Field of the invention The invention relates to a shaft sinking apparatus and method for sinking a shaft in a mining operation.

Background to the Invention The inventors are aware of standard shaft sinking methods and the apparatus used in such methods, for example, as described by R Tatia in 2005 (http://en.wikipedia.org/wiki/Shaft construction#Applications of Shafts: .28R. Tatia 2005.2 9 retrieved on 29 July 2012). Tatia divides the operations for sinking a shaft into three parts:

1.Reaching up to the rock head

2. Sinking through the rock

3. Sinking through the abnormal difficult ground, if any, using special methods A typical sinking cycle includes the following operations: (R. Tatia 2005)

Drilling

Blasting

Mucking and hoisting

Support or shaft lining

Auxiliary operations such as:

1. Dewatering

2. Ventilation

3. Lightning or illumination

4. Shaft centering

Drilling

There are three typical types of cuts:

1. Wedge cut

2. Step cut

3. Pyramid cut l 1 and 2 are common drilling that are used and in rectangular shafts. Wedge cut is used most of the time. Pyramid cut is often used in the circular ones. Step cut is adopted if water is high and the shaft is of a large cross section. Blasting

In practice, at the bottom of shaft is usually full of water during sinking, therefore, high density, water-resistant explosives are used to break the rock which then has to be removed from the bottom of the developing shaft.

Lashing and mucking

Lashing is made for the loading of muck into a conveyance for its disposal. This activity is a time consuming activity due to presence of water, personnel, and generally limited space.

Support or shaft lining

There are two types of lining,

1. Temporary

2. Permanent

The type of water and strength of the rock and soil layer where sinking operation is done determine which option to select. Therefore, in some cases, temporary support is not adopted, while in others it becomes essential to protect the crew and equipment from any side fall.

The permanent lining can be made of bricks, concrete blocks, monolithic concrete, shotcrete and cast iron tubing. The inventors believe that both personnel safety and the efficiency of the operation can be improved over known methods and apparatus by adopting the shafy sinking apparatus and method as described herein below.

Summary of the Invention

Thus, in accordance with a first aspect of the invention, there is provided a shaft sinking apparatus, which apparatus includes at least the following components: a platform having at least three decks, which platform is similar in construction and design to those currently in use in the shaft sinking operation and known as a sinking stage; - a vertically displaceable or extendible boom assembly;

a gear driven slew gear for attachment and operation of said boom assembly, which slew gear permits full 360 degree rotation;

an excavator digging arm and bucket assembly mounted at an end region of said boom assembly or which is displaceable along said boom assembly and which, in use, operates at the bottom zone of the shaft being sunk;

one or more skips for receiving material extracted using the digging arm and bucket assembly and displacing same from a working zone of the apparatus;

one or more extended fixed guidance systems extending from the working zone of the apparatus at the bottom zone of the shaft being sunk, to an approximate distance of some 5 - 12 m below the lowest deck of the platform; and

a vacuum apparatus used in conjunction with the telescopic boom assembly and excavator arm and bucket assembly which, in use, collects and transfers fine material left in a bottom zone of the shaft after loading operations into skips.

The vacuum apparatus may be a heavy duty industrial vacuum cleaner apparatus used to clear and transfer fine material left in the bottom zone of the shaft after loading operations into skips

The platform may have 5 or more decks.

The boom assembly may be telescopingly extendible.

The boom assembly may be vertically displaceable by means of a rack and gear, a linear motor, a hydraulic ram, or the like.

The vacuum apparatus may include a suction hose and nozzle which may be engaged by the bucket and in this way lowered to the shaft bottom zone in order to commence vacuuming operations.

There may be two fixed guidance systems or fixed guide assemblies carried below the lowest deck of the platform but this could be increased to four or more. The purpose of these guides is to provide a means of guiding the broken rock conveyances known, or skips, into the bottom limits of the sinking shaft excavation for temporary consolidation of loads and then hoisted to surface. A second function of the fixed guides is to support one or more, typically two, hydraulic drilling carriages that are brought down into the shaft bottom zone after the loading operation is complete so that drilling of blast holes into the floor of the excavation can be carried out. According to a second aspect of the invention, there is provided a shaft sinking apparatus, which apparatus includes at least the following components:

a platform having at least three decks, which platform is similar in construction and design to those currently in use in the shaft sinking operation and known as a sinking stage; a vertically displaceable or extendible boom assembly;

- a gear driven slew gear for attachment and operation of said boom assembly, which slew gear permits full 360 degree rotation;

an excavator digging arm and bucket assembly mounted at an end region of said boom assembly which, in use, operates at the bottom zone of the shaft being sunk;

one or more skips for receiving material extracted using the digging arm and bucket assembly and displacing same from a working zone of the apparatus to an intermediate zone where the skips are emptied into a holding vessel, termed a measuring flask;

one or more skips for receiving material from the measuring flask and for displacing said material out of the shaft for disposal;

one or more extended fixed guidance systems extending from the working zone of the apparatus at the bottom zone of the shaft being sunk, to an approximate distance of some 5 - 12 m below the lowest deck of the platform; and

a heavy duty industrial vacuum cleaner apparatus used in conjunction with the telescopic boom assembly and excavator arm and bucket assembly in order to clean and transfer fine material left in a bottom zone of the shaft after loading operations into skips.

The platform may have 5 or more decks.

There may be two sizes of skips used in this process; firstly there may be two small skips hereafter termed the 'mini-skips' which will transport broken rock which has been loaded into these mini-skips with the excavator boom assembly up to the top portion of the platform whereafter the small skips will discharge this broken rock into a receptacle, termed a measuring flask. Once the measuring flask has been filed up to its designed capacity by using the small skips, two larger skips are used to transport the contents of the measuring flask up to the surface where it will be discharged via a conventional tipping system into an intermediate storage bin from whence it will be loaded into trucks or onto a conveyor system for disposal on surface. There may be two or more fixed guidance systems or fixed guide assemblies carried below the lowest deck of the platform but this could be increased to four or more. The purpose of these guide assemblies is to provide a means of guiding the broken rock conveyances known, or skips, into the bottom limits of the sinking shaft excavation for temporary consolidation of loads and then hoisted to surface.

A function of the fixed guide assemblies is to support the two hydraulic drilling carriages that are brought down into the shaft bottom after the loading operation is complete so that drilling of the blast holes into the floor of the excavation can be carried out.

Another function of the fixed guide assemblies may be to lock drilling carriages into position when drilling.

The Heavy duty industrial vacuum cleaner apparatus used in conjunction with the telescopic boom assembly and excavator boom and bucket assembly in order to clean and transfer all fine material left after loading operations into the skips includes a suction hose and nozzle which will be engaged by the bucket and in this way lowered to the shaft bottom in order to commence vacuuming operations. Description of Embodiments of the Invention

The invention will now be described, by way of non-limiting example only, with reference to the accompanying diagrammatic drawings. Example 1

The operational method of a shaft sinking apparatus of the invention may be described in a number of steps, however, the particular indicated steps are not intended to limit the operational method of the invention but are merely presented to illustrated the operation thereof to the reader and some of the steps may in practice be omitted, combined, or additional steps may be required either before, after, or during any illustrated step, or all the steps.

The figures illustrating each of the steps 1 to 20 are numbered Figures 1 to 20. The figures show a shaft sinking site 10 into which a multi deck shaft sinking apparatus or stage 12 is lowered and the shaft is then excavated in accordance with the steps set out below. The shaft sinking apparatus or stage 12 apparatus includes the following components:

a platform 1 having a number decks 16, which platform 14 is similar in construction and design to those currently in use in the shaft sinking operation and known as a sinking stage;

a vertically displaceable or extendible boom assembly 18;

- a gear driven slew gear 20 for attachment and operation of said boom assembly 18, which slew gear permits full 360 degree rotation;

an excavator digging arm and bucket assembly 22 mounted at an end region of said boom assembly 18 or which is displaceable along said boom assembly 18 and which, in use, operates at the bottom zone of the shaft being sunk;

- one or more skips 24 for receiving material extracted using the digging arm and bucket assembly 22 and displacing same from a working zone 26 of the apparatus;

one or more extended fixed guidance systems 28 extending from the working zone of the apparatus at the bottom zone of the shaft being sunk, to an approximate distance of some 5 - 12 m below the lowest deck 30 of the platform 14; and

- a heavy duty industrial vacuum cleaner apparatus 32 used in conjunction with the telescopic boom assembly 18 and excavator arm and bucket assembly 22 in order to clean and transfer fine material left in the bottom zone of the shaft after loading operations into the skips 24. For reasons of clarity all the reference numerals are not repeated in each step explanation herebelow.

STEP 1 Lowering of the multi deck sinking stage 12 into the shaft bottom after a blast.

As can be observed the telescopic boom assembly 18 is carried off the lower deck 30 and attached to this boom is the excavator/backhoe assembly 22. STEP 2

Initial positioning of the stage 12 above the muck pile at shaft bottom. Note the telescopic boom 18 in the retracted position.

Note also that the telescopic boom 18 is carried at two points; the upper being the slew assembly which affords 360 degrees of rotation movement to the boom assembly about the centre axis. The second point is the stabilising and centralising guide bearing assembly mounted on the lowest deck 30.

STEP 3

Final positioning and stabilisation of the stage 12 in the shaft bottom prior to loading operations taking place.

Note that the boom 18 has started extending.

STEP 4

Preparing to dig into the muck pile. Note the descent of the skip 24 through the stage 12 on its way to the extended guides 28 below the bottom deck of the stage.

STEP 5 Commencement of digging (mucking) operations.

It must be noted that the boom 18 and excavator arm assembly 22 operate in unison although each component can be operated independently STEP 6

Skip 24 in position for shaft bottom loading and the excavator boom 18 is fully retracted in order to allow tipping of the contents of the loading bucket 22 into the opening at the top of the skip 24.

STEP 7 Tipping into the skip 24. Skip 24 capacity can vary between 3 tons and 18 tons and will be dependent on final designs as will the size of the excavator boom and bucket 22 and the telescopic boom 18. STEP 8

Once the skip 24 is fully loaded to design capacity the skip 24 departs to surface via the winding plant and the next empty skip 24 is brought to shaft bottom in order to be loaded with the excavator boom and bucket 22.

STEP 9

Further mucking and loading with the excavator boom 22 now into the second skip 24.

STEP 10

Further mucking and loading with the excavator boom and bucket 22 now into the second skip 24.

STEP 11

Muck pile is now depleted with only fine material left on the shaft bottom floor STEP 12

Vacuum unit 32 is now shown on the stage. This was previously omitted due to allowance for clarity in the previous sketches. Note that the nozzle unit is engaged by means of the bucket 22 in order for lowering to the shaft bottom floor.

STEP 13 Vacuuming operations 32 in progress with the material being deposited into the skip 24. STEP 14 Retracting and stowing of the nozzle and vacuum pipe 32. STEP 15

Lowering below the skip 24 of the drilling module 34 which carries the drills. STEP 16 Parking of the drilling module 34 and locking into position prior to the commencement of drilling operations.

STEP 17 Unhitching of the drill module 34 from the skip 24 and lowering of the second module 36 to shaft bottom from surface.

STEP 18 Lowering of the second drilling module 36 into position below the stage. STEP 19

Commencement of drilling operations with second module 36 simultaneously with first unit 34.

STEP 20

Drill units 34, 36 shown in extended positions.

Example 2

Again, the operational method of shaft sinking apparatus of the invention may be described in a number of steps, however, the particular indicated steps are not intended to limit the operational method of the invention are merely presented to illustrated the operation thereof to the reader and some of the steps may in practice be omitted, combined, or additional steps may be required either before, after, or during any illustrated step, or all the steps. The figures illustrating each of the steps 1 to 20 are numbered Figures 21 to 40.

The figures show a shaft sinking site 110 into which a multi deck shaft sinking apparatus or stage 1 12 is lowered and the shaft is then excavated in accordance with the steps set out below.

The shaft sinking apparatus or stage 112 includes the following components:

a platform 114 having several decks as shown, which platform is similar in construction and design to those currently in use in the shaft sinking operation and known as a sinking stage;

a vertically displaceable or extendible boom assembly 1 18;

a gear driven slew gear 120 for attachment and operation of said boom assembly 1 18, which slew gear permits full 360 degree rotation;

- an excavator digging arm and bucket assembly 122 mounted at an end region of said boom assembly 1 18 which, in use, operates at the bottom zone of the shaft being sunk; one or more skips 124 for receiving material extracted using the digging arm and bucket assembly 122 and displacing same from a working zone 126 of the apparatus to an intermediate zone 125 where the skips 124 are emptied into a holding vessel, termed a measuring flask 127;

one or more skips 123 for receiving material from the measuring flask 127 and for displacing said material out of the shaft for disposal;

one or more extended fixed guidance systems 128 extending from the working zone 126 of the apparatus at the bottom zone of the shaft being sunk, to an approximate distance of some 5 - 12 m below the lowest deck of the platform; and

a heavy duty industrial vacuum cleaner apparatus 130 used in conjunction with the telescopic boom assembly 1 8 and excavator arm and bucket assembly 122 in order to clean and transfer fine material left in the bottom zone of the shaft after loading operations into skips 123, 124.

Again, for clarity reasons, all the reference numerals are not repeated in each of the step explanations herebelow.

STEP 1

Lowering of the multi deck sinking platform 112 into the shaft bottom after the blast. As can be observed the telescopic boom assembly 1 18 is carried off the lower deck and attached to this boom is the excavator/backhoe assembly 122.

STEP 2

Initial positioning 112 of the stage above the muck pile at shaft bottom.

Note the telescopic boom 1 18 in the retracted position. Note also that the telescopic boom 118 is carried at two points; the upper being the slew assembly which affords 360 degrees of rotation movement to the boom assembly about the centre axis.

The second point is the stabilising and centralising guide bearing assembly mounted on the lowest deck.

STEP 3

Final positioning and stabilisation of the stage 112 in the shaft bottom prior to loading operations taking place.

Note the two 'Mini-skips' 124 in position.

Note that the boom 1 18 has started extending.

STEP 4

Preparing to dig into the muck pile. Note the descent of the skip 124 through the stage 1 12 on its way to the extended guides 128 below the bottom deck of the stage.

STEP 5

Commencement of digging (mucking) operations.

It must be noted that the boom 118 and excavator arm assembly 122 operate in unison although each component can be operated independently. STEP 6

Skip 124 in position for shaft bottom loading and the excavator boom 1 8 is fully retracted in order to allow tipping of the contents of the loading bucket 122 into the opening at the top of the skip.

STEP 7 Tipping into the skip 24.

Mini-Skip 124 capacity can vary between 3 tons and 10 tons and will be dependent on final designs. As will the size of the excavator boom and bucket 122 and the telescopic boom 1 18. STEP 8

Once the Mini-skip 124 is fully loaded to design capacity the skip departs to the loading position of the flask 127, via the Winding Plant, and proceeds to tip the load whilst the next empty skip 124 is brought to shaft bottom in order to be loaded with the excavator boom and bucket 122.

STEP 9

Further mucking and loading with the excavator boom 1 18 now into the second skip 124. Note the large skip 123 moving into position to accept the load from the flask 127. STEP 10

As per previous step. Large skip 127 in position to receive load. STEP 11

Muck pile is now depleted with only fine material left on the shaft bottom floor STEP 12

Vacuum unit 130 is now shown on the stage. This was previously omitted due to allowance for clarity in the previous sketches. Note that the nozzle unit is engaged by means of the bucket 122 in order for lowering to the shaft bottom floor.

STEP 13 Vacuuming operations in progress with the material being deposited into the skip. STEP 14

Retracting and stowing of the nozzle and vacuum pipe 130.

STEP 15

Lowering below the skip of the drilling module 132 which carries the drills. STEP 16

Parking of the drilling module 132 and locking into position prior to the commencement of drilling operations. STEP 17

Unhitching of the drill module 132 from the skip 124 to permit lowering of the second drilling module 134 to shaft bottom from surface.

STEP 18

Lowering of the second module 134 into position below the stage. STEP 19 Commencement of drilling operations with second module 134 simultaneously with the first module 132. STEP 20

Drill units 132 , 134 shown in extended positions. Thus, the invention as illustrated, has the advantage of reducing the need for personnel to be down at the bottom of the shaft and in harms way. Furthermore, it improves efficiency and the rate at which the shaft can be sunk.