CA1312777C - Charging of explosives into boreholes - Google Patents
Charging of explosives into boreholesInfo
- Publication number
- CA1312777C CA1312777C CA000531148A CA531148A CA1312777C CA 1312777 C CA1312777 C CA 1312777C CA 000531148 A CA000531148 A CA 000531148A CA 531148 A CA531148 A CA 531148A CA 1312777 C CA1312777 C CA 1312777C
- Authority
- CA
- Canada
- Prior art keywords
- explosive
- pump
- borehole
- assembly
- sensitizing agent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42D—BLASTING
- F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
- F42D1/08—Tamping methods; Methods for loading boreholes with explosives; Apparatus therefor
- F42D1/10—Feeding explosives in granular or slurry form; Feeding explosives by pneumatic or hydraulic pressure
Landscapes
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
Abstract
ABSTRACT
"Charging of Explosives into Boreholes"
The invention provides a method of charging a pumpable explosive into a borehole, and to a borehole charging assembly for this purpose. The method involves pumping the pumpable explosive into the borehole and, while the explosive is being pumped into the borehole, mixing a sensitizing agent into the explosive to enable gas bubbles of size 70 to 200 microns in diameter to be formed in the explosive. The assembly comprises a container for a pumpable, unsensitized explosive, a second container for a sensitizing agent and a pump for pumping explosive. The assembly incluces a mixing device which is connected in series with the pump outlet.
"Charging of Explosives into Boreholes"
The invention provides a method of charging a pumpable explosive into a borehole, and to a borehole charging assembly for this purpose. The method involves pumping the pumpable explosive into the borehole and, while the explosive is being pumped into the borehole, mixing a sensitizing agent into the explosive to enable gas bubbles of size 70 to 200 microns in diameter to be formed in the explosive. The assembly comprises a container for a pumpable, unsensitized explosive, a second container for a sensitizing agent and a pump for pumping explosive. The assembly incluces a mixing device which is connected in series with the pump outlet.
Description
-2- ~3~2777 ~ECI ~67 T~IIS INVENTION relates to the charging of explosive into boreholes. ~lore particularly, ~he invention relates to a method of charging a pumpable explosive into a borehole, and to a borehole charging assen~ly for charging a pumpable explosive into a borehole.
According to one aspect of the invention there is provided a method of charging a pumpable explosive into a borehole, which method comprises pumping the pwnpable explosive into the borehole; and while the explosive is being pumped into the borehole, mixing a sensitizing agent illtO the explosive to enable gas bubbles of size 70 to 200 microns iTl di~meter to be ~ormed in tile explosive.
Pumping the explosive may be by means of any suitable pump.
Thus, the pwnping may be by means of an orbiting helical positive displacement screw pump, such as a Mono pump, the pumping taking place from a container containing unsensitized pumpable explosive mounted on mobile ~ransport means such as a lorry, rail truck, or like vehicle.
The sensitizing agent may also be pumpable, being eg a fluid material such as a chemical gassing solution. The mixing of the explosive and the sensitizing agen-t into the explosive may include passing the sensitizing agen~ together with the explosive through the pump which is used to pump the explosive down the borehole, so that the sensitizing agent and explosive are at least partially mixed in the 3 ~3~2777 ~un~ en the sensitizing agent is pwnpable, as melltiorlcd a~ove, the method ma~ include pumping the scnsitizing agent from a container into the pump which is used to pump the explosive down the borchole. This container, and the container used for the explosive, may be a tank, hopper, or the li~e.
The mixing may includé passing the explosivè delivered by the punlp which is used to pump the explosive down the borehole together with the sensitizing agent through a mixing device. The mixing device may be a static mixer. There may be one oI more such static mixers, and they will be typically provided, eg in series, downstream of the pwnp used to pump the explosive do~l the borehole, and the mixture will issue from said mixing device or devices as an explosive which is starting to become sensitized by gas bubbles of size 70 to Z00 microns in diameter, and which mixture passes directly from the mixing device or devices into the borehole.
The containers, pump or pumps and mixing device or mixing devices, all conveniently form part of an interco Mected borehole charging assembly as described hereunder, mown~ed together on mobile transport means.
The method may be used for charging boreholes undergrowld, in which case it may include the preliminary steps of formulating the explosi~e as a repumpable unsensitized formulation undergrownd, and then pumping this formulation into a hopper or tank on an undergrownd vehicle from which, in accordance with the invention, it is pumped into the borehole while being sensitized. Naturally, ~n similar situations above growld, the method may include the similar preliminary steps of 7 r~ r~
ormulatillg the unsellsitized explosive on site as a rcpumpable fo~ulatioll, alld then pumping it into a tank or hopper on a vehicle, from which it is pumped into a borehole.
~ccording to another aspect of the invention there is provided a borehole chargillg assembly, for chargillg a pun~able explosive into a borehole, which assembly comprises a container for pumpable unsensitized explosive, a container ~or sensitizing agent, a pump for pwnping the explosive, and a mixing device, the containers having outlets connected to the pump inlet and the mixing device being comlected in series with the pump to the pump outle~.
The pump may be an orbiting helical positive displacement pump. There may be a plurality of mixing devices comlected in series with the pwnp, downstream of ~he p~np, the mixing devices and pump being arranged such that the assembly is capable of pumping an explosive containing gas bubbles o size 7 to 200 microns in diameter.
~ ach container may be a fluid container, having its outlet colmected by a fluid flow line to the pump inlet.
The pump outlet m~y be connected directly to the inlet of the mixing device into which it feeds; and the flow line from the container for the sensitizing agent to the pump may include a further pun~ for pumping sensitizing agent from said contahler to the pump for pumping explosive. The assembly may include a flow meter, for metering flow of sensitizing agent from the container for the sensitizing agent to the pumps, the flow meter being provided eg in ~he flow line between said further pump and the container for the sensitizillg agent.
S ~ 7 rl 7 1ll a ~)articular embodilncnt of the invelltion tl~erc rnay be a sillgle mixin~ d~ice, and the mixing device may be a static mixer, eg a static mixer of the type comyrising a tubular housing one or typically several mixing elements arr,~n~ed in series in the housing. As mentioned above, the static mixer may be connected directly to the outlet of the pump for pun~ g the explosive.
The assembly may be mounted on mobile transport means. Thus, the assembly as a whole may be mounted on mobile transport means such as a lorry, rail truck, sled, or the like, and conveniently includes a power supply drivingly connected to each pump. In use, the out let of the pump for pumping the explosive may be be connected, via the mixing device, to a hose or the liké for insertion into a borellole to be charged.
The explosive may be an emulsion explosive in which an oxidizing salt-containing component forms the discontinuous phase, the continuous phase comprising a fuel component WhiC}I is immiscible Wit]
- the discontinuous phase. Such explosives, when the oxidizing salt-containing comyonent contains water and is in the form of an aqueous solution are known as 'water-in-fuel1 emulsions, and when the oxidizing salt-containing component contains little or no water can be regarded as 'melt-in-fuel' emulsions.
The discontinuous phase may comprise at least one oxidizing salt selected from the group consisting in :
~mmonium nitrate alkali metal nitrates alkaline earth metal nitrates 1312 ~ ~ 7 .m~loniwn perchlorate urea alkali metal perchlorates and al~aline earth metal perchlorates.
Whell the discontinuous phase comprises ammonium nitrate, it may comprise one or more further compounds such as sodium nitrate, calcium nitrate, urea or the like which, to~ether with the ammonium nitrate, form a melt which has a melting point which is lower than that of the ammonium nitrate, the further colnpounds being capable of reacting as oxygen releasing salts or fuels. The discontinuous phase may in certain cases comprise water, which is kept to a minimum to avoid wasted energy arising from steam generation, but which is employed to facilitate melting/dissolving of tile oxidizing salt component to avoid excessively high processing temperatures during formation of the base emulsion. When selecting the proportion of water used in the emulsion to which the sensitizing solution is added, the proportion of any water in such sensitizing solution as is used can be bom~ in mind, to determine the proportion of water which will be present in the final explosive product.
The fuel of the fuel component of ~he emulsion may form from 2-25~ by mass of the emulsion, preferably about 3-12%.
The fuel of the fuel component of the emulsion will be immiscible with and insoluble in water, and may be non-self-explosive, comprising eg at least one member of the group consisting in hydrocarbons, halogenated hydrocarbons and nitrated hydrocarbons. Thus the uel may comprise at least one member of the group consisting in 7- ~3~2777 r,~ eral oils, fuel oils, lubricating oils, li~uid paraffin, microcl~stalline waxes, paraffin waxes, xylene, toluene, petrolatum, slack wax and dinitrotoluene.
When the emulsion is intended to be repun~able, any constituents thereof such as microcrystalline waxes, parafIill waxes, petrolat~nn, slack waxes, or the like whic}l, if used in excess, can affect its repun~ability, will be used in sufficiently small proportions so that they do not adversely affect this repumpability.
The fuel component of the emulsion may comprise at least one emulsifier s~lected from the group consistillg in sorbitan sesquioleate, sorbitan monooleate, sorbit~l monopalmitate, sodium monostearate, sodium tristearate, the mono- and diglycerides of fat-forming fa~ty acids, soya bean lecithin, derivatives of lanolin, alkyl benzene sulphonates, oleyl acid phosphate, laulylamine acetate, decaglycerol decaoleate, decaglycerol decastearate, 2~oleyl-4,4'-bis(hydroxymethyl)-2-oxazoline, polymeric emulsifiers containing polyethylene glycol backbones with fatty acid side chains and polyisobutylene succinic anhydride derivatives.
The emulsifiers act as surfactants and stabilizers ~o promote the formation of the emulsion and to resist crystallization and/or coalescense of the discontinuous phase.
The method may include dispersing a density reducing agent therein to reduce the density of the emulsion to within the desired range of 1,0-1,5 g/cm3 mentioned above.
This t~e of explosive, witllout the density reducing agent, ie the sensitizing agent referred to above, will be contained in one of the tal~ks or hoppers, and the sensitizing agent, which will function as a density reducillg agent, will be contained in the other tank or hopper.
5Typical emulsions or use in accordance with the method of the present invention will comply with the following broad fonmulation:
FO~LA~ION
Constituent FunctionTypical proportion in formulation on a mass basis (m/m) ~nonium nitrate Oxidizing salt60,0 - 75,0 Sodium nitrate Oxidizing salt0,0 - 20,0 Calcium nitrate Oxidizing salt0,0 - 20,0 15 Water Solvent 9,0 - Z2,0 Sorbitan monooleate Emulsifier 0l5 - 4,0 Fuel oil Fuel 1,0 - 5,0 Acetic acid Buffer 0,0 - 1,0 Thiourea Catalyst 0,1 - 1,0 Sodium acetate - Stabilizer 071 - 1~0 The thiourea acts to catalyse the reaction between the ammonium nitrate and sodium nitrite described hereunder, and the acetic acid buffers the pH of the oxidizing salt component to a desirable value.
For this particular type of explosive, the ammonium nitrate and sodium nitrate components may be partially replaced by perchlorates of the type mentioned above, calcium nitrate, or the like. Mineral oil such as P9S Mineral oil available from BP South Africa (Proprietary) Limited m.ly be substituted for the fuel oil, alld other hlown emulsifiers o~ the type recited above may be substituted for the sorbitan monooleate. Other catalysts such as thiocyanate can be substituted or the thiourea, and other buffers such as citric acid for the acetic acid.
Furthermore, if desired, finely divided solid fuels such as aluminiun~ or ferrosilicon can be added to the emulsioll.
For emulsions of the type set out in the above table, any suitable sensitizing agent may be used~ but the invention contemplates yarticularly employing a pumyable sensitizing solution in the form of an aqueous solutioll of sodium nitrite. In this gassing solution the sodium nitrite will typically make up 10-40~ by mass, the water, correspondingly, making up 6~-~0% by mass.
To the emulsions of the type set out in the table above, typically 0,5-3,0 parts by mass of this gassing solution will be added.
In accordance with the method, thus, the pump will be used to withdraw the emulsion from the emulsion hopper, and the gassing solution from its tank, the flow lines from said hopper and tank entering the inlet or throat of the pump, and the flow being assisted by gravity and the drop in pressure below ambient pressure at the pump inlet caused by operation of the pump. Initial mixing of sensitizing solution and emulsion will take place in the pump itself, and final mixing to acceptable homogeneity in the mixing device downstream of the pump. The sodium nitrite in the gassing solution will react with ammonium nitrate in the emulsion to produce nitrogen (N2) bubbles, which act to reduce the density of the emulsion, thereby to sensitize it. In this regard it should be noted that the mixing device, eg the static mixer, should be -lo~ 131~7 ~ ~
seleeted so that bubbLes are produced having ~ average siLe of between and 2~ microns, w;th all the bubbles produced preferably being ~ithin tlliS r~lge ~nd evenly and homogeneously dispersed throughout the emulsion. The explosive, in its sensitized form, will flow immediately from the mixing device into the borehole, so that time spent handling a sensitized e~plosive, with the associated danger, is kept to a minimum.
The invention will now be described, by way of illustrative non-lLmiting example, with reference to the accompanying diagrammatic drawings and worked example.
In the drawings, FIGURE 1 shows a schematic side elevation of a borehole charging assenlbly in accordance with the present invention, in its operative condition in use in accordance with the me~hod of the present invention, for above ground use; and FIGU~E 2 shows a similar view of another assembly according to the invention for underground use.
In Figure 1 of the drawings, reference numeral 10 generally designates a borehole charging assembly in accordance with the present invention. The assembly is mounted on a lorry generally designated by referellce numeral 12.
The assembly 10 con~rises a ~iono pump 14 mounted by brackets 16 Oll the load bed 18 of the lorry. The Mono pump has a drive shaft 20, connected by drive transmission means (not shown) to a power supply (also not shown) both mo~l~ed on the load bed 18.
3~777 The p~np l~ has an inlet in the fo~m of a flanged pipe 22 co~ected b~ a shut-off valve 24 having an operating handle 26, to a flanged pipe 28 constituting the outlet of an emulsion hopper 30. A
chemic~l gassing solution tank 32 is mounted alongside the hopper 30, and has an outlet provided by a pipe 3~ which is connected via a shut-off valve 36 having an operating handle 38, to a hose 40 which feeds through a flow meter 41 and a further pump into a branch pipe 42 of the pipe 22, leading into the pipe 22. The br~lch pipe 42 has a non-return valve 43 which prevents flow from the pipe 22 to the hoMer 32. This furtller pump, designated 44, is a small centrifugal pump such as a Jabsco pwnp. Although shown suspended from the hose ~0 in the drawings, the Jabsco pump will in ~act be mounted on the load bed 18 of the lorry 12.
The pump 14 has an outlet at 45 provided with a flange 46 via which it is colmected to the flange 48 of the inlet 50 of a static mixer 52. The outlet at 54 of the static mixer is connected to an explosive loading hose 56 sllown inserted into a borehole 58 in rock 60 to be broken, and wherein other boreholes are also designated 58.
, Suitable support means, such as legs, struts or the like (not shown) are provided, whereby the hopper 30 and tank 32 are mounted on the load bed 18 of the lorry 12.
In use, the hopper 30 and the tank 32 will respectively be charged with emulsion and gassing solution from suitable sources of supply. The lorry 12 will then be driven to the rock face 62, which may be above ground or underground in a mine, wherein the boreholes 58 have been drilled. The lorry 12 will be stopped in a convenient position, -12- 13~27~7 alld the hose 5h, whicll is conveniently pennanently attached to the outlet 54 Or the mixer 52, ~Id carried in a coiled state on the load bed 18, will then be uncoiled and inserted into the appropriate borehole 58.
The pwnps 1~ and 44 will then be driven by their power supplies (not sho~n), which may be mowlted Oll the load bed 18 of the lorry 12, simultaneous operation of the ~wnps 14 and 44 automatically withdrawing) after opening of the valves Z4 9 36 J emulsion from the hopper 30 and gassing solution from the tank 32.
Mixing of gassing solution and emulsion will start in the pump 1~, and will progress in the mixer 52 to adequate homogeneity, nitrogen bubbles simultaneously starting to be fonmed in the emulsion, in the size range 70-200 microlls and homogeneously dispersed in the emulsion.
These gas bubbles are eg nitrogen bubbles formed by reaction of sodium nitrite in the gassing solu~ion with ammonium nitrate in the emulsion, for the fonnulation set out in the Example hereunder. This chemical gassing and density reduction, eg to a density of 1,0-1,5 g/cm2, sensitizes the emulsion to detonation by me~ls of a blasting cap or the like.
The sensitized emulsion is pumped directly from the assembly 10 via the hose 56 into the borehole 58, after which it can be detonated when desired.
The bubbles will continue to form in the mixer 52, in the hose 56 and in the borehole 58. Bubble formation will be complete several minutes after the explosive has been charged into the borehole 58.
-13~ 27~7 Figure 2 of the drawings shows a substantially similar assembly to that of Figure 1, except that the lorry 12 is replaced by an underground vehicle 64. ~nless otherwise specified the same reference numerals refer to the same parts. For both Figures 1 and 2 it is contemplated that the emulsion will be formulated on site (above ground or underground as the case may be) as a repumpable emulsion and then pumped into the hopper 30 to be taken by the vehicle 12, 64 to the boreholes 58.
The assembly described above with reference to Figure 2 of the drawings has been successfully tested with the explosive and sensitizing agent formulations set out in the following Example:
EXAMPLE
A water-in-oil or water-in-fuel emulsion having the foll~wing composition was used:
Con tituent Proportion in parts m/m Ammonium nitrate 64 Sodium nitTate 12 Water 17,3 Sorbitan monooleate 1,0 Fuel oil . 5,0 Acetic acid 0,1 Thiourea o,5 Sodium acetate O,1 As a gassing solution a solution of sodium nitrite was used, comprising one part by mass of sodium nitrite dissolved in five parts by mass of water.
3~277 ~
In accor~ ce with the method described above, with reference to the drawings, and using the assembly shown in the drawing, the sensitizirlg solution was used to sensitize the base or unsensitized emulsion, while pumping the emulsion into boreholes. It should be noted that 98,8 parts of base ernulsion were mixed with 1,2 parts by mass of sensitizing solution.
The method and assembly were found to provide a conveniently employed inexpensive and rela~ively safe method and means for charging boreholes. In particular, the invention has the advantage that the base emulsion is transported in its relatively safe unsensiti%ed state and is partially sensitized for an extremely short period belore charging thereof into the boreholes, being indeed fully sensitized only several minutes after it has been charged into the boreholes.
According to one aspect of the invention there is provided a method of charging a pumpable explosive into a borehole, which method comprises pumping the pwnpable explosive into the borehole; and while the explosive is being pumped into the borehole, mixing a sensitizing agent illtO the explosive to enable gas bubbles of size 70 to 200 microns iTl di~meter to be ~ormed in tile explosive.
Pumping the explosive may be by means of any suitable pump.
Thus, the pwnping may be by means of an orbiting helical positive displacement screw pump, such as a Mono pump, the pumping taking place from a container containing unsensitized pumpable explosive mounted on mobile ~ransport means such as a lorry, rail truck, or like vehicle.
The sensitizing agent may also be pumpable, being eg a fluid material such as a chemical gassing solution. The mixing of the explosive and the sensitizing agen-t into the explosive may include passing the sensitizing agen~ together with the explosive through the pump which is used to pump the explosive down the borehole, so that the sensitizing agent and explosive are at least partially mixed in the 3 ~3~2777 ~un~ en the sensitizing agent is pwnpable, as melltiorlcd a~ove, the method ma~ include pumping the scnsitizing agent from a container into the pump which is used to pump the explosive down the borchole. This container, and the container used for the explosive, may be a tank, hopper, or the li~e.
The mixing may includé passing the explosivè delivered by the punlp which is used to pump the explosive down the borehole together with the sensitizing agent through a mixing device. The mixing device may be a static mixer. There may be one oI more such static mixers, and they will be typically provided, eg in series, downstream of the pwnp used to pump the explosive do~l the borehole, and the mixture will issue from said mixing device or devices as an explosive which is starting to become sensitized by gas bubbles of size 70 to Z00 microns in diameter, and which mixture passes directly from the mixing device or devices into the borehole.
The containers, pump or pumps and mixing device or mixing devices, all conveniently form part of an interco Mected borehole charging assembly as described hereunder, mown~ed together on mobile transport means.
The method may be used for charging boreholes undergrowld, in which case it may include the preliminary steps of formulating the explosi~e as a repumpable unsensitized formulation undergrownd, and then pumping this formulation into a hopper or tank on an undergrownd vehicle from which, in accordance with the invention, it is pumped into the borehole while being sensitized. Naturally, ~n similar situations above growld, the method may include the similar preliminary steps of 7 r~ r~
ormulatillg the unsellsitized explosive on site as a rcpumpable fo~ulatioll, alld then pumping it into a tank or hopper on a vehicle, from which it is pumped into a borehole.
~ccording to another aspect of the invention there is provided a borehole chargillg assembly, for chargillg a pun~able explosive into a borehole, which assembly comprises a container for pumpable unsensitized explosive, a container ~or sensitizing agent, a pump for pwnping the explosive, and a mixing device, the containers having outlets connected to the pump inlet and the mixing device being comlected in series with the pump to the pump outle~.
The pump may be an orbiting helical positive displacement pump. There may be a plurality of mixing devices comlected in series with the pwnp, downstream of ~he p~np, the mixing devices and pump being arranged such that the assembly is capable of pumping an explosive containing gas bubbles o size 7 to 200 microns in diameter.
~ ach container may be a fluid container, having its outlet colmected by a fluid flow line to the pump inlet.
The pump outlet m~y be connected directly to the inlet of the mixing device into which it feeds; and the flow line from the container for the sensitizing agent to the pump may include a further pun~ for pumping sensitizing agent from said contahler to the pump for pumping explosive. The assembly may include a flow meter, for metering flow of sensitizing agent from the container for the sensitizing agent to the pumps, the flow meter being provided eg in ~he flow line between said further pump and the container for the sensitizillg agent.
S ~ 7 rl 7 1ll a ~)articular embodilncnt of the invelltion tl~erc rnay be a sillgle mixin~ d~ice, and the mixing device may be a static mixer, eg a static mixer of the type comyrising a tubular housing one or typically several mixing elements arr,~n~ed in series in the housing. As mentioned above, the static mixer may be connected directly to the outlet of the pump for pun~ g the explosive.
The assembly may be mounted on mobile transport means. Thus, the assembly as a whole may be mounted on mobile transport means such as a lorry, rail truck, sled, or the like, and conveniently includes a power supply drivingly connected to each pump. In use, the out let of the pump for pumping the explosive may be be connected, via the mixing device, to a hose or the liké for insertion into a borellole to be charged.
The explosive may be an emulsion explosive in which an oxidizing salt-containing component forms the discontinuous phase, the continuous phase comprising a fuel component WhiC}I is immiscible Wit]
- the discontinuous phase. Such explosives, when the oxidizing salt-containing comyonent contains water and is in the form of an aqueous solution are known as 'water-in-fuel1 emulsions, and when the oxidizing salt-containing component contains little or no water can be regarded as 'melt-in-fuel' emulsions.
The discontinuous phase may comprise at least one oxidizing salt selected from the group consisting in :
~mmonium nitrate alkali metal nitrates alkaline earth metal nitrates 1312 ~ ~ 7 .m~loniwn perchlorate urea alkali metal perchlorates and al~aline earth metal perchlorates.
Whell the discontinuous phase comprises ammonium nitrate, it may comprise one or more further compounds such as sodium nitrate, calcium nitrate, urea or the like which, to~ether with the ammonium nitrate, form a melt which has a melting point which is lower than that of the ammonium nitrate, the further colnpounds being capable of reacting as oxygen releasing salts or fuels. The discontinuous phase may in certain cases comprise water, which is kept to a minimum to avoid wasted energy arising from steam generation, but which is employed to facilitate melting/dissolving of tile oxidizing salt component to avoid excessively high processing temperatures during formation of the base emulsion. When selecting the proportion of water used in the emulsion to which the sensitizing solution is added, the proportion of any water in such sensitizing solution as is used can be bom~ in mind, to determine the proportion of water which will be present in the final explosive product.
The fuel of the fuel component of ~he emulsion may form from 2-25~ by mass of the emulsion, preferably about 3-12%.
The fuel of the fuel component of the emulsion will be immiscible with and insoluble in water, and may be non-self-explosive, comprising eg at least one member of the group consisting in hydrocarbons, halogenated hydrocarbons and nitrated hydrocarbons. Thus the uel may comprise at least one member of the group consisting in 7- ~3~2777 r,~ eral oils, fuel oils, lubricating oils, li~uid paraffin, microcl~stalline waxes, paraffin waxes, xylene, toluene, petrolatum, slack wax and dinitrotoluene.
When the emulsion is intended to be repun~able, any constituents thereof such as microcrystalline waxes, parafIill waxes, petrolat~nn, slack waxes, or the like whic}l, if used in excess, can affect its repun~ability, will be used in sufficiently small proportions so that they do not adversely affect this repumpability.
The fuel component of the emulsion may comprise at least one emulsifier s~lected from the group consistillg in sorbitan sesquioleate, sorbitan monooleate, sorbit~l monopalmitate, sodium monostearate, sodium tristearate, the mono- and diglycerides of fat-forming fa~ty acids, soya bean lecithin, derivatives of lanolin, alkyl benzene sulphonates, oleyl acid phosphate, laulylamine acetate, decaglycerol decaoleate, decaglycerol decastearate, 2~oleyl-4,4'-bis(hydroxymethyl)-2-oxazoline, polymeric emulsifiers containing polyethylene glycol backbones with fatty acid side chains and polyisobutylene succinic anhydride derivatives.
The emulsifiers act as surfactants and stabilizers ~o promote the formation of the emulsion and to resist crystallization and/or coalescense of the discontinuous phase.
The method may include dispersing a density reducing agent therein to reduce the density of the emulsion to within the desired range of 1,0-1,5 g/cm3 mentioned above.
This t~e of explosive, witllout the density reducing agent, ie the sensitizing agent referred to above, will be contained in one of the tal~ks or hoppers, and the sensitizing agent, which will function as a density reducillg agent, will be contained in the other tank or hopper.
5Typical emulsions or use in accordance with the method of the present invention will comply with the following broad fonmulation:
FO~LA~ION
Constituent FunctionTypical proportion in formulation on a mass basis (m/m) ~nonium nitrate Oxidizing salt60,0 - 75,0 Sodium nitrate Oxidizing salt0,0 - 20,0 Calcium nitrate Oxidizing salt0,0 - 20,0 15 Water Solvent 9,0 - Z2,0 Sorbitan monooleate Emulsifier 0l5 - 4,0 Fuel oil Fuel 1,0 - 5,0 Acetic acid Buffer 0,0 - 1,0 Thiourea Catalyst 0,1 - 1,0 Sodium acetate - Stabilizer 071 - 1~0 The thiourea acts to catalyse the reaction between the ammonium nitrate and sodium nitrite described hereunder, and the acetic acid buffers the pH of the oxidizing salt component to a desirable value.
For this particular type of explosive, the ammonium nitrate and sodium nitrate components may be partially replaced by perchlorates of the type mentioned above, calcium nitrate, or the like. Mineral oil such as P9S Mineral oil available from BP South Africa (Proprietary) Limited m.ly be substituted for the fuel oil, alld other hlown emulsifiers o~ the type recited above may be substituted for the sorbitan monooleate. Other catalysts such as thiocyanate can be substituted or the thiourea, and other buffers such as citric acid for the acetic acid.
Furthermore, if desired, finely divided solid fuels such as aluminiun~ or ferrosilicon can be added to the emulsioll.
For emulsions of the type set out in the above table, any suitable sensitizing agent may be used~ but the invention contemplates yarticularly employing a pumyable sensitizing solution in the form of an aqueous solutioll of sodium nitrite. In this gassing solution the sodium nitrite will typically make up 10-40~ by mass, the water, correspondingly, making up 6~-~0% by mass.
To the emulsions of the type set out in the table above, typically 0,5-3,0 parts by mass of this gassing solution will be added.
In accordance with the method, thus, the pump will be used to withdraw the emulsion from the emulsion hopper, and the gassing solution from its tank, the flow lines from said hopper and tank entering the inlet or throat of the pump, and the flow being assisted by gravity and the drop in pressure below ambient pressure at the pump inlet caused by operation of the pump. Initial mixing of sensitizing solution and emulsion will take place in the pump itself, and final mixing to acceptable homogeneity in the mixing device downstream of the pump. The sodium nitrite in the gassing solution will react with ammonium nitrate in the emulsion to produce nitrogen (N2) bubbles, which act to reduce the density of the emulsion, thereby to sensitize it. In this regard it should be noted that the mixing device, eg the static mixer, should be -lo~ 131~7 ~ ~
seleeted so that bubbLes are produced having ~ average siLe of between and 2~ microns, w;th all the bubbles produced preferably being ~ithin tlliS r~lge ~nd evenly and homogeneously dispersed throughout the emulsion. The explosive, in its sensitized form, will flow immediately from the mixing device into the borehole, so that time spent handling a sensitized e~plosive, with the associated danger, is kept to a minimum.
The invention will now be described, by way of illustrative non-lLmiting example, with reference to the accompanying diagrammatic drawings and worked example.
In the drawings, FIGURE 1 shows a schematic side elevation of a borehole charging assenlbly in accordance with the present invention, in its operative condition in use in accordance with the me~hod of the present invention, for above ground use; and FIGU~E 2 shows a similar view of another assembly according to the invention for underground use.
In Figure 1 of the drawings, reference numeral 10 generally designates a borehole charging assembly in accordance with the present invention. The assembly is mounted on a lorry generally designated by referellce numeral 12.
The assembly 10 con~rises a ~iono pump 14 mounted by brackets 16 Oll the load bed 18 of the lorry. The Mono pump has a drive shaft 20, connected by drive transmission means (not shown) to a power supply (also not shown) both mo~l~ed on the load bed 18.
3~777 The p~np l~ has an inlet in the fo~m of a flanged pipe 22 co~ected b~ a shut-off valve 24 having an operating handle 26, to a flanged pipe 28 constituting the outlet of an emulsion hopper 30. A
chemic~l gassing solution tank 32 is mounted alongside the hopper 30, and has an outlet provided by a pipe 3~ which is connected via a shut-off valve 36 having an operating handle 38, to a hose 40 which feeds through a flow meter 41 and a further pump into a branch pipe 42 of the pipe 22, leading into the pipe 22. The br~lch pipe 42 has a non-return valve 43 which prevents flow from the pipe 22 to the hoMer 32. This furtller pump, designated 44, is a small centrifugal pump such as a Jabsco pwnp. Although shown suspended from the hose ~0 in the drawings, the Jabsco pump will in ~act be mounted on the load bed 18 of the lorry 12.
The pump 14 has an outlet at 45 provided with a flange 46 via which it is colmected to the flange 48 of the inlet 50 of a static mixer 52. The outlet at 54 of the static mixer is connected to an explosive loading hose 56 sllown inserted into a borehole 58 in rock 60 to be broken, and wherein other boreholes are also designated 58.
, Suitable support means, such as legs, struts or the like (not shown) are provided, whereby the hopper 30 and tank 32 are mounted on the load bed 18 of the lorry 12.
In use, the hopper 30 and the tank 32 will respectively be charged with emulsion and gassing solution from suitable sources of supply. The lorry 12 will then be driven to the rock face 62, which may be above ground or underground in a mine, wherein the boreholes 58 have been drilled. The lorry 12 will be stopped in a convenient position, -12- 13~27~7 alld the hose 5h, whicll is conveniently pennanently attached to the outlet 54 Or the mixer 52, ~Id carried in a coiled state on the load bed 18, will then be uncoiled and inserted into the appropriate borehole 58.
The pwnps 1~ and 44 will then be driven by their power supplies (not sho~n), which may be mowlted Oll the load bed 18 of the lorry 12, simultaneous operation of the ~wnps 14 and 44 automatically withdrawing) after opening of the valves Z4 9 36 J emulsion from the hopper 30 and gassing solution from the tank 32.
Mixing of gassing solution and emulsion will start in the pump 1~, and will progress in the mixer 52 to adequate homogeneity, nitrogen bubbles simultaneously starting to be fonmed in the emulsion, in the size range 70-200 microlls and homogeneously dispersed in the emulsion.
These gas bubbles are eg nitrogen bubbles formed by reaction of sodium nitrite in the gassing solu~ion with ammonium nitrate in the emulsion, for the fonnulation set out in the Example hereunder. This chemical gassing and density reduction, eg to a density of 1,0-1,5 g/cm2, sensitizes the emulsion to detonation by me~ls of a blasting cap or the like.
The sensitized emulsion is pumped directly from the assembly 10 via the hose 56 into the borehole 58, after which it can be detonated when desired.
The bubbles will continue to form in the mixer 52, in the hose 56 and in the borehole 58. Bubble formation will be complete several minutes after the explosive has been charged into the borehole 58.
-13~ 27~7 Figure 2 of the drawings shows a substantially similar assembly to that of Figure 1, except that the lorry 12 is replaced by an underground vehicle 64. ~nless otherwise specified the same reference numerals refer to the same parts. For both Figures 1 and 2 it is contemplated that the emulsion will be formulated on site (above ground or underground as the case may be) as a repumpable emulsion and then pumped into the hopper 30 to be taken by the vehicle 12, 64 to the boreholes 58.
The assembly described above with reference to Figure 2 of the drawings has been successfully tested with the explosive and sensitizing agent formulations set out in the following Example:
EXAMPLE
A water-in-oil or water-in-fuel emulsion having the foll~wing composition was used:
Con tituent Proportion in parts m/m Ammonium nitrate 64 Sodium nitTate 12 Water 17,3 Sorbitan monooleate 1,0 Fuel oil . 5,0 Acetic acid 0,1 Thiourea o,5 Sodium acetate O,1 As a gassing solution a solution of sodium nitrite was used, comprising one part by mass of sodium nitrite dissolved in five parts by mass of water.
3~277 ~
In accor~ ce with the method described above, with reference to the drawings, and using the assembly shown in the drawing, the sensitizirlg solution was used to sensitize the base or unsensitized emulsion, while pumping the emulsion into boreholes. It should be noted that 98,8 parts of base ernulsion were mixed with 1,2 parts by mass of sensitizing solution.
The method and assembly were found to provide a conveniently employed inexpensive and rela~ively safe method and means for charging boreholes. In particular, the invention has the advantage that the base emulsion is transported in its relatively safe unsensiti%ed state and is partially sensitized for an extremely short period belore charging thereof into the boreholes, being indeed fully sensitized only several minutes after it has been charged into the boreholes.
Claims (13)
1. A method of charging a pumpable explosive into a borehole, which method comprises pumping the pumpable explosive into the borehole; and while the explosive is being pumped into the borehole, mixing a sensitizing agent into the explosive to enable gas bubbles of size 70 to 220 microns in diameter to be formed in the explosive.
2. A method as claimed in Claim 1, in which the pumping is by means of an orbiting helical positive displacement screw pump and takes place from a container containing unsensitized pumpable explosive mounted on mobile transport means.
3. A method as claimed in Claim 1 in which the mixing of the sensitizing agent into the explosive includes passing the sensitizing agent together with the explosive through the pump which is used to pump the explosive down the borehole.
4. A method as claimed in Claim 3, in which the sensitizing agent is pumpable, the method including pumping the sensitizing agent from a container into the pump which is used to pump the explosive down the borehole.
5. A method as claimed in Claim 1, in which the mixing includes passing the explosive delivered by the pump which is used to pump the explosive down the borehole together with the sensitizing agent through a mixing device.
6. A method as claimed in Claim 5, in which the mixing device is a static mixer.
7. A borehole charging assembly, for charging a pumpable explosive into a borehole, which assembly comprises a container for a pumpable unsensitized explosive, a container for sensitizing agent, a pump for pumping explosive, and a mixing device, the containers having outlets connected to the pump inlet, and the mixing device being connected, in series with the pump, to the pump outlet.
8. An assembly as claimed in Claim 7, in which the pump is an orbiting helical positive displacement screw pump.
9. An assembly as claim in Claim 7 in which each container is a fluid container and has its outlet connected by a fluid flow line to the pump inlet.
10. An assembly as claimed in Claim 9, in which the flow line from the container for the sensitizing agent to the pump includes a further pump for pumping sensitizing agent from said container to the pump for pumping explosive.
11. An assembly as claimed in any one of Claims 7 to 9 inclusive, in which the mixing device is a static mixer.
12. An assembly as claimed in Claim 11, in which the static mixer is connected directly to the outlet of the pump for pumping explosive.
13. An assembly as claimed in any one of Claims 7 to 9 inclusive, in which the assembly is mounted on mobile transport means.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA861647 | 1986-03-05 | ||
| ZA86/1647 | 1986-03-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1312777C true CA1312777C (en) | 1993-01-19 |
Family
ID=25578311
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000531148A Expired - Fee Related CA1312777C (en) | 1986-03-05 | 1987-03-04 | Charging of explosives into boreholes |
Country Status (7)
| Country | Link |
|---|---|
| AU (1) | AU594423B2 (en) |
| BR (1) | BR8700949A (en) |
| CA (1) | CA1312777C (en) |
| GB (1) | GB2187490B (en) |
| MW (1) | MW587A1 (en) |
| NZ (1) | NZ219213A (en) |
| ZW (1) | ZW1487A1 (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| MW1689A1 (en) * | 1988-04-21 | 1989-12-13 | Aeci Ltd | Loading of boreholes with exploves |
| ZW9790A1 (en) * | 1989-06-14 | 1991-02-27 | Aeci Ltd | Permitted emulsion loading |
| SE505963C2 (en) * | 1993-02-25 | 1997-10-27 | Nitro Nobel Ab | Method for loading boreholes with explosives |
| AU726716B2 (en) * | 1996-10-18 | 2000-11-16 | Orica Explosives Technology Pty Ltd | Method of controlled blasting |
| AUPO307196A0 (en) * | 1996-10-18 | 1996-11-14 | Ici Australia Operations Proprietary Limited | Method of controlled blasting |
| DE10105590B4 (en) * | 2001-02-06 | 2005-04-28 | Westspreng Gmbh Sprengstoffe & | Method and apparatus for filling a cavity with mash explosive |
| NO315902B1 (en) * | 2001-12-27 | 2003-11-10 | Dyno Nobel Asa | Process for producing a sensitized emulsion explosive |
| CN111649636A (en) * | 2020-05-15 | 2020-09-11 | 包头市资达爆破设计施工有限责任公司 | Mixed loading vehicle explosive loading system and mixed loading vehicle |
| PE20231329A1 (en) | 2020-11-10 | 2023-08-28 | Dyno Nobel Asia Pacific Pty Ltd | SYSTEMS AND METHODS TO DETERMINE WATER DEPTH AND EXPLOSIVE DEPTH IN WELLS |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE787505A (en) * | 1971-08-16 | 1973-02-12 | Ici Australia Ltd | METHOD AND APPARATUS FOR FLOWING EXPLOSIVES |
| BE793571A (en) * | 1971-12-30 | 1973-04-16 | Nitro Nobel Ab | PRODEDE AND APPARATUS FOR LOADING EXPLOSIVES IN DRILL HOLES |
| BE793687A (en) * | 1972-01-18 | 1973-07-04 | Canadian Ind | MINE HOLES LOADING DEVICE |
| CA948904A (en) * | 1972-05-03 | 1974-06-11 | Canadian Industries Limited | Borehole loading and apparatus therefor |
| AU5461273A (en) * | 1972-05-03 | 1974-10-17 | Ici Australia Ltd | Loading a borehole |
-
1987
- 1987-01-09 GB GB8700482A patent/GB2187490B/en not_active Expired
- 1987-01-26 ZW ZW14/87A patent/ZW1487A1/en unknown
- 1987-01-30 MW MW5/87A patent/MW587A1/en unknown
- 1987-01-30 AU AU68176/87A patent/AU594423B2/en not_active Ceased
- 1987-02-09 NZ NZ219213A patent/NZ219213A/en unknown
- 1987-02-26 BR BR8700949A patent/BR8700949A/en not_active IP Right Cessation
- 1987-03-04 CA CA000531148A patent/CA1312777C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| MW587A1 (en) | 1987-10-14 |
| ZW1487A1 (en) | 1988-08-31 |
| NZ219213A (en) | 1988-09-29 |
| GB2187490A (en) | 1987-09-09 |
| GB2187490B (en) | 1989-12-06 |
| GB8700482D0 (en) | 1987-02-11 |
| AU594423B2 (en) | 1990-03-08 |
| BR8700949A (en) | 1987-12-29 |
| AU6817687A (en) | 1987-09-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6165297A (en) | Process and apparatus for the manufacture of emulsion explosive compositions | |
| AU2019223954C1 (en) | Inhibited emulsions for use in blasting in reactive ground or under high temperature conditions | |
| CA1312777C (en) | Charging of explosives into boreholes | |
| EP0207101A1 (en) | Gas bubble-sensitized explosive compositons | |
| US4207125A (en) | Pre-mix for explosive composition and method | |
| EP0330637A1 (en) | Blasting composition | |
| JP2942265B2 (en) | Emulsion explosive containing phenolic emulsifier derivative | |
| BR0201895B1 (en) | method of reducing the energy of an emulsion explosive agent and a reduced energy emulsion explosive agent. | |
| CA2469783C (en) | A method for preparing a sensitised emulsion explosive | |
| EP0460952A2 (en) | Emulsion that is compatible with reactive sulfide/pyrite ores | |
| CA2173566A1 (en) | Explosives | |
| WO1989002881A1 (en) | Methods and compositions related to emulsified gassing agents for sensitizing explosive compositions | |
| US4566919A (en) | Sensitized cast emulsion explosive composition | |
| US5084117A (en) | Explosive | |
| US4084993A (en) | Stable blasting slurry | |
| US6855219B2 (en) | Method of gassing emulsion explosives and explosives produced thereby | |
| CA2301552C (en) | Explosives gasser composition and method | |
| MXPA01011820A (en) | Blasting method for reducing nitrogen oxide fumes. | |
| AU753828B2 (en) | Explosives gasser composition and method | |
| AU725246B2 (en) | Process & apparatus for the manufacture of emulsion explosive compositions | |
| CN116806303A (en) | Hose end mixing system and method | |
| MXPA00000096A (en) | Process and mechanism for in situ sensitization of aqueous explosives |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |