Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02948030 2016-11-10
- 1 -
B 2749
Method for mining a deposit
The invention relates to a method for mining a deposit, in particular a rock
or ore body,
in which raw material is stripped from the deposit with a stripping device.
The invention furthermore relates to an open pit mine for mining a deposit
which is
operated according to a method of such type.
The mining of deposits, for example the extraction of diamondiferous ores and
diamondiferous rock from extinct volcanic pipes, can be carried out in open
pit mining
and/or in underground mining. Generally, a deposit can be understood as the
existence
of exploitable minerals or rocks. The extraction of ores from ore deposits,
for example
the mining of diamond-bearing kimberlite deposits (primary deposits), is of
particular
interest for the raw material extraction and the processing industry.
Likewise, the mining
of deposits bearing gold and other natural resources is also of great
interest.
Fig. 1 shows a pipe-like vertically located deposit 1 that bears raw material
5. The raw
material 5 can be ore, e.g. kimberlite. The deposit 1 can crop out on a
deposit surface 3.
The deposit 1 having the raw material 5 to be mined is surrounded by waste
rock or
dead rock 6.
Deposits of such type can have been formed through geological activities or
fracture
zones, whereby the raw material has accumulated in vertical deposits due to
material
mounting up or has been shifted from a horizontal stratification into a
vertical position
through a fault.
CA 02948030 2016-11-10
- 2 -
Conventionally, a deposit 1 is mined in an open pit mine with a mining funnel
2, as
shown in Fig. 2, up to a mining depth Dl. The mining funnel 2 can be designed
such that
it is stepped in a spiral-shaped manner in order that the mining of raw
material 5 from
the deposit 1 and of dead rock 6 surrounding the latter can be handled
logistically by
means of transport vehicles, such as dump trucks. The mining funnel 2 can also
be
referred to as a mine or pit running downwards in a conical manner.
The mining of a deposit 1 in an open pit mine with a mining funnel 2 is, in an
economically viable manner, only possible up to a specific mining depth D1, at
the level
of which a deposit surface 3 can be located. Below the deposit surface 3
further raw
material 5 of the deposit 1 is located. The deposit 1 can either narrow
downwards, as
depicted in Figures 1 and 2, extend downwards at a substantially constant
width or
alternatively also widen in the downward direction. A deviating, irregular
course of the
deposit 1 can also occur. A mining method of such type is known from RU 2 261
331
C2.
A further mining of raw material 5 from a deposit 1, when having progressed in
open pit
mining as shown in Fig. 2, can only be carried out in underground mining below
the
maximum mining depth D1, since a further narrowing of the mining funnel 2
below the
mining depth proves to be impossible or uneconomical. However, underground
mining of
raw material 5 is often uneconomical due to high project development costs for
the
production of shafts and tunnels and their labor-exhaustive excavation.
Likewise, a possible enlargement or widening of the mining funnel 2 also turns
out to be
uneconomical since a high proportion of dead rock 6 to be mined in relation to
the
additionally extracted raw material 5 would render the additional raw material
extraction
relatively small. This corresponds to an unfavorable mining ratio (or strip
ratio or
stripping ratio).
The current mining of raw material in open pit mining or underground mining
therefore
has the drawback that raw material lying in deep strata or spatially limited
raw material
- 3 -
occurring in small quantities has to be left untouched since an economical
mining of
such isolated and in most cases particularly rich deposits is currently not
possible.
Furthermore, it is known that an open pit mine is flooded so that further
mining of the
raw material can then be carried out from the water surface by means of a
floating
stripping device. This can be taken from RU 2 312 989 C2 for example. However,
underwater mining methods as they are also known from DE 1 816 221 Al, DE 1
812
879 Al, DE 28 09 304 or DE 102 43 747 Al are relatively time-consuming and
cost-
intensive.
The invention is based on an o bje ct to provide a method for mining a
deposit, with
which raw material can be mined in an especially economical manner, in
particular
economical in mining up to greater depths.
The method according to the invention for mining a deposit, in particular a
rock or ore
body, has the following method steps: In a first mining step the deposit is
perforated with
a stripping device located on a deposit surface and in doing so raw material
is stripped
from the deposit. As a result, a perforation structure remains in the deposit
which
develops during the perforation between stripped areas of the deposit. In a
subsequent
second mining step the remaining perforation structure of the deposit is mined
at least
partially and in doing so further raw material is stripped from the deposit.
A deposit can be understood as a raw material deposit, in particular an ore
deposit.
More particularly, this can concern a diamondiferous ore deposit. The raw
material
stripped from the deposit in accordance with the invention can be rock or ore
in
particular. The deposit surface can be formed on a surface of an existing open
pit mine
or underground mine. Hence, as deposit surface this can concern any natural
surface or
one cropping out along the course of the deposit as a result of open pit or
underground
mining. The deposit surface can crop out along a horizontal section through a
deposit.
17147879)/1
CA 2948030 2018-09-04
CA 02948030 2016-11-10
- 4 -
The deposit surface can, from a bird's eye view of the deposit, be a closed,
round
surface. Such a round or cup-shaped deposit surface can in particular be found
in the
case of pipe-like deposits.
Within the meaning of the invention the perforation of a deposit is to be
understood as
providing holes in the deposit or puncturing it with holes. This can be
realized in a
checkered, mutually offset and/or mutually spaced manner. Preferably, the
perforation of
the deposit can be carried out vertically, whereby the deposit is perforated
vertically.
Accordingly, a vertical perforation structure can develop. Alternatively, the
perforation
can also be carried out in an inclined manner, i.e. not vertically or
perpendicularly. The
perforation structure which, in accordance with the invention, can remain
temporarily in
the deposit can be understood as a columnar structure that is formed during
the
perforation or puncturing of the deposit. In this, individual free-standing
columns or a
coherent three-dimensional meshwork or lattice can be present as a perforation
structure. The stripped areas of the deposit can be elongate cylindrical or
cuboid hollow
areas.
An essential basic idea of the method according to the invention for the
efficient mining
of a deposit resides in the fact that existing raw material is mined in two
steps, the
mining being effected in a mining direction, especially in a substantially
vertical mining
direction, such that the deposit is initially perforated, i.e. punctured
starting from the solid
surface in the mining direction. For the first mining step, simple and cost-
efficient mining
methods can be employed, with a sufficient amount of residual material
remaining to
ensure adequate ground stability. In a second step, the raw material remaining
between
the holes can basically be mined completely, wherein case a different mining
method
can be applied. Such a two-step mining method with a temporary perforation
structure
has in particular the advantage that by way of both time-shifted mining steps
raw
material can be mined efficiently from a deposit surface even up to great
depths.
In the first mining step approximately half of the minable raw material of the
deposit, i.e.
up to approximately 50 percent or more, can be mined from the deposit surface
through
perforation. The dimensions of the stripped areas in the deposit can be such
that as
CA 02948030 2016-11-10
- 5 -
early as in the first mining step a highest possible mining degree of the
minable raw
material of the deposit can be reached below the deposit surface. The
dimensions
comprise in particular diameters or widths of the stripped areas and their
depths. The
dimensions are defined by the stability of the deposit, in particular an ore
body, for the
application of a stripping device. A perforation spacing can be chosen such
that stripped
areas do not or hardly overlap. Before the second mining step the preferably
vertical
perforations are filled up, in particular with a liquid or a solid or
hardenable mass. This
allows an efficient second work step.
A preferred embodiment of the invention resides in the fact that the
perforated deposit is
flooded at least partially in the stripped areas and that in the subsequent
second mining
step the perforation structure of the flooded deposit is mined with a
stripping device
floating on the flooded deposit. The flooding of the deposit can be effected
with a liquid
such as water. A flooded surface, as for example a water surface, can thus be
located
above or below a deposit surface. If the flooded surface is located above the
deposit
surface, the perforation structure is situated completely below the flooded
surface. If the
flooded surface is located below the deposit surface, areas of the perforation
structure
lying overhead can jut out visibly. The flooding of the perforated deposit can
take place
during or after the first mining step. Alternatively or additionally, the
flooding of the
perforated deposit can also take place during the second mining step.
In the second mining step the perforation structure of the flooded deposit can
be mined
using the stripping device of the first mining step or another stripping
device, wherein
one of the stripping devices provided for the second mining step can float on
the flooded
deposit. The height or level of the flooded surface, which can also be
referred to as a
water table in the case of flooding with water, can be adjusted in height by
the degree of
flooding in order to create favorable working conditions for mining the
perforation
structure remaining in the deposit. As mining apparatus for the first and/or
second
mining step a drilling apparatus, a trench cutter and/or a grab or clamshell
can be used.
The floating stripping device can be a mining apparatus of the type arranged
on a
pontoon. Use can also be made of a floating dredge, a dredging vessel or a
dredger, on
which a drill, a cutter or cutting head and/or a grab arm can be arranged.
CA 02948030 2016-11-10
- 6 -
The flooding of the perforated deposit has in particular the advantages that
the
perforation structure in the deposit is supported by the flooding liquid and
that the
stripping device floating on the flooded deposit is protected against caving
into the
perforation structure of the deposit. Thus, a collapse of the perforation
structure under a
stripping device and a slipping thereof can be prevented, thereby enabling a
safe and
complete mining up to great depths below the flooded surface or the mining
surface
respectively.
Depending on the mineral content of the raw material, in particular ore,
stripped areas
that are flooded and filled with water can be left to settle for a specific
time until the
decomposition process has progressed so far that mining in a subsequent mining
step
can be effected such that the raw material can be stripped more easily. When
flooding
the deposit, the settling time can be envisaged as an intermediate step
between the first
and second mining step.
Between the first and second mining step, especially before flooding the
deposit and/or
after a specific number of stripped areas has been produced, an intermediate
step can
be provided, in which the existing perforation structure is initially mined by
a stripping
device, in particular by a hydraulic grab, that is located laterally of the
perforation
structure on the deposit surface or a terrain surface. A grab can partially
mine the
perforation structure that has been created by a drill in the first mining
step. The
intermediate step can be carried out depending on the stability of the
deposit.
According to a further preferred embodiment, for an efficient mining of the
deposit
provision can be made for the perforation of the deposit to be effected by
means of
drilling or cutting with a drill or cutter located on the deposit surface. The
drill can be a
drilling apparatus, more particularly a rotary drilling apparatus having an
auger and/or a
drilling bucket. For the mining of diamondiferous raw material it is
advantageous to use
drilling because when flushing liquid, in particular water, is used the raw
material, on
making contact therewith, decomposes after a relatively short period of time.
This has
the advantage that in a subsequent mining step the raw material can then be
loosened
CA 02948030 2016-11-10
- 7 -
more easily. The cutter can be a trench cutter. Alternatively or additionally,
a diaphragm
wall grab can also be provided for perforating the deposit. For mining, use
can also be
made of several identical or different stripping devices of such type. One or
several such
stripping devices can also be employed as the one or several stripping
device(s) floating
on the flooded deposit. It is also possible that several such stripping
devices are each
used simultaneously in the first and/or second mining step.
According to the invention provision can also be made for the first and second
mining
step to overlap, wherein the first mining step is started before the second
mining step.
Consequently, mining of the perforation structure in the second mining step
can be
started before the perforation of the deposit in the first mining step has
been fully
completed. To this end, it is necessary to employ in each case at least one
stripping
device for both overlapping mining steps.
According to a further embodiment variant of the invention it is advantageous
for the raw
material extraction if the stripped raw material is pre-crushed during the
perforation of
the deposit. Raw material, especially ore, can be pre-crushed by means of or
during a
drilling or cutting process. The drilling or cutting process can be carried
out with a drill or
a cutter. The pre-crushing of raw material has the advantage that treatment
costs for the
raw materials can be reduced. Alternatively or additionally, such an
advantageous
crushing process can also be realized with a pre-crusher. The pre-crushing or
crushing
of raw material can be understood as the break-up of the raw material.
In accordance with the invention another preferred embodiment resides in the
fact that
the stripped areas of the deposit are at least partially filled with a support
liquid. The
stripped areas, which can be large-scale bores, bores or cut trenches, can be
supported
with a liquid such as water or a suspension. If raw material is stripped in a
cutting
method using a cutter, the liquid or suspension, in addition to its function
as support
medium, can also serve as a transport medium for the stripped and loosened raw
material. After having been separated from the raw material, the liquid or
suspension
can be returned to the bore or cut trench as support liquid.
CA 02948030 2016-11-10
- 8 -
According to a further development of the invention a particularly favorable
mining
operation results from the fact that the perforated deposit is flooded with
the support
liquid. Preferably, this can be realized with a support liquid such as water.
The support
liquid can therefore be a flooding liquid. The flooding of the perforated
deposit with the
support liquid can be carried out up to a height below or above, for instance
5 meters
above, the deposit surface.
If the deposit is flooded during or in-between the first and/or second mining
step, in a
preferred embodiment of the invention the stripping device floating on the
flooded
deposit can be arranged on a floating carrier, in particular a pontoon or a
barge. On the
carrier a stripping device, a mining apparatus or a mining tool, such as a
hydraulic grab
or a cutter can be installed. Provision can also be made for a dredger as a
dredging
vessel that can have a stripping device with a grab and/or a cutting head. A
combination
of several such stripping devices located on one or several carriers is
possible, too. A
stripping device located on a floating carrier enables the stripping of raw
material up to
great depths.
When optionally using a floating dredge, a dredger or a dredging vessel and
mining raw
material underwater with a drill or a cutter, i.e. below the flooded surface,
raw material
stripped underwater can be pumped ashore by floating hoses and separated
there. The
second mining step, in which the perforation structure of the deposit is
mined, can then
also be referred to as an underwater mining step. For this, an underwater
stripping
device or an underwater stripping tool can be used. As floating carrier a
pontoon or
vessel can be employed.
For the stripping of the perforation structure, which can be partially or
completely
underwater after the deposit has been flooded, it can furthermore be of
advantage if the
location of the perforation structure is measured prior to the flooding in
order to carry out
a positionally accurate stripping underwater. In this way, the position of the
floating
stripping device and/or of the stripping tool located underwater can be
adjusted to the
perforation structure, the location of which is known as a result of
measuring. A mapping
of the perforation structure during or after the first mining step can thus
form the basis of
CA 02948030 2016-11-10
- 9 -
the second mining step. The mapping and/or determination of the position of
the
stripping device can be implemented by a satellite navigation system or
positioning
system for example.
According to a further embodiment of the invention it is expedient that the
stripping
device located on the deposit surface and the stripping device floating on the
flooded
deposit are identical, wherein the identical stripping device is a cutter in
particular.
Alternatively, the identical stripping device can also be a drilling apparatus
or a grab. It is
also possible to employ several stripping devices in the first mining step on
the deposit
surface and to use these stripping devices at least partially as floating
stripping devices
in the second mining step. One or several floating stripping devices can in
this case be
arranged on one or several floating carriers. On a single carrier, such as a
pontoon or
vessel, several stripping devices can also be arranged next to each other.
Basically, use can be made of any stripping device suitable for stripping raw
material in
a manner appropriate for a further processing of the raw material. According
to an
embodiment variant of the invention it is especially efficient if a stripping
device for the
second mining step is a grab, a trench cutter or a drilling apparatus. Such a
stripping
device can also be used in the first mining step.
Another advantageous embodiment of the invention can result from the fact that
the
stripped areas of the first mining step are refilled before the second mining
step is
carried out. Alternatively, the refilling of the stripped areas can also be
implemented
partially, i.e. in individual areas or up to a specific height. The filling of
the stripped areas
can be made with a mixture of a binding agent or dead rock. After the mixture
has
hardened the remaining perforation structure consisting of raw material
between the
filled areas can be mined in the second mining step. The filling of stripped
areas can be
carried out alternatively or additionally to a flooding of the perforated
deposit.
Stripping, conveyance, transport and treatment of stripped raw material is
basically
carried out in a known manner. According to an embodiment variant of the
invention, for
the mining of a deposit it is especially efficient if the stripped raw
material is dewate red,
CA 02948030 2016-11-10
- 1 0 -
separated and/or broken up. The dewatering, separation and/or break-up of raw
material
can be carried out by stripping devices or one or several separate devices for
one or
several of these possible further method steps. The dewatering and break-up in
a
crusher plant can take place on a pontoon. The broken-up raw material can then
be
conveyed ashore, i.e. to the edge of the flooded deposit, by means of floating
conveyor
belts.
For the loosening of raw material from the deposit an advantageous embodiment
of the
method according to the invention resides in the fact that during the first
mining step
blast holes are drilled into the vertical perforation structure and in the
first or second
mining step the perforation structure is blasted at least partially. To this
end, the blast
holes can be charged with explosive. Prior to this, the blast holes can also
serve for the
advance exploration of the deposit. The blasting of the perforation structure
can facilitate
its stripping in the second mining step. By preference, blasted raw material
can then be
stripped using a grab. A production of blast holes can take place before or
during the
perforation of the deposit in the first mining step. Blasting is particularly
advantageous in
the mining of hard ores or rock. Through blasting the raw material to be
stripped is
broken up, whereby the stripping of the broken-up raw material is rendered
easier in the
first and/or second mining step. The stripping of blasted, broken-up raw
material can
take place before or during the second mining step.
Basically, the perforation of the deposit can be carried out in any chosen
pattern and any
desired sequence during the production of individual perforation elements. A
perforation
element can be understood as a hole in the deposit, in particular a
(perforation) bore or
a (perforation) trench. A preferred embodiment of the invention resides in the
fact that
the perforation is effected with offset holes, in particular offset boreholes
and/or offset
trenches, in particular offset cut trenches. The offset holes are preferably
arranged in a
grid. As individual perforation elements the holes can form the entire
perforation
structure. The perforation structure can consist of individual bridges that
remain between
stripped areas in the deposit. The offset arrangement of holes in the deposit
has the
advantage that the perforation structure remaining in the deposit represents a
self-
contained, i.e. coherent, and stable formation.
CA 02948030 2016-11-10
- 11 -
The method for mining a deposit according to the invention can be used on a
deposit
surface cropping out naturally. The method with its first and second mining
step can also
be applied in a deposit that has already been mined partially in an open pit
mine,
wherein a mining depression, in particular a mining funnel is formed which can
be
flooded. The method can thus be used on the bottom level of a mining funnel.
Alternatively, the method can also be applied in a subterranean cavity, for
instance a
cavern or gallery, in which a deposit surface is present on the bottom level
of the
subterranean cavity.
The invention further relates to an open pit mine for mining a deposit which
is operated
according to the method pursuant to the invention for mining a deposit. The
method
according to the invention can be used as a supplement to another mining
method or as
an exclusive one.
The invention is explained further hereinafter by way of preferred embodiments
illustrated schematically in the accompanying drawings, wherein show:
Fig. 1 a perspective view of an exposed deposit;
Fig. 2 a section of an open pit mine with an exposed deposit;
Fig. 3 perforation of a deposit in a first mining step in a perspective
view of a deposit
surface with detailed views of the perforated deposit surface illustrated in
plan
view;
Fig. 4 a side view of a perforated deposit with a drill and with boreholes
filled with
support liquid;
Fig. 5 mining of a flooded deposit in a second mining step with a grab as a
stripping
device in a side view of the deposit;
CA 02948030 2016-11-10
- 12 -
Fig. 6 mining of a flooded deposit in a second mining step with a floating
grab as a
floating stripping device in a side view of the deposit;
Fig. 7 mining of a flooded deposit in a second mining step with a floating
cutter as a
floating stripping device in a side view of the deposit.
Fig. 1 shows an exposed rock or ore body of a deposit 1. The rock or ore body
contains
raw material 5. The deposit 1 or the raw material 5 is surrounded by waste
rock or dead
rock 6. The deposit 1 has a deposit surface 3 which crops out on a terrain
surface 4. The
deposit 1 can have a pipe-like or columnar structure. As shown in Fig. 1, this
can narrow
downwards or widen upwards.
Fig. 2 shows a section of an open pit mine with a mining funnel 2. The mining
funnel 2
reaches from the terrain surface 4 up to a mining depth Dl. At the level of
the mining
depth D1 a deposit surface 3 is located. The deposit surface 3 does not crop
out
naturally but as a result of the existing funnel-shaped mining funnel 2. The
mining funnel
2 can be designed such that it is stepped in a conical and spiral-shaped
manner from
the terrain surface 4 up as far as the deposit surface 3, wherein it narrows
from top to
bottom, i.e. from the terrain surface 4 towards the deposit surface 3. Above
the deposit
surface 3 the mining funnel 2 can be located and below the deposit surface 3
raw
material 5 of the deposit 1 is situated. The raw material 5 of the deposit 1
is surrounded
by dead rock 6 that can be located below the deposit surface 3 or the mining
depth Dl.
As shown in Fig. 2, in an open pit mine with a mining funnel 2 the deposit 1
has already
been mined up to the mining depth Dl.
Fig. 3 shows a deposit 1 in a side view with a perspective view of a deposit
surface 3.
The deposit surface 3 can be located in a mining depth D1 as a bottom level of
a mining
funnel 2 of an open pit mine or crop out naturally. If the deposit surface 3
crops out
naturally, the mining depth D1 can be located on or below the terrain surface
4 with a
small height difference. The boreholes 15 or stripped areas 9 can be sunk up
to a mining
depth 02 in the deposit 1. In this way, raw material 5 can be mined from the
deposit 1
CA 02948030 2016-11-10
- 13 -
between the mining depths D1 and D2. The perforation structure 7 then extends
between the mining depths D1 and D2.
On the terrain surface 4 a drill 20 or a drilling apparatus with a drilling
tool can be
arranged. With the drill 20 the deposit 1 can be perforated, in which case the
deposit 1
can be punctured with offset boreholes 15. The boreholes 15 that can be
arranged next
to each other constitute stripped areas 9 in the deposit 1 for mining raw
material 5.
The plan view A of the boreholes 15 in Fig. 3 shows a possible arrangement of
the
boreholes 15 in individual rows, wherein the boreholes 15 can be drilled
offset to each
other. The boreholes 15 within one row can be arranged at a constant distance
dl to
each other and different rows of the boreholes 15 can be spaced to each other
at a
distance d2. The boreholes 15 can have a diameter D. The diameter D can result
from
the used drilling tool of the drill 2, wherein the drilling tool can be an
auger or drilling
bucket. Between the individual boreholes 15 exploration or blast holes 13 can
be drilled
into the deposit 1. Between the boreholes 15 a perforation structure 7 is
located which
can constitute a coherent part of the deposit 1 punctured with the boreholes
15. To blast
the perforation structure 7 the blast holes 13 can be charged with an
explosive and
detonated individually, with a time lag or jointly. For exploration, a
measuring probe, e.g.
for seismic measurements or radar measurements, can also be introduced into a
blast
hole 13 before blasting.
In an alternative variant the deposit 1 can also be perforated by a cutter
(not illustrated in
Fig. 3). In the plan view B of a detail of the deposit surface 3 of Fig. 3
trenches 17 are
depicted that are cut in a cuboid manner when viewed from above. Just like the
boreholes 15 the trenches 17 can be arranged offset to each other in rows. In
a row the
trenches 17 can each be spaced from each other at a constant distance d3.
Between
the trenches 17 blast holes 13 can be arranged.
Fig. 4 shows a side view of an at least partially perforated deposit 1, from
which raw
material 5 has been stripped with a drill 20 that can be situated on a deposit
surface 3.
Stripped areas 9 thus formed as boreholes 15 can be filled with support liquid
11. For
CA 02948030 2016-11-10
- 14 -
the production of the boreholes 15 the drill 20 can be moved on the deposit
surface 3.
The boreholes 15 are sunk from the mining depth D1 up to the mining depth D2.
Between the boreholes 15 and the stripped area 9 the perforation structure 7
is formed.
As support liquid 11 e.g. water or a suspension can be used. The filling level
of the
support liquid 11 in a borehole 15 can reach up to the deposit surface 3 or up
to any
depth below the deposit surface 3 and above D2.
Fig. 5 illustrates mining of the deposit 1 in a second mining step after
perforation of the
deposit 1. The perforated deposit 1 shows several stripped areas 9 that can be
filled with
support liquid 11. The perforation structure 7 that remains in the deposit 1
and is formed
between the stripped areas 9 can be mined with a grab 24. The grab 24 can be
positioned laterally of the stripped areas 9 on the deposit surface 3. The
perforation
structure 7 can be mined sequentially with the grab 24. The filling of the
stripped areas 9
with the support liquid 11 can be understood as a flooding of the deposit 1.
The mining
of the perforation structure 7 can, in a first partial step, reach up an
intermediate mining
depth ID. Above the intermediate mining depth ID support liquid 11 can be
located that
can flood the deposit 1 at least partially or completely.
As shown in Fig. 6, the perforation structure 7, which has been mined in an
intermediate
step up as far as the intermediate mining depth ID by the grab 24 shown in
Fig. 5, can
be mined up to the mining depth D2. For this purpose, a grab 24, which can be
the grab
24 of Fig. 5, is arranged on a floating carrier 26. The floating carrier 26
floats on the
flooded deposit 1. The flooding of the deposit 1 can be carried out with
support liquid 11.
The grab 24 can mine underwater raw material 5 of the perforation structure 7
remaining
in the deposit 1, i.e. it can mine in the deposit 1 flooded with support
liquid 11 or water.
The grab 24 can also mine parts of the perforation structure 7 that have not
yet been
mined partially in a first mining step and still reach up as far as above the
flooded
surface 12.
Fig. 7 illustrates mining of the perforation structure 7 with a dredger 22 on
a carrier 26
that is able to float on the flooded deposit 1. The dredger 22 mines raw
material 5 of the
CA 02948030 2016-11-10
- 15 -
perforation structure 7 underwater. The dredger 22 can be employed
alternatively or
additionally to the grab 24 of Fig. 6 for mining raw material 5 of the deposit
1.
The method according to the invention for mining a deposit with a first and
second
mining step, in which a perforation structure is formed temporarily, allows
the mining of
raw material in a flexible and safe way up to great depths.
