composition. When vinegar and bicarbonate is used, these two substances react with each other to form hot carbon dioxide bubbles acting as hot spots.

[0069] In another embodiment, a sensitizer comprising enclosed gas bubbles in the form of hollow microspheres formed of e.g. glass, ceramic, plastic or cellulose are added mechanically and mixed into the composition making the composition sensitized and thereby detonation enabled immediately.

[0070] It will be appreciated that the composition of the invention can be used for many purposes, but in particular to break and move rock in mining operations.

[0071] According to different embodiments of the composition it many comprise the types of functional components listed in Table 1;

TABLE-US-00001 TABLE 1 Typical types of functional components and ratios exemplifying compositions Ratios in % by weight of the total Type of functional component composition HP (primary oxidizer) From 35 to 60 Water From 25 to 55 Primary oil fuels with flash From 0.1 to 10 point under 100? C. Secondary oil fuels with flash From 0 to 5 point over 150? C. Non-oil secondary fuels From 0 to 10 Secondary oxidizers From 0 to 30 Emulsifiers From 0.8 to 5 Additives From 0 to 5

[0072] Such compositions may have the properties listed in Table 2:

TABLE-US-00002 TABLE 2 Properties of the exemplifying compositions Properties Value Oxygen balance From ?10 to +5 Un-sensitized density From 0.8 to 1.8 Sensitized density From 0.4 to 1.25 Viscosity From 35 000 to 120 000 cP Velocity of detonation 2200-5500 m/s

[0073] Exemplifying typical substances for each type of functional component are listed in Table 3:

TABLE-US-00003 TABLE 3 Exemplifying substances comprised in the compositions Function Component Oxidizers(s) At least 35% Hydrogen peroxide by weight, optionally potassium peroxide/and, or sodium peroxide/ and, or perchlorate salts/and, or chlorate salts. Fuel(s) Mineral oils, petroleum oils, aromatic oils, bio- oils, synthetic fuel oils, diesel oils, lubrication oils, kerosene oils, naphtha oils, paraffin oils, lubrication oils, chlorinated paraffin oils, micro benzene oils, toluene oil, polymeric oils, rapeseed oils, coconut oils and fish oils, metal powders, sugars, glycerol or alcohols. Emulsifiers Emulsifiers containing lipophilic and hydrophilic moieties (Polyisobutylene succinic anhydride (PIBSA), PIBSA amine derivatives, PIB-lactone and its amino derivatives, Sorbitan monooleate (SMO), sorbitan sesquioleate, lecithin, alkoxylates, esters combinations, fatty amines, alkyloxazolines, alkenyloxazolines, imidazolines, alkyl-sulfonates, alkylarylsulfonates, alkylsulfosuccinates, alkylphosphates, alkenylphosphates, phosphate esters) able to bond the HP solution. Additives pH adjusters, thickeners, rheology modifiers, HP stabilizers (phosphonic acid or tin based compounds), lubricant greases Sensitizer Gas filled voids or bubbles either chemically generated (delayed or instant) and/or gas entrapped compressible materials.

EXAMPLES

[0074] The present invention can be used for a variety of forms of emulsion type explosive compositions provided of course that the principles of the invention as described herein are observed. The invention is further illustrated with reference to the following examples.

Example 1

[0075]

TABLE-US-00004 TABLE 4 Composition rations used in example 1 Ratio Component Function (weight %) Comment Hydrogen Oxidizer 92.6 50% HP peroxide Discontinuous solution (50%) phase Synthetic Fuel 2.7% Flash point over paraffin oil Continuous phase 200? C. Synthetic Fuel .sup.2% Flash point kerosene Continuous phase 70? C. PIBSA Emulsifier/Fuel 1.3% Continuous phase SMO Emulsifier/Surfactant 1.4% Continuous phase

[0076] A hydrogen peroxide explosive composition was prepared according to Table 4;

[0077] The continuous phase was prepared separately and heated to approximately 50? C. before adding the discontinuous oxidizer phase. Oxidizer phase was added slowly during high shear mixing ensuring emulsification. The formulation resulted in a thick emulsion with an apparent viscosity of approx. 85 000 cP and a pH level of 3.9. Cup density was measured to 1.15 g/cm.sup.3.

[0078] 1.2% of a chemical gassing agent comprising a carbon powder suspended in water with a thickener was added and the density changed to 0.86 g/cm.sup.3. The composition was sensitized within approx. 40 minutes and the composition was left to sleep for approx. 5 hours. Thereafter, 3 samples with 1 kg each of the sensitized emulsion was placed in a plastic sleeve with an inner diameter of 38 mm and initiated unconfined with an 8 d standard detonator. Velocity of detonation was done using the MREL microtrap system with a 1 meter copper probe. VOD values was where measured to be over 4000 meters per second.

Comparative Example 2

[0079] A hydrogen peroxide explosive composition was prepared similar to the one illustrated in Table 4, however without the low flash point component (Synthetic Kerosene). The composition is presented in Table 5 below;

TABLE-US-00005 TABLE 5 Composition ratios used in example 2. Ratio Component Function (weight %) Comment Hydrogen peroxide Oxidizer 92.6 50% HP (50%) Discontinuous solution phase Synthetic Fuel 4.7% Flash point over paraffin oil Continuous phase 200? C. PIBSA Emulsifier/Fuel 1.3% Continuous phase SMO Surfactant 1.4% Continuous phase

[0080] The continuous phase was prepared separately and heated to approximately 50? C. before adding the discontinuous oxidizer phase. Oxidizer phase was added slowly during high shear mixing ensuring emulsification. The formulation resulted in a thick emulsion with a higher apparent viscosity compared to example 1 of approx. 100 000 cP and a PH level of 4.1. Cup density was measured to 1.16 g/cm.sup.3.

[0081] 1.2% of a same chemical sensitizer as example 1 was added and the density changed to 0.89 g/cm.sup.3. The composition was left to sleep for approx. 5 hours and thereafter, 3 samples with 1 Kg each of the gassed emulsion was placed in a plastic sleeve with inner diameter of 38 mm and initiated unconfined with an 8 d standard detonator. Velocity of detonation was done using the MREL microtrap system with a 1-meter copper probe. None of the samples successfully detonated.

[0082] Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms within the scope of the appended claims. In particular features of any one of the various described examples may be provided in any combination in any of the other described examples.