WO2011057320A1

WO2011057320A1 - A method and apparatus for charging fluent material into tubes

Info

Publication number: WO2011057320A1
Application number: PCT/AU2009/001480
Authority: WO
Inventors: Richard John Johnson
Original assignee: Johnson Hi-Tech (Australia) Pty Ltd
Priority date: 2009-11-13
Filing date: 2009-11-13
Publication date: 2011-05-19

Abstract

A method and apparatus for charging fluent powder or granular explosives composition into semi-rigid polyethylene tubes (24) to produce explosives packages. The method includes locating the tubes (24) in a substantially vertical orientation at a charging station, feeding the composition into the tubes (24), and vibrating the tubes (24) independently of each other to promote uniform packing of the explosives composition therein. The apparatus includes a tube filler assembly (10) which comprises substantially vertically oriented, hollow support cylinders (30) for receiving tubes (24) designated for charging with an explosives material; a plurality of vibrators (34), one per support cylinder (30), for vibrating each tube (24), thereby to promote uniformity of packing of the explosives composition within the tube (24); and a tube filling guide in each of the support cylinders (30), located above the tube (24) for guiding the explosives composition into the tube (24).

Description

A METHOD AND APPARATUS FOR CHARGING FLUENT

MATERIAL INTO TUBES

FIELD OF THE INVENTION

This invention relates generally to the production of explosives packages containing explosives compositions, and in particular to a method and apparatus for charging fluent explosives material into tubes.

BACKGROUND OF THE INVENTION

It is well known to package explosives compositions used in mining applications in purpose designed containers to produce explosives "packages" which can readily be transported and handled. The explosives composition comprises dry powder or granulated compounds, emulsions, slurries, water gels, or the like, and the packages may be adapted to suit charge mass, borehole diameter, borehole length, and the like.

Australian Patent Application 1987081802 describes the packaging, in non-porous plastic cartridges of from 25mm to 75mm in diameter and 1000mm length, of an explosives composition comprising ammonium nitrate, paraffinic oil and foamed or expanded polystyrene beads.

British Patent 882665 describes the packaging of ammonium nitrate compositions in paper wrapped cartridges.

British Patent 1281421 also describes packaging of an ammonium nitrate explosive in a thin flexible plastic sheath such as polyethylene.

A known method for filling powder explosive comprises injection by means of pressurized air through nozzles from the top of a tube. The explosive is thereby blown into casings placed in a magazine. To attain good packing of the explosive inside the casings, a relatively high injection pressure is required. After each filling, the injection air is reduced to atmospheric pressure. This may pollute the working environment.

It is believed that discontinuity in the mass of explosives composition within a tube may give rise to a condition known as "gapping" where propagation of explosive energy along the charge column is interrupted. It is therefore desirable to promote well-compacted and uniform distribution of explosives composition throughout the tube.

A difficulty with flexible, thin walled elongate explosive charges is that when rolled into conveniently sized coils for packaging, transportation and storage, the tubular sheath is prone to kinking or flattening in parts. This can also occur when trying to insert elongate thin walled flexible tubular explosive charges into inclined or horizontal boreholes. At the position of the kink or flattened region, a discontinuity may be formed in the mass of explosives material. To alleviate the kinking problem the prior art proposed the use of shorter packages adapted for end-to-end coupling to form a long unitary charge. Thus there is still a demand not only for explosive packages containing well-dispersed and sufficiently compacted explosives compositions, but also packages of different lengths to suit different requirements and environments.

WO 92/03342 describes a filling machine for filling bags with products, including powder products. This machine uses a single stage vertical bottom-fill auger configuration which provides vibrational de- aeration directly within the auger bowl. An agitator moves and depresses the product during vibration of the auger bowl.

WO 92/08463 concerns a method for automated filling and packing of a powder or fluid in long tubes, and a packing and filling system for performing the procedure. Powder is poured via a distributor into tubes in a rotatable magazine which is engageable with a vibrator to promote compaction of the powder within the tubes.

SUMMARY OF THE INVENTION

It is an aim of the present invention to provide an effective method and means for filling tubes with a fluent explosives material to produce a relatively uniformly packed explosives package. Another aim of the invention is to provide a method and means for effectively filling tubes of different lengths with a fluent explosives material. According to the invention there is provided a method for charging a fluent explosives material into tubes located in a substantially vertical orientation at a charging station, which method comprises feeding the fluent material into the tubes while vibrating the tubes independently of each other, to promote uniform packing of the fluent material therein.

According to another aspect of the invention there is provided a method of manufacturing explosives packages, said method comprising the steps of:

providing a tube filler assembly having elongate, hollow support cylinders in which tubes designated for charging with a fluent explosives material are receivable in a substantially vertical orientation;

placing tubes designated for charging with explosives material, in the support cylinders;

charging said tubes with the explosives material; and

vibrating the tubes independently of each other, to promote uniform packing of the explosives material therein.

The method may include using a filling guide in each of the cylinders above an open mouth of the tube, and adjusting the distance between the filling guide and the tube mouth so as to guide the explosives material into the tube.

Preferably, vibrating of the tubes is carried out individually by separate vibrators, i.e. one vibrator per tube. Suitably, the method achieves a packing density of explosives material within the tubes, of greater than 1 gm cm^"3.

The method may include rotating the support cylinders about a vertical axis, thereby to move the tubes through an automated process which may include bringing each tube in turn into communication with a supply of the explosives material.

According to a further aspect of the invention there is provided a tube filler assembly for charging tubes with a fluent explosives material, which assembly includes:

substantially vertically oriented, hollow support cylinders for receiving tubes designated for charging with the explosives material;

a plurality of vibrators, one per support cylinder, and located with respect to the support cylinders such that, in use, the tubes can be vibrated independently of each other, thereby to promote uniformity of packing of the explosives material within the tube; and

a tube filling guide in each of the support cylinders which, in use, is located above the tube, for guiding the fluent explosives material into the tube.

The tube filler assembly may include a carousel on which the support cylinders are mounted and thereby are rotatable about a vertical axis so that, in use, each tube in turn can be brought into communication with a supply of the explosives material.

It will be appreciated that the support cylinders can accommodate tubes of different lengths and diameters. The predetermined amount of the explosives material will depend on the capacity, and hence the length and diameter, of each designated tube.

Each of the tube support cylinders may have an access opening adjacent an operative lower end thereof through which one of the tubes designated for charging with the explosives material, can be fed into the support cylinder. In a preferred embodiment, each of the tube support cylinders is in two sections which are spaced apart to provide the access opening for the tube.

The tube filler assembly may include a distributor located between a supply of the fluent explosives material and the support cylinders, the distributor comprising one or more calibrated supply units through which a predetermined amount of fluent explosives material can be charged into each of the tubes.

According to yet another aspect of the invention there is provided a tube filling guide for use with a support cylinder in which a tube designated for charging with a fluent explosives material can be accommodated, which filling guide is receivable in the support cylinder and displaceable along it, and comprises a funnel for guiding the explosives material into an open upper end of the tube.

The tube filling guide is particularly useful for tubes which are shorter than the respective support cylinders in which they are located. Each of the tube filling guides can be displaced within the cylinder to an optimal position for guiding the fluent explosives material into the tube.

The tube filling guide may include a shuttle for displacing the funnel along the cylinder. The shuttle may further serve to locate and support an upper region of the tube in the support cylinder while the tube is being charged with the explosives material.

The shuttle may carry a permanent magnet on an outer wall thereof, and then the funnel may be displaceable along the support cylinder by moving another magnet along an outer wall of the cylinder.

The support cylinders are preferably between about 5 metres and about 6 metres in length, and the carousel may be operated pneumatically, hydraulically or electrically, to effect displacement of the cylinders about a vertical axis.

The tubes may be formed from any suitable chemical resistant, semi-rigid plastics material such as polyvinyl chloride, polyethylene, polypropylene or the like, with a wall thickness of about 1mm. If required for use in horizontal or upwardly inclined boreholes, a ribbed tube may be selected from a stiffness range to permit easy insertion of the resulting packaged explosive into such boreholes. Suitably, said ribbed tube, in use, permits formation of the packed tube into a coil having an inner diameter of 200mm or greater without kinking.

Suitably, said plastics tube has a wall thickness in the range of from 300pm to 1500pm. Most preferably the tube has a wall thickness of 800pm to 1200pm. The tube may be sealed at opposite ends by any suitable means.

Suitably, the tube has an external diameter in the range 10mm to 50mm. Preferably, the tube has an external diameter of from 18mm to 25mm.

The present invention is not limited to any particular explosive composition and may comprise any conventional fluent explosives material or composition.

BRIEF DESCRIPTION OF THE DRAWINGS

The method and tube filler assembly of the invention are now described by way of the following non-limiting example, and with reference to the drawings in which:

Figure 1 is a schematic side view of a tube charging station which incorporates a tube filler assembly according to the invention;

Figure 2 is a schematic plan view of the tube charging station of

Figure 1 ;

Figure 3 is a schematic side view of the tube filler assembly;

Figure 4 is a three-dimensional view of a lower region of the tube filler assembly of Figure 3;

Figure 5 is a schematic diagram of a tube filling guide according to the invention, within a tube support cylinder of the assembly of Figure 3; and

Figure 6 is a flowchart for manufacturing explosives packages according to a method of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to the production of explosives packages containing explosives compositions and, in particular, provides a tube filler assembly for charging tubes with a fluent explosives material. The tube filler assembly includes substantially vertically oriented, hollow support cylinders for receiving tubes designated for charging with the explosives material. The assembly further includes a plurality of vibrators, one per support cylinder, which are located with respect to the support cylinders such that, in use, the tubes can be vibrated independently of each other, thereby to promote uniformity of packing of the explosives material within the tube. A tube filling guide is provided in each of the support cylinders and, in use, is located above the tube, for guiding the fluent explosives material into the tube. The invention extends to a method for charging a fluent explosives material into tubes located in a substantially vertical orientation at a charging station, by feeding the fluent material into the tubes while vibrating the tubes independently of each other, to promote uniform packing of the fluent material therein. The invention also extends to a method of manufacturing explosives packages as illustrated in Figure 1.

Embodiments of the present invention promote the effective and efficient production of uniformly packed explosives packages with a desired packing density, and provide the wherewithal to readily produce explosives packages of different lengths, using a single tube filler assembly having support cylinders of uniform length.

An embodiment of the present invention is now described, and elements thereof are illustrated in concise outline form in the drawings, showing only those specific details that are necessary for understanding the embodiment, but so as not to clutter the disclosure with excessive detail that will be obvious to those of ordinary skill in the art in light of the present description.

In this patent specification, references to "top" and "bottom", "upper" and "lower", "above" and "underneath", etc., are used solely to distinguish one element or method step from another element or method step without necessarily requiring a specific relative position or sequence that is suggested thereby. Further, words such as "comprises" or "includes" are not used to define an exclusive set of elements or method steps. Rather, such words merely define a minimum set of elements or method steps included in a particular embodiment of the present invention.

Figure 1 is a schematic side view of a tube charging station 8 which incorporates a tube filler assembly 10 according to the invention erected on a floor 12 of the station 8. The tube filler assembly is about 6 metres in height, and those regions of the tube filler assembly 10 requiring regular attention by an operator, are accessible via stairways 14 and intermediate platforms 16. At the charging station 8, a supply of a fluent, powder or granular explosives composition is transportable, via a conveyor 18, from a hopper 20 to a calibrated supply unit 22 above the tube filler assembly 10.

Figure 2 is a plan view of the tube charging station 8. The assembly 10 is designed to support tubes 24 in a substantially vertical orientation on a carousel (not shown in Figure 2), while they are charged with the explosives composition via the supply unit 22.

Figure 3 is a schematic side view of the tube filler assembly 10. The tubes 24 typically vary in length from 2 to 5 metres, and are of a semi-rigid plastics material having a diameter of about 20mm. They are destined for use in boreholes of 30-50mm in diameter. The tube filler assembly 10 includes a turntable 26 which supports a carousel 28 on which spaced apart, substantially vertically oriented, tube support cylinders 30 of stainless steel are mounted. Each of the cylinders 30 can accommodate one of the tubes 24.

Figure 4 is a three-dimensional view of a lower region of the tube filler assembly 10, showing the carousel 28 which has a base 32 about 1 metre above the floor 12. Each of the tube support cylinders 30 is about 50mm in diameter, and is in two sections 30.1 and 30.2. A lower, shorter section 30.1 is about 100mm in length and extends up from the carousel base 32, and an upper longer section 30.2 is about 4 metres in length and is aligned with, and spaced from, the lower section 30.1 to provide a gap of about 400mm in height between the two sections 30.1 , 30.2.

The tube filler assembly 10 includes electromechanical vibrators 34, one per tube support cylinder 30, for vibrating the tubes 24 so as to promote uniform packing, and desirable density, of the explosives composition therein. The vibrators 34 are located underneath the short sections 30.1 of the tube support cylinders which are designed to accommodate the sealed lower end portions of the tubes 24 while the tubes 24 are being charged.

Figure 5 is a schematic diagram of a tube filling guide 36 according to the invention, within one of the tube support cylinders 30. The long section 30.2 of each of the support cylinders 30 is provided with such a filling guide 36. The filling guide 36 comprises a funnel 38, and a shuttle 40 integral with the funnel 38 and displaceable within the cylinder 30. The shuttle 40 is cylindrical and defines a central, longitudinally extending passage 42 through which the explosives composition can pass into an upper end 44 of the tube 24 when the tube 24 is supported in the cylinder 30. The filling guide 36 has an inverted conical opening at its lower end 36.1 , and a conical opening at its upper end 36.2 which defines an upper catchment portion 46 of the funnel 38. The conical, catchment portion 46 of the funnel 38 has a maximum diameter slightly less than the internal diameter of the support cylinder 30. The funnel 38 also has a narrower tubular nozzle portion 48 which extends into the shuttle passage 42, and which is of a suitable length and diameter to be received into the upper end 44 of a tube 24 designated to be charged with explosives material, when the tube 24 is located in the support cylinder 30.

The shuttle 40 has a permanent magnet in the form of a magnetic strip 50 fixed to an outer wall 52 thereof. Another permanent magnet in the form of a magnetic block 54 is slidably attached to an outer wall 56 of the long section 30.2 of the support cylinder. The shuttle 40 can be located at a selected position within the support cylinder 30 by moving the magnetic block 54 along the outer wall 56 of the cylinder 30, thereby to displace the shuttle 40 within.

The method includes displacing the filling guide 36 along the support cylinder 30 to locate the funnel 38 in an optimal position for guiding the explosives material into the tube 24. The optimal position is attained when the funnel nozzle 48 extends a sufficient distance into the tube 24 to funnel the flow of explosives material therein, and inhibit spillage.

An example of the method of the invention is illustrated by way of a flowchart in Figure 6 in which a first step 62 includes providing tube filler assembly 10; a second step includes placing tubes 24 into support cylinders 30; a third step 66 includes locating filling guides 36 in each support cylinder 30 above the tube 24; a fourth step 68 includes rotating the support cylinders 30 about a vertical axis to bring each tube in turn into communication with a supply of the explosives material; a fifth step 70 includes charging a tube 24 with explosives material; and a sixth step 72 includes vibrating the tubes 24 independently of each other.

It will be appreciated that steps 62 to 72 are not necessarily carried out strictly consecutively. For example, the filling guides 36 can be appropriately located in the support cylinders 30 (step 66) prior to placing the tubes 24 therein (step 64). Furthermore, because the tubes 24 are charged, in turn, with the explosives material, vibrating of a first tube 24 (step 72) can be effected during and/or after charging of said first tube 24 with the explosives material (step 70), and can be continued while a second tube 24 is being rotated into communication with a supply of the explosives material (step 68) and/or being charged with the explosives material (step 70) and/or being vibrated (step 72).

The method of the invention is now described in more detail with reference to Figures 1-5.

At the tube charging station 8, the support cylinders 30 of the tube filler assembly 10 are loaded, as described below with reference to Figure 3, with tubes 24 which are open at their respective upper ends 44, and which have been sealed at their respective lower ends, for example with a rubber, plastics or timber bung (not shown).

Semi-rigid, high density polyethylene tubes 24 with a wall thickness of 1.0mm are preferred. The plastics material may include a conductive filler material such as carbon black to reduce a static electricity charge build up on the surface of the tube during handling. Conveniently, the tubes 24 may be similar to that currently employed as flexible electrical conduit by electricians.

The tubes 24 are inserted into the support cylinders 30, one per cylinder 30, as shown in Figure 3. This is achieved by pushing the open ends of the tubes 24 into the long sections 30.2 of the cylinders, and then guiding the sealed lower ends of the tubes 24 back into the short lower cylindrical sections 30.1.

When the polyethylene tubes 24 are loaded into the cylinders 30, the filling guides 36 are located at a predetermined optimal position in respective upper portions of the long cylindrical sections 30.2, by moving the magnetic block 54 along the outer walls 56 thereof (see Figure 5). As mentioned above, the optimal position is attained when the funnel nozzle portion 48 extends a sufficient distance into the tube 24 to funnel the flow of explosives composition into the tube 24 while inhibiting spillage, and where they assist in supporting the upper portion of the tube 24 in the cylinder 30.2.

The support cylinders 30 containing the tubes 24, are rotated on the carousel 28 (shown in Figures 3 and 4) about a vertical axis at appropriate time intervals to bring the tubes 24, in turn, into register with a nozzle 58 from the calibrated supply unit 22 located between the tube filler assembly 10 and the hopper 20 which contains a supply of the particulate explosives composition. An example of such a composition comprises 80- 85% ammonium nitrate (finely ground), 3-5% of a particulate carbonaceous fuel such as a coal dust, and 5-15% of a sensitizer such as aluminium powder, perchlorate, PETN, etc. A predetermined amount of the explosives composition is charged into each tube 24 in turn while the tube 24 is being vibrated by its dedicated electromechanical vibrator 34. The predetermined amount is calculated according to the length and internal diameter of the tube 24 and the desired density of the explosives composition therein, and is measured through the calibrated supply unit 22. Vibrating each tube 24 via its own dedicated vibrator 34, independently of the other tubes 24, promotes relatively even distribution of the explosives composition within the tube 24, effectively achieves the desired uniformity of packing and packing density, and minimises filling time.

When the tube 24 has been filled as required, any suitable plastics or cork bung or closure may be employed to seal the upper end 44 of the tube 24. When the upper ends 44 of the filled tubes 24 have been sealed and the tubes 24 have been vibrated sufficiently to achieve the desired packing characteristics, the tubes 24 are removed from the tube filler assembly 10 by lifting their lower ends out of the short cylindrical sections 30.1 (as shown in Figure 3), bending the tubes 24 slightly and pulling them down from within the upper cylindrical sections 30.2.

Other tubes 30 designated for filling are then loaded into the tube filler assembly 10, and the method of the invention is repeated.

Advantages of the method and tube filler assembly according to the invention, include the effective and efficient production of uniformly packed explosives packages with a desired packing density, and the wherewithal to readily produce explosives packages of different lengths, using a single tube filler assembly having support cylinders of uniform length.

The above description of an embodiment of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. Numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while a particular embodiment has been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. Accordingly, this patent specification is intended to embrace all alternatives, modifications and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above- described invention.

Claims

CLAIMS:

1. A method for charging a fluent explosives material into tubes located in a substantially vertical orientation at a charging station, which method comprises feeding the fluent material into the tubes while vibrating the tubes independently of each other, to promote uniform packing of the fluent material therein.

2. A method according to claim 1 , which includes supporting the tubes in hollow support cylinders, using a filling guide in each of the cylinders above an open mouth of the tube, and adjusting the distance between the filling guide and the tube mouth so as to guide the fluent explosives material into the tube.

3. A method of manufacturing explosives packages, said method comprising the steps of:

providing a tube filler assembly having elongate, hollow support cylinders in which tubes designated for charging with a fluent explosives material are receivable in a substantially vertical orientation,

charging said tubes with the explosives material; and

4. A method according to claim 3, which includes using a filling guide in each of the cylinders above an open mouth of the tube, and adjusting the distance between the filling guide and the tube mouth so as to guide the explosives material into the tube.

5. A method according to claim 3 which includes rotating the support cylinders about a vertical axis, thereby to bring each tube in turn into communication with a supply of the explosives material.

6. A tube filler assembly for charging tubes with a fluent explosives material, which assembly includes

7. A tube filler assembly according to claim 6, which includes a carousel on which the support cylinders are mounted and thereby are rotatable about a vertical axis so that, in use, each tube in turn can be brought into communication with a supply of the explosives material.

8. A tube filler assembly according to claim 6, which includes vibrators, one per support cylinder for vibrating, in use, the tubes designated for charging with the explosives material, so as to promote uniform packing, and desirable density, of the explosives material in the tubes.

9. A tube filler assembly according to claim 6, wherein each of the tube support cylinders has an access opening adjacent an operative lower end thereof through which one of the tubes designated for charging with the explosives material, can be fed into the support cylinder.

10. A tube filler assembly according to claim 9, wherein each of the tube support cylinders is in two sections which are spaced apart to provide the access opening for the tube. 1. A tube filler assembly according to claim 6, which includes a distributor located between a supply of the fluent explosives material and the support cylinders, the distributor comprising one or more calibrated supply units through which a predetermined amount of fluent explosives material can be charged into each of the tubes.

12. A tube filling guide for use with a support cylinder in which a tube designated for charging with a fluent explosives material can be accommodated, which filling guide is receivable in the support cylinder, and comprises a funnel for guiding the explosives material into an open upper end of the tube.

13. A tube filling guide according to claim 12, which includes a shuttle for displacing the funnel along the cylinder, and the shuttle has an outer wall which carries a permanent magnet, and is displaceable along the support cylinder by moving another magnet along an outer wall of the cylinder.