Note: Descriptions are shown in the official language in which they were submitted.
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
M ETHODS, SYSTEVI SAND DEVICES FORM ONITORI NG MOVEM BAT OF ROCK IN AMINE
REID OF THE INVENTION
The present invention relates to the mining arts. In particular, the invention
relates to
methods for monitoring the movement of rock in a mine.
BACKGROUND TO THE INVENTION
In a mine, there is typically a volume of material having a higher
concentration (ore grade)
of the desired mineral, than the surrounding material. The material with
higher grade
mineral is generally termed the "ore body", and the material around the ore
body is
generally termed "host material".
Underground mining operations are designed to extract as much of the ore body,
and as
little as possible of the host material. One of the effects of inefficient
mining is dilution,
whereby the mixing of host material together with ore from the ore body
reduces the
overall ore grade.
Dilution has a significant detrimental effect on the economics of a mining
operation. If the
mining operation extracts and proceoscs a tonne of host material the costs
involved are the
same as for targeted ore, however the mine does not receive the revenue that
would have
been in extracted material. Therefore profits are reduced by the value of the
ore that was
expected, but not received. While underground cave-type mines (ablevel Caves
and Block
Caves) typically involve a low cost per tonne of material extracted; they
suffer from high
rates of dilution.
In the mining arts problems of dilution have been investigated and addre...,cd
by the use of
various marker devices. The markers are typically used to measure ore flow in
mass mines.
These flow measurements are often performed with metallic markers having
identification
codes inscribed thereon. Being metallic, these markers may be conveniently
retrieved by
magnetic separation means already existing in the mining process.
1
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
More recently, radio frequency identification (F1F1D) technologies have been
used to
uniquely identify markers. aich markers may be read by one or more detector
devices
disposed about the mine.
Typically, ore movement measurements commence with the installation of a
series of
markers into various positions of the mine, or into mined material. The
identification codes
and installation locations are recorded. At one or more points in the
extraction process, the
markers are retrieved (or read in the case of RF1D markers) and the codes
recorded along
with other data such as time of retrieval.
The installation position and retrieval details of a set of markers provide
valuable ore flow
information to mine management. By knowing the original installation position
of each
marker, along with the time and location of extraction, the movement of rock
in an
underground ore body can be analysed, revealing flow over time.
The measurement of ore movement is often required in open-pit mining. With
open pit
mining, the miner has the opportunity to choose where to send extracted
material.
Material believed to be ore is sent to the mill; whereas material believed to
be waste is sent
to a waste heap. The ore is usually sampled before blasting, and the boundary
between
targeted ore and waste is mapped. However, the process of blasting moves the
material,
and the ore-to-waste boundary moves. It is desirable for mining management to
measurement ore movement, to reduce lost ore and the processing of ore diluted
by waste.
Ore movement measurements are labour intensive because mine staff must
manually
recover the markers. Prior art techniques also lack precision and resolution.
A problem with these techniques using markers is that the collection of data
occurs at the
time the ore is extracted. -Ellis can lead to misinformation, or information
that is provided
when it is too late to make any adjustments to the mining process.
Measurement of rock movements is required in other contexts, such as in
underground
cave-type mines. It is often important to measure the upward propagation of
the cave as it
2
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
develops. As ore is being extracted from deep under the ground, the material
above the
65 extraction needs to "cave" and fall in to replace the extracted
material. With "block cave"
mining, the cave gradually propagates upwards to the surface, and eventually a
crater forms
on the surface. If, for whatever reason, the cave stops propagating, a cavity
will form
between the ore that has broken and fallen and the ore that is still in place.
If the mining
operation continues, this cavity will gradually grow in size as material is
extracted from
70 below. Eventually, the ceiling of this cavity will collapse. If the
cavity was large before the
collapse, an "air rush" can occur, because the highly pressurised air must
escape through
some means. If the air finds its way into a mine drive, it can have fatal
consequences. The
effect is similar to a blast. It is therefore important to measure the cave's
propagation.
75 Current technology to measure cave propagation involves "time domain
reflectometry"
(TDFI). Typically, holes are drilled from either the surface or from a tunnel
through the ore
body. These holes are populated with cables and associated electronic
equipment, and a
signal is transmitted along the cables. The signal reflects off the terminus
of the cable, with
the length of time taken for the signal to travel from the source to the
terminus of the cable
80 and back to a detector is measured. As the cave propagates, the end of
the cable breaks off
and therefore becomes shorter, thereby resulting in a shorter reflection time.
A common
problem with this approach is seen where the ground above the cave-front
splits and, the
two parts move relative to each other. This movement often cuts the cable at
points higher
than the cave front, resulting in incorrect data being provided.
It is an aspect of the present invention to overcome a problem of the prior
art by providing
improved methods, systems and markers for use in mining. It is a further
aspect of the
present invention to provide an alternative to the methods, systems and
markers of the
prior art.
The discussion of documents, acts, materials, devices, artides and the like is
induded in this
spedfication solely for the purpose of providing a context for the present
invention. It is not
suggested or represented that any or all of these matters formed part of the
prior art base
or were common general knowledge in the field relevant to the present
invention as it
existed before the priority date of each daim of this application.
3
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
SUM M ARY OF THE INVENTION
Throughout the description and the claims of this spedfication the word
"comprise" and
variations of the word, such as "comprising" and "comprises" is not intended
to exdude
100 other additives, components, integers or steps.
Fbference throughout this spedfication to "one embodiment" or "an embodiment"
means
that a particular feature, structure or characteristic described in connection
with the
embodiment is included in at least one embodiment of the present invention.
Thus,
appearances of the phrases "in one embodiment" in various places throughout
this
105 specification are not nececnnrily all referring to the same embodiment,
but may.
Furthermore, the particular features, structures or characteristics may be
combined in any
suitable manner, as would be apparent to one of ordinary skill in the art from
this
disclosure, in one or more embodiments.
110 In a first aspect, the present invention provides a method for
monitoring the movement of a
first rock region in a mine relative to a second rock region in the mine, the
method
comprising the steps of:
providing a first marker device and a second marker device,
the first marker device adapted to emit an electromagnetic signal,
115 the second marker device adapted to (i) detect the strength of
the
electromagnetic signal emitted by the first marker device, and (ii) wirelessly
transmit information related to the detected electromagnetic signal directly
or indirectly to a reader device,
installing the first marker device in the first rock region,
120 installing the second marker device in the second rock region, and
monitoring the information on the detected electromagnetic signal on the
reader
device,
wherein, in use, movement of the first rock region relative to the second rock
region is
indicated where the second marker device detects a decrease in the strength of
the
125 electromagnetic signal emitted by the first marker device.
4
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
In another aspect, there is provided a method for identifying a distance
between a first rock
region in a mine and a second rock region in the mine, or the relative
position of a first rock
region in a mine to a second rock region in the mine, the method comprising
the steps of:
130
providing a first marker device and a second marker device,
the first marker device adapted to emit an electromagnetic signal,
the second marker device adapted to (i) detect the strength or direction of
the electromagnetic signal emitted by the first marker device, and (ii)
135 wirelessly transmit information related to the detected
electromagnetic
signal directly or indirectly to a reader device,
installing the first marker device in the first rock region,
installing the second marker device in the second rock region, and
monitoring the information on the detected electromagnetic signal on the
reader
140 device,
wherein, in use, the distance between the first rock region and the second
rock region, or
the relative position of the first rock region to the second rock region, is
determined by
reference to the electromagnetic signal strength or direction emitted by the
first marker
device as detected by the second marker device.
145
The present invention provides one or more advantages over methods, systems
and devices
of the prior art. In particular, some embodiments of the method provide for
accurate (or at
least more accurate) real time information on ore position and/or flow in a
mining setting.
150 To further explain the operation of the method, the electromagnetic
signal emitted by the
first marker device radiates toward the second marker device which is adapted
to receive
the signal. Any increase or decrease in the level of the signal, or the simple
disappearance
of the signal, or a change in direction of the signal indicates that the two
markers have
moved relative to each other. It may therefore be reasonably inferred that the
regions of
155 rock surrounding the two marker devices have moved relative to each other.
This
information may be informative about the location and/or the changes in
location of the
two markers with respect to each other.
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
The skilled person understands that absolute distance (or an approximation
thereof)
160 between two marker devices may be determined by reference to the
electromagnetic signal
strength. It is commonly known that signal strength decreasPs with distance
according to
the relationship d...-1/r3
Where a non-isotropic antenna is used in the marker devices, a change in
signal strength
165 may only indicate relative movement between two markers. However, where
antennae
which are doser to isotropic are used, the signal strength may be
determinative of relative
position.
Knowledge of the distances between marker devices, and the relative positions
of each
170 marker device in relation to others may allow the construction of
detailed three-
dimensional maps of the markers. When this information is also provided in
real time (as
provided by the present invention) mining operations can be significantly
improved.
As used herein, the term "rock region" includes an area of rock surrounding
the marker
175 device. The term is intended to indude solid rock, in which case the
marker device is
typically installed via a pre-drilled downhole. The term also indudes
fragmented rock of the
type produced by a mining process (such as blasting) in which rasp the marker
is placed
onto or into a pile of fragmented rock.
180 Considering an application of the present methods in measuring the
propagation of a cave
front in a cave-type mine, the first marker device is installed within a rock
region which is
deep, and proximal to the advandng cave front, while the second marker device
is installed
in a rock region which is more shallow, and distal to the advancing cave
front. Before any
mining activity, the electromagnetic signal emitted by the first marker device
is received by
185 the second marker device. The inference is that the two markers have
not been physically
separated, and so the cave front is inferred to be deeper than the first
marker.
When rock surrounding the first marker device is removed by the caving process
in a block
cave (for example), that region of rock drops toward the floor of the mine.
The now greater
190 distance between the first and second marker devices causes a decrease
in the level of the
6
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
electromagnetic signal received by the second marker device. This decrease in
signal
indicates that the blasted rock has (as is desired) fallen to the mine floor.
Where no
decrease in signal is observed after caving, this indicates that the cave
front has not yet
propagated to the rock surrounding the first marker, or that it has propagated
but that the
195 material has not fallen to the mine floor.
It will be appreciated that where a plurality of substantially vertically
disposed markers are
used, and the depth of each marker is known, it will be possible to infer the
position of the
cave front. For example, where marker devices are installed at sequential
depths of 100,
200 105, 110, 115, and 120 meters before any mining begins all markers will
receive an
electromagnetic signal from a neighbouring marker (typically the marker
disposed below) at
a strength arbitrarily defined as 100% Once blasting begins, the marker at the
120 meter
level is the first to fall away while the marker at the 115 meter level
remains lodged in the
rock above. The marker at the 115 meter level detects that the strength of the
205 electromagnetic signal emitted by the marker at the 120 meter level has
decreased to 5%
and transmits that information to the reader device.
Information on the decrease in signal strength (as detected by the second
marker) is
transmitted by the second marker via wireless means to a reader device. The
reader device
210 may be an electronic device adapted to interpret the information from
the second marker
device, or may simply relay the information to another electronic device (such
as a
computer) for interpretation. Alternatively, the reader device may be a
computer capable
of receiving and interpreting the information. The reader device indude means
for
receiving the wireless signal from one or more marker devices (either directly
or indirectly),
215 such as an antenna The reader's antenna may be of the same type as that
of the markers,
but may also have a different form factor.
As discu,,,,cd in the embodiment supra, the present invention may comprise the
use of
multiple marker devices. Accordingly, in another aspect the present invention
provides a
220 method for monitoring the movement of a first rock region in a mine
relative to a second
rock region in the mine, the method comprising the steps of:
7
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
providing a plurality of marker devices, with most or all of the marker
devices
adapted to (i) emit an electromagnetic signal and (ii) detect the strength of
the
electromagnetic signal emitted by a neighbouring marker device, and (iii)
wirelessly
225
transmit information related to the detected electromagnetic signal directly
or
indirectly to a reader device,
installing the marker devices in separate regions of rock, and
monitoring the information on the detected electromagnetic signal on the
reader
device,
230 wherein, in use, movement of one of the plurality of marker devices
relative to a
neighbouring marker device is indicated where the neighbouring marker device
detects a
decreasP in the strength of the electromagnetic signal emitted by the one
marker device.
In another embodiment there is provided a method for identifying a distance
between a
235 first rock region in a mine and a second rock region in the mine,
or the relative position of a
first rock region in a mine to a second rock region in the mine, the method
comprising the
steps of:
providing a plurality of marker devices, with most or all of the marker
devices
adapted to (i) emit an electromagnetic signal and (ii) detect the strength or
direction
240 of
the electromagnetic signal emitted by a neighbouring marker device, and (iii)
wirelessly transmit information related to the detected electromagnetic signal
directly or indirectly to a reader device,
installing the marker devices in separate regions of rock, and
monitoring the information on the detected electromagnetic signal on the
reader
245 device,
wherein, in use, the distance between the first rock region and the second
rock region, or
the relative position of the first rock region to the second rock region, is
determined by
reference to the electromagnetic signal strength or direction emitted by one
of the plurality
of marker devices as detected by a neighbouring marker device.
250
As mentioned in the Background section herein, in an underground mining
operation the
challenge is to understand and measure material flow and its effects on the
cave.
Measuring ore flow requires a reasonably high number of data points. Having
more data
8
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
points increases the resolution of data, which makes the data more useful.
This is because
255 material flow tends to be quite localised. Fbcks tend to hang and other
rocks tend to flow
past them.
The use of a plurality of marker devices leads to a problem in some
applications.
qpecifically, the distance between a marker and the reader device (or at least
receiving
260 antenna of the reader device) may become too great for reliable
transmission of the
information. Applicant proposes that this problem may be overcome or
ameliorated by the
implementation of the marker devices as means for relaying the information.
aich
networks are often referred to as a "mesh network". As is understood by the
skilled person
mesh networking is a type of networking where each node must not only capture
and
265 dimominate its own data, but also serve as a relay for other nodes,
that is, it must
collaborate to propagate the data in the network. In the context of the
present invention,
each marker device disseminates electromagnetic signal strength information,
and also acts
as a node itself to relay signal strength information dissominated by other
markers, the
network being configured to carry signal strength information to the reader
device.
270
A mesh network can be designed using a flooding technique or a routing
technique. When
using a routing technique, the message propagates along a path, by hopping
from node to
node until the destination is reached. To ensure all its paths' availability,
a routing network
must allow for continuous connections and reconfiguration around broken or
blocked paths,
275 using self-healing algorithms. A mesh network whose nodes are all
connected to each other
is a fully connected network. Mesh networks can be seen as one type of ad hoc
network.
The self-healing capability enables a routing based network to operate when
one node
breaks down or a connection goes bad. As a result, the network is typically
reliable, as there
280 is often more than one path between a source and a destination in the
network.
Accordingly, in one embodiment of the method the marker device(s) (the first
marker
device, the second marker device, or any one or all of the plurality of marker
devices) is
adapted to relay information related to the detected electromagnetic signal.
aated another
285 way the marker devices are adapted to transmit the information by a mesh
networking
9
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
protocol. In this embodiment, the marker devices form a network, whereby the
information
related to the detected electromagnetic signal is passed from one marker
device to another
marker device, to yet another marker device and so on, before arriving at the
reader device.
Thus, a single marker device has the three functions of emitting an
electromagnetic signal,
290 detecting an electromagnetic signal and relaying information related to
an electromagnetic
signal detected by another marker device.
In one embodiment, where the information related to the detected
electromagnetic signal
is transmitted indirectly to the reader device, the transmission is via a
neighbouring marker
295 device. In certain embodiments, the transmission of information is via
2, 3, 4 or a plurality
of neighbouring marker devices. The number of marker devices via which the
information
transmitted to the reader device may be equal to or greater than about 2, 3,
4, 5, 6, 7, 8, 9,
10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 30, 40 or 50 marker devices.
300 The mesh network-based embodiments of the present methods provide
significant
advantages One advantage is that the monitoring of relative rock movements
over
extended distances is possible. The underground transmission of radio
frequency signals,
for example, is significantly hampered by solid rock. The ability to relay
information from
one marker device to another provides the ability to monitor rock movements in
a very
305 deep body of ore. In some embodiments, the depth of the ore body capable
of being
monitored by the present methods is greater than or equal to about 100, 200,
300, 400,
500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800,
1900, 2000,
2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900 or 3000 meters
310 The electromagnetic signal may be simple electromagnetic energy, or it
may encode data
and/or information. alitable types of electromagnetic signal include those
operable across
a required distance, and through the one or more media that would be
encountered in use
(such as solid rock and/or fragmented rock). In one embodiment, the
electromagnetic
signal has a frequency lower than that of microwave radiation.
315
In one embodiment the electromagnetic signal is a radio wave signal. The use
of radio
waves in a simple signal is all that is required for the purposes of
determining whether one
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
marker device has moved relative to another. It is not required that the radio
wave signal
encodes any information.
320 In another embodiment the wireless transmission is by radio wave, this
type of transmission
being capable of encoding information, and therefore more complex than a
simple signal.
In yet a further embodiment the electromagnetic signal and the wireless
transmission are
both radio waves.
The use of radio waves as the electromagnetic signal is advantageous because
it also allows
325 for radio frequency (RF) transmission of information between markers.
Thus, in this
embodiment, the emission of RF from a marker device acts as both (i) the
electromagnetic
signal (the strength of which is used as an indicator of distance between
markers), and (ii)
means for wirelessly transmitting information between markers.
330 By implementing antennas that are either isotropic (i.e. radiate at the
same signal strength
in each direction), or multi-axis (3 identical antennas at orthogonal angles),
the PF signal
strengths can be used to measure distance. Each set of PF signal strengths
allows the
relative distance of each pair of markers to be calculated. When this
information is
collected for many pairs of markers, and for the Fader-Marker pairs, the real-
time position
335 of all markers can be calculated.
The absolute positioning error of markers will increase as more hops are
required from the
reader device to the marker whose position is being determined. However, this
error can be
reduced with multiple communication paths, or if the network spans from one
(set of)
340 reader devices (which are in known positions) to another (set of)
reader devices in another
area of the mine.
Note that the system is useful even if accurate positioning cannot be
measured. For
example, if the markers have non-isotropic antennas (i.e. the field strength
varies in
345 different directions), it will still be possible to have communications
hop from marker to
marker. It will also still be possible to detect movement of markers, because
the signal
11
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
strength between markers will change ¨ even though the exact change may not be
accurately measured.
350 The selection of frequency may be by consideration of the following
factors. Through-the-
ground PF communications need be of low enough frequency to penetrate the
ground with
low attenuation. However, in order to achieve a reasonable data rate (in order
to transfer
reasonable amounts of data without overly expending energy in the marker
device battery),
the frequency should not be too low. Thus, a compromise in choice of frequency
is
355 presented: a low frequency penetrates better through rock but has low
data rates and large
antenna needs, whereas a high frequency has poor penetration through rock but
higher
data rates.
In one embodiment, the frequency is selected from the range of about 1 Hz to
about 1 GHz.
360 In another embodiment the frequency is selected from the range of about
10 Hz to about
100 MHz. In yet a further embodiment the frequency is selected from the range
of about 10
Hz to about 30 MHz. Preferred frequencies are 13.56 MHz and 125 to 134.2 kHz
(often
referred in the art to "128 kHz")
365 In one embodiment, the information is transmitted by a mesh networking
protocol. An
advantage of the present invention is the ability to measure and communicate
(through the
chain of markers in a mesh network) the FF field strengths between markers.
This
information informs a user of the system about the location and the changes in
location of
markers with respect to each other.
370
The skilled person is familiar with a range of protocols induding for routing
packets across
mesh networks, induding, examples including AODV (Ad hoc On-Demand Distance
Vector),
B.A.T.M.AN. (Batter Approach To Mobile Adhoc Networking), Babel (protocol) (a
distance-
vector routing protocol for IPv6 and IPv4 with fast convergence properties),
DNVR (Dynamic
375 Nlx-Vector Fbuting), DEA/ (Destination-&quenced Distance-Vector
Routing), DS R (Dynamic
asurce Fbuting), HaS (Hazy-Sghted Link Sate), HWMP (Hybrid Wireless Mesh
Rotocol),
IWMP (Infrastructure Wireless Mesh Rotocol) for Infrastructure Mesh Networks
by GPM
12
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
M RP (Wireless mesh networks routing protocol) by Jangeun Jun and Mihail L
Schitiu, OLSR (Optimized Link Sate Flouting protocol), OOPP (OrderOne Pouting
Protocol)
380 (OrderOne Networks Pouting FYotocol), OSRF (Open Siortest Path Rrst
Fbuting), PVVRP
(Predictive Wireless Fbuting Protocol), TORA (Temporally-Ordered Fbuting
Algorithm), and
IEEET802.15.4 (ZgBee) IEEE 802.15.4. Such protocols may be used as a basis for
a protocol
workable within the context of the present methods, with the skilled person
being enabled
to do so. For completeness only, the following suggested protocol parameters
are provided.
385 In the protocol, the data packet may comprise one or more the following
items of
information:
a Preamble,
b. Rags to define the type of data packet,
c. A variable to influence the number of markers that are skipped when
rippling
390 communications along each Sulonet,
d. Sze of data packet,
e. Crigin address: athnet and Marker,
f. Destination address: Subnet and Marker,
g. Node Route from Origin address to Destination (see below for more
395 information),
h. Payload,
0/di c Fbdundancy Check (CR3) of data packet,
j. Footer
400 The Node Fbute may contain the following information for each transition
between
neighbouring subnets that the packet requires to pass through to get from the
originating
subnet to the destination subnet:
= Direction of communications along first atnet (ie upstream or downstream
405 along the subnet),
= Linking Node in first Sulonet (Sulonet and Marker), and
= Linking Node in second ailonet (ailonet and Marker).
13
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
If the communications need to pass from subnet to subnet N times in order to
get to the
410 destination subnet, the Node Fbute will contain N sets of the above
information.
Typically, all communications are commenced and controlled by the reader
device. The
system includes the following commands, amongst others:
415 1. Fing (within a particular subnet, find out which is the
furthest marker that
can be contacted);
2. Neighbour discovery; and
3. aibnet Hibernate.
420 In some embodiments, the protocol is adapted to take account of issues
specific to mining
applications. For example, to preserve battery power in marker devices, the
protocol may
specify that packets do not necessarily pass through each and every marker
along a subnet.
The markers will generally be placed at intervals less than half the range of
communication
between two markers to ensure that failure of individual markers do not cause
loss of a
425 subnet. -Ellis also means that communications along a subnet can skip
markers and
therefore preserve the batteries in the skipped markers. The protocol may
include a
parameter that tells the marker whether to skip markers when relaying the
packet of data,
and how many markers to skip. This can be implemented in different ways: for
example, a
marker trying to relay a packet could request a short response from all
markers in range,
430 and choose to forward the message to (for example) the marker with the
second (or third)
strongest FFsignaJ in the required direction along the subnet.
In one embodiment of the method, each of the plurality of marker devices is
uniquely
identifiable, with an identification code being included in a data packet. In
addition, the
435 method may further comprise the step of recording the installation
position of each
uniquely identifiable marker device. In this way, it is possible to construct
a map of the
relative positions of the marker devices, and derive important information on
rock
movements in the mine.
14
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
440 In a further aspect the present invention provides a marker comprising
(i) means for
emitting an electromagnetic signal, (ii) means for detecting the strength or
direction of an
electromagnetic signal emitted by a neighbouring marker device, and (ii) means
for
wirelessly transmitting information related to the detected electromagnetic
signal to a
neighbouring marker device.
445
Gven that the present markers are used under challenging conditions, certain
embodiments
of the marker comprise a marker housing adapted to physically protect the
electronics
contained therein from a mining activity. As used herein, the term "mining
activity" is
intended to indude any activity capable of causing temporary or permanent
damage to the
450 electronics of the marker. Fblevant mining activities indude blasting,
drilling, hammering,
digging, and the like. In one embodiment, the housing is adapted to physically
protect the
electronics from blasting, and in certain embodiments the st ress waves
associated with that
activity.
455 In one embodiment, the housing is adapted to pass radio waves with
minimal attenuation.
As will be appreciated by the skilled artisan, a balance may exist between the
level of
protection provided by a housing, and the (negative effect) of signal
attenuation. The
housing may attenuate the waves by less than about 90, 80, 70, 60, 50, 40, 30,
20, or 10%,
however a housing having an attenuation of less than about 50%is preferred.
460
In one embodiment, the marker comprises a marker housing including at least
two
bordering material layers surrounding at least part of PF electronics housed
within the
marker housing, wherein there is a change in properties between adjacent
layers so that
shock waves are deflected around the PF electronics.
465
In another embodiment, the marker device comprises a housing induding at least
two
bordering material layers surrounding at least part of FF electronics housed
within the
marker housing, wherein there is an impedance mismatch between any adjacent
two of the
at least two material layers.
470
In one embodiment, the marker housing has a casing of impact resistant
plastics material.
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
In one embodiment, the casing is of modified polyphenylene ether resin. In
particular the
casing may be of modified polyphenylene oxide and polyphenylene ether resin.
More
specifically, the rasing may be a blend of polyphenylene oxide and
polystyrene.
475
In another embodiment, the marker device comprises a marker housing
comprising: a
casing; and a core within which at least part of FF electronics is housed, the
core being
suspended within the casing. In one embodiment the at least part of RF
electronics
comprises a printed circuit board including electronic components.
480
In one embodiment, the core includes a resiliently deformable tube forming the
outside of
the core and the printed circuit board is housed within a bore of the tube.
In one embodiment, the space between the casing and the tube is filled with a
first
485 strengthening material having material properties which provide an
impedance mismatch at
the interface between the first strengthening material and one or both of the
casing and the
tube. By "impedance mismatch" it is meant a discontinuity in the mechanical
and/or
acoustic properties of adjacent materials to encourage a shock wave to pass
around the
interface instead of through it, and to inhibit cracks from propagating across
the interface.
490
In one embodiment, the first strengthening material is a composite. More
specifically the
composite is a fibre-reinforced plastic and particularly a polymer matrix
reinforced with
fibreglass. In one embodiment, the core includes a second strengthening
material which is
located within the bore of the tube and abuts the inside of the tube.
495
In one embodiment, the second strengthening material is a composite. More
specifically the
composite is a fibre-reinforced plastic and particularly a polymer matrix
reinforced with
fibreglass.
500 In one embodiment, the core further indudes a shock absorbing material
attached to the
printed circuit board. The shock absorbing material may be foam material.
16
In one embodiment the tube is of plastics material. In particular the tube may
be of
polyvinyl chloride material.
505
With further regard to suitable housings, reference is made to Applicant's
international
patent application published as WO/2011/035378 Al.
510 In another aspect the present invention provides a system comprising a
plurality of marker
devices wherein most or all of the marker devices are adapted to (i) emit an
electromagnetic signal and (ii) detect the strength or direction of the
electromagnetic signal
emitted by a neighbouring marker device, and (iii) wirelessly transmit
information related to
the detected electromagnetic signal directly or indirectly to a reader device.
In one
515 embodiment, the system further comprises a reader device.
In one embodiment of the system most or all of the marker devices are adapted
to transmit
the information by a wireless mesh networking protocol.
In another embodiment the electromagnetic signal is a radio wave signal. In
one
embodiment the wireless transmission is by radio wave signal. In one
embodiment the
520 electromagnetic signal and the wireless transmission are both radio
waves.
In one embodiment the radio wave has a frequency of between about 10 Hz to
about 30
MHz.
In one embodiment of the system any one of the plurality of marker devices
comprises a
housing adapted to physically protect the electronics contained therein from a
mining
525 activity. In another embodiment the housing is adapted to pass radio
waves.
In one embodiment the system is operable or is operated in a cave-type mine.
While the above predominantly describes applications for underground mining,
the present
invention also has applications in other types of mining. With open-pit
mining, the miner
530 has the opportunity to choose where to send extracted material.
Material believed to be
ore is sent to the mill; whereas material believed to be waste is sent to a
waste heap. The
ore is usually sampled before blasting, and the boundary between targeted ore
and waste is
17
CA 2875684 2019-05-02
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
mapped. However, the process of blasting moves the material, and the ore-to-
waste
boundary moves. The invention can be utilized to allow measurement of ore
movement, to
535 reduce lost ore and the processing of ore diluted by waste.
The present invention will now be more fully described by reference to the
following non-
limiting embodiment.
540 DETAILED DEMI:MON OF A PREFERRED BA BODIM ENT OF THE INVENTION.
Fbference is made to Hg 1 which shows in diagrammatic cross section a cave-
type of
underground mine. A series of holes are drilled into the ore body, into which
markers are
installed at regular depths. Each marker is able to send and receive
information by FF.
545 Each marker is allocated a two-part identifying code, consisting of a
"subnet" and a " Marker
ID". The subnet is associated with the hole into which the string of markers
is inserted. The
Marker ID is a sequential number, such that the markers along the hole have
gradually
increasing Marker IDs. All communications are initiated from a reader device
that is
accessible and serviceable by mine staff. The reader device is capable of
communicating
550 with a certain number of markerswithin range.
In Hg 1, a series of 4 vertically oriented drillholes is shown, with each
having 12 marker
devices disposed at regular intervals: marker 01 is the deepest, while marker
12 the most
shallow.
555
Each set of 12 markers in a single downhole defines a subnet. Thus, subnet 10
comprises
markersl to 12. abnet 20 comprises a second group of markers 1, 2, 3...12, and
so on.
Rgure 1 also shows 3 horizontally disposed ailonets (01, 02 and 03), with each
allonet
560 having a number of PF detectors (01, 02, 03 ... ). Each aibnet 01, 02
and 03 relays
information to a reader device (reader 01, reader 02, and reader 03) via node
99.
18
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
When ore is fragmented from the mine, the cave front propagates upwardly. In
the process
of fragmentation, the markers drop downwardly into the cave sequentially
(marker 01 first,
565 and marker 12 last).
As an example of atypical set of communications, the method of identifying the
best nodes
to link allonet 03 to adonet 20 is now presented.
570 To identify the best nodes to link to other albnets, the system
performs a "Neighbour
Discovery" command on each marker in abnet 03. A Neighbour Discovery command
is
focussed on the signal strengths between a specifically-addressed marker and
all other
markers within range of that marker. With the example scenario, the Neighbour
Discovery
command will therefore be repeated for each marker in abnet 03. This data is
collected
575 and stored (in the Fader or in the computing equipment connected to the
Reader) in order
to decide on the routing for future communications.
The markers in range (as detected by a Neighbour Discovery command) could be
in the
same subset or in other subnets.
580
In order to communicate with another subnet, the system chooses a marker
having strong
communications with the other subnet. Take the example of the figure below.
appose we
want to communicate with markers in aibnet 20, from abnet 03. appose that &met
03
markers 12, 11, 10 and 09 are all within range of markers from athnet 20. Oven
their
585 relative distances, suppose that Marker 11 has the strongest signal,
when communicating
with athnet 20, Marker 12. Therefore, in future communications from athnet 03
to 20, the
routing information would be as follows:
Origin: abnet 03, Marker 99
590 Node Route
Direction: Downstream
Link from: athnet 03, Marker 11
Link to: atnet 20, Marker 12
19
CA 02875684 2014-12-04
WO 2013/181720 PCT/AU2013/000629
595 With this routing information, a Neighbour Discovery command can be issued
to each
marker in abnet 20, via abnet 03. This will provide the FF signal strength
between for
each pair of intercommunicating markers.
The figure below shows a scenario whereby the system is used to measure the
position of
600 the cave front. abnets 01, 02 and 03 are along a tunnel through the
ore. From this tunnel,
various holes are drilled into the ore (abnets 10, 20, 30 and 40). Eventually,
as material is
extracted from the bottom of the mine, the whole area will gradually collapse
and sink
down. Therefore, the tunnel will become unsafe for humans. That is why readers
cannot be
placed at the start of subnets 10, 20, 30 and 40. Communications to these
subnets need to
605 be made via abnets 01, 02 and 03.
The three subnets (01, 02 and 03) in the main tunnel are redundant for the
following
reasons:
610 (i) To save battery power. Two aibnets can be put to Hibernate, using
the Hibernate
command. The Hibernate command makes the commanded subnet Hibernate for the
period of time spedfied in the Hibernate command (say, 1 week). For example,
aibnets 01
and 02 may be commanded to Hibernate, and abnet 03 would then be used to
communicate. This preserves the batteries in abnets 01 and 02. The load on the
batteries
615 can be managed by later communicating on, say, abnet 01, and putting
abnets 02 and 03
to Hibernate.
(ii) Reliability. If, overtime, markers fail (eg due to flat batteries), the
remaining subnets can
ensure that communications are still possible. Even if several markers have
failed in all
620 abnets, the routing algorithm can allow communications to switch from
atnet to ailonet
along its length.
By using a combination of Prig commands and Neighbour Discovery commands, we
can
regularly check on the mine's caving progress. As the mine caves, the lower
markers will
625 start to move away from the rest of the subnet. As they move, their PF
signal strength (as
measured by the Neighbour Discovery command) will change, and reduce.
Ping and Neighbour Discovery commands require a response from a particular
marker.
With a Rng command, the marker that must respond is t he one that could not
make contact
630 with any markers further along the subnet, in the required direction. That
marker
constructs a packet of information and sends it back to the reader, using the
same path as
the outgoing command. The communication technique and data packet structure is
the
same as for the command, but the route will be the opposite, and the type of
packet is
"Data" instead of a command.
635
It will be appredated that in the description of exemplary embodiments of the
invention,
various features of the invention may be -grouped together in a single
embodiment, figure,
or description thereof for the purpose of streamlining the disclosure and
aiding in the
understanding of one or more of the various inventive aspects. This method of
disdosure,
640 however, is not to be interpreted as reflecting an intention that the
daimed invention
requires more features than are expressly recited in each daim. Pather,
inventive aspects lie in less than all features of a single foregoing disdosed
embodiment.
645
Furthermore, while some embodiments described herein indude some but not other
features induded in other embodiments, combinations of features of different
embodiments are meant to be within the scope of the invention, and from
different
650 embodiments, as would be understood by those in the art. For example,
in the claims
appended to this description, any of the claimed embodiments may be used in
any
combination.
In the description provided herein, numerous specific details are set forth.
However, it is
655 understood that embodiments of the invention may be practiced without
these specific
details In other instances, well-known methods, structures and techniques have
not been
shown in detail in order not to obscure an understanding of this description.
21
CA 2875684 2019-05-02
