Note: Descriptions are shown in the official language in which they were submitted.
115~2~
Background of the Invention
This invention relates to an apparatus for the
recovery of mineral nodules, especially manganese nodules
from the seafloor.
An ocean mining system is generally comprised of a
mining ship, a riser and a collector vehicle adapted to
travel on the seafloor. Nodules which exist on or partly
burried in the seafloor sediments are gathered by the
collector and are transported to the mining ship through
the riser. Since the mining operation is conducted at
depths of several thousand meters, the collector is one
of the most important components in the mining system.
Thus, the collector should have a high collecting effici-
ency and must be able to continuously and effectively
operate for a long period of time. Moreover, the collec-
tor should not feed muddy sediments to the riser since
otherwise the surface of the ocean would be considerably
polluted.
Summary of the Invention
It is, therefore, an object of an aspect of the
present invention to provide an apparatus which can
recover mineral nodules, especlally manganese nodules, from
the seafloor with a high collecting efficiency and which
can operate for a long period of time without encountering
troubles.
An object of an aspect of the present invention isto provide an apparatus of the above-mentioned type, which
can selectively recover nodules of desired sizes from the
seafloor. ~
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An aspect of the invention is as follows:
An apparatus for recovering mineral nodules from
the seafloor, comprising: an outer frame having a bottom
portion formed into a sledge so that said outer frame can
travel on the seafloor; an inner frame disposed within
said outer frame and having a bottom portion formed into
a sledge; a joint member connecting the front end of said
inner frame to a leading end portion of said outer frame
so that said inner frame may be trailed by said outer
frame on the seafloor; a buoyant member provided on said
inner frame to prevent said inner frame sinking into the
seafloor; a collecting chamber provided at the trailing
end of said outer frame; a transversely oriented cutting
blade secured to said inner frame and projected from the
bottom of said inner frame so that the seafloor surface
may be raised by said cutting blade when said outer
frame travels on the seafloor; a longitudinally extend-
ing duct provided on said inner frame having one end
open adjacent to said cutting blade and the other end
open adjacent to said collecting chamber; a plurality of
transversely arranged jet nozzles secured to said inner
frame and adapted to jet water therefrom; said collecting
chamber, cutting blade and jet nozzles being so arranged
that the summit of the seafloor raised by said cutting
blade may be scoured and introduced into said collecting
chamber through said duct by water jetted from said
nozzle; and a pump member mounted on said outer frame for
feeding water to said jet nozzles.
Brief Description of the Drawings
Other objects, features and advantages of the present
invention will become apparent from the detailed description of
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; preferred embodiments of the pre~ent invention which follows,
when considered in light of the accompanying drawings, in which:
Fig. 1 is a partial perspective view, cut away in part,
Ischematically showing one embodiment of the nodule collector
,laccording to the present invention;
Fig. 2 is an elevational view explanatory of the
collector of Fig. 1; and
Fig. 3 is a partial perspective view, cut away in part,
l¦schematically showing a collecting chamber of the nodule collector
¦¦of Fig. 1.
¦I Description of the Preferreu Embodiments
.
One embodiment of a nodule collector constructed in
accordance with the present invention is illustrated in Figs. 1
I'lthrough 3, and reference should be had first to Figs. 1 and 2.
!I The reference numeral 10 denotes an outer frame generally rect-
llangular in shape and having a pair of laterally spaced apart
¦Isledges 12 at its underside. Disposed within the outer frame 10
is an inner frame 14 which is also provided with a pair of sledges
,l16 at its suitable underside portions. As can be seen in Fig. 2,
1l the front end of the inner frame 14 is connected to the leading
end of the outer frame 10 by means of a jo~nt member, preferably
la flexible joint. As a result of this construction, the outer
llframe 10 can travel on the seafloor with the inner frame 14 being
iltrailed thereby. The inner frame 14 is provided with a buoyant
member 20 to control the uncerside level of the inner frame 14
relative to the surface of the seafloor. Good results are
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obtained wh~n the und~rside of the inn~r frame 14 is maintained
in the s~.e level as the seafloor.
A cutting blade 22 extends transversely between opposite
sides of the inner frame 14 and is fixed there. As shown in Fig.
2, the cut'ing blade 22 is protruded ~rom the bottom surface of
; the inner frame 14 and is oriented such that when the inner frame
1 14 moves forward, i. e. in the direction shown by the arrow X, the
cutting blade 22 c~n cut into the seafloor and rise it thereover.
I Preferably, the angle of inclination e of the cutting blade 22
1 is 60 or more.
In front of the cutting blade 22, a plurality of nozzles
24 are located. The nozzles 24 are supported to the inner frame
14 and their heads are generally laterally aligned along the
' transversely oriented cutting blade 22. The nozzles 24 are
adapted to jet water in directions so that the jet water may
impinge on the sumit of the seafloor surface risen by the cutting
blade 22.
~iounted on the outer frame 10 is a pump 26 for feeding
water to the nozzles 24. The nozzles 24 are connected to pipes 28
branched from a pipe 30 connected to the exhaust port of the pump
26. The inta~e port of the pump 26 is connected to a pipe 32
which opens at its free end to the leading end of the outer frame !
10. The pump 26 is operated by a driving means 34 mounted on the
outer frame 10.
The inner frame 14 has a duct 36 longitudinally disposed
therein. As can be seen in Fig. 2, one end of the duct 36 is
opened to recei~e water jet from the nozzles 24 while the other
- 5 -
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end ther~of` op~ns ~dJacently to a collection chamber 38 formed in
the trai].ing end of the outer frame 10.
In order to minimize tne loss in velocity of the jet
flows within the duct 36, the duct is oriented in the same
5 1l direction as that of water jet from the nozzles 24.
One embodiment of the collection chamber 38 is illust- !
f rated in Fig. 3. The collection cha~lber 38 has a front side 40
formed of a net member and serving as oversize rejection screen.
l The mesh size of the oversize rejection screen 40 is selected so
that the screen 40 may prevent passage therethrough of substances
whose sizes are larger that a desired upper size, e. g. larger
than 80 mm. The opposite side 42 and upper side 44 of the
collecting chamber 38 are also formed of a net member and serve as
Iseparation screen. The separation screen 42 and 44 has a mesh
lS '~size finer than the rejection screen 40 and allows passage there-
',through of substances having smaller sizes than a desired lower
~limit, e. g. smaller than 5 mm.
Disposed transversely at the bottom of the collecting
,chamber 38 is a screw conveyor 46 which is rotatingly driven by a
~motor 48. By rotation of the screw 46, the nodules collected at 'the bottom of the collecting chamber 38 are conveyed in the
direction indicated by the arrow Y. A riser pipe 50 extends
. i
downward into the collecting chamber 38 and terminates near the
~ bottom of the chamber 38. At the bottom of the chamber 38, a
,'nozzle 52 is mounted in vertical alingment with the riser pipe
50. The nozzle 52 is supplied with water from the pump 26
through a connecting pipe 54 branched from the pipe 30. The
other end of the riser pipe 50 is connected to a suction pump
(not shown) provided on the mining ship. Thus, the nodules
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conveyed by the screw 46 can be successively introduced into the
riser pipe 50 and transported up to the mining ship by the suction
force of the pump on the mining ship as well as pushing force of
, the jet water from the nozzle 52.
In operation, the nodule collector is placed on the
seafloor and is towed by the mining ship. Any suitable cable
may be used for towing the collector by the mining ship. The
¦riser 50 itself can be used for this purpose. When the nodule
llcollector travels across the seafloor at a predetermined speed,
~¦for example at one knot, the outer frame 10 is partly burried in
¦the seafloor by gravity. However, the inner frame 14 can travel
¦on the seafloor with its sledges being in contact with and in
parallel with the surface of the seafloor, since the inner frame
l 14 is provided with the buoyant member 20 and is connected to the
1 outer frame 10 by means of the flexible joint 18. As the collector ¦
is advanced, the cutting blade 22 fixed to the inner frame 14 can
cut into the seafloor and rises it thereover. By driving the
motor34 of the pump 26, clean sea water is introduced from the
¦intake of the pipe 32 and jetted from the nozzles 24 for the
~limpingement with the apex of the risen seafloor at a speed
sufficient to carry the nodules into the collecting chamber 38
through the duct 36. The arrangement and the number of the
nozzles 24 may be determined so that uniform ~et flows are
established throughout the duct 36.
, Nodules are known to exist partially burried in the
cl~yey seafloor sediment. Since~ with the nodule collector
according to the present invention, such nodules are tend to be
exposed on the surface of ~he seafloor by the rising action of the
;cutting blade 22, the amount of the sediments entralned with the
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nodules by the scouring ~ction of the Jet water from the nozzlcs
24 may be minimize~.
j The nodules and sediments removed from the seafloor
~Imove up the inclined duct 36 and substantially all the nodules
5 ll having diameters smaller than the mesh size of the oversize
I rejection screen 40 can enter into the collecting chamber 38.
Noaules having too large diameters to pass through the screen 40
are directed down onto the seafloor. The sediments introduced
into the collecting chamber 38 together with the nodules are
allowed to pass through the separation screen 42 provided opposite
to the oversize rejection screen 40 and are discharged out of the
collection chamber 38. Also nodules having smaller diameters than
the mesh size of the separation screen 42 may be discharged from
tne chamber 38, leaving nodules having selected range of diameters.
15 1I The nodules left within the collection chamber 38 are
successively displaced transversely by means of the screw conveyor
46 and are introduced into the riser pipe 50 by jet flows from the
¦nozzle 54 and suction force from the riser pipe 50 for trans-
l~portation to the mining ship. On the mining ship, the nodules are
1~1 separated from the se~water and recovered.
The nodule collector of this invention is very simple in ¦
structure and is capable of operating for a long period of time
without troubles, such as clogging of riser and entra~nment of
l¦muddy sediments in the recovered nodules. The combination of ~et
!~ nozzles and cutting blade may improve the collecting efficiency
¦of the collector and reduce the amount of muddy or silty sediments !
,introd~ced into the duct.
I, The invention may be embodied in other specific forms
I without departing from the spirit or essential characteristics
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" thereof. The present embodiments are therefore to be considered
in all respects as illustrative and not restrictive, the scope of j
¦ the invention being indicated by the appended claims rather than
l by the foregoing description, and all the changes which come
1 within the meaning and range of equivalency of the claims are
thereiore intended to be embranced therein
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