INSERTION OF A BLASTING DEVICE This invention relates to a method and apparatus for inserting a blasting device into a substance to be blasted. It is particularly relevant to non- explosive blasting methods, such as those using a rapid gas-discharge to produce a blast. One known type of blasting device uses sudden vaporisation of carbon dioxide (CO2) to create a blast. This blasting device comprises an elongate metal tube, having a chamber for holding a charge of liquid carbon dioxide. A heater is provided inside the chamber, for vaporising the liquid, and there is a discharge head at the forward end of the tube, for releasing the vaporised carbon dioxide. When the device is triggered, the heater causes the carbon dioxide to vaporise almost instantaneously. The resulting increase in pressure inside the chamber causes a shear disc to rupture, releasing the gaseous carbon dioxide through the discharge head.

Pressures of up to 3000 bar can be realised using this method. The pressure (and therefore power) of the blast can be controlled by selecting a shear disc that is designed to rupture at a desired predetermined pressure. After use, the device can be recovered and reused by replacing the heater and rupture disc and refilling the chamber with liquid CO2. Since the blasting method is non-explosive and controllable, it is especially advantageous in certain applications where the use of explosives would be damaging or dangerous, or would result in contamination.

One such application is cleaning the interior of storage or production vessels used to hold granular materials such as powders. A problem of such vessels is that solid accretions of material can build up on their interior surfaces, reducing their effective capacity and/or resulting in blockages. A gas- discharge blast, as described above, can safely dislodge the accumulated "caked" powder without damaging the vessel. Furthermore, the gaseous CO2 will not contaminate the vessel or its contents.

Another application is the use of gas-discharge blasting in mining or quarrying. It is known, for example, to use a gas-discharge blast as described above in coal mining. Here, a significant advantage is that the carbon dioxide discharged is non-flammable - indeed it will act to extinguish fire.

A blasting device of the type described above is disclosed in WO 2012/095687 and sold by Cardox International Limited, a UK company.

Conventionally, in order to insert the blasting device into the material to be blasted, a bore is drilled into the material, by an operator. The operator then manually slides the blasting device into the pre-drilled bore.

According to an aspect of the present invention, there is provided an apparatus and method as defined in the independent clams.

In one aspect, the invention provides an apparatus for inserting a blasting device, comprising:

The blasting device; and

a percussion mole for inserting the blasting device into a substance to be blasted.

A percussion mole - also known variously as a percussive mole, impact borer, or soil displacement hammer - is conventionally used in trenchless digging, to allow pipes or cables to be laid underground while minimising disturbance at the surface. The present inventor has recognised that a percussion mole could advantageously be used to insert a blasting device into a material to be blasted. Compared with the conventional approach of drilling a bore and manually pushing the blasting device into it, this method has several potential advantages. The separate step of drilling can be eliminated, since the blasting device can be coupled to the mole and then inserted in a single step. Furthermore, the depth of penetration is no longer limited by the size of the drill, which may be useful in confined spaces, such as in underground shafts or storage silos. The blasting device may also be installed in the material more tightly and securely - the mole works by compressing and/or displacing the surrounding material as it forces its way forwards, thereby creating the bore for the blasting device in the process of insertion. This should provide a tighter fit than pre-drilling a bore of the same cross-section as the blasting device to be inserted. A tighter fit may enable the blasting device to function more effectively.

Furthermore, the method of the invention effectively provides a pre- made bore, and this prevents the problem of collapse of the bore before device insertion.

The mole is preferably adapted for coupling with the blasting device. Alternatively, in some embodiments the two parts could be fabricated as a single integral apparatus.

The blasting device is preferably a non-explosive blasting device, more preferably a gas-discharge blasting device.

The blasting device can comprise:

a chamber for holding a liquid charge;

a heater for vaporising the liquid; and

a discharge head for releasing the vaporised liquid.

The liquid is preferably carbon dioxide. The blasting device is preferably refillable with a further liquid charge and reusable.

Preferably, the percussion mole has a front end and a rear end, with first engagement means provided at the front end of the mole;

the blasting device has a front end and a rear end, with second engagement means provided at the rear end of the blasting device,

wherein the first engagement means and second engagement means are adapted to engage with one another for coupling the mole and the blasting device.

In this configuration, the mole is arranged to drive the blasting device ahead of it into the material to be blasted.

The mole and blasting device may be adapted to loosely engage one another, wherein there is substantially no resistance to disengagement. Alternatively, they may be adapted to tightly engage one another, wherein the coupling resists disengagement. The front end of the blasting device may be tapered, wherein the cross sectional area reduces towards the front. This may facilitate penetration into the material to be blasted.

The second engagement means can comprise a socket and the first engagement means comprises a head that is shaped to engage in the socket. The head can then have a stepped profile which decreases in cross section towards the front end of the mole.

For example, the head may comprise two longitudinally arranged concentric cylinders of different diameter with a step between them. The first cylinder, towards the front of the mole has the smaller diameter and may be adapted to fit inside the socket on the rear of the blasting device. The second cylinder has the larger diameter and may be adapted to engage against a rearward end-surface of the socket.

The percussion mole can be operable without a liquid lubricant.

For example, the moving parts of the mole may be coated or surface- treated to reduce friction, such that lubricant is unnecessary. Avoiding a liquid lubricant may be advantageous, since lubricant might contaminate the substance being blasted.

The percussion mole can be powered by a driving fluid, the apparatus further comprising an inflow pipe for delivering driving fluid to the mole and an exhaust pipe for returning spent driving fluid.

The driving fluid preferably comprises compressed air. That is, the mole is preferably a pneumatic mole. However, a hydraulic mole may also be used.

It may be advantageous to return the exhaust compressed air via an exhaust pipe (rather than discharging it around the mole, for example) so that any contaminants in the compressed air remain isolated from the substance to be blasted. This can help to avoid contamination of the substance. For example, compressed air may comprise traces of oil that is used to lubricate the air-compressor. This oil could contaminate substances such as foodstuffs.

According to another aspect of the invention, there is provided a method of inserting a blasting device in a substance to be blasted, the method comprising: coupling the blasting device to a percussion mole; and operating the percussion mole to drive the blasting device into the substance.

The method may further comprise activating the blasting device to blast the substance.

The blasting device can comprise:

a chamber for holding a liquid charge;

a heater for vaporising the liquid; and

a discharge head for releasing the vaporised liquid.

The step of coupling the blasting device to the percussion mole can comprise coupling the front of the percussion mole to the rear of the blasting device.

The method of inserting the blasting device may be used in an industrial process clearing method.

The substance to be blasted can be a caked granular material inside a storage or production vessel, or inside pipework. The vessel may be a silo. The granular material may be one of: clinker, cement; sand; grain; maize; soya; flour; sugar; gypsum; fertilizer; and/or may be any material in powder form.

The material may be adhered to the interior surface of the vessel and the method may comprise blasting the material to dislodge it.

The blasting device may be inserted from outside the vessel, through a port in the wall of the vessel, or may be inserted into the material from inside the vessel.

Also provided is a method of cleaning a production or storage vessel, or industrial pipework, comprising the inserting method of the invention.

The substance to be blasted may for example be embedded in the ground.

The blasting may be performed as part of a method of quarrying, mining, or excavating the material being blasted. The substance to be blasted then can comprise coal or rock. The rock may comprise a metal ore, for example. Further provided is a method of mining or quarrying material. The invention will now be described by way of example with reference to the accompanying drawing, in which:

Fig. 1 is a schematic diagram of an apparatus for inserting a blasting device according to an embodiment of the invention.

It should be noted that this figure is diagrammatic and not drawn to scale. Relative dimensions and proportions of parts have been shown exaggerated or reduced in size, for the sake of clarity and convenience. Fig. 1 shows an apparatus for inserting a blasting device, according to a first embodiment of the invention. The apparatus comprises the blasting device 10 and a percussion mole 100. The blasting device 10 is of the type described in WO 2012/095687 and its internal parts are not shown here, for clarity and simplicity. Externally, the blasting device 10 comprises a tapered nose 20 at its front end; a discharge head 30 behind the tapered nose 20; a main casing 40 behind the discharge head 30; and a firing head 50 at the rear of the main casing 40. The tapered nose 20 forms a pointed spike, to make it easier to drive the blasting device 10 into the substance to be blasted. The discharge head 30 has a plurality of holes 32 for rapidly discharging the gaseous CO2 when the blasting device 10 is fired. The main casing 40 houses the chamber containing the liquid carbon dioxide charge and the heater for vaporising the carbon dioxide (not shown in Fig. 1 ). The firing head 50 is connected internally to the heater and is used to control the firing of the blasting device 10. Ignition wires 60 enable the firing to be controlled remotely, electrically.

The percussion mole 100 used in this embodiment is similar to the one described in WO2012/007756. However, this mole is used by way of example only and other moles could also be used. The mole 100 is pneumatic and operates in a known way. For this reason - and for greater clarity - the internal working of the mole will not be described in greater detail herein and is not pictured in Fig. 1 . The mole 100 comprises a main body 1 10 with a cylindrical head 120 at its forward end. A compressed air pipe 130 is provided for delivering pressurised air to power the mole; and an exhaust pipe 140 is provided for the return of spent air.

The blasting device 10 and mole 100 are coupled together by means of a metal socket pipe 80. A screw-thread is provided on the exterior of the main casing 40 of the blasting device 10, at a rear portion of the main casing 40. A corresponding thread is provided on the inside surface of the socket pipe 80, at its front end. This enables the socket pipe 80 to be fixed to the rear of the main casing 40, by screwing the two parts together. The cylindrical head 120 at the front of the percussion mole 100 is shaped to engage in the rear end of the socket pipe 80. The main body 1 10 of the mole 100 is wider than the diameter of the cylindrical head 120, providing a stepped profile. When the cylindrical head 120 is engaged in the rear of the socket pipe 80, the step at the front of the main body 1 10 engages against the rear end-surface of the socket pipe 80. Together, the cylindrical head 120 and the stepped profile at the front of the main body 1 10 provide first engagement means for coupling the mole 100 to the blasting device 10. Likewise, the rear end of the socket pipe 80 forms second engagement means adapted to receive the first engagement means. Once coupled together, the forward driving force applied by the mole 100 will be transferred to the main casing 40 of the blasting device 10 via the socket pipe 80. This avoids any impact-forces being delivered to the firing head 50 at the rear of the blasting device 10.

An opening is provided in the socket pipe 80 for the ignition wires 60. The wires 60 are threaded through this opening, to connect to the firing head 50. Metal piping 70 is provided at the outside of the socket pipe 80 at the location of the opening. The ignition wires 60 run through this metal piping 70. This protects the wires 60 from damage while the blasting device 10 and mole 100 are being driven forwards into the substance to be blasted.

To use the apparatus, the percussion mole 100 is coupled to the rear of the blasting device 10 as described above. Compressed air is then supplied to the mole 100 to drive it forward pneumatically. The mole forces the blasting device 10 into the substance to be blasted, ahead of the mole. When the blasting device has been inserted into the material to the desired depth, the compressed air supply is switched off. The blasting device is then fired from a remote location, via the ignition wires 60. Afterwards, both the mole and the blasting device can be retrieved and reused.

The apparatus and method described above are useful in many applications. The combination of the percussion mole 100 with the blasting device 10 provides all the advantages of the blasting device 10 without the drawbacks associated with drilling a bore in the material to be blasted, before inserting the blasting device 10. The embodiment pictured in Fig. 1 may be particularly beneficial for cleaning and unblocking production and storage vessels, such as silos. The blasting device 10 has the advantage that the carbon dioxide released in the blast does not contaminate the vessel or the material being blasted inside the vessel. The mole 100 is also designed to avoid contamination. Unlike some conventional moles, the used compressed air is not vented around the mole but is instead returned via the exhaust pipe 140. This avoids contamination due to release of the air. In particular, it is common for compressed air to contain traces of oil that is used to lubricate the air compressor that supplies the compressed air. The present embodiment avoids any contamination due to this oil, by returning the exhaust air via the exhaust pipe 140, thereby keeping it isolated from the environment where the blasting is being performed. The far end of the exhaust pipe 140 can be located outside the vessel being cleaned, where the exhaust air can be safely vented to the atmosphere. As a result, the carbon dioxide discharged from the blasting device 10 is the only substance which is released inside the vessel being cleaned.

The exhaust gases discharged can also be processed using a separator or collector if desired, so as not to discharge muist contamination into the atmosphere at all.

Conventionally, the blasting device 10 would be inserted into the substance to be blasted through a port in the wall of the vessel to be cleaned. The apparatus of Fig. 1 can be used in the same way, with the further advantage that the percussion mole 100 may be used to embed the blasting device 10 more deeply inside the vessel. Alternatively, the apparatus of Fig. 1 may be inserted from the top of a storage silo. For example, the mole 100 can be used to insert the blasting device 10 in caked powder material by driving the blasting device 10 vertically downwards, parallel to a side wall of the silo. In theory, there is no limit to the depth to which the blasting device 10 can be inserted using this method. The depth of penetration is determined only by the length of the air pipes 130 and 140 and the ignition wires 60.

The apparatus of Fig. 1 can also be useful in other applications where the blasting device 10 is to be fully embedded in a material to be blasted. For example, the apparatus may be beneficial in blasting for coal mining.

While the invention has been illustrated and described in detail in the drawing and foregoing description, such illustration and description are to be considered exemplary and not restrictive. The invention is not limited to the described embodiments.

For example, it is possible to operate the invention in an embodiment wherein the blasting device 10 and percussion mole 100 are provided as an integrated unitary apparatus (rather than separate components to be coupled together, as described above).

When the blasting device 10 and mole 100 are provided as separate components, they may be coupled together by any suitable means. The socket pipe 80 described above is merely one beneficial example. Note also that the socket pipe 80 is not necessarily screwed to the end of the casing 40 of the blasting device 10. Instead, any other suitable means of fixing the socket pipe 80 to the casing 40 could be used. These include but are not limited to welding or bolting.

In the embodiment described above, the mole disclosed in

WO2012/007756 was used. However, as those skilled in the art will appreciate, other percussion moles could also be used. Nevertheless, as explained above, it may be beneficial to use a percussion mole having an exhaust pipe 140, since this may help to avoid contamination by the venting of air from the mole 100 into the void space around the mole.

Various other modifications will be apparent to those skilled in the art.