Note: Descriptions are shown in the official language in which they were submitted.
RAISE FORMING SYSTEM AND METHOD
FIELD OF THE INVENTION
[0001] The present invention is a method of forming a raise in a body of
rock.
BACKGROUND OF THE INVENTION
[0002] In the prior art, excavating raises in underground mining is one
of the more difficult
tasks in mine development. As is known in the art, in conventional mining
construction hoists
may be used to enable miners to have reasonably safe access to a workface in
the raise, for
drilling and blasting when the raise is being formed. Alternatively, raise
bore machines have
recently been developed that can excavate the raise by boring through the
ground.
[0003] However, the known methods of forming raises have disadvantages.
Workers on
a construction hoist may still be exposed to risks that are unacceptable,
depending on the
circumstances. Raise bore machines are extremely expensive, and significant
time is required
for set-up and also dismantling.
SUMMARY OF THE INVENTION
[0004] For the foregoing reasons, there is a need for a system and a
method that
overcomes or mitigates at least some of the defects and disadvantages of the
prior art.
[0005] In its broad aspect, the invention provides a method of forming a
raise defined by
a central axis in a body of rock, the raise being located between upper and
lower drifts. Two outer
holes are formed on the raise perimeter, on opposite sides of the raise
perimeter. A blasthole is
formed coaxial with the central axis. With wire saws located in the upper and
lower drifts, a wire
initially located in the outer holes cuts the rock to form respective slots on
the raise perimeter as
the wire saws are rotated in unison about the central axis. Each of the slots
defines a bridge at
an outer hole, the bridges connecting an internal portion of the rock that is
inside the raise
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perimeter with a host portion of the rock. The internal portion is removed by
blasts initiated in the
blasthole, starting at a lower end of the blasthole that is at the lower drift
roof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The invention will be better understood with reference to the
attached drawings, in
which:
[0007] Fig. 1 is a cross-section of a portion of a mine in which a raise
is to be formed in a
body of rock;
[0008] Fig. 2 is a cross-section of the portion of the mine of Fig. 1
showing two outer holes
and a blasthole located therebetween extending between an upper drift and a
lower drift;
[0009] Fig. 3A is a cross-section of the portion of the mine of Figs. 1
and 2 showing upper
and lower wire saws located in the upper and lower drifts respectively,
positioned for alignment
with outer holes;
[0010] Fig. 3B is a cross-section of the portion of the mine of Figs.
1,2, and 3A in which
the wire saws pull a wire through the outer holes, drawn at a smaller scale;
[0011] Fig. 3C is a cross-section of one of the outer holes and the wire
located therein,
drawn at a larger scale;
[0012] Fig. 3D is a top view of a part of the floor of the upper drift in
which the outline of
the raise is shown, with the two outer holes and the inner hole, drawn at a
smaller scale;
[0013] Fig. 3E is a top view of the part of the floor of the upper drift
showing cuts made
by the wire, to partially define an internal portion of the rock to be
removed;
[0014] Fig. 4 is a cross-section of the portion of the mine of Figs. 1,
2, 3A, and 3B in which
the wire saws have been removed in preparation for blasting, drawn at a
smaller scale; and
[0015] Fig. 5 is a cross-section of the portion of the mine of Figs. 1,
2, 3A, 3C, and 4 in
which the completed raise is shown.
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DETAILED DESCRIPTION
[0016] In the attached drawings, like reference numerals designate
corresponding
elements throughout. Reference is made to Figs. 1-5 to describe an embodiment
of a method of
forming a raise 22 in a body of rock 24 (Fig. 5) in accordance with the
invention.
[0017] As will be described, once formed, the raise 22 is defined by a
raise wall 25 (Fig.
5) that is at least partially parallel with a raise perimeter 26 (Fig. 3D)
that has a radius 28 thereof
centered on a central axis 30 of the raise 22 (Figs. 1, 3D). It will be
understood that the raise
perimeter 26 extends through the body of rock 24 between a floor 32 of an
upper drift 34 and a
roof 36 of a lower drift 38 (Fig. 1).
[0018] In one embodiment, the method includes, first, identifying
locations "A1", "A2" on
the floor 32 of respective upper ends 40, 42 of first and second outer holes
44, 46 to be formed
on the raise perimeter 26 at opposite sides of the raise perimeter 26 (Figs.
1, 2). As can be seen
in Fig. 3D, the outer holes 44, 46 preferably are coincident with the raise
perimeter 26.
Accordingly, the raise perimeter 26, as illustrated in Fig. 1, also indicates
the center lines of the
outer holes 44, 46.
[0019] A location "B" on the floor of an upper end 48 of a blasthole 50
is also identified, in
Fig. 1. The blasthole 50 is to be formed coaxial with the central axis 30 of
the raise 22. Those
skilled in the art would appreciate that identification of the locations "A1",
"A2", and "B" may be
achieved by using any suitable surveying method.
[0020] Next, the first and second outer holes 44, 46 and the blasthole 50
are formed.
Those skilled in the art would appreciate that the holes 44, 46, 50 may be
formed by any suitable
method, e.g., by drilling with a suitable drill "D" (Figs. 1, 2). As can be
seen in Fig. 2, once formed,
each of the first and second holes 44, 46 and the blasthole 50 preferably
extend between
respective upper ends 40, 42, 48 thereof at the floor 32 of the upper drift 34
and respective lower
ends 52, 54, 56 thereof at the roof 36 of the lower drift 38.
[0021] The outer holes 44, 46 and the blasthole 50 may have any suitable
diameters.
Those skilled in the art would be aware of suitable diameters, and also
suitable drills. For
example, the diameters may be between one inch and six inches.
[0022] Those skilled in the art would appreciate that the outer holes 44,
46 and the
blasthole 50 are formed in accordance with the raise perimeter 26, i.e., the
outer holes 44, 46 and
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the blasthole 50 are formed in accordance with the design of the raise 22 that
is to be formed. It
will be understood that the outer holes 44, 46 and the blasthole 50 are shown
in Figs. 2, 3A, 3B,
and 4 as being vertical for clarity of illustration. In practice, because the
raise may be designed
to be non-vertical, the outer holes and the blasthole may also be non-vertical
accordingly.
[0023] Once the holes 44, 46, 50 have been formed, an upper wire saw 58
having an
upper sheave 60 preferably is positioned in the upper drift 34, on the floor
32 of the upper drift 34
(Fig. 3A). As can be seen in Fig. 3A, it is also preferred that a lower wire
saw 62 having a lower
sheave 64 is positioned in the lower drift 38, on a floor 65 of the lower
drift 38. Each of the upper
and lower sheaves 60, 64 is rotatable about its own sheave rotation axis, to
pull a wire 66. The
rotation axis of each of the upper and lower sheaves 60, 64 is horizontal, or
substantially
horizontal. A rotation axis 67 of the upper sheave 60 is shown in Fig. 3D. It
will be understood
that the rotation axis of the lower sheave 64 is omitted from Fig. 3D for
clarity of illustration.
[0024] It will also be understood that the wire 66 forms an endless loop,
and that the upper
and lower wire saws 58, 62 are positioned to draw the wire 66 pulled over the
upper and lower
sheaves 60, 64 through the first and second outer holes 44, 46. For example,
in Fig. 3B, the wire
66 is moved generally upwardly (i.e., in the direction indicated by arrow "X"
in Fig. 3B) through
the second outer hole 46, and generally downwardly (i.e., in the direction
indicated by arrow "Y"
in Fig. 3B) through the first outer hole 44. The wire 66 is initially moved
through each of the outer
holes parallel to the outer hole, or substantially parallel to, the outer hole
in which it is located.
[0025] Those skilled in the art would appreciate that, alternatively, the
wire 66 may initially
be moved generally upwardly through the first outer hole 44, and generally
downwardly through
the second outer hole 46.
[0026] The wire may be any suitable wire or cable. Those skilled in the
art would be
aware of suitable wires or cables. For example, the wire may be a diamond wire
designed for
cutting rock. Those skilled in the art would appreciate that the wire or cable
diameter is
determined based on the length of the cut to be made, ground types and
conditions, and also the
time in which the cut is to be made. Depending on the conditions, custom
cables may be made.
[0027] As noted above, the outer holes 44, 46 and the blasthole 50 are
shown as being
vertical for clarity of illustration. It will be understood that, depending on
the orientation of the
outer holes 44, 46, the movement of the wire 66 through the outer holes 44, 46
may be vertical,
substantially vertical, or non- vertical.
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[0028] The upper and lower sheaves 60, 64 are positioned relative to the
outer holes 44,
46 so that the wire 66 is dragged against an internal wall 68 of each of the
holes 44, 46, at the
same time as the wire 66 is moved through the holes, parallel to the holes. As
will also be
described, due to friction, the wire 66 cuts the rock 24 as it is drawn
through the first and second
outer holes 44, 46 because the wire 66 is dragged against the internal wall 68
of each of the holes
44, 46 (Fig.3D).
[0029] While the wire 66 is drawn through the first and second outer
holes 44, 46, the
upper and lower sheaves 60, 64 preferably are rotated about the central axis
30 in unison. This
rotation causes the wire 66 to be urged in the direction indicated by arrow
"C" in Fig. 3C. It will
be understood that, in Fig. 3C, the wire 66 is shown in an outer hole when the
wire 66 is first
engaged with the internal wall 68 of the outer hole.
[0030] The upper and lower sheaves 60, 64 are rotated about their
respective rotation
axes to pull the wire 66 through the outer holes 44, 46 at the same time as
the upper and lower
sheaves 60, 64 are rotated about the central axis 30, to urge the wire against
the internal walls
68 of the outer holes 44, 46.
[0031] Accordingly, upon the rotation of the upper and lower sheaves 60,
64 about their
respective rotation axes, the wire 66 is pulled through the outer holes, and
upon rotation of the
upper and lower sheaves 60, 64 about the central axis 30, the wire 66 is also
dragged against the
internal walls 68 of each of the outer holes 44, 46, causing the wire to cut
through the rock 24
along the raise perimeter 26. As can be seen in Fig. 3B, due to the rotation
of the sheaves 60,
64 about the central axis 30, the wire 66 in the outer hole 44 is urged in the
direction indicated by
arrow "C1", and the wire 66 in the outer hole 46 is urged in the direction
"C211
.
[0032] As can be seen in Fig. 3E, the wire 66 cuts through the rock 24 to
partially form
the raise wall 25 that is at least partially parallel with the raise perimeter
26. It is preferred that
the wire 66 cuts the rock along the raise perimeter 26. Preferably, the wire
66 forms a first slot
70 extending from the first outer hole 44 to a first bridge 71, and the wire
66 also forms a second
slot 72 extending from the second outer hole 46 to a second bridge 73 (Fig.
3E).
[0033] From the foregoing, it can be seen that, once the wire 66 has
begun to cut the first
and second slots 70, 72, the wire 66 is moved generally upwardly through one
of the slots, and
generally downwardly through the other of the slots. In addition, as the wire
66 is moved generally
upwardly and generally downwardly through the slots 70, 72, the wire is urged
against working
Date Recue/Date Received 2021-01-22
faces in each of the slots, because the wire is urged in the directions
indicated by arrows "C1",
"C2" in Figs. 3D and 3E. The wire 66 is urged in the directions indicated by
arrows "C", "C" as the
wire 66 is also moved generally upwardly and generally downwardly through the
slots until the
working faces of the slots reach first and second predetermined points 82, 84
(Figs. 3D, 3E). The
slots 70, 72 preferably end at the first and second predetermined points 82,
84 to define the first
and second bridges 71, 73.
[0034] It will also be understood that the width of the slots 70, 72 is
exaggerated
somewhat in Fig.3E for clarity of illustration. The width of each of the slots
70, 72 is approximately
equal to the diameter of the wire, e.g., the width of the slots may be
approximately 0.5 inch to
approximately one inch, or larger.
[0035] Each of the slots 70, 72 is defined by an inner wall 74 thereof
and an outer wall 76
thereof. It will be understood that the outer wall 76 forms part of the raise
wall 25, as will be
described.
[0036] As can be seen in Fig. 3E, as the wire 66 cuts through the rock
24, moving in the
directions indicated by the arrows "C1", "C2", the wire 66 partially severs an
internal portion 78 of
the rock 24 from a host portion 80 thereof. As will be described, the internal
portion 78 is to be
removed, in order to form the raise 22. Accordingly, the internal portion 78
is inside the raise
perimeter 26.
[0037] As can be seen in Fig. 3D, the first and second points 82, 84 on
the raise perimeter
26 are determined, at which the slots 70, 72 formed by the wire 66 end, to
form the first and
second bridges 71, 73. Once the wire 66 has reached the first and second
points 82, 84, the
rotation of the upper and lower sheaves 60, 64 about the central axis 30
ceases, and the wire
saws 58, 62 stop pulling the wire 66 through the slots 70, 72. At this point,
the wire cutting process
has been completed. The wire 66 is then removed from the outer holes 44, 46.
[0038] As can be seen in Figs. 3D and 3E, the first and second points 82,
84 preferably
are on opposite sides of the raise perimeter 26, i.e., it is preferred that
they are located 180 from
each other. Accordingly, the first and second bridges 71, 73 preferably are
also located 180 from
each other.
[0039] As can be seen in Fig. 3E, the internal portion 78 is connected
with the host portion
80 by the first and second bridges 71, 73. It will be understood that the
first and second bridges
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71, 73 are designed to support the internal portion 78 temporarily, and the
first and second bridges
71, 73 therefore must be sized accordingly. Those skilled in the art would
appreciate that the
sizes of first and second bridges 71, 73 preferably are determined according
to the specific
conditions in the rock 24 where the raise 22 is to be formed.
[0040] Those skilled in the art would also appreciate that, depending on
ground
conditions, it may be advantageous to drill more than two outer holes, and it
also may be
advantageous to have the wire cut slots between more than one pair of
oppositely-positioned
holes, so as to define more than two bridges between the internal portion and
the host portion.
Using multiple outer holes would involve incurring more costs, however, it
would permit each of
the bridges to be smaller.
[0041] Once the wire cutting process has been completed and the wire 66
is removed
from the outer holes 44, 46, the upper and lower wire saws 58, 62 are removed.
[0042] Preferably, the internal portion 78 of the rock 24 is then
blasted, using the blasthole
50, to form the raise 22. Those skilled in the art would appreciate that the
internal portion 78 may
be blasted in a series of relatively small blasts, starting at the lower end
56 of the blasthole 50.
For example, the blasting may be accomplished using crater blasting, at
suitable vertical intervals.
As an example, an initial region 86 of the internal portion 78 that is to be
blasted first is shown in
Fig. 4. The initial region 86 may be blasted with a crater blast. The
explosives are loaded from
the upper drift 34. It will be understood that the broken ground falls into
the lower drift 38 (as
indicated by arrows "Z" in Fig. 4), from which it may be removed.
[0043] Those skilled in the art would appreciate that, in this way, the
internal portion 78 is
removed from the host portion 80, e.g., in a series of crater blasts. The
broken ground from each
blast falls into the lower drift 38, and is removed before the next blast. In
this way, the internal
portion 78 is ultimately removed, forming the raise 22, as illustrated in Fig.
5.
[0044] The broken ground from each successive blast may be removed from
the lower
drift 38 by any suitable means. Those skilled in the art would be aware of
suitable means.
[0045] It will be appreciated by those skilled in the art that the
invention can take many
forms, and that such forms are within the scope of the invention as claimed.
The scope of the
claims should not be limited by the preferred embodiments set forth in the
examples, but should
be given the broadest interpretation consistent with the description as a
whole.
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