AU768956B2

AU768956B2 - Shaft sinking method

Info

Publication number: AU768956B2
Application number: AU59522/00A
Authority: AU
Inventors: Brian Bernard Rodan
Original assignee: Australian Contract Mining Pty Ltd
Current assignee: Australian Contract Mining Pty Ltd
Priority date: 1999-10-21
Filing date: 2000-09-20
Publication date: 2004-01-08
Anticipated expiration: 2020-09-20
Also published as: AU5952200A

Description

P/00/011 28/5/91 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Actual Inventor Address for service is: Australian Contract Mining Pty Ltd Brian Bernard Rodan WRAY ASSOCIATES 239 Adelaide Terrace Perth, WA 6000 Attorney code: WR Invention Title: "Shaft Sinking Method" Details of Associated Provisional Application No: PQ3585 The following statement is a full description of this invention, including the best method of performing it known to me:- -2- 'Shaft Sinking Method' Field Of The Invention The present invention relates to a shaft sinking method. More particularly, the shaft sinking method of the present invention is adapted for use in the sinking of substantially vertical, blind mine shafts.

Background Art The two methods presently used in the sinking of blind mining shafts are widely known as 'full-facing' and 'benching' respectively.

The full-facing method has been utilised to its fullest potential in South Africa, i: 10 where laws allowing concurrent sinking and lining, and the ready availability of a cost effective labour source, have enabled shafts to be sunk at rates two to three times faster than in other countries.

As the name suggests, the full-facing method involves drilling the full shaft face with a plurality of charge holes parallel to the axis of the shaft. Additionally, one or more uncharged relief holes are also drilled parallel to the axis of the shaft, then a burn cut is blasted to advance the shaft. The burn cut is designed to shatter rock into the voids that are initially created by the relief holes. The Sshattered rock is then expelled by the blast to form a cylindrical cavity, thereby advancing the shaft. The shattered rock material is then cleared and the exposed shaft face re-drilled and the cycle repeated.

There is no theoretical limit to the depth at which a burn cut can be blasted, although the operational limit seems to be about ten metres. Typically however, shaft advance rates for each blast are of the order of 2.4 to 3.0 metres, as allowances must be made for effective timing of shifts with the clearance and drilling phases. In South Africa, large well-trained crews comprising 45 to men per shift are optimal in this regard, and daily shaft sinking rates of about 6 metres are achieved using two three metre blasts.

Outside South Africa, benching is generally the 'method of choice', though both methods are extensively used worldwide. The more efficient working conditions generated by benching allow better use of valuable labour. Unlike full facing, benching involves drilling and blasting only half the shaft area at any given time.

The benching method makes use of a 'stripping' or 'drag' cut. A series of parallel rows of holes are drilled into half the shaft face the other half comprising a void.

The holes adjacent the edge of the shaft being substantially parallel to the axis thereof with subsequent holes being increasingly angled away from parallel. By firing the angled holes adjacent the void first, and the parallel holes last, a stripping effect is created in which the shattered rock is thrown into the void.

Generally, the maximum depth in which a bench or stripping cut may be used in a shaft is about 3.4 to 3.7 metres, depending on the diameter of the shaft, with o larger shafts allowing deeper stripping cuts. Given that only half the shaft face is .•.blasted in each cycle, typical shaft advances after each blast when the benching 15 method is employed are approximately half that for full-facing, being about 1.2 to 1.7 metres. However, despite the reduced advance per blast relative to full facing, benching has a number of advantages over the full face method. For example, the drilling and charge up faces are improved as the rock face is always dry. Sockets and misfires are more readily identified. Hand lashing or 20 mucking is minimised by clearing the shattered rock into the void. These operational advantages allow the use of smaller 5 to 10 man crews, more suitable in higher cost labour environments such as Australia, Canada and the USA, and more frequent blasting. Currently, daily shaft sinking rates of about to 5.0 metres are achieved using the benching method.

Further, for safety reasons, blind mining shafts are typically reinforced as they are sunk. Reinforcement may take the form of drilling cable bolts into the walls of the shaft, and spraying concrete thereover. The drilling step in particular is time consuming, and with the sinking methods outlined above, the reinforcement is difficult to perform concurrently with the sinking operations.

-4- The preceding discussion of the background to the invention is intended to facilitate an understanding of the present invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia as at the priority date of the application.

It is one object of the present invention to provide a method that enables greater daily sinking rates than those associated with the prior art, or at least to provide an alternative thereto.

Throughout the specification, 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.

Disclosure Of The Invention In accordance with the present invention there is provided a shaft sinking 15 method, the method comprising the steps of: drilling out a first portion of a shaft-face, drilling a burn cut and drilling an extended round of a predetermined depth into said first portion of the shaft-face; and blasting the burn cut to create a sump occupying the first portion of the shaft face, and a bench occupying a second portion of the shaft face complementary to the first portion of the shaft face, approximately half the predetermined depth above the sump.

Preferably, the first portion of the shaft face corresponds to approximately half of the shaft face.

Preferably, the method further comprises the steps of: mucking to the level of the bench; mucking the sump to a level below that of the bench; and clearing debris from the bench into the sump.

Preferably, the sump is mucked to a level about 0.5 -1.0 metres below that of the bench.

Preferably, the predetermined depth is between 3 and 10 metres. Preferably still, the predetermined depth is between 4 and 8 metres. Further and still preferably, the predetermined depth is between 4 and 6 metres. In a highly specific form of the invention, the predetermined depth is approximately 5 metres.

Preferably, the method of the present invention may further comprise the initial steps of: :drilling out the second portion of the shaft face, drilling a burn cut, and drilling an extended round of approximately half the predetermined depth into said second portion of the shaft-face; and blasting the burn cut in the second portion to create a sump of approximately half the predetermined depth occupying the second portion of the shaft face, such that blasting the burn cut on the first portion of the shaft-face creates a bench occupying the second portion of the shaft-face, and a sump approximately half the predetermined depth below such, S°occupying the first portion of the shaft face.

°oo.

In a preferred form of the invention, drilling is performed by way of a drill jumbo, adapted to drill half a shaft face. Preferably still, drilling is performed by way of a drill jumbo equipped with hydraulic drills. Further and still preferably, the drill jumbo is equipped with advanced hydraulic drills, such as 'rocket' or 'super' type drills.

-6- In accordance with the present invention, there is further provided a shaft sinking method comprising the steps of: drilling out a first portion of a shaft-face, drilling a burn cut, and drilling an extended round to a first predetermined depth into said portion of the shaft-face; blasting the burn cut to create a sump occupying the first portion of the shaft face, and a bench occupying a second portion of the shaft face complementary to the first portion of the shaft face, approximately half the predetermined depth above the sump; mucking to the level of the bench occupying the second portion of the shaft face; mucking the sump to a level below that of the bench occupying the second portion of the shaft face; clearing debris from the bench occupying the second portion of the shaft face into the sump; o* drilling out the bench occupying the second portion of the shaft-face, drilling a burn cut, and drilling an extended round to a second predetermined depth into said portion of the shaft-face; blasting the burn cut to create a sump occupying the second portion of the **shaft face, and a bench occupying the first portion of the shaft face approximately half the second predetermined depth above such; %006 0 0mucking to the level of the bench occupying the first portion of the shaft face; mucking the sump to a level below that of the bench occupying the first portion of the shaft face; -7clearing debris from the bench occupying the first portion of the shaft face into the sump; and repeating the above steps on a cyclical basis, until a desired depth is reached.

The first and second predetermined depths may be identical.

In one form of the invention, the method comprises the following further steps: before the step of clearing debris from the bench occupying the second portion of the shaft face into the sump, drilling reinforcing bolts into a first portion of a shaft wall extending above the first portion of the shaft face; installing a reinforcing medium onto the first portion of the shaft wall whilst drilling reinforcing bolts into a second portion of the shaft wall, the second portion being complementary to the first portion; and after the step of clearing debris from the bench into the sump, installing a reinforcing medium onto the second portion of the shaft wall, whilst performing the step of drilling out the bench occupying the second portion of the shaft-face, drilling a burn cut, and drilling an extended round to a predetermined depth into said portion of the shaft-face.

Preferably, the method comprises the following further steps: before the step of clearing debris from the bench occupying the first portion S: of the shaft face into the sump, drilling reinforcing bolts into the second **jportion of a shaft wall extending above the second portion of the shaft face; installing a reinforcing medium onto the second portion of the shaft wall whilst drilling reinforcing bolts into the first portion of the shaft wall; and after the step of clearing debris from the bench occupying the first portion of the shaft face into the sump, installing a reinforcing medium onto the first portion of the shaft wall, whilst performing the step of drilling out -8the bench occupying the second portion of the shaft-face, drilling a burn cut, and drilling an extended round to a predetermined depth into said portion of the shaft-face.

In one form of the invention, the reinforcing medium is concrete.

Preferably, each portion of the shaft face corresponds to half the shaft face.

Preferably, the sump is mucked to a level about 0.5 to 1.0 metres below that of the bench.

Preferably, the predetermined depth is between 3 and 10 metres. Preferably still, the predetermined depth is between 4 and 8 metres. Further and still preferably, the predetermined depth is between 4 and 6 metres. In a highly preferred form of the invention, the predetermined depth is approximately 5 metres.

In a preferred form of the invention, drilling is performed by way of a drill jumbo, adapted to drill half a shaft face. Preferably still, drilling is performed by way of a drill jumbo equipped with hydraulic drills. Further and still preferably, drilling is performed by way of a drill jumbo equipped with advanced hydraulic drills, such as 'rocket' or'super' type drills.

In one form of the invention, the method is performed within an eight-hour period, enabling three complete shifts to be run in a day. In an alternate form of the *.invention, the method is performed in a twelve-hour period to enable two complete shifts to be run per day. In a further alternate form of the invention, the method is performed in a six-hour period to enable four complete shifts to be run in a day.

•oooi -9- BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described, by way of example only, with reference to two embodiments thereof, and the accompanying drawings in which:- Figure 1 comprises a top view and an axial cross-sectional view of a shaft drilled for a burn cut in accordance with a conventional full-facing method; Figure 2 comprises a top view and an axial cross-sectional view of a shaft drilled for a stripping cut in accordance with a conventional benching method; .i 10 Figure 3 comprises a top view and an axial cross-sectional view of a shaft drilled for a burn cut in accordance with the method of a first embodiment, showing in particular a half of a shaft face drilled for a burn cut; and Figures 4A to 4G illustrate a sequence of steps for sinking a blind, substantially vertical mine shaft in accordance with the first embodiment.

It must be appreciated that the following description of the example is not to limit o the generality of the above description of the invention.

Best Mode(S) For Carrying Out The Invention SFigures 1 and 2 illustrate blasting techniques associated with conventional full facing and benching shaft sinking techniques respectively. In particular, Figure 1 shows that the full shaft face 10 is drilled, with relief holes 12 including a large, extended relief hole 14 occupying the centre of the face 10 for a burn cut. Figure 2 shows that the benching method involves drilling half the shaft face 16 in preparation for a stripping cut. These are to be contrasted with the method of the embodiment that, as can be seen in Figure 3, involves drilling half the shaft face 18, including a plurality of relief holes 22 and a central extended relief hole 24 in preparation for a burn cut.

Figures 4A to 4G show the embodiment being put into effect in sinking a vertical blind mine shaft. As can be seen in Figure 4A, the initial blast is conducted to a depth of approximately 2.5 metres, over a first half 26 of the area of the shaft.

The holes 28 are drilled in the pattern illustrated by Figure 3, by a 'rocket' or 'super' type advanced hydraulic drill. Once the blast is conducted, some of the loose rock 30 is removed by conventional mucking techniques, thereby creating a bench 32 and a sump 34,as can be seen in Figures 46 and C.

Next, holes are drilled to the pattern illustrated in Figure 3 through a second half 36 of the area of the shaft, corresponding to the bench 32, to a depth of approximately 5 metres as can be seen in Figure 4D. Detonation causes loose rock 38 to be thrown toward the sump 34, as can best be seen in Figure 4E. The loose rock 38 is mucked by conventional techniques to create a new bench and a new sump 42, as can best be seen in Figure 4F. Ideally, the loose rock 38 in the sump 42 is mucked to a level approximately 0.5 metres below that of the bench Conveniently, any residual material remaining on the new bench 40 may be pushed into the new sump 42 by known means, such as compressed air, avoiding the need for hand lashing or mucking and improving the blow over 0. cycle. Additionally, the new bench 40 represents a dry and relatively comfortable working surface. This improves the speed of the drilling and charging cycles, as well as worker morale. Further, sockets and misfires are more readily identified.

~As shown in Figure 4G, the new bench 40 is drilled in the pattern illustrated in .I :Figure 3, to a depth of approximately 5 metres. Detonation causes loose rock 44 to be blown into the new sump 42, as shown in Figure 4H. The cycle is repeated until the desired shaft depth is attained.

In accordance with a second embodiment of the present invention, there is provided a shaft sinking method. The shaft sinking method of the second embodiment is similar to the shaft sinking method of the first embodiment and will be described with reference to Figures 4Ato 4F, by way of comparison.

-11 However, the shaft sinking method of the second embodiment includes measures to reinforce the shaft.

The method of the second embodiment is identical to the first embodiment to the point at which the bench 32 is blasted causing loose rock 38 to be thrown toward the sump 34, as is shown in Figure 4E. The majority of the loose rock 38 is mucked by conventional techniques. However, the residual debris on the new bench 40 is not immediately blown over into the new sump 42.

Rather, reinforcing bolts (not shown), such as cable bolts are drilled into a first portion of a shaft wall extending above the bench 40. As concrete is then sprayed over the reinforcing bolts and first portion of the shaft wall, further cable bolts are drilled into a second portion of the shaft wall, above the sump 42. Only then is the residual debris on the bench 40 blown over into the sump 42. After which, concrete is sprayed onto the second portion of the shaft wall, whilst performing the step of drilling out the bench 40, drilling a burn cut, and drilling an extended round to a predetermined depth, as shown in Figure 4G. Accordingly, the sinking of the shaft may resume whilst the reinforcement steps are completed.

9 It is envisaged that, given the speed of advanced hydraulic drilling and the advantageous working conditions of the present invention with regard to mucking, drilling and charging times, a complete 5 metre cycle could be completed within 8 hours. Given that each blast corresponds to a shaft advance :of 2.5 metres, this corresponds to an advance rate of 7.5 metres in a twenty-four hour period.

It is further envisaged that up to 4 blasts, providing 10 metres of shaft advance, per day may be achieved on a particularly well managed project by way of the method of the present invention.

Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention.

Claims

1. A shaft sinking method comprising the steps of: drilling out a first portion of a shaft-face, drilling a burn cut and drilling an extended round of a predetermined depth into said first portion of the shaft-face; and blasting the burn cut to create a sump occupying the first portion of the shaft face, and a bench occupying a second portion of the shaft face complementary to the first portion of the shaft face, approximately half the predetermined depth above the sump. 10 2. A method according to claim 1 wherein the first and second portions of the *shaft face comprise complementary halves of the shaft face. A method according to either claim 1 or claim 2 comprising the additional steps of: .*"mucking to the level of the bench; OV. 15 mucking the sump to a level below that of the bench; and clearing debris from the bench into the sump.

4. A method according to claim 3 wherein the sump is mucked to a level about -1.0 metres below that of the bench. A method according to any one of the preceding claims wherein the predetermined depth is between 3 and 10 metres.

6. A method according to any one of the preceding claims wherein the predetermined depth is between 4 and 8 metres. -13-

7. A method according to any one of the preceding claims wherein the predetermined depth is between 4 and 6 metres.

8. A method according to any one of the preceding claims wherein-the predetermined depth is approximately 5 metres.

9. A method according to any one of the preceding claims further comprising the initial steps of: drilling out the second portion of the shaft face, drilling a burn cut, and drilling an extended round of approximately half the predetermined depth into said second portion of the shaft-face; and blasting the burn cut in the second portion to create a sump of approximately half the predetermined depth occupying the second portion of the shaft face, such that blasting the burn cut on the first portion of the shaft-face creates a bench occupying the second portion of the shaft-face, and a sump approximately half the predetermined depth below such, occupying the first portion of the shaft face. method according to any one of the preceding claims wherein the drilling is performed by way of a drill jumbo, adapted to drill half a shaft face.

11.A method according to claim 10 wherein the drilling is performed by way of a drill jumbo equipped with hydraulic drills.

12.A method according to claim 11 wherein the drill jumbo is equipped with ooooo advanced hydraulic drills.

13.A shaft sinking method comprising the steps of: drilling out a first portion of a shaft-face, drilling a burn cut, and drilling an extended round to a first predetermined depth into said portion of the shaft-face; -14- blasting the burn cut to create a sump occupying the first portion of the shaft face, and a bench occupying a second portion of the shaft face complementary to the first portion of the shaft face, approximately half the first predetermined depth above the sump; mucking to the level of the bench occupying the second portion of the shaft face; mucking the sump to a level below that of the bench occupying the second portion of the shaft face; clearing debris from the bench occupying the second portion of the shaft face into the sump; drilling out the bench occupying the second portion of the shaft-face, drilling a burn cut, and drilling an extended round to a second :predetermined depth into said portion of the shaft-face; blasting the burn cut to create a sump occupying the second portion of the shaft face, and a bench occupying the first portion of the shaft face :.:°:approximately half the second predetermined depth above such; mucking to the level of the bench occupying the first portion of the shaft face; °mucking the sump to a level below that of the bench occupying the first portion of the shaft face; clearing debris from the bench occupying the first portion of the shaft face into the sump; and repeating the above steps on a cyclical basis, until a desired depth is reached.

14.A method according to claim 13 comprising the additional steps of: before the step of clearing debris from the bench occupying the second portion of the shaft face into the sump, drilling reinforcing bolts into a first portion of a shaft wall extending above the first portion of the shaft face; installing a reinforcing medium onto the first portion of the shaft wall whilst drilling reinforcing bolts into a second portion of the shaft wall, the second portion being complementary to the first portion; and after the step of clearing debris from the bench into the sump, installing a reinforcing medium onto the second portion of the shaft wall, whilst performing the step of drilling out the bench occupying the second portion of the shaft-face, drilling a burn cut, and drilling an extended round to a predetermined depth into said portion of the shaft-face. method according to claim 13 or 14 comprising the additional steps of: before the step of clearing debris from the bench occupying the first portion of the shaft face into the sump, drilling reinforcing bolts into the second o• portion of a shaft wall extending above the second portion of the shaft face; e installing a reinforcing medium onto the second portion of the shaft wall whilst drilling reinforcing bolts into the first portion of the shaft wall; and after the step of clearing debris from the bench occupying the first portion the shaft face into the sump, installing a reinforcing medium onto the first of the shaft wall, whilst performing the step of drilling out the bench "!occupying the second portion of the shaft-face, drilling a burn cut, and drilling an extended round to a predetermined depth into said portion of the shaft-face. S

16.A method according to either claim 14 or 15 wherein the reinforcing medium is concrete. -16-

17. A method according to any one of claims 13 to 16 wherein the portions of the shaft face comprise complementary halves of the shaft face.

18. A method according to any one of claims 13 to 17 wherein the sump is mucked to a level about 0.5 to 1.0 metres below that of the bench.

19. A method according to any one of claims 13 to 18 wherein the predetermined depth is between 3 and 10 metres. A method according to claim 19 wherein the predetermined depth is between 4 and 8 metres.

21. A method according to claim 20 wherein the predetermined depth is between 4 and 6 metres.

22.A method according to claim 21 wherein the predetermined depth is approximately 5 metres.

23. A method according to any one of claims 13 to 22 wherein drilling is performed by way of a drill jumbo, adapted to drill half a shaft face.

24. A method according to claim 23 wherein drilling is performed by way of a drill jumbo equipped with hydraulic drills. A method according to claim 24 wherein drilling is performed by way of a drill jumbo equipped with advanced hydraulic drills.

26. A method according to any one of the preceding claims wherein the method is performed within an eight-hour period, enabling three complete shifts to be run in a day.

27. A method according to any one of claims 1 to 25 wherein the method is performed within a six-hour period, enabling four complete shifts to be run in a day. -17-

28. A method according to any one of claims 1 to 25 wherein the method is performed in a twelve-hour period to enable two complete shifts to be run per day.

29. A shaft sinking method substantially as described herein with reference to Figures 3 and 4A to 4H. Dated this Twentieth day of September 2000. Australian Contract Mining Pty Ltd Applicant :Wray Associates Perth, Western Australia S: Patent Attorneys for the Applicant oo