WO2001023709A1

WO2001023709A1 - Position determining device and method

Info

Publication number: WO2001023709A1
Application number: PCT/IB2000/001363
Authority: WO
Inventors: Nico Van Zyl; George Mckinley Langefeld; John Dean Ackerman
Original assignee: De Beers Consolidated Mines Ltd
Current assignee: De Beers Consolidated Mines Ltd
Priority date: 1999-09-27
Filing date: 2000-09-27
Publication date: 2001-04-05
Anticipated expiration: 2002-03-27
Also published as: CA2385762A1; RU2250373C2; AU774035B2; AU7438400A

Abstract

A device for determining a position relative to two layers (14, 16) of different permeability includes at least one fluid outlet (12), means for supplying fluid to the outlet (30), measuring means for measuring the flow rate (36) and/or pressure (38) of the fluid to determine a position relative to the layers. The device is located on an underwater mining machine (82) and the fluid outlet is associated with material removing means (22) of the mining machine. The position determined by the device is the position of an interface between the two layers or the position of one of the layers relative to the other layer so that the depth of the material removing means can be set relative to the two layers in response to the position determined by the device.

Description

POSITION DETERMINING DEVICE AND METHOD

FIELD OF THE INVENTION

THIS invention relates to a position determining device and method More particularly, the invention relates to a device and method for determining a position in two layers of different permeability

BACKGROUND OF THE INVENTION

Underwater mining machines gather material from the seabed and transport the material to a processing vessel operating on the surface The mining machine is generally unmanned, and is controlled by one or more vessel- based operators who are provided with control information from various sensors located on the mining machine

In the underwater mining of alluvial diamonds, the diamonds are typically located in a layer of diamond-bearing gravel which is deposited on a barren clay underburden or footwall One of the main problems associated with mining under these conditions is the difficulty in controiiing the depth of the cutting blade or spade If the cutting blade is too shallow, there is a danger that some of the diamond-bearing gravel will not be mined On the other hand, a cutting blade that is too deep will mine excess clay This clay is then needlessly transported to the surface, where it tends to clog up the processing equipment and reduce the efficiency of the recovery process

It is an object of the invention to provide a device and method for determining a position in two layers of different permeability It is a further object of the invention to provide a device and method for determining a position relative to the diamond-bearing gravel and the clay footwall so that the cutting blade of the mining machine can be maintained at an optimum level just below an interface between the diamond-bearing gravel and the clay footwall.

SUMMARY OF THE INVENTION

According to the invention there is provided a device for determining a position in two layers of different permeability including at least one fluid outlet, means for supplying fluid to the outlet, measuring means for measuring the flow rate and/or pressure of the fluid to determine a position in the two layers.

The device preferably includes a plurality of outlets spaced one above the other. The spaced outlets may increase in discharge capacity from an uppermost outlet to a lowermost outlet. Preferably the spaced outlets comprise an increasing number of nozzles from the uppermost outlet to the lowermost outlet.

The fluid is supplied to the outlet or outlets from a supply conduit which preferably includes pressure regulating means for regulating the pressure in the supply conduit. Preferably fluid flow rate measuring means and pressure measuring means are located in the supply conduit.

The device may be associated with material removing means of a mining machine so that the depth of the material removing means can be set relative to the two layers in response to a position determined by the device. The outlet or outlets may face downwardly relative to the direction of travel of the mining machine In addition, or alternatively, the outlet or outlets may face sideways relative to the direction of travel of the mining machine

According to another aspect of the invention a mining machine includes material removing means having a device as described above associated with the material removing means so that the depth of the material removing means can be set relative to the two layers in response to a position determined by the device

According to another aspect of the invention a mining machine includes material removing means for removing material in an upper layer located on a lower layer having a different permeability to the upper layer, the material removing means having a housing secured thereto, the housing having at least one fluid outlet through which fluid can be discharged, fluid being supplied to the fluid outlet via a conduit having measuring means for measuring the flow rate and/or pressure of the fluid in the conduit in order to determine in which of the two layers the outlet is located so that the depth of the material removing means can be set relative to the two layers

According to another aspect of the invention a method of determining a position in two layers having different permeabilities includes the steps of supplying fluid to at least one outlet located in the layers, measuring the flow rate and/or pressure of the fluid and determining a position in the two layers from the measured flow rate and/or pressure

The method may include the step of discharging fluid from the outlet downwardly onto the layers In addition, or alternatively, the method may include the step of discharging fluid from the outlet substantially parallel to the layers The method preferably includes the step of supplying fluid to a plurality of spaced outlets located one above the other.

The method may include the step of determining the position of an interface between the two layers or the position of one of the layers relative to the other layer from the measured flow rate and/or pressure.

According to another aspect of the invention a method of controlling the depth of material removing means of a mining machine includes the step of setting the depth of the material removing means in response to a position determined according to the method described above.

According to another aspect of the invention a method of controlling the depth of material removing means of a mining machine for removing material in an upper layer located on a lower layer having a different permeability to the upper layer, includes the steps of locating at least one fluid outlet in the material, supplying fluid to the outlet, measuring the flow rate and/or pressure of the fluid, and determining in which of the layers the fluid outlet is located so that the depth of the material removing means can be set relative to the two layers.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a highly schematic diagram illustrating the broad principle of operation of the invention;

Figure 1A shows an enlarged detail of the schematic block diagram of Figure 1 ; Figure 2 shows a highly schematic block diagram illustrating an optimum cutting blade position,

Figure 3 shows a functional block diagram of a first embodiment of a position determining device of the invention,

Figure 4 shows a schematic diagram of an output display and operator control chart forming part of the position determining device,

Figure 5 shows a pictorial view of a manifold forming part of the position determining device,

Figure 6 shows a schematic side view of an underwater mining machine fitted with the manifold of Figure 5,

Figure 7 is a perspective view from the rear of a manifold forming part of a position determining device according to a second embodiment of the invention, and

Figure 8 is a perspective view from the front of the manifold of Figure 7

DESCRIPTION OF EMBODIMENTS

Referring first to Figures 1 and 1A, an outlet manifold 10 having a plurality of fluid outlets 12 1 , 12 2 , 12 3 and 12 4 is shown in highly schematic form The outlets 12 1 and 12 2 vent directly onto a superstrate 14 of gravel, and the outlets 12 3 and 12 4 vent onto a substrate of clay 16 separated from the gravel at an interface 15 The manifold outlets branch from a single fluid conduit 18 which delivers water to the outlets As is clear from the detail in Figure 1A, the gravel particles are permeable, in that water flowing through the outlet 12 2 is able to permeate through the gaps between the individual gravel particles 14 1 , as is shown schematically by arrows 18 In contrast, the clay 16 is relatively impermeable, in that it tends to clog the outlet 12 3 and block the flow of water, as is indicated schematically by arrows 20

The relative permeability of the gravel results in a low pressure high flow condition arising in the outlets 12 1 and 12 2, whereas the relative impermeability of the clay 16 results in relatively high pressure and low flow conditions arising in the outlets 12 3 and 12 4 It is clear that if the entire manifold were moved upwards so that three or more of the outlets vented onto the gravel 14, low pressure and high flow conditions would predominate, whereas if the manifold 10 were lowered to a position in which, say, the outlets 12 2 to 12 4 vented onto the clay, high pressure and low flow conditions would predominate It is thus apparent how, by monitoring the pressure and flow conditions within the single fluid conduit 18, the position of the manifold relative to the gravel and the clay, and hence relative to the interface 15, can be monitored

Referring now to Figure 2, material removing means in the form of a cutting blade or spade 22 forming part of an underwater mining machine is schematically shown having made a cutting pass 24 on the seabed The cutting blade 22 is shown at an optimum level, where it is located just below the interface 15 between the gravel 14 and the clay footwall 16 By positioning the cutting blade just below this interface, mining of the diamond-bearing gravel is assured, whilst at the same time as little clay as possible is mined during the pass The outlet manifolds 10 are bolted onto side plates 26 and 28 on opposite sides of the cutting blade 22 in a position in which they are in continuous contact with the gravel and clay

Referring now to Figure 3, a position determining device 29 of the invention is shown A pump 30 provides water through the supply line 18 The water passes through a 10 micron filter 32 and a pressure reducing station 34 which reduces the water pressure to a typical predetermined pressure and flow rate of 50kPa and 1401s^"1 respectively The water then passes through a flow meter 36 and a pressure transducer 38 which accurately measures the water pressure or the drop therein utilizing a sensing line 39 from the pressure reducing station 34 as a reference The water line 18 leads to the outlet manifold 10

As can more clearly be seen in Figure 5, the outlet manifold 10 comprises a rugged steel housing 40 formed with a series of apertured flanges 42 which allow it to be bolted on to either one of the side plates 26 and 28 of the cutting blade 22 A rugged rubberized insert 44 is bolted onto the side wall of the box 40, and includes a series of elongate projecting horizontal sub-manifolds which define the outlets 12 1 to 12 5 These, respectively, comprise 1 , 2, 3, 4 and 5 individual nozzles 13 in horizontal arrays A series of five nozzles 13 are defined in a lowermost outlet 12 6 in the form of a rubber sub-manifold 48 mounted to the undersurface of the manifold box 40

Signals from the flow meter 36 and pressure transducer 38 are fed to processor circuitry 50 based on the processing vessel The processor circuitry includes a look-up table incorporating pressure and flow parameters corresponding to differing levels of the manifold box relative to the interface, ranging from a situation in which all of the outlets vent onto clay, to one in which all of the outlets vent onto gravel The increasing concentration of nozzles 13 towards the lower sub-manifolds results in greater sensitivity in the area of the outlets 12 5 and 12 6, which level corresponds to the desired level illustrated schematically in Figure 2, in which, say, the outlets 12 6 and possibly the outlets 12 5 are in contact with the clay footwall 16 and the remaining outlets 12 1 to 12 4 vent onto the gravel 14 An output signal from the processor circuitry 50 is fed to a multi-light indicator 52 which is used to indicate the level of the cutting blade. A vessel-based operator 54 observes the display and then manually adjusts the cutting blade level remotely by operating a blade actuator 56 on the undersea mining machine. In an alternative version of the invention, an output signal from the processor circuitry is used directly to operate the actuator 56 to adjust the level of the cutting blade, as is indicated schematically in broken outline at 58.

The display 52 is illustrated in more detail in Figure 4, and includes a bank of lights including two central green lights 60, intermediate upper and lower orange lights 62 and 64, and uppermost and lowermost red lights 66 and 68. The interface 15 is represented by an interface line 70 on a control chart, with upper and lower thresholds being indicated by upper and lower lines 72 and 74 respectively. The position of the blade is indicated graphically at 76, and an auxiliary display 78 may be provided carrying a hold indicator corresponding to the green lights 60, down indicators corresponding to the orange and red lights 62 and 66, and up indicators corresponding to the orange and red lights 64 and 68. These displays are used clearly to instruct the operator to manoeuvre the cutting blade up or down depending on its position relative to the interface 70 and the upper and lower operating thresholds 72 and 74.

Referring now to Figure 6, the outlet manifold 10 is shown mounted to the side of the cutting blade 22 extending from one of a pair of arms 80 forming part of an underwater mining machine 82. It can clearly be seen how the base of the outlet manifold 10 is positioned slightly below the leading edge 22A of the cutting blade with the result that the outlet manifold intrudes into the clay footwall 16, whilst the cutting blade operates at an optimum position at the interface 15 between the gravel superstrate 14 and the clay substrate or footwall 16. Refemng now to Figures 7 and 8 an outlet manifold 10 1 comprises a steel housing 40 1 with an apertured flange 42 1 which allows it to be bolted onto the side plates 26 or 28 of the cutting blade 22 An inclined outlet 12 6 is fastened to the steel housing 40 1 by a cap 84 which is bolted by bolts 86 to the steel housing 40 1 The outlet 12 6 has five nozzles 13 Water is supplied to the five nozzles 13 via an inlet coupling 88

In use, the manifold 10 1 is connected to a supply conduit similar to that shown in Figure 3 in which the pressure is regulated and measured, and in which the flow rate is also measured The nozzles 13 face downwardly into the clay or gravel When the nozzles 13 are located in the clay the measured pressure increases and the measured flow rate decreases When the manifold 10 1 is located in the gravel the measured pressure decreases and the measured flow rate increases Thus it can be determined if the nozzles 13 are located in clay or gravel The cutting blade 22 can thus be lowered through the gravel onto the clay by monitoring the measured pressure and flow rate in the supply conduit

Although not shown two spaced manifolds 10 1 may be located one above the other so that the nozzles of one of the manifolds can in use be located in the gravel and the nozzles of the other manifold in the clay thereby to optimise the position of the cutting blade 22

It will be appreciated that many modifications or variations of the invention are possible without departing from the spirit or scope of the invention

Claims

1 A device for determining a position in two layers of different permeability including at least one fluid outlet, means for supplying fluid to the outlet, measuring means for measuring the flow rate and/or pressure of the fluid to determine a position in the two layers

2 The device of claim 1 including a plurality of outlets spaced one above the other

3 The device of claim 2 wherein the spaced outlets increase in discharge capacity from an uppermost outlet to a lowermost outlet

4 The device of claim 3 wherein the spaced outlets comprise an increasing number of nozzles from the uppermost outlet to the lowermost outlet

5 The device of any of the above claims wherein the fluid is supplied to the outlet or outlets from a supply conduit

6 The device of claim 5 including pressure regulating means for regulating the pressure in the supply conduit

7 The device of claim 5 or claim 6 including fluid flow rate measuring means located in the supply conduit

8 The device of any of claims 5 to 7 including pressure measuring means for measuring the pressure in the supply conduit

9 The device of any of the above claims associated with material removing means of a mining machine so that the depth of the material removing means can be set relative to the two layers in response to a position determined by the device

The device of claim 9 wherein the outlet or outlets face downwardly relative to the direction of travel of the mining machine

The device of claim 10 wherein the outlet or outlets face sideways relative to the direction of travel of the mining machine

A mining machine including material removing means with a device as claimed in claim 1 associated with the material removing means so that the depth of the material removing means can be set relative to the two layers in response to a position determined by the device

A mining machine including material removing means for removing material in an upper layer located on a lower layer having a different permeability to the upper layer, the material removing means having a housing secured thereto, the housing having at least one fluid outlet through which fluid can be discharged, fluid being supplied to the fluid outlet via a conduit having measuring means for measuring the flow rate and/or pressure of the fluid in the conduit in order to determine in which of the two layers the outlet is located so that the depth of the material removing means can be set relative to the two layers

A method of determining a position in two layers having different permeabilities including the steps of supplying fluid to at least one outlet located in the layers, measuring the flow rate and/or pressure of the fluid and determining a position in the two layers from the measured flow rate and/or pressure

15. The method of claim 14 including the step of discharging fluid from the outlet downwardly onto the layers.

16. The method of claim 14 including the step of discharging fluid from the outlet substantially parallel to the layers.

17. The method of claim 14 including the step of supplying fluid to a plurality of spaced outlets located one above the other.

18. The method of any of claims 14 to 17 including the step of determining the position of an interface between the two layers from the measured flow rate and/or pressure.

19. The method of any of claims 14 to 17 including the step of determining the position of one layer relative to the other layer from the measured flow rate and/or pressure.

20. A method of controlling the depth of material removing means of a mining machine including the step of setting the depth of the material removing means in response to a position determined according to the method claimed in claim 14.

21. A method of controlling the depth of material removing means of a mining machine for removing material in an upper layer located on a lower layer having a different permeability to the upper layer, including the steps of locating at least one fluid outlet in the material, supplying fluid to the outlet, measuring the flow rate and/or pressure of the fluid, and determining in which of the layers the fluid outlet is located so that the depth of the material removing means can be set relative to the two layers.