Field of the Invention

[0001] The present invention relates to a lubricated blast hole liner, including but not limited to a liner for use in deviated blast holes.

BACKGROUND OF THE INVENTION

[0002] In surface mining operations blasting is generally carried out by drilling a pattern of holes into a geological formation. The holes are filled with explosive, typically in liquid or gel form, which is detonated to break up rock of the formation.

[0003] When cracks are present in the geological formation, explosives pumped down the holes can leak into the cracks, affecting blasting. The cracks may be formed due to previous blasts nearby or may be formed naturally. Further it is common for water to enter the blast hole and water can adversely affect blast performance. When such cracks are encountered, or in a hole prone to entry of water, blasters commonly line the holes using a plastic liner that is supplied in roll form.

[0004] Problems arise when using this technique particularly when the holes, to be filled with explosive, are drilled and deviate from vertical. Another problem arises where sections of the lining may not fully open to receive the desired amount of explosive.

[0005] It is desired to provide an alternative or improved blast hole liner.

[0006] In this specification the terms “comprising” or “comprises” are used inclusively and not exclusively or exhaustively.

[0007] Furthermore, throughout the specification and the claims that follow, unless the context requires otherwise, the word “include” or variations such as “includes” or “including”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[0008] The words used in the specification are words of description rather than limitation, and it is to be understood that various changes may be made without departing from the spirit and scope of any aspect of the invention. Those skilled in the art will readily appreciate that a wide variety of modifications, alterations, and combinations can be made with respect to the above described embodiments without departing from the spirit and scope of any aspect of the invention, and that such modifications, alterations, and combinations are to be viewed as falling within the ambit of the inventive concept.

[0009] Any references to documents that are made in this specification are not intended to be an admission that the information contained in those documents form part of the common general knowledge known to a person skilled in the field of the invention, unless explicitly stated as such.

Summary of the Invention

[0010] According an aspect of the invention, there is provided a blast hole liner, comprising a length of flexible tubing comprising an internal surface coated with a lubricant.

[0011] In an embodiment of the invention, the lubricant comprises a hydrocarbon. In an embodiment of the invention, the lubricant comprises a liquid.

[0012] In an embodiment of the invention, the lubricant comprises an oil or a grease.

[0013] In an embodiment of the invention, the lubricant comprises a vegetable oil.

[0014] In an embodiment of the invention, the lubricant is non-reactive with a filling material.

[0015] In an embodiment of the invention, the blast hole liner is non-permeable.

[0016] In an embodiment, the blast hole liner comprises opposed gussets.

[0017] In an embodiment of the invention, the lubricant coats folded surfaces of one or more of the gussets.

[0018] In an embodiment of the invention, the blast hole liner comprises a woven material. In an embodiment blast hole liner comprises a layer so as to be non-permeable. [0019] In an embodiment of the invention, the woven material comprises a plastic or fabric.

[0020] In an embodiment of the invention, the woven material comprises polypropylene.

[0021] In an embodiment of the invention, the woven material comprises polyethylene.

[0022] In an embodiment of the invention, the woven material comprises a composite. Preferably the composite comprises polypropylene and polypropylene.

[0023] In an embodiment of the invention, the flexible tubing comprises an inner layer which comprises the internal surface and is comprised of polyethylene.

[0024] In an embodiment of the invention, the internal surface comprises a lining film.

[0025] According to a second aspect of the invention, there is provided a blast hole liner comprising a length of flexible tubing, wherein the internal surface of said flexible tubing is coated with a material which enables an increased feedrate of filling material into the tubing.

[0026] In an embodiment of the invention, the filling material comprises an explosive slurry.

[0027] In an embodiment of the invention, the filling material comprises ANFO.

[0028] According to a third aspect of the invention, there is provided a method of lining a blast hole with a liner, wherein the liner according to one of the previous aspects is selected for installation in a deviated or inclined from vertical blast hole. [0029] According to a fourth aspect of the invention, there is provided a method of manufacturing a blast hole liner by coating an internal surface of the liner with a lubricant.

[0030] In an embodiment, the method comprises rolling the coated blast hole liner.

[0031] In an embodiment, the method comprises transporting the coated blast hole liner to site.

[0032] In an embodiment, the method comprises inserting the coated blast hole liner into a blast hole.

[0033] In an embodiment, the method comprises feeding an explosive into the coated blast hole liner when the liner is inside the blast hole.

[0034] According to a fifth aspect of the invention, a method of filling a blast hole liner with a filling material, wherein the liner comprises an internal surface coated with a lubricant and is disposed in a deviated blast hole.

[0035] Throughout the specification and claims, unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Description of Drawings

[0036] In order to provide a better understanding of the present invention embodiments will now be described may be described, by way of example only, with reference to the drawings, in which:

Figure 1 is a perspective view of a blast hole liner in a roll form showing a pair of opposed gussets.

Figure 2 is a cross sectional view of an installed lubricated blast hole liner with a zoomed excerpt of the side of the liner and blast hole. Detailed Description

[0037] Referring to Figure 1 , there is shown an example of a blast hole liner 10. The blast hole liner 10 is flexible and comprises an internal surface 18 coated with a lubricant 6, preferably an oil in liquid form. In an embodiment the blast hole liner 10 comprises a lay-flat configuration 12, with a pair of opposed gussets 14 and 16 each in the form of inwardly extending folded portion. When the blast hole liner 10 is folded into a lay-flat configuration, the width of the liner is substantially narrower than the diameter of the blast hole 4.

[0038] In this embodiment the lubricant is an organic oil, such as a vegetable oil. The vegetable oil may be a bean oil. The organic oil may be refined or unrefined. It will be appreciated that alternative lubricants may be used provided they are not reactive with the formation 2 through which the blast hole 4 traverses, the blast hole liner 10 internal surface 18, or the explosives being loaded into the blast hole liner. Alternative lubricants 6 typically comprise a hydrocarbon such as a grease or an oil. The lubricant 6 enables a higher feedrate of filling material in blast hole liners 10 installed in blast holes 4 which deviate from vertical or substantially vertical.

[0039] The opposed gussets 14 and 16 allow installed blast hole liner 10 to expand and conform to accommodate various diameters of blast holes 4. In some embodiments, the opposed gussets 14 and 16 may overlap each other in the lay-flat configuration. The opposed gussets 14 and 16 enable an easy deployment of blast hole liner 10 into the blast hole 4 as the width of the blast hole liner 10 with opposed gussets 14 and 16 is shorter than the diameter of the blast hole 4. Lubricant 6 coats one or more of the inner folded surfaces formed by the opposed gussets 14 and 16.

[0040] The outer layer of the blast hole liner 10 comprises, for example, a woven material of plastic or fabric comprising polypropylene. The blast hole liner 10 comprises an internal surface layer 18 comprising polyethylene. It will be appreciated that alternative internal surface 18 materials may be used and can comprise of any suitable material which is not reactive with the chosen lubricant 6 and/or the explosives being loaded into the blast hole liner 10.

[0041] Referring to Figure 2, the blast hole liner 10 comprising a flexible tubing with an internal surface 18 coated in lubricant 6 is installed in a blast hole 4. The blast hole 4 is drilled into a formation 2 where planned blasting activity is to be conducted. The width of the blast hole liner 10 when in the lay-flat configuration enables easier installation into the blast hole 10. As the filling material is pumped into the blast hole liner 10, the opposed gussets 14 and 16 expand the blast hole liner 10 to enable a single size blast hole liner 10 to be used in a plurality blast holes 4 with varying diameters. The blast hole liner 10 diameter increases as it is filled until the outer surface of the blast hole liner engages with the blast hole 4. [0042] In an embodiment the blast hole liner 10 may be manufactured through a process comprising extrusion. Alternatively, a blast hole liner 10 may be woven using a circular loom. Subsequently the lubricant 6 is applied to the internal surface 18, or surfaces, by a suitable method, for example, spraying. Once the lubricant has been applied the blast hole liner 10 can be rolled for transportation to site or storage.

[0043] Once on site, the blast hole liner 10 is unwound to a desired length determined by the depth of the blast hole 4. A desired amount of blast hole liner 10 is measured and cut to prepare for installation into a blast hole 4. A blaster takes one end of the measured blast hole liner 10 and closes/seals the end, such as by thermal sealing or ties a knot, roughly a meter from an end. A quantity of sand, drill cuttings or other particulate material is fed into the end closest to the knot and another seal or knot may be tied at the same end enclosing the sand, drill cuttings or other particulate material in a length of the blast hole liner 10. This creates a weight at the end which makes it easier to lower the blast hole liner 10 while installing in the blast hole 4. The weighted end of the blast hole liner 10 is lowered into blast hole 4 to the bottom of the hole. Alternatively, the measured length is not cut before insertion into the blast hole. The weighted end is lowered into the blast hole and when at the bottom the liner is cut leaving a small amount free at the open end of the blast hole, into which the explosive can be loaded.

[0044] Once lowered to the bottom of the hole, typically at a later time, explosives are loaded into the blast hole liner 10. Typically, Ammonium Nitrate Fuel Oil (ANFO) (or variants known to those skilled in the art) is used as the explosive. Particularly in blast holes 4 that are deviated, the explosives being loaded are not assisted by gravity (or as much by) in the same manner as explosives would in a blast hole 4 that is relatively vertical. The lubricant 6 causes the explosives to more readily flow through the blast hole liner 10 thereby enabling a faster feedrate of explosives, particularly in blast holes 4 which are deviated. Once the blast hole liner 10 installed in the blast hole 4 is filled with explosives, priming and detonation accessories, it can then be closed off and stemming is added in accordance with standard practices.

[0045] The skilled reader would readily appreciate the nature of the materials appropriate for making the components of the embodiments of the arrangements described herein. Modifications and variations as would be apparent to the skilled addressee are intended to be covered by the accompanying claims.