WO2002075115A1

WO2002075115A1 - A method of sinking a shaft

Info

Publication number: WO2002075115A1
Application number: PCT/IB2002/000729
Authority: WO
Inventors: Barry Anthony Hodgkinson; Marthinus Johannes Potgieter
Original assignee: Brandrill Torrex (Proprietary) Limited
Priority date: 2001-03-13
Filing date: 2002-03-13
Publication date: 2002-09-26

Abstract

A method of sinking a shaft includes the steps of: a. drilling a plurality of holes in a required configuration for use with the small charge blasting technique; b. loading at least some of the holes with a charge comprising one of a propellant and an explosive mixture thereof in accordance with the small charge blasting technique being used; c. breaking the rock using the small charge blasting technique; and d. removing at least some rock broken by a previous small charge blast simultaneously with at least one of steps a, b and c.

Description

SHAFT SINKING

INTRODUCTION TO THE INVENTION

This invention relates to a method of sinking shafts and the like and to equipment therefore.

BACKGROUND TO THE INVENTION

While the invention is described with particular reference to the mining industry this should not be construed as limiting the application in any way.

Conventionally the sinking of shafts in the mining industry is effected using well known explosive blasting techniques. Blasting holes are drilled in the shaft floor, charged with explosive. Once and after the stage has been moved back up the shaft for + 60m, the explosive rounds are set off, and after a minimum re entry period of 30 minutes has been adhered to the rock is removed using grabs, 630 loaders, brutus loaders, or the like into kibbles which are then hoisted to surface. This constitutes a cyclic operation in which each activity forms part of the critical path. Drilling of the holes and removal of the rock is facilitated by way of a stage or stages above the shaft floor. This stage is suspended using stage ropes and lowered/raised by means of a stage winder. From this stage rock loading equipment (eg a cactus grab) may be suspended which is used to load the rock into a kibbles passing through kibble holes in the stage and travelling up and down the shaft.

Insofar as loading is concerned it has also been known to pivotally suspend an articulated bucket loading device from a central point of the stage. The operator and the device can thus swivel through about 360 degrees for more effective cleaning and loading.

One of the major problems with the known system is that the stage and equipment must be removed from the working area during blasting otherwise it may be damaged. It will be appreciated that considerable time is spent manoeuvring this equipment with resultant delays in the recommencement of drilling, cleaning and loading operations.

A further delaying factor is associated with the procedure for lining the shaft. This is generally effected by placing suitable shuttering in position and casting concrete. It is apparent that during this process the stage cannot travel between working and removed positions.

In mining and civil excavation work, small charge blasting or controlled fracture techniques are being introduced as alternatives to conventional drill-and-blast, mechanical breaking, chemical expansion agent and in some cases hand methods. The term "small-charge blasting" as used herein includes any excavation method where relatively small amounts of an energetic substance (typically a few kilograms or less) are consumed for each hole in a rock breaking sequence as well as any method in which a pressurised fluid such as a gas, or foam, is sealed in the bottom of a drill hole to initiate and propagate a fracture. The term "sealing" refers to the partial or total blockage of the hole to impede the escape of the pressurised fluid from the hole.

In many small charge blasting methods, a hole is drilled into the rock to be broken and a propellant or explosive cartridge and a stemming material or stemming bar (or alternatively gun-like barrel) inserted into the hole depending on the nature of the process. A pressurised working fluid, such as a gas, water, or foam, is released rapidly into a portion of the hole, usually the bottom portion. The pressurised fluid is typically generated by combustion of a propellant or explosive source, by electrical discharge into a conductive fluid, by inducing a rapid change or by mechanical compression of a working fluid. The stemming bar, stemming material or barrel seals and stems the pressurised fluid in the hole bottom and thereby causes fracturing of the rock. Small charge blasting can be highly mechanised and automated to increase productivity, can permit excavation machinery to remain near the face due to reduced fly rock discharge, and can have a seismic signature that is relatively small because of the small amount of blasting agent used in the blasting sequence.

OBJECT OF THE INVENTION

An object of this invention is to provide a new method of sinking shafts which may be continuous or semi-continuous in nature with the benefits that various aspects of the process can continue without causing unacceptable delays. It is also an object of the invention to provide equipment for achieving this. SUMMARY OF THE INVENTION

According to the invention a method of sinking a shaft comprises breaking the rock of the floor of the shaft using at least one small charge blasting technique and removing the broken rock.

Further according to the invention the small charge blasting technique is that known as the penetrating cone fracture (PCF) technique and a propellant is used.

Still further according to the invention the method is at least semi- continuous and comprises the sub steps of:

a. drilling a plurality of holes in a required configuration for use with the small charge blasting technique;

b. loading at least some of the holes with a charge comprising one of a propellant and an explosive mixture thereof in accordance with the small charge blasting technique being used;

c. breaking the rock using the small charge blasting technique; and

d. removing at least some rock broken by a previous small charge blast simultaneously with at least one of steps a, b and c.

Still further according to the invention the steps a, b, c and d are repeated on a continuous or semi-continuous basis.

Still further according to the invention a portion of the lining of the shaft is at least partially made during one or more of steps a, b, c and d of at least one repitition. Still further according to the invention the method includes the steps of:

e. stabilising the side wall of the shaft including drilling suitable holes therein for rock anchors.

According to a further aspect of the invention equipment for sinking shafts comprises:

a stage adapted to be adjustably suspended in a shaft at a working position with respect to the floor thereof;

a mechanism for releasably locking the stage with respect to the side wall of the shaft; and

rock removal equipment mounted to the lower side of the stage to pivot about the axes of the platform or an axis parallel thereto, the equipment at least including means for at least partially effecting small charge blasting.

Further according to this aspect of the invention the equipment includes other equipment associated with the stage including equipment for drilling support, barring sidewall, shotcreting, loading and charging, and broken rock loading means.

Still further according to this aspect of the invention the broken rock loading means is a loading scoop on an articulated arm, and the means for at least partially effecting small charge blasting includes a first rock drill and hole indexing apparatus.

Still further according to the invention the first rock drill and indexing mechanism may be removably mounted to an articulated arm. Still further according to the invention the rock removal equipment may include a rock drill for drilling anchor holes in the side wall of the shaft, and the rock drill may be removably mounted to an articulated arm or docked in a docking station therefore associated with the stage.

Still further according to the invention the rock removal equipment may include a control cabin for an operator.

Still further according to the invention the shaft sinking equipment includes at least one hoist including at least one bucket into which broken rock may be loaded for removal, the hoist/s passing through an aperture/s or kibble holes in the stage.

Still further according to the invention the shaft sinking equipment includes shaft lining apparatus associated with the stage, the shaft lining apparatus including a plurality of radially movable shutters at the side of the stage.

BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment and example of the invention described for illustrative purposes only, follows with reference to the accompanying drawings in which:

FIG. 1 is a sectional elevation through the bottom of the vertical shaft and showing shaft sinking equipment according to the invention in side view with the shovel/excavator in use.

FIG. 2 is a side view of the shaft sinking equipment of figure 1 with the small charge blasting drilling equipment in use. FIG. 3 is a side view of the shaft sinking equipment of figures 1 and 2 with the horizontal side wall drill in use.

FIG. 4 is a side view of the shaft sinking equipment of figures 1 to 3 with the side wall drill being docked and the small charge blasting equipment mounted.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

In this embodiment of the invention shaft sinking equipment (1) is described in conjunction with a method of shaft sinking according to the invention.

The method of shaft sinking relies on small charge blasting techniques and specifically the technique known as penetrating cone fracture (PCF) which uses small charges of propellant material to break or split rock off on a main body of rock.

The method is particularly suited to semi-continuous or continuous operation in the sinking of vertical shafts in mines and the like.

In essence the shaft sinking method comprises the following steps:

a. Firstly, a plurality of substantially parallel holes (2) are drilled into the floor at the bottom (3) of a shaft indicated generally by numeral (4) and having a generally cylindrical side wall (5).

b. The holes or at least some of them are charged in known manner with a propellant cartridge and suitable stemming for example a particulate stemming material. The cartridges are wired in known manner to a blasting control box. c. The propellant charges are detonated in known manner and in a determined sequence to split the rock.

d. While steps b and c are taking place, that is while the holes are being loaded with propellant charges, and stemming material and while blasting is taking place the broken rock (6) is excavated using excavating equipment described below and loaded into the skip (7) of a suitable hoist mechanism (8). The rock removal equipment could include vacuum or suction type removal equipment.

Once the broken rock has been loaded more holes may be drilled this may be even while the previous holes are being loaded with cartridges and/or blasting is taking place.

Because of the nature of propellants and small charge blasting techniques it is not necessary to remove equipment during the blasting process and for this reason the method also includes the simultaneous stabilisation of the side wall (5) and the casting of a concrete lining (9). This stabilisation may include the drilling (4) and installation of rock anchors (not shown) in the side wall (5).

The shaft sinking equipment proposed to effect the above method is shown in figures and comprises the multi-level stage indicated generally by numeral 10. The drawing shows only the lower portion of the stage. The stage (10) is suspended in known manner from the top of the shaft so as to be raisable and lowerable in the shaft. It is provided with hydraulic pneumatic or mechanical side wall engaging means for stabilising the stage at a working level in the shaft. The lower level (11) of the stage includes a bottom platform (12) the diameter of which is somewhat less than the diameter of the shaft including the lining thereof.

Passing through this platform and indeed the remainder of the stage are two diametrically disposed apertures (13) or kibble holes which provide passage for the skips or kibbles (7) of the hoists (8). These are raised and lowered in an alternate manner thus while the one kibble (7) is being loaded the other reaches the ground level and is emptied. In this way the two kibbles counterbalance each other to some extent.

Pivotally and co-axially mounted to the lower surface (14) of the platform (12) of the stage (10) is rock removal equipment indicated generally by numeral (16).

A mounting (17) is provided for the equipment (16) and comprises a co-axial cylindrical member (18) terminating in a flat generally horizontal plate (19). A pivot pin (20) projecting through this plate connects to the circular plate (21) of a generally triangular vertical bracket (22).

The equipment (16) mounted to the bracket (22) includes firstly an operator's cabin (23) which is fully enclosed and substantially sound proof and dust proof. It includes ventilation means (not shown) and the various controls necessary for operating the equipment described below.

Also attached to the mounting plate at the lower most apex (23) thereof is an articulated arm having three pivotally connected members (25) and terminating in a scoop (26) to form an excavator. The arms are connected in known manner by hydraulic piston cylinder assemblies to give effect to the movement and operation thereof.

The arm member (25) at the free end of the arm (24) and to which the scoop (26) is attached includes a mounting (27) to which alternatively may be attached a first drill and indexing mechanism (28) for effecting the PCF rock breaking and optionally a larger second drill (29) for drilling into the side wall (5) for the provision of anchor bolts and the like. The mounting (27) for the first drill comprises two spaced parallel linkages pivotally connected to the arm member (25) and incorporating the necessary hydraulic piston and assembles cylinder (not shown) to effect suitable movement thereof.

It is to be noted that when the larger drill (29) is not in use it is docked in a docking station in the platform (13). Figure 4 for example indicates the larger drill (29) in this docking station position.

As mentioned previously the diameter of the stage (10) is less than that of the side wall (5) and the concrete lining (19). This is to accommodate a plurality of shutter members (30) which are located around the circumference of the platform (12) and extend upwardly therefrom substantially the height of the bottom level (11). These shutters (30) are hydraulically activated so as to be able to move towards and away from the side wall (5). When they are moved towards the side wall (5) they are in position to receive concrete to continue casting of the shaft lining (9). Once the concrete has set the shutters may be retracted thereby releasing the lining (9) and allowing the stage (10) to move downwards.

It will be appreciated that the casting process can take place simultaneously with the other processes mentioned that is the drilling small charge blasting and excavating and loading operations. The various operations are shown in the drawings as follows:

Figure 1 shows the excavator scoop (26) being used to load broken rock (6) into the skip (7) of the hoist (8).

Figure 2 shows the indexing and drilling mechanism (28) mounted onto the arm (25) being used to drill a pre-determined configuration of holes into the floor (2) of the bottom (3) of the shaft. Here the scoop (26) is in a folded back or retracted position.

Figure 3 shows the larger drill (29) being used to drill holes into the side wall (5) of the shaft.

Figure 4 shows the larger drill (29) being placed into its docking station.

From which has been described above it may be seen that the invention provides a method and equipment for sinking shafts in a manner which is not subject to the usual delays associated with drill and blast methods.

Other embodiments and applications of the invention are envisaged including the use of other types of small charge blasting techniques.

Claims

1. A method of sinking a shaft comprises breaking the rock of the floor of the shaft using at least one small charge blasting technique and removing the broken rock.

2. A method as claimed in claim 1 in which the small charge blasting technique is that known as the penetrating cone fracture (PCF) technique and a propellant is used.

3. A method as claimed in either of claims 1 or 2 in which the method is at least semi-continuous and comprises the sub steps of:

b. loading at least some of the holes with a charge comprising one of a propellant and an explosive a mixture thereof in accordance with the small charge blasting technique being used;

c. breaking the rock using the small charge blasting technique; and

4. A method as claimed in claim 3 in which the steps a, b, c and d are repeated on a continuous or semi-continuous basis.

5. A method as claimed in either of claims 3 or 4 in which a portion of the lining of the shaft is at least partially made during one or more of steps a, b, c and d of at least one repetition. .

6. A method as claimed in any one of claims 3 to 5 which includes the steps of

7. Equipment for sinking shafts comprises:

- a stage adapted to be adjustably suspended in a shaft at a working position with respect to the floor thereof

- a mechanism for releasably locking the stage with respect to the side wall of the shaft; and

- rock removal equipment mounted to the lower side of the stage to pivot about the axes of the platform or an axis parallel thereto, the equipment at least including means for at least partially effecting small charge blasting.

8. Equipment as claimed in claim 7 in which rock removal equipment includes any of equipment for drilling support, barring sidewall, shotcreting, loading and charging, and broken rock loading means.

9. Equipment as claimed in claim 8 in which the broken rock loading means is a loading scoop on an articulated arm.

10. Equipment as claimed in any of claims 7 to 9 in which the means for at least partially effecting small charge blasting includes a first rock drill and hole indexing apparatus.

11. Equipment as claimed in claim 10 in which the first rock drill and indexing mechanism may be removably mounted to an articulated arm.

12. Equipment as claimed in any of claims 7 to 11 which includes a rock drill for drilling anchor holes in the side wall of the shaft, and the rock drill may be removably mounted to an articulated arm or docked in a docking station therefore associated with the stage.

13. Equipment as claimed in any of claims 7 to 12 which includes a control cabin for an operator.

14. Equipment as claimed in any of claims 7 to 13 which includes at least one hoist including at least one bucket into which broken rock may be loaded for removal, the hoist/s passing through an aperture/s or kibble holes in the stage.

15. Equipment as claimed in any of claims 7 to 14 which includes shaft lining apparatus associated with the stage, the shaft lining apparatus including a plurality of radially movable shutters at the side of the stage.

16. Equipment substantially as herein described with reference to the accompanying drawings.

7. A shaft sinking method substantially as herein described with reference to the accompanying drawings.