Apparatus and method for lining a blast hole

Abstract

An apparatus for lining a blast hole comprises a tube of thermoplastic material and a welder for welding the tube, wherein an end of the tube can be welded closed by the welder and the desired length of tube can be dispensed and cut free from the rest of the tube when the closed end is at least part way inside the blast hole. There is also a method of lining a blast hole which comprises welding closed an end of a tube of thermoplastic material; placing the closed end in the blast hole and allowing it to descend into the hole; dispensing a desired length of tube; and cutting free the length of tube from the rest of the tube.

Claims

1. An apparatus for lining a blast hole comprising a tube of thermoplastic material and a portable thermoplastic welder; wherein the tube is held in a dispenser, wherein the tube is in a substantially continuous cylindrical form prior to being dispensed from the dispenser, wherein the welder is configured to weld the tube transverse to a length of the tube, wherein when the welder is operated an end of the tube is welded closed transversely to the length of the tube by the welder, wherein a desired amount of the length of tube required for the blast hole at the site of the blast hole is able to be dispensed from the dispenser, wherein the dispensed substantially continuous cylindrical tube is able to be cut free from the rest of the tube when the closed end is at least part way inside the blast hole.

2. An apparatus for lining a blast hole according to claim 1, wherein the welder applies a heat to the tube in pulses by contact with the tube so as to weld the end of the tube closed.

3. An apparatus for lining a blast hole according to claim 1, wherein the apparatus is portable.

4. An apparatus for lining a blast hole according to claim 1, wherein the apparatus is mounted on a vehicle.

5. An apparatus for lining a blast hole according to claim 4, wherein the welder comprises a timer for turning off welding heat applied to the tube for welding closed the end after a set period of time.

6. An apparatus for lining a blast hole according to claim 5, wherein the welder is operable to weld closed of the end of the tube while in transit until the timer turns off the welding heat.

7. An apparatus for lining a blast hole according to claim 1, wherein the welder comprises a cutter for cutting a free end from the rest of the tube.

8. An apparatus for lining a blast hole according to claim 1, wherein when the tube is filled with explosive the weld holds the explosive inside of the tube, and the weld prevents ground water from entering the tube when the weld is in the blast hole.

9. A method of lining a blast hole comprising: providing a dispenser holding a tube of thermoplastic material which is in a substantially continuous cylindrical form prior to being dispensed from the dispenser; welding closed an end of the tube of thermoplastic material on-site, wherein the weld is transverse to a length of the tube; placing the closed end in the blast hole and allowing it to descend into the hole; dispensing a desired amount of the length of tube required for the blast hole from the dispenser; and cutting free the desired amount of the length of tube from the rest of the tube.

10. A method of lining a blast hole according to claim 9, wherein the method further comprises moving to another blast hole and repeating the method for the other blast hole.

11. A method of lining a blast hole according to claim 9, wherein the method further comprises welding closed a cut end of a surface remainder of the tube on-site for use in a next blast hole.

12. A method of lining a blast hole according to claim 11, wherein the welding closed of the end of the tube is conducted while in transit to the next blast hole.

13. A method of lining a blast hole according to claim 12, further comprising operating a timer for determining when to turn off welding heat applied to the tube for welding closed the end while in transit.

14. A method of lining a blast hole according to claim 9, wherein when the tube is filled with explosive the weld holds the explosive inside of the tube, and the weld prevents ground water from entering the tube when the weld is within the blast hole.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In order to provide a better understanding of the present invention embodiments will be described in further detail below with reference to the accompanying drawings, in which:

(2) FIG. 1 is a schematic set of diagrams of a prior art process of sealing a gusseted plastic tube for insertion into a blast hole;

(3) FIG. 2 is a perspective view of a welding apparatus for sealing an end of a gusseted plastic tube held in a spool;

(4) FIG. 3 shows a schematic set of diagrams showing a method of sealing the gusseted tube with the apparatus of FIG. 2 for insertion into a blast hole.

DETAILED DESCRIPTION

(5) The present invention provides an apparatus and method for lining blast holes with a liner tube formed of composite thermoplastic materials and having a welded closed end.

(6) Referring to FIG. 2, a welder 10 is shown having a lid 20 and a dispenser 26, which contains a roll of gusseted tube 28 (see also FIG. 3). The dispenser 26 can freely rotate in order for the gusseted tube 28 to be readily dispensed when pulled. The dispenser 26 is positioned on the welder 10 such that the dispensed portion of the gusseted tube 28 can be fed through the upper 12 and lower 14 clamping members (and hence welded, as described below). The dispenser 26 enables bulk tube dispensing and roll on loading in order to reduce manual handling. Typically the welder 10 will be mounted to a vehicle. Typically this will be on the side of a tray of a utility vehicle.

(7) Referring to FIG. 3, there is shown a roll 28 of the gusseted tube of composite thermoplastic tube. For clarity the welder 10 is not shown. The tube has an open end 32. The thermoplastic materials may be present in the composite thermoplastic materials in any suitable discrete form. In some embodiments, the composite thermoplastic materials may, for example, be discrete polymer layers of a laminate material. In some embodiments, the composite thermoplastic materials may be in the form of strands of discrete polymers which are, for example, woven into substantially planar sheets. For example, as will be discussed in further detail below, tubular sheets having a combination of PP and PE strands in the weave (typically the PP runs in the vertical direction or warp and PE runs in the horizontal direction or weft) have been found to have advantageous properties. In particular, the PP warp offers minimal stretch and excellent abrasion resistance as well as improved environmental factors, whereas the PE weft is present to bind everything together and provides a better hermetic seal. As would be appreciated, sheets made from woven materials would be more tear resistant than many other forms of construction.

(8) Such tubes may also have an internal (or external) laminate in order to provide additional advantageous properties (e.g. waterproofing or air resistance). In such cases, a laminate having a similar polymer to that present in the (woven) parent materials might help to improve the weld because the internal lamination is likely to bind better and, during welding, the heat transfer is improved and the heated plastic flows better, binding the parent materials and laminate together with greater mechanical strength. This means that the barrier created by the weld between the outside of the bag and the inside of the bag can be vastly superior to that provided by conventional welding techniques.

(9) Sufficient free tube is dispensed. In this example at least 700 mm (typically about 1 m) of free tube is dispensed. At a desired length the tube is sealed by welding with the welder 10. In order to weld the composite thermoplastic a new welding technique is used by the welder 10 which entails pulsed heating to form the weld 34. The weld 34 forms a moisture barrier.

(10) A weight 36 is inserted into the open end 33 of the tube 32. Typically the weight 36 is borehole cuttings (dirt). The free end is then folded over the weld 34 as indicated by 38. The folded end is about 300 mm from the weld 34 as shown.

(11) A cable tie 40 is then slipped over the folded end in the vicinity of the weld 34, but preferably about 50 mm above the weld 34 at 42 and tightened. The cable tie 40 maintains the weight inside the end portion of the tube and also prevents the initial load of explosives from rupturing the weld 34.

(12) The weight 36 is used to weigh the tube down to assist it in lowering into the borehole 50. The tube is then rolled off the dispenser 26 until the weight reached the bottom, or the desired depth.

(13) The length can be cut from the dispenser and filled with explosive with at least 700 mm of free end from the welder jaws. However generally this will occur sometime later. In one option the end can be welded sealed until it is needed to be filled with explosive, however this may not be necessary. The tube can be secured above the opening 50 to the blast hole with a spike or by use of a stand in the blast hole. The operator can then move on to the next bore hole to be lined. The operator may close the jaws on the material to weld closed the end so that by the time the operator arrives at the next hole the material 28 is sealed and ready to receive the weight, which saves time. When needed, the opening of the tube inside the blast hole can be filled with explosive so as to fill the blast hole, with the tube acting as a liner of the blast hole.

(14) It will be appreciated by those skilled in the art that variations and modifications to the embodiments of the invention described herein will be apparent without departing from the spirit and scope thereof. The variations and modifications as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth.